This simple On Screen Display uses a board intended for use with a drone or quadcopter. The project was devised by Mike Stevens G7GTN and published in issue 12 of CQ-DATV.
Video quality from the finished item is excellent and ideal for use with amateur TV output. You should understand output is monochrome and single page.
Two PCB's are used in the project but only one is permanently installed, the other is used for programming. Unfortunately there are no mounting points on the OSD board so a little fabrication is required if you plan to box it up. I soldered some push pins to the grounds on mine and soldered the other end of the pins to copper clad board. If you want to run from the shack 13.6v supply a tiny regulator board can be added. See picture.
Out of the packing the OSD board is pre-loaded with a font set suitable for aircraft use e.g. an artificial horizon, not useful for amateur TV. Mike has provided a font set which can be downloaded and installed using the Arduino IDE software and a simple to use terminal programme. All instructions and software links are available on the CQ-DATV site so I will just outline my build.
Before you connect up the board there is a small amount of soldering needed. The OSD board has two isolated sections. At one end video output at 12v and at the other digital input at 5v, the 12v input feeds a 5v regulator which we are told is prone to overheating. For this project the two sections are linked and run with a single 5v supply. There are link points on the board so the alterations are a five minute job with the right tools.
Digital input to the board is serial so the second board you'll need to source is an FTDI USB to Serial interface. These are cheap as chips from eBay; mine was less then £3.00 delivered. Most will come with a set of leads. Beware as some Chinese sellers advertise as FTDI and supply an alternative which in my case didn't work.
Pictured is the genuine board which is only required during programming. Mine can be re-attached if I want to make changes.
Prior to boxing up; the parts cost less than £10 and it worked great. I built two of these with different talkback frequencies; a paged unit is planned using several boards in one enclosure.
OSD with no video input. Monitor TV is under a shelf causing some shading at the top.
Links. Working at time of writing. There are other suppliers for the hardware.