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Discussion Starter · #1 ·
its an electrical tool where i am able to adjust the voltage and the amps to
whatever I want as the output. I plan on connecting 2 electrodes to the end of it. It will be used for testing purposes.


Does anyone know what this electrical tool is called?
 

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A power supply?

You can vary your AC voltage with a Variac but that doesn't exactly give you control over amperage.

I'm not sure I would be able to think of an application where you need to control amperage, short of UL testing - in which case you would be working in a UL listed lab where you would already have this equipment on hand with an up-to-date certification, and wouldn't be asking a DIY site about it..
 

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Thanks for the reply. I recall someone saying once that there is a device for about $250.00 that lets you easily adjust the volts and amperes. It may very well be a power supply that has been tweaked to do this I simply cannot remember the persons name or contact info. I have looked on the internet for the name of such a device but I am afraid I am not well versed in electrical jargon, so I am still searching.
 

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What voltages are you looking for, ac or dc and what are you testing? If we know those things we can direct you better.
 

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Strictly speaking you would be controlling one or the other. What I remember from UL testing on hospital beds is that UL required resistances on the order of micro-ohms between any part of the metal frame on a hospital bed and the ground prong on the plug. To test this, a digital power supply was used and current set to some number - going by memory, it was 20 amps. The voltage readout was read after 5 minutes and had to be 1 volt or under.... I don't remember the exact numbers, in fact I probably am remembering wrong, but I remember that it was the kind of expenditure that would help someone understand exactly how FDA bureaucracy meant that a piece of hospital equipment costs more than the average car.

The fun piece of triva about this was that it had been a UL requirement that had changed within the particular year I was using the requirement. The implication was that the ground wire size that was being used at my company was otherwise adequate for anything the bed went through except for this particular test. These wires were in use on all beds and cost $0.10 to $0.25 depending on length and was used to bond electrically isolated frame sections to eachother. We were replacing a braided copper wire assembly we were buying on the outside at $5 each.

Anyway, because of the increased amperage requirement, we found that we were melting insulation on these ground wires.

Another fun test was static discharge. We charged up 20 kV to a metal plate and touched it to the bed 5 times, then checked to see if the bed still worked. Something like that - that's the UL test. We ran the test on a particular bed, it passed, but the next week during some development work I found that the power board was not far from burning out as a result of the test. Fortunately that particular board was a standard off-the-shelf item we could replace from a Newark catalogue.
 
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Voltage to 100+ watts
Amperes to 20a

DC -- I forgot to include this in my original post.

I will be putting 2 copper electrodes on the end of this device and will be testing liquid such as Water mixed in with other liquids.

I guess I am just unclear what kind of supplier would be in the business of selling this kind of device, am i right by thinking it should be an electrical supplier? I'm not sure who else would have the knowledge of this kind of device.
Like I was alluding... Try looking at electronic suppliers like Allied or Newark, those are two of the major catalogue sources I remember working with.
 
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Thanks for the reply. I recall someone saying once that there is a device for about $250.00 that lets you easily adjust the volts and amperes. It may very well be a power supply that has been tweaked to do this I simply cannot remember the persons name or contact info. I have looked on the internet for the name of such a device but I am afraid I am not well versed in electrical jargon, so I am still searching.
Depending on what you are wanting to do with it. Typically you can find variable power supplies but what you usually get is a variable voltage with a maximum current (current limited based on voltage range). Battery chargers are and example, you can select the voltage and current on some of the higher end ones so they will charge 6VDC, 12 VDC or 24 VDC and different maximum current levels. Try googling variable power supplies. Typically what I've seen is these devices are typically lower voltages, i.e about 50-60 VAC and maybe about 40 VDC.
 
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Discussion Starter · #9 ·
Depending on what you are wanting to do with it. Typically you can find variable power supplies but what you usually get is a variable voltage with a maximum current (current limited based on voltage range). Battery chargers are and example, you can select the voltage and current on some of the higher end ones so they will charge 6VDC, 12 VDC or 24 VDC and different maximum current levels. Try googling variable power supplies. Typically what I've seen is these devices are typically lower voltages, i.e about 50-60 VAC and maybe about 40 VDC.


Thank you, This is exactly what I was looking for -- Variable Power Supply.
 
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