hello and new to the forum :]

[CharlieCR]

hello there, been interested in electronics for a while and thought i might aswell dive in,
first project is a voltage devider i beilive its called,
but nevermind about that i wonderd if anybody could help me whith this ( into old scooters, (vespa) so this is were this question comes from)

wanted to know if it was possible to make somthing that can count the number of electrical pulses that passes through it per second then can times it by 60...
(honestly dont have a clue how electronics work much - willing to learn though)
basicly wating to do a revometer or spedometer that has the ability to go up to 10,000 revs,

the way i think it will work is, the scooter makes a spark which sends an electronic signal up to the system (1 spark = 1 rotation = 1 electrical pulse up to the bulb)), want it to be able to counnt the number of sparks per second then times it by 60 (so it is not stuck at certain revvs for a muinite ), scooter is 12v so probs can be run from ligh bulb wire, wanting to do this for Dyno reasons ...

dont know what over info needs to be provided...

all help would be much ... erm.... help
cheers

 

[CharlieCR]

a pulse counter or somthing might be the word im looking for,

 

[Reloadron]

What you seem to be looking for is a tachometer. A display of sorts that will provide the engine speed in RPM (Revolutions Per Min). There are several ways to go about it but it all begins with a sensor to pick up when the plug fires. I am not at all familiar with Vespa scooters (or any scooters) for that matter. I assume 1 cylinder? Any information you may have on the ignition system would help. We have had plenty of threads here as to motorcycle and automotive tachometer applications.

Welcome to the Forums!

Ron

 

[CharlieCR]

ok my other post hasnt come through yet, ??
but ive read a little more on the subject in i see im going to need a 555 pulds oscilator thing, need 5v to run it
and need a display board (of coarse that will be the last on the list) - it cannot be on of those optical reflector tachometer things, has to do it by the oscillating power , run the display whit a battery and all other compoment mainly... so thats as far as it is so far, dont know about capacitors and that much , know how they work and that but not know were put them,
looking for a schamitic maybe?

https://www.electro-tech-online.com/custompdfs/2011/02/PK_12V_6pole_no_batt.pdf
that is the wiring daigram for the electronics if anybody would be kind anough to help me come up with something, (obv i will try my best and will need to ask alot of qeutions as this will pretty much be a first project, mabye it will be to ambitious?? )

 

[CharlieCR]

so after a bt more looking around i think a Hall Sencor wll do the job measuring the electic current comng to or from the spark plug - count the freaqency imbatween per and times by 60, geussing though t will still need a micropressesor to be able to measure it and display it on an LCD..-has any body seen a scamatic whit this type of thing on - or could help myself produce one mabye?
cheers

 

[Reloadron]

The first problem you face is this scooter does not use a battery at all and is a totally AC electrical system. It looks like they take AC off the alternator and then use a shunt regulator to keep it down around 12 volts. The electronic ignition module gets what likely is a timing signal off the stator of the alternator to fire the spark plug. That would be my guess anyway.

Whatever you use you will need a power source for it. Possibly rectify and filter the regulated AC? I am not sure. You could likely just wrap several turns of wire around the spark plug cable as a signal pickup and then condition it. From there a programmed PIC chip interfaced to a display may be a solution to display RPM.

Doesn't anyone make a after market tachometer for these things?

Ron

 

[CharlieCR]

£80 is cheapest one ive seen and it isnt to cracking - (and get to learn something in the process )
will a 9V battery do the job mabye to power the system?? - the best way to sounds like wrapping wrapping some copper wire round it and takin it to a Programmed PC chip mabye then.

mabye it would be an idea to have 2 moters attatched to a shaft by some pu;lly that fight against each other , then as the revvs pick up the moter could pull the needle (attatched to the shaft) to one way showng an increase in Revvs, althought i predict there would be some hard callibration involved?

 

[CharlieCR]

here mabye this could be ov some value?
https://www.electro-tech-online.com/custompdfs/2011/02/794208.pdf