DIY Knock Sensor Circuit

[Vlade]

Been on my waiting list of "USEFULL" things to post...

Building your own knock sensor circuit...

Basic parts that you will need

390 ohm resistor, 1/2W (2)
piezo buzzer (not required)
any led
bread board
1N914 or 1N9148 diode
390 Ohm resistor, 1/2 Watt, ±5% (5)
15K Ohm resistor, 1/4 Watt, ±5% (5)
100K Ohm resistor, 1/4 Watt, ±5% (5)
1µF tantalum capacitor, ±10%
Disk capacitor, .01µF
Disk capacitor, .1µF (2)
555 timer IC - good idea to het the DIP socket for those incase events
PN2222 NPN transistor

Basically all the circuit does is detect the spike from the knock sensor and delay the output / drag it out, since the spike from the sensor is so fast one need to slow down the output signal in a way that one can read it.

Cicruit



Here is mine complete, i didn't built the led into the circuit since I want to remotely mount it somewhere.



Original link / Free Plug
http://www.gnttype.org/techarea/project ... spage.html

[ChemCool]

And then Vlade, you just connect up with the existing knock sensor wire?
In other words, we can just connect parallel to the existing knock sensor wire?

[Vlade]

Yip well its suppose to I tried mine yesterday but I think I blew the circuit, my transformer isn't so lekka, it stepped up to 26V (and its only suppose to run 12V) The circuit just beeps now for no reason...

So ek dink my trip5 het sy gat gesien

[Gary57]

I tried mine yesterday

Is your car running again??

[Vlade]

no tried it on a bare block, put a knock sensor on the block, earthed the block with -12V and whacked it with a hammer

[Ero_sennin]

no tried it on a bare block, put a knock sensor on the block, earthed the block with -12V and whacked it with a hammer

maybe you whacked it too hard, thats why it's still complaining!

[johansx]

no tried it on a bare block, put a knock sensor on the block, earthed the block with -12V and whacked it with a hammer

maybe you whacked it too hard, thats why it's still complaining!

You must whack the block, not the sensor...