Need to construct simple voltage regulator circuit

Hi. I thought I might fashion a simple D/C power supply using a surplus switched A/C adapter that used to power my flatbed scanner. It puts out 24 volts @ 0.8 amps.

The plan is to construct a simple voltage divider network using a potentiometer and the necessary passive components with the adapter as input. I used to be able to do this as easily as I write this but that was 30 some yrs ago...

Thank you.

 

Hello Goran,

I'm not really a fan of voltage divider networks via passive resistors because of their inefficiency but they're
the cheapest and simplest.
Attached to this reply is the implementation [in the picture].

Hope this helps.
Regards,
Justin

Thank you Justin. This is not my preferred route either but...it's the cheapest and simplest way as you say.

I'd much prefer, say, an Oltronix power supply with current limitation possibillites for serious lab-work like I had in the day, but...that's in the past and I really don't need that level of sophistication for what I want to do.

Again thanks for taking time with this Justin, it is surely helpful to me:)

You say that you need a regulator circuit. If that is truly the case, there is a problem with the potentiometer method, once a load is put onto the potentiometer, the voltage changes. The effect is small if the load resistance is much greater than the potentiometer resistance, and is obviously dependent on pot rotational position as well (non linear). You will have to monitor the supply with a dvm if you need a specified voltage, and if the load is not constant while running, then that will not be much help either.
If your load current is high, then a simple fixed or variable linear regulator (kit or built up)from places like Ebay(or probably local electronics hobby shops) will be cheaper than a high power variable pot.
Cheers,
Richard

Thanks Richard. I can sort of follow your reasoning, anyway well enough to know that you are right about the output voltage being load dependent.

Hmm...as I had been severely nostalgic for the stabilized Oltronix lab power supplies of my youth and which I mentioned before, I just might go the full distance and buy one.

A one-channel one, 1A max will do fine, yes...Alright - you talked me into it Richard. Done _and_ done. Come monday I'll go to the local electronics shop and pick one up.

Thx for helping me make my mind up;)

You could still use your 24V DC supply, connected to a variable regulator.
There are a lot of kits around, you just have to make sure that they will work at 24V DC in.
A lot cheaper than buying a power supply as described.
If nostalgia and the need for better performance is more important, then.........
cheers,
Richard

_"A lot cheaper than buying a power supply..."_ I know it Richard, and I really don't need lab-level performance but..._"nostalgia..."_ Not to be disregarded;)

Plus, I love the feel and look of a fine piece of professional equipment!

Afterthought: thanks to all friendly ppl who have contributed suggestions and tips for my little project. It is sure heartwarming!

Yes, I'm so silly. What was I thinking when writing this? *sigh*

Sadly, I couldn't delete this reply anymore so my stupidity is etched here forever. Ugh!

I think I'll go with what you said. I'm in a similar problem right now. Thanks for the little piece of information anyway.