This is a basic circuit of car horn and lamp flasher that starts playing the vehicle horn at whatever point your vehicle is backward rigging. The circuit (First Diagram) utilizes double clock NE556 to create the sound. One of the clocks is wired as an astable multivibrator to produce the tone and the other is wired as a monostable multivibrator.

How the reversing gear horn and lamp flasher circuit work

Working of the circuit is basic. At the point when the vehicle is backward rigging, turn around gear switch S1 of the vehicle gets shorted and the monostable clock triggers to give a high yield. Thus, the intersection of diodes D1 and D2 goes high for a couple of moments relying upon the timeframe created through resistor R4 and capacitor C4. Now, the astable multivibrator is empowered to begin swaying. The yield of the astable multivibrator is taken care of to the speaker through capacitor C6. The speaker, thus, produces sound until the yield of the monostable is high.

At the point when the intersection of diodes D1 and D2 is low, the astable multivibrator is debilitated to quit wavering. The yield of the astable multivibrator is taken care of to the speaker through capacitor C6. The speaker, thusly, doesn’t deliver sound.

Collect the circuit on a universally useful PCB and encase in an appropriate bureau. Interface the circuit to the vehicle invert switch through two wires with the end goal that S1 shorts when the vehicle gear is turned around and is open in any case. To control the circuit, utilize the vehicle battery.

The flasher circuit (Second Circuit) is worked around clock NE555, which is wired as an astable multivibrator that yields square wave at its pin 3. A 10W auto bulb is utilized for flasher. The glimmering pace of the bulb is chosen by preset VR1.

Gather the circuit on a universally useful PCB and encase in a reasonable bureau. The flasher bulb can be mounted at the vehicle’s back side in a reflector or a tight painted appropriate fenced in area.

Horn and Lamp Flasher Circuit Note

A higher-wattage bulb may diminish the force of the front lamp. You can encase both the carreversing horn and flasher circuits together or independently in a bureau in your vehicle.

Download this car horn and lamp flasher circuit in PDF document:

Horn and Lamp Flasher Circuit for Car Reverse Mode

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This is the glow plug control module unit to raise the air temperature inside the engine cylinder for quick and reliable starting, to extend the battery life and reduce the diesel consumption. In diesel engines, the air in the cylinders is not hot enough to ignite the fuel under cold conditions. Therefore every cylinder of these engines is fitted with an electric heater known as “glow plug”. A control module circuit is important to optimise the functioning of glow plugs.

How the Glow Plug Control Module Works

It utilizes a simple timer circuit built around MOSFET T1 for reliability and simplicity. Momentary pushing of switch S2 charges capacitor C1 rapidly via resistor R1. When the voltage on capacitor C1 exceeds the threshold voltage of the gate (G) of MOSFET T1, it starts charging reservoir capacitor C2 and simultaneously energises relay RL1. MOSFET T1 remains conducting as long as the voltage on C1 is greater than the threshold voltage of the MOSFET gate.

The “on” time period depends on the value of capacitor C1 and resistor R2, which govern the discharge current of capacitor C2. The component values given here will produce “on” time of around 25 seconds. In effect, when you press switch S2 momentarily, the relay energises for about 25 seconds and the glow plug gets the power supply through its contact.

The red LED (LED1) indicates that the heating process of glow plugs is “on”. When the “on” time is over, the green LED (LED2) turns on for a while, followed by a short beep from the buzzer, which indicates that the engine is ready for starting. Glow plugs draw a heavy current, hence high-current-rating contacts of an automotive relay are needed.

Build the glow plug control module unit on any general purpose PCB and mount it in a suitable case/box. Connect the glow plug wire to the relay contact. The 12V battery source that already available with the vehicle can be used to power the circuit. Connect the piezobuzzer and LED1 and LED2 through an external connection and place it at a convenient location for the driver to work.

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All distances mentioned before can vary, depending on infra-red transmitting and receiving LEDs used and are mostly affected by the color of the reflecting surface. Black surfaces lower greatly the device sensitivity.

Simple Explanation:

• The Q1 photo detector picks-up the infrared beam generated by IR LED1 and IR LED2 and reflected by the surface placed in front of it.
• IR LED1, IR LED2 and Q1 are placed facing the car on the same line, a couple of centimeters apart, on a short breadboard strip fastened to the wall. Q1 picks-up the infra-red beam which generated by IR LED1 and IR LED2, and reflected by the surface placed in front of it.
• If there is a obstacle the IR beam will radiate back to the IR sensor and the 20KHz modulated signal is given to the pin3 of LM567 through photo Darlington transistor, at this point the pin8 of the LM567 is turned to low and also gets locked to detect the 20Khz signal. By this the LM555 is turned low and disabled by this the led will remain lighting and buzzer makes the continuous sound to alert the driver.

