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Topic: Reading pulses through Inductive Clamp  (Read 6220 times) previous topic - next topic

TomGeorge

#15
Aug 24, 2018, 06:31 am Last Edit: Aug 24, 2018, 06:32 am by TomGeorge
Not always. Some older engines fire on the compression stroke as well. Before you say phooey, I know because I have one. The pre-made tachometer reads 2X the actual RPM.
When emission requirements and ECU were getting into serious operation, the distributor was omitted and a spark coil for each cylinder was adapted, but some manufactures for say a 6cyl 4stroke engine, used three spark coils.
Each of the coils was/is connected to the two cylinders that are mechanically in phase but 4stroke wise 180deg out of phase.

So when the coil fired, one cylinder was about to go to top of compression, the other was about to go to the top of exhaust.

So you basically had 2stroke ignition on a 4stroke motor.

Most engines these days use one coil per cylinder.
Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

6v6gt

Not always. Some older engines fire on the compression stroke as well. Before you say phooey, I know because I have one. The pre-made tachometer reads 2X the actual RPM.
Phooey ? Certainly not from me. Read the end of post #10.

allanhurst

The current flowing in a spark lead is oscilliatory - several pulses of alternating polarity can flow over a few uS. The thyristor/555 cleans this up.  Nice idea..

I've measured one of those clamp-on inductive pickups - a couple of hundred ohms. So quite a few turns.


Allan

JoeNova

Guys, its a 4 stroke single cylinder engine. No wasted spark. One spark every 2 RPMs.
I'm not new to this, I build race cars and am picking up small cart/bike engines as a hobby.

I just need a way to measure RPM via inductive clamp. Don't dig into it too much.

Paul_KD7HB

The current flowing in a spark lead is oscilliatory - several pulses of alternating polarity can flow over a few uS. The thyristor/555 cleans this up.  Nice idea..

I've measured one of those clamp-on inductive pickups - a couple of hundred ohms. So quite a few turns.


Allan
Thanks!
Paul

Hexen

#20
Sep 04, 2018, 06:40 am Last Edit: Sep 04, 2018, 06:55 am by Hexen
I may go a different route. The circuit looks just slightly too complicated for me. I tried to get a quote on a small PCB with the components I need and it was more than it would be to go buy one of the expensive ones that are already complete.

I may go back to using a proximity sensor to read teeth on a sprocket and just coming up with a clever way to slide the sensor when the sprocket is changed out for a different diameter.

I've also been looking into something like this to detect the teeth on the sprocket:
https://www.banggood.com/Speed-Measuring-Sensor-Counter-Motor-Test-Groove-Coupler-Module-p-947284.html?gmcCountry=US&currency=USD&createTmp=1&cur_warehouse=CN&utm_source=googleshopping&utm_medium=cpc_elc&utm_content=frank&utm_campaign=pla-ele-diy-us-pc-0516&gclid=CjwKCAjwt7PcBRBbEiwAfwfVGKwY-ZMz-bQwPr_8wljjXeQGDdMTU6MxhYkyoNG7UXOzSMPbDpc5xRoCHZUQAvD_BwE

The only issue is, will it be able to accurately detect 2000 teeth per second?

TomGeorge

#21
Sep 04, 2018, 10:47 am Last Edit: Sep 04, 2018, 10:49 am by TomGeorge
Hi,
You don't need a PCB made.
Use vero/proto board of one sort or another;



Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

6v6gt

. . . and you can duplicate the (one shot) functionality of the 555 timer in software reducing the component count further.

Hexen

Is there perhaps an easier way to do this?

I've searched this particular subject for weeks and never found ONE clear answer as to how other than the diagram I posted.

Someone mentioned just finding a way to clamp the voltage down to 5v or less and pinning it into a digital port and measuring the time between the input going HIGH.

JDBlaine

I'm in the boat with ya, Hexen...I've read over a thousand posts, and gotten two thousand different answers...

I'm fairly good with electronics (although never dove into induction), and can build a weather station that'll make a sailor blush...lol....

One buddy says NO to going direct from the inductor to a pin, another says it's fine...

Ok guys...we really appreciate the help, and in depth discussion...I've learned a lot from it...but can get just a basic answer...Motorcycle Dyno, Arduino control board, inductive pickup.

I'm going with the schematic from page 1, Post #5...Your own post, Hexen.  =-)

ranjith_asp

I'm in the boat with ya, Hexen...I've read over a thousand posts, and gotten two thousand different answers...

I'm fairly good with electronics (although never dove into induction), and can build a weather station that'll make a sailor blush...lol....

One buddy says NO to going direct from the inductor to a pin, another says it's fine...

Ok guys...we really appreciate the help, and in depth discussion...I've learned a lot from it...but can get just a basic answer...Motorcycle Dyno, Arduino control board, inductive pickup.

I'm going with the schematic from page 1, Post #5...Your own post, Hexen.  =-)
Any updates Hexen & JDBlaine??

I have a clamp and Uno with me, and wan to connect and log the RPM data in PC. The engine is a single cylinder 4 stroke bike. Suggestions to add a over-voltage protection to the in-pin would be much appreciated.

_Ranjith

PS: As you might already know, the spark is initiated by a single tooth circular plate and a pickup sensor (so one spark initiation per rotation of this single tooth plate) mounted inside the transmission box - all part of the bike itself. :)

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