Posted by Support staff on 23rd Jan 2025
How tachometer filters work. Will it work for my application?
In this post we will describe how a tachometer filter works, and try to answer the question: will it work for your application.
How a tachometer filter works:
A low-pass electronic filter allows signals with a frequency lower than a certain cutoff frequency to pass through and attenuates signals with frequencies higher than the cutoff. This means it effectively filters out high-frequency noise, while allowing the lower-frequency signals to continue through.
Frequency Response: The filter's cutoff frequency is where the signal's power is reduced by half (a -3dB point). Below this frequency, signals pass through with minimal attenuation. Above this frequency, signals are increasingly attenuated, which reduces high-frequency noise.
The result is that high-frequency noise and voltage spikes, often found in tachometer signals, are filtered out, leaving the desired low-frequency signal relatively unaltered.
General Motors used tachometer signal filters on most of there vehicle in the 70s-early 90's.
Will it work for my application:
A tachometer signal filter won't fix issues caused by mismatched or failing components.
Our filters operate within the 1-800Hz range, suitable for GM vehicles from the 70s to early 90s.
If you install an aftermarket ignition system, its tachometer signal output must be within this range (1-800Hz). Your tachometer also needs to operate in this frequency range.
If your system meets these requirements, the filter will work for your application.