Rehashing old tach idea

[lmichael]

Quite some time ago I inquired about putting a tach on my G2160. I've been doing quite a lot of research. It seems the neatest and cleanest way is to add a "W" wire into my alternator. So I took the alternator off, and removed the back cover. Noticed there were IIRC 6 taps going to the field coils. Everything I've researched and read points to simply tapping off one and running a lead out. So, I have done this. I had some really nice insulated and water proof marine grade 2 wire connectors. So, I tapped off 2 different points. My theory being one point I tapped had multiple of coils bound to it and the other only a single lead. Figured one HAS to work.
Anyone else tried this? If so how did it work? (if it did at all).
I've resigned myself that if it does not work I'll make a bracket to add a proximity sensor to the fly wheel area, or one of those "strap on" sensors on the alternator case. The latter I am wanting to avoid as to me it looks "amateurish". The way I added the leads currently you would have to look REALLY hard to know it's not factory. Neat and clean.

 

[GeoHorn]

I wish my RTV-X900 had a tach. The types I experimented with worked off “vibration” (junk) …or needed a flywheel/harmonic-balancer sensor…(too amateurish as you’ve mentioned).

I wish someone would create a “kit” I could install and be done with it.

 

[lmichael]

Me as well

 

[GreensvilleJay]

curious as to what the internals of the alternator look like. If it's similar to the one on the BX23S, there's a great diagram in the electrical section you could use to properly get the 'tach' signal instead of guessing.
Most alternators are 3 phase units, either delta or why connected so super easy to get 'tach' signal.

 

[lmichael]

curious as to what the internals of the alternator look like. If it's similar to the one on the BX23S, there's a great diagram in the electrical section you could use to properly get the 'tach' signal instead of guessing.
Most alternators are 3 phase units, either delta or why connected so super easy to get 'tach' signal.

Do you mean in the workshop manual? If there is an inclusion of that, I have the entire WSM for this machine. Never dawned on me to look there since the alternator is made by Denso.
As it is it's pretty simple. Just a miniature version of what you would find on pretty much any Toyota.
Think I will have a look.

 

[GreensvilleJay]

I looked at the WSM ,but no 'internals' shown unlike the BX23S drawing.
If you had the actual DENSO info, could look it up and see what's inside to properly wire the 'tach' signal.

 

[lmichael]

Actually already was "inside it". Which is how I found the coils were all terminal ended around the outer area. I simply tied into one of those terminal endings
When I saw this stuff done on other ones people were pretty much simply soldering a wire inside to the same general area I was able to to simply solder on a terminal end, cover that with marine grade shrink wrap. And simply ran the leads under the cover

 

[GreensvilleJay]

Measure the voltage on the wire when running....
Depending on where you wired, you should get either 15 volts AC or 15 volts DC . Easy to see with an oscilloscope, and you'll probably need a burden resistor. As to what your 'tachometer' needs as a signal is anyone's guess.

 

[Russell King]

Try looking for a tachometer here and see if there is any info that helps or just get one of their tachometers.

Exactly what type of tachometer are you trying to install?

 

[lmichael]

Try looking for a tachometer here and see if there is any info that helps or just get one of their tachometers.

Exactly what type of tachometer are you trying to install?

Look here where? Just a cheap one from FleaBay 85mm 0-4000RPM With Hour Meter Tachometer Gauge Diesel Engine 9-32V For Car Boat | eBay
They show an instruction sheet for it. Wired directly to the "W" terminal

 

[Russell King]

Look here where? Just a cheap one from FleaBay 85mm 0-4000RPM With Hour Meter Tachometer Gauge Diesel Engine 9-32V For Car Boat | eBay
They show an instruction sheet for it. Wired directly to the "W" terminal

Tiny tach (forgot to post the link)

Design Technology, Inc. and Tiny-Tach | Design Technology, Inc., Home of Tiny-Tach

Genuine new stock TINY-TACH™, direct from the U.S. manufacturer, at prices lower than many resellers. Ultrasonic Cleaners. Tachs. Timing tools.

www.tinytach.com

 

[lmichael]

Oh, I've looked into Tiny Tach. But I HATE digital things I mean REALLY hate. I want a "dial" and a needle so I can just glance and see what I want
Now if there was a way, TT made only a sensor/sending unit that could feed an analogue tach I would be all over that

 

[Russell King]

I really don’t know much about the altenator and the W wire but did read some about it and what I see is that it is for the tachometer which makes sense. But the Kubota alternators probably never drove the tachometer so you are trying to modify the stock alternator to drive the tachometer I think.

