Arduino as tachometer

Hey :slight_smile: I'm new to the whole arduino world, and was wondering if it's possible to rig an arduino to a small diesel motor to use it as a tachometer? I've looked into it and people say it needs an alternator, which it doesn't have...
Thanks :slight_smile:

You need some sort of sensor to read the output shaft revolutions. There are many possibilities: Hall effect sensor, slotted disk optical interrupter, tachogenerator, etc.

The Arduino would read that and display the result.

The main question I have is where would I have to hook it up to get said reading as it doesn't have an alternator?

The "alternator", missing or not, has nothing to do with it.

The sensor reads the revolutions of the motor shaft. That is what you want to know, isn't it?

Yes, but that brings another issue. Will post a picture in 5 minutes or so.

The shaft is running to a pump motor of which I can’t access.

That would not be an Arduino problem.

As in it wouldn't be a problem for it? Or it's not suited to do that?

The Arduino just reads a sensor. If there is no place to attach a sensor, you may have to pick another project.

Not really a project. We need it for our work equipment. The only other option is pay $1600 for a tachometer. Which we don't really want to do.

That is a totally unreasonable price. You could try to figure out how/where the tachometer is attached. If you come up with something, let us know!

That's why I'm here haha. The base model is 1600, the high end one is 6000. So yea trying to find a way around it haha. Just wondering if anyone else had figured something out in the past with one :stuck_out_tongue:

There is ALWAYS a place for a sensor. Is your Diesel air cooled with a fan or water cooled with a radiator and fan?

Is the pump directly connected to the crank shaft, or through a flexible/u-joint? Does your Diesel have a flywheel? Does it have an electric starter or does it have a hand crank? Is it a single cylinder? Does it have high-pressure tubing to the injectors?

Come on, think about the engine you want to monitor, can you see any moving part????

Paul

Air cooled, direct to crank, with flywheel, electric start, single cylinder, and no high pressure tube to injectors.
It's a yanmar motor with a powamac pump, if that helps at all.

Tawmeh:
Air cooled, direct to crank, with flywheel, electric start, single cylinder, and no high pressure tube to injectors.
It's a yanmar motor with a powamac pump, if that helps at all.

Thank you.

Can you attach a reflective material or paint to a spot on the fan? Can you attach a piezo to the exhaust?

Paul

i believe you could put a piezo in with very little/no issue.

Tawmeh:
i believe you could put a piezo in with very little/no issue.

This afternoon I took a bit of time to Google "piezo tachometer" and found several commercial units available. So the concept is not new and readily accomplished.

Your next step, if you decode to go there, is to make a bracket or mount that is waterproof and heat proof and be able to attach to the exhaust system. You are lucky in that the engine has just one cylinder and is 4 cycle, so 2 revs per exhaust pulse.

Paul

This afternoon I took a bit of time to Google "piezo tachometer" and found several commercial units available. So the concept is not new and readily accomplished.

As I understand the "piezo tachometers" they are based on the fuel injection pressure and not the exhaust.

From post 13

no high pressure tube to injectors.

Maybe the OP will be able to adapt the concept to exhaust pressure.

I've also seen reverence to an "acoustic tachometer" which is a phone app for deriving engine speed from the sounds.

I am still very unclear why there is no access to a rotating piece of the engine. I'd consider drilling a hole through the flywheel bell housing.

How do the tachometers which the vendor sells for the high prices work? What signal do they use for rpm.

cattledog:
As I understand the "piezo tachometers" they are based on the fuel injection pressure and not the exhaust.

From post 13
Maybe the OP will be able to adapt the concept to exhaust pressure.

I've also seen reverence to an "acoustic tachometer" which is a phone app for deriving engine speed from the sounds.

https://play.google.com/store/apps/details?id=com.javiery.rpmgauge&hl=en

I am still very unclear why there is no access to a rotating piece of the engine. I'd consider drilling a hole through the flywheel bell housing.

How do the tachometers which the vendor sells for the high prices work? What signal do they use for rpm.

SEveral of my Google hits show either one of the pressure pipes going to an injector may be used or the exhaust impulse may be used with their equipment. All they are looking for is the shock impulse in the metal.

Should be and easy programming job. The difficulty will be in the mounting. Diesel exhausts are rather cool compared to gasoline engines.

Paul