Momentary effect with latching switch?

[Ben N]

I did a search and there was a thread on physically modifying a switch--that's not what I am after.  What I am asking is whether there is a way to electronically (and reasonably simply) get the effect of a momentary switch from a latching switch--kind of like a flip-flop in reverse, so that each change in the state of the mechanical switch shows an identical momentary closed state to the circuit.

Why?  Because I have this Nobels PH-D phaser (4-stage 3080-based, very teakable but noisy) that has a jack for a remote momentary footswitch (as do several Boss pedals), and it got me to thinking that it might be useful to be able to "slave" the thing to a fuzzbox, say.  I imagine that is pretty simple to do if the other box is also an FET switcher, but I would like to do it with, say, a TBP box using the LED pole of a 3PDT.

Thanks for your thoughts.

Ben

[cd]

Yup.  Turn a DPDT or SPDT into a SPST momentary latch - use the common lug as one end, and tie the two alternate lugs together and use it as the other end.

Just in case it's not clear, there's a split second between the change from one end to the other - a "moment" if you will - that's what you're doing in this case.

[Ben N]

Very interesting, cd!

But wouldn't that be a closed circuit except for the split second?  As opposed to a momentary, which is normally open?  Would that work?

Ben

[Narcosynthesis]

i know if you use a latching switch in place of a momentary one, you have to stomp the switch twice to make it change

does that help at all?

Davud

[R.G.]

cd is correct, this works for all break-before-make switches, which all the stomp switches I have ever seen are. You generally have to pay extra to get make-before-break switches, which do exist. I first saw this in Kevin O'Connor's "The Ultimate Tone".

But wouldn't that be a closed circuit except for the split second? As opposed to a momentary, which is normally open? Would that work?

Momentary switches come in both normally open and normally closed. You can also get a SPDT momentary that has one NO and one NC throw.

Whether this is a problem to you or not depends on what you're doing with the switch. Many momentary switch applications will work fine on the single-pulse that you get from this switch, as you get one open and one close on each actuation, and many circuits look only for an open or a close.

But there is no substitute for knowing what the circuit actually does to know whether it will work OK or whether it needs more massaging to work.

[Transmogrifox]

I know you take the risk of wasting a little time, but just try it and see if it works.  Then start digging a little deeper if you must.

[Ben N]

Thanks, guys--will do!

Ben

[Mark Hammer]

GAHHHHH!!!  Another brainstorm.

Imagine the following.  You have a bunch of FET-switched pedals with external switching jacks (these could be Nobels, Boss, DOD, Yamaha, etc.).  The external switch, is of course, a momentary low resistance path to ground.  HOW that path goes low, however, is its own private business.

What this permits us to do is use FETs to provide that low (or high) resistance path.  Such FETs can, in turn, be ganged together to turn on (and off) multiple pedals in response to a common control signal.  What makes this kind of nifty is that the control signal COULD be the output of an envelope-follower/trigger-extracter.

Dig it.  You hit a power chord, and your pedals switch.  What's even neater is that since such pedals are flip-flop based, the external trigger simply reverses the current state of the pedal, whether that state was bypass or effect.  That means you can hit a chord, and turn some things off and others on.  How cool and automated is that?

My head is spinning.

[cd]

I first saw this in Kevin O'Connor's "The Ultimate Tone".

Yup, that's exactly where I saw it too  

To Mark Hammer: if you want to get really wild on the switching thing, you must get a copy of TUT if you haven't already.  The books is ostensibly about amps, but 1/4 of it is on switching methods alone.

[David]

MAN! Sometimes the Search function strikes gold -- like with this thread!

I need to come up with a way to get a U2 sort of echo-heavy tone.  The tools I have to work with are a Boss GT-3 digital processor and an Alesis NanoVerb.  I have an outboard latching SPST footswitch set up to select/deselect the delay.  The NanoVerb, unfortunately, just HAS to be different!  It requires a momentary footswitch -- which my good buddy CD has described how to make!!!!!!!!!!!!!

Here's what I'd like to try.  I could substitute one of those 3PDTs that Aron sells for the SPST footswitch that controls the delay.   I could use one set of terminals to handle the SPST latching functionality for the GT-3.  I could use another set of terminals to turn on an indicator LED when the SPST is engaged.  The final set of terminals would become CD's momentary workalike.  BOOM.  Latching and momentary functions selected/deselected by the same bloody stompswitch.  Oh, I-hope-I-hope-I-hope  those switches are break-before-make!!!!!

Any thoughts out there about whether this will work as described, or did I (typically) miss something crucial?

[dontbreakit]

this thread is gold among the ruins of the internet!

i have a boss noise suppressor (basically a gate with some minor threshold/decay leeway).
the switch is of course latching. i want to turn it into a momentary switch so that it is muted or gated when it is NOT pressed down, and sound is allowed through unmodified when it IS pressed.

can i use the same trick mentioned above?

Turn a DPDT or SPDT into a SPST momentary latch - use the common lug as one end, and tie the two alternate lugs together and use it as the other end.

or do i need to replace the switch with a different kind?

schematic:   http://obrazki.elektroda.net/47_1279571553.jpg

any help appreciated bigtime.

[Seljer]

Hmm, I'll add my experience to this thread.

I have a Roland Cube which wants a momentary footswitch for the channel switching. It switches on the transition from closed to open. If you use a regular momentary footswitch you have to hit it twice for it to change channels.

I tried connecting the outer terminals on three momentary switches (a blue one, an alpha DPDT and a carling SPDT) and they all switch too fast for the amp's switching circuit to catch the brief moment when the switch is in the air. It does however function with a regular rocker switch providing you don't hit it too quickly so there is merit to this 'hack' (just not with my amp )

[DiscoVlad]

I have a Roland Cube which wants a momentary footswitch for the channel switching. It switches on the transition from closed to open. If you use a regular momentary footswitch you have to hit it twice for it to change channels.

I've got one of these amps too...

In this case you could use some logic to invert the switch, and an optocoupler to act as the switch element - This is what the Boss FS-6 switch that Roland recommend for their amps does.