The AT-30-A tachometer is a rugged instrument with solid-state circuitry for indication of engine RPM. It is equipped with a ring nut for mounting into a standard 3-3/8 in. (86 mm) dash mounting hole. A full 240° sweep of the pointer gives an accurate indication on a large easy to read scale, and the dial can be illuminated for night reading.

This AT Series tachometer indicates engine speed in revolutions per minute (RPM). Models equipped with an hourmeter (ATH Series) also record elapsed engine running time when the engine speed is greater than 100 RPM.

Calibration has also been improved and is now accomplished with a single push button on the back.

Replaces: ATS-30-12 (20700188), ATS-30-24 (20700202), ATS-40 (20700227), ATA-30-12 (20700175), ATA-30-24 (20700198), ATA-40 (20700134).

Features

• Improved quality

• New, easy one-button calibration procedure

• 12 & 24 VDC versions are included in one model number

• Every model will accept all signal sources: alternator, magnetic pickup or ignition

• LED backlight, no bulbs to change

• Easy ring clamp for installation

Since engine speed is determined one of three ways, these instruments are designed to function with Alternator, Magnetic Pickup or Ignition signals from:

1. Magnetically by the pulses obtained from the ring gear of an engine flywheel by means of an electromagnetic sensor (magnetic pickup). The instrument is designed to function with flywheels having anywhere from 50 to 300 teeth;

2. Electrically by the engine-driven alternator, producing pulses with 4, 8, 12, 14 or 16 poles on the rotor (3 - 52 PPR) when it charges the battery. In this instance, the alternator must have a terminal for the tachometer.

3. From the coil or a tachometer output from the ignition system of 2 - 10 cylinder, 4 cycle spark-ignited engines.

The tachometer is for negative ground or isolated electrical systems. If the instrument is connected to reverse polarity, it will not operate until proper connections are made. It is powered by a 12- or 24-volt battery (operating range: 10-32 VDC).

Not intended for use with Capacitive Discharge (CD) ignitions or magnetos, only for inductive, automotive-type ignitions.

The tachometers are powered by a 12- or 24-volt battery and are reverse polarity protected. These units are for negative ground, positive ground or isolated electrical systems. They are specially designed for use on truck, marine, industrial or stationary engines.