Footstep Power Generation System using Microcontroller

Day by day, the population of the country increased and the requirement of the power is also increased. At the same time the wastage of energy also increased in many ways. So reforming this energy back to usable form is the major solution. As technology is developed and the use of gadgets, electronic devices also increased. Power generation using conservative methods becoming deficient. There is a necessity arises for a different power generation method. At the same time the energy is wasted due to human locomotion and many ways. To overcome this problem, the energy wastage can be converted to usable form using the piezoelectric sensor. This sensor converts the pressure on it to a voltage. So by using this energy saving method, that is the footstep power generation system we are generating power.

Microcontroller based Footstep Power Generation System

This project is used to generate voltage using footstep force. The proposed system works as a medium to generate power using force. This project is very useful in public places like bus stands, theaters, railway stations, shopping malls, etc. So, these systems are placed in public places where people walk and they have to travel on this system to get through the entrance or exists. Link

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Hovercraft Controlled By Android

A hovercraft is a non wheeled vehicle that can hover over land as well as water easily using high powered fans and aerodynamic design. We here propose an advanced hovercraft that uses high rpm motors interfaced with an avr family microntroller to achieve desired functionality. The motor below hovercraft rotates at a very high RPM that allows it to generate a force enough to make it hover on the surface thus reducing the friction below it to minimum. Then we use the motor propeller mounted behind it to push the hovercraft in forward direction. Now we also need to use a servo motor attached to the hovercraft rudder that helps the hovercraft to move in desired directions by bending the air at accurate angles. 

The system works collectively to hover while continuously managing servo as well as propeller motor to drive the hovercraft as desired. Now to control the hovercraft we here use an android application. The android application sends movement commands to the hovercraft circuit. The circuit consists of an Bluetooth receiver to receive and process these commands. The commands received by receiver are now processed by the microcontroller and it then operates all three motors accordingly as desired by the user. Link

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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.

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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Power 2h-30-Vatt 12 volts, working scheme

Not expensive, High-quality sound, Small parts and easy to assemble, Do not need to be tuned.Today can offer to your attention an amplifier that I have gathered from (almost) stuff I have lying in store. Long ago, working in the workshop, we often filmed amplifiers machines, since they come without tape recorders ​​and to put an ordinary tape recorder had to dismantle the amplifiers are !!! I left a couple of times since amplifier chips such as the LA4708. Time has passed since then a lot until my sister had not asked to do anything for his laptop to play in the yard with an acceptable quality and loud sound as speakers 2 pcs idle at home!

Power 2h-30-Vatt 12 volts, working scheme

It is taken from the datasheet half and half just from the people and schemes are proven over the years !!! If you look at the diagram, the capacitors C3 and C4 - a savings standing on the output of the amplifier, without a way (as if the sound disappears at high bass and not enough to drive the speakers). The amplifier where I desoldering the chip standing at the entrance storage choke (but I was too lazy to shake it, because it was a little too big standard, and the image at the top of his nebylo), it was decided to do without it !!! Increased denomination was in microfarads and capacitor C7 to 3300 microfarads, put dop.kondensatory input to the sound source and of the zener instead I put krenochku 5V to 5 foot (because it was under the hand) Well, all of the components that we need:

Sorry I forgot to add a couple of SMD capacitors there, standing at the entrance, but roughly the size of clear =) I must say that the capacitors C1, C2, C5, C6 (Mylar or polypropylene). Next Ludim, drills, soldered components from small to large. Unfortunately I lost zaglyuchila feshka and photos with my tinning and soldering = (There was only the result of the test and for 2 weeks =)

Put it on the active cooling, in Signet will be provided !!! My advice is not to actively, but rather to increase the area of the radiator. The following seals:

Power gives its net 20-30 watt channel! Tested on AS35! Keep in mind that this , no volume controls are not present !!! Before starting up the volume to a minimum !!! Starts amplifier from normal BP computer, it still works as well (there is no time to stick his body =)

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Simple Mini Offline UPS Circuit Diagram

Most of the systems are powered by AC mains. Uninterrupted power supply systems (UPSes) are there as a back-up to power the systems when mains supply is interrupted due to a power cut. A UPS differs from a standby generator in that it will provide near-instantaneous power by supplying the energy stored in batteries. In an online UPS, batteries are always connected to the inverter, which is always on, so that no transfer switches are necessary when power disruption occurs.

