[EE] Detecting a flashing LED

[a***@stfc.ac.uk]

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-----
Of David C Brown
Sent: 20 February 2018 10:29
Subject: [EE} Detecting a flashing LED
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 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: [phone]
SK23 7ND web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>
*Sent from my etch-a-sketch*
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