As i now realise he response is far too slow to give that information usefully. I think I will measure the amps and volts directly using transformers __________________________________________ David C Brown 43 Bings Road Whaley Bridge High Peak Phone: 01663 733236 Derbyshire eMail: dcb.home@gmail.com SK23 7ND web: www.bings-knowle.co.uk/dcb *Sent from my etch-a-sketch* On 20 February 2018 at 21:12, Neil wrote: > Photodiodes & phototransistors should be much faster than > photoresistors, so cleaner edges. I believe photodiodes have the > fastest transistions so a schmitt trigger may not be needed (other than > the I/P of the microcontroller). > > I like this project idea... would be nice to see how things change as my > 3D printer, fridge, A/C, etc comes on, without having to move around a > plug-in power monitor. > > Cheers, > -Neil. > > > > > > On 2/20/2018 5:34 AM, Clint Jay wrote: > > In all the energy monitor projects I remember seeing I've not seen a Cd= S > > cell used, not that I think there is anything wrong with that idea, > they've > > all used a phototransistor or photodiode, I seem to remember one that > used > > an LED... > > > > The late John Becker had one or two published in EPE that were Pic base= d, > > might be worth seeking those out? > > > > On 20 Feb 2018 10:29, "David C Brown" wrote: > > > >> This is one of those so trivial problems that shouldn't need advice > but, as > >> so often with me, I have over researched to the point where Ic an't > make a > >> decision. > >> > >> Since I am not going to get a smart electricity meter real soon now I > >> intend to build my own power monitor. The meter has a red LED which > >> flashes 1000 times per kWh and the key to the project is measuring the > time > >> between flashes. > >> > >> But I can't decide the best way to detect the flashing LED. CDS phot= o > >> resistor followed by a Schmit trigger; photo transistor followed by a > >> transimpedance amp. There should be no problem excluding ambient lig= ht > >> and the LED flashes for about 1/2 second. > >> __________________________________________ > >> David C Brown > >> 43 Bings Road > >> Whaley Bridge > >> High Peak Phone: 01663 733236 > >> Derbyshire eMail: dcb.home@gmail.com > >> SK23 7ND web: www.bings-knowle.co.uk/dcb > >> > >> > >> > >> > >> *Sent from my etch-a-sketch* > >> -- > >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > >> View/change your membership options at > >> http://mailman.mit.edu/mailman/listinfo/piclist > >> > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .