DC Motor Speed Control !!!

Hi there every one !!

first, i am a beginer in electronics in the university, and i had designed a circuit , that may work - because it is a switching circuit, when there is a 5 volts input over transistor base - the transistor switches on and the motor works, when ot changes to 0 volts the transistor cuts off so the motor stops working with a deaccelerating motion till the other 5 volts input comes in to accelerat it again - this means when you put a high frequency the moto speeds up, when thes is a low frequency the motos e accelerates, you can use a 555 timer to give you the wanted frequency

" i dont thing that i am right "

but hope avery one comments me about it - and thank you
here is the scemetic

The 555 timer was designed to output a frequency, not do Pulse Width Modulation. I suppose you could do it by altering the voltage applied to pin 5 which does change the pulse width of the signal.

EDIT: Congrats on your 1st post!

Actually you can do PWM with a 555 timer. Its pretty well documented if you search for it on google. Here is just one link:

http://www.cpemma.co.uk/pwm.html

Check out Nomad's 555 circuit about 3/4 of the way down. The first circuit uses OP Amps to generate PWM.

-Bill

There is a Very Simple, Good circuit on my site to do what you want.
It uses a 555 and one or more Mos-Fets.
**broken link removed**

Look at the PWM control

Take care.......Gary