DIY Knock gauge
- Thread starter blueta
- Start date
yea, the 3914... I made a VU meter outta one of them once... yea, that will simplify it a bit... it takes analog input to vary the amount of LEDs that it triggers. I like the photocell to vary LED brightness... a trimmer would work just as well too... LEDs draw so little, i just keep them on near their normal fwd current anyways, unless your using high intensity ones - at night some can get nasty bright.
then again you learn a lot less just throwing the parts together.
Phil
then again you learn a lot less just throwing the parts together.
Phil
salvageV6
Daily Driver
- Joined
- May 25, 2001
That's a simple enough one.
All my 3914's are tied up in my boost display.
They are about $7 each and work great.
You could tie the beeper to the output as well via a transistor switch.
Lots of options with that chip.
I just realized the cheap counter I wanted to use will only light one LED at a time not sequentially so it would still read the peak count just not be as visible which kind of defeats the purpose.
The 3914 will work in dot or bar graph mode and bar graph is easier to see.
All my 3914's are tied up in my boost display.
They are about $7 each and work great.
You could tie the beeper to the output as well via a transistor switch.
Lots of options with that chip.
I just realized the cheap counter I wanted to use will only light one LED at a time not sequentially so it would still read the peak count just not be as visible which kind of defeats the purpose.
The 3914 will work in dot or bar graph mode and bar graph is easier to see.
salvageV6
Daily Driver
- Joined
- May 25, 2001
Has anyone actually built that one in the circuit shown with the 3914?
If so I am interested in how it resets, do you add a switch or does it lose voltage on a decay at the input to the 3914.
I started building the one we designed with 2 EST counts per LED.
Seems to work okay so far on the bench, I got the input conditioning and flip flop divide by 2 circuit done.
I have to finish the counter and add the timers for reset upon power up and reset upon 30-40 seconds after detecting knock pulses.
If so I am interested in how it resets, do you add a switch or does it lose voltage on a decay at the input to the 3914.
I started building the one we designed with 2 EST counts per LED.
Seems to work okay so far on the bench, I got the input conditioning and flip flop divide by 2 circuit done.
I have to finish the counter and add the timers for reset upon power up and reset upon 30-40 seconds after detecting knock pulses.
salvageV6
Daily Driver
- Joined
- May 25, 2001
Both the turn on 2 second reset timer and the approximately 30 second reset timer (adjustable) after knock registers are done and working.
Took a bit of thinking to get the simple 555 timers to work properly with the signals at hand but we got it done with on board components already, namely by using the second D flip-flop in the divide by 2 counter scheme.
So there will be no divide by 4 counter scheme option, but I believe that's too many EST pulses to be ignoring anyways.
Now to work on some audible timers with a buzzer and beeper.
Gonna do 2 different signals, buzzer and beeper, instead of a long and short beep on one signalling device.
Each will be about 2 seconds in duration once a certain LED is lit or surpassed.
The final installation of those can easily be changed by the builder to suit their desired db level and tastes for those alerts.
The circuit board became a bit messy since I installed my display LED's on it for testing, the final version most likely would have a ribbon cable to a smaller display or could be incorporated into a self built gauge face type display, LED colors and brightness can be user implemented as well.
Took a bit of thinking to get the simple 555 timers to work properly with the signals at hand but we got it done with on board components already, namely by using the second D flip-flop in the divide by 2 counter scheme.
So there will be no divide by 4 counter scheme option, but I believe that's too many EST pulses to be ignoring anyways.
Now to work on some audible timers with a buzzer and beeper.
Gonna do 2 different signals, buzzer and beeper, instead of a long and short beep on one signalling device.
Each will be about 2 seconds in duration once a certain LED is lit or surpassed.
The final installation of those can easily be changed by the builder to suit their desired db level and tastes for those alerts.
The circuit board became a bit messy since I installed my display LED's on it for testing, the final version most likely would have a ribbon cable to a smaller display or could be incorporated into a self built gauge face type display, LED colors and brightness can be user implemented as well.
salvageV6
Daily Driver
- Joined
- May 25, 2001
Buzzer and beeper are done.
Just have to tweak the duration of each via a resistor change to make them more equal. Beep is too short and buzzer is just annoying enough to get your attention. About 2.5 seconds long.
Easily can be made adjustable with a potentiometer turned into a variable resistor, (cut one end leg off), if desired in the final version.
I have to build a bounceless switch to test counting pulses one by one accurately since right now I'm using a grounded clip lead that gives me anywheres from 1 to 10 pulses everytime I touch it to the circuit input.
Once accuracy is verified I will start on the 3rd gear only KR reading and see if that's doable.
Finally will be incar tests next week sometime.
Getting bored with it since it's working now, probably will never get to doing the schematics. :tongue:
Just have to tweak the duration of each via a resistor change to make them more equal. Beep is too short and buzzer is just annoying enough to get your attention. About 2.5 seconds long.
Easily can be made adjustable with a potentiometer turned into a variable resistor, (cut one end leg off), if desired in the final version.
I have to build a bounceless switch to test counting pulses one by one accurately since right now I'm using a grounded clip lead that gives me anywheres from 1 to 10 pulses everytime I touch it to the circuit input.
Once accuracy is verified I will start on the 3rd gear only KR reading and see if that's doable.
Finally will be incar tests next week sometime.
Getting bored with it since it's working now, probably will never get to doing the schematics. :tongue:
salvageV6
Daily Driver
- Joined
- May 25, 2001
Building up the bounceless switch for testing pulses individually probably work on it later tonight.
Found 2 glitches in the unit. :frown:
One was, I was using the last green LED and when it shut off it signalled the buzzer to go off. Therefore if the last green light was lit due to KR and then the reset pulse came and shut it off after the 35 seconds it also set the buzzer off upon reset. Not bothersome really and you knew exactly how much KR was present during the reset but it's not the way I wanted the thing to work.
Had to add 2 transistors to trigger the buzzer and beeper to go off when a certain light lit up not when the previous one shut off.
555 timers are ground pulse triggered and not like other timers (one-shots) that you can use a rising or falling edge of a signal to trigger.
The 4525 CMOS one shot chip would be the one to use for either edge pulse triggers but I didn't have any lying around and the 555 circuits were built.
But that glitch is worked out and I put the buzzer on the first yellow LED, 8 EST pulses, and the beeper on the first red LED 14 pulses total I believe.
One other minor glitch is the first reset after KR is triggered is a bit lower than the subsequent reset times.
I have it cranked up to about 35/40 seconds for reset and the first one is about 20/25 seconds in duration, no biggy since it's longer than some existing product out there.
I haven't started on the 3rd gear only operation yet but it shouldn't be too hard to make work although we only have one logic NAND gate left.
I probably will remote the buzzer, beeper, and LED's before in-car testing so that will put the whole deal off a week or so.
In the Lab. testing will still be going on.
I may try building the 3914 circuit above as well which is much simpler to construct but I am not sure how well it will operate.
Found 2 glitches in the unit. :frown:
One was, I was using the last green LED and when it shut off it signalled the buzzer to go off. Therefore if the last green light was lit due to KR and then the reset pulse came and shut it off after the 35 seconds it also set the buzzer off upon reset. Not bothersome really and you knew exactly how much KR was present during the reset but it's not the way I wanted the thing to work.
Had to add 2 transistors to trigger the buzzer and beeper to go off when a certain light lit up not when the previous one shut off.
555 timers are ground pulse triggered and not like other timers (one-shots) that you can use a rising or falling edge of a signal to trigger.
The 4525 CMOS one shot chip would be the one to use for either edge pulse triggers but I didn't have any lying around and the 555 circuits were built.
But that glitch is worked out and I put the buzzer on the first yellow LED, 8 EST pulses, and the beeper on the first red LED 14 pulses total I believe.
One other minor glitch is the first reset after KR is triggered is a bit lower than the subsequent reset times.
I have it cranked up to about 35/40 seconds for reset and the first one is about 20/25 seconds in duration, no biggy since it's longer than some existing product out there.
I haven't started on the 3rd gear only operation yet but it shouldn't be too hard to make work although we only have one logic NAND gate left.
I probably will remote the buzzer, beeper, and LED's before in-car testing so that will put the whole deal off a week or so.
In the Lab. testing will still be going on.
I may try building the 3914 circuit above as well which is much simpler to construct but I am not sure how well it will operate.
I don't do "hardware" anymore soooo....
This device could be done in about 10 minutes with a microcontroller and about 20 lines of code - I have no use for one since I don't even look at knock - to me if you're knocking, your already too late whereas AFRs and EGTs will tell you sooner as you creep up on the tune. Besides KR is built into DFIs; but anyways maybe this may kickstart someone (besides me to just build this thing and get it over with) :
Here's some pseudo C code for the record (of course the calibration counts need be just scaled for whatever the ESC counts to degrees retard ratio is - u look it up, I dont feel like it):
int count, signal; // global
count =0; // intialize to 0 on device startup
while(TRUE)
{
signal=read adc(Portwhatever);
// read at total execution delays under clock speed
delay; // time this delay to have a rough timebase for counting pulses
// you could also use an interrupt scheme but I don't think this task is
// involved enough to require the timing accuracy an interrupt would provide
if(signal < 50) // guesstimate based on 8 bit adc - provides low detection...
// you could also use a digital input, but this way i can define an analog noise
// thresholding for triggering.
count++;
// Drive some stinkin LEDS - if you were cool you'd use an LCD - but that's
// easy too! :
if(count>10)
LED1 ON;
if(count>15)
LED2 ON;
// and so on...
if(count > maximum possible KR - yea your engine's dead here )
{
LED3 ON;
delay; // add big ol delay here to make sure you know the crank went thru
// the block. :tongue:
}
delay; // eliminate some LED "flicker"
count = 0; //rst counting
} // end while(TRUE)
that's the basic idea... :redface:
Phil
soooo....This device could be done in about 10 minutes with a microcontroller and about 20 lines of code - I have no use for one since I don't even look at knock - to me if you're knocking, your already too late whereas AFRs and EGTs will tell you sooner as you creep up on the tune. Besides KR is built into DFIs; but anyways maybe this may kickstart someone (besides me
to just build this thing and get it over with) :Here's some pseudo C code for the record (of course the calibration counts need be just scaled for whatever the ESC counts to degrees retard ratio is - u look it up, I dont feel like it):
int count, signal; // global
count =0; // intialize to 0 on device startup
while(TRUE)
{
signal=read adc(Portwhatever);
// read at total execution delays under clock speed
delay; // time this delay to have a rough timebase for counting pulses
// you could also use an interrupt scheme but I don't think this task is
// involved enough to require the timing accuracy an interrupt would provide
if(signal < 50) // guesstimate based on 8 bit adc - provides low detection...
// you could also use a digital input, but this way i can define an analog noise
// thresholding for triggering.
count++;
// Drive some stinkin LEDS - if you were cool you'd use an LCD - but that's
// easy too!
:if(count>10)
LED1 ON;
if(count>15)
LED2 ON;
// and so on...
if(count > maximum possible KR - yea your engine's dead here )
{
LED3 ON;
delay; // add big ol delay here to make sure you know the crank went thru
// the block. :tongue:
}
delay; // eliminate some LED "flicker"
count = 0; //rst counting
} // end while(TRUE)
that's the basic idea... :redface:
Phil
salvageV6
Daily Driver
- Joined
- May 25, 2001
Mines sitting in the chair next to me. Schematic is half done on the rough copy and it will need to be done on large paper so a picture can be made so that it can be read on the internet.
It has lots of parts but it worked well on initial testing.
Should be better than what's out there since it's very customizable to what the owner needs/wants, assuming they have decent proto-circuit board wiring skillz.
I'd do a bit more in-car testing on it before I posted the schematic.
However right now I'm testing a KR detector that has individual cylinder KR recognition that a smart person from out West designed and built 15-20 years ago. So far it works well.
Not much KR at lower boost in my car with the snow tires on it.
KR is very even on my car on all cylinders whilst cranking over.
Thanks for bringing this one back up, I almost feel guilty for not finishing it.
It has lots of parts but it worked well on initial testing.
Should be better than what's out there since it's very customizable to what the owner needs/wants, assuming they have decent proto-circuit board wiring skillz.
I'd do a bit more in-car testing on it before I posted the schematic.
However right now I'm testing a KR detector that has individual cylinder KR recognition that a smart person from out West designed and built 15-20 years ago. So far it works well.
Not much KR at lower boost in my car with the snow tires on it.
KR is very even on my car on all cylinders whilst cranking over.
Thanks for bringing this one back up, I almost feel guilty for not finishing it.
salvageV6
Daily Driver
- Joined
- May 25, 2001
Once the bounceless KR switch was made, and the unit was tested on the bench power supply with simulated KR all functions operated at all levels of KR so that's not an issue.
However in car testing is done to find glitches and power supply issues IE. battery and alternator voltages vary considerably from a test power supply even if you vary it manually to see the range of operation on the bench.
Need to make sure there's no false triggering, KR lights false triggering and worse yet, beeper glitches or latching noise makers, etc. in the car, so far there hasn't been any.
Unlike the current available product....
And we need to know we are counting all the KR pulses from the actual KR line so we will compare this gauge to the Kenne Bell one I have which counts each pulse.
And I personally have no intention of lighting the thing up on my car all the way.
It would also be easy to build one with customizable KR trigger of an emergency DIY alky. pump to supplement the fueling and eliminate KR.
However in car testing is done to find glitches and power supply issues IE. battery and alternator voltages vary considerably from a test power supply even if you vary it manually to see the range of operation on the bench.
Need to make sure there's no false triggering, KR lights false triggering and worse yet, beeper glitches or latching noise makers, etc. in the car, so far there hasn't been any.
Unlike the current available product....
And we need to know we are counting all the KR pulses from the actual KR line so we will compare this gauge to the Kenne Bell one I have which counts each pulse.
And I personally have no intention of lighting the thing up on my car all the way.
It would also be easy to build one with customizable KR trigger of an emergency DIY alky. pump to supplement the fueling and eliminate KR.
