How can I test Tach off bike?

[Anonymous]

I've got a tachometer from an 1985 GS750 that I'd like to test off of
the bike. I imagine that the Black/Yellow lead will either recieve
pulses or a variable voltage from the ignitor unit but I don't know
which.

Does anybody know what the setup would be to bench test this
device? I imagine that I would feed the Orange lead from the +ive
post of the battery and the Black/White lead from the -ive post of
the battery. Can I feed a variable voltage to the Orange lead to
simulate what would be coming from the ignitor?

What values map to what voltages (e.g. 5V = 3000RPM)?

Thanks,
John

 

[Anonymous]

I finally found the time to read the schematic yesterday and found the answer to one of my questions.

The tachometer has three leads:
1) +ive feed from battery
2) -ve feed from battery
3) one lead from the ignition unit that feeds the right hand coil

The meter's sweep is controlled by the same pulse train that goes to the #2 ignition coil.

Although I couldn't figure out an easy way to recreate the pulse train on the bench< I did test the tach by plugging it into my bike's dash. It took a lot more time and effort but now it's done.

I'm posting my results just in case anybody else was curious about this.

 

[Anonymous]

you most likely could have used a 10:1 transformer and plugged it into the wall to get your pulse.

 

[Anonymous]

That sounds interesting but I don't understand how a transformer is going to provide me with a pulse? As far as I understand transformers, they output a steady-state voltage at a different level than their input. I'd really appreciate it if you would send along more detail about your idea.

Regards,
John

 

[Hap Call]

That sounds interesting but I don't understand how a transformer is going to provide me with a pulse? As far as I understand transformers, they output a steady-state voltage at a different level than their input. I'd really appreciate it if you would send along more detail about your idea.

Regards,
John

I believe that he would be counting on the sinusoidal waveform from the 60 Hz of the wall outlet. You would have to wire it up so that it acted like a step down transformer (i.e. the input voltage would be ten times greater that the output) or you would over voltage the electronics and kill it. Personally, this would be kind of dangerous to both the equipment and the person doing the work if he does not know exactly what he is doing.

I would suggest using a pulse generator. There are normally used on electronic equipment to test digital designs and can be set to operate at 5 V and below, which is where you probably want to run it. You can vary the rate of pulsation to see the tach move through its range. You would have to play with it a little to see if it is dependent on pulse count or if it was dependent on pulse width (how long the pulse is generated) to get the tach reading.

Hap

 

[Jay B]

What

What

Maybe I should have paid more attention in electronics class in school.

 

[earlfor]

Hmmm Hap....verrrrry interesting
brings to mind a thought....
since radio control model transmitters and receivers are pulse code modulation and the receiver output leads to operate the servo's are powered by 4.8 volts and have three wires, +,-, signal, it would seem then you could plug a tach into a receiver output lead and by moving the control stick on the transmitter, get a reading on the tach. RC systems operate on pulse count.
Think this might work?

Earl



[quote="Hap Call
I would suggest using a pulse generator. There are normally used on electronic equipment to test digital designs and can be set to operate at 5 V and below, which is where you probably want to run it. You can vary the rate of pulsation to see the tach move through its range. You would have to play with it a little to see if it is dependent on pulse count or if it was dependent on pulse width (how long the pulse is generated) to get the tach reading.

Hap[/quote]

 

[Hap Call]

Hmmm Hap....verrrrry interesting
brings to mind a thought....
since radio control model transmitters and receivers are pulse code modulation and the receiver output leads to operate the servo's are powered by 4.8 volts and have three wires, +,-, signal, it would seem then you could plug a tach into a receiver output lead and by moving the control stick on the transmitter, get a reading on the tach. RC systems operate on pulse count.
Think this might work?

Earl



[quote="Hap Call
I would suggest using a pulse generator. There are normally used on electronic equipment to test digital designs and can be set to operate at 5 V and below, which is where you probably want to run it. You can vary the rate of pulsation to see the tach move through its range. You would have to play with it a little to see if it is dependent on pulse count or if it was dependent on pulse width (how long the pulse is generated) to get the tach reading.

Hap

[/quote]

That may just work...the big if here is at what voltage the tach actually operates...I was guessing the voltage was in the ballpark of 5 volts because most TTL logic chips (the most common family) operate at this voltage and because the chips are cheap and abundent that would be most likely what Suzuki would use.

