Help me find a variable +/- 60VDC, 3A, CV/CC power supply - Page 1
Forum section: electronics / testgear

author: heatbreak
author_rank: Contributor
timestamp: July 21, 2016, 12:13:38 am
content: Hello,What's the cheapest way to go about? I thought about getting four cheap 30VDC ps and connected them all in series. Would that work?Here are my wish list1. At least 2 outputs independent outputs. Only one +/- 60 VDC output required.2. Front panel output on/off control3. 10 mV/ 1 mA resolution.4. Digital display.5. Remote digital control.6. Under $700Thanks

author: dxl
author_rank: Regular Contributor
timestamp: July 21, 2016, 07:05:19 am
content: If a used PS is ok, i would use two HP6644A. They are pretty cheap on ebay. Not sure whether they provide 10/mV/1mA resolution though.

author: oldway
author_rank: Super Contributor
timestamp: July 21, 2016, 08:28:37 am
content: For sure, it's not intended for professional use.Quote2 x HP6296A ...add two 5 bucks low cost multimeters for digital displays.

author: BloodyCactus
author_rank: Frequent Contributor
timestamp: July 21, 2016, 12:50:05 pm
content: http://www.tequipment.net/BK9110.html?b=y&v=7690bk 9110, an itech oem psu. $26060V/5A10mV/1mA resolution over the full range

author: Ton
author_rank: Regular Contributor
timestamp: July 21, 2016, 08:16:34 pm
content: You asked for cheapKorad KA6003P, got USB and RS232 interface for external programming, Dave tested it a long time ago (mid2012), the test unit failed, but after some time (late 2012) they fixed the design. recently got a KA3005p at work, took it apart, and it looks much better made than the version Dave reviewedfirst search hit shows 139$http://www.sra-solder.com/korad-ka6003p-programmable-precision-variable-adjustable-60v-3a-dc-linear-power-supply-digital-regulated-lab-gradeElement 14 have them as TENMA 72-2550.Maybe check Korad KA6005P for a little extra head room, but it looks much more expensive (roughly 2x the prise of KA6003P)PS: it still has the annoying bug that it shows setpoint for voltage if voltage is within setpoint-0.2V, else it shows real output voltageTon

author: jpb
author_rank: Super Contributor
timestamp: July 21, 2016, 08:33:00 pm
content: There are a lot of 30V 3A dual supplies that can act as a single 60V 3A supply and these would be easier to find I'd think.It is unclear if the single 60V supply in your spec is just that or a dual supply with one going to 60V.In the UK I'd be looking at the TTi PL series (linear) but in the US they are probably relatively expensive (heavy to ship).

author: heatbreak
author_rank: Contributor
timestamp: July 22, 2016, 12:36:50 am
content: Quote from: Ton on July 21, 2016, 08:16:34 pmThanks Ton. So it's ok to connect four of those in series to get +/- 60VDC?

author: heatbreak
author_rank: Contributor
timestamp: July 22, 2016, 12:38:48 am
content: Quote from: jpb on July 21, 2016, 08:33:00 pmHi jpb, I'm looking to get a single +/- 60VDC supply. Actually +/- 40/50 VDC would be enough. Is it ok to connect four different 30VDC supplies in series to get one single +/- 60VDC supply?

author: Ton
author_rank: Regular Contributor
timestamp: July 22, 2016, 02:09:41 am
content: I am convinced that you could make a +/- 60 V supply out of 4 KA3003P's, but why not use 2 KA6003P's (0-60V, 0-3A) the output is not connected to PE, there is a extra binding post that you can use for tying your output to PE, so it should be stackable (I just haven’t tried it yet with my work units, but I do expect it to work).but why, the price for a KA3003P is around 110$, the KA6003P is around 140$, so much cheaper to go for 2 KA6003P's(prices are from Element 14's equivalent TENMA branded units)one KA6003P for the positive rail, and one KA6003P for the negative rail,the 0V rail would be where you connect the negative terminal from the positive rail supply to the positive terminal from the negative rail supply.http://koradtechnology.com/en/cp3-2.htmlDaves testing1. tryhttps://www.eevblog.com/forum/blog/eevblog-315-korad-ka3005p-reviewfail/2. tryhttps://www.eevblog.com/forum/blog/eevblog-404-korad-psu-followup/end of this forum tread the setpoint voltage vs real voltage bug is described.Ton

author: jpb
author_rank: Super Contributor
timestamp: July 22, 2016, 06:01:45 pm
content: Quote from: heatbreak on July 22, 2016, 12:38:48 amWhat you have to watch out for is the back voltage that may applied to one of the supplies if the circuit being supplied goes short circuit say and one of the supplies turns off because of current limiting, it's not something I've thought about much but it came up in a review of the RS HMC8043-PSU - see page 2:https://www.elektormagazine.com/articles/RS-HMC8043-PSUthe more supplies you have in series the more there are to gang up on a single supply in such circumstances. With say 4 x 30V in series being shorted but only one turning off (so it becomes the new load) then it would see 90V (or -90V) at its output - whether this is ok or not depends on the supply.It would probably be ok if the circuit being supplied had an earth or zero volt rail connected to the centre of the supplies so they weren't just four in series floating. But I'm not an expert.