NoOneYouKnow
Member
OK, well I've posted about this a few times, and I've gotten it working, but I'm having a problem with two things.
1. Accuracy of the pulses.
2. Random counting.
Here's the circuit.
**broken link removed**
The monostable side of the 555 should trigger for 435ms, allowing 3 pulses from the astable side to activate the counter. I've having a few problems though.
I know the 555 formulas to figure out the parts to use to achieve 435ms, but it's not accurate enough. Some times it lets 2 pulses through, sometimes as many as 5 make it through. I need this to be 3, every time. SO, could someone possibly recommend some high accuracy parts to achieve what I need? The average resistors and caps from Mouser have too high tolerances to be accurate enough.
For the second problem, it jumps to random numbers. Pressing the "Reload" button sets the counter to 36. Every time I press the "Trigger", it should count-down by 3. This normally works, though it's sometimes 4. However, if I hold the "Trigger" button just right when I push it, it counts down three then jumps again or all the way to 99. I assume this has something to do with micro-arching in the switch causing ripples in the circuit. Any ideas to fix this?
Also, it seems to get dramatically more errors when the four LEDs are plugged in. Any ways to fix this?
1. Accuracy of the pulses.
2. Random counting.
Here's the circuit.
**broken link removed**
The monostable side of the 555 should trigger for 435ms, allowing 3 pulses from the astable side to activate the counter. I've having a few problems though.
I know the 555 formulas to figure out the parts to use to achieve 435ms, but it's not accurate enough. Some times it lets 2 pulses through, sometimes as many as 5 make it through. I need this to be 3, every time. SO, could someone possibly recommend some high accuracy parts to achieve what I need? The average resistors and caps from Mouser have too high tolerances to be accurate enough.
For the second problem, it jumps to random numbers. Pressing the "Reload" button sets the counter to 36. Every time I press the "Trigger", it should count-down by 3. This normally works, though it's sometimes 4. However, if I hold the "Trigger" button just right when I push it, it counts down three then jumps again or all the way to 99. I assume this has something to do with micro-arching in the switch causing ripples in the circuit. Any ideas to fix this?
Also, it seems to get dramatically more errors when the four LEDs are plugged in. Any ways to fix this?
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