Build Your Own Magneto Timer

engine mechanics to internally time magnetos, and then time them to the engine upon installation. Unlike a mere continuity light device, this testing tool will not ...
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Your Own Magneto Timer By George Adams P. 0. Box 1574, San Bruno, Calif.

out like a continuity light will if placed across the magneto spark gap, which it is necessary to do when timing. The circuit will absorb all current from the magneto with no danger of the engine firing while adjustments are being made. Two indicating lights give accuracy in synchronizing the timing of two magnetos, or when one is timed a certain number of degrees before the other. The lights come on upon opening of the magneto points, and a variable pitch buzzing tone gives you audible indications in conjunction with the lights. A timer such as this retails on the market for around $37.95. Parts for this homemade model did not cost the author over $6.00. The illustrations will give a suggestion as to how you might lay out the components in the box chassis. The two transformers used are the "T-92 Output" type. They are made by several manufacturers. To select proper coding, check the numbers stamped on the transformer; disregard six digit numbers, if any. The following transformer numbers were tried and found to be successful (considering inductive reactance and sufficient voltage step-up based on their reactance at the buzzer's vibrating

ERE ARE DETAILS with which you can construct H your own magneto timer, or "buzz-box" as it is often called. Such a device is a valuable shop tool used by engine mechanics to internally time magnetos, and then time them to the engine upon installation. Unlike a mere continuity light device, this testing tool will not burn •

T-l.T-2 L-l.L-2









COMPONENTS Table radio output transformers (5 watt, 2500 ohms/3.2-4 ohms), wired in reverse. NE-51H neon lamps (other l/125th watt lamps such as NE-2, NE-48, or NE-51 can

be used with appropriate mountings). Buzzer 3-6 VDC door buzzer type vibrator (recommend Sears-Roebuck "Dixon" model). Battery 3 to 6 VDC (recommend two type-D flashlight cells wired in series). Buzzer reed must be adjusted to vibrate at this lower voltage. Polarity is of no consequence. Switch Any SPST (single pole, single throw) switch. Miscellaneous Test leads, alligator clips, flexible hookup Hardware wire, rubber grommets, 3 in. x 4 in. x 5 in. aluminum or mild steel box, nuts, bolts, etc.

frequency range); 7495, 7743-1, 7244, 7590-1, 7497, 7712-1, 7510, 7842-1, 7668-1, and 7483-1. As depicted in the

schematic, the low resistance windings are to the left; the high resistance windings are to the right. ®

SWITCH

RETD

L-l

BLACK BATTERY

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RED -oc BUZZER 34

DECEMBER 1968