EECBlog #17 - Project doesn't work

[justinc]

A few days ago I was going through your older EEVBlogs and came across #17 and how prophetic it was for the project I was working on.

Now about 25 years ago (give or take a few years) I bought a Silicon Chip magazine with a project for a Brake Light Flasher. (For those interested April 1989 Auxiliary Brake Light Flasher.) At the time I did not have a car, but was interested in electronics, and though that this was a most excellent idea.

A couple of years ago I had a near miss with some one just about going into the back of me which dredged up the memory of this project. I contacted Silicon Chip but they wanted $30 for a photocopy of the article. Too much for the Scrooge in me!

I scoured the Internet looking for a similar kit or circuit or unit that would do the basic flash x times, the constant, and not flash again if brakes applied within 15 seconds. With the cost of freight to get things to New Zealand I was really after a circuit that I could then build a unit from. There were a few based around 555 timer ICs

A few weeks ago I discovered the Arduino (which incidentally let me to discovering EEVBlog) which has set me off on another project, my thoughts turned again to a High Stop Flasher unit. I realised the Arduino would be an overkill but I had a look anyway. And blow me down if a Google search took me to the best solution I personally have seen yet at http://180sx.locost7.info/led_brake.php.

I toddled off to Jaycar and bought all the parts I needed, and some tools I was going to need. The old plug in soldering iron was not going to cut it any more!!!

I assembled the circuit on a bread board and after working out the correct MOSFET and transistor alignment/connections had it working brilliantly. I then transferred it onto a small experimenters board.

After a slow and methodical transferring of components and making the links I eventually soldered the last link into place thinking "yippee all finished". I applied the 12V supply and ............... nothing!!! Zip!!! Nada!!!

Immediately the phrase "... I hope you switch it on and it does absolutely nothing..." rang in my head. Thanks Dave!!!!

After 5  min of rechecking the solder joints and following the circuit diagram I realised I have transposed the connections to the PICAXE08M chip. And I know why this happened too. I changed the orientation of the chip from the breadboard to the circuit board and had not adjusted the links to compensate.

Its all installed now and giving those following behind me in the car something unusual and attention grabbing to look at.

So I'd have to agree with you whole heartily in your sentiments on debugging projects.

Cheers

Justin