Simple Versatile Audio-Visual Alarm Circuit Diagram

This circuit uses an NE555 timer IC, some LEDs, a couple of piezo buzzers and a few other components to produce audio-visual effects as per your requirement. The timer NE555 and its equivalents are widely used for all sorts of audio and visual indications, such as door alarms. But the sound produced by these circuits may not be always pleasant to hear, or the light produced may not be visually appealing. With this circuit you can get different audio-visual effects.

Here we use LEDs for visual indication and buzzers for audible alarms as they require relatively low current to operate. By simply connecting some resistors and capacitors to NE555 we can obtain some interesting visual and audible effects as described here.

Circuit and working
Fig. 1 shows the circuit of the versatile audio-visual alarm which is built around timer NE555 (IC1), LEDs, buzzers and some resistors and capacitors. Resistors R1 and R2 and capacitor C1 determine the frequency of the LEDs’ blinking. The frequency is selected usually within the range of 0.1Hz to 20Hz, depending on your requirement. Values of resistors R1 and R2 can be above 1-kilo-ohm. Capacitor C1’s value can be between 1µF and 1000µF.

Simple Versatile Audio-Visual Alarm Circuit Diagram

Fig. 1: The versatile audio-visual alarm circuit

Fig. 2: Actual-size, single-side PCB for the circuit

  

 Fig. 3: Component layout for the PCB

Timer NE555 drives two outputs, namely, Group1 and Group2. Group1 is built around resistors R4 and R6 along with LED1 through LED6. Group2 is built around resistors R7 and R8 along with LED7 through LED12.

Each of the groups can be configured to get different outputs. For example, in Group1 you can use only the LEDs (LED1 through LED3) connected to +12V, or only the LEDs (LED4 through LED6) connected to the ground, or both branches of these LEDs, or only piezo buzzer PZ1, or PZ1 with any combination of the LEDs, or you can omit the entire Group1.

The components in Group2 can form the same combinations as the components in Group1. The difference between the Group1 and Group2 is the use of resistor R5 and capacitor C2. These two components give light-decay effect to the LEDs and a pleasant low-pitch sound to piezo buzzer in Group2. Value of resistor R5 can be between 75-ohm and 1-kilo-ohm and that of capacitor C2 between 47µF and 1000µF.

At point 1 (TP2) in the circuit you can see a rectangular wave signal. At point 2 you can see a triangular or trapezoidal-like signal. The signals at points 1 and 2 should go low, almost to zero, and should go high, almost to 12V supply voltage.

Power supply used is 12V, but it can be in the range of 4.5V to 15V as well, depending on the number of LEDs used in each branch. Higher number of LEDs will require higher voltage. LED13 glows when power supply is connected in the circuit.

Resistors R4, R6, R7 and R8 are selected according to the number and type of the LEDs used. If the values of these resistors are too low, the output of the timer will be overloaded and the LEDs in the upper and the lower branches will get activated simultaneously.

Overloading may also damage the NE555 timer. It is suggested to keep the total output current drawn from NE555 below 100mA.

On/off switch S1 is used to start or stop the alarm. Connector CON2 is an optional input point for connecting a variable element, such as a preset, for adjusting or varying the frequency of the square signal for more audio-visual effects.

Construction and testing
An actual-size, single-side PCB for the versatile audio-visual alarm is shown in Fig. 2 and its component layout in Fig. 3. After assembling the circuit on PCB, enclose it in a suitable plastic box.

Connect piezo buzzers PZ1 and PZ2 at their provided places in the PCB. Also connect 2-pin terminal CON1 for power supply. Connect CON2 for external input (optional). Before using the alarm circuit, check at the test points given in the table.

Sourced By: EFY Author :  Petre Tzv Petrov

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Audio Compressor circuit components Liabilities

We have seen here on the blog a very interesting audio compressor circuit, the audio compression is the process that adjusts the level of an audio signal, reducing the volume of loud sounds or amplifying low sounds by narrowing or dynamic range compression an audio signal.

The audio compression is used for sound recording, playback, radio and amplifiers for musical instruments, among other utilities. This circuit presented here is a single audio compressor that uses only passive components, or any semiconductor such as transistor, diode or integrated circuit.

Audio Compressor circuit

This compressor dynamic audio with passive components reduces the high signal to a lower signal, but more constant. If you look at this circuit will realize that has no power supply because it only reduces the input signal.

The basic operation is simple in its exit from the compressor will have a constant audio signal of approximately 70mV, so when the input voltage is between 100mV and 10Volts. The reduction control is made by the variable resistor P1 which may be a potentiometer or trimpot.

The diodes of this circuit should be germanium, because this type of diode has limits below the forward bias silicon diodes. Despite being simple this compressor circuit should work well, the drawback is its great attenuation, which makes it unfeasible for most audio applications.

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Simple Motor Bike Brake Horn Circuit Diagram

The circuit can be operated from 4.5V to 12V DC or direct from the brake point of the motor-bike, Resistor R7 should be replaced with 1-ohm. 1/2W in case of an 8-ohm speaker. T5 is a driver transistor. C3 polarity can be reversed for a sudden off of the circuit.

Simple Motor Bike Brake Horn Circuit Diagram

 

PARTS LIST
Resistors (all ¼-watt, ~+mn~ 5% Carbon)
R1, R7 = 2.2 KΩ
R2, R4 = 820 Ω
R3, R5 = 470 Ω
R6 = 4.7 KΩ
R8 = 10 KΩ
R9 = 4.7 Ω, 0.5W

Capacitors
C1 = 22 µF/25v
C2 = 4.7 µF/63V
C3 = 100v/16V
C4 = 0.047 µF
C5 = 0.01 µF

Semiconductors
T1 – T4 = BC148B
T5 = SL100
Miscellaneous
LS1 = 4Ω speaker

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Low-Cost 6-Bit DAC Circuit Diagram

For controlling the load of appliances such as cooling fans, low-wattage heaters, thermostats, low-wattage light sources, small electrical toys and test benches for loudspeakers, we need a power source whose voltage can be controlled in small steps and is capable of providing current of more than 1A. For that, we require low-resolution digital-to-analogue converters (DACs) with three to seven bits.

