This circuit diagram is a simple digital revolution counter. It can be used to count the rotation of a machine
like coil winding machine etc.
Mechanical part
It has two sections. One is the mechanical which converts the shaft rotation into clock pulses. Other one is an counter.
The details of the mechanical parts are shown in figure(2).
(1) Make mechanical part as showen in the figure(2)
(2) take a DVD or CD and put a drill hole (1cm diameter.) at outer periphery as shown in figure(2).
(3) Fix the disc in the shaft and enclose the whole things showen in the figure(2).
(4) Fix one white LED and a Photo diode (LDR) face to face on each side
Now the mechanical part is ready
Parts List
* CD 4026 ic = 4
* 7 Segment Display (common cathode ) = 4
* Photo diode (LDR) =1
* white LED =1
* C828 Transistor =1
* 2K = 1
* 50K V/R = 1
* 10K = 1
* 2K2 =1
* 9V Relay =1
