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Re Voltage Measure

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speedre9

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#1
When I searched how to measure voltage I found a lot of videos all showing the same approach.
The attached image shows what I found, is this the correct way to measure for out going voltage
or do I need a different way to measure ampereage in order to reduce a 30 watt soldering iron to 15 amp's?. NEW DETAILS.jpg
 

jim18655

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#2
You might need a true RMS meter to accurately read the output voltage from the dimmer. Also, some dimmers don't work properly without a load. Do you need variable output or just half (15 watt) output from the iron? If you series a 40 watt 120v incandescent bulb with the iron it will cut the heat in about half.
 
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Bob Korves

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#3
If you series a 120v incandescent bulb with the iron it will cut the heat in half - 60 volt drop on each device.
I am for sure no electrical/electronic genius, but I think the only way that works is if the bulb and the iron have the same wattage rating (which equals the same resistance). Double the resistance for half the current flow...
 

whitmore

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#5
You might need a true RMS meter to accurately read the output voltage from the dimmer..
If you measure AC current INTO the dimmer and iron, it's just as good as measuring voltage between 'em.
Some irons have internal switches, either dimmers or thermal, and that can confuse voltage reading (interrupting
the current, but leaving the voltage untouched).

Instead of measuring input, of course, the iron's tip temperature is the main concern: that will take
a suitable temperature sensor (a thermocouple). A type K thermocouple at 600F (near the normal
temperature for solder iron tip) reads 12 mV, and changes about 1mV in 30 degrees F, assuming
the 'cold' junction is at normal room temperature.
 

cathead

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#6
I use a Variac on my soldering irons. That way you can control the voltage from zero volts to line voltage and have your iron
at any temperature you want. Some Variacs are capable of voltages somewhat higher than line voltage which could overheat
the iron and cause it to get too hot and possibly burn out. Variacs are great in the kitchen too to control Croc Pot temperature.
 

RJSakowski

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#7
When I searched how to measure voltage I found a lot of videos all showing the same approach.
The attached image shows what I found, is this the correct way to measure for out going voltage
or do I need a different way to measure ampereage in order to reduce a 30 watt soldering iron to 15 amp's?.
I think you meant 15 watts. not 15 amps.

If you just want to cut the power to the soldering iron in half, forget the dimmer and just wire a silicon rectifier in series with the iron. This is a technique used with low cost AC travel adapters for running a 120 "high" power resistance appliances on 240 volts.
 

speedre9

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#8
I have decided to forego this project. Thank you for all the help.
 
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