Thanks Os. I remember reading something about it on this forum. Can't remember where, exactly.
It that diode implemented on the latest PCB version? I can't find it in the build guide, nor in the schematic and in the BOM. What does it connect to and in what direction? Which type should it be?
It that diode implemented on the latest PCB version? I can't find it in the build guide, nor in the schematic and in the BOM. What does it connect to and in what direction? Which type should it be?
low reverse leakage type , anode to Q10 collector.
Have some fun , start at the "bav's" , look for low nano amp to pico amp reverse
leakage specs. higher voltage reverse voltage ratings (200V+).
OS
Something like a BAV21? Ir ca 100nA at 200V.
Why is that "having fun"?
[EDIT]
1N485B has Ir=25nA at 175V. Is that one better suited?
See , you answered your own question .... Fun !
As a guideline , for safety - the diode has to be de-rated >20% reverse breakdown
greater than the highest expected VAS waveform .... (which is rail total minus about
3 volts).
100nA takes THD down @ 3ppm , I have one model that is <50nA - about the same - with or without it.
If your rails are on the higher side and you never intend to "hard" clip this amp,
the diode can be omitted (another option). But , with low enough reverse
leakage , amplifier performance will be unaffected.
OS
JamesBlond, OS explained the BC clamp better than I could have. I just have not yet soldered it in, from OS' answer, I have no idea. OS will hopefully answer. He's been great about that.
Gozmosis, That is exactly what I did, on purpose. I ordered all 1/2W resistors instead of 1/4 watt, they fit all the holes just fine. No problems. your english is great!
OS, I answered all my own questions I had earlier asked. The answers were self-evident as I populated the boards. I was just looking at the schematics and not thinking , just looking.
Gozmosis, That is exactly what I did, on purpose. I ordered all 1/2W resistors instead of 1/4 watt, they fit all the holes just fine. No problems. your english is great!
OS, I answered all my own questions I had earlier asked. The answers were self-evident as I populated the boards. I was just looking at the schematics and not thinking , just looking.
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If in the presence of higher voltage, carbon may be preferable at base stopper locales.
However, the quality of the resistor will probably matter more than the materials used in its construction. So avoid the chinese bargain resistors with the almost hair thin leads. Xicon will do fine. Koa might do better.
In the diyAB build guide PDF written by JojoD818 under the Bias Calculations heading it reads;
"Bias calculations:
For 100mA bias per pair, measure about 44mV between TP1 and TP2.
I = 44mV (measured between TP1 and TP2) / 0.44
I = 0.1A = 100mA"
Shouldn't the next to last line read,
I = 44mV (measured between TP1 and TP2) / .044 ?
I think the decimal is in the wrong place. or am I missing something?
Ron
"Bias calculations:
For 100mA bias per pair, measure about 44mV between TP1 and TP2.
I = 44mV (measured between TP1 and TP2) / 0.44
I = 0.1A = 100mA"
Shouldn't the next to last line read,
I = 44mV (measured between TP1 and TP2) / .044 ?
I think the decimal is in the wrong place. or am I missing something?
Ron
