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Topic: Controlling a Tachometer (Read 365 times) previous topic - next topic

ShaunJV12

Dec 23, 2019, 07:45 pm Last Edit: Dec 23, 2019, 07:46 pm by ShaunJV12
Hello,

I am new to the forum and was wondering if anyone would be able to please help me with my project?

I would like to control a tachometer (found here: https://www.aliexpress.com/item/32974405813.html) and I am struggling to work out how to control the needle with the arduino.

I have seen other projects like this and people use the 'tone' function to control the needle however nothing I do seems to work. I have wired the tachometer the exact same was as seen here: https://www.racedepartment.com/threads/arduino-arduino-rpm-tacho.143010/. The goal is to use the tachometer to display the RPM of a model aeroplane engine I have.

Any suggestions would be greatly appreciated, any questions feel free to ask.

Thanks :)

Shaun

jremington

#1
Dec 23, 2019, 08:40 pm Last Edit: Dec 23, 2019, 08:42 pm by jremington
The web page says that the tachometer "runs from a sensor". 

If you don't want to use the specified sensor, you or someone else will need to reverse engineer the internal circuitry of the tachometer, to figure out how to control the indicator needle.

Or, replace the needle motor with one that is Arduino compatible and comes with instructions, like this one.

ShaunJV12

The web page says that the tachometer "runs from a sensor". 

If you don't want to use the specified sensor, you or someone else will need to reverse engineer the internal circuitry of the tachometer, to figure out how to control the indicator needle.

Or, replace the needle motor with one that is Arduino compatible and comes with instructions, like this one.
Normally the sensor is connected to the ECU and then the ECU controls the gauges on the car/bike so I was hoping to emulate the ECU's signal, I just don't know what the signal is, other people seem to use 'tone' but it doesn't work for me. I did think about replacing the needle motor but I was hoping to do it without taking the gauge apart if possible as there are plenty of people on YouTube who seem to have done it without using their own stepper motors.

ballscrewbob

If it is just emulation you need then a MOSFET running 12 volts through it but triggered from the Arduino to get the pulses would be a good option.

See this project for a heads up.

Bob.

It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

jremington

Quote
there are plenty of people on YouTube who seem to have done it
With that exact same gauge?

ballscrewbob

With that exact same gauge?
Or close enough.
A lot of them use a standard wiring set.
ECU's tend to do a lot of the heavy lifting as far as pulses etc.

But for the OP I suspect something a lot easier is doable.

It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

zoomkat

If a "tone" function was used, then 12khz might read out 12,000 rpm. Sounds like it is just pulse driven.
Google forum search: Use Google Search box in upper right side of this page.
Why I like my 2005 Rio Yellow Honda S2000  https://www.youtube.com/watch?v=pWjMvrkUqX0

ShaunJV12

With that exact same gauge?
With that exact same gauge?
No not the exact same gauge unfortunately

ShaunJV12

If it is just emulation you need then a MOSFET running 12 volts through it but triggered from the Arduino to get the pulses would be a good option.

See this project for a heads up.

Bob.


Hi Bob, thank you very much, I tried that sketch and it worked (kinda), I think I need to fiddle about with the settings on the gauge but it's good progress. I bought one gauge and assumed it was broken and then purchased a different one, the first one worked but the other one didn't funnily enough, maybe they work from different frequencies.

ballscrewbob

People around here are always willing to help out, so post what you have exactly and a good description of the exact issues and they will try thier best to get you going.

Just remember the devil is in the details.

Some may need an ignition type pulse and some may just need an ECU pulse of some description.
Working out which is which would be a key factor in success.



It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

ShaunJV12

People around here are always willing to help out, so post what you have exactly and a good description of the exact issues and they will try thier best to get you going.

Just remember the devil is in the details.

Some may need an ignition type pulse and some may just need an ECU pulse of some description.
Working out which is which would be a key factor in success.




Thank you, I do appreciate it. I'm not bad with Arduino's but for some reason simple project is really giving me issues I am struggling with. Today I installed the SimHub software which should at least allow me to test the gauges that way rather than trying to code it myself but surprise surprise that was giving me issues too. I might just give up and use my own internals instead, I did buy an x27.168 stepper motor so I might just use that instead.

zoomkat

If you want to experiment, you might wire the tach up to 12v and check the input wire for voltage to ground with a multimeter. If there is no voltage on the input wire, then you might connect the arduino ground to the tach ground and an arduino digital pin to the tach input wire. Then try doing an analogWrite(digitalpin, 127) to the digital pin and see if you get a reading on the tach. Per the analogWrite reference page, various boards have pulse frequencies that range from 490hz to 1000hz.
Google forum search: Use Google Search box in upper right side of this page.
Why I like my 2005 Rio Yellow Honda S2000  https://www.youtube.com/watch?v=pWjMvrkUqX0

jremington

#12
Dec 26, 2019, 06:00 pm Last Edit: Dec 26, 2019, 06:01 pm by jremington
The tach might be expecting something other than a pulse from the "sensor".

I suggest to buy a tach that has already been reverse engineered, and demonstrated to work with an Arduino circuit.

ShaunJV12

If you want to experiment, you might wire the tach up to 12v and check the input wire for voltage to ground with a multimeter. If there is no voltage on the input wire, then you might connect the arduino ground to the tach ground and an arduino digital pin to the tach input wire. Then try doing an analogWrite(digitalpin, 127) to the digital pin and see if you get a reading on the tach. Per the analogWrite reference page, various boards have pulse frequencies that range from 490hz to 1000hz.
Not a bad idea, I'll give it a go. Thank you


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