20W Amplifier Project – Prep Work

This is the continuatioin of the 20W Amplifier Project.  The previous two entries can be found here and here.

With the main part of the 20W amplifier assembled and operational, it’s time to focus on control volume.  In the circuit it shows a 10k audio taper pot on the input, which works OK.  It would be better to have not only volume control, but tone and balance as well.  To accommodate this, the TI LM1036 will be added to the design.  A 20pin DIP package that is fairly small and inexpensive to implement.

As all the parts have not yet arrived, there is other prep work that can be started.  An existing ABS plastic case (unused from a previous project) can be used, but the back panel will have to be upgraded from plastic to metal so the amplifier ICs have a heat-sink.  Luckily there was enough material to make both the front and back.  Galvanized steel, .070″ thick will be used.  Heavy and a bit overkill, but functional.  Now to figure out where all the holes need to be drilled!

Amplifier_20W_Prep_1 Amplifier_20W_Prep_2 Amplifier_20W_Prep_3 Amplifier_20W_Prep_4

To utilize existing knobs, the potentiometers will have to be slightly modified so they don’t become damaged when the set screws are tightened.  Easy enough to accomplish, put a bit of zip tie in the slot and it won’t collapse under pressure.

Amplifier_20W_Prep_5 Amplifier_20W_Prep_6 Amplifier_20W_Prep_7 Amplifier_20W_Prep_8

Just need some capacitors and DPDT switches and this project can be completed.


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