Salas hotrodded blue DCB1 build - Page 217 - diyAudio
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Old 24th August 2012, 11:06 AM   #2161
AndrewT is offline AndrewT  Scotland
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dtes,
how do you measure the internal temperature of a transformer?
How do you know if your duty overheats the transformer?
What does the transformer manufacturer tell you about drawing AC current from the transformer?
What does the transformer manufacturer tell you about drawing DC current from the transformer?
It appears you are completely ignoring what the manufacturer tells you about his own product.
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Old 24th August 2012, 11:57 AM   #2162
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Quote:
Originally Posted by AndrewT View Post
how do you measure the internal temperature of a transformer?
with a help of infra-red gun it shows about 50-55c on the surface in non ventilated enclosure.

Quote:
Originally Posted by AndrewT View Post
How do you know if your duty overheats the transformer?
Don't know that actually. The set of IC + Salas reg that I'm feeding requires about 80% of current that is written on the transformer.

Quote:
Originally Posted by AndrewT View Post
What does the transformer manufacturer tell you about drawing AC current from the transformer?
What does the transformer manufacturer tell you about drawing DC current from the transformer?
well..not much info I found.

Quote:
Originally Posted by AndrewT View Post
It appears you are completely ignoring what the manufacturer tells you about his own product.
not on purpose, simply learning on practise from experts' advices and info in the thread, hate books

Anyway, I've got your point regarding toroid!
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Old 24th August 2012, 12:08 PM   #2163
AndrewT is offline AndrewT  Scotland
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and the internal temperature is?

max continuous AC current = VA / Vac when feeding a resistor.
Max continuous DC current = VA / Vac / 1.414 * de-rating factor when feeding a capacitor input filter through a bridge rectifier.
The manufacturer will tell you the de=rating factor for that transformer. Expect it to be ~0.7
This results in a max continuous DC current of ~ half the max AC current.

You must check the manufacturer's data on how to use their product.
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Old 24th August 2012, 12:34 PM   #2164
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understood, Sir!

now I have the feeling that I know everything regarding PS

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and the internal temperature is?
sorry, about 50c is with an open lid of the case, ~55 showed after an hour of operating with a closed one.
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Old 24th August 2012, 02:46 PM   #2165
AndrewT is offline AndrewT  Scotland
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The internal temperature could be at the maximum limit determined by the manufacturer, or below that reliable limit, or worse above that reliable limit.

You have no way of estimating the internal temperature by monitoring the surface temperature.
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Old 24th August 2012, 03:34 PM   #2166
BigE is offline BigE  Canada
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Quote:
Originally Posted by AndrewT View Post
and the internal temperature is?

max continuous AC current = VA / Vac when feeding a resistor.
Max continuous DC current = VA / Vac / 1.414 * de-rating factor when feeding a capacitor input filter through a bridge rectifier.
The manufacturer will tell you the de=rating factor for that transformer. Expect it to be ~0.7
This results in a max continuous DC current of ~ half the max AC current.

You must check the manufacturer's data on how to use their product.
Great... my 80 VA transformer is too small for a hot-rod.
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Old 24th August 2012, 03:37 PM   #2167
AndrewT is offline AndrewT  Scotland
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... my 80 VA transformer is too small for a hot-rod.
That is not what post2157 said.
Quote:
That leaves you with the 80VA 15+15Vac. The maximum continuous output current is ~ 1.3Adc
You will be running the transformer at it's full maximum rating continuously if you draw 1.3Adc from the rectifiers.
1.3Adc is 65times the current consumption of the buffer circuit.
That means you would have 64/65ths of the current throughput of the Salas Reg for "hot-rodding".
Whereas a 80mA DCB1 would have only 3/4 of the throughput as regulator overhead.
That is a mighty big leap into "hot-rodding" territory. Particularly when one considers that 200mA and 600mA are both "hot-rodding" options.
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Last edited by AndrewT; 24th August 2012 at 03:42 PM.
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Old 24th August 2012, 03:38 PM   #2168
BigE is offline BigE  Canada
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Thank you!
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Old 24th August 2012, 03:54 PM   #2169
mjock3 is offline mjock3  United States
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Andrew, I have a 100VA 15+15, what is the max I could safley run the DCB1 at?
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Old 24th August 2012, 07:12 PM   #2170
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mjock3

1.6A it is I suppose if to recapitulate Andrew's suggestion in post 2163.

btw, what settings do you have now?
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