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  • $10ish DIY Variable Temp Soldering Iron Controller

    Here is a little project I did. I scanned the internet for various wattage soldering irons, the less expensive types and looked at their wattage/power rating and temperature. Then I plotted temperature vs. wattage/power. And found temp vs. power to be Temp = 10*power + 300 (in degrees farenheit), or Temp = 10*V^2/R + 300 where R is the resistance of the soldering iron as measured with an ohmmeter. You can also infer the resistance for a soldering iron by the following formula power = v^2/R where v = 110 v and power is the power rating listed on the iron (this is approximate). Anyhow after all that I made out the following chart which can be overlayed onto a dimmer cover plate. I have not tested this but you get the point, these are estimates. Additionally, these irons aren't temp...

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    Here is a little project I did. I scanned the internet for various wattage soldering irons, the less expensive types and looked at their wattage/power rating and temperature. Then I plotted temperature vs. wattage/power. And found temp vs. power to be Temp = 10*power + 300 (in degrees farenheit), or Temp = 10*V^2/R + 300 where R is the resistance of the soldering iron as measured with an ohmmeter. You can also infer the resistance for a soldering iron by the following formula power = v^2/R where v = 110 v and power is the power rating listed on the iron (this is approximate). Anyhow after all that I made out the following chart which can be overlayed onto a dimmer cover plate. I have not tested this but you get the point, these are estimates. Additionally, these irons aren't temperature controlled, I know you have to take into account thermal mass, heating and cooling rates, the mass of the thing you are soldering etc. This is more or a less an estimate of the initial temperature at the tip after the soldering iron has been fully heated and before any solder is melted. There is plenty of room for criticism about the above idea and template, which is not very accurate and certainly not temperature controlled. But I think if you use this to set a maximum temperature, it could be helpful, and is probably more useful to estimate a maximum temperature and then solder an item that has a much lower thermal mass than the iron. Which is a very common situation. Bottom line is, I'll use it to cut my 60 watt or 30 watt iron down to 15 watts, which is safe to solder most common electronic components. See faceplate below:

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  • $10ish DIY Variable Temp Soldering Iron Controller

    Ok I made it, and I did a little experimenting. Bottom line is power is V^2/R where power is power dissipated by iron, voltage is the voltage applied, and R is the resistance of the soldering iron. So I measured the resistance of 3 "30 watt" soldering irons hot and cold and found this:Soldering iron 1, 490 ohms cold, 550 hot, iron 2 500 ohms cold 510 ohms hot, iron 3, 650 ohms cold, 550 hot. Anyhow when averaged, that's 550 cold and 540 hot, and I'll just say 545 ohm average altogether. So bottom line is a "30 watt" soldering iron has about 545 ohms resistance, and doesn't change a lot with heating.That leads to the following chart:P=V^2/R ("30 watt" soldering iron)22 watts for 110 volts15 watts for 90 volts10 watts for 75 volts5 watts for 50 volts1 wat...

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    Ok I made it, and I did a little experimenting. Bottom line is power is V^2/R where power is power dissipated by iron, voltage is the voltage applied, and R is the resistance of the soldering iron. So I measured the resistance of 3 "30 watt" soldering irons hot and cold and found this:Soldering iron 1, 490 ohms cold, 550 hot, iron 2 500 ohms cold 510 ohms hot, iron 3, 650 ohms cold, 550 hot. Anyhow when averaged, that's 550 cold and 540 hot, and I'll just say 545 ohm average altogether. So bottom line is a "30 watt" soldering iron has about 545 ohms resistance, and doesn't change a lot with heating.That leads to the following chart:P=V^2/R ("30 watt" soldering iron)22 watts for 110 volts15 watts for 90 volts10 watts for 75 volts5 watts for 50 volts1 watt for 25 voltsSo although I didn't measure the temperature, this chart should allow yout to label your dial for a 30 watt soldering iron and I attached a picture. Just measure the voltage as you turn the dial an mark those voltages as shown.A 60 watt iron would make more sense actually. In order to make a chart for a 60 watt iron, all that you need to do is measure the resistance of the 60 watt iron cold and hot, make sure they are similar and use those numbers to estimate the resistance.I don't own a 60 watt iron, so if someone does, would you please measure the resistance with and ohm meter cold, then hot. Then I could label this a little better for a 60 watt iron.Great idea, thanks! Here are the pics:

    Ok I made it, and I did a little experimenting. Bottom line is power = V^2/R where power is power dissipated by iron, voltage is the voltage applied, and R is the resistance of the soldering iron. So I measure the resistance of 3 "30 watt" soldering irons hot and cold and found this:Soldering iron 1, 490ohms cold, 550 hot, iron 2 500ohms cold 510ohms hot, iron 3, 650ohms cold, 550 hot. Anyhow when averaged, that's 550 cold, and 540 hot, and I'll say 545 average altogether. So bottom line a "30 watt" soldering iron has about 545 ohms resitance, and doesn't change a lot with heating.That leads to the following chart: P=V^2/R ("30 watt" soldering iron)22 watts for 110 volts15 watts for 90 volts10 watts for 75 volts5 watts for 50 volts1 watt for 25 volts.S...

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    Ok I made it, and I did a little experimenting. Bottom line is power = V^2/R where power is power dissipated by iron, voltage is the voltage applied, and R is the resistance of the soldering iron. So I measure the resistance of 3 "30 watt" soldering irons hot and cold and found this:Soldering iron 1, 490ohms cold, 550 hot, iron 2 500ohms cold 510ohms hot, iron 3, 650ohms cold, 550 hot. Anyhow when averaged, that's 550 cold, and 540 hot, and I'll say 545 average altogether. So bottom line a "30 watt" soldering iron has about 545 ohms resitance, and doesn't change a lot with heating.That leads to the following chart: P=V^2/R ("30 watt" soldering iron)22 watts for 110 volts15 watts for 90 volts10 watts for 75 volts5 watts for 50 volts1 watt for 25 volts.So although I didn't measure the temperature, this chart should allow you to label your dial for a 30 watt soldering iron.A 60 watt iron would make more sense actually. In order to make a chart for a 60 watt soldering iron, all that you need to do is measure the resistance of the 60 watt iron cold and hot, make sure they are similar and use those numbers as an estimate.I don't own a 60 watt iron, so If someone does, would you please measure the resistance with an ohm meter cold, then hot. Just plug it in, let it heat up, pull it out of the socket and measure the resistance across the plug.Great idea, thanks! Here are some pics:

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