[sdiy] Vactrol vs H11F1M optoFET

[Mike Bryant]

Ah ok thanks.  Wouldn't be possible for what I want to do.  Thanks.

________________________________
From: Jacob Watters <jacobwatters at gmail.com>
Sent: 24 October 2025 01:41
To: Brother Theo <brothertheo2014 at gmail.com>
Cc: Mike Bryant <mbryant at futurehorizons.com>; SDIY <synth-diy at synth-diy.org>
Subject: Re: [sdiy] Vactrol vs H11F1M optoFET

This guy made a filter with them a long time ago and mentioned this email list:

https://youtu.be/Zpf4WLRaU0M?si=HTsYbVnvP4UHYdom

Also, I think that RYO made a low pass gate with it, but one of the designers said that you have to lower the input volume a lot to reduce clipping.

I have some, but never got around to testing them yet.


Jacob Watters
JacobWatters.com<http://jacobwatters.com/>

On Thu, Oct 23, 2025, 8:24 p.m. Brother Theo via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>> wrote:
you need 2 right? one for output and one for feedback?

--TimR

On Thu, Oct 23, 2025 at 6:40 PM Mike Bryant <mbryant at futurehorizons.com<mailto:mbryant at futurehorizons.com>> wrote:
On a related note, has anybody experience using these :

https://www.digikey.co.uk/en/products/detail/onsemi/H11F1M/1793945

Upsides and downsides ?
________________________________
From: Synth-diy <synth-diy-bounces at synth-diy.org<mailto:synth-diy-bounces at synth-diy.org>> on behalf of crystal via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>>
Sent: 23 October 2025 22:31
To: mark verbos <markverbos at gmail.com<mailto:markverbos at gmail.com>>
Cc: synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org> <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>>
Subject: Re: [sdiy] opto isolator "Vactrol" tester


They're not labeled, but, i think they are that same part. I had some very mixed results , but, since i bought a large bag of them, i just threw the really slow parts in their own envelope. Since they were for my own circuits i liked the (occasional) lower on resistance.

Hadn't though to shine a light on them externally. Next time...

Crystal

On 10/20/2025 5:06 AM, mark verbos wrote:
I have had VERY unreliable experience with the Silonex parts. I used NSL-32SR3 which are meant to be the fast ones but I had places where they would take several seconds to decay. Oddly, it made a difference if I had them in an inline resistor verses as one part of a voltage divider. Also, not necessarily a bad thing, but their on resistance is much lower than in the Vactec/PerkinElmer/Excilitas ones.

Mark




On Oct 19, 2025, at 10:58, crystal via Synth-diy <synth-diy at synth-diy.org><mailto:synth-diy at synth-diy.org> wrote:


Can someone point to a testing circuit for "Vactrols?"

I bought a bag full of Siliconex optos years ago, they are all over the map in response time.

I had tested quite a few in a very crude breadboard setup, mostly just looking at on/off resistance timing and off resistance and then putting them in envelopes with details written on them. I'm sure i could do that again, i'm just wondering if it's been done better.


thanks,

 Crystal

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