return of son of knock, knock
05-18-2006, 10:06 PM
#16
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Hi,
The KLR is only running the boost guage right now.
The timer itself doesn't draw much current, but it can source 100's of ma to drive LEDs. The fact that it can source the current as well as sink it means we can run the 555 output to the LEDs, and return the current thru a ground wire. The more usual approach is to sink the current, which means you have to run the regulated +5v out to the LED, and can add more noise to the +5 rail, not a great idea. So, we can run a ground wire rather than +5v out to the LEDs, and Digikey has some very bright little displays that have 4 embedded LEDs in them, so draw is about 40ma instead of 10ma for a single LED.
I'll try it out soon, but I must say I hope I never see it go off.... On initially setting up the Motec fuel map,I had a bad cell in at about 150 kpa and 4000RPM, and it knocked as it went thru that cell, more of a buzz, and I never, ever want to hear it again. Already have an ugly, scuffed J&E piston on my bookshelf from no oil squirting on #4.
Anyway, I'll let you know what I find out, although I'm not sure how to test it except bang on the block. Not likely to get many volunteers, either.
Thanks,
Reyk
The KLR is only running the boost guage right now.
The timer itself doesn't draw much current, but it can source 100's of ma to drive LEDs. The fact that it can source the current as well as sink it means we can run the 555 output to the LEDs, and return the current thru a ground wire. The more usual approach is to sink the current, which means you have to run the regulated +5v out to the LED, and can add more noise to the +5 rail, not a great idea. So, we can run a ground wire rather than +5v out to the LEDs, and Digikey has some very bright little displays that have 4 embedded LEDs in them, so draw is about 40ma instead of 10ma for a single LED.
I'll try it out soon, but I must say I hope I never see it go off.... On initially setting up the Motec fuel map,I had a bad cell in at about 150 kpa and 4000RPM, and it knocked as it went thru that cell, more of a buzz, and I never, ever want to hear it again. Already have an ugly, scuffed J&E piston on my bookshelf from no oil squirting on #4.
Anyway, I'll let you know what I find out, although I'm not sure how to test it except bang on the block. Not likely to get many volunteers, either.
Thanks,
Reyk
05-19-2006, 01:20 PM
#17
Race Car
www.lsdiodes.com
Great source for LED's. If you want super-bright wide viewing angle, get the s-flux LED's. I use them for lighting very often.
I'm a little leery of running high intensity LED's from IC's. I almost always use the IC to trigger a transistor to switch the current to the LED. If the spec sheet says the 555 timer will handle it, then give it a go.
I had an episode of bad knock in the past, and if you look at the inside of my engine, you can tell that it did not enjoy it either.
23psi on 87 octane when it leaned out....
It was running so rich before that I could get away with it, I fixed a big boost leak and took it out for a run. Let it knock in 3 bouts before I figured out it was knock. Each time it was 5-6 seconds of knock, and me staring at my boost gauge scratching my head. In retrospect, that noise just makes me sick now.
Great source for LED's. If you want super-bright wide viewing angle, get the s-flux LED's. I use them for lighting very often.
I'm a little leery of running high intensity LED's from IC's. I almost always use the IC to trigger a transistor to switch the current to the LED. If the spec sheet says the 555 timer will handle it, then give it a go.
I had an episode of bad knock in the past, and if you look at the inside of my engine, you can tell that it did not enjoy it either.
23psi on 87 octane when it leaned out....
It was running so rich before that I could get away with it, I fixed a big boost leak and took it out for a run. Let it knock in 3 bouts before I figured out it was knock. Each time it was 5-6 seconds of knock, and me staring at my boost gauge scratching my head. In retrospect, that noise just makes me sick now.
