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Old 16th February 2012, 05:18 AM   #21
vgeorge is offline vgeorge  Greece
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Here you can see some photos, and what I got from the scope.
I can see a sinewave to the Mhz region.
I am thinking to put a small, like 60p, cap between base collector on the 15030.
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Last edited by vgeorge; 16th February 2012 at 05:29 AM.
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Old 16th February 2012, 06:25 AM   #22
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It's odd..if the parts are correct, try to clean the bottom and try again.
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Old 16th February 2012, 06:47 AM   #23
vgeorge is offline vgeorge  Greece
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I already checked the board, will check again, but both channels behave the same.
What about the small cap?
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Old 16th February 2012, 07:12 AM   #24
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You can try the small caps.. are you sure the pin of your transistor is cbe when looked from the face?
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Old 16th February 2012, 07:24 AM   #25
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how many mA Iq did you set?
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Old 16th February 2012, 07:55 AM   #26
vgeorge is offline vgeorge  Greece
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Yes, I used bc550c and bc560c, they are cbe.
Also be voltages seem OK on all transistors.
Tried small caps no change.
I tried at 100 and 200 mA.
Voltage is around 16V and I have 10000uf and 1ohm before the board.
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Old 16th February 2012, 08:05 AM   #27
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in my testing the voltage is +-12V. maybe you should try a lower voltage? did you get zero average output voltage by adjust the pot?
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Old 16th February 2012, 08:14 AM   #28
vgeorge is offline vgeorge  Greece
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I will try to lower voltage and see.
By adjusting the pot I get near 0 but always a few mV offset. I think this is due to oscillation.
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Old 24th February 2012, 07:40 AM   #29
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Hi Vgeorge,

How's your project going?
Look at mine, I use RE1506 as enclosure. There's still plenty of room for a power board.
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Old 24th February 2012, 07:46 AM   #30
vgeorge is offline vgeorge  Greece
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I was away for a few days.
I will try later with slower output transistors and see.
I have some mje340 I am thinking to use.
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