[sdiy] Vactrol vs H11F1M optoFET

[Jacob Watters]

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> 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>
> 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> on behalf of crystal
>> via Synth-diy <synth-diy at synth-diy.org>
>> *Sent:* 23 October 2025 22:31
>> *To:* mark verbos <markverbos at gmail.com>
>> *Cc:* synth-diy at synth-diy.org <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> <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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