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 Poor man's temp control 
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Joined: Sat Dec 03, 2016 1:03 am
Posts: 7
Hello all,

I've been teaching myself some soldering. By teaching, i mean making all the mistakes a nub can manage. With some help from some Olymega folks (thanks Jay and Ross!) we've cobbled together a dimmer switch to an outlet for a cheapo weller iron.

Image

Why not get a proper temp-controlled iron? #reasons ;)

Because my electrical engineering skills are meager to say the most, i have some questions about the setup.

The dimmer model is a Lutron Skylark S-600-WH. Both outlets are connected to the dimmer.

When i check the voltage with no load, it's either on or off, when i add a load (the iron), it behaves normally.

The dimmer recommends a 40w minimum load. my iron is only 25 watts. Should i add a lightbulb or some other load to push it up? Or will it "be ok?"

i know this is not a temp-controlled setup, but my iron gets hot enough that the solder beads on the tip. So i think i just need to turn it down enough for whatever i'm working with (mostly just bumbling atm).

Any advice is appreciated, thank you.


Wed Dec 21, 2016 5:25 pm
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Joined: Sun Aug 26, 2012 2:08 pm
Posts: 1041
Location: Lacey, WA USA
A standard light dimmer requires a load, so checking it with a meter and no load will give you nonsensical results.

If it is working OK with just the iron, I'd not worry about it. Are you sure that iron is really only 25W?

I'm working on a design to add temperature control to soldering irons without a temperature sensor.

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Steve Greenfield AE7HD


Thu Dec 22, 2016 10:26 am
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Joined: Sat Dec 03, 2016 1:03 am
Posts: 7
hrm, i'm pretty sure it's 25W

Image

:lol:

under load (only the iron), it drops the voltage from 121 to 102, and at 1.4 amps, that makes sense

yeah, it seems to work fine. the iron gets plenty hot at full power, i guess next is to experiment with controllability.

i've been reading your project logs about the temperature controlled irons. thats pretty sweet, and definitely above my pay grade for the time being. please keep documenting!

you're quite prodigious with the project diaries... i've been reading about converting a pc power supply to a bench supply. i did a super crude adoption of a PS for a project once, but then i needed the computer, so away went that and never revisited it. Yours is so much more sophisticated... when i'm through with the current glut of work, i'd like to look at building something instead of just buying it.

Thanks for the help :D


Sun Dec 25, 2016 5:03 am
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Joined: Sun Aug 26, 2012 2:08 pm
Posts: 1041
Location: Lacey, WA USA
No doubt, that is 25W.

There will be a certain point in the cycle that a standard light dimmer cannot turn on when the voltage is still too low. So you'll never reach 100% power, although you can get very close.

How are you measuring voltage? If it is not a True RMS meter, then it won't be a very accurate number.

We really need to make a PCB for the power supply project. I need to learn how to use KiCAD.

I have a lot of ambition and ideas, but not as much time, money, or energy. Part of what drives me is what others show an interest in.

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Steve Greenfield AE7HD


Sun Dec 25, 2016 10:26 am
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Joined: Sun Aug 26, 2012 2:08 pm
Posts: 1041
Location: Lacey, WA USA
I have decided that those Tenma cheap soldering stations are only good for the holder. The irons themselves are such cheap junk as to be useless. Two have already had the tip retainer just fall out of the iron while in use. They all constantly unscrew themselves.

I mean constantly. In a 10 minute soldering session, I find I have to tighten the ring several times.

I have bought one iron that claims to have built-in temperature control with feedback. I intend to test it, and if I find that it is satisfactory, buy three more and put them in the Tenma bases. So far, I'm not getting my hopes up.

The reason I don't just buy $60 or $70 temperature controlled soldering stations is that I'm trying to find an inexpensive but good iron to suggest to members. I may be chasing a unicorn. So far, all of the sub $15 irons with control built into the pencil are only power control, not temperature controlled. The cheapest I've found is $30 with an LCD digital display from Banggood.

Weller sells a 25W fixed soldering pencil with LED lights for $15 with Prime shipping. I used an iron similar to that for years.
http://amzn.to/2iwsylG

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Steve Greenfield AE7HD


Tue Jan 03, 2017 1:10 pm
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