Here is the circuit capable of setting output voltage between 1.25V and 15V in 64 steps. The circuit can be adapted for a lot of applications.

 Low-Cost 6-Bit DAC Circuit Diagram

Circuit and working

The circuit of the low-cost 6-bit DAC is shown in Fig. 1. The DAC is built around IC 7406, hex inverter (IC3). We may also use IC 7407 with six followers without changing the PCB. Steps are generated with the help of 6-bit digital input code D0 (LSB) through D5 (MSB) at CON2. Consequently, 64 combinations are possible starting from 000000 to 111111. At each combination, you will have a pre-determined output voltage between 1.25V and the possible maximum 15V.

Inputs D0 through D5 are TTL and CMOS compatible. These can be generated by microcontrollers, parallel-interface adapters such as PPI8255A, PIA6820/1 and Z80-PIO. In the simplest case, inputs can be driven with switches connecting inputs D0 through D5 to ground 0V or to 5V.

The size of the steps is programmable with trimmer potentiometers VR1 through VR6. Consequently, we can produce regular or irregular steps according to the need, depending on the characteristics of the load being controlled.

You can set any output voltage with any potentiometer between 1.25V and the maximum. For example, if you have a transformer for 18V AC, you can set outputs between 1.25V and around 15V with any potentiometer.

For adjustment in the simplest case, apply a set of seven test codes, as listed below, on CON2; output on CON3 will be as under.

Test code with 7406 (invert with 7407):

000000 Vout=Vmax (unadjustable)

000001 Vout=1.25V (VR1)

000010 Vout=3V (VR2)

000100 Vout=5V (VR3)

001000 Vout=7.5V (VR4)

010000 Vout=9V (VR5)

100000 Vout=12V (VR6)

The maximum output voltage on CON3 and CON4 is with code 111111 on the outputs of IC3 and depends on the input voltage of IC2. Please note that, if you use 7407, the codes will be non-inverted, and if you use 7406, the codes will be inverted.

The 6-bit input digital code D0 through D5 is buffered with 7406 or similar (IC3). With an open collector, the IC works as a translator/buffer between standard TTL levels to higher voltages needed for LM317.

Fig. 2: An actual-size PCB layout of the low-cost 6-bit DAC

Fig. 3: Component layout of the PCB

If the requirement of current is more than 1A, then select adjustable regulator IC2 from series LM317T (1.5A), LM350 (3A) or any compatible adjustable-linear regulator.

This makes the DAC adaptable to a lot of applications. In many cases, there is no need to start the output voltage from 0V. This makes the solution even simpler.

Input digital code D0 through D5 is buffered with IC3, which should be obligatory with open connector. The preferred device is 7406 or better, with outputs that can work with up to 30V.

Power requirements are from a common configuration built around step-down transformer X1 (secondary voltage 18V to 20V with current 1A or above), bridge rectifier BR1 and voltage regulator IC 7805 (IC1). The mains power is applied on connector CON1. 5V is available at connector CON5.

The selection of mains transformer X1, bridge rectifier and heat sinks for IC1 and IC2 depends on the required maximum output current from the DAC. IC1 and IC2 can be mounted on a common heat-sink after proper mounting is done.

The load is connected to connector CON3. A DC voltmeter with 50V range is connected at CON4 for measuring the output voltage. The DAC can be tested with 12V/5W/0.4A light bulb, 12V/0.3A fan, heating element for thermostat with nominal current up to 0.3A and maximum current below 1A and similar loads.

Construction and testing

An actual-size, single-side PCB layout for the low-cost 6-bit DAC is shown in Fig. 2 and its component layout in Fig. 3.

Sourced By: EFY Author:  Petre TZV Petrov

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Flexible Electronic Circuits Based on silicon ink

In an effort to develop the next generation of microelectronic transistors, scientists have long been trying to find a new solution. To solve this problem, recent studies in the field of flexible electronics is completely focused on a variety of organic and metal-oxide ink to print, which often do not have all the positive electronic properties of silicon. But recently, a team of researchers from Delft University of Technology in the Netherlands has proposed a method that allows you to apply directly to the substrate is silicon, using liquid silicone ink and single laser pulses.

The ability to print on a substrate of silicon ink has been known for some time, but previously required step of thermal annealing at 350 ° C, which is too high a temperature for many flexible substrates. The new method proposed by researchers completely bypasses this step, converting the liquid silicon in the polysilicon used in the schemes.

The researchers applied the liquid polysilane directly to the paper in an oxygen-free environment. Then they were annealed layer via excimer laser [conventional tools used for displays of smartphones]. The laser burst lasts a few tens of nanoseconds, leaving the paper completely untouched. Test TFTs obtained in this manner was successful.

The greatest use of this technology can be found for wearable electronics, because it allows high-speed, low-power, flexible transistors with a surprisingly low cost. The technology also can be used for biomedical sensors and solar cells

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Compressor Circuit with 570/571 Compandor IC

Compressor Circuit with 570/571 Compandor IC circuit provide high gain for low amplitude input and provide low gain for high amplitude input. This action, in effect, produce a nearly constant amplitude even though the input has very high dynamic range (very high amplitude variation from time to time). The action of compression like this is needed in some situation, such as in maximizing modulation depth in broadcasting, or sustaining electric guitar signal which has very high variation between the plucking time and fading out.  The following circuit has complementary input/output characteristic and unity gain at 0.775 VRMS input. Voltage gain through compressor is square root of 0.7/Vin. Vin is average input voltage. This circuit  uses Signetics dual channel compandor IC.  570 has lower inherent distortion and higher supply voltage range (6-24 V) than 571 (6-18 V).

