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Oct 14, 2020 16:32:10 GMT -5
Post by ashcatlt on Oct 14, 2020 16:32:10 GMT -5
Yeah I’m sorry to say you’re going to need another pole. I mean you might could work out some sort of active switching arrangement, but it can be tough to do that well.
Do you really really need it to be S/P? Could you live with a coil split instead?
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Oct 14, 2020 22:45:44 GMT -5
Post by sumgai on Oct 14, 2020 22:45:44 GMT -5
Another thought I've had is to try and build 2 DPDT switches into a 4PDT and attach it to the push/push pot. Fender's S1 switch is a 4PDT push/push unit. As to the rest of your request, we'd need to see a diagram of what you have, or at least what you're attempting to hook up. But without that diagram, I'm gonna go out on a limb and take a wild guess that you're a likely candidate for an Eyb M4 Megaswitch, which has 8 poles. Kinda costly, but if does the job..... Bingle is your friend here. HTH sumgai
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Oct 15, 2020 2:48:11 GMT -5
Post by asmith on Oct 15, 2020 2:48:11 GMT -5
+1 on asking for the rest of the circuit. Can those two wires' "disconnection" actually just be shorting both to ground? In which case you can do it with a 2P2T push-pull pot: EDIT: DON'T LISTEN TO ME I CAN'T READ
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Oct 15, 2020 5:45:48 GMT -5
Post by Yogi B on Oct 15, 2020 5:45:48 GMT -5
+1 on asking for the rest of the circuit. Can those two wires' "disconnection" actually just be shorting both to ground? Reading the OP, the disconnection should happen in the parallel mode, not series (which is when your diagram grounds the wires). But that leads me to think: 'disconnect' instead via pulling the gate of a p-JFET (that is otherwise pulled up to 9V) down to ground?? But again, the suitability of such is highly dependent on the circuit in question.
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Oct 15, 2020 9:50:41 GMT -5
Post by ashcatlt on Oct 15, 2020 9:50:41 GMT -5
Adding poles to the 5-way doesn’t help.
I’m totally guessing, but kind of educatedly, that the two wires from the boost circuit connect to either end of the feedback resistor in a non-inverting opamp configuration. When they are connected, they short that resistor and force it to unity gain. Not so much turning it off as changing into a no-boost buffer. Connecting one or both to ground will do the opposite - force the opamp to its full maximum open loop gain. That could be fun for a couple of minutes assuming the whole thing doesn’t just go to one of the rails and stay there, but not at all what the OP is looking for.
With four poles on the push/push, you’d have two for the S/P thing, one for the boost thing, and another for your “anit-icepick” load resistor, and everything would be cool. If that Fender part does it, then it really is what you want.
Course you never answered my question about the coil split...
Edit - Wait. You’re most recent post adds a wrinkle. Maybe I missed it in the original, but... If you want the bridge to always be in local parallel in position 4, and the push/push only active at 5, then I guess you do need more poles on the 5-way AND the four pole push/push. Are you SURE you can’t live with a coil split instead?!?
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Oct 15, 2020 18:26:10 GMT -5
Post by ashcatlt on Oct 15, 2020 18:26:10 GMT -5
No split, since I want to keep it noiseless with every pickup combination So but position 4 will (bridge (local parallel) parallel to middle) is three coils in parallel abs(1-1+1) = abs(1-1-1) = hum... Auto split in that position is easier than auto-parallel, though you still need more poles on the 5 way to make the other switch work only in position 5. That push-push still needs at least 3 poles or an active solution for the S/P + boost thing, so you might as well go for 4 and have all the cake you can want. I'm definitely not the one to talk to about mechanically hacking switches, and I'm not sure I can help much with finding an active solution, but they both seem like suitably Nutzy pursuits that hopefully somebody around here can advise on.
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Oct 16, 2020 11:23:49 GMT -5
Post by ashcatlt on Oct 16, 2020 11:23:49 GMT -5
Somebody please correct me if I’ve overlooked something, but the way I see it (“ya got to say sheeit, but don’t forget to drop me a line”) there are two wires that need to get switched. It’s the “series connection” wires - the top wire of the bottom coil and the bottom wire of the top coil. On the S/P switch, the other two are permanently connected to other things anyway. They each need to be the common on their own pole of the 5 way. The top wire from the bottom coil will jumper to hot output (whichever other pole of the switch is most convenient) at position 4, and to the S/P at 5. The bottom wire of the top coil likewise goes either to ground or to the S/P. There’s gonna be a whole lot of empty lugs on that switch, but that’s where we’re at. Edit - But hold up a second! We only ever want the boost off in position 5 when the S/P is in series mode, so that whole thing can just move to the S/P switch (once you finger out how to add a pole to that), so you actually only need 4 poles on your 5 way, so you can just use the switch you’ve got.
