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Choosing soldering iron

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throbscottle

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I took my soldering iron apart to see how I can modify to fit a thermocouple to connect a pid controller. Well, with not much poking and prodding one connecting wire came out of the element and it's binding wire started breaking into pretty little semicircles - so I don't have a soldering iron anymore.

I did eventually work out I can replace a grub screw with a modified one, with the thermocouple inside it.

The thermocouple wire has to go through the handle, but can run outside the barrel.

Please don't anyone suggest I get ready made station, even the cheapest are not affordable.

I'm looking at 40/50/60w irons now

In the meantime, I can't afford the likes of Weller or Antex, so I'm looking at cheap mains soldering irons on eBay. The ones like to my old one are very cheap, starting about £1, but the old one was pretty reliable. But I also found some WLXY irons - does anyone have experience with these? It comes with a 2 core lead - is it easy to get into the handle to fit 3 core?

Also I am looking at this one: **broken link removed**
no brand is given - note the nut that holds the tip on. Does anyone have experience with one of these, or this style at least? How easy would it be modify?

Also, the black and red Duratool irons look nice - does anyone have experience with these? Again, how modifiable are they?

There are some quite nice looking Hakko clones (well, I presume they're clones) which have a temperature adjuster in the handle. I'm guessing this doesn't have any kind of feedback, but again, they look like nice irons, and I'm wondering if they are similar enough to the Hakko soldering station irons I can put a thermocouple in the same way.

Well, anyway, thoughts and comments welcome as always :)

TIA
 
Okay so I'm leaning towards the Hakko clones for low voltage stations. The connector on them looks like a mic connector - can anyone confirm if it is? Also, does anyone know what sort of temperature sensor they contain? My pir controller can do K type thermocouples or rtd's...

If I don't get one of those I might get one of the 48W ones - looks like it has a 5 pin din plug - at least I have socket for that! Think they do have K type tc.

I will just have to rig up 1 or 2 atx psu's to power it for the time being...
 
i could be wrong but i think MR DEB got a hako clone and put a sensor on it, do a search i am sure there is a thread in the micro section somewhere. the one you linked too on ebay looks like it has the same kind of changeable bits that my soldering station has, also at that price if you can rig a PID controller to it and get a bit set (if they fit) for about £10 (i think there is ten bits) then you should have a pretty good iron, and alot cheaper than i paid for a rework station! ive no idea what sensor type the HAKO are but a good google should tell something as they seem pretty popular to mess about with, try and find the mr deb thread from memory i think that should give you a better idea of the iron or send him a pm

cheers jason


edit

here you go i think i found it https://www.electro-tech-online.com/threads/pic-controlled-soldering-iron.125981/


looks like RTD
 
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Reading it a bit more it looks like the Hakko irons have an rtd inside. Starting to look like they have standard din plug too. I'll stop answering my own post now...
 
ghostman11 - thanks for that - interesting. I've found a few similar projects on the web now...
 
Just been looking at transformers - it's all very well jury rigging atx psu's, but at some point I'll want something more permanent. Damn they're expensive, unless you want 12v, in which case they become very cheap! I might put a couple of lighting transformers with secondarys series - cost 99p each.
 
if i get a chance over the weekend i will look inside my soldering station and see how its done, mine has a hakko type iron i think and a smd hot air gun, but like you say the exspensive bit isthe transformer
 
I was reading about the lighting transformers - apparently they output ac but at several KHz, so putting the secondaries directly in series is out of the question. But I did have a Brainwave - which I'll be testing in LTSpice shortly.

Rectify & smooth the secondaries, connect them in series, stick a mosfet (I have a few pulled from old monitors) in series with each pole, drive them using a small low voltage mains transformer with ct to 0v, connect the outputs together - hopefully I should get something resembling 24vrms following the mains waveform...

Okay just been trying simulating that. Not good, don't know why.

After reading the datasheet for the Hakko irons, it looks like I can't use one with my pid controller anyway. The rtd in the Hakko irons should be 43 to 58 ohms at room temperature, and the pid controller only works with a thermocouple or pt100 rtd, which according to wikipedia is 100 ohms at 0°C - so that's out.

So it's back to modifying a cheapo iron or getting a Solomon style iron - which do have a thermocouple inside.
 
