igital tachometers might be accurate but they don’t respond like an analog instrument. This new SILICON CHIP tachometer combines the best features of analog and digital instruments: blip the throttle and the LED bargraph rapidly responds to the change in engine revs while the true RPM will be shown on the 4-digit display with up to 1 RPM resolution.

A gear shift light and a rev limiter output are standard features and it can operate with virtually any car or motorcycle (except magneto ignition). Its vast array of optional setting adjustments makes this tachometer a truly versatile instrument. For performance cars and motorcycles, this versatility includes the ability to display engine RPM above 10,000 RPM.

The circular display section of the tachometer has been made as small as is practical and it can be installed within the instrument cluster of your car if there is sufficient space available. Alternatively, it can be housed in a cylindrical case and mounted using a suitable holder on the dashboard, windscreen or instrument cluster. The main electronics part of the tach-ometer needs to be mounted under the dashboard (or within a side cover in a motorcycle).

The LED bargraph is arranged in a 76mm diameter circle that covers a 286° span. Most of the 32 LEDs are green except for the extreme clockwise end which uses five red LEDs to indicate the "red line" RPM. You can increase the "red line" indication to as many as 10 LEDs.

Fig:2: that Silicon Chip LED Tachometer is more complicated than the basic unit and includes both digital and bargraph LED displays.

During calibration, the red line RPM can be selected, as well as the number of red line LEDs. The tachometer then automatically calculates the RPM increments required to light each LED.