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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 21st Nov 2019, 4:02 pm   #1
Bigears
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Default Potentiometer

Anyone know which of the four lugs are for at the back of this Potentiometer
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Old 21st Nov 2019, 4:09 pm   #2
John10b
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Default Re: Potentiometer

If I understand you correctly they are used as an On/off switch.
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Old 21st Nov 2019, 4:24 pm   #3
Kentode
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Default Re: Potentiometer

Stick your multimeter across the contacts and switch the pot on and off until you find continuity/ infinite resistance .

Four contacts probably means DPST, or double pole single throw.
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Old 21st Nov 2019, 6:44 pm   #4
AC/HL
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Default Re: Potentiometer

It looks quite deep, it could be rotary or push-pull. Try both.
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Old 22nd Nov 2019, 6:46 pm   #5
Bigears
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Default Re: Potentiometer

Yes you're right John it's an on/off switch. On the existing Potentiometer, it has two lugs, it has a two-cord mains cable (Brown and Blue) the Brown"Live" goes to one lug of the existing Pot and the Blue goes to the big transformer then from the second lug a red wire goes to the transformer.

My question is it possible just to use one set of lugs as each pair is an on/off switch
which lug would I use for the live ?
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Old 22nd Nov 2019, 8:26 pm   #6
julie_m
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Default Re: Potentiometer

Use a multimeter to work out which switch contacts are connected together when the switch is ON, and use one pair for the live. If you are not switching the neutral (there's no reason to, in the UK, and it's actually very slightly safer not to; although it makes about as much difference in real life as crossing the road to avoid breathing in the smoke from someone else's cigarette) just use either of the two pairs which are connected together when the switch is ON.
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Old 22nd Nov 2019, 8:26 pm   #7
David G4EBT
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Default Re: Potentiometer

It doesn't matter which pair of tags you use for line or neutral.

There are two independent single throw switches which operate simultaneously when you switch the potentiometer on or off. All that matters, is that whichever pole you chose for either line or neutral, must be correctly matched to line and neutral on the output side. IE, to make sure that you don't have one polarity on the input tag, and the other polarity on the output tag.

At risk of stating the obvious, see pic below.

Hope that helps.
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Old 23rd Nov 2019, 1:27 pm   #8
Bigears
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Default Re: Potentiometer

Thanks, Julie and Dave
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