Simple Automatic Anchor Light Circuit Diagram

This is a Simple Automatic Anchor Light Circuit Diagram.Most of the cruisers do not use a masthead anchor light because the light is too high above the water level and actually makes it difficult to judge the position of the boat from just the anchor light, especially in a pitch-dark anchorage. That is why many people have devised their own forms of anchor lights that they stick lower to the deck on both sides of their boat.

Here is the circuit of a compact yet inexpensive automatic anchor light integrated with an ambient light sensor that turns it on and off automatically. This 12-volt LED light can be used as a traditional masthead anchor light and/or as an optional pretty clever custom-built anchor light. A typical commercial anchor light is shown in Fig. 2.

The circuit described here (refer Fig. 3) lets you control an electromagnetic relay so that it turns on a white LED light when the preset light level is reached and turns it off when a different preset level is reached. The circuit is built around NE555 IC (IC1). The 5mm light dependent resistor (LDR1) in the circuit triggers the 12V electromagnetic relay (RL1) as per the ambient light level. RL1 drives the 10mm white LED light source (LED2). Series resistor (R2) is included to limit the white LED current.

 Fig. 3: Circuit diagram of the anchor light

Note that switching threshold is determined by a 470k potentiometer (VR1) that causes the output to toggle with the preset threshold values. The light source (LED2) automatically switches on when it gets dark and switches off when there is sufficient ambient light. The 100µF capacitor (C1) provides a bit of hysteresis to prevent the circuit from jittering near the threshold level. The circuit is optimised for use with a nominal DC voltage of 12V drawn from any standard accumulator commonly used in boats.

Construction and testing

A single-side PCB pattern for the anchor light circuit is shown in Fig. 4 and its component layout in Fig. 5.

Fig. 4: PCB pattern of the anchor light circuit

Fig. 5: Component layout of the PCB

The circuit assembled on the small PCB can fit easily inside most prototype/custom enclosures, which should be waterproof for mounting on the masthead.

 Fig. 6: Suggested enclosure layout

 If possible, try to add some optics (lens and reflector) with the white LED (LED2) to spread the light outward. The 12V power supply input wires can then be connected to corresponding wires extending from the existing electric-points of the anchor light. Fig. 6 shows how the prototype may be assembled. Author’s prototype is shown in Fig. 7.

 Fig. 7: Author’s prototype

 Sourced By EFY : Authors name :T.K. Hareendran

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Two Channel RC Car Receiver

Someone anonymous left me a comment in this post asking that, since I had analyzed the transmitter, I also described the receiver. The comment I deleted, for the lack of care of its editor, but the request seemed right. A typical receiver of a cheap car made in China does not have much crumb. This I present is one that cost me between 3 and 4 euros (for those who are more familiar, about 4.5 USD).

Current Radio Control circuits

  There are three types of low-end radio controlled cars. Of course they do not have to be cars, the external form can be any. What matters is the circuit. Of course we talk about radio control at 27MHz, there are other controls that work with infrared but I will not talk about that.

  As I say, in RC models today we find only three types of circuits. Because the manufacturers are the same and barely change the schemes. The scheme depends on the channels that the car has. Channels are the independent actions you can perform.

  Diagram of a channel: These are the most basic and only have a button on the remote. They are the typical ones that nothing else turn them on the car goes forward. When we press the button it goes backwards and at the same time it rotates, to continue advancing as soon as we release the button. The circuit is very simple: a transmitter in the control and a receiver tuned in the car. As soon as the receiver picks up the command signal, it switches the address. Often the signal is not even modulated.

  Scheme of two channels: These have three states: forward, backward and stopped. They have two push buttons, one for forward and one for backward that can be independent or joined in a lever. The transmitter is an oscillator that can emit two tones of different frequencies (250Hz and 1000Hz), we already described the operation in this input. As for the receiver, the scheme is usually based on the integrated RX-3 from Silan. That is going to be the one we describe today.

  Scheme of five channels: They are the cars with functions of back-forward-turbo and left-right. In this case it is no longer comfortable to use different frequencies for each option, so digital modulation is used. Both the transmitter and the receiver use dedicated integrated. The TX-2B and the RX-2B respectively. We are not going to talk about them today

  Of course there are many more schemes. But these and their variants are the most common you will find in the bazaars. For the mid-range and modeling, especially in airplanes, other not so simple circuits are already used.

Two-channel receiver

This is the receiver of an RC car with two channels: forward / backward and stopped in the absence of signal. First let's look at the plate to get an idea:

We could reproduce the circuit from the tracks, as we did with the transmitter. But it is very boring, in addition in the datasheet of the RX-3 comes a scheme proposed by the integrated manufacturer. It is to be hoped that ours does not deviate too much and in fact it is very similar, deleting some components to save costs.

