EEVblog Electronics Community Forum

Electronics => Beginners => Topic started by: bitshift on September 10, 2015, 02:20:49 pm

Title: Watt Meter Schematic Questions
Post by: bitshift on September 10, 2015, 02:20:49 pm

Hey guys,

I've been studying this (http://www.electro-labs.com/wp-content/uploads/ac-wattmeter-schematic.jpg) schematic for a digital watt meter.

Why is the diode D1 connected in series with the supply pin of the PIC?

Title: Re: Watt Meter Schematic Questions
Post by: AF6LJ on September 10, 2015, 02:33:23 pm

That is a really good question.
I'm not sure...

Title: Re: Watt Meter Schematic Questions
Post by: DmitryL on September 10, 2015, 02:35:31 pm

Quote from: bitshift on September 10, 2015, 02:20:49 pm

Hey guys,

I've been studying this (http://www.electro-labs.com/wp-content/uploads/ac-wattmeter-schematic.jpg) schematic for a digital watt meter.

Why is the diode D1 connected in series with the supply pin of the PIC?

Take a look at J3. It is used for in-circuit PIC programming. D1 prevents powering up whole circuit from the PIC programmer.

Title: Re: Watt Meter Schematic Questions
Post by: bitshift on September 10, 2015, 02:42:10 pm

Ah I see! Thanks DmitryL  :-+

Title: Re: Watt Meter Schematic Questions
Post by: AF6LJ on September 10, 2015, 02:45:49 pm

Quote from: DmitryL on September 10, 2015, 02:35:31 pm

Quote from: bitshift on September 10, 2015, 02:20:49 pm

Hey guys,

I've been studying this (http://www.electro-labs.com/wp-content/uploads/ac-wattmeter-schematic.jpg) schematic for a digital watt meter.

Why is the diode D1 connected in series with the supply pin of the PIC?

Take a look at J3. It is used for in-circuit PIC programming. D1 prevents powering up whole circuit from the PIC programmer.

:)
Thanks, makes all the sense in the world now.