Can I do this with a switch?

Started by jimosity, May 08, 2012, 08:15:21 AM

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jimosity

What I want to be able to do is simulate two momentary pulses; but with one latching switch.
Is there a way to do this so that when I step on a latching switch it sort of does the same as if a momentary switch was pressed twice?
Or if it can be done with a momentary switch, that'd be cool too (without actually doing it twice is the key)
Jim Rodgers
jim@americanhc.com

Earthscum

I only have 5 minutes before I gotta leave for work, but I had come up with a possible way (actually, if I had time to find the notes, I think I actually tested it and it worked). It used a schmitt trigger IC. I had made it to generate a 50mS pulse off of the ON and OFF of a momentary SPST for the old MV-52 tap tempo. Molten Voltage told me to hold off for a bit designing for that chip, and popped out the MV-52 (which I gotta get me one to play with... fun and super simple), so it's been awhile since I've looked at it.

If nobody else gets to it by this evening, I'll dig out what I have for you if you're interested (I'm interested to see an easier way, in the meantime, lol). Should be 3 of the 6 ST's, so you'll have 3 others for buffering LED or whatever (maybe it uses 4 and 2 extra for LED...).
Give a man Fuzz, and he'll jam for a day... teach a man how to make a Fuzz and he'll never jam again!

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~arph

#2
If the timing of the two pulses isn't too critical you can do it with a momentary switch, one resistor, one capacitor and one two input XOR gate. (4070). Switch needs debouncing though.. so an extra res and cap is required for that.

Take the debounced switch output, feed it into one input of the XOR..  Take the same output, feed it into a resistor and then a cap to ground. and the junction of those to the other input of the XOR, so it sees a slightly delayed input signal.  The XOR will produce a pulse on the rising and falling edge. Done.

The pulse width can be set by changing the resistor/cap at the XOR input..


Earthscum

#3
Just got to work and thought of something... what is your latching switch going to be doing? If you are routing signal through it, then you will have stuff hanging off that will affect either circuit, but if you're using it to control, for instance, a High or Low signal, then that would work find to create pulses off of.

It's actually pretty easy, just logic thinking. Decide what you want to do, and start putting common blocks together. If we know what the mechanical switch is doing, then  we can decide on how to use it to control the pulses. You could create a pulse just by breaking and touching ground (momentary normally closed), or the opposite (with momentary n/o), create a pulse each time a pole touches a ground OR a certain voltage, or when that connection is broken.

To paraphrase an idea R.G. got stuck in my head... There's a hundred ways to beat a dead horse, you just gotta pick your stick.
Give a man Fuzz, and he'll jam for a day... teach a man how to make a Fuzz and he'll never jam again!

http://www.facebook.com/Earthscum

jimosity

It's not passing audio, just controlling a state.
One momentary push chooses one state.
Two momentary pushes chooses another state.

I'd like to be able to press one switch (momentary) to get the first state.
But, I'd like to have a second switch that can be pressed once and do the equivalent of two momentary presses.

Timing isn't too critical within reason...thinking in terms of how long it would take the human foot to press a momentary switch twice and that's about the timing I'm looking for.
Jim Rodgers
jim@americanhc.com

Earthscum

You may give this a try. I'd try 100k's on all the resistors and 47n to 10n on the caps. S1 is your single pulse, S2 is your double pulse, pulses once when you press, and pulses a second time when you release.

Give a man Fuzz, and he'll jam for a day... teach a man how to make a Fuzz and he'll never jam again!

http://www.facebook.com/Earthscum

jimosity

Thanks man, I guess I need to get a schmitt trigger ic to test...
Jim Rodgers
jim@americanhc.com