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Automotive Alarm Circuits
Car Lighting Circuits
Car Parking Aid Circuits
Car Audio Circuits
Car Bike Circuits
A unijunction transistor audio oscillator drives a small speaker. The oscillator"s frequency is determined by resistor R2 and capacitor C2. The ope rating voltage is supplied from the car"s turn-signal circuit(s) through Dl and D2.
When the driver depresses pushbutton switch S1, timing capacitor C1 charges to 12 V and turns on transistor Q1, which drives power transistor Q2 into conduction. This, in tum, energizes the relay which has its contacts connected in parallel with the headlight switch. The relay will stay energized unW C1 discharges to the Q1 tum-off level. The...
An LM556 dual oscillator/timer, U1, configured as a two-tone oscillator drives U2, a dual4-watt amplifier. One of the oscillators, pins 1 to 6, contained in U1 produces the upper frequency signal of about 200 Hz, while the second oscillator, pins 8 to 13, provides the lower frequency signal of about 140Hz. Increase or decrease the frequencies...
The circuit keeps the courtesy light on for 30 seconds after you close the door. The lead from the door switch is removed and connected to the 555 circuit. The 555 is arranged in a monostable mode, and is triggered by the door switches. The output drives Ql, which is connected across the interior light switch. The interior light is turned on...
When power is first applied, three things happen: light -driving transistor Ql is switched on due to a iow output from U2 pin 3; timer U1 begins its timing cycle, with the output, pin 3, becoming high, inhibiting U2"s trigger, pin 2, via D2; and charge current begins to move through R3 and R4 to Cl. When Ul"s output becomes low, the...
The base of Ql is connected to the car"s ignition circuit. One side of the piezoelectric buzzer is connected to the instrument-panellight fuse. When the headlights are off,. no current reaches the buzzer, and therefore nothing happens. What happens when the headlights are on depends on the state of the ignition switch. When the ignition...
Digital Oil-Pressure Gauge
This gauge uses a sensor in conjunction with R1 to develop a dc voltage proportional to oil pressure. IC1 and IC
Automotive Electrical Tester
This little tester is useful for checking vehicle electrical circuits. Two LEDs indicate whether one of the cl
Digital Vacuum Gauge
A bridge circuit is used to produce a signal from the output of vacuum sensor IC1. IC2b provides about a 0.2 V offset
Digital Fuel Gauge
This circuit uses a digital voltmeter (formed from IC1 and IC3) to display fuel quantity as a percentage of a full tank.
Digital Pressure Gauge
Using an intersil ICL 7106 A/D converter chip and an LED display module, this gauge uses a Sensym Corp. pressure tra
This circuit uses an RCA CA3162E (IC2) A/D converter. This converter has 12-bit output (BCD) which is sent to display decoder
Automatic Arming Auto Alarm
The circuit automatically turns on when the car is turned off. It gives you a variable time to get out and lock
SI is external key switch. The alarm allows a 0- to 45-s delay after SI is operated before the circuit is armed. During this per
Auto Ignition Cut-Off
Using an SCR/relay combination, this circuit can be made to cut off ignition, unless a positive voltage is applied to
Automatic Turn-Off Alarm With Delay
In this circuit, IC1A and IC1B act as a monostable multivibrator. Any input from the sensors SI through
With a single IC, you can build a simple, reliable auto burglar alarm or a similar alarm. See (a) for the timing informatio
Car Lights Monitor
This circuit is for the purpose of monitoring automotive lighting. Two special ICs are available from Telefunken that ar
Rear Fog Light Controller With Delay
We assume that most of our readers are thoughtful drivers who do not switch on their rear fog lights w
Third Brake Light
The circuit is designed to light (via SCR1 and SCR2) only when both the left and right brake lights are activated. The ci
Because power for the circuit is obtained from the car"s side lights, the circuit can"t oscillate unless the lights are o
Car Headlight Control
It is annoying to realize that you have left your car headlights on only to find that the battery is flat. One possib
Night Safety Light For Autos
This circuit turns on the brake lights of a parked car when the headlights of an oncoming car are detected, wa
Automobile Lights-On Reminder
The circuit can be used to give a visible or an audible warning that the headlights are on. It uses a 2N1305
Solid-State Windshield-Wiper Delay
In the wiper-delay schematic shown, with the ignition on, Dl maintains regulated +12 Vdc. When SI closes
This electronic ignition circuit is intended to be inserted into a car"s conventional ignition system. In effect, it re
High-Power Car Audio Amplifier
NOTE: FOR BRIDGE CONFIGURATION: t install jumpers ju2 and ju4 2.remove j 1)3 3.remove rio 4replace
Windshield Wiper Interval Controller
The windshield wiper interval circuit presented here is very compact and is noteworthy for its use of
Cd Ignition System For Autos Circuit
At the heart of the CD4-MX is an astable multivibrator, built around Q1 and Q2, that feeds step-up transformer Tl. The output of 1 is rectified by D3 to D6 and used to charge capacitor C4. When the points close, a small voltage is fed to the gate of SCR1, causing it to fire, dumping the charge of C4 to the vehicle`s ignition coil. The circuit...
Smart Turn Signal Circuit
STS schematic. The Q2 gate voltage increases with the charge on C3. After 15 seconds of charging, the buzzer will warble. As the charging continues, the sound will grow louder.Circuit waveforms. Point A shows the signal from the flasher. The voltage at point D will increase as long as the pin-3 output of IC1 (point C) remains high. The C1-R2...
Flashing Brake Light Circuit
When power is first applied, three things happen: the light-driving transistor (Ql) is switched on because of a low output from U2, pin 3; timer Ul begins its timing cycle, with the output (pin 3) going high, inhibiting U2`s trigger (pin 2) via D2; and charge current begins to move through R3 and R4 to CI.When Ul`s output goes low, the...
Booster Amplifier For Car Stereo Use Circuit
Only one channel of this circuit is shown. The other is practically a carbon copy.The input to the circuit, taken from your car radio`s speaker output, is divided along two paths; in one path, a high-power divider network (consisting of R8 through R10) provides 4.5- resistance to make the circuit`s input impedance compatible with the output...
Ultrasonic distance finder circuit
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
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