Weller Soldering Iron

[GRAHAM99]

I have measured the current and voltage of the iron.
The voltage was 19v and the current 1.4a which equates to 27w.
The iron should be 24v giving 45w which is 1.9a.
The temperature control was working as you could see the current going to zero and then back up to 1.4a.
It looks as though a 24v power supply is needed although it seemed odd that the temp controll was kicking in.
The iron was still not hot enough to do much.
I am learning from all this!

[Hugh Robjohns]

With the iron in free air, 27W might well be sufficient to overcome the radiated heat.

However, when the iron is in direct contact with components -- especially large, thermally conductive ones -- it probably needs more input power to maintain the tip temperature.

[Martin Walker]

Indeed, your iron could well be like some of us here - working perfectly when doing nothing, but not enough energy to do anything useful when it comes to the crunch

[GRAHAM99]

I know that feeling!
I am still curious to see if I can get it working properly so will look for a correct power supply for it.
Can’t really justify buying a “proper one”.

[ef37a]

I know that feeling!
I am still curious to see if I can get it working properly so will look for a correct power supply for it.
Can’t really justify buying a “proper one”.

Yes the lower 'wattage' might well be the problem and yes, you can use any 24V 50VA transformer. I used a monster 250VA isolation transformer that had several 25V windings to make it up to 110V. I used to run two irons off that with different bits. Also you really do need a #8 bit for general work with a 2mm tip. The very long 'needle' bits wear out PDQ.

Dave.

[GRAHAM99]

Just need to get hold of a suitable transformer!!

[ef37a]

Just need to get hold of a suitable transformer!!

Yes, 12 + 12 V traffs are a very common specification at about 2A but a bit more won't hurt and the transformer will run a bit cooler.

Dave.

[DGL.]

Here's a 24V 50VA Transformer that should be suitable,
https://uk.rs-online.com/web/p/pcb-transformers/7320512
It claims to be of the PCB mounted type but seems to have regular spade terminals
You will need a case for it to go into and some way of getting power in/out.
Personally I would use a "kettle style" connector for input and a 4 pin XLR or 3 pin DIN plug for output, unless anyone has any better ideas.

As for cases, either a standard project box from somewhere like RS/CPC or places like toolstation sell enclosures. A metal toolstation enclosure holds the replacement embedded PSU for my Grans stairlift just fine (noting that you'd want to earth the metal enclosure).

The tip on the soldering iron should also be grounded, I believe via a suitable resistor to mains ground.

[GRAHAM99]

Many thanks for that.
I am going to try rigging up some batteries to the laptop adapter to get enough voltage to make sure the iron gets hot enough before I spend any money on it!!
This is all very interesting!!

[GRAHAM99]

I have found a transformer which was inside CD player.
Is it possible to upload photos on here?

[Kwackman]

Is it possible to upload photos on here?

https://www.soundonsound.com/forum/view ... hp?t=62135

[GRAHAM99]

Can you not just upload a photo from your iPad etc?

[Wonks]

No. No picture hosting on this forum.

[GRAHAM99]

Why not?!

[Drew Stephenson]

Copyright liability, hosting space, probably other reasons too.

[Mike Stranks]

Here y'go... this will show you how to do it... NB. NO sound

https://youtu.be/s7vVDGTOHW0

[Drew Stephenson]

Thought you'd managed to find a video of some making their own Weller power supply there Mike.

[ef37a]

https://uk.rs-online.com/web/p/chassis- ... rs/0504672*

With a suitable enclosure, 30-35 quid all up? You have the pencil which are about £100 and so even if that proves no good you could get a new one which I assure you will work on that transformer thus saving you another £100 or so.

"One has to speculate..."

*N.B. I am assuming you have the necessary knowledge to work on and make safe 'mains side' equipment? If not your transformer options are much more limited.

Dave.

[Mike Stranks]

https://uk.rs-online.com/web/p/chassis- ... rs/0504672

I am assuming you have the necessary knowledge to work on and make safe 'mains side' equipment? If not your transformer options are much more limited.

Dave.

Not so sure on that Dave... Ohm's Law had to be explained earlier in the thread...

[GRAHAM99]

Thanks for all the input on this!!
I have never put anything together involving mains voltage so perhaps it is best left alone.
I will have a think about what to do.

[MarkOne]

I hadn't ever thought about this until a few days ago, I'm looking at building a bench PSU for lab projects and looking through a few YouTubes (Yes, not the best source of advice when it comes to legal/regulatory matters) I noted a couple of comments about making mains powered kit and where you might stand in the event it blew up/burned your house down/killed someone

So I'm thinking, in this world of regulation, health and safety, etc, where does that leave the ardent DIY-er?

If you make something with a donor supply like an ATX supply or a laptop brick and you don't modify that in any way, it comes complete with a CE mark (or a UL mark if you are Leftpondian) and has been certified as fit for purpose. Conversely if you cobble something together with a Toroidal, a rectifier, and a regulator from RS and some strip board, even if you know what you are doing, and sometime later it er... burned down your house, would an insurance company see that as a big get out for not cutting you a cheque for a new one (house that is)

Over the years I've designed and built supplies for all kinds of things, both as a DIY-er and in a professional capacity for my job on everything from HiFi kit to bits for fighter jets. But I'm not sure I'd do that any more without using a certified module to convert the killer-watts to the benign ones that run my logic board

[GRAHAM99]

I don’t give up easily!

[GRAHAM99]

There are laptop adaptors on Amazon for about £17 stating 25v and 2a.
I think this would work and be a safer than cobbling something together?
Does the output voltage have to be ac or dc?

[Hugh Robjohns]

...even if you know what you are doing, and sometime later it er... burned down your house, would an insurance company see that as a big get out for not cutting you a cheque for a new one (house that is)

Insurance companies will try all sorts of crap to avoid doing what they charge you lots of money to do!

But legally I think it comes down to 'competence'. You need to show that you have sufficient competence to do what you did. Obviously an appropriate qualification or professional experience would demonstrate competence. Without a qualification, you'd have to indicate that you are knowledgable in the subject, aware of the dangers, and took appropriate and adequate precautions to mitigate those risks.

So demonstrating that you selected an appropriate size of mains cables, calculated the correct fuse ratings, used appropriate insulation around live connections, mounted components in a safe way, etc etc....