bench power supply advice - Page 1
Forum section: electronics / testgear

author: apblog
author_rank: Regular Contributor
timestamp: May 19, 2018, 08:31:58 pm
content: Hi Everyone,I would like to get a power supply to use for powering PCBs on the bench.I have several variable supplies but the problem is that you bump the knob and then the voltage is wrong. This can be catastrophic.Side note: why don't they make bench supplies with a switch so you can turn off the output. That would let you power on the supply, confirm the voltage, and then turn on the output.My requirements are 12@2A, 8V@2A and 5V at .5A. The 8V should be variable.Variable current limiting would be nice but is not a requirement. Voltage and Current meters on each output would be very nice.I know there are computer driven supplies where you can set the voltage and it is difficult to change accidentally. However I don't really trust the computers to not glitch out or forget their settings.Any thoughts on this? Maybe just something I can just pull the knobs off of?Thanks.

author: tautech
author_rank: Super Contributor
timestamp: May 19, 2018, 08:41:45 pm
content: Any good PSU should have a lock function and individual channel switching once you've set the outputs.Check these models out:https://www.siglentamerica.com/power-supplies/spd3303x-spd3303x-e-series-programmable-dc-power-supply/The second image that magnifies shows all the front panel in detail.

author: pigrew
author_rank: Frequent Contributor
timestamp: May 19, 2018, 08:44:23 pm
content: The older HP Mobile Communications Supplies are quite nice (66309B/D, 66311B/D,66319B/D,66321B/D). The '11 & '21 models have a single output which meets your requirements. The '09 and '19 models have a secondary output which goes up to 1.5A.Their keypad has numeric keys as a secondary function, so you can enter numbers instead of turning the knob. The main downside is that the fan can be slightly loud. They have fairly accurate voltage and current readback, too. For remote control, you'd need to use GPIB (a few of the older 66311B units do also have RS-232 control). I got mine for <$200 on eBay.The '19 and '21 units allow you to have continuous sampling of current or voltage over time, in case you need to figure out the total power consumption of your project. Also note that the DVM isn't such a useful option, and requires its negative terminal to be very close to the power supply's common output.I cloned the HP Control software for these supplies (using C# on MS Windows). It definitely needs some work, but would give you a head start if you wanted to write a GUI for them.

author: apblog
author_rank: Regular Contributor
timestamp: May 19, 2018, 08:55:06 pm
content: Tautech,I know you are the Siglent expert around here, a reseller, and occasional critic of the brand. Do you think that this supply can be trusted to not glitch out and destroy expensive prototype boards? I've got a Siglent sig-gen and it can be a little buggy sometimes.Piggrew,Interesting take on those older HP supplies. Thanks.

author: nctnico
author_rank: Super Contributor
timestamp: May 19, 2018, 09:04:24 pm
content: Quote from: apblog on May 19, 2018, 08:31:58 pmIf you have the budget: Keysight E36313A. It is very precise and it has a (unique) low current measurement range so it can measure low currents as well with high accuracy. The latter is part of the reason I bought one.In general the higher end bench power supplies have the possibility to enable/disable the outputs without turning the PSU on & off. Most also have a way to lock the inputs against accidental changing of parameters.

author: MarkF
author_rank: Super Contributor
timestamp: May 19, 2018, 09:05:46 pm
content: Dave did a teardown of the higher resolution version...

author: tautech
author_rank: Super Contributor
timestamp: May 19, 2018, 09:18:41 pm
content: Quote from: apblog on May 19, 2018, 08:55:06 pmCertainly !The X-E is somewhat cheaper and only 10 mA/mV resolution but otherwise both models are the same.They're very quiet and use a smart fan control.There's been criticism of the banana plug socket and very early units had problems with the holes and different ones were fitted. Even recently Siglent US has supplied the new style sockets to owners that have expressed problems here on the forum. There's a thread not long back discussing this issue and the 'spec' of plugs that hold well as it seems some of the old short imperial and US types won't hold properly. They need be ~18mm + long. If yours are like that you won't experience any problems.As you know I watch lots here and I've never seen or know of any failures with these units or mentions of loss or control that might blow a board.Being in a small market I don't sell lots of them but there's enough consistent demand to justify always having some in stock.What model Siglent AWG do you have ?

author: tautech
author_rank: Super Contributor
timestamp: May 19, 2018, 09:30:38 pm
content: Quote from: MarkF on May 19, 2018, 09:05:46 pmYeah and there's been quite a few changes in the nearly 3 years since Dave did that vid.Most of it's mentioned in this thread:https://www.eevblog.com/forum/blog/eevblog-828-siglent-spd3303x-precision-lab-psu-teardown/MostlyManufacturing changesDifferent banana socketsNew GUI and some other FW changes (screensaver deletion ......)

author: apblog
author_rank: Regular Contributor
timestamp: May 20, 2018, 01:14:06 am
content: Quote from: nctnico on May 19, 2018, 09:04:24 pmWow, seriously droolworthy. But the price is a bit much... $1700. If it did actually need all those features I would probably buy it.Quote from: tautech on May 19, 2018, 09:18:41 pmThanks for the info, it's a very tempting choice. I watched the Dave video but haven't made it all the way through the threads yet.I have the SDG2042X. No hacks. Firmware 2.01.01.17R75. I haven't used it much recently but I vaguely recall unexpected behavior with regards to what I see on the output. I have a mental note to always watch the output with a scope.Sadly it's been classified as "funky" in my mind, fairly or not. And colored my impression of what other Siglent gear must be like. But it does get the job done when I need it.

author: tautech
author_rank: Super Contributor
timestamp: May 20, 2018, 01:30:13 am
content: Quote from: apblog on May 20, 2018, 01:14:06 amThat SDG2042X FW is waaaay superseded.You can get the latest version here:https://www.siglentamerica.com/service-and-support/firmware-software/waveform-generators/#sdg2000x-series

author: nctnico
author_rank: Super Contributor
timestamp: May 20, 2018, 09:59:01 am
content: Quote from: apblog on May 20, 2018, 01:14:06 amAnother option is the GW Instek GPE-3323. It checks all your boxes as well, has precise voltage and current readback and it is much cheaper. This one was second on my list.

author: kj7e
author_rank: Frequent Contributor
timestamp: May 20, 2018, 01:39:55 pm
content: For what its worth, I have been using an SPD3303x for the last year almost daily. Its a good supply that does what it claims and meets is specs. I have been happy with it.