Head Light

RF Transmitter

The FM transmitter is working on 27 Mhz is used to inform the speed breaker within 10 meter .It based on DTMF (dual tone multi frequency).

The DTMF generate various types of tones the tones are modulated in modulator section after amplification by the RF section is radiated by the antenna Transistor BC 494 are used for RF amp and modulator .

RECEIVER

The modulated signals are received by the antenna is fed to the FM receiver (27 Mhz),after de coded by the DTMF de coder is send to the appropriate driver section for activate the motor IC 8870 is used as DTMF de coder and all twelve transistor are working as driver to drive the motor

FEATURES

1 It can be controlled the speed of the car

2 The distance is 10 feet

3 It can be used for accident preventer

Components list

IC 91215 1

IC 8870 1

Tr BC 494 2

Tr bc 147 12

Res various types 15

X –tal 27 MHZ 2

Working

As shown in the circuit diagram, the transistor SL 100 is working as switching the relay. When there is no light the LDR gets high resistance and the transistor is in reverse bias condition, and the bulb gets ON. When light falls on the LDR, it goes low value of resistor and the transistor gets forward bias and it energise the relay and it switched off the bulb. The resistance 10 K, 180 ohm provide negative bias to the transistor. The base voltage can be set by the variable resistor 50K.

Components list

1. Transistor – SL-100 NPN ---- 1

2. Non polarized relay – 5V ---- 1

3. LDR ( light dependent resistance ) ----1

4. Variable resistance – 50K ----1

5. Resistance – 10K ----1

6. Resistance –180 ohm ----1

7. Transformer step down – 12-0-12 ----1

8. Diode – IN-4007 ----1

9. capacitor – 100 micro farad, 36V --- 1

10. Bulb – ---1