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Need an idea on calculating motor speed...!

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Greatbuddy

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Hello dear friends,
Iam here with new prob,
Well i have decided a motor and i need to regulate the speed of the DC motor and display the speed of it.

Hmm may be for u its a silly thing, but its a golden idea for me from ur side.

Please do not comment on my posts iam hurted here much, But i cant get probe solutions in anywhere except here.

Thanks to all.

Waiting for ur golden ideas and designs.
 
I forgot one more thing that i must need the display too, I mean what kind display i should use and it must be visible in day-light too.

Sorry friends but please clarify my small doubts..

Hope i wont see any -ve responses..
 
Is there anyway to regulate the speed of DC motor and alternatively i have to monitor the speed?

I mean to say is i want to regulate the speed of Dc motor and at the sametime i want to dispaly the speed too.
 
Is there any simple circuit other than Tachometer??

Since the dimensions may vary for my requirement..

hi,
Stick a small reflective patch on the motor shaft.
Use a LED emitter/detector pair, detect each rotation of the shaft.

Either use a counter/display driver ic or a PIC to count and display to a LCD/LED.

If you want to control the speed of the motor use a PIC and drive the motor with PWM via a HBridge.
 
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Can u eloborate ur idea in the form of circuit? @ericgibbs

The IR emitter/detector pair are mounted in a small moulded housing.
The emitter and detector are aligned so that the emitter beam is only seen by the detector when a reflective surface is in front of both of them.

I'll try to find an image I can post.:)

EDIT:
This is one example of an opto reflector.
 

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Thank u ericgibbs

hi,
Depending upon the motor shaft dimensions it is possible to fix more that one reflector to the shaft, say at 90deg points on the shaft, this would improve the resolution at lower shaft speeds.
 
Hi,
First try to understand what he is telling!. You will be getting a pulse of reflected beam for each rotation. This series of pulses you have to feed into the input of a counter circuit and and then output it to a seven segment display.
 
RPM is armature voltage divided by rated voltage times rated rated no load RPM, (nameplate rating is full load)

Armature voltage is supply voltage times duty cycle minus armature current times armature resistance

All this analog crap makes it great for control but relatively lousy for absolute accuracy

Dan
 
Is there anyway to regulate the speed of DC motor and alternatively i have to monitor the speed?

Yes, but I don't have a link.
The thing alternately powered the motor and then gauged back EMF due to the motor speed.
Depending on motor shaft inertia this was probably done at 20 Hz or 200 Hz or 1 Hz.
 
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