Arduino Compass with OLED display for antenna beam heading

 Here is an Arduino based electronic compass with a local OLED display, the magnetometer sensor can be mounted on a radio antenna and can output antenna heading to a PC and a local OLED.

This same circuit could be incorporated into a True bearing compass if mounted in a small case with a 9 volt battery. For purposes of demonstration the photo shows an Arduino nano with digital OLED display and a GY2713 magnitometer ,which is a break out board for the HMC5883L chip set.

The circuit diagram is included along with the Arduino sketch code, which is a combination of Adafrut's OLED and magnetometer libraries as found in the Arduino IDE.

For  source code please follow this link to my google documents shared folder:

Sketch ino

APRS switch makes any Ham radio transceiver act like a APRS tracker

The following circuit uses a Tiny Tracker 2 APRS tracker from Bionics and a standard "Hockey puck" GPS receiver and allows switching between the speaker mic on a handy talkie and the APRS
tracker.

The switch has three positions as following:

Mic: has the transceiver in normal mode with speaker/mic fully functional and the APRS system does not transmit or broadcast GPS location to the APRS system.

APRS : has the transceiver in full APRS mode and GPS locations are broadcast to the APRS system
if any stations are within range. The transceiver  channel needs to be programmed for the APRS
frequency 144.800 Mhz as used in Europe.

Split: The transceiver RX is programmed for any number of your favorite repeater or simplex frequencies however the TX must be programmed for the 2m 144.800 as an output to the APRS system, So this will necessitate the programming extra bank of special split channels in your radio.
In this mode the tracker is running blind, as I live in a very quiet APRS area this is not a problem for me, however in a built up area with many APRS users this may be a problem, here is a circuit diagram 

and a photo for reference. 

Ryde DATV receiver in small Hammond case

Here is  Raspberry Pi4 mounted on a steel plate with a BATC gpio board 

on a plastic channel as supplied by B&Q. The arrangement allows for 

access to the SD card by removing the front panel, and connections to the rear for access to USB

power and HDMI. A gpio extension cable is used for the gpio board.