BD139 / BD140 ?

[wg_ski]

If you are using TIP darlingtons you probably don't need drivers. Regular TIPs you do. The reason you want a half amp driver is because TIPs have the nasty characteristic of having a gain of no more than 20 at rated collector current. May be as low as 10. Driving TIPs as a good job for those 1 watt tall body TO92s, which for the most part are being phased out. Get em now while u can.

 

[anatech]

Those TIP darlingtons can be pretty slow, like any darlinton tends to be. I like the flexibility of separates.

-Chris

 

[jaycee]

Ive used this exact configuration (it's Headphone Amplifier) with MJE15034/5 transistors. If i was going to use it for speakers, i'd probably adapt it to use BC639/640 as drivers.

 

[jaycee]

incidentally, why doesnt he want to use chip amps? Hard to beat the LM1875 for such small applications

 

[U102324]

incidentally, why doesnt he want to use chip amps? Hard to beat the LM1875 for such small applications

Hard to tell, why don't you ask him?

 

[xXBrunoXx]

In the end I bought two LM1875's , has anyone a better schematic than the on in the datasheet + PCB would be nice ! 😀 Thanks guys for your help on this post.

 

[anatech]

You can probably get a PCB on Ebay cheaply

-Chris

 

[jaycee]

Single Chip 25W Amplifier (Project 72) cant get any simpler than that really

 

[xXBrunoXx]

Thank you

 

[xXBrunoXx]

Results

Just from curiosity i have built it. Here is the schematic. 1n4148 is actually a fast diode ( dual in one package , To220 i think ) from a power supply , screwed on the heatsink with the BD's
My " tower " speakers in parallel 3ohm . +-15v rails
Results just before clip :
28hz 3ohm - 5v rms
20hz 3ohm - 4.8v rms
8hz 3ohm - 4.3v rms
100hz 3ohm - 5.4v rms
400hz 3ohm - 4.9v rms
1khz 3ohm - 5.2v rms
5khz 3ohm - 4v rms
10khz 3ohm - 3.5v rms

The power gets down at higher frequency, I would describe it sounding way better than TDA2030 .🙄