Jext Telez - White Pedal  [traced]

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Re: Jext Telez - White Pedal

Postby Frank_NH » 04 Feb 2018, 04:35

Here's quickie demo for the Yer Blues Fuzz on Vimeo. Notice all the wires around my breadboard (yikes!). :D :shock: :lol:

https://vimeo.com/254156214

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Re: Jext Telez - White Pedal

Postby Motter » 04 Feb 2018, 09:34

Great job, and nice tones Frank! You're right, the MRB and cocked wah sounds really make this circuit what it is. Can your circuit run at 9V? I'm not enthusiastic about charge-pumping everything out there the way some builders seem to be.
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Re: Jext Telez - White Pedal

Postby albru80 » 04 Feb 2018, 14:42

Great job, Frank!
I've drawn a layout that should fit in a 125B box:
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Re: Jext Telez - White Pedal

Postby Frank_NH » 04 Feb 2018, 21:03

Motter wrote:Great job, and nice tones Frank! You're right, the MRB and cocked wah sounds really make this circuit what it is. Can your circuit run at 9V? I'm not enthusiastic about charge-pumping everything out there the way some builders seem to be.


OK - here's a stripped-down 9V version! :D

After some LTSpice redesign and a go on the breadboard, it turns out that the gain stages can run comfortably at 9V, but in addition you can simplify the clipping and just make it straight to ground (unlike my 18V version, where I tried to stay truer to the original preamp voltages). I've shown this with some 1N34A clipping diodes but you can retain the original two PNP transistor clipping and experiment with germanium transistors. I think, overall, it retains the spirit of the Conqueror preamp. By the way, the original preamp had a second transistor gain/mixer stage after the tone stack and before going to the power amp, so that could be added if you wanted more output (this gets enough output for a pedal).

Have fun!
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Re: Jext Telez - White Pedal

Postby Frank_NH » 04 Feb 2018, 21:13

albru80 wrote:Great job, Frank!
I've drawn a layout that should fit in a 125B box:


Thanks Alex! Check out the 9V version. :D
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Re: Jext Telez - White Pedal

Postby albru80 » 05 Feb 2018, 15:38

Cool! This is the 9V version (with clipping transistors):
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Re: Jext Telez - White Pedal

Postby Frank_NH » 05 Feb 2018, 16:01

albru80 wrote:Cool! This is the 9V version (with clipping transistors):


Thanks again! I'll see if I can get this one built this week. You definitely want to socket the clipping transistors and try out your favorite PNPs. Silicon PNPs will work but perhaps not have the mojo of germanium. I unfortunately don't have very many germanium transistors in my parts stash so I'll to order some from Small Bear.
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Re: Jext Telez - White Pedal

Postby Motter » 05 Feb 2018, 16:04

Frank, I've got dozens of germanium transistors and diodes, and I'll never use all of them. Send me your mailing address
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Re: Jext Telez - White Pedal

Postby Frank_NH » 05 Feb 2018, 16:38

Motter wrote:Frank, I've got dozens of germanium transistors and diodes, and I'll never use all of them. Send me your mailing address


Thanks for the offer. Let me get this built first and I'll let you know. The original used the ACY22 PNP germanium transistors, with an hfe minimum of 30. Not sure what the equivalent would be but one could try any of the usual suspects (e.g. AC128...). Also not sure what the effective forward voltage is when wired as a diode, but that would be useful information.

https://www.digchip.com/datasheets/part ... 22-pdf.php
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Re: Jext Telez - White Pedal

Postby natron_mn » 11 Jun 2018, 17:04

Looking to build this, using the layout by Effects Layouts. I'm a newb with inductors. I've got the Dunlop 500mh inductor for this build. Does orientation matter with inductors? Or can I place the 4 pins any which way?

Image
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Re: Jext Telez - White Pedal

Postby Motter » 17 Jun 2018, 22:34

Well there's two coils in there, so each pair of pins is a separate coil. Measure the dc resistance to find which pairs are connected, and then put them in parallel across the two rails on the PCB.


Edit: oops, the wah inductor should only have one coil. That means you'll only get a measurable DC resistance across two of them. Make sure you have these wired across the rails, the other two are just for mounting and have no electrical connection.
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Re: Jext Telez - White Pedal

Postby natron_mn » 21 Jun 2018, 21:57

Motter wrote:Well there's two coils in there, so each pair of pins is a separate coil. Measure the dc resistance to find which pairs are connected, and then put them in parallel across the two rails on the PCB.


Edit: oops, the wah inductor should only have one coil. That means you'll only get a measurable DC resistance across two of them. Make sure you have these wired across the rails, the other two are just for mounting and have no electrical connection.


Thanks! So if I get a measurable resistance across two leads, then on of those leads will go in the slot connected to the 220ohm resistor and 100nF cap, and the other lead will go in the slot connected to the Yoko 5 switch, 10k resistor and 10nF cap? Sorry to be so dense about this, but again - new to inductors!
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Re: Jext Telez - White Pedal

Postby Motter » 22 Jun 2018, 16:14

That is my understanding, yes. The DC resistance may be quite low, so put your multimeter on it's lowest range. The actual measurement doesn't matter, we're just trying to find out which two pins are connected to the coil.
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