Autometer 6871 tach

rallye bob · 05-23-2009, 07:45 AM

Thanks Rod;
The instructions state....... NOTE: Playback tachs, and Playback boxes must have 12 volts applied to the blue wire. Recording will begin when 12 volts is removed......

So if I run the blue wire from, 12 v source through a n/o momentary switch, and then to tach.... I hit the momentary switch just before I leave, and the tach starts recording?
This tells me that the "blue" wire only has to see 12 v for an instant.... Is this true?
As you can tell, I'm not much for understanding auto wiring, and I need lots of help simplifying it... :-(
TIA

Rob Petrie E395 · 05-23-2009, 12:18 PM

These tachs are really made to be wired into the transbrake solonoid so when its released and the 12 volts goes away the tach starts recording beyond the 10 seconds that is already being held in memory so you can get 10 seconds before the run and the auctual run. I tried to figure out a way to put a momentary switch on the throttle linkage of my footbrake car and never found a good way to do it. I ended up putting button on the steering wheel and as soon as the other guy prestages I hit it and stageto give the tach the momentary 12 volts it need to start recording. The bad part of doing it this way is, first its one more thing to do when staging the car and second if the track doesnt have autostart and the other guy takes forever to stage or tries to burn you down it wont record the whole run due to the limit on how long it will record the run. If anybody has a good way to put a monemtary switch on the throttle linkage I would hear about it. At first I tried a NOS microswitch on the throttle body thinking when I went wide open at launch it would trigger the tach but the tach needs to see 12 volts and then starts recording when the 12 volts goes away so that did not work. I tried a couple of other ways but never came up with something I felt was safe and consistant. Again if anybody has something that works and would be willing to share there idea I would like to hear about it.

05-23-2009, 07:45 AM	#1
rallye bob Member Join Date: Sep 2006 Location: Genoa, Illinois Posts: 489 Likes: 9 Liked 6 Times in 4 Posts	Re: Autometer 6871 tach Thanks Rod; The instructions state....... NOTE: Playback tachs, and Playback boxes must have 12 volts applied to the blue wire. Recording will begin when 12 volts is removed...... So if I run the blue wire from, 12 v source through a n/o momentary switch, and then to tach.... I hit the momentary switch just before I leave, and the tach starts recording? This tells me that the "blue" wire only has to see 12 v for an instant.... Is this true? As you can tell, I'm not much for understanding auto wiring, and I need lots of help simplifying it... :-( TIA

05-23-2009, 12:18 PM	#2
Rob Petrie E395 VIP Member Join Date: Dec 2007 Location: Woodlawn IL Posts: 1,092 Likes: 162 Liked 216 Times in 77 Posts	Re: Autometer 6871 tach These tachs are really made to be wired into the transbrake solonoid so when its released and the 12 volts goes away the tach starts recording beyond the 10 seconds that is already being held in memory so you can get 10 seconds before the run and the auctual run. I tried to figure out a way to put a momentary switch on the throttle linkage of my footbrake car and never found a good way to do it. I ended up putting button on the steering wheel and as soon as the other guy prestages I hit it and stageto give the tach the momentary 12 volts it need to start recording. The bad part of doing it this way is, first its one more thing to do when staging the car and second if the track doesnt have autostart and the other guy takes forever to stage or tries to burn you down it wont record the whole run due to the limit on how long it will record the run. If anybody has a good way to put a monemtary switch on the throttle linkage I would hear about it. At first I tried a NOS microswitch on the throttle body thinking when I went wide open at launch it would trigger the tach but the tach needs to see 12 volts and then starts recording when the 12 volts goes away so that did not work. I tried a couple of other ways but never came up with something I felt was safe and consistant. Again if anybody has something that works and would be willing to share there idea I would like to hear about it.