Double throw momentary switch question

Hi,

Can anybody tell me a simple way to tweak a simple latch circuit to change state when the button is pressed in quick succession (say within

The schematic I've been working off is second circuit down at,

Would really appreciate any advice,

Hal.

It needs to change state every time it is double clicked.

I need to be using a momentary switch which will eventually be substituted with a vibration sensor.

The sensor on its own gives lots of outputs as per your first example. When in the latch schematic I mentioned in my original post it is debounced slightly so it acts more like your second example.

The ultimate idea is to have a circuit which toggles on or off when the sensor picks up a double knock in quick succession on a surface (exactly like a double knock on a door).

Thanks a lot John - I'm really grateful. It all seems very clear.

I might need a little help on the timing values though. Any two knocks in 1 second and 2 seconds between knocks seems about what I need.

On Sunday 26 September 2004 10:32 am, Hal Leemux did deign to grace us with the following:

Learn how to do this, and for version 2 you can make your secret knock, "Shave and a haircut, six bucks!"

Cheers! Rich

Maybe I've missed a crucial post, but the requirement still seems ill-defined to me?

There seem several facts not yet specified, such as:

1. What frequency is vibration?
2. What is voltage supply
3. Will vibration sensor signal have full amplitude of voltage supply?
4. If we call the period of vibration a 'knock', how long can each knock be?
5. Should that matter?
6. Should a *very* brief knock (possibly due to an accidental or premature, or just external noise) count?
7. What happens with say 3 successive knocks within 1 s? etc, etc.

I've tried to illustrate these in

Turning to the circuit, assuming we can tighten up the spec along the lines above, intuition says a much simpler approach than John's ought to be possible. (Although I haven't got one to offer .)

Thanks, that's clarified it nicely for me. Look forward to seeing the circuit.

Your summary also helped crystallise this question to the OP: why not simplify and toggle with *one* (significant) knock? By definition, you're going to get a toggle with 2, 3, 4 or maybe even more rapid knocks, so why single out 1 for exclusion?

Here's an alternative implementation of John's design.

Let me know if you have queries, or want to see simulated waveforms.

I'll also post a copy of this in a.b.s.e.

Thanks for your help Terry. I'll let you know how I get on.

Hal.