Small/cheap programmable PSU? - Page 1
Forum section: electronics / testgear

author: Per Westermark
author_rank: Contributor
timestamp: June 13, 2022, 03:14:42 pm
content: Anyone know about some smaller and reasonably cheap programmable PSU suitable for automatic testing?Most programmable laboratory PSU are normally quite big and bulky.What I'm interested in is having 5-10 programmable PSU 0-30V and maybe 0-1A per channel and controllable using any of USB, RS-485, RS-232, Ethernet.Either multiple small units or some PSU with maybe 2-4 channels or intended to stack together for arbitrary channel count.Potentially also programmable voltage sources as low as 10-25 mA current capacity for driving stimuli to analogue inputs.No need for lots of fancy displays capabilities.The intention is just to be able to run automatic firmware testing, power save logic, analogue input processing etc for quite low-powerd equipment running supporting 9-30V operation and power consumption in the 1-10W range.Filling the table with many 150-300 W laboratory PSU would be a big waste of space.

author: MLXXXp
author_rank: Frequent Contributor
timestamp: June 13, 2022, 04:15:23 pm
content: If a switching supply is acceptable (considering output noise), something like this might work for you:https://www.aliexpress.com/item/1000004279003.htmlYou would have to feed it with a high enough fixed DC voltage and sufficient current. You might be able to use a single supply to feed all the multiple modules you're looking to have. You also might need a case or panel to mount them in. The company does sell cases for them.I believe the control protocol is documented. I think third party "hacked" alternative firmware is also available.

author: Per Westermark
author_rank: Contributor
timestamp: June 13, 2022, 04:32:23 pm
content: Switched is definitely acceptable. It's only maybe 1-2 channels for testing analogue inputs that might have an advantage of less noise - but equipment for automotive use really can't put much depands on well-filtered input voltages.I'll have to take a look if they looks reasonable - how to control them and any issues with isolation.

author: MLXXXp
author_rank: Frequent Contributor
timestamp: June 13, 2022, 05:34:04 pm
content: Some information on the control protocol:https://sigrok.org/wiki/RDTech_DPS_series

author: MLXXXp
author_rank: Frequent Contributor
timestamp: June 13, 2022, 06:15:56 pm
content: Here the thread for Dave's review of a similar model,https://www.eevblog.com/forum/blog/eevblog-1030-$20-diy-bench-power-supply!/This post links to some fairly good info for communicating with the DPS3005.https://www.eevblog.com/forum/blog/eevblog-1030-$20-diy-bench-power-supply!/msg1319709/#msg1319709

author: Fungus
author_rank: Super Contributor
timestamp: June 13, 2022, 07:05:18 pm
content: There's also these, which come in a finished box:https://www.aliexpress.com/item/1005004242560393.html

author: Per Westermark
author_rank: Contributor
timestamp: June 14, 2022, 06:26:23 am
content: Seems like I should aquire one or two modules and check out. Either using the USB control board or potentially use the internal serial port directly.They are significantly smaller than full-size laboratory power supplies.And seems there are also buck/boost variants, in which case a PC PSU could deliver 12V to lots of modules.Looks like I could have a vacation project.

author: Fungus
author_rank: Super Contributor
timestamp: June 14, 2022, 07:24:01 am
content: Quote from: Per Westermark on June 14, 2022, 06:26:23 amThe USB port on the one I posted goes directly to a CH340 USB-to-serial chip.

author: jeremy
author_rank: Super Contributor
timestamp: June 14, 2022, 08:09:43 am
content: This would let you have 6 channels per unit with ethernet/USB:https://www.envox.eu/eez-bb3/https://www.envox.eu/dc-power-modules/dcm224-power-module/No idea about stock levels though I'm afraid, I know that it uses the dreaded STM32s as the main MCU.

author: Per Westermark
author_rank: Contributor
timestamp: June 14, 2022, 10:02:51 am
content: OK. Because it seems some photos I saw have an external board that is either USB or BT which implies that these boards are connecting to maybe a 3V3 logic-level UART on the main module, in which case one ESP32 could be a WiFi bridge for two power modules.

author: Per Westermark
author_rank: Contributor
timestamp: June 14, 2022, 10:07:18 am
content: Seems the DCM224 would end up a wee bit low on voltage - 0-30V would be needed to do a decent job of looking like a 24V lead-acid battery in a vehicle.But I'm bookmark it - I might have other tasks where this could be a good option.