Another possiblity is that we are barking up the wrong tree and the tach actually compares the phase angle between two sine waves...this is called a resolver and is used in a lot of industrial applications. I would be surprised if this was the case but I have seen some strange stuff come out of Japan!

Hap

 

[earlfor]

Thanks, Hap, I will have to keep this in mind for something to try if I run into any tach problems.

Earl


[quote="Hap Call"
That may just work...the big if here is at what voltage the tach actually operates...I was guessing the voltage was in the ballpark of 5 volts because most TTL logic chips (the most common family) operate at this voltage and because the chips are cheap and abundent that would be most likely what Suzuki would use.

Another possiblity is that

 

[Anonymous]

I am an electronics technician. When I was in school I designed and built a digital tach. My teacher suggested using a transformewr to test it at home because I couldn't take the sig gen home with me. that is why I suggested it.

What year is your bike? My tach is mechanical.

 

[Anonymous]

Hmmm Hap....verrrrry interesting
brings to mind a thought....
since radio control model transmitters and receivers are pulse code modulation and the receiver output leads to operate the servo's are powered by 4.8 volts and have three wires, +,-, signal, it would seem then you could plug a tach into a receiver output lead and by moving the control stick on the transmitter, get a reading on the tach. RC systems operate on pulse count.
Think this might work?

Earl

Hmm! good idea! Are you an RC modeler as well Earl? Small world
GY

 

[Anonymous]

I am an electronics technician. What year is your bike?

It's valuable to know someone with electronics skills - I hope that you keep posting information for us. My bikes are '85.

 

[Hap Call]

I am an electronics technician. When I was in school I designed and built a digital tach. My teacher suggested using a transformewr to test it at home because I couldn't take the sig gen home with me. that is why I suggested it.

I understand what you wanted to do but I am concerned about a novice wiring up a transformer to a piece of equipment. Yes it is only 110V, but it only takes 1 ampere to kill someone. You have some knowledge of electricity so it would be understandable if you did use the sine wave from your wall outlet.

I am supposed to talk with some lawyers about a case where a young man was killed where I work due to electrocution. I do have a little bit of knowledge about electrical stuff.

Hap

 

[earlfor]

Hey Gerry:

Sure nuff. RC airplanes and helicopters, though mostly heli's these past few years.

Earl

[quote="Gerryy"

Hmm! good idea! Are you an RC modeler as well Earl? Small world
GY[/quote]

 

[Jay B]

Master of it all.

Master of it all.

Damn them choppers are hard to fly.

 

[earlfor]

Re: Master of it all.

Re: Master of it all.

jay
There's a simple key to sucess with a chopper. Practice, practice and PRACTICE. Actually though, the secret is setup. If you dont know how to program the pitch, power, and torque curves together correctly, trying to fly it will keep you busier than a six handed monkey at a flea festival. When everything is right on mine, I can put it in a hover 6 feet off the ground and put the transmitter down and walk away, and it will just sit there.

Earl

Damn them choppers are hard to fly.

 

[Jay B]

Chopper

Chopper

Earl,
Many years ago I was into RC Trucks. In fact my son still has the Blackfoot and the dual motor 4 wheeled sterring thing. I was given a chopper by my ex father in law who got fedd up with it. I got it together and running but never flew it. Before I had time to learn it was off to another duty station so it got sent back to California. I've seen them fly and have flown gliders but thats about it. Oh yeah is there anything you don't do?????

 

[earlfor]

Re: Chopper

Re: Chopper

Well Jay, for many years I have thought it would be a real hoot to
drive a 57 chevy out the back door of a C-130, but I probably will never get the opportunity.

Earl

Earl,
Many years ago I was into RC Trucks. In fact my son still has the Blackfoot and the dual motor 4 wheeled sterring thing. I was given a chopper by my ex father in law who got fedd up with it. I got it together and running but never flew it. Before I had time to learn it was off to another duty station so it got sent back to California. I've seen them fly and have flown gliders but thats about it. Oh yeah is there anything you don't do?????

 

[Bill + Karen]

Re: Chopper

Re: Chopper

Well Jay, for many years I have thought it would be a real hoot to
drive a 57 chevy out the back door of a C-130, but I probably will never get the opportunity.

I am curious about the minor details on this one. With or W/O parachute? Planning on landing on a large air bag? Do tell, perspirering minds want to know! Safe Riding, Bill

 

[mcycle-nut]

Re: Master of it all.

Re: Master of it all.

Damn them choppers are hard to fly.

Hard to ride too, especially the hard tails.... :lol: