CoilX: Difference between revisions
(added technical information) |
(→Theory of Operation: refined language) |
||
| Line 48: | Line 48: | ||
===Theory of Operation=== | ===Theory of Operation=== | ||
The CoilX module cleans and shapes the noisy 400v ignition flyback signal in the following way: | The CoilX module cleans and shapes the noisy 400v ignition flyback signal in the following way: | ||
* | * The raw ignition signal is passed through a diode to prevent negative voltage transients. | ||
* | * Then the signal is clipped via a Zener diode so voltages ''lower'' than 75v are discarded. This filters out the ringing components of the signal, which is the primary cause of false triggers. | ||
* | * The clipped signal is passed through an optoisolator via current limiting resistors. | ||
* The optoisolator output is further filtered through a single inverting logic gate using a [http://en.wikipedia.org/wiki/Schmitt_trigger schmitt trigger] filter. | * The optoisolator output is further filtered through a single inverting logic gate using a [http://en.wikipedia.org/wiki/Schmitt_trigger schmitt trigger] filter. | ||
* The filtered / conditioned 0-5v signal is fed into the RaceCapture/Pro timer input channel. | * The filtered / conditioned 0-5v signal is fed into the RaceCapture/Pro timer input channel. | ||
Revision as of 16:42, 23 January 2014
Description
CoilX is a sensor module that converts the RPM signal from an ignition coil primary circuit into a clean 5v logic-level square wave that can be safely handled by the RaceCapture/Pro Timer / RPM input or other electronic devices.
The module features an optically isolated circuit with additional filtering, to help prevent false triggers.
The 1" x 0.5" compact board is designed to be assembled with heat shrink and bundled in-line with your wiring harness.
Wiring Information
Sensor Wiring
Connect the coil connection to the (-) connection of the ignition coil. If you have a multiple coil pack system, choose just one coil pack to connect.
- Alternatively, you may be able to tap into the tach signal going to your instrument cluster, but the signal here must be derived from the ignition coil. Newer vehicles (about 2000 and on) may have a low-level signal that may not work with CoilX. Consult your vehicle's documentation or measure the signal with an oscilloscope to verify.
Soldering Wires
Use 22 gauge wire to solder the connections to the CoilX module.
Be sure to clip the soldered wires flush to prevent sharp surfaces.
Slip then module into a length of heat shrink tubing or wrap in electrical tape to insulate the module. You can include this assembly with your wiring harness bundle.
RaceCapture/Pro Connection
- Connect the CoilX 5v connection to the 5v Vref connection of RaceCapture/Pro.
- Connect the CoilX GND connection to the same ground point as RaceCapture/Pro.
- Connect the CoilX output signal to one of the Frequency / Pulse inputs channels.
See the Installation Guide for the full wiring diagram.
RaceCapture/Pro Timer/Pulse Channel Configuration
In the Race Analyzer app, navigate to the pulse input channel configuration page and configure it for your settings.
- select RPM for channel Name
- select a sample rate. 10 to 20Hz is usually value to start with.
- in advanced settings, select Mode = RPM, Timer Options = CLOCK / 128, and pulse per revolution to match the number of cylinders.
- You may need to experiment with this setting to get the correct RPM reading.
PROTIP: With your engine running you can use the channel monitor to view the current live sensor data.
Technical Information
Theory of Operation
The CoilX module cleans and shapes the noisy 400v ignition flyback signal in the following way:
- The raw ignition signal is passed through a diode to prevent negative voltage transients.
- Then the signal is clipped via a Zener diode so voltages lower than 75v are discarded. This filters out the ringing components of the signal, which is the primary cause of false triggers.
- The clipped signal is passed through an optoisolator via current limiting resistors.
- The optoisolator output is further filtered through a single inverting logic gate using a schmitt trigger filter.
- The filtered / conditioned 0-5v signal is fed into the RaceCapture/Pro timer input channel.
