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Old 27th November 2012, 03:41 PM   #41
DF96 is offline DF96  England
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The regulator might shut down due to overheating, cool a bit then start up again. Better heatsinking will help, or a resistor to drop some of the voltage and so reduce regulator heating.
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Old 28th November 2012, 12:16 PM   #42
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Thanks for your help. I hope there won't be a problem now it is running cooler.
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Old 28th November 2012, 12:25 PM   #43
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You could try adding a bypass transistor if the problem continues.
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Old 28th November 2012, 01:02 PM   #44
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Quote:
Originally Posted by AndrewT View Post
CCS drive for the heaters does not suffer from current surge at start up.

Another approach is slow start up of the LM317.
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Old 28th November 2012, 04:40 PM   #45
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Don't run the Signal Ground to the junction between the smoothing capacitors.
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Old 28th November 2012, 05:27 PM   #46
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Yes, and don't run all the reservoir and smoothing caps grounds to a star point - unless you enjoy listening to buzz. Signal ground should connect to the PSU output, not some internal point full of charging currents.
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Old 29th November 2012, 01:46 PM   #47
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Another approach is slow start up of the LM317.

It's been pointed out to me thatthis diagram may have errors.

D6 the LEd is shown the wrong way round.

It is a simple use of the datasheet diagram attached below.
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Old 29th November 2012, 07:12 PM   #48
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its funny how many strange things you find when you start to study something

just now I found a LM337T listed to take -50V input I guess it must be a mistake
but also now wonder how many mistekes there are
for one, many of the regulators seem to have different specs
wonder how many od variations there are
some numbers just look weird because of different packing codes
but some have attached a letter that are not in the specsheet

also, on my own special matter, I can find the LM317HVT, but the LM337HVT seem to be a problem
could it be that the negative reg have had reliability issues with this higher voltage ?
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Old 29th November 2012, 07:32 PM   #49
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by KatieandDad View Post
It's been pointed out to me thatthis diagram may have errors.

D6 the LEd is shown the wrong way round.

It is a simple use of the datasheet diagram attached below.
just now seen one looking 100% exactly like that
besides, any simple adjustable reg seem have a diode oriented that way
the neg reg would be turned opposite way
so if its a neg regulator you need I guees its the wrong schematic
its interesting with this 'softstart' for tube amp bias
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