Bench Power Supply? - Page 1
Forum section: electronics / testgear

author: void_error
author_rank: Frequent Contributor
timestamp: April 18, 2016, 03:46:12 pm
content: Hi, I was just looking for a few opinions on a particular Bench Power Supply. Can it be used to power 3.3V/5V digital circuits? What is it good for?Here's picture of it:

author: ledtester
author_rank: Super Contributor
timestamp: April 18, 2016, 09:54:03 pm
content: I don't have any experience with this particular supply, but I think you can get an idea of what to expect by looking at reviews of similar products, e.g.- Amazon reviews/questions for the HY3005D power supply:http://www.amazon.com/Mastech-HY3005D-Variable-Linear-Supply/dp/B000E14F56- This repair video for a HY3005D-3:Even though these are not exactly the same product, I would expect them to have similar design and performance characteristics.From reading the Amazon critical reviews it seems that the HY3005D units are not good for delivering high amps for extended periods of time.This unit can certainly be used to power your typical 3.3V/5V digital circuits. Since it has two adjustable outputs you could set one to 3.3V and the other to 5V if you had a circuit which required both voltages. Another common use for the two outputs is to drive op-amp circuits which require both a positive and negative rail. You can also configure the outputs in series to obtain voltages from 0 to 60 volts (at 5 A), or in parallel to obtain currents from 0-10 A (at 30 V max.)Each output can optionally be grounded. Here's a quick explanation of how that works:

author: void_error
author_rank: Frequent Contributor
timestamp: April 19, 2016, 04:55:09 am
content: Thanks for taking your time to reply.I was expecting a different answer though, being used to other sections of this forum.I actually used one of these (an unbranded one, same thing did sell under many names) and my first reaction was to toss it out the window. Had to take it apart because of one apparently dodgy connection from the PSU board to the front panel. Problem solved after unplugging all the connectors and plugging them back in.Voltage stability seemed ok at first, until you power it up the next day without touching the knobs. Had it set to 9V only to find out it outputs 10V next time it's powered up. I wouldn't power anything that doesn't accept a wide input voltage.Current limit adjustment is off by quite a bit, something to be expected as the input offset voltage of the 741 is not quite small.The circuit inside is very basic, 80's style. Two 741's for each channel, on handling the CV loop, the other for CC. Transformer tap switching is done using a LM324 powered through a 7812 if I remember correctly. Two TO-3 NPN transistors used for the series pass elements.Build quality is awful, the whole thing looks like thrown together in a rush before probably being wave soldered. Took a few pictures while I was trying to fix the problem with one of the channels (the one with the dodgy connector contacts).At the moment the only use I see for this is a large, heavy and expensive paperweight, at least I didn't pay for it. I'll be getting a better power supply, one channel only, digitally controlled in about two days, a much better choice for development.

author: Zbig
author_rank: Frequent Contributor
timestamp: April 19, 2016, 08:58:15 pm
content: Okay... and your point is... ?