Cheap, high current, low voltage, programmable power supply?  - Page 1
Forum section: electronics / projects

author: Plasmateur
author_rank: Regular Contributor
timestamp: September 24, 2017, 11:14:26 pm
content: Looking around the internet all day I have yet to find a cheap programmable power supply with the following specsOutput voltage: 5VOutput Current: 50-60AIt seems anything over 30A becomes rather expensive.Here is the cheapest option I've found, but I can't find a programmer's manual with SCPI commands:http://www.cotek.com.tw/product_detail.php?prod_id=JCUzMiMh- this goes for around $350, which is super cheap compared to anything else I've found.Is there a cheap device that exists which allows me to convert a range of high voltages to current? That way I could just buy a cheap programmable power supply with high voltage, and convert it with a some kind of step down transformer to reach a maximum of 60A if needed.

author: pigrew
author_rank: Frequent Contributor
timestamp: September 24, 2017, 11:56:35 pm
content: Power supplies are usually priced by power rating, and you're asking for 300W.One solution may be a used HP 6651A for around $250. I doubt that you'd find a linear supply for much less than that, due to the weight of the transformers.More modern supplies would be switching-topology, but are equally or more expensive (though much lighter and smaller).Another option would be to gang up multiple supplies in parallel. Some of the HP 66xx series supplies support parallel operation.

author: Cerebus
author_rank: Super Contributor
timestamp: September 25, 2017, 12:01:07 am
content: What is the application? That might help to narrow down what to suggest.

author: Plasmateur
author_rank: Regular Contributor
timestamp: September 25, 2017, 12:42:20 am
content: The application is for several large electromagnets whereas I would like some precision over how I go about tuning them. I want high current and low voltage due to safety reasons. I guess I could lower the gauge of the wire, which would kick up the voltage a bit.Another avenue I could take is utilizing a 25V 400Amp power supply I have at my disposal.Each of my coils theoretically have .0455Ohm of resistance.I could put each of them in parallel with the power supply and use variable resistors to tune them, but that could be a huge pain without knowing the exact resistance of the variable resistor. However, it could also be the cheapest option.

author: Vgkid
author_rank: Super Contributor
timestamp: September 25, 2017, 03:40:54 am
content: Look on ebay for a Kepco jqe6-45.

author: tautech
author_rank: Super Contributor
timestamp: September 25, 2017, 04:02:27 am
content: Not programmable as such but what about a cheap SMPS Caddy type DC welder ?

author: Cerebus
author_rank: Super Contributor
timestamp: September 25, 2017, 09:40:52 am
content: Quote from: Plasmateur on September 25, 2017, 12:42:20 amPhysics experiment or mechanics? I ask as the former may indeed require some precision control, whereas the latter you're probably more into the 'a few percent per control step' territory.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 25, 2017, 03:43:12 pm
content: If you are still in the process of choosing the wire, I would consider a thinner wire and thus sightly higher voltage. 12 V and 30 A are easier to get than 5 V and 60 A. Even with 20 V there not much more safety problems than with 5 V. Also current measurement usually gets better at not so high currents.There are sometimes used units. If they don't have digital control, one might consider an external DAC unit. Old units often allow for external analog control.

author: duak
author_rank: Super Contributor
timestamp: September 25, 2017, 04:35:04 pm
content: Plasmateur, there is a device that converts High V Low I to Low V High I - the Vicor VTM current multiplier. It's basically a DC-DC transformer implemented as a switching bridge driving a transformer followed by a synchronous rectifier to convert back to AC. seehttp://www.vicorpower.com/prm_vtmWithin its limits it's quite linear and fairly clean EMI wise.Cheers,