How do you change 24VAC to 24VDC?

[fairbro]

Hello

I got a Martin Yale paper folder at auction, but when I got it home, I noticed the power cord was missing. They want $94 for the new power cord. I want to find something cheaper.

Required is an AC-DC adapter, to convert from 110 volts to 24VDC, at 1.2 amps.

The only thing I could find is an adapter that converts 110 volts to 24VAC, at 1.2 amps.

Found many adapters at 24VDC, but the amperage doesn't match, and I don't want to take a chance to mess up the electronics on the paper folder.

So my question is, is it possible there is a device to cheaply convert the 24VAC to 24VDC?

Thanks,

Lindsey

 

[PottedMeat]

Just get a 24VDC @ 1.2A powersupply, they're cheap.

$16

Like this:
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_139096_-1

Datasheet:
http://download.siliconexpert.com/pdfs/2009/5/11/1/47/25/jamco_/manual/139096.pdf

You may have to buy a cheap plug if it doesn't match the one on your machine.

if you really really want to do AC->DC you'll need a diode bridge rectifier and a capacitor.

 

[fairbro]

You must have the new and improved version of Google?

I looked (for days) on EBay, Google, but couldn't find anything.

Thanks

 

[Modular]

Just to add to this (for future reference) the 3 main things that you need to be concerned about with DC are:

1) Voltage
2) Polarity of the connector
3) Amperage of the supply

In the case of 1 and 2, you can't vary. They need to match up with the device that they will be powering. In the case of #3, however, you simply need to make sure that your power supply can give out at least the amperage that the device it's powering requires. You can always use a supply that can give out more amperage than needed, but not vice versa.

 

[Paperdoc]

Forget trying to convert 24 VAC to 24 VDC. Clearly you could not design such a custom power supply, since you had to ask the question. Getting someone else to custom-design this is too expensive. Buying a ready-made device for this (even finding one) is harder and more expensive than doing it the right way.

Just search further for a power supply that can provide 24 VDC at 1.2 Amps or more maximum output from a 110 VAC supply. PottedMeat provided one suggestion. You might have to make some modification to the connector on the end of the unit's output cord to match your folder. If you can't do that yourself, any electronics repair shop could. Sometimes you can get the place that sells you the power supply unit to help with the connector question.

 

[fairbro]

OF course it is easier to do the simple way, but just curious, is it okay to plug, for example, a 9VDC, 2A adapter into a socket that calls for a 9VDC 1A adapter? I have tried to plug in an adapter (for a computer fan) that needed 1A, and the adapter was .5 amp, and that did not work, the fan remained immobile, but no harm was done. But how about if you put in too many mA's, is that going to damage the unit (or the adapter)?

 

[lxskllr]

Higher amperage is fine. The extra capacity won't get used.

 

[pm]

OF course it is easier to do the simple way, but just curious, is it okay to plug, for example, a 9VDC, 2A adapter into a socket that calls for a 9VDC 1A adapter? I have tried to plug in an adapter (for a computer fan) that needed 1A, and the adapter was .5 amp, and that did not work, the fan remained immobile, but no harm was done. But how about if you put in too many mA's, is that going to damage the unit (or the adapter)?

It depends on a whole lot of things - the type of power adapter, the type of circuitry. For example, I have a battery charger that regulates the charge off the size of the power supply, and doubling the amperage rate would pretty much cook my batteries... literally. For most circuitry though - the vast majority - getting too big a power adapter (in terms of amperage rating) is fine, it's too small an adapter that generally causes problems. But I tend to try to match things exactly just to be safe - in case the electronics designer took some sort of short cut somewhere.

 

[fairbro]

Good idea to match exactly.

My DSL unit (from the phone company which was also the ISP wire to my computer) went down because the adapter failed (it was getting no power so I knew it was a bad adapter).

I tried another adapter, which was off by 10% in mA or voltage, I forget. However, that adapter would not turn on the DSL unit. I thought that I had ruined the DSL unit, however, the tech guy at the ISP place gave me another adapter, this one also not a perfect match however it worked.