This is the page of projects, most of which related to radio receiver and transmitter. In addition to oldie goodie stuff, I will also include up-to-date projects, for instance, Arduino, LoRa / Meshtastic matters.
An Easy-to-build Active Small Loop Antenna for Urban Indoor MW/SW Reception
Motivation I am living in a downtown apartment where an outdoor “large” antenna is impractical. My only feasible location for a fixed antenna is at the balcony. Obviously for SWL-ing at frequency below ~15MHz, only electrically small 1 antennas can be used. Moreover man-made noise is very high in my area, rendering a whip antenna…
A low cost comb generator
A comb generator is a simple but useful piece of equipment. Most comb-generators rely on a Step-recovery-diode (SRD) to create very narrow pulses which are rich in harmonics. Unfortunately SRDs are expensive, hard to find and very fragile. The above circuit and figure show one low-cost design that replace the SRD with a PIN diode.…
From Hobby to Professional 