25w amp

pudge667 · 30th March 2007, 03:27 PM

i'm building --> http://tinyurl.com/ysamhm
I have one question about the power supply. I have a transformer from which I can get 22V at most. Is it going to be enough to power the amp? I don't need it to work full power. Also, would it be ok to use 2n3055 and 2n2955 instead of bd249 and bd250? Any other modifications necessary in order to use these transistors?

Cheers!

jaycee · 30th March 2007, 04:13 PM

Is that 22V AC, or after being rectified and smoothed by capacitors? 22VAC would give you 31V DC... which might be a bit too high for this circuit (mostly because of Q7 - a TO-126 device such as BD140 should be used here IMO, along with BD139 for Q9)

22V DC would work fine, with only a little reduction in output power.

The page mentions using TIP2955/TIP3055 so yes, the MJ2955/2N3055 pair should work. You could even use transistors like MJ15003/4.

pudge667 · 4th April 2007, 03:08 PM

ok, thx

30th March 2007, 03:27 PM	#1
pudge667 diyAudio Member Join Date: Feb 2006 Location: Under the rain of a thousand flames	25w amp i'm building --> http://tinyurl.com/ysamhm I have one question about the power supply. I have a transformer from which I can get 22V at most. Is it going to be enough to power the amp? I don't need it to work full power. Also, would it be ok to use 2n3055 and 2n2955 instead of bd249 and bd250? Any other modifications necessary in order to use these transistors? Cheers!

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30th March 2007, 04:13 PM	#2
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Is that 22V AC, or after being rectified and smoothed by capacitors? 22VAC would give you 31V DC... which might be a bit too high for this circuit (mostly because of Q7 - a TO-126 device such as BD140 should be used here IMO, along with BD139 for Q9) 22V DC would work fine, with only a little reduction in output power. The page mentions using TIP2955/TIP3055 so yes, the MJ2955/2N3055 pair should work. You could even use transistors like MJ15003/4.

4th April 2007, 03:08 PM	#3
pudge667 diyAudio Member Join Date: Feb 2006 Location: Under the rain of a thousand flames	ok, thx

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