Compressor Circuit with 570/571 

Source :circuitsdiagram-lab

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50 watt 12 VDC to 220 VAC Power Inverter

This is the Simple 50 watt 12 VDC to 220 VAC Power Inverter. Power inverter (UPS Uninterruptible power supply) is a very useful device which can convert Low voltage from a DC source to high voltage AC. The most common power inverter is 12V to 240V inverter. Perhaps that is because 12V batteries are common. This type of power inverter usually draws current from a DC battery. This battery should be able to provide a high flow of electric current.

Normally lead acid batteries can server this purpose well. This current is then converted to 240V square wave alternative current so that we may empower those electric appliances which work on 240V instead of 12V. Inverter falls in the category of expensive devices so many people don’t buy them even they need them. What if I tell you how to build an inverter (UPS Uninterruptible power supply) yourself?

 Iverter circuit diagram 

Parts.

Transformer 12+12/220 (50W) ( you can make your own inverter transformer visit Make your own homemade (DIY) Electric Transformer)

2, metter copper wire (for winding)

2 Transistors 1047

2 Heat sinks to fit power transistors

Some wiring wire (for connections)

A wiro-board (To build circuit on)

A 12V battery of 12V power supply for testing purposes

1 Resisters 1 k

Method:

First of all you have to make some changes in transformer. If u are using 500 V transformer then take 18 to 22 gauge copper wire and on the one side of transformer’s core make five turn and put a point on it, and turn this point, and again turn the wire five times on the same direction. In this way u get three terminals. If u r connect the transformer to 220 V power supply then it gives 1.5 V on both terminals. Now put transformer D1047 on the palm of your hand and turn it such a way that number appears your way. Now you will see three points. The point on your left side is known as (B) Base, middle one is E and the right one is collector(C). (These are the information only for D1047)

connect the E of both sides of transistors with the outer terminal of secondary coil, after that connect the both outer terminals of the third coil with the base of the both heat sinks of transistor. then connect the collectors of both side by wires n then connect the 500 ohm resistor on emitter and resistor on either side. Now connect the middle terminal of primary coil by one to two ft long wire and clip (crocodile) it and attach this terminal always by the positive terminal, and with the negative terminal of battery connect the both collectors of transistor.

After that the central point of the third coil and a wire attach it with emitter to connect using a heavy ampere switch between both terminals of the Inverter primary coil to apply a capacitor which will prevent the current from the sparking. inverter will switch on as soon as starting to work.

Working:

With both the terminals of battery connect the positive and negative wires to its terminals positive to positive and negative to negative and then open the switch, slightly vibration starts in the inverter as switch is open. Now you can run it into 1 to 500 watt load.

This inverter also can charge the batteries, you just need to( on and off) the switch.

Charging:

You will need to switch off for battery charging and connect the primary coil indirectly with 220 V of power supply, after that battery will start charging. To converts it into UPS you needs only one relay. These relays are AC 220 V and 4.4 terminals.

For online help visitPak Science and technology Forum

Inverter circuit diagram for battery charging :

Inverter circuit diagram for Inverter operation :

 Sourced By: circuitsdiagram-lab.blogspot.com

Power Inverter Wattage Chart

inverters	Transformer voltages (Input)	Transformer Amps	Transformer watt	No of Transistors D1047
50 watt inverter	12 V	4 A	50 W	2
100 watt inverter	12 V	10 A	100 W	4 to 6
300 watt inverter	12 V	25 A	300 W	6 to 8
500 watt inverter	12 V	40 A	500 W	8 to 10
1000 watt inverter	24 V	45 A	1000 W	20 to 26
3000 watt inverter	24 V	125 A	3000 W	40 to 50
5000 watt inverter	48 V	105 A	5000 W	60 to 70
Note. table shows that requirement of D1047 transistors for different power inverter wattage

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Simple Low-Power Audio Amplifier

The small-signal amplifier is generally referred to as a voltage amplifier because it usually converts a small input voltage into a much larger output voltage. The audio power amplifier works on the basic principle of converting low-power audio signal to a suitable level to be delivered to the load.

This low-power amplifier circuit is useful for the amplification of sound from small-signal devices such as mobile phones, laptops or desktops.

Circuit and working
As shown in Fig. 1, this circuit is built around a step-down transformer (X1), bridge rectifier BR1, regulators 7809 (IC1) and 7909 (IC2), dual op-amp TL072 (IC3), low-power amplifier LM386 (IC4) and some other components.

The circuit can be divided into two sections—dual power supply section and amplifier section. The dual power supply section is built around step-down transformer X1 (230V ac primary to 12V-0-12V, 1A secondary) and two voltage regulators 7809 and 7909. IC 7809 is a positive voltage regulator, while 7909 is a negative voltage regulator. Diodes D1 and D2 are used to protect IC1 and IC2 against reverse voltages from capacitors connected to the regulators. These regulators provide ±9V regulated output for the operation of the circuit.

Use suitable heat sinks with the regulator ICs because they get hot during operation. In case of overheating, there is provision for a thermal shutdown.

The amplifier section is built around TL072 (IC3) and a low-power amplifier LM386. The op-amp A1 of IC3 operates as a low-noise preamplifier. Capacitor C8 is used in order to pass low frequency. The op-amp A2 of IC3 operates as a low-pass filter. For changing the cut-off frequency, you have to change the values of capacitors C11 and C12.

 Simple Low-Power Audio Amplifier circuit Diagram

LM386 is a low-power amplifier IC with built-in biasing and inputs that are referred to the ground. It has a gain of 20 and can drive a speaker of 8-ohm impedance.

