Hello,
I'm about to make this solder station for a Weller LR-21 soldering iron. I have some confidence it'll work, however, just in case there's something I've missed I'd appreciate your comments ... Please note that I do need the circuitry to be fully DC so AC voltage are not possible.
It's basically a comparator which compares the voltage across the PTC resistor in the soldering iron with a voltage that is regulated by the "temp-regulator" variable resistor. When the value of the PTC resistor drops relative to the "temp-regulator", Q5's basis is raised which starts current flowing through Q5 and which fully opens Q1 which outputs ~24.5 VDC to the soldering iron.
If you spotted anything in this that doesn't work I'd appreciate your comments....
Best regards,
Jesper
I'm about to make this solder station for a Weller LR-21 soldering iron. I have some confidence it'll work, however, just in case there's something I've missed I'd appreciate your comments ... Please note that I do need the circuitry to be fully DC so AC voltage are not possible.
It's basically a comparator which compares the voltage across the PTC resistor in the soldering iron with a voltage that is regulated by the "temp-regulator" variable resistor. When the value of the PTC resistor drops relative to the "temp-regulator", Q5's basis is raised which starts current flowing through Q5 and which fully opens Q1 which outputs ~24.5 VDC to the soldering iron.
If you spotted anything in this that doesn't work I'd appreciate your comments....
Best regards,
Jesper
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