KNOCK SENSOR and DISPLAY
Here we go, we are going to build some KNOCK SENSORS for our GMCs'.!!!!
The Knock Sensor is a Piezo Electric device that when you stress it, a
voltage is produced. This is similar to the
electronic lighters for the Gas Refrigerators or the lighter for your BBQ
except these sensors do not spark.
(picture)
The sensor shown is for a Ford but I think all of the single wire
sensors are the same. I say this, because
someone told me there are two wire sensors. I wonder if they were confused
with the oxygen sensors? Anyway, this
sensor is screwed into one of the heads , mine will be at the rear , and
when a pre-ignition happens ( a Knock or ping ), a
shock wave is sent throughout the engine and the piezo device puts out a
signal (damped sine wave for your techies).
This signal is about plus and minus 2 volts and the duration depends upon
what is causing the knock. The signal is
about 5 thousands of a second. To light an indicator we have to stretch
this pulse to something much longer. The
article:
http://www.gnttype.org/techarea/projects/projectspage.html
shows a circuit that will stretch this signal and light a light for each
knock and will also send an audio indication if you
can stand the noise.
I am now off to build the circuit, and I will let you know the results. It
looks to me like you could attach this to your
automated distributor and see when it was doing it's thing of retarding the
spark.
Stay tuned. The picture is on the web page
gene
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
Here we go, we are going to build some KNOCK SENSORS for our GMCs'.!!!!
The Knock Sensor is a Piezo Electric device that when you stress it, a
voltage is produced. This is similar to the
electronic lighters for the Gas Refrigerators or the lighter for your BBQ
except these sensors do not spark.
(picture)
The sensor shown is for a Ford but I think all of the single wire
sensors are the same. I say this, because
someone told me there are two wire sensors. I wonder if they were confused
with the oxygen sensors? Anyway, this
sensor is screwed into one of the heads , mine will be at the rear , and
when a pre-ignition happens ( a Knock or ping ), a
shock wave is sent throughout the engine and the piezo device puts out a
signal (damped sine wave for your techies).
This signal is about plus and minus 2 volts and the duration depends upon
what is causing the knock. The signal is
about 5 thousands of a second. To light an indicator we have to stretch
this pulse to something much longer. The
article:
http://www.gnttype.org/techarea/projects/projectspage.html
shows a circuit that will stretch this signal and light a light for each
knock and will also send an audio indication if you
can stand the noise.
I am now off to build the circuit, and I will let you know the results. It
looks to me like you could attach this to your
automated distributor and see when it was doing it's thing of retarding the
spark.
Stay tuned. The picture is on the web page
gene
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
