ebay power supply

[irving2008]

Just some thoughts around the 55v 9.9A power supply I bought off ebay for £22 inc postage as a result of this thread

The two questions being asked were, how do you connect to it and how can the output voltage be reduced below 50v.

The first is easy, standard 4.8/0.5mm LUCAR connectors fit perfectly, so no need for an expensive socket.

The second less so... but I'm working on it. The attached datasheet shows that the Inhibit line must be between 5.5v and 11.5v approx which controls the output voltage between 50 and 57v approx. As the inhibit line drops below 5v the output volts is fixed at 42v until at some point (to be determined) the output is turned off. At 42v the supply is out of regulation (but exactly what that really means is open to experimentation). The circuit diagram below shows one way to set the output voltage.

In the meantime here are some pics.. these are quality supplies..

Pic 1 shows the unit, Pic 2 the connector block.

Pic 3 shows the two main circuit boards when stripped out of the case. Note the substantial heatsinks.

Pic 4 shows the input RFI filter - a sign of quality

Pic 5 shows the daughter board which is a separate switch mode supply to provide internal intermediate voltages. The adjustment does not control the main output volts.

Pic 6 - another sign of quality - a temperature sensor on the main input bridge rectifier heatsink. The 25A bridge rectifier below it converts 240v AC to 330V DC