View Full Version : power supply problem for 12 v motor

03-04-2008, 11:06 PM
hey ppl my problem is that i have got 2 12 v motors with 300 mA draw iam using l293d for motor control but iaam in a fix what kind of power supply to use i used 2 9 v battery in series and regulated it at 12v using an IC but the motors draw too much power so i gave it up so can u ppl help me by telling what kinda power supply i should use for the motors and also if i use ac and step it dow to 12v and then use bridge rectfier then can u plzz give the circuit

any kinda help is much appreciated

03-05-2008, 11:27 AM

9V batteries are useless for any kind of work.They cannot provide continuous current in the excess of 100mA. There are two solutions to your problem :

1) If your bot is autonomous bot then : you can use 9V(180mAh) rechargeable cell. It costs 220Rs. You can very well run ur motors at 9V, only they will run at a bit less speed.

2)If your bot is not autonomous then you have to go for other power supply. you can make your own power supply easily ... see this :

3)If you don't want that headache ... you can use computer's AT SMPS (note the word AT ) . You can get this 2nd hand SMPS at just Rs 100to150 and it can provide large current . It will give you regulated 12V and 5V outputs. You can also use ATX SMPS, but then you have to make a small arrangement to give it starting pulse so that SMPS gets powered up (search google for this)

03-05-2008, 10:29 PM
there is a good instructable to hack computer power supply.
have a look at instructables.com