Hot deal on a used variable DC power supply? - Page 1
Forum section: electronics / testgear

author: TheEternalHermit
author_rank: Newbie
timestamp: July 18, 2013, 05:53:38 am
content: I'm new to electronics (haven't put together any circuits yet) and just ordered a power supply from this seller very similar to the following:http://www.ebay.com/itm/DIGITAL-SOLID-STATE-POWER-SUPPLY-MDL-20500D-GUARANTEED-/200526546973This is the 20500D:I picked up the 20500C because it looked like it had superior adjustment capability.Here is the company but I haven't been able to find any really good info on the one I bought:http://www.eci-info.com/http://val-tec.tripod.com/ECI%20Instruments.htmHere's another page with some info:20500DECI's most popular power supply for general lab use. Designed to withstand use in the classroom, this durable instrument has a three-year warranty.Features:0-25 VDC voltage, 1.2 amp, fixed +5 VDC, 2 amp, and fixed 12.6 VAC, 1 amp center tapped source.Large 3-digit, 7-segment LED display.Flashing LED overload indicators.Short circuit and reverse voltage protected.Overload shutdown protection at 2 amps fixed.All outputs available simultaneously.Anyway, was this a good find for 50$ shipped? And does anyone have any info on the one I bought? How would you rate the quality of these power supplies? They look like they're used in school labs.Edit: It looks like it doesn't include any cables, what kind of cables would I need to buy for this?

author: quantumvolt
author_rank: Frequent Contributor
timestamp: July 18, 2013, 10:26:05 am
content: Imo it is a good deal. As a beginner you will be OK with this rugged all-round power supply.The prices (new) in the links are very high and reflect that the products are intended for schools etc. But they give 3 year warranty even against the abuse you might expect from students in a lab. They also state they have been in business since 1954. Good. I also like the casing and the low voltage AC outlet in the front. I'll rather have your PSU than one of the cheaper Asian ones on eBay.The instrument you bought seems to be the same as the 20500D, but your unit has variable current limit. The 20500D has fixed current limit/shutdown 2 Amp:CI's most popular power supply for general lab use. Designed to withstand use in the classroom, this durable instrument has a three-year warranty.Features:0-25 VDC voltage, 1.2 amp, fixed +5 VDC, 2 amp, and fixed 12.6 VAC, 1 amp center tapped source.Large 3-digit, 7-segment LED display.Flashing LED overload indicators.Short circuit and reverse voltage protected.Overload shutdown protection at 2 amps fixed.All outputs available simultaneously.

author: quantumvolt
author_rank: Frequent Contributor
timestamp: July 18, 2013, 10:40:01 am
content: You can use almost any relatively thick cable with banana plug. Do a search for 'power supply tutorial' or 'lab supply leads' or whatever...Your first project should be to make an add on box for the double 6.3 V AC outlet so you can get a small dual supply for analog ICs. Search '7805 7905 regulator circuit'. Good luck.

author: madires
author_rank: Super Contributor
timestamp: July 18, 2013, 11:25:30 am
content: Quote from: quantumvolt on July 18, 2013, 10:40:01 am6.3V AC calls for tube filaments

author: TheEternalHermit
author_rank: Newbie
timestamp: July 18, 2013, 11:39:22 am
content: Thanks for the reply, as soon as I saw it I sort of bought first and asked questions later. I was worried I might have missed something subtle and that my purchase may have been uninformed. Anyway, I might attempt to build a power circuit like you showed, I know there are lots of DIY power supply kits out there too, I decided those weren't for me.First of all the kits themselves aren't much cheaper than what I bought and to be honest I don't yet feel comfortable soldering something together, sticking it into the mains, connecting wires to it and probing around. I mean if it's done in an electronics class at least the stuff you build there is somewhat under the supervision of a professional. I'll probably just get information on the internet and at some point read 'The Art of Electronics', but pretty much self teach. Not to mention the quality of the equipment you build yourself probably won't be as good for the same price and if you want a digital readout, that's going to be huge hassle for a beginner.