Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" s...@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com Quoting Gerhard Fiedler : > Russell McMahon wrote: > >> With say 0.5 mA drive you need a transistor current gain (Beta) of >> 80/.5 = 160 which is achievable with many of the more capable small >> transistors. I'd use BC337 here but there are many others. > > Wouldn't you need an extra diode with a bipolar transistor that you don't > need with a MOSFET (built-in)? That's the reason I suggested a MOSFET. > > Gerhard Unless the MOSFET is avalanche-rated for the coil energy you need a diode anyway. The parasitic body diode should never conduct. Best regards, -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist