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.
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Ohms Law |
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Bob and Doug |
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Alan busy soldering |
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What he's soldering |
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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.
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figuring out the circuit |
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.
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.
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 1st
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.
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All 4 solder in - see the one on the left has moved... |
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component side up. 3 on the right have jumper wires |

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white under resistors are cuts in the strip |
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 21st 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.
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