What's the output voltage of full wave rect?

[DaveC]

A full-wave rectified 32vac voltage without filtering or smoothing
components. Just a bridge rectifier connected across a transformer 32v
secondary (no center taps) without a load connected to the output of the
bridge.

What will my DMM read if it's in DCV mode when connected to this output?

Thanks,
Dave

 

[Jasen Betts]

On 2009-12-16, DaveC <invalid@invalid.net> wrote:

A full-wave rectified 32vac voltage without filtering or smoothing
components. Just a bridge rectifier connected across a transformer 32v
secondary (no center taps) without a load connected to the output of the
bridge.

What will my DMM read if it's in DCV mode when connected to this output?

with no capacitors and a cheap average-reading DMM about 28V

Thanks,
Dave

 

[Phil Allison]

"Jasen Betts"
DaveC

A full-wave rectified 32vac voltage without filtering or smoothing
components. Just a bridge rectifier connected across a transformer 32v
secondary (no center taps) without a load connected to the output of the
bridge.

What will my DMM read if it's in DCV mode when connected to this output?

with no capacitors and a cheap average-reading DMM about 28V

** So more expensive DMMs read *OTHER* than average values on their DC
volts ranges??

Do tell.


..... Phil

 

[John Fields]

On Thu, 17 Dec 2009 00:59:02 +1100, "Phil Allison" <phil_a@tpg.com.au>
wrote:

"Jasen Betts"
DaveC

A full-wave rectified 32vac voltage without filtering or smoothing
components. Just a bridge rectifier connected across a transformer 32v
secondary (no center taps) without a load connected to the output of the
bridge.

What will my DMM read if it's in DCV mode when connected to this output?

with no capacitors and a cheap average-reading DMM about 28V


** So more expensive DMMs read *OTHER* than average values on their DC
volts ranges??

Do tell.

---
Funny!

news:1ashi5p1cqgmsccirgseie1osejm8tau7q@4ax.com

JF

 

[DaveC]

with no capacitors and a cheap average-reading DMM about 28V

If a good "True RMS" DMM is used, will the reading be different?

And can you help "teach me to fish" (show me the math)?

Thanks,
Dave

 

[richard]

DaveC wrote:

A full-wave rectified 32vac voltage without filtering or smoothing
components. Just a bridge rectifier connected across a transformer 32v
secondary (no center taps) without a load connected to the output of the
bridge.

What will my DMM read if it's in DCV mode when connected to this output?

Thanks,
Dave

2*sqrt(2)*32/3.14159265=28.8101221484

Integral from 0 to pi of Sin(theta)/pi = Average voltage of Sin(theta) = 2/pi
therefore 1/sqrt(2) rms -> 2/pi
therefore 1 -> 2*sqrt(2)/pi
therefore 32 -> 2*sqrt(2)*32/pi

 

[John Larkin]

On Thu, 17 Dec 2009 00:59:02 +1100, "Phil Allison" <phil_a@tpg.com.au>
wrote:

"Jasen Betts"
DaveC

A full-wave rectified 32vac voltage without filtering or smoothing
components. Just a bridge rectifier connected across a transformer 32v
secondary (no center taps) without a load connected to the output of the
bridge.

What will my DMM read if it's in DCV mode when connected to this output?

with no capacitors and a cheap average-reading DMM about 28V


** So more expensive DMMs read *OTHER* than average values on their DC
volts ranges??

Do tell.

Howzit going, Phil?

A DC-coupled true RMS meter would read different from an averaging
meter.

But in real life, diode leakage and capacitance and transformer
inter-winding capacitance would probably result in an unpredictable
reading.

John

 

[Phil Allison]

"John Larkin"

** So more expensive DMMs read *OTHER* than average values on their DC
volts ranges??

Do tell.

A DC-coupled true RMS meter would read different from an averaging
meter.

** Dogs bark and cat go meow.

But a DC voltmeter is always average responding.

But in real life, diode leakage and capacitance and transformer
inter-winding capacitance would probably result in an unpredictable
reading.

** I have a 4.5 digit meter with true RMS AC ranges (200kHz BW) that can
be DC coupled - a very handy feature.

But one does not use it for the job the OP described without adding a load
resistor, cos of the issues you mention.



..... Phil