Cub Spy-themed Camp: Cubs Build Lie Detectors!
When director, Geoff Hampson (below, right), isn’t hard at work running Kitronik, he normally tries to stay away from doing anything too technical. However this invitation to help at a Cub Camp was one that Geoff could hardly turn down, having grown up in Manchester with a lot of time spent at this certain Scouting group. It wasn’t because of his skills in peeling potatoes or strapping climbing harnesses to Cubs that he was invited to the camp – although that is some of what he got up to – but because of his Electronics experience.


The Cub Leaders had decided to run a spy-themed camp on June 20 – 22 at Bowley Campsite. With that, Geoff was given a design brief to make a simple Electronics gadget with the Cubs. Given that there were 43 Cubs at the camp aged between 8 and 10.5, the project had to be really simple. To fit in with the theme and difficulty level, a lie detector was chosen. This circuit works on the principle that under interrogation, if you are lying you start to sweat and your skin becomes moister. So by measuring the resistance of the skin (or the moisture) of someone’s finger, an LED can be illuminated and this can be done fairly crudely with just 6 parts. Lie detector

Lie detector - position the tip of the finger across the two wires positioned to the right of the Perspex plate (above) when under interrogation

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‘Having trained up a team of leaders to solder on the Saturday night, we were able to assist 10 – 12 Cubs at a time with one adult looking after just two Cubs. In two hours forty, all of the Cubs managed to solder together their lie detector, which was then mounted onto a laser cut Perspex plate that contained the sensing pads. Having finished making the lie detector, we were then able to find out whether the Cubs have had a wash all weekend or changed their clothing!’ - Geoff Hampson

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