Anyone created a knock indicator light?
06-22-2002, 02:35 PM
#17
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The circuit is a monstable one-shot and can be made using a LM555. You might need an inverter to reverse the trigger logic, the LM555 uses a low going pulse to trigger it. The HC14 has six invertors that also have a noise reduction function (Schmitt trigger), connect all unused inputs to ground. The input has very high impedance so it will not load the signal. I always place a resistor in series with the input and a TVS to ground to limit ESD damage. I am guessing the logic level of the signal since it is passed between the boxes is 0-5 volts so the LM555 should also run on 5 volts. If the signal is 0-12v, just use two resistors as a divider to reduce it by 1/3...10K and a 20K would do it.
The time delay is set by a capacitor and a resistor. Just look at the chart in the link below. Danno suggested a 0.1 second pulse (sounds about right) so using a 10uF cap the resistor is 10K using figure 3.
<a href="http://boards.rennlist.com/upload/LM555.jpg" target="_blank">LM555</a>
Parts list. All Parts and PDF data sheets are at
<a href="http://www.digikey.com" target="_blank">Digi Key</a>
LM555==$0.49
74HC14==$0.49
LM7805==$0.48
LED, caps, resistors ==$2.00
The time delay is set by a capacitor and a resistor. Just look at the chart in the link below. Danno suggested a 0.1 second pulse (sounds about right) so using a 10uF cap the resistor is 10K using figure 3.
<a href="http://boards.rennlist.com/upload/LM555.jpg" target="_blank">LM555</a>
Parts list. All Parts and PDF data sheets are at
<a href="http://www.digikey.com" target="_blank">Digi Key</a>
LM555==$0.49
74HC14==$0.49
LM7805==$0.48
LED, caps, resistors ==$2.00
06-24-2002, 11:21 AM
#18
Racer
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Thanks beab951 (and the rest of you guys). That's the detailed information I was looking for. At some point I'll build the circuit and try it out. I realize the KLR output is in question, but hopefully I can make it work. At $2 in parts it won't be a big deal if it doesn't. I intend to install a buzzer as well (I'll drive it with a mini-relay or transistor).
06-27-2002, 05:46 PM
#19
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Jleake, I ran across this a circuit that seems to match what you want to do.
<a href="http://boards.rennlist.com/upload/CIRCUIT.GIF" target="_blank">Knock sensor circuit</a>
<a href="http://boards.rennlist.com/upload/CIRCUIT.GIF" target="_blank">Knock sensor circuit</a>
07-08-2002, 06:15 AM
#21
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Adrial
Am very interested in this, please post here how it all works out and where tou hook it up to the existing wiring.
(I am mechanical, can get help in making circuit boards, know how to solder parts to it, can hook it up but can not design this kind of things.
Will probably ask very elementary questions)
Thanks in advance
TakeCare
Am very interested in this, please post here how it all works out and where tou hook it up to the existing wiring.
(I am mechanical, can get help in making circuit boards, know how to solder parts to it, can hook it up but can not design this kind of things.
Will probably ask very elementary questions)
Thanks in advance
TakeCare
07-08-2002, 02:03 PM
#22
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I have one of my engineers putting it together, but we still do not know what the input signal from the KLR out is. Also, I cannot test it because I have no motor!
07-08-2002, 02:17 PM
#23
Nordschleife Master
Maybe if I take the knock sensor off and hit it gently, it will trigger the signal? and I'll be able to measure it...
I don't exactly want to crank up the boost until the car knocks...
I don't exactly want to crank up the boost until the car knocks...
07-08-2002, 04:15 PM
#24
Race Director
The test they have you do is with the sensor in the car. Tap lightly on the intake-manifold with the tip of a screwdriver and you should notice the idle dropping a little from the ignition retard. Then all you have to do is put a 'scope on that line from the KLR and see what it puts out.
07-11-2002, 01:19 PM
#27
Nordschleife Master
Nothing yet, but today is a work on the car day...so we'll see if I get to that.
It all depends on how willing the O2 sensor is to leave the hole its been in for 13 years!
It all depends on how willing the O2 sensor is to leave the hole its been in for 13 years!
07-12-2002, 11:52 PM
#30
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If anyone want joins in I am sure I can get a PCB board with parts for a lot less say... $40. The price will be determined by the number of people interested and the size of the board. I will do this at cost since I am in the middle of doing evauations of CAD systems and this would be a "test" design.
On edit:
With the bi-polar responses I am getting on Email I appeared to have jumped into a shark feeding frenzy of people/companies selling products. I will withdraw my offer, I was not selling anything..just looking to break even.
On edit:
With the bi-polar responses I am getting on Email I appeared to have jumped into a shark feeding frenzy of people/companies selling products. I will withdraw my offer, I was not selling anything..just looking to break even.