The rtd in the Hakko irons should be 43 to 58 ohms at room temperature, and the pid controller only works with a thermocouple or pt100 rtd, which according to wikipedia is 100 ohms at 0°C - so that's out.

.
i could well be wrong but check what the HAKKO is at zero degrees ;) or check what the pt100rtd is at room temp :D i would be surprised if there was much if any difference afteral your not compareing like for like temp wise, i have no idea on theese temp sensors but i would have been more concerned if the HAKKO was 100 ohm at room temp,.

just a thought........
 
Mmmm, I think you read me backwards - I don't have a spec for the Hakko irons at zero degrees or for pt100's at room temp! But I do know these rtd's are ptc, and have come across a table showing resistance of the Hakko sensors at operating temp - it is around 100R give or take depending on temp. Definitely not compatible with my controller (which is a RKC REX-C100-K02-M*AN, though it may not be real RKC, I just got the cheapest one I could find (middle of last year), hadn't even heard of RKC at the time. It was cheaper than rolling my own.)

Oh look, here we go: https://www.auelectronics.com/forum/index.php/topic,208.msg512.html#msg512 - Hakko rtd slope
https://www.electro-tech-online.com/custompdfs/2013/03/imnzc21e1.pdf - pid controller

Interestingly, some Hakko irons don't have a temperature sensor - the station alternately provides power to the element and measures it's resistance.

So far resisting getting one of the ones floating around on eBay with a temperature control in the handle. It would be easy but a bit heartbreaking :/
 
Needs proper biasing, but this is the sort of thing I had in mind with the 2 lighting transformers (or any other pair of 12vdc supplies). Very simplistic I know. I missed off current limiting resistors from the transistor bases - doh! Works better with emitter followers than with source followers. The AC signal is off a small mains transformer, though it could be derived from one of the lighting transformer secondaries - I read they run at about 38KHz.

R1 is the load - or soldering iron element in this case.
 

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Okay ordered this soldering iron: **broken link removed** - Ill have to replace the mains wire and plug, it can go directly to the pid controller - which will have a nice box to live in :)
and this thermocouple: **broken link removed** - probably have to cut the button off the thermocouple and twist the wires together, but we'll see when they arrive, probably in about a month...

I'll post details when I get put it all together - hoping the end result will be quite nice. It can even have a home made stand on top of the box :)
 
Okay ordered this soldering iron: **broken link removed** - Ill have to replace the mains wire and plug, it can go directly to the pid controller - which will have a nice box to live in :)
and this thermocouple: **broken link removed** - probably have to cut the button off the thermocouple and twist the wires together, but we'll see when they arrive, probably in about a month...

I'll post details when I get put it all together - hoping the end result will be quite nice. It can even have a home made stand on top of the box :)


The iron puzzles me, it says 24V output and 220V input. Where does the 24V come into it? The mains plug is directly onto the iron.

Strange to is the American plug on it, yet 220V, looks like their market was in the east, where they use those plugs on 220V.

At least the iron takes standard bits, a big advantage when you look at the silly price of Antex bits!

It should be here in less than a month, a week to two weeks seems to be the average delivery time now all the holidays are over.


I would be interested to know what your total investment in it will be, including the controller and all the bits to make it up.

Reminds me of my first "controllable" iron, an Antex and light dimmer! Don't think it achieved much though, apart from extending tip life
 
I've been in a similar situation - don't want to spend lots on a branded iron but want something temperature controlled.

I bought a couple of replacement Duratool 24v irons from Maplin which are intended to be used with the soldering station. From the basic testing I've done they have a thermocouple in the head of the iron which gives a proportional voltage to the temperature. They also have the four pin microphone type connector at the end.

If you put in N91FA on the Maplin site you'll see what I mean - they are only a tenner as well so pretty much disposable.

I've not got any further with the project but will probably resurrect it sometime this year.
 
Sorry for the long rant here, I really didn't mean to go on this long!

N91FA - looks like one of the ones I eventually ended up avoiding - having found some irons with the 4 pin mic connector, then found replacement elements for them, the elements looked to only have the heater wires coming out, which would mean the temp is measured by testing the element resistance - which is pretty sensible, if you think about it. Wish I'd known they contain a thermcouple - would have been ideal - but for the extra cost of needing a transformer.

