how to control speed of a small dc motor used in cd player

[rajaram04]

hmm i see the info is again shaking the nerves in mind , yess im doing beginner's cause we generally do not follow it & in case waste a lot of money & time with more impacts on brain so better to understand the basics n to make of own in low budjets
thanks a lot sir

 

[D.A.(Tony)Stewart]

Sir may i know about the problems facing by science in the field of A.I. (Artificial Intellegence) ?

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Function: to rotate a disc contaning electronics producing infra red & electromagnetic waves

THe problem with AI is how to quantify HI or human intelligence. Fuzzy Logic with auto-learning methods are best with limits on each variable. My wife's dear departed brother in-law Carlo Lucas was a world expert in this area. It can be applied to any aspect of life, from real-estate, banking, and even auto-focus as used by Sony in low light levels.

Can you expand on Function Spec please.
Function: to rotate a disc contaning electronics producing infra red & electromagnetic waves
Is this intended to be a and time & frequency multiplexed transmitter for visual or communication effects?
Define the interface input and output and desired process control.

I would get a free CD player and modify to be an open spindle and use 3 axis accelerometer or piezo ceramic caps to measure vibration for tuning the balance and mounted the components on a CD or better a large optical disk player ( now extinct ) which has both constant rotational and constant linear velocity control.

Then borrow a scope and monitor all the signals that are show important correlation to motor drive and make a journal. THen you can share these with others such as us to hep you understand.. Any chip P/N's ought to be listed in a Bill of Material around the motor signals.

Otherwise designing from scratch may work with a cookbook design, but depends on your experience making things work.


You can also consider a HDD spindle motor controller by gutting a really old 5.25 Disk drive that spins at 3600 RPM or higher. They usually had a dedicated servo surface so when you remove the heads and feedback , the motor may shut down from MPU control. But if you scope the interface signals and duplicate them with MOSFET drivers, you can create a spinning disk with mirror metallic cobalt doped magnetic media platter to reflect your laser Light or put on a torroidal choke in the center and drive the LED's or EM emitters wirelessly with a similar large circular sending coil near the center of the platter and rectify for DC. Balance is key but you can transfer several watts easily using large 3~5cm diam, coils running < 1MHz in a resonant tuned ccct.

 

[rajaram04]

sir thanks a lot to get me info about A.I. cause im too doing reasearch on A.I. i did too many studies a lot of work n the prblm u r telling can be solved i found it so & i ll do more study after ur explanation thans a lit once again.
Sir i want to let khow about the feature relating my experiment is that it dont have any relation btwn rotation & the circuitry in the disc it is rotating , it is totally another matter actually i just want to operate the speed by using simple crcuitry as it would be applied to many of my projct wrk not only this one sir . i want to clear it that im going through a very vast designing & experiment & it has nothing to do with the speed controller as it is just a 1% part of the total 10 years work . please let me know about any of that .
one person helped me a lot lot lot & now im searching the substitute for the components he described & u my see above in the past post . thats the matter

 

[ard]

a substitute for IRFZ46N

You could get away using any NPN transistor instead. Get rid of R2 and introduce a resistor of about 1 K in between pin 7 of the 555 and the base of the transistor. Also, a reverse biased diode across the motor might be a good idea.

 

[rajaram04]

ohh dats nice sir hmmm thanks for it but now the prblm im having here dat im using bc548 simply but its get heated too much enough to make small burn on bare fingers should i use metal cap transistors like 2222 , 2646 ? please comment & thanks a lot

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please also tell me what's the motive of the diode in reverse bias accross motor ????

 

[ard]

What voltage are you using to drive the motor? Since you're using a cdrom tray motor, I'm assuming it is less than 5 volts.

Try increasing the bias reistor to 4.7k.

The reverse diode is to protect the transistor from negative voltages created across an inductive load (your motor) during the switching.

 

[rajaram04]

sir strictly speaking the circuit you shown me is a complete failure i did it with 6v then 9v n didn't observe a single effect on the speed of motor ,
Applying all the changes we discussed here i ve no result , here is the circuit diagram below :-
**broken link removed**