[sdiy] Critique my gate output buffer?

[Jonatan Liljedahl]

I think one problem with such hidden wire-ORable outputs is that it’s
difficult to remember which modules has it or not. In the heat of making
the best patch ever, you don’t want to change focus trying to remember it
or looking it up.

/Jonatan
http://kymatica.com


tis 26 nov. 2024 kl. 20:42 skrev Paul Glass-Steel via Synth-diy <
synth-diy at synth-diy.org>:

> Chris,
>
> Thanks for your thoughts on this. After another round of experimentation
> I'm once again leaning towards a transistor-based solution; I wasn't really
> able to come up with a realistic use case where the op-amp seemed much
> better. I'm also thinking about your question of the wire-OR function
> really being worthwhile. I have a fine dedicated OR module and sometimes,
> it's nice to not have what seems like "hidden" functionality.
>
> -Paul
>
> On Mon, Nov 25, 2024 at 11:42 AM Chris McDowell <declareupdate at gmail.com>
> wrote:
>
>> K one more.
>>
>> What happens here is the more outputs you OR together in this way, the
>> lower that 22k looks and the more voltage develops across your 1k resistor,
>> which basically wont ever really matter. I still think tempting your op amp
>> to overshoot or whatever funky thing it wants to do with your diode and
>> cable capacitance is unnecessary given that a 220R resistor in series with
>> the diode would handle it. or put the parallel R and C from output to minus
>> input like you know you're supposed to :P
>>
>> in my personal system, everything has some manner of 100k to ground on
>> the inputs and I would leave the 22k out entirely. I guess what I would
>> *actually* do is build an explicit OR module.
>>
>> Cheers,
>> Chris
>>
>> On Nov 25, 2024, at 11:20 AM, Chris McDowell <declareupdate at gmail.com>
>> wrote:
>>
>> This is like swapping your output resistor with a diode, which means
>> your capacitive load is only, yknow, capacitively loading when the diode is
>> conducting. I don't think there is a lot of value in putting the output
>> resistor in the feedback loop for gate outputs, as we'd usually do that to
>> increase DC accuracy at the receiving equipment. I would move your output
>> resistor out of the feedback loop to take stability out of the
>> conversation. You then have something pretty normal that will OR with
>> similar outputs, up to some limit where all your 100ks (and whatever all
>> the various input resistances) in parallel are too low a resistance to get
>> your gates across. that's a lot, though.
>>
>> Cheers,
>> Chris
>>
>> On Nov 24, 2024, at 12:42 PM, Paul Glass-Steel via Synth-diy <
>> synth-diy at synth-diy.org> wrote:
>>
>> 
>> I'm hoping to improve on the typical transistor emitter-follower, wire-OR
>> capable gate output buffer that many of my modules have inherited from CGS
>> and NLC. I've come up with this: https://tinyurl.com/259pt83t - it seems
>> happy on my bench, the voltage is stable under a lot of fan-out to multiple
>> inputs and it seems ok with long cables / capacitive loads. But I thought
>> I'd check here to see if I'm missing something.
>>
>> Thanks,
>> -Paul
>>
>>
>> ________________________________________________________
>> This is the Synth-diy mailing list
>> Submit email to: Synth-diy at synth-diy.org
>> View archive at: https://synth-diy.org/pipermail/synth-diy/
>> Check your settings at: https://synth-diy.org/mailman/listinfo/synth-diy
>> Selling or trading? Use marketplace at synth-diy.org
>>
>> ________________________________________________________
> This is the Synth-diy mailing list
> Submit email to: Synth-diy at synth-diy.org
> View archive at: https://synth-diy.org/pipermail/synth-diy/
> Check your settings at: https://synth-diy.org/mailman/listinfo/synth-diy
> Selling or trading? Use marketplace at synth-diy.org
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20241126/d2f69b1f/attachment.htm>