I actually found some quite nice irons with built in adjustable temperature control - according to the forums I've been reading (the SID project on dangerous prototypes has provided some very useful info) these do contain some kind of sensor. But for the fact I already have the pid controller I would have got one. long!

N91FA - looks like one of the ones I eventually ended up avoiding - h

Re the strange combination of 220v irons with US plugs - these are very common on eBay. Some vendors even throw in an adapter for your country. Some of them have an extra wire with a mini croc clip on, for grounding.

I hadn't noticed the 220v 24v out thing - I'm hoping it's a typo - there looks to be a lot of copying and pasting between the listings for different irons. Not to mention widespread use of Engrish (**broken link removed** if you need a giggle in that department). I think I may have actually looked at this iron a few times and avoided it for this reason - obviously frustration got the better of me there.

One reason for picking that iron was the wide range of bits available. As far as I can tell it should be fairly easy to modify as well.

Total cost. I got the pid controller last year off eBay for about £8 - I just kept bidding on them until one finished within my price range. They usually go for about £16 I think (oh, here's one like I got:**broken link removed**). Much cheaper than the parts to build my own. The reason I got this pid controller was because I had a cheap 30W iron I got from Wilkinson for under a fiver years ago - similar to this one: **broken link removed** except with a blue handle. They're very common in diy shops and reasonable for the cost (cheap but not nasty). I was going to modify it slightly and fit the theremocouple which came with my cheapo Mastech multimeter using some kind of little collar I was going to make. The plan was to make a box with the pid controller in it, a thermocouple socket bought off eBay (which never arrived, and I moved house in the meantime, so bye bye 99p) and a standard single mains socket to plug the iron into.

So cost was £8 for the controller, £1.31 for the thermocouple, £4.89 for the iron - so £14.20 in total. Any other needed parts I already have.

But then of course, having settled down after the house move, I thought I'd investigate the iron to see if I could get a thermocouple inside the barrel (yes, it is possible), but the element started to fall apart. So at that point I was stuck with the pid controller which for the required temperature can only work with a K type thermocouple, and no iron. It was only after I started digging on the internet and found other homebrew soldering stations which use irons which already have a sensor in them that I started looking at these. Although I could have used a Solomon style iron I didn't think they look comfortable to use. It was only after about 3 days of looking at soldering irons I decided to get a mains iron and stick with my original plan, although I did opt for getting a different thermocouple, since this one has fork terminals fitted and looks pretty sturdy. I'll have to replace the sensor though - I'll try cutting off the casing, but may end up cutting it off altogether and twisting the wires though unless I can weld them somehow. (In a previous thread on the subject someone mentioned dragging the end along a carbon block to do this).

Well anyway I've gone on far too long with this and I'm going to bed :)
 
Update for anyone who's interested.
The cheapo soldering iron arrived yesterday, so I immediately took it apart to see how I can get a thermocouple in. Took some photo's since I'm documenting the entire project - I'll put the whole lot up somewhere when it's finished.

Looks like there should be room to get the t/c (sans button) up between the sleeve and bit, so that's good. Since it's a screened t/c, the screen can provide the earth connection, so I'll stick with the twin core flex supplied instead of replacing it with 3 core. Might see if I can get some rubber tube to slide over the whole lot. Plan is to drill a hole through the barrel mount, from the handle. Will have to feed it through with the mount screwed into the handle though, which is a pest.

The iron uses a rectifier to halve the supply voltage - this would explain the presence of a US style plug in the photo - it obviously has a 110v element. The iron actually arrived with a very cheap Euro style plug fitted.

It's a good job I took it apart, since it arrived in a potentially dangerous state. Connected to the DC side of the rectifier is a long bare wire, which just reaches the metal cord clamp - meaning the clamp could easily be live. Not good. Some poor soldering inside too. Looks like it's an untrimmed wire from the rectifier.

I actually have an old shaver transformer - doubt if it will handle 40W but if it will I'll use that and take the diode out of the iron.

Everything on the package is in Chinese apart from "220v", a list of features on the back (which says it has a power light, which it doesn't have) and the model number. Nowhere in English does it state the wattage.

Interesting observation - it would be possible to build one of these entirely from spare parts - everything is available.
 
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