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Old 6th November 2013, 02:22 PM   #1
maouna is offline maouna  Greece
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Default Regulated PSU for Single supply Amplifier

Hello.i want to build an adjustable regulated PSU for a single supply amplifier.input voltage from the transformer will be about 48V AC ,and after rectification about 66V DC.R12-R13 form a 10K trimmer. 1n5407 rectifier diodes are just for illustration.i will use a 10A bridge rectifier.
A simple schematic found in the forum made by APEXAUDIO is the one below.does it also acts like a capacitance multiplier due to the 100uF cap at base of Q11?are there any small tweaks i can apply?
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Old 6th November 2013, 06:14 PM   #2
maouna is offline maouna  Greece
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this is the schematic
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File Type: jpg psuuu.jpg (59.1 KB, 217 views)
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Old 6th November 2013, 07:20 PM   #3
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I personally would connect a new resistor "R33" from the collector of Q11 to the emitter of Q9. Its purpose is to establish a bias current of approximately 5 milliamperes, flowing in reference diode D8.

I personally would connect a new resistor "R43" from the base of Q10 to the emitter of Q10. Its purpose is to establish a bias current of approximately 0.8 milliamperes, flowing from collector to emitter of Q11.

Finally, I would consider inserting a fuse in series with the transformer secondary, and possibly an EMI-suppressing CRC snubber in parallel with the secondary.
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Old 7th November 2013, 12:00 PM   #4
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Agree.
A simple short circuit protection can also be added in the form of three diodes from Q11 base to Vout.Should give about 3A max current.Otherwise I see no use for R15.
Further small refinements are possible.
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Old 8th November 2013, 11:10 AM   #5
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Forgot this:
It's advantageous to connect R33 to Vout instead of Vin,since hum and ripple is lower and the voltage is more stable.
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