In an offline UPS, the inverter circuit is switched on when mains are not there. UPSes are available off-the-shelf, and one can select the system as per one’s requirement, back-up time being one requirement. However, one can construct a UPS of one’s own choice. Here is a circuit of an offline UPS, which a hobbyist can make at a reasonable cost. The capacity of the UPS is 350VA, so it can be used for any equipment with a load below 350VA. The UPS can be upgraded to 1kVA by making just a few changes.

Circuit and working
The circuit diagram of the mini offline UPS shown in Fig. 1 has the following four sections:
Section 1: Mains/inverter change-over section
Section 2: Inverter section
Section 3: Battery-status-indicator section
Section 4: Oscillator section

Above-mentioned sections and their interconnections are appropriately marked in the circuit diagram.

Mains/inverter changeover section. The circuit of this section is built around step-down transformer X1 (230V AC primary to 12V-0-12V, 500mA secondary), a 12V DC, 3C/O (changeover) relay (RL1) and a few other components. 230V AC mains is connected to the circuit through connector CON7. Output of the UPS is available at connector CON8, which is actually a 3-pin socket.

Mains voltage is rectified by diodes D1-D2 (1N4007). The full-wave rectified output is smoothened by capacitor C1. DC voltage so generated is applied at pins 10 and 11 of relay RL1. When mains voltage is there, the relay gets energised to affect the changeover to connect the mains to the output of the UPS.


The circuit is not on a PCB and has been wired externally. Relay contacts in the circuit diagram are shown in a de-energised state of the relay.

Inverter section. This section comprises transformer X2, npn power transistors 2N3055 (T1 through T8) and power diodes 1N5407 (D3-D4). Transistors, which are eight in number, are connected in two banks. The number of transistors per bank will depend on the required VA rating. The prototype has been made for 350VA rating by using four transistors per bank. The number of transistors required per bank for different capacities are:

• 550VA – Five
• 650VA – Six
• 1000VA – Seven

Fig. 1: Circuit diagram of the mini UPS

This circuit is also not on a PCB and has been wired externally. Transistors T1 through T8 have been fitted on the same heat-sink. Mounting of transistors has to be done in such a manner that their base and emitter are not in contact with the heat-sink. The metal body of the transistor is the collector. Collectors should be separated from the heat-sink. This is done by using mica separators between the heat-sink and metal body of the transistor. In short, all three terminals should be separated from the heat-sink. The arrangement is shown in Fig. 2.

Interconnections of transistor terminals, transformer X2, diodes D3-D4, battery-status-indicator section and oscillator section are shown in a combined circuit diagram (Fig. 1). The heat-sink should also be isolated from the UPS box.

Fig. 2: Mounting of transistor 2N3055 on heat-sink

  

 Fig. 3: Details of the 3C/O relay

Fig. 4: PCB of the oscillator and the battery-status section

Fig. 5: Components of the PCB

Battery-status-indicator section. This section monitors the state of the battery. It is connected to the battery by CON3-CON4 combination. Connect these as per polarity of the 12V battery. Overcharge status of 14.4V is set with the help of preset VR3. Overcharge status is indicated by LED2.

We have to switch off S1 to protect the battery from overcharging. During normal charging, no LED (LED1 or LED2) will glow. If S1 is off, the rectifier circuit formed by diodes D3 and D4 will be disabled, which, in turn, will stop further charging of the battery. Lower limit of the battery is set at 11.3V with the help of preset low level of the battery, which will be indicated by LED1. Switch S1 has to be closed to restart the charging of the battery. Load should be disconnected when battery voltage is lower than 11.3V and mains voltage is not there.

Oscillator section. This circuit comes into action when mains voltage is not there. It, along with two banks of transistors T1-T8, will generate low-level AC voltage (15V-0-15V) at terminals of transformer X2, which will be stepped up by transformer X2.

The circuit is built around NE555 timer (IC2), dual JK flip-flop 4027 (IC1), transistors SK100 (T11-T12) and BC547 (T9-T10), voltage regulator 7805 (IC3) and a few other components. NE555 timer is configured in astable multivibrator mode.

Frequency of the timer is set to around 200Hz with the help of preset VR1 in order to get around 50Hz line frequency at CON1. Output of the timer from its pin 3 is fed to pin 3 (CP2) of second flip-flop of IC1 as clock pulse. Output of this flip-flop from pin 1 (Q2) is used to clock the first flip-flop. Outputs Q1 and Q1 are applied to the bases of transistors T9 and T10, respectively. Transistors T11 and T12 amplify these outputs to about 2.2V, which are applied to base terminals of transistors T4 and T8 for further amplification to 12V. Con1 and Con2 are used to connect outputs from the oscillator section to the two transistor banks.

