The Gretz Aero GA-TB2 is a very small audio tone generator used to make an audio tone annoucement through your headset advising of a user selected warning function. This warning tone can be used to get your attention for one of a variety of events. Examples of uses are: Clock alarm, gear warning, canopy not latched, door not latched, engine monitor function out of tolerance, low oil pressure, low voltage, stall warning, GPS generated warning, or one of many other warning uses.
The Gretz Aero GA-TB2 puts out an audio tone with a closure of contacts in a user installed switch, or an internal switch in a device like a clock or other device. This contact closure switch can be used to supply + voltage to the Tone Board, or the switch can be used to supply a ground source for the Tone Board. It is your choice.
As you can see in the photo, the Warning Tone Generator is very small. It can be mounted to any flat surface with the two supplied screws through the circuit boards mounting holes. To insulate the circuit board from ship ground there are two provided stand offs to be placed between the backside of the circuit board and the conductive structure it is mounted on. Connection of the wires to the circuit board has been simplifed from the earlier design by the use of a terminal block attached to the circuit board.
The GA-TB is designed to work with 12 volt systems. If you want to use this board on a 24 volt aircraft system, it can be done by use of a user supplied and installed heat sink to the voltage regulator on the board. The circuit is also now designed to operate in a greater temperature range (-40 degree C to +125 degree C) than the much earlier design.