• Getting started with Bluetooth-ing your project

    07/26/2019 at 20:15 0 comments

    Update I wanted to share. I was able to make a simple LED light on and off at the tap of a button on my phone. Not the most ground breaking development, but it though I'd share the information for those looking to start.

    I've been following the tutorials here:

    and using the MIT AppInventor:

    The appInventor is a great introduction to those who are pretty new to app development. The way you upload your apps to your phone is pretty clever too, all you need to the is download the MIT AI2 Companion app and enter a code for your app. It is advised you go through the getting started tutorial first, its quite painless. You will need an andriod phone, sorry iPhone users.

    There is code supplied with the instructions on Martyn Currey's website as well as a file you can upload to your AppInvetor account.

    You'll have to have a close read of Martyn's explanation of the code in appInventor whilst reading the code in the appInventor in order to expand your understanding what bit is doing what.

    Anyway its a good starting point for those looking to get started on bluetooth-ing their project.

    Guess the next step is reading values to the phone...

  • 1 Hour Hack: Internal light for Landy

    11/06/2017 at 23:20 0 comments

    i won't lie: the amount of crap that floating around my landrover is shameful at worse. However, something that was flaoting in my passenger footwell got me thinking...

    Yep its one of those crappy pound-land (dollar-store for you yanks) LED cabinate lights from a previously failed attempt of having some internal lighting by using the sticky pads that are fitted to them. The ride in the Landrover is not that great, even on a smooth road its bumpy as hell! so they just kept falling don off the sunvisors.

    However I have no rear view mirror, no point in fitting one as all I'll see is the scaffolding of the rollcage! There are still the screw holes above the windscreen for a mirror, which are M3 thread.

    I took the back off the light and stuck some batteries in to check it worked first, then remove the woefully inadequate adhesive off the back, refitted the back plate and drilled a 3.5mm hole in the back for an M3 screw. This also marked the inside to drill a larger hole for the head of the bolt to fit into, albeit exposing the circuit board inside.

    Hardware in place, I then fitted it to the mounting screws in the landrover above the windscreen, then applied some insulation tape of the head of the screw as not to accidentally short out the traces on the PCB:

    Then it was just a case of refitting the LED light onto it and testing:

    VIOLA! quick tap and light, also not reliant on vehicles battery power, which is sometimes the case when I'm working on the electrical systems.

    Took less than an hour and all out of junk parts!

  • The Thurlby Complex

    08/13/2017 at 19:42 0 comments

    Gather round folks and I will spin a yarn of confusion.

    So I acquired a Thurlby PL310 PSU (least that's what it said on the front) a while ago. It had an issue where the voltage adjustment at the low end (0-3V) was very jumpy:

    Although useable, I decided after  a while that I should really get round to fixing this. A quick Google relieved a few others who had suffered the same problem with a common fix: Replace the old wire wound coarse adjustment pot with a new, better, carbon track one. And whilst your at it replace the fine adjustment one.

    There was a pretty google hit of somebody who had posted pics of their repair that was on a site which had not been maintained/dues paid, but can't seem to get the same hits from the same search terms anymore...

    I also read that the voltage adjustment pots were not wired as you would typically expect in a linear PSU. They appeared to be part of a feedback network and being used a variable resistors/rheostats  rather than potentiometers changing the set point.

    Simplified schematic

    I've a copy of the service manual here if anyone wants it: SINCLAIR THURLBY PL SERIES POWER SUPPLY

    Now if you look at the Thandar range of PL series power supplies you will find that the pots are wired as pots:

    Also IC7-A is an LM324....which I couldn't find:

    No LM324 here! So massive pitfall there! Turns out the Sinclair branded and Thandar branded PSU, SHARE THE SAME MODEL NUMBER!! But why the flipping hell did Thurlby do this!?!

    "I know! New company structure, New PSU design, Lets name it  EXACTLY the same as the old product!!"

    ...yeh well done chaps...could have at least bloody versioned it!

    Anyway, massive model number flaws aside, this was  a distraction from the task at hand, but I though I should make the uninitiated aware.

    The task at hand was to replace the potentiometers:

    Rummage in the spares box and a 50k pot (coarse) and 1k pot (fine) were acquired.

    After fitting them and giving them a little test, the voltage was stable and the fluctuating output had gone completely.

    It should be noted as well that if you're testing this after fitting new pots, and you are resting the front panel PCB near the AC line switch, you will see the same fault you are trying to cure! Seems the Mains interference is large enough to cause the same issue.