The making and future improvement of a buzz box magneto timer

[BreeStephany]

I am in the process of improving upon the design of a buzz box magneto timer I made in A&P school by adding a few minor additions to the basic design.

The circuit is more or less a signal generator and amplifier which generates a signal and illuminates an LED in the event of an open circuit and does not when the circuit is closed.

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LM556 IC pinout

LM324 IC pinout

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I am hoping to improve upon the design by adding a potentiometer to control volume of both the speaker and a 3.5mm headphone jack which I would also like to add to circuit.

I am also looking into improving upon the signal generation to make a cleaner, better sounding signal, but that is likely for Buzz Box v3.0.

I am primarily doing a comprehensive thread over at HackaDay, but would love input from folks on GarageJournal if you feel you have any suggestions on how to go about the improvements or if you have suggestions for future improvements.

 

[American Locomotive]

What is this supposed to do?

 

[BreeStephany]

What is this supposed to do?

It is used for determining when a magneto on a reciprocating aviation engine is making contact and discharging a spark to ensure that the magneto is timed to spark at a manufacturer specified amount of degrees before or after top dead center of the combustion cycle for a given piston.

Its designed to buzz at one pitch and light the green LED when the contact between the ground (black wire) and mag 1 (green) are open, to buzz at another pitch and light the red LED when contact between the ground and mag 2 (red) are open, and to buzz at another pitch and illuminate both LEDs when the contact between both all 3 leads are broken.