On Friday 07 March 2014 22:46:26 andy pugh did opine: > On 8 March 2014 02:27, Gene Heskett <[email protected]> wrote: > > And that 24 volts, that is 9 more than the ULN2003 will be happy at > > No, the ULN is rated to 50V
It might be rated at 50 volts Andy, but its also rated at .5 amps. It doesn't chop to regulate the motors current. Ergo it turns on with 50 volts available, the motor has perhaps 6 ohms of resistance per winding. So you either put a 100 ohm lotsa watts resistor in series with the winding centertap, or you have a bowl of popcorn with bits of epoxy B scattered about. Thats a good way to get a decent speed but wastes a lot of power too. The Fairchild (old) data sheet I looked at tonight recommended 15 volts or less. The package is still a 16 or 18 pin dip, and more than 2 watts dissipation will soon cook it. The minidip doesn't lend itself to having heat sinks glued to it. With the thermal R of the package, you might get by, with a good heat sink, 650 ma through it. I have blown a couple playing. Its not at all hard to do with a 3 amp, 13 volt CB radio supply. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> NOTICE: Will pay 100 USD for an HP-4815A defective but complete probe assembly. ------------------------------------------------------------------------------ Subversion Kills Productivity. Get off Subversion & Make the Move to Perforce. With Perforce, you get hassle-free workflows. Merge that actually works. Faster operations. Version large binaries. Built-in WAN optimization and the freedom to use Git, Perforce or both. Make the move to Perforce. http://pubads.g.doubleclick.net/gampad/clk?id=122218951&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
