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Thread: Here's What I Just Made

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Posts: 31-40 of 41
2015-01-07 02:01:19
Looks nice. Would just need a microphone. Input pins are on the left output pins on the right. Power on the bottom. Would be cool to try
2015-01-07 23:39:09
The laptop should have its own amp to handle a mic. Figure out a way to filter the signal. The calculated knock frequency for an sr20 is right around 6.5khz. Using a bandpass filter you can isolate 4khz to 8khz then pass the signal to the laptop and analyze the signal with something like this program. Sonic Visualiser

If you can determine a time constant for a WOT pull against a recording using a spectrum program, you can manually export the data into excel and define x and y respectively as rpm vs amplitude. This should help isolate the cells that need to be adjusted.
Last edited by ebinkerd on 2015-01-08 at 16-25-09.
2015-01-07 23:58:06
True it should accept a microphone on it's own. Since I've down time with the car I'll probably splice the cable so I can take the signal directly from the mic to the laptop
2015-01-08 15:44:22
Ordered the 3.5mm TS connectors last night to splice in and grab the signal straight from the mic
2015-01-20 00:29:47
Put the 3.5mm connectors on so now I can go straight from the mic to the computer for recording. Made a recording but also found a break in the cable right at the battery clip so going to have to change it up I'll probably order some ethernet cable to use instead and see if that works out. Anyway, here is a recording that was made, there is some popping from the broken wire, but basically this is what it sounds like.

I also want to change it so it just uses a piece of copper with a bolt hole to bolt it directly to the engine block.
2015-01-20 02:56:12
I'll be honest, it sounds like a microphone in the engine bay. Any reason you dont use a piezo knock sensor? I mean this is what they are designed for.
2015-01-20 03:11:29
Originally Posted by ebinkerd
I'll be honest, it sounds like a microphone in the engine bay. Any reason you dont use a piezo knock sensor? I mean this is what they are designed for.

Yeah I'm not thrilled with the quality. Going to try changing the configuration of it. Anyway, I haven't tried tapping into the stock knock sensor to analyze that signal, but my Nistune won't log the knock signal so just exploring other options. Ideally I'd like to get an audible solution working, so that it can be much more sensitive than stock knock detection.
2015-01-21 00:38:31
Took the clip off today, turns out it had fallen off the bolt at some point and was just dangling over the heater pipes. I'm sure that played a part in the poor resolution of the audio. Now that I have it off I'm going to drill it out for a bolt hole when I get a chance.
2015-01-28 01:59:13
Finally got around to drilling it out for a bolt. This will fit the stock bolt for the knock sensor, or there are several other locations around the cylinder head this will fit too. Hopefully this will result in a much better audio quality, but we will see. For now the car is out of commission with a bad bearing so this will have to wait awhile.

2015-01-28 02:50:41
A bad main or rod bearing you mean?
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