Circuit Specialists Bench PSU - Page 1
Forum section: electronics / beginners

author: tjb1
author_rank: Regular Contributor
timestamp: March 20, 2014, 03:12:45 pm
content: I'm looking for a cheap PSU, I just need to be able to quickly get a voltage. Nothing special at this time as I am just getting started and am a little cautious of all the ebay ones but I have seen Circuit Specialists come up quite a few times here on the forum but nothing directly related to what I am looking at.The PSU I am looking at is this one -http://www.circuitspecialists.com/csi3005sm.html- are there any problems with the cheaper ~$50 units?

author: linux-works
author_rank: Super Contributor
timestamp: March 20, 2014, 04:28:26 pm
content: that's a mastech (or equiv). I have one like it as a spare psu. its fine. nothing high end but it should work ok and probably last a few years. its china designed and built so there may be fake parts inside, used parts, parts that are under-spec'd but that's how it goes today unless you go out of your way to buy top name brand stuff.personally, I prefer older test equipment brand gear and I'll refurb it.but as a starter supply for $50, sure, that should be fine.

author: nanofrog
author_rank: Super Contributor
timestamp: March 20, 2014, 04:29:20 pm
content: You'd be able to get a better supply for the money by buying used quality gear.Basing it on 0-30V, here's a few examples.Kepco ABC 30-0.3HP 6206B(has a broken knob, but should still be usable)AnotherHP 6206BYou'll also be able to get more for the money with multiple output models for ~ double your listed budget. Just need to be patient and do your homework.Examples of triple output units for ~$80 (includes shipping).Kikusui PAB25-1TRTektronix CPS250Something to consider anyway.Hope this helps.

author: tjb1
author_rank: Regular Contributor
timestamp: March 20, 2014, 04:46:17 pm
content: Quote from: nanofrog on March 20, 2014, 04:29:20 pmThat Tektronix looks nice but it concerns me that in the listing it says "Powers on-has not been tested-sold as is", any thoughts on the probability that it may not work?

author: linux-works
author_rank: Super Contributor
timestamp: March 20, 2014, 04:51:54 pm
content: I have a tek cps250. mine works and is extremely clean. and I don't need mine anymore. PM me if you're interested.

author: Bored@Work
author_rank: Super Contributor
timestamp: March 20, 2014, 05:03:23 pm
content: That PSU is a QJE, aka Ningbo JIUYUAN Electronic Co., Ltd PSU.http://www.nbjiuyuan.cn/switching-model/products_30_en.htmlWhile Circuit Specialist usually seems to put some effort into their PSU selection, that particular one is a rather bad pick.Already the 200 mV pp ripple is something you don't really want from a bench PSU. It also has a big set of caps at the output, otherwise the ripple would be even worse. But these caps completely defeat the CC function.

author: cellularmitosis
author_rank: Unknown
timestamp: March 21, 2014, 04:14:42 am
content: If you are referring to the CSI1802X as the $50 one, I've been pretty impressed with what you get for $50. I highly recommend replacing the single turn pots with cheap 10-turn pots.https://www.eevblog.com/forum/testgear/picked-up-a-csi1802x-bench-supply-($50-0-18v-0-2a)/hmm, the forum doesn't seem to detect that link properly. here's a bitly:http://bit.ly/1gZjx8YThe next mod I'd like to try is reducing the size of the output capacitors while keeping the supply from oscillating.

author: BillyD
author_rank: Regular Contributor
timestamp: March 21, 2014, 12:52:48 pm
content: Quote from: tjb1 on March 20, 2014, 03:12:45 pmI have one of those and it's ok for the money. I like the compact size and light weight so basically I use it whenever I need a portable unit.However a couple things to watch out for:- high ripple, as others have mentioned- I've noticed fairly considerable overshoot at power on, although only at very light loads- and most of all: being switch mode, mine has a continuous whine which, for me at least, means I can only tolerate using it for short periods.

author: madires
author_rank: Super Contributor
timestamp: March 21, 2014, 01:47:12 pm
content: I'd recommend a classic linear PSU and not the CSI3005SM which is a switch mode PSU. As already mentioned look for a used one from a known vendor or buy something like a HY3003D. It's not the best PSU but a good value for the money, has a simple circuit (google for diagrams), has common parts and hence simple to repair.

author: Bored@Work
author_rank: Super Contributor
timestamp: March 21, 2014, 01:51:00 pm
content: Quote from: BillyD on March 21, 2014, 12:52:48 pmAh yes, I forgot about the overshot and whining. The one I once had the opportunity to measure had both of these issues, too. The whining does not even come from the main SMPS but an auxilary SMPS inside the PSU. On the other hand the SMPS had a rather dodgy isolation between the mains-carrying switching FET and the heatsink it was mounted on. Excessive thermal paste, but razor thin isolation.My conclusion than was and still is that it is not worth its money. I would save the money and buy something better.If it needs to be a compact SMPS, mike once played with one and was rather happy with it after a few modifications.A similar one is still availablehttp://uk.farnell.com/tenma/72-8345a/power-supply-1ch-36v-3a-adjustable/dp/2216730I think it is a rebadged Mansonhttp://www.manson.com.hk/products/detail/29Just one data point: 50 mV pp ripple vs 200 mV pp ripple of the QJE.

author: zapta
author_rank: Super Contributor
timestamp: March 24, 2014, 04:07:11 pm
content: Quote from: tjb1 on March 20, 2014, 03:12:45 pmThe output post are sunken. You may need to buy an adapter to make it useful with bare wireshttp://www.mouser.com/ProductDetail/Pomona-Electronics/1286/?qs=s%252bX/YkvGCpEsKRI2WlZQlA==