Parking lot indicating light

One of my friend needed a three color indicator(as shown in the picture) for his underground parking lot management system. However, the original hardware has only two wires(including power) that can be spared for the indicating light. However, I found a similar product which uses a very smart design to achieve this function. The schematic […]

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EU1KY ANTENNA ANALYZER

Introduction EU1KY antenna analyzer is a very cheap 600MHz VNA based on SI5351 clock generator, SA612 double balanced mixer and a STM32F7 discovery board. The original source is here(https://bitbucket.org/kuchura/eu1ky_aa_v3/wiki/Home). KD8CEC’s website(http://www.hamskey.com/2019/02/assembling-faa-450-antenna.html) revealed much more about this analyzer, including detailed instructions on how to assemble it, and several popular modifications. Moreover, the CEC firmware has included […]

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Doppler Sensor with CDM324 24.125GHz Module and STM32f303Disco

Introduction I got some CDM324 24.125GHz doppler module last year, and decided to modify it to detect object speed. Despite its complexity to design, CDM324 module has been made incredibly cheap. It basically comprised of a TX antenna, a RX antenna, resonator as frequency source, some power divider and mixer all in a tiny two-layer […]

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A simple rectanna

Basically a rectifier converts AC power to DC, and a rectanna converts microwave power to DC. It’s like “rectifier” and “antenna” combined, hence the name “rectanna”. I always wanted to have a dipole based rectanna on hand, when I explain circular polarisation to someone. And I have designed a very simple microwave rectifier with RF […]

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