eBay USB soldering iron in use

Sometimes I've to do a little bit of soldering.  Usually only a few wires and since at present I have no place to leave an iron set up permanently this requires for me to either unpack my rework station or even just a simple mains powered soldering iron.
Even doing this has resulted in me pushing back soldering jobs as the extra time for setup
 as a ratio against actual build time doesn't feel like time well spent.

Then on eBay UK I came across a listing for USB soldering iron for £3.39

Since my electronics is usually tied to an Arduino or Raspberry Pi project I will have a computer up and running and I thought for less than £4.00 including shipped from Hong Kong it was worth a punt.
Well, it arrived this week and as per the picture it includes the soldering iron with a plastic cover for the top.  A USB to 3.5mm jack for power.  A really small stand made from a folded piece of metal with a bit taken out and just enough solder to know it's working.  Actually I soldered about 30 wires using the solder provided and have a bit left over.  Still you'll need to get some solder.

First impressions were positive.  Packed in a proper retail packaging box and not just a jiffy bag like many cheap things on eBay from Hong Kong.

The iron heated up quickly and has a red LED to let you know it's on.
It was definitely hot enough to melt the solder and do the job I required.
Since the original outing I have used it again to replace some current limiting resistors for 5 LEDs in a project I'm working on.  Again all worked great.

As I've only used it twice I can't speak for the long term reliability but from first impressions it is well worth the £3.39 it cost me.

The only things I would change are:
I would have liked the power to be microUSB and not 3.5mm jack.  I've loads of microUSB cables but this is my only USB-3.5mm cable.  If I lose it I'll have to get a new kit. Probably not a disaster at £3.39 and then I'd have a backup.

The tip on the iron is a needle tip. My personal preference is a bevel tip. The ones where it's like they cut a diagonal slice off a flat tip.
Here is a nice instructable explaining the different tips. My preference is called a C series tip in the guide.   Rarely do really fine work and even then a bevel can still be used quite well for most things.

Saying all this for less than £4.00 it feels nice to use and means I can set up, do the rework and pack away in minutes. Which is ideal when only soldering a few wires at any one time.

UPDATE: after posting this I was sent a link to a great video by bigclivedotcom where he tests, tearsdown  reverse engineers the circuit diagram.  Let's just say his review is way better than mine.
Here's the video.

9th Egham Jam – Show and Tell Competition – Prizes donated by Innovation in Education

The good news keeps in coming

Yesterday another pack of prizes arrived in the post for the next Egham Raspberry Jam Show and Tell Competition.  http://eghamjam9.eventbrite.com to register to attend and if you wish to have a chance of winning the prizes to bring along your Project to Show off.

Two (2) PiTrol kits from Innovation in Education were waiting fro me.
These are great kits as they allow you to build your own game controller with the instructions giving step by step details on how to solder it and then a snake game is also provided that works with the controller directly.

Kit of parts

Finished PiTrol

Nevil Hunt is the lead person at Innovation in Education and I have had the pleasure of meeting him at a few Egham Jams where he has come along with the PiTrol, 7 Segments of Pi and PiDapter (link from PiTrol site)

7 Segments of Pi is another simple idea that really captures the imagination. As the name states it is a large 7 segment display and button that you solder from a kit and then code is provided to play a game  

The PiDaptor allows you to connect 2 PiTrols to the one Raspberry Pi.

Each of these kits is great for learning to solder and with the provided code gives the owner the ability to understand how to read inputs from the GPIO pins and use it to play games.  Who doesn't want to play games on their Raspberry Pi.

In the case of The PiTrol prize once it has been soldered up I'd expect it would be possible to then get the controller to work with the many game emulators out there and possibly with the excellent RetroPi emulation system.

The Prize Pool is getting bigger and I'm still hoping to add a few more before the event.

