With the ever decreasing number of radio stations available on the MW/AM band it is becoming more difficult to find a radio station to listen too, if you can find any at all in some places. To help other enthusiasts of restoring vintage radios I designed and built a low power AM transmitter. Project on instructables web site where you can find more details here:
You need to cut-n-paste this link for the project home page, Ebay does not allow direct links.
https://www.instructables.com/AM-Radio-Modulator-Short-Range-Transmitter-V2/
Where possible I use NOS components and home-made parts, this is to help the environment by up-cycling.
The PCB used for the project is designed by me and includes a version of the circuit as a printed sheet for your reference.
This version runs from a 9v battery 15+ hours of use depending on conditions it's as high as 30 hours, The battery can't be included due to Royal Mail restrictions on postage! Sorry.
The PCB has been assembled using the circuit provided by the project. It's in use with some of my radios and seems to work well.
You will also have access to the PCB Gerber files, if you want to order your own PCB. And the re-drawn Circuit.
It is crystal controlled, at a frequency of 625khz or 479m. With the arial provided you can transmit to your vintage radios for testing or just listening to your own music (the iPod is NOT included, just to show it working). It works without an earth (it would benefit from one and a longer aerial, see the project details). You get a good quality signal over a distance of around 0-2 metres depending on conditions in the room. It's not a pirate radio! It's designed to be used for testing vintage radios and personal listening. It works best in close proximity to the radio, but does not require a physical connection to the radio.
This is a short video of a board in use. You will probably need to copy and past it (Ebay does not like links)