The circuit is powered by a regulated 5V DC provided by voltage regulator 7805. Input to the regulator is the battery voltage, which we get by connecting Con5 to Con6. Battery voltage reaches pin 1 of regulator through pin 9 and pin 3 of relay RL1 and switch S2 is closed. When mains voltage is present, pin 9 and pin 3 are disconnected due to activation of the relay. Power supply to the oscillator section is interrupted, resulting in deactivation of the inverter circuit.

Relay RL1
Relay RL1 affects the necessary changeover required in the system due to the presence or non-presence of mains voltage. It is a 12V, three contacts changeover (three-poles  double-throw) relay. The arrangement of poles and contacts is shown in Fig. 3.

The coil of the relay is between terminals 10 and 11. Terminals 7 and 8 are shorted. Connections of remaining terminals of the relay are shown in circuit diagram (Fig. 1).

Working of the circuit
The UPS works in two modes:
1. When AC power is present
2. When AC power is absent

When AC power is present. When AC mains power is present, transformer X1 gets 230V AC input mains supply. Relay RL1 is therefore energised. Terminals 7, 8 and 9 of the relay come into contact with terminals 4, 5 and 6, respectively. Phase of the incoming AC mains supply gets connected to terminals 4, 7, 5 and 8 of the relay and the output socket where we connect the load. In this manner, mains are transferred to output socket CON8 of the UPS.

Fig. 6: The final assemblage enclosed in a cabinet (front panel)

  

 Fig. 7: The final assemblage enclosed in a cabinet (internal wiring)

When switch S1 is closed, the phase of the input mains gets connected to 230V tapping of transformer X2 through terminal 5 as it is in contact with the terminal 8 of the relay. As the neutral connection is common, transformer X2 acts as a step-down transformer. 230V AC is stepped down to 15V-0-15V AC and rectified to DC voltage by a full-wave rectifier (diodes D3-D4). Capacitor C7 is connected across the center tap of transformer X2. It is not included in the PCB. It is recommended to use a current limitter (say 4.7-ohm, 20W resistor) in series with positive terminal of the battery using suitable arrangement. The value of this current limitter will depend on your requirement, so it is not shown in the circuit here.

DC voltage so generated is used to charge the battery. At the same time, terminal 9 of the relay comes into contact with terminal 6, which disconnects power supply to the oscillator circuit and deactivates the inverter circuit. Switch S1 should be open when the battery is fully charged, which will be indicated by lighting up of LED2.

When AC mains power is absent(power cut). When AC mains power is off, transformer X1 does not get 230V AC supply. Relay RL1 therefore does not energise. Terminals 7, 8 and 9 of the relay come into contact with terminals 1, 2 and 3, respectively. Terminal 9 is connected to the positive terminal of the 12V battery, which is extended to the oscillator circuit. Inverter circuit comes into action.

Transformer X2 is now a step-up transformer. AC voltage from 240V tap of transformer X2 is connected to terminal 1 of the relay. As terminals 7 and 8 are in contact with terminals 1 and 2 of the relay, 240V AC gets connected to output socket CON8. Neon lamp N1 is connected between terminal 2 and neutral. It glows when the UPS is on. The output is connected to 240V tapping because there will be a voltage drop when load is connected to the UPS.

Construction and testing
Combined actual-size, single-side PCB for the oscillator section and the battery-status section is shown in Fig. 4 and the component layout in Fig. 5.

If needed, the PCB can be cut into two portions along the dotted line and mounted separately. Rest of the circuit has been wired using connectors. The final assemblage of the mini offline UPS is enclosed in a cabinet as shown in Fig. 6. The internal wiring is shown in Fig. 7 and the rear panel is shown in Fig. 8. All switches, indicators and terminals for connecting the battery and output socket are to be placed aesthetically on the front panel of the cabinet.

Fig. 8: The final assemblage enclosed in a cabinet (rear panel)

Fuse F1 (1A) is used to protect the device from any short circuits. All connections should be made very carefully. The load should not exceed 350VA. For troubleshooting, check voltages at various test points as listed in the table.

Caution. Please be careful as the circuit operates on 230V AC.

Sourced By: EFy Author:  ZameerudDin Syed

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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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