Soldering up Pro Mini Arduino compatible board bought from eBay

UPDATE: Link to blog post on programming the board using a CP2012 USB serial adaptor http://winkleink.blogspot.co.uk/2014/01/programming-arduino-pro-mini-16mhz-5v.html

I bought 2 Pro Mini Arduino Compatible boards from eBay (UK) at £2.15 each including shipping.

They are effectively functionally the same as an Arduino Uno but designed to be plugged into a breadboard. It came with male headers for both sides to go under the board to plug into the breadboard and a right angle connection for the serial connection at one end. If you look closely there are 2 pins (holes) at the bottom just above the main row for Analogue 4 & 5. Also, the near end has Analogue 6 and 7 as well as what I think are V++ and GND.

I decided that rather than leaving these pins disconnected  would add 3 x 2 pin female headers on the top of the board. So, I bought a bunch of headers from eBay for £1.84. It looks like they have gone up to about £2.64. Still for 10 x 40 male and female headers it’s still cheap.

Add a breadboard and some wires and you have a great prototyping setup.

These are nice little board with some strange design decisions like the 2 x 2 pin headers on the end and the 2 pins for A4 and A5. But by using the female headers it gets around these things. The alternative is to not include A4 and A5 if you don't need all 6 analogue inputs.

Here are some pictures from the build with comments.

Bits that came in the eBay order

Creating 2 pin female headers from 40 pin header

Snap off pins. 3rd will fall out. Clean up the edges to fit

3 x 2 pin female headers inserted in the top

3 x 2 pin headers from the bottom for soldering

3 x 2 pin headers soldered up and
right angle serial header in place for soldering

All soldered up and ready to be used

As a side note I also purchased a Leonardo Pro Micro ATmega32U4 Arduino for £3.30

Raspberry Pi + GPIO + Scratch + Remote Control Car

At the beginning of 2013 I started a Code Club at my local primary school and the kids love making and playing the games.  Due to the way the club is set up in the school there is expected to be a few classes after the official Code Club sessions are completed so I've been trying to come up with some ideas of things I could bring in to the class to show the kids that Scratch can do more than make a cat move around the screen.

Then on my regular trawl of the web I found this fantastic code http://cymplecy.wordpress.com/2012/08/26/scratch-controlling-the-gpio-on-a-raspberrypi/ for controlling the GPIO pins on the Raspberry Pi using Scratch.

With an old cheap remote control car in a drawer I had the makings of a fun project for me that (hopefully) will be of interest to the kids.

 Having read that the Raspberry Pi GPIO pins are not protected, so one silly mistake on my part could cause the death of my Raspberry Pi I dusted off my old electronics knowledge and put together a small transistor based driver circuit for the 4 pins used.

one circuit per pin

I originally wired this up on a protoboard and it worked, except for when it failed. Did I mention the remote control car was cheap. Well, the aerial was just a bit of wire and with all the other wires I added to the circuit there was regular interference that caused the remote to activate the wrong signal making it unreliable. Knowing the circuit was good the logical thing to do was to put the circuit on a proper board. Rather than going all the way to etching my own circuit board I made it up on a stripboard

again, 1 circuit per pin. white blobs under resistors are cuts in the tracks

After a false start (details of things I almost did wrong) I got the 4 circuits soldered up and tested.  Worked first time.

Not the prettiest soldering but after doing near no soldering for over 20 years I was happy with the result.

Now I the circuit soldered up and it worked. With a bit of coding in Scratch I could program the remote control car for a sequence of actions like
Forward 2 second
Left 0.5 seconds.
Reverse Right 2 seconds

As you'd expect from a simple remote control car the was no way to give very accurate instruction. The motor was either on or off, no variable speed or feedback.  Even with these limitations it felt great when I clicked on the code in Scratch and car actually did what I expected it to do.

the vehicle of my success!!!

And finally he is a short video of the car in action.

This is why I love the Raspberry Pi and the fun of hacking.  With a little bit of effort you can have a lot of fun. Now I have a remote control car that I can control with drag and drop commands in Scratch on a £30 computer.

