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Old 11th May 2004, 11:34 AM   #1
s2kov is online now s2kov  Canada
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Default B+ Voltage

I was building the power supply using the 5AR4 rectifier tube. Using Duncan's PSU2 software, i was expecting a B+ of 300V using below configuration:

232V - 0 - 232V => 22uF => 5H => 47uF

Actual reading on DMM was measured at 329V.

Is the B+ voltage right? It supposed to be lower than that since there is a voltage drop on each plate of rectifier tube.

Appreciate your help....
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Old 11th May 2004, 11:46 AM   #2
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Did you put a load on the power supply?
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Old 11th May 2004, 12:02 PM   #3
s2kov is online now s2kov  Canada
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Not yet.


Quote:
Originally posted by Frank Berry
Did you put a load on the power supply?
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Old 11th May 2004, 12:33 PM   #4
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When you put a load on the supply, the voltage will fall.
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Old 11th May 2004, 12:46 PM   #5
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Hi,

Quote:
i was expecting a B+ of 300V using below configuration:
Having a 329VDC result under no load conditions is only 10% off, not bad in my book.

As our other Frank suggests the voltage will drop with a load attached.

Testing PSUs with no load attached isn't good practice and can be dangerous.

If later on you find to voltage to be off target you can always fiddle a little with the value of the first cap behind the rectifier or try a choke input filter.

Cheers,
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Old 11th May 2004, 01:13 PM   #6
s2kov is online now s2kov  Canada
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Quote:
Originally posted by fdegrove
Hi,



As our other Frank suggests the voltage will drop with a load attached.





Cheers,
Will the voltage drop in the rectifier tube will happen during with load condition?

QUOTE]Originally posted by fdegrove


Testing PSUs with no load attached isn't good practice and can be dangerous.

[/QUOTE]

Oopppsss Thanks for letting me know of this....
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Old 11th May 2004, 03:16 PM   #7
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I see we have 2 Franks here. Pleasant day to both of you.

Kabayan!

Good thing your caps voltage rating wasn't exceeded when you tested your psu without load.

As always, safety first!

Goodluck,
JojoD
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Old 12th May 2004, 03:19 AM   #8
s2kov is online now s2kov  Canada
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JojoD,

Thanks for the reminder. Actually, caps voltage rating was based on VAC * 0.707 calculation but still there are rules that needs to be considered.

Regards.

Andy


Quote:
Originally posted by JojoD818
I see we have 2 Franks here. Pleasant day to both of you.

Kabayan!

Good thing your caps voltage rating wasn't exceeded when you tested your psu without load.

As always, safety first!

Goodluck,
JojoD
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Old 13th May 2004, 01:31 AM   #9
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wow! good thing you were not building a PSU with 420 B+ and 450V caps! without a load, it will....
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Old 13th May 2004, 01:31 PM   #10
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Quote:
Originally posted by arnoldc
wow! good thing you were not building a PSU with 420 B+ and 450V caps! without a load, it will....

That's why I always say to myself. SAFETY FIRST!
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