Hi All PICers ! b> From: Alan Nickerson b> Subject: Computer voltage control b> To: PICLIST@MITVMA.MIT.EDU b> b> I am trying to design a field programmer for a 16C84 that b> will be of production grade verification. Since software is b> my area of expertise and electronics a small part. I am b> looking for information to allow a PIC to control the b> voltage from 4.5V to 5.5V for the verification. b> b> Anyone have any suggestions? Simple and cheap is better. A b> little sophistication in the software is much easier for me. Alan, You want 4.5 OR 5.5, or 4.5--5.5 ? In my "semi production" programmer where Vdd is 4.5v OR 5.5v I simply use two diodes shorting by transistor. In full production, I used (and reccommend for You) chip from Analog Devices - AD8402, this is double 8bit (256 step) trimmer resistor with serial (SPI) interface, so You need only 3 wire to control Vpp and Vdd by 2 chips (AD8408 + double OP). Best Wishes, Alex Torres. Kharkov, Ukraine, exUSSR. E-Mail To : altor@cook.kharkov.ua via InterNet or 2:461/28 via FidoNet --- GoldED 2.50.A0531+