DS

Automatic switch-on when it gets dark, 6V or 3V battery operation This design was primarily intended to allow automatic switch-on of push-bike lights when it gets dark. Obviously, it can be used for any other purpose involving one or more lamps to be switched on and off depending of light intensity. Power can be supplied by any type of battery suitable to be fitted in your bike and having a voltage in the 3 to 6 Volts range. The Photo resistor R1 should be fitted into the box containing the complete circuit, but a hole should be made in a convenient side of the box to allow the light hitting the sensor. Trim R2 until the desired switching threshold is reached. The setup will require some experimenting, but it should not be difficult. Circuit diagram: Push-Bike Light Circuit Diagram Parts: R1_____________Photo resistor (any type) R2______________22K 1/2W Trimmer Cermet or Carbon type R3_______________1K 1/4W Resistor R4_______________2K7 1/4W Resistor R5_____________330R 1/4W Resistor (...

This is the simple tachometer for bikes uses 2 reed switches to urge the speed data of the bicycle. The reed switches are put in close to the rim of the wheel where permanent magnets pass by. The permanent magnets are connected to the wheelspokes and activate the reed switches everytime they pass by it. The speed is digitally displayed. The tachometer circuit works in step with this principle; the pulses created by the reed contacts are counted inside an explicit time interval. The ensuing count is then displayed and represents the speed of the bike. 2 4026 ICs are used to count the pulses, decode the counter and management 2 7-segment LED show. RS flip-flops U3 and U4 perform as anti-bounce. Electronic bicycle SP tachometer circuit diagram The pulses arrive at the counter’s input through gate U7. The measuring amount is set by monostable multivibrator U5/U6 and might be adjusted through potentiometer P1 so the tacho are often calibrated. The circuit U1/U2 resets the counters. Since ba...