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I have used a single rectifying diode to lower power of 60W Chinese soldering iron due to overheating.

Though I am pleased with the result, I still plan to have variable power output for heavy soldering.

This is where I got the idea of PWM.

I am thinking of rectifying the mains with a full wave rectifier as I have found that these soldering irons work with DC as well. Then stepping th mains to 9V for the 555 timer in PWM configuration (the circuit I used is the electronoob's one) feed it to an NPN BJT and use the soldering iron in series with the collector. Additionally I plan to use the 13003/5/7 as the BJT (I also plan to use it in a Darlington pair for higher gain.)

Shall I go for it? Is there any problem with this method? Also I am compelled to use only 555 as the PWM source.

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  • \$\begingroup\$ draw the circuit you want to ask about \$\endgroup\$ – user253751 Mar 26 at 13:07
  • \$\begingroup\$ Depends of voltage, the iron is designed for. For high voltage just from power outlet easiest way to use TRIAC based cheap voltage regulator. \$\endgroup\$ – user263983 Mar 26 at 13:17
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    \$\begingroup\$ It should be possible to make this work with those components. Suggest you post your proposed schematic. I would be remiss not to mention that all components will be "hot" in this proposed circuit so everything needs to be properly insulated for safety, including the control pot (ordinary pots often don't have enough insulation to be really safe). As an alternative, consider a cheap triac light dimmer. For 6W, you can get inline dimmers that merely need to be plugged in. \$\endgroup\$ – Spehro Pefhany Mar 26 at 13:21
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    \$\begingroup\$ Using a light dimmer is the easiest way \$\endgroup\$ – upali Mar 26 at 14:54
  • \$\begingroup\$ Alternatively, instead of buying cheap crap and then try to fix it, you could buy a quality iron, then spend the same amount of time as you would fixing the bad one doing actual work. The salary you earned from doing that actual work can then pay for the quality iron and more. \$\endgroup\$ – Lundin Mar 30 at 12:31
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The best solution I think is to use a light dimmer circuit. You can buy it already assembled (look one for 60 W) and it is plug 'n play. What they do is almost a PWM on the AC signal from the grid using a triac.

If you want to build it yourself, it is very simple, though I see no point on building it other than just for fun:

Triac lamp dimmer circuit

Image source: Circuits Today: Diac Applications, Triac Lamp Dimmer Circuit

Where there is the lamp you should put your soldering gun.

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    \$\begingroup\$ On the contrary, I see reasons to specifically not build it yourself. \$\endgroup\$ – Hearth Mar 26 at 15:46

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