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Old 9th October 2005, 03:57 AM   #1
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Default AC to DC converter with selectable voltages?

I guess it was stupid of me to post his in loudspeakers section so I moved it here

I need a AC to DC converter for testing transformers for my ribbons... but I can't seem to find one with selectable voltages...

I need a power supply that will let me run voltages from 0.01mv to 4v while caring a high amperage... say something like 30 amps at 4 volts minimum with the amperage increasing as you go down to 0.01mv

I guess this is a 120w PSU minimum... a 800w one would do my purposes better though

if there's some kind of circuit I can build to do this with a normal transformer let me know

thanks
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Old 9th October 2005, 06:06 PM   #2
anatech is offline anatech  Canada
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Hi Audiophilenoob,
I'm lost. Transformers accept AC and don't like DC current. Same goes for transducers, something that goes down to DC would give you "wind".
Do you want a high current AC source. If so, a Krell amp might work. The big ones can melt the odd Looney (a coin).

-Chris
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Old 10th October 2005, 12:11 AM   #3
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I need it to be DC to test some DC xfrmers I'm using... not for ribbons though... it's for a motor/servo system design

that's why I need it... that and for another project I'm working on

needs to have 1mv-4v selectable with adjusting amperage

if there's some circuit that can do this that would be best... or some product I can buy?
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Old 10th October 2005, 12:28 AM   #4
sss is offline sss  Israel
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that kind of power supply will be very difficult to make by youself

a good pc power supply can supply more then 30A @ 5V
u can add high current regulators and "play" with the voltage...
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Old 10th October 2005, 12:44 AM   #5
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Quote:
Originally posted by sss

that kind of power supply will be very difficult to make by youself

a good pc power supply can supply more then 30A @ 5V
u can add high current regulators and "play" with the voltage...

can you show me an example of a regulator
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Old 10th October 2005, 01:04 AM   #6
sss is offline sss  Israel
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Click the image to open in full size.

this is very simple example of a regulator (dont use that schematic )
to the + u put the desired output voltage , thats the voltage thats gonna be on the load .
the transistor should be very high power in your case , for more then 30A current u must use something like 5 or more high current transistors in paralel , also ,use two or more driver transistors after the op amp ...

also , i dont know exactly what u are trying to do , do u wanna adjust the voltage on the load, or the current?
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Old 10th October 2005, 01:05 AM   #7
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DC Voltage as low as 1mV and of course 0.01mV is a bit unrealistic unless you want to use paralleled electrochemical cells or have efficiency of a fraction of 1%. The weak point is a rectifier.
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Old 10th October 2005, 01:06 AM   #8
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Quote:
Originally posted by sss
Click the image to open in full size.

this is very simple example of a regulator (dont use that schematic )
to the + u put the desired output voltage , thats the voltage thats gonna be on the load .
the transistor should be very high power in your case , for more then 30A current u must use something like 5 or more high current transistors in paralel , also ,use two or more driver transistors after the op amp ...

also , i dont know exacrl what u are trying to do , do u wanna adjust the voltage on the load, or the current?

preferably both voltage and current... where when you decrease vcltage current increases etc... it's like a regulated 500w PSU but you can change the voltages manually

lemme see what I can come up with.... if you have any suggestions on a unit I could modify etc that can already do thist that woudl be way better
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Old 10th October 2005, 01:08 AM   #9
sss is offline sss  Israel
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Quote:
Originally posted by darkfenriz
DC Voltage as low as 1mV and of course 0.01mV is a bit unrealistic unless you want to use paralleled electrochemical cells or have efficiency of a fraction of 1%. The weak point is a rectifier.
true , with currents that high u will have more then 1V on the wires connecting the load , thats why i think he needs a current regulator , not voltage
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Old 10th October 2005, 01:08 AM   #10
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Quote:
Originally posted by darkfenriz
DC Voltage as low as 1mV and of course 0.01mV is a bit unrealistic unless you want to use paralleled electrochemical cells or have efficiency of a fraction of 1%. The weak point is a rectifier.

for the design I would say it's necessary to have that low mv ability

what about 0.001v? I think this is acceptable as the low point

I need it to be selectable... because I need to find the exact voltages this works within
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