Transistor FET 2N3820 equivalent

HeavyMetalfx · August 16, 2023, 06:50:53 AM

Does anyone know of a readily known equivalent for a Transistor FET 2N3820?

GibsonGM · August 16, 2023, 07:29:33 AM

If you post a schematic of what you're hoping to use the sub in, that would make it easier to find a suitable replacement. I have seen this discussion on other boards, and it seems they usually trim out the replacement to get it to act properly...new FETs are much better, basically.

HeavyMetalfx · August 16, 2023, 07:57:21 AM

Clint Eastwood · August 16, 2023, 07:59:06 AM

2N5460, 2N5461 or 2N5462 are all equivalent to 2N3820, but with different pinout. And with the 2N546x range they made three different groups according to Idss value.
They are all obsolete, and being P-channel jfets, there are very few of those in production today, at least as through-hole device.
There still is the j17x series made by Onsemi, maybe the j176 would work in your circuit.

antonis · August 16, 2023, 08:00:16 AM

Quote from: HeavyMetalfx on August 16, 2023, 07:57:21 AM

I can har5dly see some op-amps (guess)..

HeavyMetalfx · August 17, 2023, 04:17:13 AM

HeavyMetalfx · August 17, 2023, 04:18:30 AM

Sorry, it's a terrible picture.

Rob Strand · August 17, 2023, 05:17:38 AM

Quote from: HeavyMetalfx on August 16, 2023, 06:50:53 AM
Does anyone know of a readily known equivalent for a Transistor FET 2N3820?

Oh, the Fairchild datasheet is fairly open ended
https://pdf1.alldatasheet.com/datasheet-pdf/view/83029/FAIRCHILD/2N3820.html

Silconix suggest J270 as an equivalent:

Low-ish Vgs_off P-channel. Idss fairly normal to high.

Good chance you will want an equivalent to that

I can read the schematic at all. Can't even tell if it's a P-channel

.

Chillums · August 17, 2023, 05:43:52 AM

Just throw up a link to the build doc your working from.

HeavyMetalfx · August 17, 2023, 06:24:28 PM

Sorry guys, really crappy pics. Here is the link to the build doc.

https://pcbguitarmania.com/wp-content/uploads/2022/05/Solid-Metal-Pro-Building-Docs-28th-December-2022.pdf

PRR · August 18, 2023, 12:48:15 AM

Keep clicking, this should open 19" 50cm wide.

PRR · August 18, 2023, 12:52:22 AM

These are switches. Switching gain/response in amplifier stages. The only critical spec is P-type JFET. Should be simple. But JFETs are dying, and P-types died first.

N-types would need a negative supply AND a lot of re-rigging.

You could replace with 4066 CMOS but keeping the polarities straight is too much for my mind.

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Transistor FET 2N3820 equivalent