RMI-FC100, a single stage audio power amplifier - Page 128 - diyAudio
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Old 31st July 2013, 09:08 PM   #1271
atupi is offline atupi  Romania
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I think you can order thermaltracks from Mouser or from Onsemi using their sample program in september.
Sk170br you can fing on ebay from reliable vendors.
Contact Rudi, he will give you some nice tips.
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Old 31st July 2013, 10:47 PM   #1272
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Quote:
Originally Posted by hahfran View Post
I happened to read this thread only yesterday. This design seems perfect to drive fast rising broadband speakers. But alas component woes by the number. Thermal track BJTs unavailable and the sK170 only with the GR spec. If I could get some thermal tracks via ebay , could I get along with just 1 pair in the power stage? ( Then a Vbe multiplier is necessary of course)
I can sell you mine if you want,very likly I shall never build my FC100
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Old 10th July 2014, 06:42 AM   #1273
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Simply beautiful.
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Old 10th July 2014, 08:56 AM   #1274
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Mine is sold in the mean time
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Old 7th August 2014, 01:52 PM   #1275
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HI

Do you have the last LTSPICE file ?

Thanks
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Old 30th October 2014, 12:27 AM   #1276
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Default C8, C9

Is it possible to increase the value of either C8 or C9 (both 15pf silver mica caps) on the main board?
The reason I ask is that I mistakenly ordered one 15pf and one 18pf instead of two 15pf. Would using these two be detrimental to the cct design or should it be OK?
If OK, which one should be 18pf; C8 or C9?

Thanks
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Old 30th October 2014, 07:53 AM   #1277
roender is offline roender  Romania
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Quote:
Originally Posted by marcus1 View Post
Is it possible to increase the value of either C8 or C9 (both 15pf silver mica caps) on the main board?
The reason I ask is that I mistakenly ordered one 15pf and one 18pf instead of two 15pf. Would using these two be detrimental to the cct design or should it be OK?
If OK, which one should be 18pf; C8 or C9?

Thanks
The difference is to small to cont. Don't worry ;-)
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Old 30th October 2014, 06:54 PM   #1278
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OK, thanks
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Old 25th March 2015, 04:55 PM   #1279
rotundu is offline rotundu  Moldova
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Default Transistor Matching

Hi Mihai! I am in the process of constructing your amp FC100 and do not quite understand hoe to match output devices - NPN-PNP by hfe - i.e. NPN-PNP - 1 = hfe 1; NPN-PNP - 2 = hfe 2 etc., and the same with vbe? Or, all the devices must have the same vbe and hfe? Please explain. Thank you.

U$1 Q2 NJL0281D Must have the same Vbe +-1mV with the same NPN or PNP with matched hfe
U$2 Q12 NJL0281D Must have the same Vbe +-1mV with the same NPN or PNP with matched hfe
U$3 Q25 NJL0281D Must have the same Vbe +-1mV with the same NPN or PNP with matched hfe
U$5 Q4 NJL0302D Must have the same Vbe +-1mV with the same NPN or PNP with matched hfe
U$6 Q5 NJL0302D Must have the same Vbe +-1mV with the same NPN or PNP with matched hfe
U$7 Q27 NJL0302D Must have the same Vbe +-1mV with the same NPN or PNP with matched hfe
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Old 25th March 2015, 06:28 PM   #1280
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Quote:
Originally Posted by rotundu View Post
Hi Mihai! I am in the process of constructing your amp FC100 and do not quite understand hoe to match output devices - NPN-PNP by hfe - i.e. NPN-PNP - 1 = hfe 1; NPN-PNP - 2 = hfe 2 etc., and the same with vbe? Or, all the devices must have the same vbe and hfe?
YMMV, but in general you will not find both the NPN and PNP with the same Vbe at similar operating conditions - in the case of the NJL/NJW pair above, they will defer by 10s of mV. Also, you will generally find the PNP beta to be higher than the NPN beta at similar operating conditions.
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