This is the fifth part in the Amplifier Project series. This covers the entire process of building an audio amplifier based on the information located at Red Free Circuit Designs. The first four parts of this project are located here:
Amplifier Project – Part 2
Amplifier Project – Part 3
Amplifier Project – Part 4
The transformer has been ordered, the Parts Express power transformer was the best deal, more power and lower price. The Edcor unit was the one I wanted to go with, but they were charging tax and UPS ground would have been $18. Bringing the tax and shipping to over $20. Add in the price of the transformer and it was just too much. Also, with the Parts Express purchase, a couple headphone amplifier kits were added to the order for $10 for my kids to build (that process will be documented here as well).
The focus of today’s work is the power supply circuit. The 4700uf caps arrive a couple weeks ago, those are the first to be added to the board followed by the 100nf. Next, two holes were drilled to mount the fuse holders. Previously, a sharp x-acto knife was used for this type of work, but a pin vise with a drill bit works much better. The one in the picture is a General adjustable pin vise. Not shown is the three holes drilled for the power connector.
A couple bolts hold them in place. Now it’s time to run some wires and solder everything together.
A little hot-glue is used to secure the wires in place. The final assembly step is to add threaded standoffs.
It was tested using my Console 80, it has a center-tapped AC output, 7VAC. The power supply worked as expected, so when the power transformer arrives, the power portion will be completed.