Hi all,
I've got quite a few TIP29A transistors, and would really like to put them to good use in an audio power amplifier. I do have one TIP30 (the PNP version). I've been using them in Darlington configuration with the standard emitter-follower setup, but this only gets me about 500mW of power (and the second transistor heats up quite considerably). I'm looking to get around 2-3W on the output load (8 ohm speaker). Any help would be greatly appreciated.

 

How about posting a schematic?

 

There will be quite a few more things to buy for such an amplifier.

 

See
Models in
http://bordodynov.ltwiki.org/

 

If you want to get 2x3W, 8 ohms, that means:
3W/5V = 0.6A

If you have the board, please put a heatsink on the transistor first, or it will burn and then try to measure the current. It can be that your input is low, so if it gets amplified 10 times, 10x0.005A = 0.050A.

0.050Ax5V = 0.250W.

 

At its maximum allowed continuous current of 1A, a TIP29 and a TIP30 have a minimum current gain of only 15.
A peak current of 1A is an RMS current of 0.71A. Then the power in an 8 ohm speaker is (0.71A squared) x 8 ohms= 4W.
The RMS voltage across the speaker is the root of (8 ohms x 4W)= 5.7V and the peak-to-peak voltage across the speaker is 5.7V x 2.828= 16.1V. The emitter-follower voltage losses of the output transistors total about 4V so a 20VDC power supply must be used.

These output transistors must be driven with peak currents of 1A/15= 67mA.