USB soldering iron test and teardown [video] | Hacker News Reader

USB soldering iron test and teardown [video]

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59 pointsmmastrac28 comments

I am obsessed with big clive, mostly with his teardowns of very dangerous and dodgy electronics.

Agreed, so glad he's getting some exposure on HN. His mild mannered explanations are great, and it's heightened by the contrast provided by his name and appearance (which I can only describe as ex-biker). Such a brilliant channel.

Yes, his channel is wonderful. I love his low-key delivery; he's kind of the anti-Dave Jones (eevblog - also excellent).

I feel a strong need to throw Mike of mikeselectricstuff[1] into the mix.

His dayjob involves building awesome bespoke electronics, and his vlog has teardowns of heaps of really unique items.

Clive/Dave/Mike make up the entirety of my YouTube electronics subscriptions.

[1] https://www.youtube.com/user/mikeselectricstuff

Mike is great, but I can't understand a word he's saying half the time.

Since I saw his review of "Fanny Flambeaux" my life has never been quite the same.

https://www.youtube.com/watch?v=mcDgOGC5Lcc

Pleasantly surprising to see it actually works (even if on an isolated power supply for safety)

I don't really understand how there's 120V at the tip when it's plugged into the Apple USB powers supply. Isn't there a gap between the AC and DC electronics?

It's normal for these sorts of power supplies to have a small leakage current. Hopefully someone else will be able to explain the details, but as I understand it it's the result of capacitative coupling across the transformer and filter capacitors.

I can't explain the details, but I was able to measure the current. Interesting that I didn't measure any current from a genuine Apple charger, but enough current to cause a tingle from the cheap import chargers. https://www.youtube.com/watch?v=pjz4I69YoUA

> but enough current to cause a tingle from the cheap import chargers.

You should try using a multimeter!

Um, I did, as shown in the video...

The voltage is mains AC, but the current is measured in microamps. It's still enough charge to cause static discharge.

I have an earlier version without the movement sensor. It does not work too well in far-out places, because there is no AC or radio field to trigger the 555. I mended this by adding another button connected to USB-minus. My hand now closes the circuit and causes negative edge which triggers the 555.

A question that comes often from a bunch of young people is that they ask me about where to start learning about hardware, soldering, leading into networking (TCP/IP, BGP, etc).

I don't really know how to answer their question.

Does anyone know what I should tell them for future reference if these things keep coming up?

As a teen, I always liked to read the Elektor magazine. They had a nice mix of beginner-friendly articles, plus more advanced ones to keep up the motivation.

A good place to start is an Arduino [1], and connect a button, sensors, actuators to play with.

When you want to move more into networking, step up to the Raspberry Pi [2], which runs Linux and also includes digital GPIO pins.

[1] https://www.arduino.cc/

[2] https://www.raspberrypi.org/

Arduino is the de facto starting place for new hobbyists. It's a very low barrier to entry and runs on pretty much anything.

If you want to learn networking at an Internet of Things level, look at the Spark Photon (basically an ARM dev board with a TI CC3000 WiFi module). It's only $19. The documentation is fantastic, hence I would recommend it over say the ESP2866 which is super cheap but a bit more... hacky.

I think they actually switched away from the TI CC3000 module with the Photon because it had some quite severe, unfixable firmware issues.

I find it curious that people besides network engineers want to know what BGP is. Maybe because BGP kind of rolls of the tongue vs something like ITU-T Y.1564

Tron Club[0] is a monthly subscription service that delivers a bag of parts, including battery and breadboard, and a very nicely done booklet that shows twenty odd circuits to build that month. Each circuit page in the booklet shows a real life photo of the completed breadboard next to the schematic diagram for the same circuit, which is amazing for connecting the abstract to the physical. After a year, they promise to have delivered 350+ circuits. Each month's kit has an area on their forum for help if you get stuck. I'm planning to do them with a nephew.

[0] http://tronclub.com/

(Software person here, so excuse my ignorance). If you run one of these via a laptop USB, won't it put a lot of stress (heat) on the power / usb circuitry? The soldering iron end is basically using all that current to generate heat so my assumption is that the current flowing through the circuits will have some sort of heating effect as well. I always assumed USB was for relatively low power appliances.

Let's put it this way: if you attached a light bulb (which can get fairly hot) to USB, would you expect the same problem? What about plugging a soldering iron in the wall plug -- would you expect that to heat the socket (and cable)?

It's not the current that makes it hot, it's how the current flows through it.

EDIT: It's basically about resistance (the things that get hot are the resistors): https://en.wikipedia.org/wiki/Electric_heating

EDIT2: I'm not an electronics person either. Please feel free to correct me if I'm grossly misrepresenting how things work.

And by "fairly hot", you might use as an example the tungsten filament in a Christmas light bulb - which can be 2500 C!

Power (and therefore heat) is current squared times resistance, or equivalently voltage drop times current. A copper wire or PCB trace has very low resistance, and a soldering iron tip or thin tungsten filament has high resistance, so one stays cool while the other gets hot.

Ok, thanks for clearing it up. I had kind of assumed PCB trace would have some resistance due to the relatively small size of it (compared to say a cable on an electric appliance), but I guess the heat is coming from the soldering iron tip and doesn't need to be huge to get it hot.

You can short-circuit the USB-port at will, nothing bad will happen. And BTW the available current is also software programmable. If the data lines are not used and shorted, the source will give full amps (2 Amps maybe more), otherwise it is 0.5 Amps max.

So what does this mean? Do I get one of these or what?!

If he didn't like it you would know it: https://www.youtube.com/watch?v=ASnLL6ebaco

In the end you need to balance the pros and cons and see which comes up on top in your particular use case.

Personally, for my use cases (field repair of RC gear), I might buy one after this review.

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