Reverse Killswitch

[mpsya]

Hi all.


I recently added a killswitch to my Strat (which works great) using this wiring diagram...


I now want to modify it to add the below reverse killswitch circuit that I found posted elsewhere on the forum by user bodsterbug (green labels added by me). The general principal is swapping the guitar's regular volume pot for a push/pull pot. Pulling the pot will turn the regular killswitch (push switch to cut the signal) into a reverse killswitch (signal cut until switch is pushed)...



Please could someone help me decipher the diagram? I have two questions:


1. I'm not sure what Lug B is connected to. The diagram, says Volume/Pickups but the pot in the diagram, is the Volume pot. My initial thoughts are that this is a typo and it should really read Selector switch/Pickups. Can anyone confirm this or otherwise?

2. The standard pot lugs (1 2 3) are not shown in the diagram. Should these therefore remain unconnected?

Any help would be greatly appreciated.

Thanks in advance.

[newey]

First thing that should be said is that, while the old diagram from bodsterbug will work, it leaves the pickup(s) "hanging from hot" when the P/P switch is pulled up (i.e., in the "push to play" position). This is not a deal-killer, but might introduce some noise. I said at the time (back in 2011) that a double-pole kill buttton would be needed- and if you want to eliminate the "hanging coil" issue, it would be.

Someone else recently brought up this same idea, having a "push to kill" and "push to play" button, with the option to switch between the two. But at the moment, I don't recall that particular thread.

Lug B is the "hot" input to this module. It might be coming from a pickup (e.g., as on a single pickup guitar with no selector switch), it might be coming from a pickup selector switch (e.g., as on an LP-type axe where the V and T controls come before the selector switch), or it might be coming from the volume pot, if a master V and T are being used. The pot lugs are simply omitted from the diagram entirely, since this is just a module for the killswitch switching, we don't know how the volume pot would be wired since we don't know the rest of the wiring scheme. And, the P/P switch might be on a tone pot- again, we don't know, but it's irrelevant to the module under discussion.

Your other post showed your Strat with the killswitch; if this mod is going to go into that guitar, with its master V and T controls, then Lug B would be wired off of the center lug of the volume pot, between the V pot and the ouput jack.

[mpsya]

Thank you very much for the detailed response. I think I understand.

It is indeed going in my master volume/master tone Strat. So if I replace the current Vol pot with the new p/p pot lug B just needs to be connected to centre lug on the pot itself?

I guess I'll just have to wait and see what the noise issue is like. Fingers crosed I get lucky with it. I'll have a look for the other thread you mentioned.

Thanks again

[ashcatlt]

Aug 26, 2020 14:40:16 GMT -5 newey said:

First thing that should be said is that, while the old diagram from bodsterbug will work, it leaves the pickup(s) "hanging from hot" when the P/P switch is pulled up (i.e., in the "push to play" position). This is not a deal-killer, but might introduce some noise. I said at the time (back in 2011) that a double-pole kill buttton would be needed- and if you want to eliminate the "hanging coil" issue, it would be.

There's no hanging coil. It leaves the jack open, which will probably be noisier than shorting it, but probably not as noisy as having a whole pickup coil hanging. I think the fix is the same, though, and yes would require that the kill switch itself be able to wired as either NC or NO.

That diagram is only showing the switch part of the thing. Wire the rest of the guitar any way you want, then put this in place of the connection to the jack.

[mpsya]

Thanks for the extra info ashcatlt All very helpful.

I'm finally getting round to putting this together today. I've just noticed that in the diagram the jack doesn't have a ground wire attached to it. Has this just been omitted for simplicity's sake or should I not connect the jack to ground?

Thanks in advance for any guidance.

[newey]

Sept 19, 2020 2:26:02 GMT -5 mpsya said:

I've just noticed that in the diagram the jack doesn't have a ground wire attached to it. Has this just been omitted for simplicity's sake or should I not connect the jack to ground?

Yes, it's just omitted as understood. The hand-drawn diagram just shows the "hot" side of the wiring, it also omits the pickup grounds

[mpsya]

Good stuff. Thanks for confirming.

[badatsoldering]

I am very new to all of this and need help understanding. Please excuse my lack of knowledge.

I am using a piezo element and it is running into a master volume.

When the dpdt (2 position) switch is set so that the spst switch is "push to play" I get very loud ground hum. When it is in the "push to cut" position, everything is nice and quiet.

I currently have terminal 6 from the dpdt and the Jack grounded to the volume pot.

Here is a very rough diagram (ground from jack + dpdt left out of drawing). I really appreciate any advice.

[newey]

bad-

Hello and Welcome to G-Nutz2!

If your guitar is wired as per your diagram, it should work as desired. If you are getting some output, but loud hum, in the "push to play" position, I suspect it is a bad connection somewhere.

First, look to see if there are any stray strands of wire that may be touching somewhere they shouldn't. If there is nothing obvious there, then next try hitting the solder connections to that half of the DPDT switch, and of the kill switch, with your soldering iron, enough to remelt the solder, then double check that you have good connection by tugging gently on the wires.

If that doesn't work, more detailed troubleshooting will probably be needed. When I said that maybe it is a fact of piezo pickups, I just mean that I have not heard of anyone ever trying to "ground out" a piezo signal to kill it. Since pizos produce signal differently than mag pickups, maybe that's an issue, I don't know