4510 tachometer not working

Thread Starter


Joined May 30, 2022
I have a 4510 counter circuit that is used as a tachometer, the problem is that it counts up way too fast, with one pass of the finger through the ir led and phototransistor it counts up by a 100, when the cable from the clock is disconnected from the irled it counts very fast, it also only counts in odd numbers on some and even on the others. the schematic of the circuit and the connection is as follows:20220530_225356.jpg20220527_135458.jpg20220530_225631.jpg


Joined Oct 2, 2009
You have failed to include power supply decoupling capacitors in your design and breadboard.
On a PCB layout it is good engineering practice to place one 0.1μF ceramic disc capacitor between Vcc and GND at every IC as close to the Vcc and GND pins as possible, keeping the capacitor leads and traces as short as possible.


Joined Nov 6, 2012
What are You doing about "Signal-Conditioning" the Output of your IR-Detector ?
( Hysteresis ) ( Switching-Speed ) ( "Off" Voltage-Level vs "On" Voltage-Level )

What is the fastest number of counts-per-second that You want to count ?