EEVblog #1113 - Is a $5 USB Soldering Iron Useful

[EEVblog]

Is a $5 8W USB soldering iron actually useful?

[The Soulman]

Without having watched the video, nope.
I'll watch now... 

[SilverSolder]

LOL!  Now all we need is PWM to drive that FET...  and a temperature sensor bodged on the outside of the iron, redneck style...  voila, the $7 soldering station!

[barbeque]

LOL!  Now all we need is PWM to drive that FET...  and a temperature sensor bodged on the outside of the iron, redneck style...  voila, the $7 soldering station!

Get a USB hub and a $2 USB keyboard vacuum and we've got a $10 desoldering station!

[glarsson]

How do you power on this thing "out in the field" without 50/60Hz "in the air"?

[wooby6]

The official model is ZD-20U,
You can buy spare tips (just search ZD-20U).
There are multiple rehashed versions, but they all used the same tips.
There is also a version used as a hotknife for 3d print cleanup called modifi3d which comes with its own special tips.

Funny enough this is my goto soldering iron for any small projects, it's especially useful for manual soldering SMD
also with a simple modification you can make it always on

[woox2k]

I wonder if it's even possible to design a reasonable quality USB soldering iron in the first place. (5v limited to 2A without that quickcharge rubbish) Like with 2A you only get max 10w out of it. Since soldering irons are mostly not working at full load, would adding a supercap or something into it help things along when the tip needs quick boost of energy and recharge it with excess energy when the tip is up to temperature? Would it even be beneficial and has anyone tried it? Proper USB soldering irons would certainly have place in the world considering that 5V2A power banks are everywhere these days.

[thm_w]

I wonder if it's even possible to design a reasonable quality USB soldering iron in the first place. (5v limited to 2A without that quickcharge rubbish) Like with 2A you only get max 10w out of it. Since soldering irons are mostly not working at full load, would adding a supercap or something into it help things along when the tip needs quick boost of energy and recharge it with excess energy when the tip is up to temperature? Would it even be beneficial and has anyone tried it? Proper USB soldering irons would certainly have place in the world considering that 5V2A power banks are everywhere these days.

Supercap probably wouldn't hold enough energy for the cost, but li-ion would work quite well. An 18650 could give you 40W continuously for ~10mins.

[Fungus]

Without having watched the video, nope.
I'll watch now... 

You lose. 

[Fungus]

The touch sensor might work better if it was plugged into something bigger, like a laptop.

But then you probably wouldn't have enough amps to heat it up. 

The touch sensor is the only big fail here, it should be a push button.

[Fungus]

How do you power on this thing "out in the field" without 50/60Hz "in the air"?

Capacitive sensing doesn't need anything in the air.

I wonder if it's even possible to design a reasonable quality USB soldering iron in the first place.

Is it even desirable, given the wide availability of 18650 batteries?

But yes:
a) You could use thick wire in the USB cables to get a full 5V (I'm disappointed Dave didn't measure the voltage inside the iron...)

b) You can connect to multiple USB ports to get a lot more current.

c) A decent capacitor inside could help a lot with the temperature drops, allow you to work at a lower temperature.

There's a lot of possible tweaks to the concept.

[glarsson]

Capacitive sensing doesn't need anything in the air.

But it is not sensing capacitance. It's just connected directly to the 555.

[bullet308]

Looks like it might be worth $3 for smaller SMD work...I Can certainly afford to find out I am wrong...

[tsman]

Careful with how you power it though. The tip isn't isolated from the input so a battery pack is probably best.

[Fungus]

Looks like it might be worth $3 for smaller SMD work...I Can certainly afford to find out I am wrong...

At 450 degrees?

[Brumby]

... to 500º or more.

Yes.  Just hold the tip 2 - 3mm away from the solder paste to reflow.  No contact necessary.

[hli]

You can turn them into SMD desoldering tweezers:
https://hackaday.com/2016/12/07/turn-cheap-usb-soldering-irons-in-to-tweezers/
https://www.youmagine.com/designs/desoldering-tweezers-from-two-usb-soldering-irons

[Barkuti]

This is just to say that, while looking for replacement tips for this USB soldering iron I once bought, I stumbled into this new Aneng LT002 dubbed version of the USB powered iron:




Crazy cheap too: https://www.aliexpress.com/item/4000650074912.html $4.01

If that really works like it is advertised, hats off.

[thm_w]

Looks like USB-C?
8W is only 1.6A, I think they could bump it up to 2.5A ~12W if they wanted to.

[Barkuti]

The Aneng LT002 power input plug is a female USB micro-B, the “charging line” looks to be some cheap no data or bridged data lines USB A to USB micro-B cable.
This newer version seems to be a refinement of the iron which Dave reviewed, thus it uses the same tips with integrated heating element (tips which can be bought for less than $2 a pop in AliExpress, shipping included).
It will be interesting to see how does it manages to adjust the tip's temperature once some technically inclined fellow dissects it and takes a look. Maybe they managed to fit and use some thermistor inside close to the tip?
5 V and 1.6 A means the resistive element is 3.125 Ω. To crank up the tip's power some extra voltage is all it is required (P = V² / R), exactly 6.25 V to reach 12.5 W. But the practicity of this will depend on the way the iron adjusts the tip's temperature, and its resistance to oxidation. The tip reachs quite high temperature in the first version of this iron.

[oPossum]

It is just PWM. AO3400 MOSFET and mystery microcontroller. ~850/950/1050 mA.

[jamesraykenney]

Hate to necro a thread, but there is a newer version of this device that I bought about 7 months ago for ~$11.00usd(from Amazon to avoid the long shipping time, thus explaining the doubling of price).
It is a very nice iron for the price.
The looks are MUCH improved, though not having handled the old version, I cannot say if the ergonomics are worse or not.
It puts out an amazing amount of heat for the power it uses.
It has three temperature ranges, and seems to use the same tips.
Amazon link:
https://www.amazon.com/HANDSKIT-Soldering-Electronics-Adjustable-Temperature/dp/B08FY3CY69/ref=sr_1_3?dchild=1&keywords=handskit+soldering&qid=1622255016&s=hi&sr=1-3

YouTube review(not by me):

[wilfred]

The review said it turns itself off after 10 minutes. I notice with the older one it would turn itself off if you stopped moving it. Whilst I find that a bit irritating it does conserve power if you run it from a power-bank as I do. The ergonomics of the older one are OK, I have no complaints. It does heat up quickly so finding it has powered off is not such a problem.

I seem to recall I got mine for about A$9 from Rockby Electronics in Australia. They cost more on Ebay than the local store.