small robot help-urgent

[aruna1]

guys I'm making a tiny line follower robot. it is a basic line following with two transistors.I use two pager motors and rubber wheel on cassette players as wheels.my question is this robot it too fast therefor it cant respond to line accordingly. there is no motor speed control mechanism implemented.can some one please tell me how to slow this down without making a big circuit?
a transistor based pwm circuit will be great i guess.I'm posting the circuit I'm using

I'm in hurry as I'm making this for an exibition and date is getting closer

thank you

[Soeren]

Hi,

my question is this robot it too fast therefor it cant respond to line accordingly. there is no motor speed control mechanism implemented.can some one please tell me how to slow this down without making a big circuit?
a transistor based pwm circuit will be great i guess.I'm posting the circuit I'm using

A diode (or more) in series with the motor(s) should help. A resistor in series with the motor(s) would work too.

I'm in hurry as I'm making this for an exibition and date is getting closer

Aren't you always? 
Why on earth don't you start a little earlier?

[aruna1]

well sorry for urgency.they always asked me to built them at the last moment, and with this academic load its really hard to allocaate time for robots 

by the way can you suggest me a small h bridge ic that contains 2 full bridges in 8 pin package?
thank you

[cyberfish]

Can I get an 1 pin AND gate?

1 full bridge requires 4 inputs. 2 requires 8.

Where does power come from?

[Soeren]

Hi,

by the way can you suggest me a small h bridge ic that contains 2 full bridges in 8 pin package?

Nobody can.
2 full bridges takes (at least): 4 inputs, 4 outputs and 2 power lines.
I don't know of a 10 pin device either and since you didn't mention what voltage and current you need, I cannot point you to anything at all.

[aruna1]

oh, i use 3.6v nimh battery and current is about 90mA per each motor

[blackbeard]

Hi,

by the way can you suggest me a small h bridge ic that contains 2 full bridges in 8 pin package?

Nobody can.
2 full bridges takes (at least): 4 inputs, 4 outputs and 2 power lines.
I don't know of a 10 pin device either and since you didn't mention what voltage and current you need, I cannot point you to anything at all.

actually the l293d is a quad half H bridge IC in an 8 pin package. it's actually pretty good and it can control 2 motors independently

edit: DOH >.< i was thinking 16

[aruna1]

Hi,

by the way can you suggest me a small h bridge ic that contains 2 full bridges in 8 pin package?

Nobody can.
2 full bridges takes (at least): 4 inputs, 4 outputs and 2 power lines.
I don't know of a 10 pin device either and since you didn't mention what voltage and current you need, I cannot point you to anything at all.

nope it has 14 pins

actually the l293d is a quad half H bridge IC in an 8 pin package. it's actually pretty good and it can control 2 motors independently

[knossos]

guys I'm making a tiny line follower robot. it is a basic line following with two transistors.I use two pager motors and rubber wheel on cassette players as wheels.my question is this robot it too fast therefor it cant respond to line accordingly. there is no motor speed control mechanism implemented.can some one please tell me how to slow this down without making a big circuit?

Well, a simple way would be smaller wheels.  Not sure how small your line follower is, but a great idea for small wheels can be found on some of the beetle bots.  Use the motor shaft itself as the wheel, you can even put some heat shrink on it for more traction.  Also changing the angle of the motor will change speed of the robot: the closer the motors are to being parallel to the ground, the faster the robot goes.

I'm in hurry as I'm making this for an exibition and date is getting closer

Hope this doesn't come too late.  I'm curious to hear what solution you used.