Is that what you are asking —> How does an alternator produce a signal that drives a tachometer?

I don’t think that tying into the winding directly will work but I will have to think about it. I would assume that the signal needs to look like a square wave pattern of off and on signals not a sine wave like the winding is producing. As I understand the magnetic pickup that is the signal that sensor will produce.

I saw a schematic from the link you provided that supports the need for the square wave pattern.

I think I might look into the way the alternator (that has the W wire) is built. From what I saw when BRIEFLY looking they have an onboard regulator that may also condition the signal to square wave. I am pretty sure that there are simple electronic circuits that can be used to make the sine wave become a square wave. I think that could be packaged under the dash to keep it looking better than at the alternator.

Perhaps one of the “electrical” types would be along to suggest what is needed. You could also call Tiny Tach and ask if they can sell you a module to provide the correct signal since they may already provide that with their systems.

 

[lmichael]

Yeah, I guess until I have a tach in hand to try it will be hard to tell. I do have a multi meter that can not only measure AC voltage (so I can make sure it's not exceeding the 15V) but also the frequency of that voltage. What I am assuming here is that the tach is measuring that freq. not the actual voltage level. And equates speed to the freq.
On every video I've seen of adding the "W" term. especially on the Dodge Cummins (which uses nearly the exact same alternator as the Kubota) only "upsized". They simply added a wire to one of the coil connections and hooked that to a tach. I did not see them using any "conditioners" prior to the tach. And these hookups were on Denso alternators. And one thing I have seen about those is about the only difference between the ones on things like the Cummins and Toyota/Lexus products is the physical size and output.

 

[Henro]

Curious why you need a tach…

In 20+ years never “needed” one on my BX2200.

Do use the tach on the B2910 if using the rotary cutter (Brush hog) though…

I do understand want VS need…

 

[lmichael]

I would like it so I can get repeatable results when applying material to my lawn. I put a tach on my old Honda 4514. (along with an oil pressure gauge which I already have for the Kubota now). I was able to set the pressure and volume on my tow behind sprayer for perfect yield by knowing if I set RPM to (IIRC 2200) and set the hydro lever to full mowing speed, I would get the proper yield from my tank.
Now I have to guess at it. I guess instead of a tach I could get a cheap GPS speedometer, and then engine speed would not matter.

 

[GreensvilleJay]

If you're wanting 'ground speed', use an inductive sensor to 'look' at the drive shaft ujoint. You can use this signal to feed a tachometer or 'computer' to decided what 'MPH' you're travelling at.

I did that 40 years ago for applying Phizer selective herbicides 'down east' for Irving. You dialed in the application rate' and just drove, homemade PCB controlled feed rate based on ground speed so didn't matter going uphill, downhill, fast or slow, you got xxx pellets per square foot, acre after acre after acre....

 

[Henro]

I would like it so I can get repeatable results when applying material to my lawn. I put a tach on my old Honda 4514. (along with an oil pressure gauge which I already have for the Kubota now). I was able to set the pressure and volume on my tow behind sprayer for perfect yield by knowing if I set RPM to (IIRC 2200) and set the hydro lever to full mowing speed, I would get the proper yield from my tank.
Now I have to guess at it. I guess instead of a tach I could get a cheap GPS speedometer, and then engine speed would not matter.
View attachment 129319

That makes total sense. Something I never considered since I am satisfied with my 4 or 5 acres of short weeds that look like grass…

 

[lmichael]

If you're wanting 'ground speed', use an inductive sensor to 'look' at the drive shaft ujoint. You can use this signal to feed a tachometer or 'computer' to decided what 'MPH' you're travelling at.

I did that 40 years ago for applying Phizer selective herbicides 'down east' for Irving. You dialed in the application rate' and just drove, homemade PCB controlled feed rate based on ground speed so didn't matter going uphill, downhill, fast or slow, you got xxx pellets per square foot, acre after acre after acre....

Well while I don't care about "actual speed" as all that matters is being able to get a setting dialed in on the sprayer, at whatever RPM/Hydro setting I like and then being able to duplicate that. So, RPM or a speed reading of some kind would work. I just think I'd like a tach better as that along with a true temp gauge and oil pressure gauge and I'll feel better about my orange baby

 

[lugbolt]

they make optical tachs, that could be easily adapted to the crankshaft via pulley or flywheel.