Tacho Signal Converter

Description

This is a tachometer signal adaptor/converter module. It is useful when the tacho is calibrated for a different number of cylinders or different type of signal. It uses the existing signal as input, and provides a new fully configurable output signal.

Compatible inputs (existing signal):

• DC square wave, 5v or 12v (eg. ignition coil / hall effect sensor / signal from an ECU or ignition module)
• AC sine wave (eg. inductive type sensor)

Available outputs (new signal):

• DC square wave, 50% duty cycle, configurable to 5v or 12v pull-up resistor.
• 12v square wave with a high voltage inductive spike on the rising edge (the same as an ignition coil, for older tachometers that require the high voltage spike).
• AC coupled output, for tachometers that require an inductive type sensor (AC sine wave signal).

Adjustments:

• Basic Frequency / Speed adjustment is made with a series of 4 switches inside the module.
• Additional +/- 10% frequency adjustment over the basic setting is provided with a trim pot.
• Alternatively, the trim pot can be used to manually set a frequency from roughly 0.1x to 8x the input frequency.
• “Multi-fire filter” option, used when the ignition coil fires multiple times at low RPM (eg. Ford Barra engines).

The module has 7 wire connections (power, ground, 2 types of input, 3 types of output). Only 4 of these wires are used for most installations (however multiple output types can be used if required).

Small case size (80x40x20mm) making it easy to mount.

Printed instructions included – which detail installation and adjustment.

• This will not work with current-triggered tachometers as found on some old vehicles.
• It will work with voltage-triggered tachometers (that only connect to coil negative, not in series with the ignition coil).
• Some older model voltage triggered tachometers may require modification to work – fitment of a smaller value resistor on the input (see fitting instructions).

Fitting Instructions

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