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Old 7th December 2012, 07:15 PM   #581
scalpel is offline scalpel  United Kingdom
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Hello Rudi,just a quick question on the build manual.Where do I find it?I checked my email so it's not there.The project will be started in the middle of January so there's no rush.Thanks and best regards,Manuel.
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Old 7th December 2012, 08:12 PM   #582
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Quote:
Originally Posted by AndrewT View Post
Finally, I am really surprised how much difference a few C degrees in device temperature has made to the bias current imbalance. 185mA to 245mA thats 32% difference !!!
It is plausible considering the UBE temperature coefficient (ca. 2,2 mV/K) and the exponential Ic vs UBE law .

Last edited by franzm; 7th December 2012 at 08:14 PM.
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Old 7th December 2012, 08:36 PM   #583
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Jean: if you succeed with step 2 (my post #580): switch power off again, remove the bulb-tester, preset the potentiometer to 0 Ohm
and remove one of the "Bypass - TT-diode" jumpers.
(I see 2 diodes being bypassed on your picture).
You need a string of 5 active diodes for efficient thermal compensation.
Ideally the TT-diode with the highest Vf (did you measure before?) shall be bypassed.

Then: adjust again - and have a big Scotch!

Best regards - Rudi
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Old 9th December 2012, 04:38 PM   #584
lucylu is offline lucylu  England
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Default Case

Hi My case is starting to look very similar to Rudi s,,, I am missing a few parts that should come this week and for one of my shunts that will not work regards john
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Old 10th December 2012, 08:33 AM   #585
lucylu is offline lucylu  England
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After all the problems i had with my shunts i decided i better have one of these
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Old 10th December 2012, 09:04 AM   #586
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This is my bulb-tester, John, and be sure that I use it, whenever I power-on a "new" build.

Best regards - Rudi
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Old 10th December 2012, 12:19 PM   #587
jprco is offline jprco  Canada
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Hi, Rudi. Had a productive weekend. Adjusted both boards without problems finally! (See photos). Now, onto bigger heat sinks and appropriate enclosure. Oh yes, the sound is great and lots of oomphhhhh into 8 ohms. Thanks for all the help on this project. Another great build. Looking forward to the next...
Jean
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Old 10th December 2012, 12:34 PM   #588
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Jean: very nice to see that you replaced the "round" LEDs by square ones to maintain the thermal compound.
Does the ThermalTrak - diode chain consist of 5 active diodes?

It will be very, very hard (at least in my ears) to beat the sound of your FC-100!
So go on and give it adequate heatsinks and a nice case!

Thank you very much for the pictures that you published - I like them!

Best regards - enjoy the sound - Rudi

Last edited by Rudi_Ratlos; 10th December 2012 at 12:42 PM.
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Old 10th December 2012, 03:10 PM   #589
jprco is offline jprco  Canada
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Thanks Rudi. There is just 1 of the MJE0302 shorted on each board so the bias shown is with 5 active diodes - right where it should be just like you said! No need for a BAT42.
I only used the round LED's during the testing of one board.
Off to the heat sink market!
Jean
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Old 10th December 2012, 03:12 PM   #590
jprco is offline jprco  Canada
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Sorry Rudi, I also meant to ask you if they were any of the soft start PCB's left?
If so, I could use 3 more. Let me know.
Jean
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