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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 30th Sep 2014, 7:58 am   #1
sparkymike
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Default Valve chain current?

What is the total current drawn from four valves running at 0.3 amps each?
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Old 30th Sep 2014, 8:05 am   #2
Dave Moll
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Default Re: valve chain current

If they're in series (as implied by "chain"), the total current is 0.3A. Only the voltage is different for the chain and for an individual component thereof. If they were in parallel, the total would be 1.2A (i.e. 0.3A x 4), and the voltage across each component and the whole would be the same.
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Old 30th Sep 2014, 8:08 am   #3
Mike Phelan
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Default Re: valve chain current

Assuming we're talking about them being in parallel, 0.3 x 4 = 1.2 A.
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Old 30th Sep 2014, 10:14 am   #4
sparkymike
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Default Re: Valve chain current?

Yes they are in series. Thanks for help that makes my calculations for a voltage dropper make sense now.
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Old 30th Sep 2014, 11:12 am   #5
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Default Re: Valve chain current?

It would be rare for four 0.3A valves to form a series heater chain. Are you sure?
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Old 30th Sep 2014, 11:19 am   #6
60 oldjohn
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Default Re: Valve chain current?

My Philco U427 peoples set uses a .3A heater chain, What set are you talking about?

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Old 30th Sep 2014, 11:22 am   #7
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Default Re: Valve chain current?

Hi John,
Its a Bestone USA midget radio. Information is so limited that I am drawing the circuit out.
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Old 30th Sep 2014, 11:44 am   #8
60 oldjohn
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Default Re: Valve chain current?

I should have added there is also a Barretter and scale bulb in the chain.
Just seen your last post, I very much doubt you would have a Barretter in your chain.

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Old 30th Sep 2014, 12:26 pm   #9
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Default Re: Valve chain current?

If it's an American midget set, you would be better using a capacitive dropper. There will be considerable heat from a resistive dropper and a .3A heater chain whereas there will be no additional heat with a capacitive type. It all depends on space availability but in this case I would say that the capacitive type is the better option.

Check Paul's calculator for a suitable value. http://www.vintage-radio.com/repair-...per-calcs.html

If you haven't seen it, right at the bottom of the page there is a spreadsheet you can download that does all the calcs for you.
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Last edited by Sideband; 30th Sep 2014 at 12:32 pm.
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Old 30th Sep 2014, 2:29 pm   #10
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Default Re: Valve chain current?

An American radio is more likely to have a 150mA heater chain, unlerss it was intended to run from 32V DC farm supplies.
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Old 30th Sep 2014, 7:01 pm   #11
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Default Re: Valve chain current?

If you have more than one US set best to get a 110V transformer, cheap enough and a good one would give an isolated output.
 
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