Request For Good Bench Power Supply Schematics? - Page 1
Forum section: electronics / projects

author: ZeTeX
author_rank: Frequent Contributor
timestamp: March 06, 2016, 08:22:56 pm
content: Hi,Does anybody here have recent (2000+) schematics of good well designed bench power supplys by HP\keysight\rigol\whatever?I'm designing a good bench psu and I want to see how the big companys did it so I can get inspired and learn some things.The schematics I currently have are:1.Agilent E3610A2.Some german psu that is known on the forum.Would gladly appreciate any help, Thanks!

author: MarkF
author_rank: Super Contributor
timestamp: March 07, 2016, 04:46:36 am
content: Not from a company. But take a look at what Peter Oaks put together.

author: prasimix
author_rank: Unknown
timestamp: March 07, 2016, 10:03:39 am
content: Quote from: MarkF on March 07, 2016, 04:46:36 amPlease correct me if I'm wrong but Peter didn't put together anything so far except few videos. It that case Dave'svideosare much more educative. The complete solution that has many interesting details areLiv's PSU. Just to mention a few of them:Pure linear mode of operation (no SMPS in any stage)Sync rectifier"Cascaded" Mosfet pass-elements removed requirement for power relays with multiple tap secondary main transformerDecent precision and good voltage and current range (up to 36V/4A)Additional protection mechanism (beyond default current and voltage limit/programming feature)ARM based MCU digital control (with published source code that includes calibration)USB interfaceI'm using his adopted post-regulation part with single mosfet and it's now in daily exploitation for few months in the raw. Possibly the main obstacle is that is single channel, but it could be easily changed into dual or dual + aux channel solution hosted in larger enclosure. Another think that is missing (in comparison with big brands) is some kind of networking that can be simply added if Ethernet and/or Wifi is sufficient (or even GPIB if connectivity with legacy instrument stack is needed).Liv's biggest "sin" is that he didn't provide any video nor description/measurement on English and his solution simply was lost between thousands of posts on this forum.

author: VK5RC
author_rank: Unknown
timestamp: March 07, 2016, 10:19:03 am
content: How about the older but still going strong HP6632 etchttp://www.keysight.com/en/pd-838596-pn-6632B/100-watt-system-power-supply-20v-5a?pm=PL&nid=-35712.384349&cc=AU&lc=engProverbial Brick Dunny. Also some can act as a load (a bit).

author: IanJ
author_rank: Unknown
timestamp: March 07, 2016, 11:44:06 am
content: Hi,Hardly commercial quality but let me throw mine in the hat for you to pull/learn from. Just another variance on the same old basic design.........but you will see how I isolated the digital side from the 2off isolated analogue channels. Schematic, code etc is on my site.- Arduino powered.- Pre-regulator- Dual channel (isolated)- Dual LCD'shttp://www.ianjohnston.com/index.php/projects/57-project-021-home-built-bench-power-supplyIan.

author: exe
author_rank: Unknown
timestamp: March 07, 2016, 12:39:14 pm
content: Quote from: IanJ on March 07, 2016, 11:44:06 amI always wanted to know why did you choose OP295 that have such a small bandwidth?Also, I remember that the noise was a bit below your expectations. Or above. Did you consider adding, e.g., an RC-snubber across the buck's diode and using "ceramic-friendly" buck IC? And adding a small capacitor between IN and OUT of the buck regulator (like mentioned here:http://cds.linear.com/docs/en/application-note/an136f.pdf)?

author: Kleinstein
author_rank: Super Contributor
timestamp: March 07, 2016, 04:55:50 pm
content: The circuit from IanJ has still some points to improve:- regulation looks like quite slow (slow OPs and Current sense amplifier)- the bias current sink does not work all the way to zero output - this might cause trouble, though likely not a problem with such a slow regulation.- voltage sense from before current sensor (should be directly at the output terminals)- massive capacitive load to U4 B -> could cause trouble, especially if faster OP is used.- rather nonlinear response of current regulation loop- no protection against to much negative U_BE for the output transistors - this might happen at high voltage, capacitive load and a slight overshoot from load drop. Here just a small diode could save the transistors.As a positive point, there is filtering after the preregulator. So there are a few good points, but also bad ones.

author: michaeliv
author_rank: Frequent Contributor
timestamp: March 08, 2016, 12:40:52 am
content: I would also be interested in this. It's surprising that given so many threads about DIY power supplies there are so little options for a complete end-to-end power supply design.

author: Lomax
author_rank: Frequent Contributor
timestamp: March 08, 2016, 01:56:03 am
content: There are good quality schematics, and full BOMs, inthe service manual for my Thurlby Thandar dual 0-30V 2A bench PSU. It also discusses the design and operation of the circuit, and how to calibrate it. The design does use an obsolete chip for the ADC/displays, butthese can be found on eBay...

author: Lomax
author_rank: Frequent Contributor
timestamp: March 09, 2016, 06:48:42 pm
content: Oh and btw,that'll be $5 please.