Untitled Document

The Weller 100 & rheostats

The words below come from Cooper Tools - They make the Weller range of soldering irons!

Original Message From: Al Hollister of Cooper Tools

Sent: Friday, January 21, 2000

An external rheostat can be used on Weller 100 watt stick iron but since that iron uses a magnastat temperature control it won't have much influence on the tip temperature as you would see on a constant output iron that is not temperature controlled in any way. A brief description of the difference
in each is:

A constant output iron is always operating with the heater on, with whatever voltage is going to the iron from the wall/bench outlet. If you have an iron that is supposed to have a temperature of about 900° at 120-volts but the power in your area is only at 108 volts the temperature will be lower. If an
iron is rated at 100 watts at 120 volts it will be only 84 watts at 110-volts and 81 watts at 108-volts. As you know in stained glass the artist may wish to reduce the tip temperature. For this type of iron a rheostat is no problem. Also, lowering the voltage while the iron is at idle will extend the tip and heater life, especially with the awful acid fluxes used in stained glass work. However, don*t pay more for a soldering iron rheostat that has tip temperature settings.

Since manufacturer of the rheostat doesn*t know what iron you are using and its rated tip temperature, the input voltage at your work area, the size of the tip, etc. it cannot accurately say what setting gives what temperature.

A magnastat or other mechanically temperature controlled iron controls the tip temperature by basically turning the heater on and off by some sort of electromechanical means. These irons are not affected much by voltage variations. An 800° iron with temperature control will try to stay at 800°
no matter what the voltage. If you use a rheostat to lower the voltage far enough to lower the tip temperature you will end up working the heater hard as it will always be on trying to maintain the 800° fixed temperature. This is not necessarily bad as often soldering iron heater burnout occurs when a
heater is turned on, just like a light bulb usually fails when turned on, due to the voltage surge.

Electronically controlled irons/stations should not be used with rheostats. I have not seen any damaged but electronic controls can be unpredictable at low voltages. Weller electronic stations will function properly and maintain temperature down 100 volts and lower. Some temperature controlled stations on the market start to lose temperature at any lower than specified input voltages. There are two real problems when lowering the input voltage - some may be damaged. I have found that many makes lose control with low voltage and may in fact actually increase their tip temperature for a while, and decrease their temperature at other times, with no pattern.

I hope this helps. As you can see I really recommend that you use a rheostat control only with constant output irons.

Best regards,

Al Hohhister

Original Message From: Al Hollister of Cooper Tools

Sent: Friday, January 21, 2000

An external rheostat can be used on Weller 100 watt stick iron but since that iron uses a magnastat temperature control it won't have much influence on the tip temperature as you would see on a constant output iron that is not temperature controlled in any way. A brief description of the difference
in each is:

A constant output iron is always operating with the heater on, with whatever voltage is going to the iron from the wall/bench outlet. If you have an iron that is supposed to have a temperature of about 900° at 120-volts but the power in your area is only at 108 volts the temperature will be lower. If an
iron is rated at 100 watts at 120 volts it will be only 84 watts at 110-volts and 81 watts at 108-volts. As you know in stained glass the artist may wish to reduce the tip temperature. For this type of iron a rheostat is no problem. Also, lowering the voltage while the iron is at idle will extend the tip and heater life, especially with the awful acid fluxes used in stained glass work. However, don*t pay more for a soldering iron rheostat that has tip temperature settings.

Since manufacturer of the rheostat doesn*t know what iron you are using and its rated tip temperature, the input voltage at your work area, the size of the tip, etc. it cannot accurately say what setting gives what temperature.

A magnastat or other mechanically temperature controlled iron controls the tip temperature by basically turning the heater on and off by some sort of electromechanical means. These irons are not affected much by voltage variations. An 800° iron with temperature control will try to stay at 800°
no matter what the voltage. If you use a rheostat to lower the voltage far enough to lower the tip temperature you will end up working the heater hard as it will always be on trying to maintain the 800° fixed temperature. This is not necessarily bad as often soldering iron heater burnout occurs when a
heater is turned on, just like a light bulb usually fails when turned on, due to the voltage surge.

Electronically controlled irons/stations should not be used with rheostats. I have not seen any damaged but electronic controls can be unpredictable at low voltages. Weller electronic stations will function properly and maintain temperature down 100 volts and lower. Some temperature controlled stations on the market start to lose temperature at any lower than specified input voltages. There are two real problems when lowering the input voltage - some may be damaged. I have found that many makes lose control with low voltage and may in fact actually increase their tip temperature for a while, and decrease their temperature at other times, with no pattern.

I hope this helps. As you can see I really recommend that you use a rheostat control only with constant output irons.

Best regards,

Al Hohhister