Mount this car parking guard circuit at the back bumper and placed at the center. The piezobuzzer and LED indicator should be placed on the dashboard so the driver able to hear the sound alert clearly and can clearly see the indicator LED.

Make the connection to the reverse indicator light and the circuit in parallel and beware of the polarity (not to reserve).

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This is the circuit diagram of car audio system anti theft security which can be effectively used to protect and secure your expensive car audio system from stealing. This simple circuit designed based on popular CMOS NAND chip CD4093,.

When the circuit is switched on via switch S1, the indicator LED1 will glow and the circuit state will be in the standby mode. LED inside optocoupler IC1 is lit as the cathode terminal is connected through the car audio (amplifier) body. As a result, the output at pin 3 of gate N1 goes low and disables the rest of the circuit.

Whenever an attempt is made to remove the car audio from its mounting by cutting its connecting wires, the optocoupler immediately turns off, as its LED cathode terminal is hanging. As a result, the oscillator circuit built around gates N2 and N3 is activated and it manages the “on” / “off” timings of the relay via transistor T2. (Relay contacts can be used to energize an emergency beeper, indicator, car horns, etc, if desired.)

Change the values of capacitor C2 to get different “on” / “off” timings for relay RL1 to be “On” / “Off”. With 100uF we get about 5 seconds as “on” and 5 seconds as “off” time. You may make your own experiments as needed.

Gate N4, with its associated components, forms a self-testing circuit. Normally, both of its inputs are in “high” state. However, when one switches off the ignition key, the supply to the car audio is also disconnected. Thus the output of gate N4 jumps to a “high” state and it provides a differentiated short pulse to forward bias transistor T1 for a short duration. (The combination of capacitor C1 and resistor R5 serves as the differentiating circuit.)

As a result, the buzzer in the collector terminal of T1 beeps to announce for a short duration that the safety circuit is intact. This period of “on” ring can be varied by changing the values ​​of the capacitor C1 and / or resistor R5.

After construction, fix the LED and buzzer in dashboard as per your requirement and hide switch S1 in a in a convenient place. Then connect lead A to the body of car stereo (not to the body of vehicle) and lead B to its positive lead terminal. Take power supply for the circuit from the car battery directly.

Warning: This design is meant for car audios with negative ground only.

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Digital Tachometer Mainboard Scheme:

Digital Tachometer Front Display Scheme:

The digital RPM meter / tachometer comprises a motherboard and separate display board with a matching facia plate to provide a professional looking finish.

Digital Tachometer Specifications

• Range: 100 – 9900 revolutions/minute
• 2 digit display showing hundreds and Thousands of rPM’s (x100)
• Easy calibration
• Suitable for 2 and 4 stroke with Any number of cylinders
• Suitable for contact breaker or electronic ignition systems
• Contact breaker debounce circuit
• Resolution: 100 RPM
• Adjustable brightness
• Power supply: 10 – 15VDC / 200mA

The kit for this circuit is available, you may purchase the kit at quasarelectronics.co.uk.
Download the manual book about this circuit include the part list and how to assemble this circuit:

Digital RPM Meter_k2625

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Image #1: Car Anti Theft Guard Circuit Design Diagram

This is the circuit diagram of car anti-theft to protect and increase the security of your car, prevent your from stealing. This circuit is very simple, low cost and easy to built. When key-operated switch S2 of the car is turned on, 12V DC supply from the car battery is extended to the entire circuit through polarity-guard diode D5. Blinking LED1 flashes to indicate that the car protection circuit is enabled. It works off 12V power supply along with current-limiting resistor R4 in series.

When the car door is closed, door switch S1 is in “on” condition and 12V power supply is available across resistor R1. This condition will  prevent transistor T1 from conducting. In this position, anti-theft protection circuit is in sleep mode.

Image #2: Car Door Switch

When someone opens the car door, switch S1 becomes “off” as shown in Image #2. As a result, transistor T1 conducts to fire relay-driver SCR1 (BT169) after a short delay introduced by capacitor C1. Electromagnetic relay RL1 energises and its N/O contact connects the power supply to piezobuzzer PZ1, which starts beeping to indicate that someone is make a try to steal your car. To reset the circuit, turn off switch S2 using car key. This will cutoff the power supply to the circuit, so the buzzer sound will be stopped.

Collect the circuit on an universal PCB and house in a little box suit to your car. Connect the switch S1 to th ecar door and keep piezobuzzer Pz1 at a suitable place in your car.

