OK, all these resistors and caps all over the place, it's a mess. And
still the same problems. The TL074 gets slightly warm to the touch.
The scaling at the outputs is about a semitone short over 4 octaves and
is influenced by the counter. I am assuming that others have
succesfully built asr's with this board? There are no revision numbers
on it but it's red and was purchased a few months ago.
I would like to verify that the input buffer is working correctly. I
read these voltages at the input to the ASR and the output of the
'input buffer' Could someone please verify these voltages? (much
appreciated)
Input voltage Voltage at TL074 pin 14
0V (C0) 6.64V
4V (C3) 4.83V
Also, what is the purpose of the 22k resistors to -15V on all buffer
inverting inputs?
still the same problems. The TL074 gets slightly warm to the touch.
The scaling at the outputs is about a semitone short over 4 octaves and
is influenced by the counter. I am assuming that others have
succesfully built asr's with this board? There are no revision numbers
on it but it's red and was purchased a few months ago.
I would like to verify that the input buffer is working correctly. I
read these voltages at the input to the ASR and the output of the
'input buffer' Could someone please verify these voltages? (much
appreciated)
Input voltage Voltage at TL074 pin 14
0V (C0) 6.64V
4V (C3) 4.83V
Also, what is the purpose of the 22k resistors to -15V on all buffer
inverting inputs?
> Cut the power rails to the TL074. Add 100 ohm in series between the
> power
> rails and the power pins. Add decoupling capacitors between the power
> pins
> and earth, and each other. Use 100n AND low ESR electros.
>
>> I've been staring at this asr for a few days now and I can't figure
>> out
>> its problem. I get very small (on the order of millivolts)
>> fluctuations in all outputs relative to the counter state. I replaced
>> the 10uF caps with 100uF. Power supply is ample and stable.
>> Resistors
>> are all hand precision matched. The other symptom is that the scale
>> factor is compressed- when driven by a keyboard the outputs are
>> slightly less than 1V/oct.