Presetable rep counter with bell at 0

[jrowe]

I am trying to add a rep counter using 3 7 segment displays to my home gym. I want to be able to preset the number of reps and have it count down with a bell/buzzer at the end. I am putting detect switches on my equipment to detect the rep. All of the circuits I can find with presets count down seconds not button pushes. Does anyone have a circuit to do that?

 

[MikeMl]

What kind of switch?
Two connections (normally open or normally closed) or Three (normally open/normally closed/common)?

 

[jrowe]

switches

Regular N/O push button or magnetic switches.

 

[MikeMl]

Regular N/O push button or magnetic switches.

Ok, that requires a robust debounce circuit to eliminate multiple down counts.

Your counter circuit probably uses a 555 as a clock source. You can substitute this circuit for whatever your counter uses as a clock. I simulated extra pulses which may or may not come from your switch to make sure that this circuit eliminates the multiple edges...

 

[jrowe]

Countdown circuit

None of the circuits I have found were able to be modified by my limited knowledge. I know about enough to get myself shocked when I touch the wrong pin.

I have a 555 on shot timer circuit that I am using to fire the counter. It's the counter circuit itself that I need.

 

[MikeMl]

I'm confused. Do you have a presettable counter circuit which counts down by seconds? If so, disconnect the clock source (1Hz pulse) and replace it with the "Count" pulse in the circuit I posted above.

Also, why build the counter when you can buy one?

 

[tytower]

Also, why build the counter when you can buy one?

Oh man ,there goes the do it yourself initiative . Just go buy it ...not me.

 

[jrowe]

Rep counter

No I don't have one, I found a couple that wasn't very good and I couldn't figure out how to modify them so I moved on. I have typed so many things in to google I can't remember where I found them at. That's why I am posting here, it looked like one of the best forums during my search for the needle in the haystack.

What I need is a rep counter I can preset a number(3 digit) in, have it count down and trigger a relay at 0. I have a 555 one shot timer that I am hooking up to limit switches for the trigger but all of the counting circuits I can find (that I can understand)only go up with no preset and relay. I was hoping that someone had done something similar and could hook me up with a schematic.

 

[jrowe]

Also, why build the counter when you can buy one?

The bigger question is why pay $200 for one I can build for less the $20?

 

[jrowe]

Rep Counter

shameless bump