# How to complete or regenerate missing pulse?

#### andreas2019

Joined Jul 22, 2019
4
This pulse generate from motorcycle pickup coil. They are 9 pulse and 3 empty pulse in 1 time flywheel rotation. I want complete the pulse to 12 like this picture. What can I do to solve this problem?

#### cmartinez

Joined Jan 17, 2007
6,877
How much do you know about electronics? Also, why do you want to complete the pulse train? Are you trying to build a tachometer or something similar?

#### WBahn

Joined Mar 31, 2012
25,546
There are a number of ways to accomplish it, depending one what resources you have available and what your specific objectives and requirements are.

The easiest would be to use a small microcontroller. Have one pin on the micro detect the pulses from the tach and calculate the average time between pulses based on measuring the time between nine pulses and dividing the result by 12. Then use that time as a control value to generate a stream of pulses on another pin. Adjust the frequency and amount by which you adjust the control value to get the responsiveness you need.

#### Alec_t

Joined Sep 17, 2013
11,123
Aren't the missing pulses intentional, for shaft position sensing?
Why do you want to fill in the gaps? If you really need to, then use of a microcontroller would arguably be the simplest solution.

#### andreas2019

Joined Jul 22, 2019
4
Are you trying to build a tachometer or something similar?
yes, something like this.

#### cmartinez

Joined Jan 17, 2007
6,877
yes, something like this.
In that case, there are other approaches you could try. As has already been mentioned, using an MCU would probably be the easiest one. But you haven't answered my question on how knowledgeable you are in electronics.

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#### WBahn

Joined Mar 31, 2012
25,546
Are you trying to build a tachometer or something similar?
yes, something like this.
If it's ENOUGH like a tachometer (the devil's in the details) then you don't need to fill in the missing pulses. You have a system that produces nine pulses per revolution. The fact that they aren't evenly spaced is probably irrelevant.

Joined Mar 10, 2018
4,057
You have to establish criteria for what constitutes a missing pulse.

Is it 1,2, 3...n missing pulses that you have to correct for ?

One method is ignore the missing pulse, if infrequent, by using integration
or a peak detector in the output display process. If the tach is a d'arsonval
movement it inherently integrates, to a point, because of mechanical inertia.
But if electronic display you have to eliminate jitter in display if you are trying
to handle frequent random missing pulses. One way a simple period counter
that says N consecutive pulses that meet a value (with some allowed deviation)
are the "model pulse train" and look for a deviant pulse in the continuous train
and not display it. Simply ignore it.

I think some simple code and a period counter a a PWM to regen the signal
could perform this.

Another method is attach to crank another pulse generator, optical or magnetic,
and compare streams from ignition and crank.

Regards, Dana.