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Old 5th January 2013, 07:44 PM   #61
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Duncan's power supply simulator is very good for tailoring your power supply down to the desired B+.


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Old 5th January 2013, 08:18 PM   #62
tuhkam is offline tuhkam  Estonia
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This is how the voltages measure right now!
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Old 5th January 2013, 08:28 PM   #63
tuhkam is offline tuhkam  Estonia
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Oh, I completely ignored that I have a high value voltage devider (470k+22k) in the B+ supply. It goes from C2 to ground. It powers the on/off indicator LED.
Not sure if it could contribute to the overheating.

Thanks Soonerorlater, it is a very useful program.
I would need to change the choke to get the voltages up a bit. Would this lighten the burden on the PT?
Experiments with smaller chokes resulted usually in increased hum.
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Old 5th January 2013, 10:18 PM   #64
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Quote:
Oh, I completely ignored that I have a high value voltage devider (470k+22k) in the B+ supply. It goes from C2 to ground. It powers the on/off indicator LED.
Not sure if it could contribute to the overheating.
A useful way to bleed your caps.

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I would need to change the choke to get the voltages up a bit.
A choke of 5-10 H rated at about 100mA would be my choice.

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Would this lighten the burden on the PT?
Choosing a choke with a maximum dc resistance of less than 150r should run cooler than your 500r.

Also for good measure check capacitor C2 is not excessively hot ( again a relative thing ). Inspect for bulging of the body or top.
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Last edited by Soonerorlater; 5th January 2013 at 10:37 PM. Reason: long post
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Old 6th January 2013, 02:04 AM   #65
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I agree with vinylkid. 220u for C2 is sucking big current pulses thro the PT.
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Old 6th January 2013, 07:58 AM   #66
tuhkam is offline tuhkam  Estonia
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Thanks for advice guys! Now I have some things to try.

The C2 is doing ok (no overheating or bulging yet), but I agree 220uF is rather large. I have some 68uF and 47uF I can use.
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Old 6th January 2013, 08:16 AM   #67
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68uf and chokes!
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Old 6th January 2013, 08:39 PM   #68
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turk png.PNG


Here's a rough sim in Duncan giving you similar operating voltages.

Playing around with standard values of C1 can be very informative.

Last edited by Soonerorlater; 6th January 2013 at 08:42 PM.
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Old 7th January 2013, 08:06 AM   #69
tuhkam is offline tuhkam  Estonia
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Lowering the Caps on both sides of the choke to 100u, and the choke itselt to a 330ohm version helped a lot. Now the PT heats up much less.
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