Darlington TIP142 & 147 power amplifier.

Matthewong · 16th June 2009, 02:14 AM

Hi, I found this circuit diagram on internet and I'm interested to make myself one, so I try to make one. First, I have found a version of this diagram using TIP41 as driver transistor. This version is working, just come out a lot of noise and the signal is abnormal when test with oscilloscope. A few days ago, I found another version (90% similar) diagram (pls see the attachment), this version is using TIP 42 as driver transistor. But when my current board change to use the TIP42 transistor, the power amp no longer working and just produce humming sound, I suspect something is wrong with the latest or the second circuit diagram, can anyone help me the rectify it? Thank you.

jaycee · 16th June 2009, 02:16 AM

Looks like the John Tirone amp. Don't bother with it, it doesn't work well.

Matthewong · 16th June 2009, 02:28 AM

is it even modify it, it still won't work well?

teemuk · 16th June 2009, 03:05 AM

This one again?

Isn't production of TIP142/TIP147 even discontinued now?

Matthewong · 16th June 2009, 03:28 AM

Quote:

Originally posted by teemuk
This one again?

Isn't production of TIP142/TIP147 even discontinued now?

is it both tip142 and 147 discontinued already? I still can find it in my country, but don't know any countries still available or not.

llwhtt · 16th June 2009, 03:51 AM

The original amp used a TIP41(NPN) as Q3. The schematic you posted shows a TIP42(PNP) but the symbol is still an NPN. An NPN is usually used in that location, so I'm thinking the TIP42 is wrong. Probably why the amp doesn't work at all now. The schematic shown sure is drawn weird. I redrew it the way most amplifier schematics are drawn and it sure makes it easier to digest. As to the sound or well this amp works I have no idea, just commenting on Q3 and the schematic.

Craig

Matthewong · 16th June 2009, 06:14 AM

Quote:

Originally posted by llwhtt
The original amp used a TIP41(NPN) as Q3. The schematic you posted shows a TIP42(PNP) but the symbol is still an NPN. An NPN is usually used in that location, so I'm thinking the TIP42 is wrong. Probably why the amp doesn't work at all now. The schematic shown sure is drawn weird. I redrew it the way most amplifier schematics are drawn and it sure makes it easier to digest. As to the sound or well this amp works I have no idea, just commenting on Q3 and the schematic.

Craig

Yeah, you are right, just now I also found that the Q3 isn't right, so changed to TIP41, it works. But the signal is abnormal when test with ocilloscope. Don't know what's wrong with it.

sakis · 16th June 2009, 09:05 AM

wana take a look at this

it can describe the darligton problems and why amplifiers working with them can fail very easilly if A Darling.......ton Story .... designed properly

wg_ski · 16th June 2009, 11:56 AM

Quote:

Originally posted by Matthewong

Yeah, you are right, just now I also found that the Q3 isn't right, so changed to TIP41, it works. But the signal is abnormal when test with ocilloscope. Don't know what's wrong with it.

Does it sound bad too, or does the waveform just look all funky? Is anything getting hot?

Could be crossover distortion, oscillating, or the BC558 pair severely out of balance.

Bone · 16th June 2009, 12:26 PM

This was originally designed (thrown together) as a guitar amplifier so don't expect Hi-Fi.

Original site http://members.fortunecity.com/jtfish/amp/ca100.htm

Tony.

16th June 2009, 09:05 AM	#8
sakis diyAudio Member Join Date: Jan 2006 Location: nea makri athens greece	you may wana take a look at this it can describe the darligton problems and why amplifiers working with them can fail very easilly if A Darling.......ton Story .... designed properly __________________ SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr

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16th June 2009, 02:16 AM	#2
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Looks like the John Tirone amp. Don't bother with it, it doesn't work well.

16th June 2009, 02:28 AM	#3
Matthewong diyAudio Member Join Date: Jun 2005 Location: KL	is it even modify it, it still won't work well?

16th June 2009, 03:05 AM	#4
teemuk diyAudio Member Join Date: Nov 2004 Location: Suomi, Finland	This one again? Isn't production of TIP142/TIP147 even discontinued now?

16th June 2009, 03:51 AM	#6
llwhtt diyAudio Member Join Date: Jun 2008	The original amp used a TIP41(NPN) as Q3. The schematic you posted shows a TIP42(PNP) but the symbol is still an NPN. An NPN is usually used in that location, so I'm thinking the TIP42 is wrong. Probably why the amp doesn't work at all now. The schematic shown sure is drawn weird. I redrew it the way most amplifier schematics are drawn and it sure makes it easier to digest. As to the sound or well this amp works I have no idea, just commenting on Q3 and the schematic. Craig

16th June 2009, 12:26 PM	#10
Bone diyAudio Member Join Date: Jun 2004 Location: Dorset, UK	This was originally designed (thrown together) as a guitar amplifier so don't expect Hi-Fi. Original site http://members.fortunecity.com/jtfish/amp/ca100.htm Tony.