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 My first project Variac

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FrankB
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FrankB


Join date : 2010-11-22

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PostSubject: Re: My first project Variac   My first project Variac I_icon_minitimeNovember 25th 2012, 11:48 pm

Cliff-
Do NOT ground the variac to the isolation tx output socket as shown in the schematic. Shocked
That totally defeats the purpose of the isolation transformer. You might as well use the variac without the transformer.
Key word here is "isolation".
NOTE: THis pertains if you use anything with a 3 wire cord or has the neutral grounded to the power cord ground.

I found this out the hard way in tech school many decades ago. Sad
If you try to scope a piece of equipment plugged in with the ground hooked up you will either blow up the equipment, blow up the scope or other test equipment you are using, or blow the circuit breakers in the building.

The teacher knew nothing about "hot chassis" setups :evil: and after plunging the entire building & several classrooms into darkness 3 X in a row, I finally figured out what was going on.
Not to mention you can fry your self easier also.

I typically use a Weller grounded tip soldering iron for repairs and with the 3 wire cord and the ground in place, I have made some mighty fine arcs with the soldering iron to a hot chassis even with the power switch "off", when the hot chassis is plugged in wrong, or if there is leakage thru the isolation line bypass caps inthe item under repair.
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Cliff Jones
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Cliff Jones


Join date : 2010-11-22

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PostSubject: Sad News   My first project Variac I_icon_minitimeJune 5th 2012, 5:40 pm

lol! I did get a General radio Variac with two meters, one is voltage and the second has two ranges in watts, with the maximum being 1400W. So my project will be put on hold for now. (I May have mentioned this in another post, but I fergit Sleep Question

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Cliff Jones
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Cliff Jones


Join date : 2010-11-22

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PostSubject: Just picked up 500 coin envelopes   My first project Variac I_icon_minitimeApril 21st 2011, 5:36 pm

Decided to store my caps and resistors that way, went to Office Depot to get my computer memory, and off handedly asked if they carried coin envelopes, $ 19 for 500 count, guess another project now. No No No 🤡

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Cliff Jones
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Cliff Jones


Join date : 2010-11-22

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PostSubject: Re: My first project Variac   My first project Variac I_icon_minitimeApril 21st 2011, 5:28 pm

I'm not a woodworker per-say but I guess I have to cobble a box together, getting some wood from ACE Hardware Or a Metal box. I do Have a small bench top Drill press and a Radial arm saw in the garage, so one way or the tuther, I'll get something going. Ive tried to make a diagram now I'll have to figure out the parts layout next. Rolling Eyes study study study study study

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ve1arn
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ve1arn


Join date : 2010-11-23

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PostSubject: Re: My first project Variac   My first project Variac I_icon_minitimeApril 14th 2011, 4:15 am

Hi Cliff,

Graphic worked that time. Very Happy

I'm no expert here, but I tend to like the idea of the variac before the isolation transformer. I can't even say I have any real technical reason for that opinion either. Laughing

I like the circuit though. I have a used case with a 12 volt power supply and cooling fan in it that would make a great case for a unit like this. Once I take out the power supply that is.

Cheers for now, Bob
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Cliff Jones
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Cliff Jones


Join date : 2010-11-22

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PostSubject: Re: My first project Variac   My first project Variac I_icon_minitimeApril 13th 2011, 11:21 am

Does this one show?????

It won't be quite the same as I will use two meters instead of one thats modified but it a good idea for the modified one with adjustments if you can't get what you need.

I am wondering if I should put the isolation transformer, in front of or after the variac, and possibly switch it in and out,and the same with the dim bulb tester. Any thoughts or suggestions?

heres a good demo of a dim bulb test.
Click here for demo on youtube

same author makes one
.making a dim bulb tester click here

I also found a simple program to make meter faces for free called meterbasic, it can be found at:
>CLICK HERE<

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Last edited by Cliff Jones on April 21st 2011, 6:11 pm; edited 1 time in total
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Cliff Jones
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Join date : 2010-11-22

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PostSubject: Re: My first project Variac   My first project Variac I_icon_minitimeApril 13th 2011, 11:07 am

OK thanks I'll tryand see whut hoppund again Suspect
[You must be registered and logged in to see this image.]

it may be too big so here is the link:
If no picture click here

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Last edited by Cliff Jones on April 13th 2011, 11:13 am; edited 1 time in total (Reason for editing : trying to add image)
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ve1arn
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Join date : 2010-11-23

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PostSubject: Re: My first project Variac   My first project Variac I_icon_minitimeApril 13th 2011, 9:54 am

Sorry Cliff, but I do not see any graphic. Maybe it's just me though.
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Cliff Jones
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Join date : 2010-11-22

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PostSubject: My first project Variac   My first project Variac I_icon_minitimeApril 13th 2011, 12:23 am

I now have two meters to monitor my variac. One is a Simpson 3-1/2" Iron vane 5 amps AC, model 1357.
The other meter is A Jewell 150 VAC 5" rectified.
I will now have to design a wood box to include the variac, meters, AC plug, AC socket, in-line fuse, Power Light, power switch, and maybe include an isolation transformer in-line. I was also thinking of a light-bulb socket to do dim bulb-testing. I've got the basic wiring figured after following this layout, minus the meter designed in the circuit. Here a graphic of the one I plan to use:

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PostSubject: Re: My first project Variac   My first project Variac I_icon_minitime

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