[sdiy] Elektor Formant Re: Test / Sequencer / Arduino

[Harald]

Hello Nantonos,

yes the "circular transparent chamber" is to prevent airflow-induced 
temp changes. And it makes for faster warm up and less thermal stress 
for the uA726.

When you have the VCO on the bench and waves a sheet of paper to 
simulate some airflow you can here the pitch change. In a closed cabinet 
you can have some circulation as well if it is big enough or ventilated.

I just cut the top of a plastic syringe and put it over the metal can.

I agree. All CV concerning pitch and other important voltages should be 
derived from precision sources.

Harald

www.haraldswerk.de


Am 26.03.2015 um 15:32 schrieb Nantonos:
> Hello Harald,
>
> Thursday, March 26, 2015, 10:24:38 AM, you wrote:
>
>> for your resting uA726 this might be of interest:
>> http://www.haraldswerk.de/NGF/NGF_VCO_CORE_ONE/VCO_CORE_ONE.html
>> I have rebuild the Formant VCO with some modern parts keeping the
>> overall architecture original.
>
> I wish more circuits did what you have done, deriving important
> voltages from precision voltage references (REF02Z and REF102AP in
> your case).
>
> Its depressingly common even today to see voltages derived from
> resistive dividers across the power rails. Op-amps with PSRR of 80dB
> being used with voltage sources whose PSRR is less than 10dB.
>
> The circular transparent chamber is to prevent airflow-induced
> temperature changes?
>