Variable Voltage Control

speedre9

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I know this may be the wrong forum for this but, I didn't know where else to get an answer. Is this a safe
schematic? Want to use it to control power ( how hot it gets ) of s soldering iron. I will be useing a wall socket to provide 120 VAC and then pluging in the soldering iron at the other end. The dimmer has an off switch.

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For a soldering iron, it is perfectly safe to use a light dimmer. They are both resistive loads. If your soldering iron has a grounded plug, make sure that the ground is properly connected and that the neutral side of the iron goes to the neutral side of your wall plug.
 
All of the incandescent dimmers I've seen use a TRIAC internally to adjust how much of the AC cycle is passed thru to the load.
So they don't really vary the voltage, but do control the average power.

As long as you respect these three rules, it should work fine:
1) It is a basic soldering iron with only a simple resistive heating element (ie. NO fancy digital temperature display, NOT CPU controlled, etc.)
2) Be sure the wattage rating of the dimmer is higher than the wattage of the soldering iron.
3) Be sure to insulate all connections, or better put it all in a box so everything is enclosed.

-brino

EDIT: fixed my mistake; changed SCR to TRIAC above.
 
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Did that for years for stained glass work and it works well.
 
O.K. Thanks guys I knew I could count on you for the right answers. I will build it up soon. Thanks again, I feel safe about useing it now.
 
what Brino said- it would not work well for a Weller-type solder station with the temp switch in the handle, but for a plain resistive iron it's fine.
Mark S.
 
It is for a standard 30w iron, nothing fancy just the iron.
 
I did it years ago using an old jig saw that ran to fast for cutting something or another. I was surprised it worked, I expected it to just pop and spit.
 
O.K., So how can I measure the voltage at the end that gets the iron plugged in?. I have only an analog multimeter.
 
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