Ignition Box If you have an ignition box i. If you have a low voltage V tachometer signal you can install a ohm "pull up" resister from the 12V gauge power wire ACC to the signal wire to increase the signal strength. Connect one end of the resister to the 12V ACC wire and the other end of the resister to the signal input wire. A ohm resister will work for signals in the 4V range. A higher value resister i. Due to the high voltage of the signal from the HEI you should use a tachometer filter to prevent damage to the tachometer.
Coil Pack or Individual Coils Distributorless Ignitions If you have a modern vehicle with "coil pack" or "individual ignition coils" distributorless igntion you will need a tach driver like the MSD to drive the tachometer. Troubleshooting If your tachometer has no signal or an erratic signal pointer jumping all over you first need to verify that you have correct power, ground and signal connections. Verify the gauge has 12V power.
The gauge should perform a self calibration check when turned on pointer moves to full scale, then back to zero. Verify you have a good common ground.
A bad ground connection is often the cause of many gauge issues. Make sure the gauge ground connection is connected directly to a good ground on the vehicle chassis.
We recommend using the same location as the battery negative terminal ground. Verify you are using a proper signal source. Verify you have a good signal that is at least 8V peak to peak in amplitude requires an oscilloscope.
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Some ECU signals are not strong enough to drive the tachometer. Try switching the signal input. Marshall tachometers come with 2 signal input options. Erratic Pointer Movement Verify correct signal and ground connections see above.
Verify your signal wire is not routed close to any high voltage sources i. The signal wire can pick up electrical interference signal noise if routed close to a high voltage source.
Marshall tachometers come with 2 signal input options, each input utilizes a different signal filter. Install a tachometer signal filter. Add a 10K Ohm resistor inline with the signal. Adding a resistor will increase the level of signal filtering. Try this on both signal inputs.
Use a higher ohm resistor for more filtering, a lower value ohm resistor for less filtering. Address, Phone, Fax Request Info. How do I hook up my tachometer? Standard Ignition Coil If you have a standard ignition coil you can use the negative terminal of the coil for the signal source. If you have a high output capacitive energy discharge type coil it is recommended that you install a tachometer filter to prevent damage to the tachometer. Design: BWE, Inc.My idea was to either use the signal from the wire between the ignition coil if thats the right name in the magneto and transformer before the sparkplug.
I tried the first option first. When the moped was running idle my OSC showed this about 60 hz signal with peaks of about V. Then I hooked up a voltage divider with k pot and a diode to filter out the spike going to the negative side. Because the voltage dropped when RPM got higher I left the pot so that the peaks in idle run were about 20V after the circuit.
Can I just connect this to to avr comparator or external interrupt pin and let the internal clamping diodes of the avr do their job? Do I still need to do some filtering in case of spikes or something?
Option 2 I wrapped some wire about 10 rounds I use to make connections on my breadboard around the sparkplug wire and tried to measure it with osc and nothing rational came out. How should I get a signal from that "coil"? Should it work by just putting the probe to the other end and the grounding to the other? Or do I need to connect the other end of the "coil" the the hull of the moped or how exatly should I do? I also looked up my options for calculating the prm. I first thought about collecting ignition pulses for a perioid of ms the calculating the rpm from that.
But after reading some threads about that I started to think about using the input capture. This chainsaw Thread has some discussion along these lines. I just dont know why im not getting a signal from that wire. It all sounds so simple in some of those threads discussing about the same stuff. What kind of wire do I need to have? Does the wire need to be wrapped around the other in some specific way? What am I not doing right. Quote: Should it work by just putting the probe to the other end and the grounding to the other?
Or do I need to connect the other end of the "coil" the the hull of the moped or how exactly should I do? Hardware stuff is fun. Hall sensor can do be a good option, since magneto field is quite strong - sensor can be mounted on magneto lid.
Perhaps read about air-core CT or Rogowski coil. You might find you need a few thousand or more turns. Might work however there are better ways. Still need to protect for transients.
Inexpensive timing lights have a clamp-on CT. You will still have to do some signal conditioning. I have one with installed BNC connector in housing. Have you read that postespecially the second suggestion about reading the charging system's low-voltage AC generator frequency, which is usually mounted directly on the crankshaft's left end?
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Arduino and Spark Plugs
My plan is to make RPM counter to my motorcycle. I'm planing to read ignition box signal with arduino. I think that ignition box gives V or I was wondering if I can read that signal with something like this:.
I found similar thing called Chippernut from the net. That device reads signal with PNP transistor. I circled a part where signal comes in. Does my design work at all with NPN transistor? And if it does can I have some advice with that transistor model and resistor sizes.