The circuit is simple to use. You have to simply feed the output from a mobile phone, or any other low-volume device, into RCA1 socket on the PCB. The amplified sound can be listened-to through the speaker (LS1). Potentiometer VR1 is used for volume control.
 
Construction and testing
An actual-size, single-side PCB for the simple low-power amplifier is shown in Fig. 2. Its component layout is shown in Fig. 3. After assembling the circuit on the PCB, enclose it in a suitable plastic box.

Fix RCA1 socket on the front side of the box for an audio-in signal. Fix a three-pin connector on the PCB for connecting secondary terminals (12V-0-12V) of transformer X1 and to two-pin connector on the rear side for mains 230V AC, 50Hz. Fix the transformer firmly on the cabinet with screws or nuts and bolts. Connect the speaker affixed on top of the box or placed at a distance. Use a shielded cable for connecting to the RCA socket.


Before inserting IC3 and IC4 into their respective IC bases, verify that all the connections have been made properly.

Sourced By : EFY  Author :  S.C. Dwivedi

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Simple Sensitive LPG Leakage Alarm Circuit Diagram

Here is an ultra-sensitive LPG sensor that generates loud beeps when it senses any gas leakage. It detects vapours of liquefied petroleum gas anywhere between 200 and 10,000 ppm and drives a piezobuzzer to catch attention for immediate action. The buzzer beeps until the concentration of gas in the air decreases to a safe level. The circuit uses an MQ6 gas sensor, which is designed to sense LPG, propane and isobutane gases.

Circuit and working
Fig. 1 shows the circuit of the LPG sensor. The circuit is built around 5V voltage regulator 7805 (IC1), gas sensor MQ6 (GS1), counter IC 4060 (IC2) and a few discrete components.

GS1 is a six-pin gas sensor that can detect very small traces of LPG in the air and has a swift response time. However, it has very less sensitivity to alcohol and smoke. The sensor’s output is in the form of resistance.

Fig. 1: Circuit of the sensitive LPG sensor

As indicated in Fig. 1, the pins of GSI are H, A and B, two each on either side. H pins are for the heater with no polarity. Input pins A or B and output pins A or B can be connected either way round.

The coil heater inside the sensor can be easily heated with 5V DC. If pin A is connected to 5V DC through variable resistor VR1, use pin B as the output or vice versa. Both A and B pins can be shorted. In short, H pins are connected to positive and negative rails, A or B pin to 5V DC, and B or A for output.

The resistance value of GSI is different for various kinds and concentration of gases. So when using this sensor, sensitivity arrangement is very important. For accurate detection, it is necessary to calibrate the sensor for 1000 ppm of LPG concentration in the air with load resistance of about 20 kilo-ohms. (In the datasheet, the load resistance range of MQ6 is mentioned as 10 kilo-ohms to 47 kilo-ohms.)

Fig. 2: An actual-size, single-side PCB for sensitive LPG sensor

Fig. 3: Component layout for the PCB

Preset VR1 is used to adjust the sensitivity of the sensor to a particular gas concentration. Output from the sensor is connected to the base of transistor T1, which acts as a switch to trigger the alarm generator built around IC2.

IC2 is a binary counter IC that oscillates using capacitor C2 and resistor R5. Transistor T1 controls the reset pin (pin 12) of IC2. When the reset pin is high IC2 does not oscillate, and when this pin goes low IC2 starts oscillating.

Working of the circuit is simple. When the sensor detects LPG in the air, its output becomes high and transistor T1 conducts to make reset pin of IC2 low. This triggers IC2 to oscillate, which is indicated by LED1. After a few seconds, the buzzer starts beeping to indicate gas leakage.

The circuit works off 12V DC from a battery (BATT.1) or you can use an adaptor. IC1 provides regulated 5V DC supply for the sensor and IC2.

 Construction and testing
An actual-size, single-side PCB for sensitive LPG sensor is shown in Fig. 2 and its component layout in Fig. 3. After assembling the circuit on a PCB, enclose it in a suitable case with an opening to allow the gas to enter. Place the unit near the LPG cylinder or gas stove within a distance of one metre. Vary preset VR1 to adjust the sensitivity of the sensor.

To test the circuit, check 12V at test point TP1 with respect to TP0 to verify the correct power supply. Place the unit near the gas stove burner and turn on the burner for a few seconds without igniting. Then, turn ’the burner ‘off’ and adjust VR1 until you see LED1 glowing. TP3 should be low at this moment.

Sourced By: EFY : Author Name :  D. Mohan Kumar

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What’s New in Spectrum Analysers

There are general-purpose spectrum analysers, and then there are specialised ones. What kind of a spectrum analyser do you need? The answer to this question basically depends on the maximum frequency range that you want to measure, after including the harmonics and intermodulation products of the wanted signals. Although you can get a lab-grade oscilloscope that can analyse low audio frequencies up to microwave, this is overkill if you are going to use it with audio equipment. On the other hand, if you are working on very high frequencies, you might need an analyser that has a resolution good enough to differentiate between the smaller frequencies.

N9344C handheld spectrum analyser

Some new releases in this space are:
1. Tektronix MDO4000 mixed-domain oscilloscope, which is claimed to be the world’s first oscilloscope with built-in spectrum analyser.
2. R&S FSW-K91ac signal and spectrum analyser, which supports the new IEEE 802.11ac WLAN standard.
3. Anritsu MS2830A + OML MxxHWD, which has a  frequency coverage of up to 325 GHz.
4. Agilent N9344C HSA—an MIL PRF 28800 Class 2 compliant handheld spectrum analyser.
5. Scientech DSA800 Series spectrum analyser, which comes with a wide-screen display and is targeted at hobbyists.

The innovative lot includes:
1. Aronia X-Series USB RF spectrum analyser. Featuring specifications and performance similar to the equivalent Spectran handheld spectrum analysers, these RF spectrum analysers are controlled entirely via the USB interface using the real-time RF analysis software included with every unit.

2. Metageek WiSPY DBX—a pocket-sized tool designed for enterprise-level troubleshooting of WiFi environments. It has an amplitude range of –6.5 dBm to –100 dBm and amplitude resolution of 0.5 dBm. The device features an RP-SMA antenna too.

Purchasing an instrument for spectrum analysis being a major investment, make sure that you buy one that not only meets your today’s requirements but can also cope-up with the demands of tomorrow. With this in mind, selecting the ideal instrument should be a well-thought-out affair, with sufficient inputs from the people who are going to use it. Here are some pointers.

 1 Working with the IEEE 802.11ac WLAN standard?
If your project requires you to work with the upcoming 802.11ac WLAN standard, go for an analyser that is capable of analysing these signals. Although 802.11ac is still being defined, companies that chair the WiFi alliance have already brought out their own solutions using this standard.

The new standard requires 256 quadrature amplitude modulation (QAM), up to eight MIMO data streams, and a higher frequency band, along with wide bandwidths of up to 80 MHz. (The 160MHz bandwidth in this standard is achieved by using 80+80MHz mode.) Moreover, due to the 256 QAM, this standard requires an error vector magnitude (EVM) of -32 dB. The R&S FSW-K91ac tool features a very low EVM of less than -45 dB.


Announced on 20th June this year from Munich, the FSW-K91ac option enables the R&S signal and spectrum analyser to record and demodulate the full bandwidth of a WLAN signal in line with the new standard. It has a 31cm (12.1-inch) touchscreen with MultiView. MultiView provides users with simultaneous view of multiple measurements and applications. Pricing is available only on request.



 2 Spectrum analysers for education and hobbyists
Spectrum analysers for educational use and hobbyists should not only let them experiment with measurement testing but also act as a standard industrial instrument.

The DSA800 series from Scientech includes compact, light-weight and low-cost spectrum analysers that suit the education and hobbyist applications. The digital IF technology of this series helps in radio frequency (RF) applications like measurement of an RF amplifier’s characteristics, measurement of an RF bandpass filter’s characteristics, and measurement of voltage standing wave ratio.

The analysers offer a minimum resolution bandwidth of 100 kHz and are available with or without tracking generator. Their widescreen display, advanced measurement functions, electromagnetic interference (EMI) filter and quasi-peak detector kit, up to -135dBm displayed average noise level, phase noise of -80 dBc/Hz at 10kHz offset, total amplitude uncertainty of less than 1.5 dB, and the capability to interface through LAN, USB host, USB device and GPIB make them suitable for a majority of education and hobbyist applications.

The series comprises spectrum analysers to be used in basic electronics, basis communication, antenna and wireless communication labs.


 3 Millimetre-wave analysers
Millimetre-wave (mm-wave) analysers are intended for spectrum and signal analysis of emerging wideband communication systems. Using new capabilities, engineers can evaluate, characterise and manufacture products designed for emerging wideband standards, such as WiGig, including FCC Part 15 compliance emission testing requirements from 40 GHz to 200 GHz.

The MxxHWD harmonic mixer, based on a single-diode design, is available in waveguide bands from 26.5 GHz to 325 GHz. The harmonic mixer is a two-port frequency extension product with mm-wave interface for device-under-test (DUT) connection. The Anritsu MS2830A signal analyser, when coupled with the OML MxxHWD harmonic mixer, offers mm-wave frequency coverage from 26.5 GHz to 325 GHz.

 4 Radar, electronic warfare, EMI/EMC testing

Rapid advances in radar and electronic warfare technology have created the need for leading-edge testing technology and tools. Robust radar test equipment reduce uncertainty during the design process and deliver confidence in the integrity of increasingly complex designs.

Traditional signal analysers are unable to trigger on transient problems and the maximum available acquisition bandwidth in the mid-range is just 40 MHz.

To capture transients for analysis, Tektronix RSA5000 series offers frequency mask, frequency-edge, density, time-qualified and runt triggers. It can also be used to isolate hard-to-find hardware and software anomalies with cross domain triggering between multiple instruments. It can capture a seamless time record of RF frequencies into deep memory for up to 7 seconds at 85MHz bandwidth.


 5 Built for the field
For this kind of application, you require a spectrum analyser that is rugged, portable and performs well enough to get the job done. Compliance to MIL-PRF-28800 Class 2 is also important. This specification covers the general requirements for equipment used for testing and calibration of electrical and electronic equipment. The test equipment may be of commercial design and include general-purpose, special-purpose, peculiar, console-mounted, automatic test equipment and calibration standards.

The Agilent N9344C handheld spectrum analyser is built for the field. It features a channel scanner that can measure up to 20 channels simultaneously, as well as a spectrum monitor with spectogram display, record and playback. Moreover, it features AM/FM/ASK/FSK modulation analysis and time-gated spectrum analysis, which allows intermittent or burst signal spectrum measurement.

The Agilent N9344C is priced at ` 1,329,530 for the no-frills version, while a typical configuration would cost you ` 1,339,269.

Sourced By: EFY: Author name:  DILIN ANAND

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Seven-Colour LED Lighting Circuit Diagram

Presented here is a simple circuit that uses six red, green and blue (RGB) LEDs to generate a running-light effect in seven colours—blue, green, red, cyan, yellow, magenta and white. The RGB LEDs have four pins, one for each colour and a common cathode. Different colours can be produced by mixing the primary colours (i.e., red, green and blue).

Fig. 1: colours produced by three basic colours

Circuit and working
The circuit diagram for the seven-colour LED lighting is shown in Fig. 2. The circuit is built around timer NE555 (IC1), decade counter CD4017B (IC2), four-bit binary counter 7493 (IC3), driver IC ULN2003 (IC4), six RGB LEDs (RGB1 through RGB6), three BC547 transistors (T1 through T3) along with some basic components.

