Regulated DC Power Supply with monitoring of load - Page 1
Forum section: electronics / beginners

author: Antennabuilder
author_rank: Newbie
timestamp: August 24, 2025, 04:05:13 pm
content: I’d like to build a small, adjustable CV DC power supply (itself supplied by an external adapter…say, 24vdc) that can supply anywhere from roughly 1-16V and provide up to 2.5-3A of current, with protection or limiting. My first inclination is to use an LM2596S based step-down converter, but if there are other options, I’d love to hear them. This is all relatively straight-forward, but -The use case would be to power a relay that will be switching on and off, at frequencies ranging anywhere from roughly 50-180hz.I would like to incorporate some kind of microcontroller (PIC, ATMEGA, etc) that can send the following information to a display:- User defined Output Voltage- Measured current draw from the device- Frequency displayed in hz of the device as it is switching on and off- Duty Cycle of the device as it is switching on and offVoltage and current draw metering seem to be straightforward with plenty of information online, however I’m not sure what I should be researching in order to accomplish the second two measurements and have them displayed.Any information is gonna be so helpful, and I like to read, so I definelty don’t need to be hand held. I really just don’t know what concepts and basic keywords I need to be looking for with regard to the hz and duty cycle of a device connected to the power supply.Thanks!

author: Benta
author_rank: Super Contributor
timestamp: August 24, 2025, 07:28:16 pm
content: Lots of PSU designs around, but could you share info on that relay, please?Never heard of such a thing before.

author: Konkedout
author_rank: Frequent Contributor
timestamp: August 24, 2025, 10:43:11 pm
content: RIGHT! Never heard of a relay switching so fast. Maybe not impossible but difficult and a lot of audio noise. Why would anyone want a relay to do that?

author: PGPG
author_rank: Frequent Contributor
timestamp: August 24, 2025, 11:17:12 pm
content: It is not clear what you really want.You write about regulated DC supply providing up to 3A.Then you write about using it to supply relay.Relays I use need no more than 40mA. I can imagine bigger relays but needing 3A? Relay that turns on and engages the starter in a car?Quote from: Konkedout on August 24, 2025, 10:43:11 pmLong time ago (1982) I have made 1 channel oscilloscope. Then wanted to see 2 channels.I had a big relay (like 3x4x10cm) with very delicate relay anchor and two coils to switch it into one or second state (both states were stable). I don't remember frequency I was able to switch this relay but it was enough fast to get the impression of watching two waveforms simultaneously (I had separate trigger input so such asynchronous switching of two signals on the input did not affect the triggering).

author: Antennabuilder
author_rank: Newbie
timestamp: August 25, 2025, 06:11:37 am
content: It would be used for powering a tattoo machine. So not a relay per-se, but not dissimilar from the power supply’s perspective.

author: calzap
author_rank: Frequent Contributor
timestamp: August 25, 2025, 03:38:33 pm
content: Is the tattoo machine switching its coil on and off using mechanical contacts or a solid state mechanism. At that rate, seems like mechanical contacts would wear rapidly. Would like to see circuit diagram of tattoo machine electrics.Mike

author: inse
author_rank: Super Contributor
timestamp: August 25, 2025, 06:57:37 pm
content: Breaker contacts have been standard in gasoline motors for decades.I just wonder what the tattoist will do with the readout you are planning.Wildly jumping numbers of frequency and duty cycle.Over-engineering or real benefit?