Read posts #149-156
P.S. Marginal dummy, very near to CCS. You should be using something that gives clear headroom. Like 47 Ohm that simulates 175mA load @ 8.17V for 305mA CCS you now got. Its lucky coincidence it now runs on few mA spare.
Changed R1 to 1.5+1 in parallel and 11ohm load. output stays at a bit over 4V and leds won't shine 🙁... Might be that my old homebuilt PSU can't deliver...
Regards
Regards
Yes, I did so. Tried to raise up to 15V - no dice... Stayed a bit over 4V...
I'll check IT over again tomorrow to ensure it still works with lower current.
Regards
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What the feeder supply is made of? Maybe it has a chip reg that heats and limits at 1A you asked it for?
Yes, thanks. This is still voodoo territory for me. I have to read again to comprehend 😛
Regards
Wouldn't surprise me... I believe it's an old 723 based diy from the 70'ties 😀
That's why I'm keen about Frex and Prasimix progress with their PSUs 🙂
Regards
Yepp, thats the way for now. You don't see any problems with the R1 and dummy values as presented? Sure heath must be controlled but 8V @ 1A should work?
Then again the need for 1 amp is only momentaneous at the start of the motor. It will go down when up to speed. So most time it will probably just create heath. Maybe a servo kind of circuit would do better that delivers at demand what is needed and that idles when demand is minute.
Sorry to say I haven't the faintest clue of how to materialize such an circuit.
Regards
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11 Ohm @ 8V = 730mA simulated load. 1//1.5 Ohm = 0.6 Ohm 0.61V/0.6 Ohm = 1.01A CCS. The constant current setting will contain the draw. The IRF9610 M1 will be rather marginal for reliability on now size sink if you will not force cool it. Just monitor the temperatures and do as required.
Sure, monitoring and a fan will do during testing. Heavier sinks for production.
Thank for your answers! 🙂
A variable R1 controlled by the draw of the supplied circuit 🙂. When could this mod be available 😉
If testing is needed give me a bunch of variables to test and document.
Regards
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Thank you very much Salas,
Now I'm in trouble...
After connecting peripheral devices it turned out that my 'receiver' consumes 0.9A (max 1A) current (+5V DC)...
Is there any way to Ref-D give 1A output current? I mean for example 'different' parts, learger heatsink etc.
Is it possible to adjust the schematic to 1 A out. (eg. some part replacement or duplicate some parts etc).
Do ReF-D may work in parallel eg two Ref-D connected parallel to give 0.6+0.6A?
Thanks in advance.
B
There comes a point for higher current circuits that one should abandon Shunt regulators and adopt Series regulators.
Sure, but you would need IRF9530 M1, circa 0.5R R1, and larger external sinks or to force cool the existing ones with a fan. In parallel they would probably work but I haven't tested them in such a configuration.
Sounds true for Class A amplifiers also, but enough hobbyists and a number of legendary audio companies still make them in many Watts and refuse A/B or D.
Enough people are strange about the lengths they would go to when it comes to musical replay delight and thermal inefficiency. Inspirationally strange sometimes.
Right, changed R1 to 0.47ohm to give it a bit more headroom.
After 15min vout is 8.05V temp between fins is 32.7C and ambient 25.4C.
Still 11ohm dummy which gets HOT 🙂
It is a bit sensitive about DC in, if it goes lower than 10.5V then vout starts to go lower as well. If I'm right a 12VAC trafo gives 10.64V rectified? It seems a bit close...
Regards
After 15min vout is 8.05V temp between fins is 32.7C and ambient 25.4C.
Still 11ohm dummy which gets HOT 🙂
It is a bit sensitive about DC in, if it goes lower than 10.5V then vout starts to go lower as well. If I'm right a 12VAC trafo gives 10.64V rectified? It seems a bit close...
Regards
For correct voltage margins read posts #461 & 462. 12VAC trafo should give more if hefty enough to not get challenged by the high constant current draw. Your temperature readings seem low for 1300mA draw. Even with marginal 2.5V Vin-Vout across M1 it dissipates 3.25W. M2 4.58W at 8V with 727mA going to the dummy. Is the thermocouple's end in touch with the sinks metal?
No it isn't. The sinks are just lukewarm - m2 almost cold. I have put some crimptube on the termocouple to avoid shorts 🙂.
Maybe fire up the old scope to see whats happening. The current seems to flow as the dummy gets real hot - untouchable.
Regards
Maybe fire up the old scope to see whats happening. The current seems to flow as the dummy gets real hot - untouchable.
Regards
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Odd. The way you describe it, it can take 1300mA CCS with little over than half of it to the load at 8V and the rest burning inside when still lukewarm. That would make it very easy to handle on the provided sinks even when biased that high. I remember it about 50C with 9VAC trafo, 600mA CCS and 5V out on a 300mA dummy. Either Mike has found the magical iceberg sinks for his minikits or I tested it midday outdoors in Dubai.😀