I would use a phototransistor.

Select a PIC which has analogue op-amps and a CCP module. Use an opamp for =
the amplifier and the CCP module to measure the flash rate.

You should then be able to come up with a program that measures the rate of=
 flash to come up with a consumption figure.

I would be interested to see what you come up with.



> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
> Of David C Brown
> Sent: 20 February 2018 10:29
> To: Microcontroller discussion list - Public. <piclist@mit.edu>
> Subject: [EE} Detecting a flashing LED
>=20
> 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.
>=20
> 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 ti=
me
> between flashes.
>=20
> But I can't decide the best way to detect the flashing LED.   CDS photo
> resistor followed by a Schmit trigger;  photo transistor followed by a
> transimpedance amp.   There should be no problem excluding ambient light
> 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
> <http://www.jb.man.ac.uk/~dcb>
>=20
>=20
>=20
> *Sent from my etch-a-sketch*
> --
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