[sdiy] emulating bi-polar capacitors

Oren Leavitt obl64 at ix.netcom.com
Tue Feb 15 21:40:53 CET 2022


On 2/15/22 1:42 PM, Barry Klein via Synth-diy wrote:
> I used one in a typical dual op amp triangle oscillator on the phaser in a Music Man amp design. It made a difference in extremely slow sweep symmetry and also I had a function where you pull the knob out and could fix the sweep wherever you wanted it. After I left the whole thing was redesigned. Maybe I didn’t know what I was doing….  45 years ago… Self-taught by Electronotes. What a fun job before work politics F’d it all up.
>
> Barry
>
I'll concur. I think that's the only genuine use case I've found for a 
bipolar electrolytic cap - as the timing cap in a basic tri/square LFO, 
and also in slew limiting circuits that can go negative or positive. For 
audio coupling and most other cases, a plain ol' electrolytic worked fine.

- Oren

>> On Feb 15, 2022, at 11:32 AM, Mike Bryant <mbryant at futurehorizons.com> wrote:
>>
>> 
>>> I've never bothered, I've never noticed a difference in just using a 47μ instead of playing about with back-to-back capacitors even after the thick end of 40 years the earliest stuff I built that way still has capacitors that capacitate just fine.
>> --
>>> Gordonjcp
>>
>> Agreed.  Unless you actually have a reverse DC bias voltage (in which case rotate the capacitor) I've never understood any need for the non-polarised capacitors.  Most mixing consoles are full of thousands of them either feeding the input or fed from the output of an opamp via a resistor to ground.
>>
>>
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