Snort.... No one is more stubborn than Phallus'n. No one. Phil stubbornl y hangs on to an argument when he's been long proven wrong. His stubbornne ss is so well known in fact that he was given a guest cameo on a sitcom. H e's the one on the right. Enjoy:
sage
.com...
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t explain this properly. I have a 24VCT transformer. The transformer need s to power 24VAC equipment as well as 12VDC equipment. For the DC circuit I first tried using a bridge directly off the 24V winding. As soon as I connected up the filter cap the DC output went to 35V, which is probably too high to feed my 12V regulator.
I then realized that I had a center tap that was not being used. So I co nnected my bridge across the center tap and one side of the secondary. Th is time the 13VAC when FW rectified using the bridge went to about 19VDC, which is a safe input to the regulator. Although this worked, I wasn? t happy about unbalancing the transformer this way so I posted my results .
e off the full secondary output with two diodes, cathodes tied together, (typical FW rectifier), and use the center tap as my negative return. I d idn't think that would make any difference in the output voltage from usi ng a bridge without the center tap however I tried it anyway. As I suspec ted it would, the DC output again went to 35V when I connected the filter up.
e is catching up with me. I guess I just don't understand the explanation of how to get a lower voltage to my DC regulator by what I thought sound ed like just configuring the transformer properly. So at the risk of soun ding like a complete idiot here can someone please explain this further? Thanks, Lenny
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Until one of your zener diodes short out (a zener will eventually short out due to inrush current issues is my guess) and you then punch around
19V to the circuit that wants 12....not a good design as a result, more of a hack.John :-#(#
Until one of your zener diodes short out (a zener will eventually short out due to inrush current issues is my guess) and you then punch around
19V to the circuit that wants 12....not a good design as a result, more of a hack.John :-#(#
Well then you want another protection Zener shunted on the 12v line.
Gareth.
board
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o o | | | | to your 24V AC device | | | | | | | | | | | | |,-o---------|----->|-+--+
| | 18DC | +------++ | === === | | /-\ GND | | |'+----------o----->|+----+ ===
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aTwo questions:
Do you have LTSpice?
Can you read alt.binaries.schematics.electronic?
If the answer in no in both cases, get LTSpice.
The .asc files are very handy for this kind of discussion.
?-)
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