20W Amplifier Project – Circuit Complete

Read the previous entries for this project:

20W Amplifier Project
20W Amplifier Project – Redo
20W Amplifier Project – Prep Work

The remaining components finally arrived, the work can begin on the volume, tone and balance portion of the circuit.  A couple things of note before the work is detailed.  First is that all the components for this project were purchased via eBay (with the exception of the circuit board), primarily from Tayda Electronics.  Good quality and very fast shipping.  Second item of note is that ExpressSCH is the tool used to create the schematic.. it’s free and easy to use.

This part of the project was started by breadboarding the LM1036 and associated components.  Not difficult, but the challenge is all the ground connections which is more difficult on the PCB than it is on the breadboard.

IMG_20140315_082644337 IMG_20140315_085222757
Here’s a short video of the circuit test:

With the circuit test successful, it’s time to mount it on a PCB.  The potentiometers are mounted to the board with all the components for a cleaner installation and shorter Itwire runs (that will hopefully avoid humming sounds).

IMG_20140316_074737434 IMG_20140316_074803858 IMG_20140316_074819171 IMG_20140316_074833428
It’s hard to have a neat wire layout when doing the point-to-point wiring, but it turned out good.  Again, ribbon cable wire was used.  The circuit tested good and now it’s time to mount into the enclosure.  Just need a couple switches for power and input selection, a 3.5mm jack for another input, a chassis mount power connector and some binding posts to complete this project.

Here’s the completed schematic and bill of material for this project:



C1    10 uF 25v
C2    470 uF 16v
C3    2200 uF 25v
C4    100 nF
C5    10 uF 25v
C6    470 uF 16v
C7    2200 uF 25v
C8    100 nF
C9    100 nF
C10    100 uF 25v
C11    47 uF
C12    .47 uF
C13    .01 uF
C14    .22 uF
C15    10 uF
C16    .39 uF
C17    10 uF
C18    .22 uF
C20    .22 uF
C21    10 uF
C22    .22 uF
C23    .39 uF
C24    10 uF
C25    .01 uF
C26    .47 uF


D1    LED


IC1    TDA2003
IC2    TDA2003
IC3    LM1036N


J1    3.5mm Stereo
J2    3.5mm Stereo

Resistors and Potentiometers

R1    220 ohm
R2    2.2 Ohm
R3    1 Ohm
R4    220 ohm
R5    2.2 Ohm
R6    1 Ohm
R7    220 Ohm
R8    680 Ohm 1/2W
R9    47k
R10    47k
R11    47k
R12    47k
R13    47k
R14    47k
R15    47k
R16    47k




Comments please!