no porn, no glory
though, I can't tell anything about blue led's TempCo, vs. Green ones
you will tell how stable effective biasing (in time domain) is ....... just take a look how much slide of lower puck drain voltage you have ....... and then only test blue vs. green can tell which ones are effectively better
though, I can't tell anything about blue led's TempCo, vs. Green ones
you will tell how stable effective biasing (in time domain) is ....... just take a look how much slide of lower puck drain voltage you have ....... and then only test blue vs. green can tell which ones are effectively better
Latest update. Worked flawlessly in bringing up bias ma by ma. Came up a bit short though. Current was 3 amps instead of 3.2 and Vds was 35 volts instead of 30. The two blues may have been a touch too much. Looking for some greens in the basement tomorrow.
Regards,
Dan 🙂
Regards,
Dan 🙂
not open enough, so it seems your pucks are asking for more of Ugs than you're having
it seems two blue ones aren't enough
add one 1N4148 in series with blue ones, same orientation - cathode down to GND
it seems two blue ones aren't enough
add one 1N4148 in series with blue ones, same orientation - cathode down to GND
Added a 1N4007 I had handy. Results are better. I now have full range of adjustment. Waiting to see if things heat up and we'll go from there.
Right now CCS Vds 27.4 Vgs 3.60
Lower Vds 29.6 Vgs 4.21
Total current 3.058A
The two primary components in my ZM inspired bias circuit are.
Blocked
https://www.mouser.ca/ProductDetail/Cree-Inc/C503B-BAN-CX0B0462?qs=%2Fha2pyFaduidizlAeORLOCSXK2DsFxnOyiDNVqWljItuKlk1a2lg2JM%2FXfapAfuE
Regards,
Dan
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like what I see
though, one thing still mysterious - with (now) lower Ugs of 4V21, how you didn't had that with just two blue leds?
and one more thing - when you read "1N4148", in some cases you can replace it with 1N400x, in some cases not
in this case, 400x will not give neither same voltage drop nor will have same TempCo as 1N4148
400x is Brute, comparing to 4148
though, one thing still mysterious - with (now) lower Ugs of 4V21, how you didn't had that with just two blue leds?
and one more thing - when you read "1N4148", in some cases you can replace it with 1N400x, in some cases not
in this case, 400x will not give neither same voltage drop nor will have same TempCo as 1N4148
400x is Brute, comparing to 4148
In this case I had to use whatever was in my spare parts bin and hope for the best.
I'm very happy I've made progress.
I'm now contemplating another question. Should I try and go for equal Vgs's?
That in theory would give me equal Vds's?
Regards,
Dan
Mu - set Iq
bias of lover half - set lower mosfet drain voltage, which is in fact output node voltage
you made it now in a way that you can set it by Papa's recipe, and be done with settings ( though, once finally in complete box, repeat all that with lids closed)
usually is counterproductive trying to be smarter than Mithrandir, when working points are in question; he made it to accommodate most possible scenarios of use ....... and only if you have some extreme wakoo speakers- preamp combination, you can play with his recipe and alter it
bias of lover half - set lower mosfet drain voltage, which is in fact output node voltage
you made it now in a way that you can set it by Papa's recipe, and be done with settings ( though, once finally in complete box, repeat all that with lids closed)
usually is counterproductive trying to be smarter than Mithrandir, when working points are in question; he made it to accommodate most possible scenarios of use ....... and only if you have some extreme wakoo speakers- preamp combination, you can play with his recipe and alter it
I adjusted bias voltage to get a Vds that is as close to 1/2 the rail that I could. But I noticed a heatsink temperature mismatch. My sinks were capable of a bit more heat, so adjusted to get the Vds of the upper/lower fets as close as I could, and bumped the bias up to 3.5A by way of a pot in the upper Mu.
Attachments
damn, it's working!
what next to build?
There will have to be a winter project!
I built the Shade because A) it intrigued me B) I had some monster surplus heatsinks lying around, and C) I had enough capacitors and inductors in the spare parts bin to make a monster 'old school' CLCLC power supply.
I've been waiting on Pa's next VFET because I have some spares.
As soon as I see something 'interesting' I'll start collecting parts!
Regards,
Dan
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