A simple way to verify a regulator's output is with a multimeter

Alan

Administrator
Staff member
Admin
Moderator
Joined
Feb 21, 2025
Messages
382
You've had your ups and downs with regulators, so you always check the output first. What’s your quick method for testing regulator voltage? Do you have any tips to ensure it’s operating smoothly?
 
I like to keep it straightforward just grab a multimeter and check the output voltage.
If it's not right, I know there's an issue.
It's also important to keep the connections clean and tight.
Always start with the basics
 
I've had my share of issues, so now I use a multimeter right after startup. If the voltage isn't stable, I know I need to dig deeper. Plus, I make sure the wiring is solid to avoid any surprises.
 
A quick check with a multimeter does the trick if the output's not in the correct range, I take a closer look at the regulator or the connections. It's a simple step, but it saves me from a lot of trouble later on
 
When I’m working with a circuit on a bench, my ‘scope is always at the ready, and that’s usually the first tool I grab. It not only tells me the voltage, it also shows me the ripple.
 
A real lifesaver for measuring both voltage and ripple in a single sweep.
 
Fortunately, the various linear regulators are pretty stable and don't give us much trouble, but I have seen one or two break into oscillation when the datasheet recommendations are not followed. Still, a multimeter won't show you if you have an unstable regulator. A scope will.

Switching regulators are a different beast, especially mains-driven ones due to the presence of lethal voltages. I have built switchers that in theory worked but in practice burned up transistors so fast I couldn't get a scope on it before the thing fried. At $28 a piece in 1981, these things had to be made of unobtainium. This was for a power supply intended for a satellite, so it had to be reliable. I never did get it to work before I left for a job more to my liking. I wonder i it ever did work... For these beasts a good oscilloscope with a minimum of 100MHz bandwidth is a must. Especially on those high speed GaN converters.
 
Fortunately, the various linear regulators are pretty stable and don't give us much trouble, but I have seen one or two break into oscillation when the datasheet recommendations are not followed. Still, a multimeter won't show you if you have an unstable regulator. A scope will.

Switching regulators are a different beast, especially mains-driven ones due to the presence of lethal voltages. I have built switchers that in theory worked but in practice burned up transistors so fast I couldn't get a scope on it before the thing fried. At $28 a piece in 1981, these things had to be made of unobtainium. This was for a power supply intended for a satellite, so it had to be reliable. I never did get it to work before I left for a job more to my liking. I wonder i it ever did work... For these beasts a good oscilloscope with a minimum of 100MHz bandwidth is a must. Especially on those high speed GaN converters.
Really appreciate you sharing that. Fantastic insight and hard-earned experience.
 
Back
Top