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 Post subject: How to wire this variac?
PostPosted: Feb Sun 18, 2018 10:31 pm 
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Location: Summitville IN, 46070
I purchased this variac and do not know what tabs to hook up wires to. Could someone help this dummy? :)


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 Post subject: Re: How to wire this variac?
PostPosted: Feb Sun 18, 2018 10:36 pm 
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The input line connects to 2 and 4.

The output line connects to 2 and 3 or 3 and 4 depending on direction of rotation. With either connection, terminal 3 is the "high" side of the output, with the other being the "low" side.

The other two connections provide voltage boost, also depending on rotation;

Install a fuse on the output high side at the rated current. Because of the way Variacs work, it's possible to draw too much current at low output voltage even with input current less than max.

- Leigh

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Last edited by Leigh on Feb Sun 18, 2018 10:41 pm, edited 2 times in total.

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 Post subject: Re: How to wire this variac?
PostPosted: Feb Sun 18, 2018 10:37 pm 
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Location: Albuquerque, NM 87123
2 to neutral, 3 output, 4 hot. 2 and 3 are output


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 Post subject: Re: How to wire this variac?
PostPosted: Feb Sun 18, 2018 10:42 pm 
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Joined: Feb Wed 07, 2018 6:52 pm
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Location: Stone Mountain, GA
If you want 0-140V like most variacs:

input to 2 and 5
output to 2 and 3

2 is common neutral.


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 Post subject: Re: How to wire this variac?
PostPosted: Feb Sun 18, 2018 10:48 pm 
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Location: Summitville IN, 46070
Thank you for such fast replies!


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 Post subject: Re: How to wire this variac?
PostPosted: Feb Sun 18, 2018 10:49 pm 
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SHenion wrote:
If you want 0-140V like most variacs:

140 volts could be dangerous if working on radios designed for 110 or 112 volts.

- Leigh

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 Post subject: Re: How to wire this variac?
PostPosted: Feb Mon 19, 2018 12:03 am 
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Location: Stone Mountain, GA
Leigh wrote:
SHenion wrote:
If you want 0-140V like most variacs:

140 volts could be dangerous if working on radios designed for 110 or 112 volts.

- Leigh
So don't turn it up to 11. ;)

I use it with a dimbulb setup to account for the drop in voltage. That way i can still have near 110V but still keep the protection.

The Hallicrafters I'm working on will not work with the 60W bulb on the dim-bulb setup. It drops to about 75V. I could go out and buy a 100W bulb but easier to just crank it up a to 90V with the variac on 130..


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 Post subject: Re: How to wire this variac?
PostPosted: Feb Mon 19, 2018 1:19 am 
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Here's what I used to hook up mine.


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 Post subject: Re: How to wire this variac?
PostPosted: Feb Mon 19, 2018 2:29 am 
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SHenion wrote:
The Hallicrafters I'm working on will not work with the 60W bulb on the dim-bulb setup. It drops to about 75V. I could go out and buy a 100W bulb but easier to just crank it up a to 90V with the variac on 130..

No radio is intended to work properly on a DBT.

DBTs are not designed to power a working radio.
They're designed to find short circuits and similar wiring faults.

Once they pass that test, replace the bulb with a screw-in fuse and run the set at proper voltage.
You should never run any set on reduced line voltage.
Doing so will tell you nothing, and could damage the set.

- Leigh

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Click "Grebe Stuff" for Synchrophase info


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 Post subject: Re: How to wire this variac?
PostPosted: Feb Mon 19, 2018 4:11 am 
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Is that a dial ring that I see touching your thumb? If so, does it have a voltage scale on it with a pointer on the knob? If the scale goes up over line voltage, you may want to hook it up with the boost connection to make the dial somewhat track. Or, if it only goes to the line voltage, then the non boost connections.


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 Post subject: Re: How to wire this variac?
PostPosted: Feb Mon 19, 2018 6:02 am 
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Greetings to the Forum:

To amplify on J. Hill's comment, many of those dial rings were printed on both sides. One side was calibrated for 0 to 100% line voltage and the other for 0 to 117% (or 130 volts). You mounted the dial scale so that the correct calibration for the intended use was showing.

Regards,

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 Post subject: Re: How to wire this variac?
PostPosted: Feb Mon 19, 2018 9:31 pm 
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Location: Summitville IN, 46070
Yes this indeed does have a double sided scale. It works great now!


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 Post subject: Re: How to wire this variac?
PostPosted: Feb Tue 20, 2018 1:39 pm 
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Leigh wrote:
SHenion wrote:
If you want 0-140V like most variacs:

140 volts could be dangerous if working on radios designed for 110 or 112 volts.

- Leigh

If I am building a variac or powerstat project that may have a use for the higher output voltage, I will include a DPST switch to apply the AC input to either the terminal that produces line in = max volts out, or to the terminal that produces ~140 volts out. The second pole of the DPST switch powers a prominent looking pilot light when the higher voltage position is selected.

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VARIAC BUILD 04 17_01 HV Switching.JPG
VARIAC BUILD 04 17_01 HV Switching.JPG [ 19.91 KiB | Viewed 108 times ]


I also like the types without the extra taps. Nothing extra to be concerned about...


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 Post subject: Re: How to wire this variac?
PostPosted: Feb Tue 20, 2018 4:53 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Maryland 20709, USA
One problem we have on ARF is we know absolutely nothing about the technical background or abilities of new members other than what they tell us.

I will always err on the side of safety in any response I post. Even if it's not needed by the OP, it may yet be useful to others who read the thread or find it in the archives.

- Leigh

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73 de W3NLB
http://www.AtwaterKent.info
Click "Grebe Stuff" for Synchrophase info


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 Post subject: Re: How to wire this variac?
PostPosted: Feb Tue 20, 2018 6:08 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1956
Location: Oswego, NY, USA
Member "comm-nav" wrote above (w/ pictures) about mod's to make a SuperiorPowerstat-brand (or most GenRadVariac) variac ranges switchable. Am writing to inform that this feature is already standard with many models of the STACO branded variacs, and some of the FisherBrand (beige/tan case painted, before Thermo-Fisher) 1960's-80's models spec'd by Fisher, built by Superior company. So if you buy the STACO or older FisherBrand, then you don't have to make this mod, it's already there. Fred


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