pwm using 555 for a newbie

[sharkpandi]

I just wanted to make my first toy car....So i wanted to use a pwm to controll the speed,and to turn left,right.

http://www.circuitlake.com/simple-pw...on-ic-555.html


This is the circuit which i was referring for making my car as i feel that its the most easiest ckt bcos of its components.

The problem i found was that the discharge pin (7) was left open....I knew that discharge pin is used to discharge the inbuilt capacitor,in this case it is left open.May i know how to make it complete.

And one more dbt....

I have the transistor BC 547 instead of TIP 31,Will the transistor be compatible with the ckt....i found that the collector current of bc 547 is 100mA,for TIP 31 it is 3A.

[newInRobotics]

Your link does not work.

[billhowl]

Is this the link you referring
http://www.circuitlake.com/simple-pwm-controller-based-on-ic-555.html

the circuit was design to discharge capacitor through output pin, so is okay for pin 7 open.

If your motors will take less then 100mA, then you can use the transistor BC 547 instead of TIP 31.

[Soeren]

Hi,

http://www.circuitlake.com/simple-pw...on-ic-555.html

Here's the working link:
http://www.circuitlake.com/simple-pwm-controller-based-on-ic-555.html

Always check the links you post by using "Preview" -> Right click link -> open in new tab/window.

[...] ckt bcos [...]

Please write plain English, you're not texting one of your bro's.

The problem i found was that the discharge pin (7) was left open....I knew that discharge pin is used to discharge the inbuilt capacitor,in this case it is left open.May i know how to make it complete.

Know how what?
The discharge output is not used in this circuit.
The capacitor is discharged through R1, VR1 and D1 when the output (pin 3) is low and charged through R1, VR1 and D2 when the output is high.

And one more dbt....

Since you obviously don't mean "Dialectical Behavior Therapy", please buy some vowels, they're not that expensive

I have the transistor BC 547 instead of TIP 31,Will the transistor be compatible with the ckt....i found that the collector current of bc 547 is 100mA,for TIP 31 it is 3A.

You answer that one yourself. The BC547 won't be able to handle the current of a motor and it would be a serious down grade, as the 555 in itself handles 200mA.
For testing whether the rest of the circuit works, you can substitute the motor with a LED (in series with a 1k resistor!).

Never ever ever ever substitute components in circuits you find, unless you know 100% what you're doing.

[Soeren]

Hi,

If your motors will take less then 100mA, then you can use the transistor BC 547 instead of TIP 31.

If the motors takes less than 100mA, there's no need for a transistor at all.

[sharkpandi]

Thanks for the information people.I'll try to find the alternative for the components.