Hello AAC, I am hoping to get some help getting a 74193 counter IC working properly. After a momentary High is put on the clear pin, the Q-outputs will all go Low properly, but the Q-outputs do not increment in sequence, as they should. The binary count output varies; it will sometimes increment from a 1000 to a 0010, or from a 1000 to a 1100, and then to a 1110. I have a bunch of these 74193 counter ICs, and have used them before without problems, but now I'm having trouble. I'm not using the preset pins (I have them grounded). I have the load pin tied high, and a 555 Timer going to the count-up pin, (count-down pin is tied High). For now I was just trying to get it to count from 0000 to 1111. Thanks lots.

 

Hello AAC, I am hoping to get some help getting a 74193 counter IC working properly. After a momentary High is put on the clear pin, the Q-outputs will all go Low properly, but the Q-outputs do not increment in sequence, as they should. The binary count output varies; it will sometimes increment from a 1000 to a 0010, or from a 1000 to a 1100, and then to a 1110. I have a bunch of these 74193 counter ICs, and have used them before without problems, but now I'm having trouble. I'm not using the preset pins (I have them grounded). I have the load pin tied high, and a 555 Timer going to the count-up pin, (count-down pin is tied High). For now I was just trying to get it to count from 0000 to 1111. Thanks lots.

A schematic diagram would be more helpful than the written paragraph. It sounds like an unconnected input(s), ragged transitions, or bouncing on the clock pin. Are you absolutely certain that the 555 is maintaining proper TTL voltage levels with clean high to low and low to high transitions? Counter chips are incredibly sensitive to such things.

 

Put a 10μF electrolytic capacitor as close as possible across the Vcc and GND pins of the 555 timer IC.
Put a 0.1μF ceramic disc capacitor as close as possible across the Vcc and GND pins of the 74193 counter IC.

 

There is no way to diagnose a circuit problem without the circuit. It's right there in the title of this site.

Paraphrasing Rear Admiral Joshua Painter,

"Engineers don't take a dump, son, without a schematic."

ak

 

A schematic diagram would be more helpful than the written paragraph. It sounds like an unconnected input(s), ragged transitions, or bouncing on the clock pin. Are you absolutely certain that the 555 is maintaining proper TTL voltage levels with clean high to low and low to high transitions? Counter chips are incredibly sensitive to such things.

I concur with PapaB. It sounds like an undefined input, or possibly a noise burst instead of a pulse, or both.

 

I have a bunch of these 74193 counter ICs, and have used them before without problems, but now I'm having trouble.

Have you tried using the misbehaving counters in a circuit that is known to be working? Or vice versa?

 

At one time the diagnosis would have been that it was a T.I. IC socket. They were notorious for poor connections. IN the past.