Soldering Iron Indicator Mod

At first glance, [sprite_tm]s weller mod seemed a bit trivial. In reality, it’s like art with analog electronics. He wanted to add an indicator light for the heating element. To pull it off, he built a funky diode capacitor circuit to create a pseudo-regulated DC voltage, then used a zener diode, a potentiometer and a transistor to make a simple voltage switch that activates a transistor driven LED.

11 thoughts on “Soldering Iron Indicator Mod

  1. Neat hack, I can vouch for those old magnetic switches being unreliabe as heck… My old station would kick out every once in an while; I decided to get a new one when it stoped turning the heater off, and pumping the full 50w into the element all of the time, giving the tip a healthy orange glow…

    I picked up EC2002 off ebay for about $30 shipped (it had a loose contact in the connector, the last job for the old station was resoldering the connector).

  2. At least with mine, the base station clicks, which tells me there’s a relay in there. I have a feeling that would be a lot easier to take an on/off signal from.

    But whatever works, and it’s an interesting circuit.


  3. ok now i want one that sends an email to my phone telling me “just turn it _OFF_ and _WALK AWAY_” when i have left it on and walked out the front door. how many tips have i killed by leaving my poor soldering iron on eleven?

  4. opening the base unit can be done by removing the rubber feet and finding four screws. There is no need to pry the case open with a flatblade screw driver. I like the hack simple useful and informative :-) Another coloured LED on my bench blinking on and off impressing visitors :-)

  5. A simplere solution is to simple wind a coil of wire around one of the secondary wires, then connect each end to and LED with a very low forward voltage bias. When current flows through the heater, the coil of wire acts as a current clamp and generates a voltage like a secondary transformer coil, which then lights the LED.


  6. @5: the Weller WTCP series don’t have a relay; it’s the tip that is clicking, as the modder correctly describes.

    @1: You don’t have more than one soldering iron? :-)

    @9: Yes, that is an awesome idea, I may just do that with mine!

    oh, and Will — “a funky diode capacitor circuit to create a pseudo-regulated dc voltage” ?? You mean a half-wave rectifier? :-)

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