DIY Projects

Lie Detector Electronic Kit and Circuit Explanation

Lie Detector Electronic Kit and Circuit Explanation

Lie DetectorWe’ve had a few emails and posts about folks who wanted to build their own lie detector, here’s one (and how it works) – “The circuit diagram of the Lie Detector is shown above. It consists of three transistors (TR1 to TR3), a capacitor (C1), two lights or LEDs (L1 & L2), five resistors (R1 to R5), and a variable resistor (VR1). Suitable transistors to use are BC547, BC548 or BC549, or any other small NPN transistor. The Lie Detector circuit works based on the fact that a person’s skin resistance changes when they sweat (sweating because they’re lying). Dry skin has a resistance of about 1 million ohms, whereas the resistance of moist skin is reduced by a factor of ten or more.Link.

Weird stuff from Government Liquidation

Weird stuff from Government Liquidation

1722 8701 1167Harvey writes “Where US Taxpayer’s have already bought the best equipment (Like $2,000 hammers) and you can pick up it up for a faraction of its original cost. Get electronics and test equipment, pumps and motors, battaries and computer equipment by the pallet! Buy entire pallets of parts at a time and make the impractical dream a reality! NOTE: Read the fine print and watch out for shipping costs!” Link. I’m bookmarking this for the occasional requests we get for surplus or bizarre decommissioned gear.

Making Cigar Box Guitars – a photoset

Making Cigar Box Guitars – a photoset

88412674 C139A2Af11 MExcellent set of photos of the construction of cigar box guitars from Pasque – “I am building guitars out of cigar boxes with my students. Here are some photos of the prototype I built at home (now updated with photos of my students’ guitars). I went begging and got a bunch of wooden fingerjointed cigar boxes. The fee… a photo of my students with their guitars, a fair trade. The project idea came from Make magazine Vol. 4. Link.

HOW TO – JDM2 based PIC Programmer

HOW TO – JDM2 based PIC Programmer

Jdm2Ian writes “This ‘instructable’ covers my new design that programs 8/14/18/28/40 pin PICs. The circuit is based on the JDM2 programmer, with two enhancements: clock and data line filtering; selectable programming voltage. The ZIP archive contains all the project files. Schematic layout for an updated JDM2 PIC Programmer. Includes clock & data filter, Vpp voltage divider for modern PIC microcontrollers (eg USB PIC 18F2455/4455).” Link.