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Gearloose
06-24-2004, 07:21 AM
How does one "calm down" overactive small DC motors (without using a proper motor controller)? Can one just use resistors? And...ah...if so...where do they go? I'm new to all this. I've got two motors that have a little too much speed than is needed. I want to slow them down (without the use of gears).

vikas
06-24-2004, 05:13 PM
Dont use resistors ( it will lead to lots of wastage of battery ) Use a simple power trasistor ( 2n3055 ) and bias it accordigly to allw the motor control to be easily done though a 10 k resistor ( that should be easy )

rao
06-24-2004, 11:07 PM
a resistor will eat up power....

what about a simple PWM generator??

you know Pulse width modulator ckt..

I can get you the simplified ckt.. if you wanna

I am saying this as if you control the input.. there wont be any need for lossful components like a resistor..


What say vikas ?

Rao

happy_99
06-26-2004, 12:34 AM
PWM is great! Can be made using cheap timer ICs like 555.

Regds

Sunil

rao
06-26-2004, 10:34 AM
yeah!!

thats what I was talkin about!!
555 can be easily modified to make a PWM generator...

just make a monostable multivibrator out of it...

Rao

sri
06-26-2004, 11:59 AM
i dont think 555 can source ehough,depends what he means by small motors

after the 555 u can use:
us esc1815 or sl100 for puto .8-1 amps

or mosfets for anything higher......th eones used in inverters can source genrally upto 2amps

but i dont tink u want that much ....... "small motor" ........u said?

by the way it is possible that u generate perfect sq waves from the p.generator. but the signal breaks up as soon u feed it to the motor....in that case attach a capacitor in II ... u ll have to experiment a bit with the
values though........

sumandeep1984
10-05-2004, 08:47 AM
555 can't source more than a few mA of current but is a real nice PWM generator

A simple H-Bridge can be connected to the output, it will add nice direction control if needed. Or even half of the h-bridge (using 1 npn & 1 pnp power transistor) can be wired, if direction control is not needed

rajiv
05-24-2005, 11:22 AM
i suggest u to use irf840 which is a n-channelMOSFET capable iof driving abt 8a(continous) & 32a(pulsed) current thru it. u an connect this to o/p of 555 which which ll produce the necessary pwm o/p. for bidirectional rotation u can form a bridge n/w. moreover u don't need to use fwd's since they are already inside the mosfet's.

rajiv
05-24-2005, 11:23 AM
i suggest u to use irf840 which is a n-channelMOSFET capable iof driving abt 8a(continous) & 32a(pulsed) current thru it. u an connect this to o/p of 555 which which ll produce the necessary pwm o/p. for bidirectional rotation u can form a bridge n/w. moreover u don't need to use fwd's since they are already inside the mosfet's. i have used these mos in my stepper drive prj. i works fine with all kinds of pulsed o/p.it is specially designed for this purpose.

tanish
05-28-2005, 01:57 PM
hello
8)

addy
01-01-2006, 07:22 PM
do pwm using mic....
they r d best.....
u can use irfz44n....
it can bear really high current.