my soldering iron idler stopped working...

[Bob M.]

Hi all,
My soldering station is on the fritz so my backup is a 35 watt iron and I connect it (in line) to an idler that I built years ago. The idler drops down the wattage (via a diode on a switch) so I don't abuse my soldering tips too quickly when I'm doing other stuff. When I'm ready to solder, the idler returns the wattage to full pretty quickly. But I noticed that my idler is not working normally so I took it apart and, lo and behold, the diode is toast so I have to mount a new diode but can't remember which one I used. I'm thinking probably a 1N4007 but can anyone confirm or improve on this?
Thanks,
Bob M.

[Helmholtz]

What is an idler? Can you post a circuit?

[Dave H]

What is an idler?

I'm guessing it's just a diode in series with a mains powered iron. A shorting switch across the diode returns the iron to full power.

[nickb]

HH it will be a rectifier in series with the iron and a switch to short the diode out.

Bob: You might consider a 60W temperature controlled iron for $20 or so. No fried tips or components yet enough power to solder pot bodies and heavy busbars.

[J M Fahey]

I use an idler myself, an 1N4007 is enough for a soldering iron, I use a 3A 2N5408 so it also handles an 800W hot plate.

Yes; I know, on paper I would need a 4A diode but I count on the 50% duty cycle.

Never burnt a diode.

[Mick Bailey]

I first saw this idea in an electronics magazine in the 70's and built one for myself. I used to for many years with an iron that was prone to burning tips. Nowadays I have a motion sensor in the hand piece and it switches the temperature down after a period of inactivity, then off if it isn't used after another time interval. All programmable, as with most things these days.

[J M Fahey]

I have the ghetto version of that: a Microswitch attached to the soldering iron holder so iron weight opens it so it receives halfwave 50Hz; when lifted to work switch shorts across diode for full power.

hey, it IS intelligent , has a logic gate built in (the switch diode combination) and runs a program.

Real "computer style" binary Logic:ON-OFF

Just donīt remember if I used Basic (hey, it was 1970) or C++ to write it , I made it 50 years ago.

Note: Microswitch here does not mean those silver knob thingies used to phase split guitar pickups, etc. but the proper name for Industrial mechanical sensors; you use many everyday all over the place without knowing it, faithfully worki g inside elevators, door fridges, automatic garage openers, washing machine weight sensors and 1000 more.

Typically VERY sensitive and designed to be mounted to machines, frames, etc. :
:

I use a similar one, with twice as long lever with tip under soldering iron body, feather sensitive:


Notice this seemingly innocent tiny switch , chewing gum sized, switches 16A@250V AC ! A half horsepower electric motor including its brutal starting peak, and will do that thousands of times.

VERY versatile:

[g1]

Old photo-copiers are a great source for those kinds of micro switches, with all kinds of interesting actuators.
And some of them even have lights that say 'jam', perfect for standby switch applications.

[bsco]

I actually have that done with my bench lighting...sometimes I find it too bright so I plug the lights into an outlet and I have two residential style switches connected....one switch turns on all the bench power so that some of the gear will power up as soon as I turn the switch on.....the other switch is used for the lighting and I have a diode connected across that...in one position the bench lights have full power and in the other it is cut in half......sometimes, depending on what I am going, I find that the lighting is too bright.....works great for me.....

[Bob M.]

It's great to see everyone's 'custom' made solutions. I normally use a Weller WTCPT but as it's not doing it's thing right now and the show must go on, I grabbed my backup 35W for the particular job at hand. I guess I could throw alot of money at this problem but I'm pretty much in the habit of building the smaller shop/bench tools I need/use myself, as many techs do. I'll try that 1N5804 diode solution for my idler, thanks. Alot of the cheaper irons coming from China nowadays have a diode already built in (on a switch), or sometimes a pot/rheostat. I went thru my soldering irons the other day (I must have 10~15) and I could probably use a 60 watt one. There's a 60 watt Hakko sold at Home Depot for $14 and change, which I might do.
Thanks for the replies.
Bob M.