One-shot

Fire a single pulse on the rising edge, then stop — even if you hold the input. A ready-made counters circuit you can open in the TorchAnvil simulator.

A pulse on every rising edge

A lever held on is always on. But sometimes you don't want "on" — you want the moment something switched on. A one-shot (also called a monostable) gives you exactly that: a single brief flash every time its input transitions from low to high.

Press Run and flip the lever on. The lamp blinks for one tick and then goes dark, even though the lever is still on. Flip it off and on again — another single blink.

How it works

The trick is to compare now with a moment ago:

• Lever → AND.in-0 — the current input.
• Lever → Delayer (1 tick) → NOT → AND.in-1 — the input as it was one tick ago, inverted.

The AND only fires when the present is high and the past was low — which is the definition of a rising edge.

out = In and not delayed(In)

tick	In	delayed In	NOT(delayed In)	out (Lamp)
0	0	0	1	0
1	1	0	1	1 (fire!)
2	1	1	0	0
3	1	1	0	0
4	0	1	0	0
5	0	0	1	0

Why it matters

This is the hardware equivalent of listening for "the moment you pressed the button" instead of "while you're pressing the button." It's the heart of debouncers, single-step controls, trigger generators, and any circuit that needs to advance one step per press regardless of how long the press lasts. Every CPU's instruction-fetch logic has cousins of this pattern scattered through it.

Try this

• Press Run, flip the lever on, and hold it. The lamp flashes once and stays dark. That's the "one-shot" — one flash, no more.
• Flip it off and on again. Another single flash.
• Increase delayTicks on the delayer to 2 or 3. The pulse width grows to match — so the "one shot" fires for that many ticks each edge.