On Fri, 2008-08-01 at 13:51 -0500, Chris Radek wrote: > On Fri, Aug 01, 2008 at 02:14:07PM -0400, Sergey Izvoztchikov wrote: > > > - Servo motor drivers - 3 x $19 > > http://www.solarbotics.com/products/k_cmd/ > > Each L298 has two H-bridges. I run both servos on my little lathe > with one L298 package.
I read that you can parallel each section to get 4 Amps. 2 Amps can run your lathe? What voltage? > The L298 does not have current limiting built in. I have not had > any trouble with mine though. I was not sure it would last. The datasheet: http://www.stmicroelectronics.com/stonline/products/literature/ds/1773/l298.pdf has very little information on the current limit. It shows a circuit going back to the midsection of the triangular op-amp comparator symbol. I suppose that indicates something. It is also stated that the voltage range on the pin is -1 to +2 Volts. I am guessing that you size the resistor to ground such that 2V / I-limit = R ? Oops, I just saw the internal schematic that shows the I sense pin is the output bridge ground, so all of the motor current goes through this pin. The wattage for the resistor will be an issue too. I am guessing the bottom output transistor will conduct if there is a .6 Base-Emitter voltage. If the AND gate outputs 2.6 Volts, then the bottom transistor will start to shut down at 2 Volts? I thought that FET's could, but transistors could not be paralleled for increasing output current. Maybe these are really FET's? Or is it the the current limit feed-back feature on each output that lets us get away with it? -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC/EMC CNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending Craftsman AA 109 restoration Shizuoka ST-N/EMC CNC) ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
