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[nock]

before i made this, i pretty much thought, like most other people, that the only det can thats worth a shit was a bolt and hose. until i went to harbor feight one day.

https://www.youtube.com/watch?feature=player_detailpage&v=t4mZ2FMLC4A

if you are thinking of making or buying an eletronic det can make this one frist and save yourself a whole bunch of fucking around.

[walter]

well, i really dont understand very well listening english, a diy with another recorded video about how good that works should be great!!.

[PhilStubbs]

I just read plugs. I have never met a better tuner than me that uses det-cans.

[ratcityrex]

Leed uses det cans and reads plugs. I believe James at speed factory uses det cans too.

[PhilStubbs]

I have never met either of them. Lol

[nock]

You need it all. I'm usually screwing around on an engine dyno, and regular det cans just are not loud enough for that. I had actually started building a charge amp myself using the same chip as the hf stethescope. Anyhow I have done a lot of screwing around with this and there is a thousand bs write ups out there about building electronic det cans. I have tried most of them, this is far and away better. If you need (not everybody needs or even uses one) an electronic det can, this is better then anything else you can build. I'll try and post some audio of the different sensors and such. But I'm not sure that will show difference. Most of my old det cans, if I could hear them at all, knock sounded like rain on a metal roof, or marbles In a jar, or something like that. With this one it just sounds like knock and that's it, lifters sound like lifters, piston slap sounds like piston slap. Not guessing is good. To me it sounds just like a regular det can (bolt and hose style) just way louder.

[rawr]

Why dont you just buy an accelerometer and quit fucking around?

Its like 150 for an acellerometer with the freq response and sense that youd need and then you just need a charge amp and a little ni daq card to read your shit.


A sens of 10 mv/g should be cool for an engine and 10-10khz for freq response. You can get 20 khz sensors but as long as you get one where youre not hitting resonant frequency you can use a charted value. Ill calibrate your shit on the ninja to nist traceable standards for 100 bucks but you shall revieve no paperwork and if you send me somthing thats not pcb, dytran, endevco, umholtz or kistler, ill send it back so you can stick it up your ass.  Or i could be really nice and teach you how to take an old subwoofer a sig gen and an a.(car stereo, synth, skinflute, whatever) amplifier so you can learn how to calibrate these fuckers on the ghetto.

[rawr]

Not trying to be a dick because the video was cool and useful but those acells are probably not very acurate and i dont want to see you waste smarts and time replicating equipmemt thata not too ecpensive in the first place. Not correcting my typing because android is bullshit.

[DSMR]

Great job! I now have another thing to pick up from HF. Would love more specifics on which sensor you are using and how you hooked it up. Thanks

[Foowee]

I'm getting one.  Caleb you can come down n listen if ya want...  I like finding stuff that is 90% built already n just needs a little tweaking to do what I need.  Thanks Nock!

[rawr]

Id like to check the freq response if you do build one but i dont want to get busted at work

[HiProfile]

If it kicks ass for a person who can make plumbing hardware work, why calibrate it? Why build something 5x the price?

Its like spending $2k on a turbo with ceramic ball bearings, extended tips, anti-surge, dual scroll, etc, when an old hx35 will already win the races for you. Just sayin.

[nock]

If it kicks ass for a person who can make plumbing hardware work, why calibrate it? Why build something 5x the price?

Its like spending $2k on a turbo with ceramic ball bearings, extended tips, anti-surge, dual scroll, etc, when an old hx35 will already win the races for you. Just sayin.

if a regular det can works then use it. some people just use the plugs and dont listen at all. this is just lounder then a regular det can and isnt a total fail like all the other diy electronic ones.

[rawr]

If it kicks ass for a person who can make plumbing hardware work, why calibrate it? Why build something 5x the price?

Its like spending $2k on a turbo with ceramic ball bearings, extended tips, anti-surge, dual scroll, etc, when an old hx35 will already win the races for you. Just sayin.

Because i calibrate shit for a livimg and i consistantly see the weirdest failures from accelerometers. When an accel becomes fucked, they are severely fucked and are not a reliable device for any measurement. Examples being putting out stupid high and low outputs at random areas in the freq range that someone could mistake for preignition but it is not. You also need to know the resonant frequency to make sure you are nowhere near it or youre also going to get nothing but fucked up readings. An accel rated for low frequency use i have seen resonant freq's as low as 3 kHz. If you dont know the frequency response or the senstivity level you could easily be clipping the accel out before acheiving a meaningful reading (even if you lower the charge volts, it doesnt matter) or have an accel that is so neutral that you will not pick up anything ( i dont think most higher range shock accels will pick up engine knock). Mounting is another serious issue that will cause artifical noise. Theres a lot of things to consider before you just throw one on and trust it enough to get accurate readings.

[nock]

pictures...


this is a close up of the 33 ohm resistor that needs to be added

the wires from the knock sensor hook up the same as the original sensor, the sheild connects to bat-

i put a ring terminal on the sheild so eveything inclueding the block is bonded

these are some other sensors ive tested ford and dodge, but the dodge seemed to need a little smaller resister. i stick with the bosch because its wide band and there all the same electricaly.

A-dapter kit

these are some of my other diy internet failures



here is a shitty scematic of the hf stethiscope




to test it i bolted it to the back of a tweater and played some random shit off the internet, this is what i heard...







it works im tellen ya

[rawr]

I believe you i just want to see for my own curiosity>_>

Back of a speaker wont test g levels and youd have to pull some shit to test shock

[nock]

I believe you i just want to see for my own curiosity>_>

Back of a speaker wont test g levels and youd have to pull some shit to test shock

i didnt even do that. just looking for a reason to post porn. havnt done it in a while, felt good.

[92CXyD]

I believe you i just want to see for my own curiosity>_>

Back of a speaker wont test g levels and youd have to pull some shit to test shock

i didnt even do that. just looking for a reason to post porn. havnt done it in a while, felt good.

Well played 

[NoPistons!]

You need it all. I'm usually screwing around on an engine dyno, and regular det cans just are not loud enough for that. I had actually started building a charge amp myself using the same chip as the hf stethescope. Anyhow I have done a lot of screwing around with this and there is a thousand bs write ups out there about building electronic det cans. I have tried most of them, this is far and away better. If you need (not everybody needs or even uses one) an electronic det can, this is better then anything else you can build. I'll try and post some audio of the different sensors and such. But I'm not sure that will show difference. Most of my old det cans, if I could hear them at all, knock sounded like rain on a metal roof, or marbles In a jar, or something like that. With this one it just sounds like knock and that's it, lifters sound like lifters, piston slap sounds like piston slap. Not guessing is good. To me it sounds just like a regular det can (bolt and hose style) just way louder.

Thanks for clarifying.   I need something besides a wideband and datalogging to handle my shit.  Switched my shit around and threw my knock sensor in a bin i have labeled "useless sensor shit i dont like."   seems legit.

[Danbob]

Sorry for dredging up an old thread, but it's a useful one!

I'm currently building a similar device but using a different brand of automotive stethoscope.  I've two questions I'm going Nock or somebody who has also built one could answer.

1.  Did you find it best to use a broadband sensor like the Bosch one! Or would using a tuned resonant sensor designed for that engine bore help filter out background noise?

2.  What is the function of the 33ohm resistor? Where abouts in the circuit did you have to put it?
My PCB is a different layout so I cant follow the photo for reference.  Would different value resistors suit different engine bores? Or is it not relating to that?

Thanks
Dan

[rawr]

Sorry for dredging up an old thread, but it's a useful one!

I'm currently building a similar device but using a different brand of automotive stethoscope.  I've two questions I'm going Nock or somebody who has also built one could answer.

1.  Did you find it best to use a broadband sensor like the Bosch one! Or would using a tuned resonant sensor designed for that engine bore help filter out background noise?

2.  What is the function of the 33ohm resistor? Where abouts in the circuit did you have to put it?
My PCB is a different layout so I cant follow the photo for reference.  Would different value resistors suit different engine bores? Or is it not relating to that?

Thanks
Dan

I can't tell by looking at the back of that board, but I'm assuming its either being used as a voltage divider to get the sensors output in the correct range for the chip so it doesn't sound like noise or its being used to match the impedance of the sensor to what the chip is looking for.  You could probably replace it with a little 100Ohm pot so you can tweak it until it sounds right.

Pretty cringy reading my posts from 6 years ago lol.

[nock]

And back from the dead!

I didn't know anyone still lived here.

Anyway, you are correct the added resister goes right across the biasing resister that is already there. You need to make sure that what you have is actually a charge amp, meant for piezo input, and not just a high impedance op amp. Usually this will be a jfet amp (TL072). There is usually a feedback cap, in the hf stethoscope, the resister goes directly across it. Also don't be a afraid to play around with it. You can't really blow up a change amp unless you smash the sensor with a hammer, or ground the output, or something stupid like that.

Does hf no longer sell this?