Surrey & Hampshire Hackspace evening 7th February 2013

Last night was the second Surrey & Hampshire Hackspace session I have attended at GamesGalaxy in Farnborugh.  Last time I had planned to solder up my Raspberry Pi interface for a remote control car but got sucked into the excellent Eagle tutorial by Bob, so this week I was determined to get it done.

Ohms Law

Bob and Doug

While I was quietly getting on with stuff Bob for his second tutorial gave an introduction to Ohms Law.

Alan busy soldering

What he's soldering

Alan was soldering up an SMD board. A lot more complex and precise than my efforts. Not sure the circuits purpose but as you can see from the pictures Alan had 2 soldering irons at his disposal.

circuit on proto-board. too many wires

For the remote control project I needed to move the components from a proto-board that due to the number of wires hanging off it causing too much interference and stopping the remote from working reliably.  I wanted to build it on a stripboard to get rid of all the wires and also as a small, simple introduction to using stripboard as this was my first time using stripboard.

When I arrived I realised I had left my computer at home and in it’s case were my notes. Nothing too detailed but not a great start.  I also left my soldering iron at home so a quick trip to Maplin around the corner sorted that out.

figuring out the circuit

So began the task of taking a simple circuit with 4 components and figuring out how to do it on stripboard. It’s amazing how something that makes perfect sense on a proto-board suddenly appears more complex than it needed to be.

After a bit of head scratch I figured out the layout and it only used 5 strips.  one for 0V, one for 3V (from remote) and 3 for the transistor and the 3 resistors.  Hopefully a nice neat circuit. 

I then turned the board over to start placing components and thankfully Doug pointed out that I needed to mirror the circuit compared to put the components in on the strip side.  I expect this saved me a lot of troubleshooting later on.

first one soldered

top side components

I soldered in the first circuit after figuring out the mirrored circuit and where I needed to cut the tracks to make it work.
(sorry for the poor picture quality)

Really happy about getting it done and was then about to solder in the second circuit when Robin popped over so I explained the layout and again noted a mistake. I was missing a location where I could take the output to the remote. If you look at the hand drawn circuit above there is no output at the transistor.  Whoops, another mistake averted.  I had to move the transistor forward one hole to create the point where the remote wire would attach.  If you look at the 1^st solder side picture above and the final one below with the 4 circuits in place you will see the one on the left has moved to the edge with no spare holes left. Lucky I had the space to move it.

Also, on the first one I thought I’d be clever and use the legs of the resistors to do the bridging by just bending over the pins and soldering them. It worked perfectly, but looked a bit of a mess so I decided for the other three I would use jumper wires on the top of the board. That is why there are no jumper wires on the first circuit but the other three all have small jumper wires.

All 4 solder in - see the one on the left has moved...

component side up. 3 on the right have  jumper wires

Here is the final layout for 1 of the circuits as a schematic diagram and also on the strip board. I put the jumper links on the strip side for illustration purposed but you can see for 3 of the 4 circuits above the jumpers are on the top.

white under resistors are cuts in the strip

So, that was it all wired up.  I then added the wires to connect to the remote control and the wires to connect to the GPIO pins on the Raspberry Pi through the Adafruit PiCobbler.

After hooking it all up and attaching a screen and keyboard I loaded GPIOScratch, Opened my test code and it worked.  Sending commands from Scratch on the Raspberry Pi made the car drive.

All the problems I had with interference due to the tangle of wires have been fixed and I now have a reliable circuit that I can possibly bring into the CodeClub I run to show the kids that Scratch is not just for making a cat run around the screen.

In my joy it slipped my mind to photograph the finished circuit all wired up to the remote and the Raspberry Pi. So, for the next post I will do some more pictures, a video and show the Scratch Code.

It was an excellent evening at the Surrey & Hampshire Hackspace and next get together is the 21^st of February. If this type of thing interest you then visit the website and join the mailing list. Or even better come along on the night. For more going on you can follow on Google+.

Roll on the 21st and some more computing and electronics fun.