Inexpensive Tiny Tach Substitute with replaceable battery

[nlappos 413]

I sprang less than $10 and bought a cheap tachometer/Hourmeter on Ebay (see this link http://www.ebay.com/itm/New-Digital-Tach-Hour-Meter-Tachometer-Gauge-For-2-Stroke-4-stroke-Gas-Engines-/331223584733?hash=item4d1e76cfdd:g:~awAAOxyi-ZTadfo&vxp=mtr)

I bought it and installed it on my Rotax 582, alongside my Tiny Tach. The cheaper knockoff behaves very well, has the same update timing, and is exactly as accurate as the Tiny Tach. The basic workmanship and appearance of this tach is the same as the Tiny Tach, as well. Note that the below version from the same company even has a replaceable battery:

http://www.ebay.com/itm/Digital-Engine-Tach-Tachometer-Hour-Meter-for-Motorcycle-Choppers-ATV-Spark-Plug-/151776852704?hash=item23569afae0:g:9GkAAOSw~gRVzUd7&vxp=mtr

[TJay 1041]

Ha I bought one of those years ago, I never did stick it in a plane, only because I trusted the tiny tach and went that wrought, but I did stick the cheaper one  on my lawn mower and it worked great, never had any issues,

[JustNorm 14]

I bought a few of them.  Had one on a 582 and even use one on my 912.  Fairly accurate but not perfect.  Can miss count once in a while but only for seconds.  I did have one go bad but I also had a tiny tack go bad.  For the money buy two and then you have a spare is one goes bad or put one on each mag and you will have a double check.

 

 

[nlappos 413]

Well that bargain didn't last long. I flew .8 today, and the new tach drifted a bit as compared to the Tiny Tach, about 40 to 160 rpm. I also noted that when I touched the face of the tach it increased to +1000 rpm approx, and restored accuracy when I stopped touching it. The Tiny Tach, of course, shows no such tendency.

[EDMO 1078]

Well that bargain didn't last long. I flew .8 today, and the new tach drifted a bit as compared to the Tiny Tach, about 40 to 160 rpm. I also noted that when I touched the face of the tach it increased to +1000 rpm approx, and restored accuracy when I stopped touching it. The Tiny Tach, of course, shows no such tendency.

Does this tach require grounding?  Could it have been a bad ground, or not good contact w/plug wire, or other interference ?  I bought the one w/replaceable battery for $13.90 just for backup or cross ref. - hoping for better.   EDMO

Edited 12 Sep 2016 by EDMO

[nlappos 413]

Ed,

No grounding, has only one insulated wire for wrapping around plug wire. The response to touching the face seems pressure sensitive, if I push it makes the numbers flip. Probably a loose connection inside the cube. CHEAP.

[Dusty 126]

I use one of each so I can catch a potential ignition problem in flight,3 years on both no problems but a 50 ish rpm difference that seems to be temperature related.

for less than half the price the cheapy wins out

[EDMO 1078]

I use one of each so I can catch a potential ignition problem in flight,3 years on both no problems but a 50 ish rpm difference that seems to be temperature related.

for less than half the price the cheapy wins out

Even cheaper when you buy the one with the replaceable battery.   I don't think the Tiny Tach battery can be replaced.   EDMO

[lostman 198]

Ed, you're correct. I had a Tiny Tach give up the battery's ghost and chipped away at the insulating material on the back. I then went and wired it direct to 12 volt with a resistor to drop the voltage down. It worked that way until I found that I'd put the wrong resistor in line and the voltage was still too high, then it let the factory smoke out too. It was a worthwhile experiment though since I found you can resurrect one of these guys with a little time and obviously more electronic knowledge than I have.

[EDMO 1078]

Ed, you're correct. I had a Tiny Tach give up the battery's ghost and chipped away at the insulating material on the back. I then went and wired it direct to 12 volt with a resistor to drop the voltage down. It worked that way until I found that I'd put the wrong resistor in line and the voltage was still too high, then it let the factory smoke out too. It was a worthwhile experiment though since I found you can resurrect one of these guys with a little time and obviously more electronic knowledge than I have.

We had to do all the electrical and electronics calculations in Aviation School, which gave me a headache - I found that once I let the electrical smoke out of something, it cured my headache!    EDMO

Edited 22 Sep 2016 by EDMO

[chopndrag 226]

I bought a cheap one similar but can't get it to work right . How many wraps did you do and where ? 

[Dusty 126]

4 works for me