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Jed
 
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Default Question regarding AC/DC converter ouput

Hello All!

I recently was looking at a power converter as a possible problem with a
flatpanel monitor.

When I placed a VOM on a 12VDC ac/dc power converter I measured 14 or better
volts. I was hoping someone in here could tell me if this is normal, and if
it is safe with a device that specifies 12V for power input.

I measured several other 12VDC power converters and received higher than the
listed output by 50% in one case (18VDC). It would seem to me that this
would damage a device. Obviously I'm wrong but I would like to understand
why this is.

Any help in understanding this is greatly appreciated!

Sincerely,

Jed
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Ralph Mowery
 
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Default Question regarding AC/DC converter ouput


"Jed" wrote in message
. 125.201...
Hello All!

I recently was looking at a power converter as a possible problem with a
flatpanel monitor.

When I placed a VOM on a 12VDC ac/dc power converter I measured 14 or

better
volts. I was hoping someone in here could tell me if this is normal, and

if
it is safe with a device that specifies 12V for power input.

I measured several other 12VDC power converters and received higher than

the
listed output by 50% in one case (18VDC). It would seem to me that this
would damage a device. Obviously I'm wrong but I would like to understand
why this is.

Any help in understanding this is greatly appreciated!

Sincerely,

Jed


Depends on the device. If it is a big supply rated at several amps or more
and is to run equipment usually ran in a car the voltage is normally set at
13.8 volts. This is the "standard" voltage of a car charging system with
the motor running.

If it is a wall cube, they are not usually regulated. The volage will be
somewhat higher than 12 volts and drop under load to near 12 volts.
If the supply just has a rectifier and capacitor in it and is unloaded it
will be the roughly 12 volts times about 1.4 (peak part of a 12 volt ac rms
reading). Think that 1.4 is close for the multiplier. This is because the
capacitor will charge near the peak voltage of the sine wave.


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Jed
 
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Default Question regarding AC/DC converter ouput

Ralph Mowery uttered with a toothy grin in sci.electronics.repair:

"Jed" wrote in message
. 125.201...
Hello All!

I recently was looking at a power converter as a possible problem with
a flatpanel monitor.

When I placed a VOM on a 12VDC ac/dc power converter I measured 14 or

better
volts. I was hoping someone in here could tell me if this is normal,

....
Depends on the device. If it is a big supply rated at several amps or
more and is to run equipment usually ran in a car the voltage is
normally set at 13.8 volts. This is the "standard" voltage of a car
charging system with the motor running.

If it is a wall cube, they are not usually regulated. The volage will
be somewhat higher than 12 volts and drop under load to near 12 volts.
If the supply just has a rectifier and capacitor in it and is unloaded
it will be the roughly 12 volts times about 1.4 (peak part of a 12 volt
ac rms reading). Think that 1.4 is close for the multiplier. This is
because the capacitor will charge near the peak voltage of the sine
wave.




Thak you!
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