Fig. 2: Circuit of seven-colour LED lighting

The timer IC NE555 (IC1) is wired in astable multivibrator mode. It provides low-frequency clock pulses, the frequency of which is decided by timing components R1, VR1 and C2. The frequency of the timer can be varied using the preset VR1.

The output of IC1 at pin 3 is fed to decade counter CD4017B (IC2). IC2 has ten outputs, which go high in sequence when a source of pulses is connected to its CLK input (pin 14). Q0 through Q5 of IC2 are connected to IN1 through IN6 of IC4. Pin Q6 of IC2 is connected back to its reset pin 15 and input pin 1 of IC3 via diode D1. When Q6 pin of IC2 goes high, it resets IC2 and, at the same time, provides the high input clock to IC3 each time after the sixth clock of IC1.

IC3 is a four-bit binary counter, and its outputs QB through QD are connected to the bases of transistors T1 through T3 via resistors R21 through R23, respectively. The binary outputs of IC3 make corresponding transistors conduct and select a different colour after each cycle (see Table I).

The common-cathode pins of each RGB LED are connected to the outputs of IC4 as shown in Fig. 2. ULN2003 is used for driving these LEDs. You can add even more RGB LEDs in parallel to the existing ones to make a larger lighting system.

The working of the circuit is simple. When the circuit is switched on, the clock pulse is generated from pin 3 of the timer IC1, making outputs of IC2 high, sequentially, which decides the switching rate of LEDs that can be changed through VR1. The colours are selected by the binary output of IC3, which changes after every sixth pulse from IC1.

Fig. 3: A single-side PCB layout in actual size for seven-colour LED lighting circuit

Fig. 4: component layout for the PCB

Construction and testing
A single-side PCB for seven-colour LED lighting is shown in actual size in Fig. 3, and its component layout is shown in Fig. 4. After assembling the circuit on a PCB, enclose it in a suitable case. You can wire LEDs the way you like and connect on the PCB. The circuit uses a 5V DC supply.

To test if the circuit is functioning properly, check the input supply at TP1 with respect to TP0. The output pulses generated by IC1 can be checked at TP2 with the help of an oscilloscope. The frequency of these clock pulses can be varied by VR1. The clock pulse to the binary counter IC3 can be checked at TP3.

Sourced By: EFY: Author : Riju Thazhathuveettil.

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Simple Headphone Amplifier Circuit Diagram

This is the Simple Headphone Amplifier Circuit Diagram. You can use any NPN transistor. You can drive this circuit with a 9V batery. .

Simple Headphone Amplifier Circuit Diagram

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Diplomatic Optical Burglar Alarm Circuit Diagram

This is the simple Diplomatic Optical Burglar Alarm Circuit Diagram. This optical burglar alarm uses two 555 timer ICs (IC1 and IC2). Both the ICs are wired as astable multivibrators. The first astable multivibrator built around IC1 produces low frequencies, while the second astable multivibrator built around IC2 produces audio frequencies. General-purpose Darlington photo-transistor T1 is used as the light sensor. To increase the sensitivity of the circuit, NPN transistor T2 is used.

Place phototransistor T1 where light falls on it continuously. Phototransistor T1 receives light to provide base voltage to transistor T2. As a result, transistor T2 conduct to keep reset pin 4 of IC1 at low level. This disables the first multivibrator (IC1) and hence the second multivibrator (IC2) also remains reset so the alarm (LS1) does not sound.

Diplomatic Optical Burglar Alarm Circuit Diagram

When light falling on Darlington phototransistor T1 is obstructed, transistor T2 stops conducting and reset pin 4 of IC1 goes high. This enables the first multivibrator (IC1) and hence also the second multivibrator (IC2). As a result, a beep tone is heard from speaker LS1. The beep rate can be varied by using preset VR1, while the output frequency of IC2 can be varied by using another preset VR2. This circuit works off a simple 6V-12V DC power supply.


PARTS LIST
Resistors (all ¼-watt, ± 5% Carbon unless stated otherwise)
R1, R5 = 1 KΩ
R2 = 100 KΩ
R3 = 4.7 KΩ
R4 = 10 KΩ
VR1 = 1 MΩ
VR2 = 100 KΩ
Capacitors
C1 = 1 µF/16V
C2 = 0.01 µF
C3 = 0.047 µF
C4 = 0.01 µF
C5 = 47 µF/25V
Semiconductors
IC1, IC2 = NE555
T1 = 2N5777 Photo Transistor
T2 = BC547
LED1 = RED LED
Miscellaneous
LS1 = 8Ω / 0.5W

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RED PITAYA

 RED PITAYA – An All-in-One Oscilloscope, Function Generator, Spectrum & Frequency Analyser 

A low cost, portable Control & Instruments device that claims to replace expensive lab and field instruments.

We are in the era of mobiles, gadgets and instruments that are portable, packed with lot of features, have web connectivity and available at a very economical price point. Pick up any electronic gadget or instrument and it will fit in this definition, so why should test and measurement instruments take a back seat!

Introducing RED PITAYA - an innovative single board, low cost, high spec, multifunctional and portable PCB based electronic Test & Measurement Device that aims to replace expensive lab and field instruments.

RED PITAYA – Open Source T&M Device

Features
RED PITAYA is a programmable device powered by Xilinx Zynq7000 SoC that combines dual core ARM & FPGA and runs on Linux. It uses open source ecosystem approach which let users to download standard applications from 'Bazaar' and customize these applications at various programming levels and also develop new applications using source code and documentation available from 'Backyard'.

It is an ideal platform for electronic enthusiasts, students and universities, HAM Radio operators and research institutes.

