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Old 02-11-2007, 04:22 PM   #1
Ziggyrama
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Default Tapping the stock knock sensor, will this work?

Hey guys,
I am entertaining the idea of tapping my stock knock sensor based on this write up:

http://home.netcom.com/~bsundahl/kno...ten/listen.htm

Pretty much, I can tap the sensor wire, put in a capacitor and resistor and run it into some kind of a listening device. This seems straightforward to me except for one part. My stereo has an auxiliary stereo input which I'd love to use for listening to the sensor. Would the whole thing work if I just connected the signal off the sensor to an aux plug which I can than convert to a proper stereo plug and run that into the deck?
I am concerned that the signal will not be enough for me to hear through the deck. Do I have to do some kind of an amplification first?

I searched around and there's lots of old threads with indirect info. If someone has a similar setup running, please send me some info. Any help is much appreciated.
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Old 02-11-2007, 08:04 PM   #2
Gethin
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That circuit is an audio amplifier, you need it to be able to hear it.

I have used it and it works well.

The signal coming from the knock sensor is too weak for you to plug into your line input, and you need that capacitor anyway to isolate any DC from getting into your ecu.
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Old 02-12-2007, 08:54 AM   #3
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Quote:
Originally Posted by Gethin View Post
That circuit is an audio amplifier, you need it to be able to hear it.

I have used it and it works well.

The signal coming from the knock sensor is too weak for you to plug into your line input, and you need that capacitor anyway to isolate any DC from getting into your ecu.
Did you make that circuit yourself or did you buy something similar? I am a complete noob when it comes to circuitry so I don't have the proper skills to build it. If I can get one cheap somewhere, I'd rather do that. Could I just feed the signal to some kind of a preamp to boost the signal?
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Old 02-12-2007, 09:46 AM   #4
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Useless. It DOES give you audio but you can't hear the difference between what is knock and what is just a loud as heck engine. I've tried it, it doesn't do anything but make lots of noise since our knock sensor is broad spectrum and the processing is done in the ECU.
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Old 02-12-2007, 10:16 AM   #5
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Quote:
Originally Posted by cdvma View Post
Useless. It DOES give you audio but you can't hear the difference between what is knock and what is just a loud as heck engine. I've tried it, it doesn't do anything but make lots of noise since our knock sensor is broad spectrum and the processing is done in the ECU.
Interesting. How would a spectrometer help in this case? I would have to record through a laptop instead and do post run analysis looking for knock frequencies. Hard to effectively sync that activity with what is going on in the car (map locations, timing, load, boost, etc). Not exactly what I had in mind. I think I might have to start reading up on other methods. I would like to avoid driving around with headphones as it's illegal. Knocklite or knocklink come to mind now. Crap.
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Old 06-12-2007, 03:06 PM   #6
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I am *still* in the market for a device like the one you mention, Ziggyrama.

I've done the wiring as you pointed at in your first post. With post-analysis using "Gram" or "Cool Edit Pro" it is most definitely better than NOT listening.

I have wanted to make something proper for years now but I lack the electronics skills to design the unit. I even offered $50 to a certain forum to help me out.

All I frickin want is 4KHz - 8KHz from a knock sensor in realtime with volume control and a headphone jack.

Hell, maybe I'll just rip apart a TXS KnockLite and amplify its signal to an audio jack somehow.
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Old 06-12-2007, 05:48 PM   #7
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Here's an interesting post from http://www.enginuity.org/viewtopic.php?p=6921#6921:
Quote:
Hey,

Thought I'd add my 2c...

<Disclaimer>
Used to work for Link as a development engineer, now part own a tuning shop with 4wd dynapack setup in Christchurch, New Zealand.

The Knocklink, while link's biggest selling product, is not that great. It is basically just an engine noise meter without any filtering (oh look, engine noise increases with revs...). Knocklite from turboXS is much better, or the KnockBLOCK from link is better than that - it has a 5v output and amplified headphone output, and most usefully for you guys, the capability to have two knock sensors input.

Knock sensors should be installed on the block, near the factory (or in) locations as possible - there is a reason the factory chose those locations. You could try tapping into the factory knock sensors, in theory it should work because it has relatively high impedance inputs, but your mileage may vary with this.

Decent headphones, combined with the amplification and filtering in the KnockBlock allows you to even hear light knock, and back off before you get the CRACK of heavy knock, which is where you can hear it without headphones.

Cheers

Nick
http://www.linkecu.com/products/Anci...ces/KnockBlock
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Old 06-12-2007, 06:12 PM   #8
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Yes, unfortunately, Link ECU USA is in "la la land" so getting a KnockBlock is almost futile.

http://www.linkecu.com/dealers/dealersusa

* http://www.link-electro-usa.com/ : Tried their Contact Us email address. Bounced.

* Off Road Buggy Supply (O.R.B.S.) looks super sketchy. Would not order from them.

* Vivid Racing ... nuff said. Won't order from them on principle alone, let alone their high prices.

* Brain Storm, aka miata.org : Dead link

* http://www.finelineimports.net/ : Cannot find KnockBlock anywhere on the site

* http://www.flyinmiata.net : Zero search results for KnockLink or KnockBlock

* http://www.fairfieldcountymotorsport.com/ : Zero Link products shown
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Old 06-12-2007, 06:16 PM   #9
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Not only that, tried to order from www.linkecu.com directly.

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Old 06-12-2007, 07:02 PM   #10
Jon [in CT]
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Maybe you should try their forums to see whether anyone anywhere will sell you a KnockBlock.

http://www.linkecu.com/forum/forums
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