I have a cheapo Weller 40W unregulated soldering iron. $20 at the local everything store. I've gone through quite a few soldering irons/tips in my life, this is just the latest one. I'm fairly certain I know why my tips get chowdered after just a little while of use: it gets too hot. There's nothing I can really do about that, seeing as it's unregulated…or is there?
I'm wondering, is there anything I can make that will at least give me some control over the temperature of the tip? I'm using regular .032 diameter, 60% tin/40% lead solder. It seems obvious, but would simple voltage regulation (perhaps from a variac) work to lower the total power? It seems fairly obvious to me that if 120VAC is giving me a 40W output, then, say, 60VAC should give me half of that, but it's rarely that straightforward. Given that it's a cheap piece of crap, the idea of monitoring the temperature seems a little out there, but a calculation on input voltage/current vs output power should get me somewhere, right?
Now, I'm asking this question as a (for now) hypothetical "what if". I don't have a variac, or any way to test my theories, I'd just like to know if something like this is possible.
Best Answer
The solution is to use a Triac dimmer set to about 60% -80% after fast warmup.
Then increase for heavy soldering on ground planes, , heavy wires etc.
Tin and clean tip daily with damp sponge after use.
In Japan operators would measure tip temperature daily before work.