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Dave Berkeley wrote: > Tom > > Interesting. With the comparators you will be able to make a zero crossing > detector, to sync with the mains, perhaps using an opto isolator, across a > diode bridge? You could get it to generate an interrupt you. The PWM shouldn't > be a problem. The timers will do that for you. > > You can also be more advanced by using internal timers to ensure a zero crossing event is within an expected window and not a noise induced event or even multiple zero crossings being detected. This is a real issue, we have had to protected against this with machines we have in China, the mains is terrible and results in horrible things happening on pure zero crossing detectors. > I'm not sure about grid connected though. I've always wondered how you do > that. Any pointers? > > Are you planning on feeding some form of renewable energy (solar perhaps?) > back onto the grid? > > The thing that always struck me about PV solar is that is generates DC. If you > convert that to AC with an inverter you take an efficiency hit, which results in > much of the power being lost. If you are powering electrical kit, it often > converts the AC back to DC, with another conversion hit. Chances are you are > throwing away half of that expensive solar power in conversion costs. > PV solar always seems to be to be very very expensive for the power density possible. Where as you could probably home brew a wind generator capable of 1000w for comparably little expense. Switch mode conversion is pretty efficient and can also deal with wider voltage input range, even powering pure DC equipment you may need a switch mode stage to ensure you have the required voltage for your equipment with variable supply. > The machine code for the PIC is a bit odd, but nothing clever about it. Very > straightforward. It will be just like machine code was 20 years ago! Have fun. > Keep us posted. > > Pics do give quite powerful instructions, such as access to AD and DA convetors with basically 1 instruction, where as in the good old days you would have to write a driver and clock various data/address/io lines around to talk to external chips where as this is all embedded in pics. They are very focused little devices that are still very relevant and Microchip has expanded the range somewhat with some higher end processors now. USB, CAN Ethernet etc are standard on some ranges and make creating devices for USB or remote networking far simpler that it ever was. Robin -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html