Circuit electrinic

Most cars do not have delayed interior lights. The circuit presented can put this right. It switches the interior lights of a car on and off gradually. This makes it a lot easier, for instance, to find the ignition keyhole when the lights have gone off after the car door has been closed. Since the circuit must be operated by the door switch, a slight intervention in the wiring of this switch is unavoidable. When the car door is opened, the door switch closes the lights circuit to earth. When the door is closed (and the switch is open), transistor T1, whose base is linked to the switch, cuts off T2, so that the interior light remains off. When the switch closes (when the door is opened), the base of T1 is at earth level and the transistor is off.

Capacitor C1 is charged fairly rapidly via R3 and D1, whereupon T2 comes on so that the interior light is switched on. When the door is closed again, T1 conducts and stops the charging of C1. However, the capacitor is discharged fairly slowly via R5, so that T2 is not turned off immediately. This ensures that the interior light remains on for a little while and then goes out slowly. The time delays may be varied quite substantially by altering the values of R3, R5, and C1. Circuit IC2 may be one of many types of n-channel power MOSFET, but it should be able to handle drain-source voltages greater than 50 V. In the proto-type, a BUZ74 is used which can handle D-S voltages of up to 500 V.

Here is a simple circuit that starts playing the car horn whenever your car is in reverse gear. The circuit (1) employs dual timer NE556 to generate the sound. One of the timers is wired as an astable multivibrator to generate the tone and the other is wired as a monostable multivibrator. Working of the circuit is simple. When the car is in reverse gear, reverse-gear switch S1 of the car gets shorted and the monostable timer triggers to give a high output. As a result, the junction of diodes D1 and D2 goes high for a few seconds depending on the time period developed through resistor R4 and capacitor C4.At this point, the astable multivibrator is enabled to start oscillating. The output of the astable multivibrator is fed to the speaker through capacitor C6.

Car reversing horn diagram:

Car Reversing Horn Circuit Diagram

The speaker, in turn, produces sound until the output of the monostable is high. When the junction of diodes D1 and D2 is low, the astable multivibrator is disabled to stop oscillating. The output of the astable multivibrator is fed to the speaker through capacitor C6. The speaker, in turn, does not produce sound. Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet.Connect the circuit to the car reverse switch through two wires such that S1 shorts when the car gear is reversed and is open otherwise. To power the circuit, use the car battery.

Flasher diagram:

Flasher Circuit Diagram

The flasher circuit (shown in Fig. 2) is built around timer NE555, which is wired as an astable multi-vibrator that outputs square wave at its pin 3. A 10W auto bulb is used for flasher. The flashing rate of the bulb is decided by preset VR1.
Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. The flasher bulb can be mounted at the car’s rear side in a reflector or a narrow painted suitable enclosure. EFY note. A higher-wattage bulb may reduce the intensity of the head-light. You can enclose both the car-reversing horn and flasher circuits together or separately in a cabinet in your car.

Author: Ashok K. Doctor - Copyright: Electronics For You Magazine

In recent years, car MP3 formed a fashion trend among the car owners, whether to buy a tape or CD disc at the past, there are the stored information. While you can download any music through the network needs to MP3, so MP3 become the cheapest and most convenient way to exchange music. Recently car, the MP3 car digital products is the highest sales growth in the auto parts market this year. But many products that is not good enough hurt the interests of consumers in the market.
It is understood that the last car audio market share of 80% dominated by the car CD discs, and 20% for the low-end car cassette machines occupied. Beginning last year, car MP3 owners are more and more popular, and gradually become the main alternative to car audio CD player. Comparing with CD ROM, the car MP3 can be unlimited downloads from the Internet the latest pop music, hence, have low cost, content and flexible, easy to update, and many other advantages.
According to the survey, car MP3 market is growing rapidly, but there has also been the phenomenon of cohabitation of product quality. Some manufacturers low price to win, resulting in uneven quality.
How to safeguard the interests of consumers and make the car MP3 healthy market development in the current chaotic car MP3 market situation? Industry believes that the functions of management and marketing managers should increase market management, prevent inferior products entering the market to regulate market and promote the healthy development the market. Meanwhile, in order to protect their own interests, consumers should shop around different car MP3 store.