Monday, 31 October 2016

Since we're building power supplies...

Following the success of the main power supply for the amp, I decided to improve the USB power supply I'd previously built on a piece of stripboard. The idea of the USB supply is to power the Audio Chromecast which will be feeding into this amplifier. Thus saving the need for a wall-wart.

What's needed is an isolated regulated smooth 5V DC power supply – so a simple circuit powered by the heater AC, containing a rectifier, some capacitors, and a voltage regulator, is all that's needed.

So utilising my newly-acquired PCB design skills, I decided to make my own PCB for this and build the circuit improving on the previous effort. This is the result (the SD card is just a scale prop, since the photos of the previous supply didn't have one I thought it might be a good idea this time)

A bit smaller than the last one.

Tested and working quite happily, it powers the Chromecast and the DC is very smooth.

This is the PCB for it:

Actual size 45 x 35 mm

And changing the subject completely, I thought it might be a good idea to publish a new circuit diagram, since the previous one on here is well out of date by now.
You'll need to click this to see full-size

The circuit diagram however does not show the delay circuit I built with the 555 timer and the relays, so the power supply here is "conceptual" rather than as-built. The relays switch the AC secondaries going into the rectifiers.

Now, the desk-bound work continues - designing the layout of the top, front and back panels, for the CNC machine to cut out.

More later...

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