It have been while since last transistor calculations. Also is there any danger with coils recoil? As a general point if you are connecting to the same signal that goes to the ignition coil primary you will want to change your idea. The flyback pulses from the coil are high enough voltage that they can KILL most electronic circuits that you connect there - unless you really know what you are doing and how to properly clamp and filter the signal.
Your questions regarding the transistor would indicate that you may not be prepared to deal with that. Tap into that instead.
If you're not sure about the signal source, I would recommend you use an opto-isolator instead of a transistor. Same number of components and you will have full isolation from your arduino. Just size the resistor to provide the specified diode current, and your output for the emitter and collector part of the circuit is unchanged.
The emitter can even have a different, isolated ground than the signal source. Sign up to join this community. The best answers are voted up and rise to the top.
Home Questions Tags Users Unanswered. Asked 3 years, 10 months ago. Active 3 years, 10 months ago. Viewed 2k times. I was wondering if I can read that signal with something like this: I found similar thing called Chippernut from the net.
Schematic: Does my design work at all with NPN transistor? Active Oldest Votes. Michael Karas Michael Karas There was a RPM meter and it was hooked to the coil so I thought that it would work. Can I use voltage divider or op amp? A good start would be a series resistor from the coil connection point that then feeds to a zener diode clamp zener anode to GND. Put another resistor from the high side cathode of the zener to a capacitor to GND. A third resistor can then go from the top of the capacitor to the NPN transistor circuit.
John Birckhead John Birckhead 6, 1 1 gold badge 5 5 silver badges 20 20 bronze badges. Sign up or log in Sign up using Google.Pages:  2 3 4. Tachometer Project. I've been working on a tachometer project with a friend of mine for some time now. It's using a Mini Pro 5v 16mhz, serial seven segment display and a 24 Neopixel ring. Using this method the tachometer works flawlessly. It's nice and smooth when I turn the pot to increase the frequency.
On the vehicle I'm using the negative side of the ignition coil, piped into a Schmitt trigger. I also have a resistor, a capacitor, and a couple of diodes between that signal and the input of the optocoupler.
This issue I'm having is when the tach is connected to the negative side of the coil for the signal, the tach never stays as at a steady RPM, It pretty much just jumps all over the place. Yet when I go back to the frequency simulator, it's always nice and smooth.
Is there a typical way of doing this if the negative side of the ignition coil is used at the tach signal? Any help would be appreciated. JPG KrisKasprzak Sr. Re: Tachometer Project. Thanks, Kris. You don't say what engine you are working with, but if you are measuring period between pulses AND you are working with a V-6 for example at least the old Buick ones I hadthat is a V-8 with two cylinders left off as a result, the firing angle between cylinders is not uniform - short, long, short, long look at the cam in the distributor.
If you are just measuring the period and working with an engine like that, you will never get a stable reading.
You would have to count pulses for multiple revolutions of the engine for example then calculate RPM from that. It's a ci V8.
So, for example at 1 revolution of a V8 you get 4 pulses per revolution. The crankshaft to distributor ratio is You are correct.
My point was that if you had a V-6 and you did not specifythose engines give you 3 pulses per revolution, HOWEVER, they are not evenly spaced and if you are measuring the time between pulses, you will get two different times - one for the long pulse and the next one for a shorter pulse.
Something to be aware of if you ever work with a V6 that has the 90 degree "V" between cylinders.If we can't tunnel through the Earth, how do we know what's at its center? A lady introduce her husband's name with saying by which can stop or move train what is that name. Give points yo advocate thst biology is linked with physics chemistry mathsmatics geography. All Rights Reserved. The material on this site can not be reproduced, distributed, transmitted, cached or otherwise used, except with prior written permission of Multiply.
Hottest Questions. Previously Viewed. Unanswered Questions. Dashboard Lights and Gauges. Chevy Silverado. Plymouth Valiant. Wiki User You don't have to connect it to the coil. Under the driver's seat, they is a single slot which is used for timing by the mechanic, you can just connect it to it. As for power for the light, just go under the dash and spilt connect to one of the live wires. Asked in Dashboard Lights and Gauges Does the tachometer work off the coil?
It can also pull the signal from a spark wire. Asked in Chevy How do you hook up a hei distributor with external coil to a tachometer? The green wire from the tach goes to the negative side of the coil. Asked in Mitsubishi Trucks Where does tachometer wire hook to on mighty max ? It goes to the top wire on the coil, the one that usually has a cover over it. Asked in Acura Legend Why won't my 87 acura tachometer work and could it be affected by a bad ignition coil? A bad ignition coil can cause your Acura tachometer to quit working.
