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Projects => General Questions => Topic started by: AntKnee on February 15, 2017, 02:42:52 PM

Title: Customizing pot values by adding resistors between solder lugs
Post by: AntKnee on February 15, 2017, 02:42:52 PM
I am working on a vero build that requires 150k pots. Using the Analog Alchemy page, I calculated what value resistors to put across the lugs of my pots. My vero build only requires soldering wires to lugs 2 and 3. Do I need to solder a resistor between lugs 1 and 2 AND lug 2 and 3, or can I get away with only soldering a resistor between the lugs I am using (2 and 3)?

(FYI, I am using 200k pots with 270k resistors to achieve 146k pot, according to the calculator, which is close enough for me.)
Title: Re: Customizing pot values by adding resistors between solder lugs
Post by: drolo on February 15, 2017, 03:24:10 PM
The maximum and minimum values of the pot will be correct, though you will modify the pot's taper. That might not be a problem though, depends on the circuit. You only need to solder the resistor to the 2 lugs you are using.
Title: Re: Customizing pot values by adding resistors between solder lugs
Post by: AntKnee on February 15, 2017, 04:29:08 PM
Quote from: drolo on February 15, 2017, 03:24:10 PM
The maximum and minimum values of the pot will be correct, though you will modify the pot's taper. That might not be a problem though, depends on the circuit. You only need to solder the resistor to the 2 lugs you are using.

I'm building a Keeley 4 knob compressor on vero. I don't know if the taper matters. Would I be better off just using 200k pots instead of 150K, in this case?
Title: Re: Customizing pot values by adding resistors between solder lugs
Post by: drolo on February 15, 2017, 04:47:56 PM
I'm afraid I have never seen that schematic, would you have a link to the one you are working with?
Title: Re: Customizing pot values by adding resistors between solder lugs
Post by: AntKnee on February 15, 2017, 05:13:10 PM
Quote from: drolo on February 15, 2017, 04:47:56 PM
I'm afraid I have never seen that schematic, would you have a link to the one you are working with?

I don't know which one they used for the Tagboard layout, but here is one that I hope helps.

(http://i650.photobucket.com/albums/uu229/MNhutDevil/Keeley_C4_Compressor_schem.jpg~original)
Title: Re: Customizing pot values by adding resistors between solder lugs
Post by: sonnyboy27 on February 15, 2017, 05:22:12 PM
Based on the tagboard layout (because I'm looking at doing the same thing) I'd say you only need it across the lugs 2 and 3 for the clipping pot, and lugs 2 and 3 of the attack pot.
Title: Re: Customizing pot values by adding resistors between solder lugs
Post by: drolo on February 15, 2017, 05:28:30 PM
It's probably not going to be a big deal having 200k.
Give it a try and if you hear any weird stuff happening (I doubt it ) when the pots are maxed out at 200k add the resistor to bring the max resistance down.



Title: Re: Customizing pot values by adding resistors between solder lugs
Post by: dbp512 on February 15, 2017, 09:33:40 PM
I built this on stripboard a year ago, I don't remember for sure but I think I used a 100k pot and it was fine. I didn't notice anything weird and I didn't feel like it was missing any of its range. I never played an original to compare, so take what I say with a grain of salt. Luckily part of the fun of diy is that you get to experiment.
Title: Re: Customizing pot values by adding resistors between solder lugs
Post by: devilsnight on February 16, 2017, 06:36:18 AM
In this case you could try the 200k pots and then prop the resistor on there and try it that way too, see if there is a difference. Assuming you have solder lug pots that wouldn't be too difficult.