SN74Z - Classic Instruments Speed Signal Interface - ALL Classic Instruments - Classic Instruments

Classic Instruments: Speed Signal Interface 

• Converts VSS/ECM speed signals to either 8k or 16k PPM

The SN74Z has the following features when used as a Speedometer interface:

• Input Source Options
  • Three wire pulse signal generator input source
  • Built-in Vehicle Speed Sensor (VSS) input source
  • Most Tremec transmissions
  • Later model 700R4’s         
  • Typically a sine wave signal
    • Two wire pulse signal generator input source
  • Classic Instruments SN96 or SN95
  • Typically a sine wave signal
  • One wire ECM signals input source
  • Typically a 5 volt square wave
• Output
  • The output can be selectable between either 8000 pulse per mile or 16000 pulse per mile
  • Outputs a 12V square wave, 50% duty cycle
  • 8000 pulse per mile cruise control output
• Additional Benefits
  • Three different calibration options
  • Instant: drive 30 MPH and press the calibration button
  • Real-Time: press and the hold the calibration button to match the speedometer reading to the actual vehicle speed
  • Marked Mile: Drive a measured mile to calibrate the speedometer
  • Input signal can range from 2000-200,000 pulses per mile
  • State of the art signal averaging software that ensures smooth pointer operation, even in fluctuating signal conditions.
  • Noise-reducing, filtered power output for powered speedometer signal generators

The SN74Z has the following features when used as a Tachometer interface:

• Input Source Options
  • High Voltage Coil signal input source
  • .5-6 pulses per revolution (1-12 cylinder engine)
  • Typically the negative side of an ignition coil
  • 5-12V Square Wave signal input source
  • .5-6 pulses per revolution (1-12 cylinder engine)
  • 20%-50% duty cycle
  • Typically from an electronic ignition box or computer
  • Inductive Gear tooth sensor input source
  • Typically used in diesel applications where there is not an ignition system
  • The sensor can be mounted to the engine near the flywheel to sense the gear teeth as they rotate by
  • Can be used with 32-510 tooth flywheels, 32-510 pulses per revolution
• Output
  • Signal output
  • 12V square wave, 50% duty cycle
  • 2, 3, or 4 pulses per revolution (4, 6, or 8 cylinder)
  • 3 preset flywheel tooth settings
  • 148 tooth – Chevy Duramax
  • 152 tooth – 5.9L Cummins
  • 155 tooth – 7.3L Ford Powerstroke