Re: Strange voltage readings=Half-Wave Rectifier?


"Dana" <raff242@xxxxxxxxx> wrote in message news:12hjcsqhvmtts4f@xxxxxxxxxxxxxxxxxxxxx
"Tom Biasi" <tombiasi@********optonline.net> wrote in message
news:qYhSg.75$JF4.48@xxxxxxxxxxxxxxx

"Dana" <raff242@xxxxxxxxx> wrote in message
news:12hjaco8ijtm128@xxxxxxxxxxxxxxxxxxxxx
> "Charles Schuler" <charleschuler@xxxxxxxxxxx> wrote in message
> news:CICdnSEnaJzPOYTYnZ2dnUVZ_rKdnZ2d@xxxxxxxxxxxxxx
>>
>> "ghostwriter" <ghostwriter25@xxxxxxxxxxxxxxxx> wrote in message
>> news:1159296322.379635.88010@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> > Here is the basics, I have a heating coil that I think has a
half-wave
>> > rectifier in front of it (I am still waiting for the sales guy to
call
>> > back). I get about 20Volts AC when measuring the hot wire to ground,
>> > 0.8Volts AC when I measure the COLD wire to ground and 19.2Volts
>> > between the hot and cold wires.
>> >
>> > DC voltage osillates between 1.2 and 1.8 volts. So whatever it is >> > it
>> > inst straight AC.
>> >
>> > I want to be able to calculate the wattage that the system is >> > running
>> > at, any help appreciated. The circuit havs 4.2 Ohemns of resistance.
>>
>> I'd guess 100 watts.
>
> How did you guess that, on the DC or AC
>
>>
>>
>
>
It doesn't matter.

Depending on what the original poster needs, it does. He is stating he
thinks he has a rectifier, well that implies he is expecting a DC output.
And with only 1.8v out, that would probably indicate an issue with the
rectifier.
I assumed he was measuring at the output of what he thinks is the rectifier.
Hence that is where the values he gave come into play.
But if indeed it is just a simple AC heating coil, than yes about 100 watts
would be correct.




He squared the 20 volts and devided by 4 (rounded).
P=E^2/R
If the 4.2 Ohms was operating resistance then I agree with this "guess"


Tom




He stated a lot of things. But the question was of power consumption.
If the unit is getting 20 volts (ACorDC) then the power calculation stands.

If he really cares about the rectifier he shouldn't say " I want to be able to calculate the wattage that the system is running
at, any help appreciated. "

I took all his extra readings to be just info we didn't need but he had no way of knowing what we need.
If the voltage across the heating element is 1.8 volts then that's another story.

Rectifiers before a heating element than has a stepped down supply of 20 volts makes no sense from a design standpoint.

Regards,
Tom

.

Quantcast