RAREblog

Sorting resistors is a pain If you've been having fun with electronics for a while you've probably got a box with bits in . I've been playing with electronics for six decades and I have lots of boxes, many of them containing random collections of resistors. Resistors are cheap, but I hate waste, so from time to time I decide to empty some of the boxes and put the resistors away in their proper homes. It ought to be easy, but it's a pain. I was never good at reading colour codes, and the problem has got worse with age. What I want is a simple, quick autoranging ohm-meter that I can use to measure resistor values. So I'm making resistomatic . Resistomatic requirements Most of the resistors I use are 1% or 5% tolerance metal film resistors in the range 220 Ohms to 100K Ohms. Almost all the values  are in the E12 range. (E12 values are multiples of 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2). I'll be happy if resistomatic can achi...

I went along to the Raspberry Pint meetup last night. It's a lively and friendly group, and I'll be going again next month. I'd been asked to do a lightning talk, and gave an update about my Greenhouse monitor project. The background My wife and I have an allotment that's just over half a kilometre from our flat. On it there's a greenouse. At this time of year the greenhouse is full of tender seedlings and my wife likes to protect them from fluctuations in temperature. I've been working on a remote battery-powered monitor which will live in the  greenhouse and transmit temperature data over wireless (not WiFi) to a Raspberry Pi at home. The Pi will log the data and display historic values on a website which we can view from a browser or smartphone. Testing the range I'm currently using a +Wireless Things  XinoRF talking to a Slice of Radio board attached to the Pi. I need to verify that the transmitter is powerful enough to send a signal that t...

Yesterday's Raspberry Jam at Covent Garden was amazing. The Dragon Hall was packed with Raspberry Pi enthusiasts of all ages and the whole event pulsed with energy. I ran the Shrimping It! workshop  with some very welcome help from Jim Darby (@HackerJimbo). I'd never had a group that large, and I'd managed to bring the wrong glasses, so Jim saved the day. By the end of the day we had lots and lots of LEDs blinking under program control, and lots of experimenters who'd discovered how breadboards work and what a capacitor looks like. The organisers did a fantastic job, and made everyone very welcome. I'll certainly be going again. The next Covent Garden Jam will be on 20th June, and I've got the date in my diary.