Rev Counter not counting correctly.

[Impulse]

I've built a basic counter module with 3 LED displays, It works, but I have coupled it to a photo interrupter so that i can count revolutions. Now it seems to jump 5 to 10 places per revolution. I'm guessing there must be spikes in the signal coming from the photo interrupter. Does anyone have any suggestions to making this more stable?

 

[audioguru]

Maybe interference from ambient light or radiated heat?
Did you use a shielded cable for the light sensor?

 

[jbeng]

A schematic diagram of your circuit would help us to help you ...
JB

 

[Impulse]

Schematic

Here is a basic schematic of the system.

 

[ljcox]

I suggest you insert a low pass filter followed by a Schmitt Trigger IC such as the 74LS14 in the signal line.

I''ll try to draw a diagram

Collector of NPN transistor------resistor-----A-----Schmitt Trigger-------> U2/5

Connect the capacitor from A to gnd.

Len

 

[Impulse]

Thanks Len,

Its taken me a while to tested it out, but it worked like a charm!!!

Wes

 

[ljcox]

You're welcome

Len