Author Topic: Tractor Beam update  (Read 2379 times)

jimilee

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Re: Tractor Beam update
« Reply #15 on: October 10, 2017, 07:40:25 PM »
That's a sexy phaser
Pedal building is like the opposite of sex.  All the fun stuff happens before you get in the box.

Jules

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Re: Tractor Beam update
« Reply #16 on: October 10, 2017, 10:12:41 PM »
Great! Thanks a lot.

Netnnk

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Re: Tractor Beam update
« Reply #17 on: October 26, 2017, 04:16:00 PM »
Is this how to assemble your own resistor arrays for the Tractor Beam?

*edit* Updated. Thanks, WormBoy!

« Last Edit: October 27, 2017, 03:38:17 AM by Netnnk »

WormBoy

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Re: Tractor Beam update
« Reply #18 on: October 27, 2017, 01:13:13 AM »
Isolated looks good. For bussed, the bus needs to be directly connected to pin 1, so basically you would replace one of the outer most resistors with a jumper. As Brian explained in another thread: it does not matter whether thatís the first or the last (quirk of the tractor beam design: both the first and the last pin of the bussed array are connected to ground, so one resistor is in fact unused). I would always quickly check the board with a DMM, just to make double sure  ;D.

greenskull

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Re: Tractor Beam update
« Reply #19 on: November 06, 2017, 08:41:26 PM »
Many thanks, I just received my boards today!
I didn't notice the Tractor Beam listed on the switching board doc..... what voltage zener do I need?
Also want to double check I need the charge pump chip. Thank you very much.

WormBoy

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Re: Tractor Beam update
« Reply #20 on: November 07, 2017, 01:59:47 AM »
The Tractor Beam is on the last page of the switching board doc, in the schematic. States a 16v zener, but if you only run it on 9v, you can easily use something lower (it is only there to protect against overvoltage). The charge pump is in the photo in the TB build doc, and if you look at the opamp voltages, it is indeed used  8).

greenskull

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Re: Tractor Beam update
« Reply #21 on: November 07, 2017, 01:50:52 PM »
Thanks, Wormboy! I might need glasses.

mark123

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Re: Tractor Beam update
« Reply #22 on: November 11, 2017, 07:22:26 AM »
When I'm matching the JFETs, what is the tolerance? How close do they have to be?

287m

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Re: Tractor Beam update
« Reply #23 on: November 11, 2017, 08:20:49 AM »
When I'm matching the JFETs, what is the tolerance? How close do they have to be?
as close as possible
while we waiting Brian project jfet matcher, you can view NomNom docs

mark123

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Re: Tractor Beam update
« Reply #24 on: November 11, 2017, 10:34:14 AM »
... you can view NomNom docs
I saw that mentioned but didn't know what it meant. I Binged it and figured it. Thanks.

From the Nomnom doc:
Quote
You want to find the closest matching voltage readings on these transistors. At least within 5% of one another, although I generally shoot for 1% or less. So, if a device reads ≠0.75vDC, I would look for another one that measures ≠0.74 to ≠0.76v.
Exactly what I was looking for.  Since we're looking at Vgs I'm just thinking of picking up a semiconductor analyzer.

mark123

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Re: Tractor Beam update
« Reply #25 on: November 18, 2017, 12:29:26 PM »
The Tractor Beam uses the TC7662B and the low ESR Electrolytics, correct?  It's not listed in the switching board "Used With" column but it is in the picture of the doc.
« Last Edit: November 18, 2017, 12:57:43 PM by mark123 »

madbean

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Re: Tractor Beam update
« Reply #26 on: November 18, 2017, 02:22:14 PM »
Correct.
I own madbeanpedals (duh). I am part owner of Function F(X).

mark123

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Re: Tractor Beam update
« Reply #27 on: November 27, 2017, 05:12:22 PM »
*disregard*
« Last Edit: November 27, 2017, 07:35:07 PM by mark123 »