Red Pitaya In Action

Hardware Specifications of Red Pitaya

Inputs:-
1. The main inputs are two independent channels that run at 125MS/s with 14-bit resolution
2. Four low speed inputs, each at 100kS/s and 12-bit resolution.
Outputs:-
1. Two main analogue outputs at 125MS/s and 14-bit.
2. Four low speed outputs, each at 100kS/s and 12-bit resolution.

Expansion is possible via USB (to add a flash drive, WLAN adapter or camera for instance), and also via a connector that provides 16x FPGA pins for GPIO (e.g. for a custom add-on module). The instrument is typically accessed over Ethernet via a web interface and can be easily connected to local networks. Users can connect to it by simply writing its IP in the address bar for their browsers.

It is also possible to log in, execute remote commands and transfer data via SSH. A handy USB UART interface provides access to the SoC serial console for configuration and debugging.

Hardware Specifications of RED Pitaya

Standard Applications/Functionalities

Oscilloscope - 2 channels @ 125 MS/s 14 bit digital with external or signal based triggering capability

Spectrum Analyser - 2 channels with 50 MHz bandwidth signal with waterfall diagram capability

Arbitrary Waveform Generator - 2 channels @ 125 MHz 14 bit arbitrary waveform generation with external triggering capability

Frequency Response Analyser - 2 channels with 60 MHz bandwidth

The web interface enables access to Red Pitaya’s functionality from the majority of browsers. Applications are available on iPhone, iPad, other smartphones, tablets and PCs.

Software Functionalities, Programming

Red Pitaya can be customised for specific applications above its standard specification. It is based on GNU/Linux operating system and can be customised at different programming levels. Available software interfaces include:

- HDL

- C/C++

- Scripting languages

- Matlab

- HTML based web interfaces

Red Pitaya Target Audience

ELECTRONICS ENTHUSIASTS. Red Pitaya is a great springboard for electronics enthusiasts, because it offers great user interface and can be easily reconfigured for any kind of interaction with outside world by simply modifying the available applications. Out-of-the-box applications, such as oscilloscope or spectrum analyzer, enable fast debugging of electronic projects

STUDENTS. The learning process is simplified by Red Pitaya Backyard containing all the application's source code. Students can start programming by applying incremental changes to the code and publish their work in Bazaar and easily get in touch with a wide range of technologies and knowledge. It is also very appropriate for PhD or other research projects

TEACHERS & PROFESSORS. Red Pitaya is a compact replacement for several expensive instruments and also a universal teaching tool. It enables learning of WEB and embedded application programming, FPGA, signal processing, machine vision applications and it can be controlled by Matlab as well.

HAM RADIO OPERATORS. Amateur radio community uses a wide set of instruments such as SWR meter, network analyzer etc. Red Pitaya has a potential to replace them all. Besides that it can also be used as a radio station or software defined radio (SDR)

RESEARCH INSTITUTIONS. Red Pitaya is very suitable solution for detecting and analyzing fast phenomena, as well as generating or simulating complex signals.

To Conclude

RED Pitaya with its out-of-the-box features, applications & high spec caters to the requirements of all electronics professional working in different areas & on different applications that too at a very affordable price. It is not hard to believe that in coming days RED PITAYA with so much of distinguished features can become inseparable/invaluable device for any electronics lab, design house, R&D center, and university.

Sourced By: EFY:

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Water-Level Indicator Schematic

Here’s a simple water-level indicator for overhead tanks that uses three LEDs (LED1, LED2, and LED3) to indicate minimum, middle, and maximum water levels in the tank.

The sensor probes comprise A, B, C, and D, where A is the common probe and B, C, and D are meant for sensing the minimum, middle, and maximum levels, respectively. When water in the tank touches sensor wires A and B both, a small current passes from A to B through water and to the base of transistor T1 via resistor R1. As a result, transistor T1 conducts, causing LED1 to glow. Similarly, when water touches sensor C, LED2 glows to indicate that the water has reached the middle level. Finally, when water touches sensor D, LED3 glows to indicate the maximum level of water. Thus all the three LEDs glow when the tank is full. At this stage, the motor should be switched off manually.

Water-Level Indicator Schematic

The circuit can be easily assembled on a general-purpose PCB and enclosed in a wooden box. The three LEDs should be mounted on the front panel of the box with a spacing of about 4 cm between them. Short lengths of four 18 SWG copper wires may be used for sensor probes. For the common sensor A, a bare copper wire of 18 SWG should be used. For sensors B, C, and D three single-core PVC wires should be used, with their insulation removed to a length of one centimetre towards the ends. All the four wires may be tied around a 12.5mm dia. PVC tube with nylon thread at different heights, without touching each other (not shown in figure).

The sensor probes should be kept in the tank vertically and connected to the main circuit using four flexible PVC wires of different colours.

The circuit is powered by a battery eliminator or a 6V battery and kept near the motor switchboard. The current drawn by the circuit, when all the LEDs glow, is up to 50 mA, which is less than the current drawn by a 6V bed-lamp.

The circuit costs around Rs 50.

Sourced y: EFY Author:  P. Venkata Ratnam

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Simple 6V to 12V Converter Circuit Diagram

 This inverter circuit can provide up to 800mA of 12V power from a 6V supply. For example, you could run 12V car accessories in a 6V (British?) car. The circuit is simple, about 75% efficient and quite useful. By changing just a few components, you can also modify it for different voltages.

Notes

• L1 is a custom inductor wound with about 80 turns of 0.5mm magnet wire around a toroidal core with a 40mm outside diameter.
• Different values of D3 can be used to get different output voltages from about 0.6V to around 30V. Note that at higher voltages the circuit might not perform as well and may not produce as much current. You may also need to use a larger C3 for higher voltages and/or higher currents.
• You can use a larger value for C3 to provide better filtering.
• The circuit will require about 2A from the 6V supply to provide the full 800mA at 12V.