I have colored some sections so you can see them better (click to enlarge). Let's see how it works.

Section A: Radio frequency stage.

It seems that it is a regenerative receptor. The feedback is done through the 5.6kΩ resistance. These circuits apply positive feedback almost to the point of oscillating with the input signal. For how simple they are, they have very good sensitivity and selectivity characteristics. They have known each other since the earliest days of radio. The first patent is from 1914, with valves, of course.

The transmission reaches the antenna, passes through the tuned tank circuit and is amplified with the transistor. One of the diodes of the transistor also acts as an AM detector. Detecting and re-amplifying the tone with which the carrier is modulated. This type of design was used much earlier, when the cost of the transistors was very high. And that cost less than valves. The first transistor radios that came out proudly announced 6 transistors. Today the remote control that we analyze has 7, and the computer with which I write and read has several millions of miniature transistors inside.

The extracted audio tone goes to section B to be amplified

Section B: Audio amplification.

The integrated RX-3 incorporates two inverting amplifiers ready to use. The outer pins connect with what would be the equivalent of the inverter inputs.

The resistors and capacitors that make up this section are the feedback networks of both amplifiers. The first of them has an amplification of about 30dB which is greatly reduced for high frequencies by the effect of the 500pF capacitor in parallel with the resistance.

The second stage is configured with a gain of 10dB. All this grossly without counting the losses by the coupling capacitors, in series with the input resistors, which separate the direct current and only let the alternating current pass through.

The entire amplifier stage has a gain of 40dB. The detected tone is applied to pin 4 of the integrated. This is the demodulated signal input. When a 1000Hz tone arrives at this pin, pin 11 will be set high -forward- and the car will move forward. On the other hand when a tone of 250Hz arrives, the pin 9 -backward- will turn on and roll backwards

Section C: Bridge H.

When we apply tension to an engine it turns in a certain direction. If what we want is that we rotate one way or another at will we have to use a special arrangement of transistors to feed it. This circuit is called bridge H.

When the integrated applies voltage to the pin 11 -speed- the transistor Q9 goes to conduction. With it as a cascade reaction they also switch Q11 and Q13, grounding the left terminal of the motor and supplying positive voltage to the right one. And the engine will turn in one direction.

On the other hand, when pin 8 is activated -return- transistor Q8 is activated which in turn activates Q12 and Q10. Under these conditions, the left terminal of the motor would receive positive voltage while the right terminal is connected to ground. Just the reverse of the previous situation, and the engine will turn in the opposite direction.

There are variants of this scheme. In the scheme there are 5 NPN and 1 PNP transistors. However on the plate we have there are 4 NPN and 2 PNP. There are multiple possibilities but the idea is the same.

Section D: Food.

Finally, section D is the circuit power. There is not much to emphasize here. There are components that are missing in the commercial plate, for example the diode D1, which prevents against inversion of the batteries, they have saved it. As well as some filtering capacitors.

We see that the part that feeds the stage A is decoupled by a resistance of 100Ω and a capacitor. It serves so that no residual RF signal can leak into the power line and interfere with the integrated one.

In some circuits this part is not well designed, and the RF is coupled with the power supply, it can also pass through the parasitic capabilities between the tracks for example. In many cases of erratic behavior, especially with micro controllers this is the problem

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Automatic Bicycle Light

T his  automatic  bicycle  light  makes cycling in the dark much  easier (although you still need  to pedal of course). The circuit  takes  the  ambient  light  level  into account and only turns on  the light when it becomes dark.  The light is turned off when no  cycling has taken place for over  a minute or if it becomes light  again. The biggest advantage of  this circuit is that it has no manual controls. This way you can  never ‘forget’ to turn the light  on or off. This makes it ideal for  children and those of a forgetful  disposition.

Bicycle Light Image :

To detect when the bicycle is  used (in other words, when the  wheels turn), the circuit uses a  reed switch (S1), mounted on  the frame close to the wheel.  A small magnet is fixed to the  spokes (similar to that used with  most  bicycle  speedometers),  which  closes  the  reed  switch  once for every revolution of the  wheel. Whilst the wheel turns,  pulses are fed to the base of T1  via C1. This charges a small electrolytic capacitor (C2). When it is  dark enough and the LDR there-fore has a high resistance, T2  starts conducting and the lamp  is turned on. With every revolution of the wheel C2 is charged  up again. The charge in C2 ensures that T2  keeps conducting for about a minute after  the wheel stops turning. Almost any type of  light can be connected to the output of the  circuit.

Circuit diagram :

Automatic Bicycle Light Circuit Diagram

Part List :

Resistors
R1 = 1MΩ (SMD 0805)
R2,R4 = 100kΩ (SMD 0805)
R3,R6 = 1kΩ (SMD 0805)
R5 = LDR e.g. FW150 Conrad Electronics # 183547
Capacitors
C1 = 1µF 16V (SMD 0805)
C2 = 10µF 16V (SMD chip type)
C3 = 100nF (SMD 0805)
Semiconductors
T1 = BC807 (SMD SOT23)
T2 = STS6NF20V (SMD SO8)
Miscellaneous
S1 = reed switch (not on board) +
2-way right angle pinheader
BT1 = 3–12V (see text)

With a supply voltage of 3V the quiescent  current when the reed switch is open is just  0.14 μA. When the magnet happens to be in  a position such that S1 is closed,  the current is 3 μA. In either case  there is no problem using batteries to supply the circuit. The  supply voltage can be anywhere  from 3 to 12 V, depending on the  type of lamp that is connected. Since it is likely that the circuit  will be mounted inside a bicycle light it is important to keep  an eye on its dimensions. The  board has therefore been kept  very compact and use has been made of SMD components. Most  of them come in an 0805 pack-age.  C2 comes in a so called  chip version. The board is single sided with the top also acting as the solder side.

The print outline for the LDR (R5)  isn’t exactly the same as that of  the  outline  of  the  LDR  mentioned  in  the  component  list.  The outline is more a general one  because there is quite a variety  of different LDR packages on the  market. It is therefore possible  to use another type of LDR, if for  example the light threshold isn’t  quite right. The LDR may also be  mounted on the other side of the  board, but that depends on how  the board is mounted inside the  light. For the MOSFET there are also many alternatives available, such as the FDS6064N3 made  by   Fairchild ,  the  SI4864 DY  made by  Vishay Siliconix , the IR F74 0 4 made by IR F or the NTMS 4N01R 2G  made by ONSEMI. The reed switch also  comes in many different shapes and sizes; some of them are even waterproof and come with the wires already attached.

For the supply connection and  the connection to the lamp you  can either use PCB pins or solder the wires directly onto the  board. The soldered ends of the  pins can be shortened slightly so that they  don’t stick out from the bottom of the board.  This reduces the chance of shorts with any metal parts of the light. Do take care when you use a dynamo  to  power the circuit the alternating voltage must first be rectified! The same applies to  hub dynamos, which often also output an  alternating voltage.

Sourced By : circuitsproject.blogspot.com

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Oil Temperature Gauge for 125 cc Scooter

Lots of Far-Eastern scooters are fitted with GY6 engines. These already elderly units are sturdy and economical, but if you want to  “push” the power a bit (so called ‘Racing’  kits, better handling of the advance, etc.), you soon find yourself faced with the problem  of the engine temperature, and it becomes essential to f it a heat sink (of ten wrongly  referred to as a ‘radiator’) on the oil circuit. Even so, in these circumstances, it’s more than reassuring for the user to have a constant clear indication of the oil temperature. Here are the specifications we set for the temperature gauge we wanted to build: 

Oil Temperature Gauge Circuit Diagram :
.

• no moving parts (so not meter movement), as scooters vibrate a lot!;
• as cheap as possible (around £12);
• robust measuring transducer (avoid NTC thermistors and other ‘exotic’ sensors);
• temperature range 50–140 °C. (122 – 291 °F);
• audible and visual warning in case of dangerous temperature;
• compact;
• waterproof.

Let’s start by the sensor. This is a type-K thermocouple, as regularly used by multimeter manufacturers. Readily available and fairly cheap, these are robust and have excellent linearity over the measurement range we’re interested in here. The range extends from 2 mV to 5.7 mV for ten measurement points. The positive output from the thermocouple is applied to the non-inverting input of IC3.A,  wired as a non-inverting amplifier. Its gain  of 221 is determined by R1 and R2. IC3 is an LM358, chosen for its favourable characteristics when run from a single-rail supply. IC3.B is wired as a follower, just to avoid leaving it powered with its pins floating. 

IC3.B output is connected to pin 5 of IC1, an LM3914. This very common IC is an LED display driver. We can choose ‘point’ or ‘bar’ mode operation, according to how pin 9 is connected. Connected as here to the + rail, the display will be in ‘bar’ mode. Pin 8, connected to ground, sets the full scale to 1.25 V. R3 sets the average LED current. Pin 4, via the potential divider R7/R8+R9, sets the offset  to 0.35 V. Using R8 and R9 in series like this avoids the need for precision resistors.

