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Old 13th October 2014, 09:02 PM   #1
JBLman is offline JBLman  United States
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Talking How to use this transformer with tube rectification

I have an r core transformer laying around and have good luck using it with a full wave bridge. But now I'm looking into replacing the bridge with a tube rectifier (274b) here's a link to the transformer:
https://tubedepot.com/products/r-cor...er-transformer
I know I need a ct on sec. #1 and sec. #2 is there a way for me to add it into the circuit?
Any help would be great as I don't want to use the Hammond or a toroidal transformers.
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Old 13th October 2014, 09:17 PM   #2
rayma is online now rayma  United States
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Quote:
Originally Posted by JBLman View Post
I have an r core transformer laying around and have good luck using it with a full wave bridge. But now I'm looking into replacing the bridge with a tube rectifier (274b) here's a link to the transformer:
https://tubedepot.com/products/r-cor...er-transformer
I know I need a ct on sec. #1 and sec. #2 is there a way for me to add it into the circuit?
You do need a center tap for using two rectifiers per secondary. Without a center tap, you can use a full wave bridge by adding two more rectifier tubes.
The usual dual rectifier tubes have a common cathode, so you need two more separate tubes to connect their anodes instead of their cathodes for the second pair.
The filament winding normally uses silicon diodes, though.
http://www.hammondmfg.com/pdf/5c007.pdf

Last edited by rayma; 13th October 2014 at 09:28 PM.
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Old 13th October 2014, 09:42 PM   #3
JBLman is offline JBLman  United States
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Isn't there a way to just make the center tap? Without all the extra hardware ( more tubes and diodes)?
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Old 13th October 2014, 10:14 PM   #4
kevinkr is offline kevinkr  United States
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No, the simplest way would be to implement a bridge using a pair of silicon diodes (UF4007) for example and your 274 rectifier tube. Google hybrid graetz bridge for more details.
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Old 14th October 2014, 12:13 AM   #5
rayma is online now rayma  United States
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Originally Posted by kevinkr View Post
No, the simplest way would be to implement a bridge using a pair of silicon diodes (UF4007) for example and your 274 rectifier tube. Google hybrid graetz bridge for more details.
Yes, and this will still give you a soft start.
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Old 14th October 2014, 01:20 AM   #6
AJT is offline AJT  Philippines
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Quote:
Originally Posted by JBLman View Post
I have an r core transformer laying around and have good luck using it with a full wave bridge. But now I'm looking into replacing the bridge with a tube rectifier (274b) here's a link to the transformer:
https://tubedepot.com/products/r-cor...er-transformer
I know I need a ct on sec. #1 and sec. #2 is there a way for me to add it into the circuit?
Any help would be great as I don't want to use the Hammond or a toroidal transformers.
the traffo you are eyeing has secondaries not suitable for your requirement...https://d1sjrnpi226dnf.cloudfront.ne...pdf?1382030398

while it is possible to use secondary #2,it is rated for 3A and the 274 needs just 2A, you will have to use a dropping resistor,about 1ohm/10 watts.... center tap is not possible...although you can put two 56 ohm resistors on either side of the filaments to mimic a center tap...
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Old 16th October 2014, 02:17 PM   #7
JBLman is offline JBLman  United States
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Thanks guys for the help! Much appreciated! I did just stepperated the filament with a small 5v 2a ct transformer solved all the problems.
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Old 21st October 2014, 06:27 AM   #8
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very nice posttttttttttt






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Old 21st October 2014, 07:10 PM   #9
JMFahey is offline JMFahey  Argentina
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Avoid that transformer like the plague.

It was designed for 100V mains, you have nominal 120V which often reaches 127V

Normal design expects and stands +/- 10% ... which would mean 110V tops ... you can easily have 27% more.

Overvoltage beyond a certain point (which you will surpass) dramatically increases core saturation and loss, there's many threads on that.

It's irresponsible for Tube Depot to sell them and shrug off "you can use them with no problems"

Even the 6.3V filament voltage is wrong by a lot ... 7.6 V AC .

Don't be blinded by the apparent low cost.
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Old 21st October 2014, 11:57 PM   #10
AJT is offline AJT  Philippines
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Even the 6.3V filament voltage is wrong by a lot ... 7.6 V AC .
it is possible that when the traffo is loaded, that voltage can drop to 6.5v or so...
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