On Thu, Aug 13, 2009 at 8:34 AM, Roger Weichert wr= ote: > And also the supply. From the data sheets I see that 5.6 volts is too hig= h. > > I may just be showing my ignorance =A0... =A0but if this other microcontr= oller > has worked for 20 years with such a crude supply (5.6volt zener and a cap= ), > is it possible that a 5 volt shunt regulator could be used =A0.. =A0(is t= here > such a thing?) ... to keep it safe. > You can add a SOT-23 LDO regulator to your adapter board. MCP1700 or something. 5.6->5.0 V is an easy spec to meet. Read the datasheet and add the capacitors it asks for. Note that the microcontroller that worked for 20 years is not working any more... so maybe 5.6V was a bit high for it. The PIC internal osc works fine, but if I was in your shoes I would probably re-use the crystal. I'm sure you're right about accuracy not being super-important, but I like to have RS-232 configuration / debugging in my designs, and a crystal makes a better baud rate generator over temperature than the internal oscillator. Regards, Mark markrages@gmail -- = Mark Rages, Engineer Midwest Telecine LLC markrages@midwesttelecine.com -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist