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Maybe I'm tone deaf or something. When Steve set my idle mix screws, I was amazed at the subtlety of the change in rpm. He and Rob were both able to hear the adjustments Steve was making, but I couldn't detect the change. So I was wondering if there were any tools that might help me out with this.
I knew the model airplane crowd used to use audio tachometers for tuning their engines, but I wanted something free, of course. I found this. This is a software tool that uses a PC's microphone to detect audio pulses and convert them to an rpm figure. There are also Android and iPhone apps that do this, but the only Android app isn't free. Dunno about iPhone versions.
The software is designed for electric helicopters, so it assumes it's counting pulses from rotor blades passing the mic. It has settings for 2, 3, 4, or 5 blade rotors. 4-stroke inline 4 engines create two exhaust pulses per rev, so set the software for 2 blades. Twin riders will have to double the output for 2 blades, since monocopters aren't supported. There are also sliders for upper and lower rpm ranges. I think these control software filtering of noise that might confuse the reading.
I just tested this against my 850's tach, and it does work. The main limitation seems be resolution lower than the number of significant figures displayed. The real resolution is some fraction of 100 rpm (for two blades). The update speed of 1 second is a bit of a nuisance.
Not too surprisingly, the 850's tach reads some significant percentage lower than the software reads. I didn't take the time to study the error since the garage was getting a bit poisonous, even with the door open. I think this could be used to calibrate the tachometer for those interested, in a way similar to calibrating a speedometer against the GPS. The filter sliders don't go high enough for a bike's redline, but you could probably use the blade count to get a multiplier that would give useful results.
Take it or leave it, there it is. It's free, but not open source. Binaries only, so buyer beware. Keep your laser, um, anti-virus handy. The computer is your friend. You don't have to laugh if you didn't get the reference there.
I knew the model airplane crowd used to use audio tachometers for tuning their engines, but I wanted something free, of course. I found this. This is a software tool that uses a PC's microphone to detect audio pulses and convert them to an rpm figure. There are also Android and iPhone apps that do this, but the only Android app isn't free. Dunno about iPhone versions.
The software is designed for electric helicopters, so it assumes it's counting pulses from rotor blades passing the mic. It has settings for 2, 3, 4, or 5 blade rotors. 4-stroke inline 4 engines create two exhaust pulses per rev, so set the software for 2 blades. Twin riders will have to double the output for 2 blades, since monocopters aren't supported. There are also sliders for upper and lower rpm ranges. I think these control software filtering of noise that might confuse the reading.
I just tested this against my 850's tach, and it does work. The main limitation seems be resolution lower than the number of significant figures displayed. The real resolution is some fraction of 100 rpm (for two blades). The update speed of 1 second is a bit of a nuisance.
Not too surprisingly, the 850's tach reads some significant percentage lower than the software reads. I didn't take the time to study the error since the garage was getting a bit poisonous, even with the door open. I think this could be used to calibrate the tachometer for those interested, in a way similar to calibrating a speedometer against the GPS. The filter sliders don't go high enough for a bike's redline, but you could probably use the blade count to get a multiplier that would give useful results.
Take it or leave it, there it is. It's free, but not open source. Binaries only, so buyer beware. Keep your laser, um, anti-virus handy. The computer is your friend. You don't have to laugh if you didn't get the reference there.
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