Tachometers

[leshoman]

With the tiny tach and the TTO I tried every combination from 1/2" long parallel to plug wire to 2" long parallel 1 wrap to 6 wraps. Covered with alum foil. Made differance but has never seemed to work above 3000 rpm

[Steve]

In the interest of safety and providing Tach user experiences by others flying Vw's, I'm cross-posting this exchange from the Teenie2 group:

>
Doug,

I agree with Brian. Don’t hook up a tach to the P lead of a mag, or the negative side of a n ignition coil if running a distributor/coil ignition. The risk of the tach shorting out the mag or ignition coil is too great. I had it happen to me as well. I was running a distributor/coil based ignition and sho nuff’ my Teenie became a glider on takeoff.

A Tiny Tach picks up the ignition signal inductively. The ‘antenna’ wire is wrapped around a plug wire. This doesn’t present a shorting threat like connecting a tach signal wire to the mag P lead or ignition coil negative terminal would. I attempted to use a Tiny Tach twice but both of them kept locking up. After talking to the nice people at Tiny Tach, they concluded my ignition system was too ‘noisy’ for a Tiny Tach. It seems the newer Tiny Tachs are more sensitive than the older units and more prone to being negatively affected by ignition ‘noise’.

I’ve since changed my ignition system from a distributor/coil ignition system to the Compufire DIS-IX electronic ignition. This ignition system has a tach adapter hooked to it that incorporates a short isolator to prevent a tach from grounding the coil packs. I also installed a second isolator. Once bitten twice shy!

Have fun preparing your Teenie!

Tom
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[Sparrow]

Hay Joe,  U said:
am now running a commercial version of the tiny tack which is doing ok at about 40 hours.
would you mind sharing the name and model number of the commercial version please.

Thanks,

John L.

[Sam Buchanan]

Hay Joe,  U said:
am now running a commercial version of the tiny tack which is doing ok at about 40 hours.
would you mind sharing the name and model number of the commercial version please.

Thanks,

John L.

http://www.tinytach.com/commercial.php

[Sparrow]

Thanks for fielding that question Sam.

Have a great day,
John L.

[Pradeep ks achary]

Well after a productive day of testing tachs I can say the following.
If engine is making noise it must be running. More noise more RPM, less noise less RPM.
I added a ground from fuselage to engine.
set the tiny tach up and run exterior to aircraft and wrapped it around plug wire adjacent to plug and ground.
The TT (Tiny Tach) and the TTO (trail tech, similar to tiny tach) read the same within about 5 or 10 rpm except for some reason the tiny tack was reading 1/2 the RPM, but both agreed thru out the RPM ranges.
The HTDT, (high tech digital tach) agreed with the WT (westach) and the TT and TTO up to about 2,800 RPM, then things got strange.
Full power in level flight resulted in 3,600 on the HTDT, 3480 on TT and TTO and 4400 on the WT, my hall effect meter, which seems to agree with the GPS in two direction flight and averaging was showing 63-65 mph. 
Pointed down hill at full power till HTDT read 3,700, TT and TTO read 3,600, WT read 4400.
At 3000 on the TT and TTO, HDTD 3400, WT 4000. 
I have concluded the WT readings are totally worthless.
I suspect the HTDT is most accurate but it is very possible all are off.
If it was not for the high fuel consumption and working with Frank to get a new prop for this thing I would not worry about this stuff and throw the tachs away. 
Back to the Drawing board.
Got some good video later in the day.
 

[leshoman]

I am working on a project and i stalled a TTO tach, had fairly good luck with them, but cannot get to work consistently and thru engine speed range so i went to amazon and got the cheapest tiny tach knock off and it works from idle to WOT.   FYI

[rfeenstra]

Never had any luck with my TT on a continental A65.  Available - cheap!

[Dan_]

This guy seemed to get his to work on a shielded mag cable...  Not without some consternation however.

http://www.bowersflybaby.com/tech/tach.html