Author Topic: 250K Trimmer Source?  (Read 403 times)

steveyraff

250K Trimmer Source?
« on: March 07, 2018, 09:38:49 AM »
Hey guys,

Can anyone help me source a 6mm 250k trimmer. Its for a Phase 90 I'm building. I am talking about something like this: https://www.bitsbox.co.uk/index.php?main_page=product_info&products_id=2309

I ordered 2 online that looked correct in the photos, but hadn't any dimensions in the description. They're way too big to fit on the board. I need the correct spacing, as with the 6mm version linked.

PS. I am in Ireland/UK.

Thanks!
Steve.

vigilante397

Re: 250K Trimmer Source?
« Reply #1 on: March 07, 2018, 09:59:48 AM »
It may take a while to get there, but Tayda has you covered 8)

https://www.taydaelectronics.com/250k-ohm-trimpot-variable-resistor-6mm.html
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steveyraff

Re: 250K Trimmer Source?
« Reply #2 on: March 07, 2018, 12:57:02 PM »
Thanks. Hmm, was hoping to have it for a gig this weekend. The 250k trimmer I do have now is about the size of a penny, maybe a bit smaller. I might try just wiring it in somehow, and seeing if I can make it fit lol.

YellowBoy

Re: 250K Trimmer Source?
« Reply #3 on: March 07, 2018, 01:11:30 PM »
Yes Raff!

The trimmer is set and forget so just wire in a standard pot, adjust till desired phasiness, then remove the pot and measure the resistance between lug 1 and 2.....then measure between lug 2 and 3.  Then simply find two resistors that closely match your measurements and solder them in place of the trimmer....so one end of both resistors will connect to the same place the middle lug on the trimmer would go.

I only use trimmers for prototyping these days.  Putting one on a board just seems a waste of money/components

Ciaran

vigilante397

Re: 250K Trimmer Source?
« Reply #4 on: March 07, 2018, 02:41:10 PM »
The trimmer is set and forget so just wire in a standard pot, adjust till desired phasiness, then remove the pot and measure the resistance between lug 1 and 2.....then measure between lug 2 and 3.  Then simply find two resistors that closely match your measurements and solder them in place of the trimmer....so one end of both resistors will connect to the same place the middle lug on the trimmer would go.

If you need it for this weekend that's definitely the way to go.
"I'm not sure what "serious design flaws" you see. Does it explode or poison your dog?" - PRR

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http://www.sushiboxfx.com

digi2t

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Re: 250K Trimmer Source?
« Reply #5 on: March 07, 2018, 08:26:08 PM »
Do a search for Piher trimmers. They make a 6mm model. I believe they're widely available in the EU.

https://www.mouser.com/ds/2/325/11-PT6v03-4455.pdf
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PMowdes

Re: 250K Trimmer Source?
« Reply #6 on: March 08, 2018, 03:00:48 AM »
Try Thonk.co.uk

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PMowdes

Re: 250K Trimmer Source?
« Reply #7 on: March 08, 2018, 03:03:57 AM »
Try Thonk.co.uk

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Or Tayda

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PMowdes

Re: 250K Trimmer Source?
« Reply #8 on: March 08, 2018, 03:16:10 AM »
You could also try a 200k or 500k trimmer in there (from bitsbox), the trimmer in a phase 90 sets the point at which the phasing starts to work, depending on your transistors its usually near the middle of the sweep so I think you'll be OK, I've used a 200k before.  The second trimmer if you have one sets the amount of feedback through the script switch mod

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PMowdes

Re: 250K Trimmer Source?
« Reply #9 on: March 08, 2018, 03:18:10 AM »
Here's an interesting article and circuit analysis https://www.electrosmash.com/mxr-phase90

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steveyraff

Re: 250K Trimmer Source?
« Reply #10 on: March 08, 2018, 08:16:09 AM »
Thanks guys, all very helpful. I think I should be ok now. Cheers all!