 Tach testing! |
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| -JR- |
 Jan 16 2005, 07:58 PM
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#1
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Life goes faster at 150MPH  Group: Members Posts: 276 Joined: 12-May 04 From: Victoria BC Canada Member No.: 2,055  |
No this isn't a thread on how high you can rev your 914. Ha ha...
I'm wondering if anyone has a creative way of testing a tach on a bench? I had noticed my tach was very "flippy" and seemed to go all over the place. So I want to run it on the bench and see if I can't cut some of that out. The acuracy of the rpm input signal doesn't matter as long as it will deflect the needle. Thanks! -JR- |
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| -JR- |
Jan 16 2005, 10:00 PM
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#2
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Life goes faster at 150MPH Group: Members Posts: 276 Joined: 12-May 04 From: Victoria BC Canada Member No.: 2,055 |
Any thought's anyone? Thanks!
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| Mark Henry |
Jan 16 2005, 10:13 PM
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#3
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
Replace it with an Autometer tach (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif)
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| 914GT |
Jan 16 2005, 10:15 PM
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#4
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Senior Member Group: Members Posts: 1,100 Joined: 11-October 04 From: Tucson Member No.: 2,923 Region Association: Southwest Region |
I built a 555 timer circuit with a mini rotary switch to select resistor values for 1000 - 7000 rpm in 1000 rpm steps (freqs based on 8 cylinder in my case). I have the 555 switch a transistor (open collector) connected to a relay coil (used for inductance). This makes a waveform that's pretty close to a real ignition system, but I'm thinking of using a real ignition coil instead.
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| scotty914 |
Jan 16 2005, 11:04 PM
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#5
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suby torque rules Group: Members Posts: 1,525 Joined: 20-July 03 From: maryland, the land of 25 year Member No.: 924 |
real easy, and you own evrything to do it except a 2 dollar part
hook the tach up to a battery for the hot and the ground take another wire to the ground through a small micro switch from radio shack on the NO contact. the micro switch looks like a 3/4 ich by 1/2 inch black piece of plastic with a metal lever sticking out. take another wire from common contact tot he connection on the tach for the coil now the micro switch acts like the points you just need a way to open and close it very quikly, like a drill and a flapper sander or any thing the acts like a cam to turn the switch on and off when it rotates. the faster the switch turns on and off the faster the tach shows |
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| DJsRepS |
Jan 17 2005, 05:30 AM
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#6
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Member Group: Members Posts: 431 Joined: 4-November 04 From: Sarasota Florida Member No.: 3,060 |
A jumping tac usually a loose wire or point and cond trouble. Try Petronics loose the points if you havnt already
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