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Oct 17, 2020 2:40:18 GMT -5
Post by JohnH on Oct 17, 2020 2:40:18 GMT -5
I think there is a half chance that you could get something to work as you wish, using just the two-pole push switch.
Series / parallel switch can be done with one pole that either connects the two joined wires for series, or takes one of them to hot. The other pole only really needs to operate on the pickup in parallel mode, taking the upper coils lower connection to ground. So this second pole can be grounded, and in parallel mode it ground the pickup. In series mode it can provide a ground connection to something that will operate the boost.
So two ideas have legs:
it is possible that the two wires that control the boost, have one of those wires at ground, and by shunting the other to ground when connected, it shunts some signal in a voltage divider and so reduces gain. It could work that way. To check, you would test whether one of the two wires is actually a ground wire. if so, then you just use your second switch pole to apply teh ground in series mode to the other wire, thereby cutting the gain.
But, as Ash surmised, it is also possible and probably better, if this boost function is working by affecting the gain of an opamp stage. Given that its better, that's probably how it works.
There are two main generic ways to configure an opamp to provide a boost, with the level of boost controlled by switching components in th efeedbackloop. These are inverting and non-inverting arrangements. The non-inverting way could also control gain by shunting some negative feedback to ground, but this would tend to boost when the connection is made rather than cutting gain as here. So its probably the other, again as Ash said.
So, how to use a switch with a ground connection to increase feedback in an opamp loop? This would need a JFET, and if we are on a negative ground circuit think it will be a p-channel one. This can act like a switch. Take its gate to positive with a resistor and it will be off. Shunt it to negative and it will be on, increasing negative feedback an so reducing opamp gain.
That's all speculation but I reckon there is at least 50% chance that something there could work.
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Oct 18, 2020 3:41:40 GMT -5
via mobile
Post by JohnH on Oct 18, 2020 3:41:40 GMT -5
The jfet idea might work. It's by no means certain though. Depends if you're up for experimenting? If so, you'd rig it up first as a test before committing to it.
Things to find out first: What battery voltage does the circuit run at?
Is ground to battery negative or positive?
What voltages can be measured at the two connecting wires, when separate? and when connected?
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Oct 20, 2020 12:22:43 GMT -5
Post by ashcatlt on Oct 20, 2020 12:22:43 GMT -5
Maybe somebody can double check, but I'm pretty sure this does it with 4 poles on the 5 way. Wire the boost the same way you had in your last thing. It includes the resistor you wanted, only when the HB is on its own in parallel. (I had the black and yellow from the pickup backwards to begin with, caught it just before I posted, so from the 5way to the push-push looks wrong, but as long as the pickup to the 5way is right, it should work) EDIT - Ack! No. I think I steered you wrong a couple posts back. The way you have that boost wired now, it is completely dependent on the state of the push-push, so it doesn't turn offON when you switch away from the HB-only position. It actually will need two more poles on the 5 way to fix that. Might be nice to have the option of the boost in the other positions, but it's not automagical anymore.
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Oct 20, 2020 16:44:22 GMT -5
Post by ashcatlt on Oct 20, 2020 16:44:22 GMT -5
So yeah, this feature is supposed to only be disengaged by the P/P in pos 5, and active for everything else The way it is in your most recent diagram, it just does what it does depending on the P/P. It doesn't know or care what position the 5-way is in. It's my understanding that this is not what you actually want, so it needs to know and care what the 5-way is doing. I think it only needs one more pole though, actually. One of the wires needs to go to the (tactile on the side of the) P/P or not depending on the 5-way. The other can just go to that P/P switch. Yeah, you're right! Sorry about that. I thought I was being all sneaky, but...duh... I don't actually see how to make that happen without another pole on the P/P. Can you find that tactile switch in DPDT?
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Oct 28, 2020 9:28:16 GMT -5
Post by newey on Oct 28, 2020 9:28:16 GMT -5
Remind us where you are at with this, and what questions have yet to be answered. I thought that the issue was pretty much settled, you will need an extra tactile switch.
No need to move anything to a new thread.
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