A bad tachometer cable or ground wire can also cause it to quit working. TRy on the neg side of the coil. Mounted to the drivers side strut tower. Connect the green wire to the negative side of the coil. Asked in Dodge Dakota How do you hook up a tachometer on a 98 dodge Dakota 3.
Since the truck is fuel injected, you will likely have to find a way to wire it in with the connector on the coil.This is by no means a robust solution or proper full-range RPM counter. Please be aware that this circuit could be made a lot simpler if you decide to power your Arduino direcly off of your bike's power supply 12 — 14V. In this case you will only need the voltage divider and none of the to-5V circuitry.
Not all Unos will like it so please do consult the manufacturer of your particular Uno to make sure you do not fry it! Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson.
The picture is more or less self-explanatory. The idea here is to regulate DC voltage generated by the bike's alternator around 12 — 14 volts down to a steady USB-friendly 5V and have this voltage on the breadboard's designated power rails. In addidtion to that I used a Ohm resistor and diode to provide visual indication of the board getting power. Here I used a Ohm resistor and a Ohm resistor; you can pick and choose your own values using any of the voltage divider calculators on the web.
Simply bear in mind that you should go for higher values to limit the current flow. We now make use of the power supply we set up in the previous step To make sure everything is working connect power-in using crocodile clips or bare wires to any voltage source providing 7 volts or more.
Load the attached file to your Arduino IDE, change pin assignments as required if you opted for other pins and upload the program to your Arduino. Possibly the hardest part and one I cannot help you much with. You need to find the signal wire that goes from ignition coil packs to tachometer on your bike.
A good way to make sure you got the right wire is disconnecting it and checking that RPM on tachometer go down to zero and upon touching this wire to its connetor RPM indicator goes alive again. Once you have the right wire turn off the engine, connect breadboard power-in to the bike's battery terminals, and attach RPM-in wire using a crocodile clip or twisting them together to the one you found above. Please make sure this connection is insulated from and does not touch any metal parts on the bike ground!
It may be that ignition coils on your bike send a signal every two strokes. You will see if this is the case immediately when you start the engine as RPM will be half of what they should be on idle. If this is the case you will need to modify the program to account for that. This is great, thanks for posting! As an experienced arduino user but newb with motorcycles, I like the idea of using familiar tools for troubleshooting.
Reply 4 years ago. Foreword This is by no means a robust solution or proper full-range RPM counter.Motorcycle digital carburetor synchronizer using Arduino & BME280, 3D printed idle screw knob
Before you start Please be aware that this circuit could be made a lot simpler if you decide to power your Arduino direcly off of your bike's power supply 12 — 14V. Add Teacher Note. Other than that: enjoy and have a good time doing what you needed and RPM counter for! Did you make this project? Share it with us!If your daily driver was born without a tach, fear not — a simple Arduino tachometer is well within your reach.
Eschewing the traditional analog meter display or even a digital readout, [deepsyx] opted to indicate shift points with four LEDs mounted to a scrap of old credit card. The high voltage signal from the coilpack passes on to the spark plug, which ignites the air-fuel mixture in that cylinder.
This is a good way to determine engine RPM without mechanical modifications to the car. Just make sure you modify the code for the correct number of cylinders in your vehicle. Simple, cheap, effective — even if it is more of a shift point indicator than true tachometer, it gets the job done. There is a huge tachometer right in the middle of the dash. It tells you the speed of the car. The instrument that is missing is the rev counter.
There is no way a company could sell a car without a tachometer. What you call a tachometer is called a speedometer, or speedo for short, elsewhere. The words tachometer and rev counter are used interchangably in this context.
Installing a Tachometer to a Coil
Most passenger vehicles since the 90s get the speed from the vehicle speed sensor, which measures wheel speed and not engine speed. Are you sure? Different kind of speedo though :. That is usually refered to as a speedometer I believe. Tachometer or tach gauge is the correct name for an instrument indicating the number of revolutions per time period.
Strictly speaking a rev counter would just count the number of revolutions made. All tachometers measure the speed of something. A rev counter measures the engine speed, and the speedometer measures the wheel speed. You see your RPM on a tacho connected to the motor and your speed on a tacho connected to you wheels gearbox output shaft. You can easily use blue LEDs on the dashboard.
One time I tested an LED and wondered, why it was only slightly glowing — the connection went through my finger. Further tests showed, that even with nA a faint glow was visible normal daylight, no sun, made shadow with hand.
Because it did frequency to voltage conversion diode resistor capacitor it had to calibrated with a pot. The vibrations of the bike destroyed the pot.
So it was a FAIL lol, but interesting while it worked because it was quite unique at that time. Nice work!