As per the LM3914 application sheet , R4-R5-R6 and C5 will make the whole display flash as soon as D10 lights (130 °C = 226 °F). Simultaneously, via R10 and T1, the (active) sounder will warn the user of overheating. Capacitor C6 avoids undesirable variations in the reference voltage in ‘flashing’ mode. IC2 is a conventional 7808 regulator and C1– C4 filter the supply rails. Do not leave these out! D1 protects the circuit against reverse polarity. 

The author has designed two PCBs to be fit-ted as a ‘sandwich’ (CAD file downloadable  from [1]). In the download you’ll also find  a document with a few photos of the project. You’ll note the ultimate weapon in on-board electronics: hot-melt glue. Better than epoxy (undoable!) and quite effective against vibration. 

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Build a Faulty Car Indicator Alarm Circuit Diagram

Build a Faulty Car Indicator Alarm Circuit Diagram, Before taking a turn, either left or right, car drivers need to switch on the car’s turn-indicator lamps so that the approaching vehicle drivers can take precaution accordingly. An accident is likely to occur in case your car’s turn-indicator lamps fail to glow due to some reason or the other. Here’s a circuit that sounds an alarm if your turn-indicator lamps don’t glow, helping you to safeguard against any accident.

When both the the front and rear turn-indicator lamps (either right or left) glow, the current through the lamps (L1-L2 or L3-L4) causes a voltage drop across series resistor R1. This voltage drives pnp transistor T1 into saturation. In this condition, pnp transistor T2 does not conduct and hence relay RL1 does not energise. No sound from piezobuzzer PZ1 (connected to normally-opened (N/O) contacts of relay RL1) means that the turn-indicator lamps are working satisfactorily.

Faulty Car Indicator Alarm Circuit Diagram

When one or both of the turn-indicator bulbs are fused, the voltage drop across R1 is insufficient and pnp transistor T1 remains cut-off. In this condition, pnp transistor T2 conducts to energise relay RL1 and piezobuzzer PZ1 sounds to indicate that one or both the turn-indicator bulbs are fused.

Install the circuit (excluding turn-indicator lamps L1 through L4, which are already fitted in your car) near the driver’s seat so that the driver has easy access to blinker switch S1. To turn left, the driver needs to connect blinker switch S1 to left position to flash front and back left-turn-indicator lamps (L1 and L2). Similarly, to turn right, he needs to connect blinker switch S1 to right position to flash front and back right-turn indicator lamps (L3 and L4).

The value of resistor R1 is to be changed according to the bulb wattages.

Author:  Debaraj Keot

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Car Voltage Gauge

The Car Voltage Gauge is based on 3 parts. The input circuit is an Analog to Digital Converter (IC2 CA3162E). The purpose of this chip is to sample an analog voltage and convert it to a decimal value which is read by a Display/Decoder Driver (IC1 CA3161E). This chip will turn each seven segment display on through the driver transistor Q1 - Q3. The power is derived from the car and is converted to 5 volts by the 5 volt regulator. The circuit works as follows: The 10uf capacitor is charged up by the cars voltage. Its value is then read by IC2 and a decimal value of that voltage is provided to IC1 which multiplexes the three display units.

Each display is turned on sequentially with its appropriate value displayed. The transistors Q1 through Q3 control the drive to each seven segment display. By monitoring the cars voltage with an accurate multimeter you can adjust the "Zero Adj." pot and the "Gain Adj." pot for accurate readings. LED 1 and 2 are optional. They can be used to indicate power on or can light up a cut out display that says "Volts". This can be made by a plastic module that has a thin plastic cover on it with the word "Volts" cut into it. The LED's would be mounted inside the module. 

Source by : www.circuitsproject.com

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2-Pin Automobile Indicator Lamp Flasher Circuit with Buzzer

If you want to make a flasher unit for you motorbike then this circuit is just for you. This simple turn signal flasher circuit can be  easily built and installed in any two wheelers for the desired actions. The circuit employs just two 2-pins instead of 3 as found in other flasher circuits. Once installed, the circuit will faithfully flash the side indicator lights whenever the intended function is switched ON. The circuit also incorporates an optional buzzer circuit which can be also included for getting a beeping sound in response to the flashing of the lamps.

Parts List

R1, R2, R3 = 10K

R4= 33K

T1 = D1351,

T2 = BC547,

T3 = BC557,

C1, C2 = 33uF.25V

L1 = Buzzer Coil

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