Petrol Gas Switch For A Vehicle

The bellow circuit is a petrol, gas switch for a Vehicle. As we know most of the vehicle, was modified for dual fuel -ie, petrol and gas. However, its necessary to run the vehicle on petrol at regular intervals to stop the injection from clogging up. This simple circuit allows the vehicle to be started using petrol and then automatically switches it to gas when the speed exceeds 45km/h and the brake pedal is pressed. Alternatively, the vehicle may be run on petrol simply by switching the existing petrol/gas switch to petrol. You can also start the vehicle on gas by pressing the brake pedal while starting the vehicle. The circuit is based on an LM324 dual op amp, with both op amps wired as comparators. It works like this : IC1a buffer the signal from the vehicles speed sensor and drives an output filter network (D1,a 560kohm resistor and a 10uF capacitor) to produce a Dc voltage that's proportional to the vehicles speed.

 

 Circuit Diagram :

 

 

 

 

This voltage is then applied to pin 5 of IC1b and compared with the voltage set by trim pot VR1.When pin 7 of IC1b goes high, transistor Q1 turns on. This also turns on transistor Q2 when the brake pedal is pressed (pressing the brake pedal applies +12V from the brake light circuit to Q2 emitter). And when Q2 turns on, relay1 turns on and its contacts switch to the gas position. Trim pot VR1 must be adjusted so that IC1b pin 7 output switches high when the desired trigger speed is reached (ie, 45km/h). In effect the speed signal is Ended with the brake light signal to turn on the relay. The vehicle has been running this circuit for several year now and is still running well, with no further injector cleans required.