Oh, and put protection diodes across Q1 & Q2! (for Q1, cathode towards +Vmotor; for Q2, anode towards -Vmotor). And experiment with the resistor values as needed. Rich Sulin wrote: > > We Gates Herr Holger, > > Holger Metschulat wrote: > > > Hi, > > > > I want to build a bidirectional motor control for a DC motor with one pin > > connected to GND, so I need a dual power supply (+/-Uo). How can I control > > this motor using only 2 digital (+5V/0V) lines (enable/disable and > > forward/backward)? > > > > -- > > Gruss * Holger Metschulat > > Holger * e-mail: homer@sgs.wh.tu-darmstadt.de > > * "http://www.sgs.wh.tu-darmstadt.de/homer" > > ** "Verstaerker schwingen immer, Oszillatoren nie!" (Murphy) ** > > How about this: > +Vmotor > | > / > |/ > FORWARD-------[R1]----+---[R3]---+--| Q1 > | |K |\> > -5V---[R5]----+ [D1] | > 1+---+6 | |A | > DISABLE--[R2]--+ +--+--+ GND--+ +----[D.C. MOTOR]--+ > 2|OC1| | |K | | > +--+ +--+ | [D2] | | > | +---+8 | | |A | GND > | | | | |/> > GND GND +-[R4]--+--| Q2 > |\ > \ > | > -Vmotor > > Where Q1=NPN darlington power, e.g. D40K2; Q2=PNP darlington power, e.g. D41K2; OC1=Optocoupler H11F1; R1=1k; R2=180; R3=2k; R4=1k; R5=2k; D1=D2=1N4148. > > But really, it would be nicer not to have one end of the motor grounded, so you could use existing H-bridge driver ICs. > -- > +----------------------------------------- > | Richard Sulin > | > | Please remove the anti-spam stars in > | my e-mail address in order to reply. > | > | thus: richs <at> dcdu <dot> com > +----------------------------------------- -- +----------------------------------------- | Richard Sulin | | Please remove the anti-spam stars in | my e-mail address in order to reply. | | thus: richs <at> dcdu <dot> com +-----------------------------------------
Date: Wed, 2 Dec 1998 17:15:14 GMT
Original Subject: Re: DC motor control