# Recommendation on small Ac to DC converter

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#### sircharlton

##### New Member
I'm a new hobbyist. I've been gathering so many parts for a while now and learning on the go. I know I need a bench power supply to test my electronics the beat waya, but does anyone have any recommendations on the cheap $10 open circuit buck down converters to plug in my wall outlet and adjust the voltage (and amps if possible) that works and is less than$20? I see a bunch on the internet for so cheap but would like a professional opinion on which to gey

#### dknguyen

##### Well-Known Member
Just get a wall-wart with adjustable voltage (or even muand something like this to connect it to:

#### dknguyen

##### Well-Known Member
Wall warts don't have adjustable current limits. But they do (or should) have fixed current limits so they don't burn your house down.

Adjustable current limiting instantly makes your power supply shoot up to be about $100 with very few models to choose from. Then another huge price gap where most of them exist which is like$400-500+.

You probably won't blow your circuit THAT much due to overcurrent. And at low current of wall warts it's not like you'll melt anything, even thought you might fry the component. Get a bunch of tiny fuses in different values if you're concerned about that?

#### chemelec

##### Well-Known Member
Most Wall Warts don't have very good Filtering on the DC.
Rarely an Adjustable output Voltage, But some have Fixed Output Voltages available.
Current Limit, Unlikely.
You Could add an LM317 or an LM350 to the output to get an Adjustable current Limit.

#### JonSea

##### Well-Known Member
If you can find an iGo power supply at a thrift store or someplace, you can make an adjustable voltage, adjustable current limit supply. These are still in production I believe.

Details here

Another variable supply I've hacked is a Kensington variable supply. I don't think these are still in production, but if you're lucky enough to find one, there's a lot of potential.

Details here

#### sircharlton

##### New Member
These are great ideas. The wall-wart is probably best, for now. Attaching the lm350 is an awesome idea actually. I ordered a Ac/DC charger with 30w 1.5A adjustable voltage charger. I read the descriptions of the design. It does say it has a current protection. We'll see lol. I need to make one lol

#### chemelec

##### Well-Known Member
These are great ideas. The wall-wart is probably best, for now. Attaching the lm350 is an awesome idea actually. I ordered a Ac/DC charger with 30w 1.5A adjustable voltage charger. I read the descriptions of the design. It does say it has a current protection. We'll see lol. I need to make one lol
What Voltages?

#### Pommie

##### Well-Known Member
You could start with a PC power supply as these are readily available and provide a good starting point for lots of projects. The 5v can power most logic circuits and 12v many higher power circuits. Also, lots of examples on the web how to convert to an adjustable supply.

Mike.

#### KeepItSimpleStupid

##### Well-Known Member
I have tow ideas that both work. Maybe not within your price range, usseful anyway.

http://www.minute-man.com/acatalog/Multi_Voltage_Economical_Power_Supply.html This is available on ebay as well. It only allows fixed voltages and a fixed current limit. It's a nice quiet supp;y that combines an adjustible regulator ans switchable secondaries. It was really good as a battery eleiminator for a transistor radio. The wall wart was useless and too noisy.

Another think I did was to buy off of ebay a cheap DC-DC converter with current limit and voltage selection. It didn't adjust to zero and your inpur has to be 3V above the output. I mounted it in a translucent Hammond enclosure. Red enclosures for RED LEDs. 5.5/2.1 and 5.52.5 are common DC barrel connectors/ I put one of each on the box. The output was an adapt-a-plug (Radio-shack).

The idea was to have an easy way of replacing nearly any wall wart. You need a working 12 V and 24V wall wart. I needed to replace a 6V wall wart and it worked very well. Polarity changes need fidleing.

So, both worked well for fixed supples or should I use the terminology on my Hrrison Labs supply (bought by HP) Fixed voltage power supply; selectable from 0-32 V, That had a 10 A foldback current limiter. Bought broken in the 1980's for like $15.00. Repeaied for$3.00. Manual acquired only a few years ago.
It was used for a long time as a 12V fixed supply for automotive electronics. It had selectable taps.

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