120 volt AC to 24 Volt DC?

Question

I have to convert 120 volts AC to 24 volts DC to power a 1/8 horsepower motor. What will I need to get and where can I buy whatever I need?

Answer 1

I thought you already asked this Q, and I answered it. You need a DC power supply which runs on 120V AC, which supplies 24DC @ 5 to 6A. You need 4A for your HP, but starting torque will need a little more.

I'll answer again in about a week....

Answer 2

120 To 24 Volt Transformer

Answer 3

This Site Might Help You.

RE:
120 volt AC to 24 Volt DC?
I have to convert 120 volts AC to 24 volts DC to power a 1/8 horsepower motor. What will I need to get and where can I buy whatever I need?

Answer 4

An 1/8th horse motor is going to require at least 5 amps on 24V...that's some serious current for most 24V supplies, and Radio Shack isn't going to have such brute force 24V supplies.

If you want to do this inexpensively, look into battery chargers for small forklifts, military vehicles (best bet), or diesels. Most older military vehicles still use 24V, and I think a lot of commercial diesels are moving over to 24V. At any rate, you should be able to buy an old 24V charger for maybe $30 this way.

If you don't have luck that way, you could buy your big hoss power supply through Grainger, Digikey, Mouser, etc. but be prepared to pay at least $100. Remember, you'll need a power supply capable of AT LEAST 5 amps at 24V.

The best way to go is to buy a DC inverter/chopper drive for you motor, but such things are expensive ($300 and up). Yeah, not cheap!

Now you see why most motors of any reasonable power rating are 120V and up!

FYI don't try to make your own power supply unless you are pretty good at such things, and for heaven's sake don't try to use a Zener by itself to regulate a high current 24V supply (can you say "Wow, that sure blew up in a hurry!"). Actually, your motor isn't all that sensitive to voltage variation, it'll just slow down or speed up a little.

Another thing remember is to have a good contactor relay to control your motor as an on-off switch, and to have a freewheeling diode to protect said relay/power supply when you interrupt the current to stop the motor. If you don't have either an RC snubber or a freewheeling diode, your relay and/or power supply will be headed for a really early retirement the first time you try to interrupt current (you'll discover why V = dI/dt in a spectacular way). All motor drives have this protecton built in, but power supplies do not!

Answer 5

You need to specify what your going to use this motor for.
If you are going to use it for a long continuous period i.e 1,2,3,4 or more hours. Is the motor fully or partially loaded at start up.
Without the spec i suggest you run it of a 24 volt battery and use your a.c.supply to charge the battery. For this you need a battery charger which you can either you build yourself or buy one from a store. You will still have to decide on the A/hrs required for your battery . Fore 1 hr constant use I would suggest a 40A/hr battery. To charge your battery with a 5 amp 24 volt charger will take about 10hrs.
This is about the best i can do without a spec.

Answer 6

1/8 HP is about 4 Amps at 24 VDC, but the motor may have a higher starting current, so it's wise to buy a larger power supply -- at least 6 amps.

24 volt DC power supplies are a standard commodity item available from many manufacturers, and even from surplus outfits (for 'cheap'). A new one will cost you around $US100 and a surplus unit may be as cheap as 1/4 of the cost of a new unit.

www.Jameco.com is one such "2nd" retailer.

At least one is listed on E-bay, almost everyday -- and they are rarely bid on.



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Answer 7

The easiest thing to do is buy a 24VDC power supply from Radio Shack or the like. To build such you would need a transformer, a full bridge rectifier, and a capacitor.

Answer 8

4:1 step down transformer should get you down to around 30 vac. Next stage build a fullwave rectifier to invert the negative cycle and you should be around 25 vdc give or take. Finally use a zener diode to to trim it down to exactly what you need.

Answer 9

Find you nearest Ham radio operator and ask if they have one or the parts to build one. We tend to have more parts than we need and will usually part with them cheaply. Do put a capacitor across the output to snub the inductive spike generated by your motor starting and stopping.
P.S. If you live near Corning, NY, I'll give you one.

Answer 10

You need a power inverter. See www.trace.com