How would one go about developing their own soldering iron?

[ZeroTasteGuy]

How would one go about developing their own soldering iron, are there any example pcbs you could orient yourself by? should i just basically copy what the pinecil is but use a bigger mosfet?

Me and some friends want to develop and make a soldering "iron" which is just a usbc input and aixun handle output, with the electronics inbetween, so you could use up to 24v at 8a, this would of course require a bigger fet, but other than that, it shouldnt require much reimagining, other than adjusting the pcb layout and some of the code probably...

[ia]

Hello. Not sure if this is the exact answer, but there was a pretty similar discussion relatively recently, so probably you could start here first.

P.S. I'm not a professional hardware electronics engineer, but in my humble opinion 8A is a total overkill. I use Pinecil V2 with a EPR/PPS power brick via PD3.1 240W supported USB-C cable, and 98W (28V * 3.5A, for long tips) and 126W (28V * 4.5A, for short tips) is more than enough, at least with pretty solid thermocontrol & stability provided by Pinecil V2.

[EsaJaatinen]

Hi

This is basically what I did with "ej-sil" . I sort of aimed to minimize the power stage losses (MOSFET) as well as copper losses of the PCB.

You don't necessarily need physically bigger MOSFETs, just pick one with low Rdson (resistance when fully on) and ensure fast swithing. My "ej-sil" project (linked in previous comment) has 4.4mR Rdson, which is already very low. It's possible to get Rdson even lower, but the costs will rise a bit and the benefit is marginal. That MOSFET type was selected because JLCPCB can assemble them and their Rdson is acceptable in addition to the small footprint.

With 8A constant current the DC losses (when the MOSFET is conducting and not switching) are approximately 560mW (there are two MOSFETS), which is somewhat lower than those used in Pinecil at 3.5A. And as the IronOS pulses the output slowly, swiching losses are so low that you don't have to take them into consideration. My design also has a dedicated MOSFET driver and if your USB power supply can handle fast load transients, you can have very fast swithing resulting in very low switching losses also. Or code soft-start and -stop to the pulses to ensure PSU compatibility.

My experience with a TS101 at 100W is very nice compared to 40W and 80W Metcal models I'm using at work professionally. Metcal is about as good as it gets, and if you need more power, you might want to use a gas torch. My experience is that at those power levels, to which the PID control and boost function helps a lot, it's more question of tip size and shape and having good contact to the part you are soldering. And having good thermal bridge, i.e. tin on the tip, so transfer all the power to the part.

The "ej-sil" can easily handle 24V and 8A, so just download the kicad files for that from the link. Please note that I haven't had the time to test the electronics yet so you might run into some issues 😄. But I still suggest checking them out. And should you have questions, please reply to it's own thread (the link above).

Kind regards, ej