hmm.. should i use 2n2222 and 2n2907..??
ill buy a DC motor maybe tommorow. 6v DC motor right??
Yes, try those transistors.
And look for a lower current motor, similar to the pololu one I linked to above. Stall current of around 800mA, etc.
Hey, I'm glad it's working ok.
Regarding the motors, I was checking out the twin-gearbox specs over here:
The motors appear to be low voltage (3 - 6 volts) but draw a fair whack of current, certainly more than the 3904/3906 can handle. Check the specs in the Mabuchi motors pdf, referenced on the same page.
I think you'll need to beef up the transistors in your h-bridge.
You could also look at swapping out the high current motors in the gearbox with something like this:
Used to be able to buy a similar motor called a P9000. Maybe check your local electronics suppliers for motor with specs approximately that of the pololu motor.
Yes. Use a trimmer. But, where is P2? There should only be P1, used to adjust the voltage at pin 2 of the LM393.
edited: It's official - I'm an idiot. P2 is the pot for the second sensor! Duh.
You could add a visual indicator to show when the sensor is triggered:
D3 just stops the LED/resistor combination from affectting the delay time.