Cheap LCD temperature gauge, another eBay purchase from China for about £3. Designed as a PC case thermometer, but it will be part of the custom heating controller now I have a working timer module.
Tuesday, 4 November 2014
Friday, 31 October 2014
I bought this up-lighter almost 20 years ago in B&Q. Back then it was fitted with a 500 watt halogen lamp, which was an expensive proposition even back then, so the light wasn't used much. I finally got round to modifying it to take a state-of-the-art LED G10 lamp using a recycled lamp fitting. It is just as bright as before and now uses... 4 watts! That's a 125th of the electricity for the same light output. The cable is a bit heavy and I want to make sure the connections are 100 percent safe and secure before bringing the light into the house, but it works.
We had a security alert nearby yesterday (aka 'bomb scare!'), which was kind of coincidental as we had just finished building our own hazardous-working grab robot. The design is from Richard Pawson's 1986 robotics book, but I beefed-up the end effector (that's mad scientist speak for 'grab') to make it more robust and we are looking at mounting a ram device on top for forcing open suspicious packages!!
Sunday, 19 October 2014
This arm is a hybrid derived from several designs taken from two books and a 'classic' Lego Technic website. The books are -
'Make and Program Your Own Robots' by William Clark (1985, ISBN 0-0916-2890-3)
'Robot Projects' by Richard Pawson (1985, ISBN 0-7112-0419-5)
Both feature interfacing to the Sinclair Spectrum, so using an Arduino or Raspberry Pi would be really suitable alternatives. Clarke's book provides a simple microswitch design using paper clips that we have tried out. I want to look at building an alternative motor with PWM control and optical feedback sometime.
Monday, 25 August 2014
Sunday, 20 July 2014
I wanted to try out the Mindstorms NXT2 with raw I2C, but this involved making a homebrew 6-pin connector because Lego use a proprietary type to avoid kids sticking them into your Ethernet wall socket. Some Minicraft cutting and epoxy sticking later and on the second attempt I had a working breakout cable.
The little board cost a couple of pounds on eBay and has an I2C analogue-to-digital converter with a light dependent resistor, thermistor and variable resistor for testing. Programming blocks for Mindstorms are easily downloaded and installed to the Lego software.
The NXT is reading ambient light and displaying an 8-bit value on-screen.
Monday, 26 May 2014
Well, I've started to come out of hibernation at last, due to the indifferent weather and everyone having a bad cold last week. I finally got around to gutting 4 old PCs and taking the carcasses to the dump, cases for recycling really, and then I upgraded the workshop PC to 2gb of RAM and added a second 160 GB hard drive. Not state-of-the-art, but I was able to install Linux Mint 15 so I can browse the web and do Arduino and PIC stuff again. I treated myself to this Fujitsu Android tablet from Lidl of all places and with a 99p stand, a USB keyboard and the 'On-The-Go (OTG)' adaptor I bought for my 'phone I have myself a cheap transformer computer.
Wednesday, 26 March 2014
Wednesday, 1 January 2014
Bored today, so I decided to make up some remote temperature sensors. They're based on 18DS20 1-wire sensors which can be operated over just 2 wires in power parasitic mode where power is taken from the data line and held in a capacitor on the chip to allow it to make the temperature conversion. In this mode the VCC (positive) and GND (negative, ground) pins are wired together and then to ground.
The ends are made from old bits of Biro pens and pieces of heat shrink sleeve. For anyone who tinkers or 'makes' a good supply of heat shrink sleeve is essential and makes for very neat finishes. Good for car wiring too.