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To calibrate the Tachometer circuit, set engines trimmer potentiometers R2 and R4 in the middle position. Turn on the power circuit and switch to the input rectangular pulses at 60 Hz from any generator. Rotate the resistor R2, select statements milliammeter equal 0.36 mA, equivalent to 3600. / Min. Disconnect the signal from the entrance, and trimmer R3 Achieve that the instrument showed a 0 mA. Reconnect the input signal is 60 Hz, and if the readings differ from the 0.36 mA, rotate the R4. Fully calibrated speedometer should read 0 mA at 0 Hz input and 0.36 mA at 60 Hz.

Tachometer schematic note :

• I did not test tachometer  schematic on any car. Installing it on the car, all the responsibility you take on.
• However, the signals from my function generator tachometer worked fine.
• The voltage on the high-voltage wire connector coming from the ignition coil reaches several kilovolts. When you connect the tach motor vehicle must be off. Do not handle the installation of a tachometer on a car if you do not have enough experience and knowledge of automotive electronics. I do not take any responsibility for accidents that can happen to you.
• For power Tachometer schematic circuits need a source of 12 V.
• Bridge rectifier D3 can be assembled from four diodes are 1N4007 .
• M1 – milliammeter pointer to the current full deflection of 1 mA.

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Car Horn Circuit Description:

This car horn circuit reproduces the sound of contemporary vehicle horns. It had been mainly created for models and toys but, applying a high output energy audio amplifier IC, it could be implemented as well in further complicated projects.
Circuit operation

To receive a realistic automobile horn sound, two different tones mixed collectively are essential and the interval they’ll type ought to be a so known as minor third (in musical terms). This can be implemented by two 7555 CMos Timer ICs wired as astable multivibrators and generating a square wave of about 440Hz and 523Hz respectively. These frequencies ought to be quite precise, so the uncommon values necessary for your timing resistors are obtained by wiring two common worth resistors in series.

The square wave frequencies produced by IC1 (440Hz) and IC2 (523Hz) are mixed via R5 and R6 and shaped by C3, C4 and R7 in order to obtain a far more realistic tone. The resulting composite audio signal is ultimately sent for the audio power amplifier IC3 which, in turn, drives the loudspeaker. R7 needs to be adjusted to acquire a satisfactory output level.

Car Horn Circuit Notes:

• The loudspeaker may be of any form and diameter. Certainly it need to withstand a energy of at the least 1 Watt if the TDA7052 Audio power amplifier IC is chosen.
• The TDA7052 IC was used since it permits a minimum parts count and very excellent functionality. Wanting to make use of a distinct audio power amplifier IC, you are able to pick the much less effective but straightforward to find LM386 (see the Cuckoo-song Generator project).
• In any case, try a great sized device, as a way to receive finest outcomes.
• Needing a a lot more effective amplifier chip, it is possible to use the TDA2003 10W Car Radio Audio Amplifier IC or the TDA1516BQ 24W BTL Vehicle Radio Power Amplifier IC .

Source: RedCircuits

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Components List:

D1,D2,D3,D4,D5,D6,D7 : 1N4148
D8,D9                : 1N4007
ZD1                  : 2V4
R1,R2,R3,R4          : 47K
R5                   : 220K
R6,R7                : 470
R8,R9                : 10K
R10                  : 1M
C1                   : 100nF
C2,C3,C4,C5,C6       : 22uF/16V
C7                   : 470uF/16V
T1                   : BC547B
IC1                  : CD40106
IC2                  : CD4070
Buz1                 : Buzzer

Car Headlight Alarm Features:

• Continuously repeated alarm tone for lights ON (may be disabled)
• Repeated alarm tone for lights OUT
• Only 3 wires are required for hook-up

This circuit come from Velleman product kit. Download the kit manual of Velleman car headlight alarm from the following link:

Car Headlight Alarm Circuit

1 file(s) 557.34 KB

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Circuit diagram:

Wiring diagram with the vehicles:

Circuit Notes:
This circuit used for cars with negative ground 12V negative ground system, maximum ignition current of 4A and maximum switching speed 500KHz. Motorcycles, mowers, boats, etc can also use this circuit.

For 6V Negative ground system, change the following resistors:

• R1, R2: 150 ohm / 1W
• R3 : 68 ohm / 1/4W
• R4 : 100 ohm / 1/4W
• R5, R6, R7: 68 ohm / 1W

Car Transistor Ignition Specifications :

• Completely shockproof
• Practically test on 2-4-6-8 cylinder engines during a total amount of 2.500.000 km.
• Principle: transistorized ignition
• Connection element: Darlington transistor, triple diffused
• Connection current: 4 A
• Connection speed : Up to 500 KHz
• Typical firing period : 2.000 u second

The kit of electronic transistor ignition is available at electronic online store. Download the manual transistor ignition kit manual from the following link:

Electronic Transistor Ignition For Cars

1 file(s) 329.59 KB

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