6V to 12V Converter Circuit Diagram

Parts
R1, R4 2 2.2K 1/4W Resistor
R2, R3 2 4.7K 1/4W Resistor
R5 1 1K 1/4W Resistor
R6 1 1.5K 1/4W Resistor
R7 1 33K 1/4W Resistor
R8 1 10K 1/4W Resistor
C1,C2 2 0.1uF Ceramic Disc Capacitor
C3 1 470uF 25V Electrolytic Capcitor
D1 1 1N914 Diode
D2 1 1N4004 Diode
D3 1 12V 400mW Zener Diode
Q1, Q2, Q4 3 BC547 NPN Transistor
Q3 1 BD679 NPN Transistor
L1 1 See Notes
MISC 1 Heatsink For Q3, Binding Posts (For Input/Output), Wire, Board

Sourced By:  circuitsdiagram-lab

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Brushless DC Motor Driver Circuit Diagram

Use of brushless DC motors (BLDCs) is on the rise. But their control usually requires rotor-position information for selecting the appropriate commutation angle. Normally, a Hall Effect sensor is used to sense rotor position. But in cost-sensitive applications, a sensor-less commutation scheme is often desirable. The circuit described here uses a DRV10866 driver IC to drive a small BLDC fan, without using any position sensors. A BLDC fan’s speed can be varied smoothly, without the usual steps associated with a normal AC fan.

Circuit and working
Fig. 1 shows the circuit of a sensor-less BLDC motor driver. The circuit is built around an NE555 (IC1), a DRV10866 (IC2) and a few other components.

Fig. 1: Circuit of brushless DC motor driver

Fig. 2: An actual-size, single-side PCB for the brushless DC motor driver

  

 Fig. 3: Component layout for the PCB

DRV10866 driver IC from Texas Instruments is used to drive a small three-phase BLDC motor (M1). The circuit is of a three-phase, sensor-less motor driver with integrated power MOSFETs having drive-current capability up to 680mA peak. DRV10866 is specifically designed for low noise and low component-count fan-motor drive applications. A 150° sensor-less back emf scheme is used to control the three-phase motor.

A 100k pull-up resistor (R2) is used at pin 1 of IC2. Pins 2, 4, 7 and 6 of IC2 are connected to common, phase A, phase B and phase C of the BLDC motor, respectively. Pin 10 of IC2 is connected to pin 7 of IC1 to get the pulse-width modulated (PWM) signal from IC1 to control the speed of the BLDC motor.

The output signal (PWM) is available at IC1’s pin 7 (DIS) and not from the usual output pin 3 of the IC. The 25kHz (approx.) PWM signal’s duty cycle can be adjusted from 5% to 95% using potentiometer VR1. The speed of the BLDC motor can be controlled by varying the duty cycle of the PWM signal. Turning VR1 counter-clockwise lowers the duty cycle which, in turn, lowers the speed of the motor, and vice versa.

Construction and testing

An actual-size, single-side PCB for the brushless DC motor driver is shown in Fig. 2 and its component layout in Fig. 3. Assemble the circuit on the recommended PCB to minimise assembly errors. IC2 should be fitted on solder side of the PCB.

After assembling the components, connect a 5V DC supply to CON1 connector. To test the circuit for proper functioning, verify correct 5V supply for the circuit at TP1 with respect to TP0. Turn VR1 clockwise or counter-clockwise to increase or decrease the speed of the motor.

Author Name: Abhijeet Rai Sourced By: EFY

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Led Flasher Type of Police Circuit Diagram

This is the simple Led Flasher Type of Police Circuit Diagram. LED flasher same as that used in the police car, where the pace at which the lights flash is well paced and there is a sequence on each side. This type of flasher is also called strobe light or stroboscopic light. I began to develop a project to be published here, but by coincidence I ended up finding a circuit, easy to build and giving effect was wanting.

The electronic circuit flasher police is a Russian site, as the Russians have their own markup for semiconductor like this project, which uses KT815 transistors, for sure you will not find these transistors in a Western store, but of course are the replacements, in this case BD135.

Led Flasher Type of Police Circuit Diagram

Flasher LED Police type



This circuit is a classic of electronics, a flip-flop circuit, "astable multivibrators", this circuit is used for common flasher, but in this case two of this circuit were coupled to give the desired effect. The circuit flasher is so simple that can be done by a novice, as we see in the image below of the author, it was made on a standard printed circuit board.

How does the flasher Police

The flasher consists of two astable multivibrators, a leading astable formed by VT1 and VT2 transistors that generate the strobe and VT3 eVT4 transistors that have created short pulses to VT1 and VT2. The master oscillator is switched alternately strobe generator and the operating frequency of the generator is determined by the capacitors C1 and C4 and resistors R5, R6, R8 and R9.

You can use the trimpot R7 and R10 resistors to change the frequency of multivibrators, changing the frequency of blinking of the LEDs. The power transistors VT1 and VT3 and resistors R1 and R2 depend on the power of the LEDs used in the circuit.

Have the circuit power supply can be made with voltages 6-9 V, and its consumption is very low, enabling the use of batteries or battery. You can also change the operating voltage to 12 volts, just change some circuit resistors or put a 7809 regulator in input voltage.

Flasher LED type Police

I will give the most common equivalent found, the VT1 and VT2 transistors can be replaced by medium power transistors BD135, BD137 or BD139. The VT3 transistor can be replaced by transistors average power transistors BD136, BD138 or BD140.

But the transistor VT4 can be replaced by transistor 2sa611, BC556 or 2N4058 and other BCs of life. Below the video of the flasher police, the circuit can also be used for security systems, emergency flashing, holiday lighting, etc.


You can use higher power LEDs in this circuit since modify the resistors R1 and R2.

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