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Post by newey on Jan 20, 2011 21:54:16 GMT -5
In case anyone runs across an old Teisco E 200 or ET 200 (these are the 2-pickup "tulip" guitars), here is a wiring diagram, as posted by mcphoto on the VintAxe forums:  This is an interesting scheme, especially for a sixties-era guitar. It is a sort-of modified binary tree set-up, giving either bridge or neck alone, both in series, or both shorted (i.e., "off").
Update on 2021-02-02 by Yogi B: VintAxe link updated. The image is viewable there, or within a capture of mcphoto's blog via the WaybackMachine. |
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Post by wolf on Jan 21, 2011 16:46:10 GMT -5
NeweyI went to that forum and posted the true binary tree circuit:  That Teisco circuit is interesting but isn't it better to have the fourth tone option as parallel switching instead of "off"?
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Post by asmith on Jan 21, 2011 20:33:44 GMT -5
Wolf,
I agree with your sentiment about the parallel option, but in your diagram, with the switches set at (from left to right) Up Down, the Bridge hangs from hot.
Some care, some don't.
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Post by wolf on Jan 21, 2011 22:50:41 GMT -5
asmithYes, I will admit it does that. Still, I have wired a lot of guitars like that and (to me) it doesn't make a difference. In fact, the Seymour Duncan Triple Shot™ pickup ring (and they may have "found" that idea from this or my website) works exactly the same way. Two SPDT switches are wired just like that - and they charge 30 bucks for it. 
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Post by ashcatlt on Jan 24, 2011 10:44:15 GMT -5
Well, both bridge wires are connected to the "hot" output in that case. That is not what I call hanging from hot. It's just off.
BTW - this seems to be pretty standard for this "class of instruments". My ugly little shortscale bass is the same.
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Post by asmith on Jan 24, 2011 15:16:57 GMT -5
Ash, Green is the Bridge signal, Blue is the Neck signal.  |
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Post by wolf on Jan 24, 2011 16:00:05 GMT -5
Replying to the previous posting:  In Diagram 1, coil A is "on" but coil B has its negative terminal unconnected, so coil B is "hanging from the hot". |
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Post by ashcatlt on Jan 24, 2011 17:18:15 GMT -5
Yeah, sorry. I'm not going to make excuses, I just failed in my analysis.
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Post by JohnH on Jan 24, 2011 17:18:51 GMT -5
I would think that if two-pole switches are used, it should be possible to avoid hanging from hot. Such switches are neither significantly larger nor much more expensive than single pole, so there's no reason not to use them. Im convinced that hanging from hot should always be avoided if possible, unless all wiring is within a shielded cavity and all pickups are covered. Its not a really big deal, but it can slightly reduce unwanted buzzes', so it may as well be avoided. I also think that hanging from hot applies not only to a single connection to hot, but also if both connections end up on hot. I have some wirings where this is happening, and they work fine, but I believe there is a very slight extra buzz sometimes.
John
J
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Post by asmith on Jan 24, 2011 21:20:15 GMT -5
Ash,
I feel like a bit of a dick. My apologies.
John,
I knew it! Agh, more switch work for me.
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Post by JohnH on Jan 24, 2011 21:55:15 GMT -5
I knew it! Agh, more switch work for me. Its an easy fix, the job of the other two poles is to break the connection from bridge to hot, only when bridge is off and neck is on. Two switch poles in parallel will do that, so only if both are open is the bridge hot connection broken. J |
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Post by wolf on Jan 24, 2011 22:21:42 GMT -5
Well, here is the proper way to do this with 2 DPDT switches:  (Please recheck that diagram. Thanks.) Remember that in the Seymour Duncan Triple Shot™ pickup ring, even though they use 2 DPDT switches, they are wired as if they are just SPDT switches and therefore, everybody using these should be getting "hanging from the hot" problems. Here's the thread from that Triple Shot™ discussion. |
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Post by ashcatlt on Jan 25, 2011 2:17:17 GMT -5
Ash, I feel like a bit of a dick. My apologies. Don't! I was wrong. It does happen sometimes*. I think the diagrams proving that I was wrong will help other folks better understand what's going on. It works out. * Don't tell my wife I admitted it, though! I'll deny everything.  |
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Post by JohnH on Jan 25, 2011 6:43:37 GMT -5
looks fine wolf. Here is a very slight variation:  not better, but one or two less connections J |
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Post by asmith on Jan 25, 2011 8:58:48 GMT -5
John, I meant with all the other diagrams I've drafted up, stored on my hard drive - some of them work in places by shorting a pickup at hot. Perfectionism is a dirty job. Edit: Example. Wolf, Interesting that SD uses DPDTs but wires them like SPDTs. I would have thought a company like that would have more 'electrical sense.' I'd be very disappointed if it turned out they don't wire this up because they think a single-coil should have hum - but I can't say I'd be surprised. Ash, Threaten to tell your wife?! I would never stoop so low to that; the very worst type of blackmail.
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Post by wolf on Jan 25, 2011 23:46:39 GMT -5
JohnH
I like your re-design of that circuit - and a +1 to you.
asmith
Yes, it is surprising that Seymour Duncan wired the switches that way, especially when they announced a production delay because they were waiting for DPDT switches.
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