Monday, May 30, 2005


One of my interests has always been computers and I've always known the basic theory about how computers work, how the electronics operate etc. I know how electronic components work and what each does and even the formulae that are relevant but I've never been confident enough to actually dive in and start creating stuff from scratch.

I enjoy the Velleman kits from Maplins... ten minutes with a soldering iron and you have an electronic game or quiz buzzer or clock, but I could never follow how they worked properly. There was always some strange arrangement of components that confused me.

Recently, I was asked by my brother to make a little "disarming" pack for his Scout group for a camp they are going on. I made him one a few years ago that was basically a small circuit with no electronic components that the Scouts had to "disarm" without setting it off. It consisted of a buzzer and a battery. The buzzer was constantly short-circuited by a small resistor on a wire that stopped it sounding. When the wire was cut or the resistor removed, the short circuit disappeared and the buzzer sounded.

That was crude and simple and didn't really work very well apparently, and I was also concerned about how safe it was so had to test it a lot. A few weeks ago, my brother announced that he wants another one and I had enough warning this time to do it properly.

I found the Kelsey Park Electronics Club website, belonging to a school many miles from myself, and it's been a lifesaver, explaining things that I've never seen explained anywhere else, in a simple way, with lovely printable PDF's for the projecta. The author clearly knows his subject and it is a fantastic resource.

Using that website, analysing a few of the circuits and stealing a few of the ideas from there I've come up with a brilliant circuit for this year's camp and have already spent a small fortune at Maplin's buying the breadboards and components and testing it out. Now, if only I could find a louder but lower-power buzzer than the one that cost me a tenner!

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