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embedded-lab.com writes:
555 timer based AM radio receiver published on Tube Time is one of many entries for the currently running 555 contest. This project uses a 555 timer as AM demodulator plus amplifier to drive the speaker. The radio signal is tuned with an LC tank circuit. The 555 timer is configured as a PWM where a ramp signal is created with a capacitor and a potentiometer. The radio signal picked by the LC circuit is superimposed on the ramp signal which varies the duty cycle of the output PWM wave. The variation in the duty cycle corresponds to the audio signal in the radio waves.
555 Contest Entry: AM radio – [Link]
Traditionally, in a crystal detector radio tuned circuits, a mechanical type variable capacitor is used. For those of you who would like to eliminate this mechanical component, here is a modern version of the classic detector set. This radio, as shown on Figure 1, uses a varactor diode instead of the usual mechanical rotary device. [via]
Crystal Detector Radio Receiver Set - [Link]
This project shows how to build a simple AM radio transmitter based on 555 timer IC. The circuit parts are: the 555 timer IC, a NPN transistor three caps, three resistors and a potentiometer. The circuit is able to generate an amplitude modulation signal at 600Khz and you are able to receive it using a plain AM receiver. The range is about 30-40 feet. [via]
AM radio transmitter using 555 timer – [Link]
How to hand decode a QR code transmitted over HAM radio slow scan TV. [via]
Barcode challenge for radio operators - [Link]
This Crystal Radio is highly selective as to separating stations and tunes in the A.M. band from 570 KHZ up to 1.7 MHZ and the short wave bands up to 2.5 MHZ. It is suggested that crystal earphones be used….. or (preferred) feed the audio output of this tuner into an audio amplifier. A good antenna of at least 50 feet is required along with a good earth ground connection.
High Selectivity Crystal Radio with Short Wave - [Link]
PicCon is a PIC microcontroller based radio controller designed for hidden transmitter hunting. When combined with a radio transmitter, it will produce tone sequences and Morse code messages at user-programmed times. It is completely field programmable via DTMF tones, utilizes EEPROM for all programmed options so they are remembered when power is removed, and is quite compact.
PicCon : Hidden Radio Transmitter Controller – [Link]
Greg Charvot has build this Homebrew Radio Transceiver for the 20 M SSB ham radio band from scratch. It is build using solid state components in low noise design philosophy. It uses a bi-directional signal chain rather than a separate transmitter and receiver. Check schematic and construction photos on the link below. [via]
Homebrew 20 M SSB Radio Transceiver – [Link]
This software radio made by PA3FWM is capable of capturing nine amateur radio bands (VLF, LF, MF, 160m, 80m, 40m, 30m, 20m, 15m) simultaneously. The radio receiver is controlled by a nice web interface that let’s you control which band you would like to listen. Check it out on the link below. [via]
9 band amateur software radio – [Link]
Inspired by Jeff Keyzer, Gary Dion decided to build his own WiFi radio. He constructed it using an Asus WL-520gu wireless router, an old USB audio headset, and a bunch of spare parts from his junk pile. After following Jeff’s directions to get the basic radio working, he added some extra niceties such as an infrared remote! [via]
Nice WiFi radio build - [Link]
mightyohm.com writes:
I have been wanting to build a streaming radio for some time. I frequently work in my garage, where I occasionally use my Macbook to play music through a small amplifier and bookshelf speakers. The problem is that my laptop is not always set up in the garage, and greasy fingers are not a good thing to have around a white laptop, period. I could simply buy an internet radio, but I couldn’t stomach the $150-$300 price tag on most players for such a luxury.
So I decided to build one instead.
Building a Wifi Radio - [Link]
