Hi Paul, Looking at the circuit I can not see why it shouldn't work. You need to build it and check a few things. 5V is near the minimum operating voltage for the L293 hence you must insure that the voltage supply to the motor does not come to close to 4.5V, your SMPS chip as a +- 2.5% accuracy which means the voltage can be from 4.875V to 5.125V, so normally it should be ok. I know you measured the current on the motor but that would be the main concern. When you start the motor or change direction the current can be very high, hence you need to check this again when you build your circuit, to make sure the voltage does not drop too much. I would suggest that you do not use PWM to start with, just turn the motor on and off by sending a 0 or 1 to the port pins, as required, when you get that working then you can think about PWM. Good luck. Best Regards Luis -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of Paul Chany Sent: 13 January 2010 21:47 To: piclist@mit.edu Subject: Re: [PIC][TECH] Brushed DC Motor Application:BidirectionalSpeedController - Is the schematic good? Hi Luis, "Moreira, Luis A" writes: > Your circuit will not work because if you look at the datasheet for > the L293 it says the control is TTL and also when you look at the > min Vs it says it can not be lower than Vss which is 4.5V minimum. > Best Regards > Luis I edited the circuit following Your advices and here it is: http://csanyi-pal.info/album/index.php/image/view/2 or here: http://i520.photobucket.com/albums/w327/csanyipal/Bi-direct-Speed_DC_Mot orControll.jpg Is it OK now? -- Regards, Paul Chany You can freely correct me in my English. http://csanyi-pal.info -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist