hello there.
just a few minutes ago, i decided to measure my DC offset on my mains but what i got is....
-15VDC!i measured every power plugs in my house and the results remains the same!
how come my mains becomes sh*tty like this?.what caused something like this?
i measured the DC offset since i heard some noises from my speakers btw.
no, it's not the DMM fault.i'm sure it's not.i measured my amp DC offset, DC supply, everything and i always got a good result.battery also new.
should i call the power provider and tell them about this high DC offset?
don't mind the stuffs on my table.couldn't get better spot
just a few minutes ago, i decided to measure my DC offset on my mains but what i got is....
-15VDC!i measured every power plugs in my house and the results remains the same!
how come my mains becomes sh*tty like this?.what caused something like this?
i measured the DC offset since i heard some noises from my speakers btw.
no, it's not the DMM fault.i'm sure it's not.i measured my amp DC offset, DC supply, everything and i always got a good result.battery also new.
should i call the power provider and tell them about this high DC offset?
don't mind the stuffs on my table.couldn't get better spot
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It is very strange, I think.
Should you measure of your amp's tranny at secondary AC side.
Is there any DC?
If yes, I think your DMM fools you.
Because you wrote above, you measures only DC levels, which are correct.
Regards,
Gyuri
Should you measure of your amp's tranny at secondary AC side.
Is there any DC?
If yes, I think your DMM fools you.
Because you wrote above, you measures only DC levels, which are correct.
Regards,
Gyuri
the secondary measures -1V 😕
i guess i'll ask my friend for another DMM..
it's strange if the DMM fools me since i measured AC gain and DC offset of my amp and they measures good
i guess i'll ask my friend for another DMM..
it's strange if the DMM fools me since i measured AC gain and DC offset of my amp and they measures good
I'm just curious, so I've measured my AC line.
I have three DMM, all of them measure DC on my mains below 1mV.
When my daughter drying her hair, the dryer causes about 0,4VDC on my power line.
It is causing mechanical hum in toroids.
15VDC too high to be true.
Kind regards,
Gyuri
I have three DMM, all of them measure DC on my mains below 1mV.
When my daughter drying her hair, the dryer causes about 0,4VDC on my power line.
It is causing mechanical hum in toroids.
15VDC too high to be true.
Kind regards,
Gyuri
like 6 months ago, my DC mains were around 1V with any DMM.and now i doubt if it's really -15VDC..i'll report maybe 2~3 weeks later since i should leave my room >200km far 😀
idk if my xformer rattling or not since i bolt him pretty tight
idk if my xformer rattling or not since i bolt him pretty tight
Meters are not designed to measure small amounts of DC in the presence of large amounts of AC. You need to use a mains-safe low pass filter. Don't do this unless you are completely confident about understanding it.
You may find this of interest....
How DC Appears on the Mains
Mains DC and Transformers
Another really informative item from Rod Elliot's site
And it mentions hair dryers too!
How DC Appears on the Mains
Mains DC and Transformers
Another really informative item from Rod Elliot's site
And it mentions hair dryers too!
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@df96
got it.so, the LPF for mains is like a line filter or different?..it passes below 50/60Hz, right?
@kimbo
thanks!.i tried the rod elliot way but somehow the DC still appeared.and the diode went darn hot..
got it.so, the LPF for mains is like a line filter or different?..it passes below 50/60Hz, right?
@kimbo
thanks!.i tried the rod elliot way but somehow the DC still appeared.and the diode went darn hot..
Is it possible, that you really have a 15VDC component on your mains?
I can't believe!
I have measured a nice tranny's DC resistance, it was 2Ohm.
That DC level could heat it about 112W if am I correct.
I don't know my DMMs how correct at this circumstances.
But I get cc. same measurements with hair dryer on low power settings with all of them,
it is about 1.2-1.4VDC, if I connect it near the measurement point.
I more or less trust in my METEX M-4650CR.
You know I'm not an expert, so I'm curious, what think about this who is an EE mind.
I can't believe!
I have measured a nice tranny's DC resistance, it was 2Ohm.
That DC level could heat it about 112W if am I correct.
I don't know my DMMs how correct at this circumstances.
But I get cc. same measurements with hair dryer on low power settings with all of them,
it is about 1.2-1.4VDC, if I connect it near the measurement point.
I more or less trust in my METEX M-4650CR.
You know I'm not an expert, so I'm curious, what think about this who is an EE mind.
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now i really doubt about my measurement.i'll try to get another DMM, and report the result here as soon as possible.
i also dont really know why..but i swear they makes my precious finger red as red as steamed crab.
or the load was too big for the KBPC3510 diodes? 😕
the load was around..um..how much 2 pairs BJT biased around 1.5A on +-30VDC + 2 pairs mosfet on 300mA @ +-30VDCdissipate? 😕 (im such a dumb)
or the load was too big for the KBPC3510 diodes? 😕
the load was around..um..how much 2 pairs BJT biased around 1.5A on +-30VDC + 2 pairs mosfet on 300mA @ +-30VDCdissipate? 😕 (im such a dumb)
I've built this one for 120VAC and measured the DC component across the device, as mentioned in the article. (The highest DC reading I ever got was in the 3V range, when our printer woke up.) Try it, and report back?
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