Close

Reuse of old electronics.....

A project log for Automated Living Project

This is the umbrella project that encompasses all the aspects of the integration of electronics into our every day lives.

james-wynhoffJames Wynhoff 04/04/2018 at 20:440 Comments

I end up collecting, among many other things, old hardware, sometimes its a piece of hardware we really wanted to use in a project, sometimes its the being replaced by a newer fancier piece of equipment, and sometimes the only reason it failed in the first place was because of just a simple blown cap.

There are several pieces I have been holding for several years to finally make use of in my new house, and with the goal of getting all this incredible data, or ease of using an off the shelf product to satisfy the needs for the project, over the last few days I have been trying to get some of these products up and running for use...

The first one is the powerhouse dynamics emonitor12:

It has input on it for 24 CT inputs. What a great and easy way to start monitoring my power usage at the house right!

Well, to use this thing you have to pay a license fee every year to let it upload data to the cloud, but I don't want THEIR cloud, I want to be in control of my hardware, and my data...

Credit where credit is due though, I was already in product selection to roll my own board, and looking at this board gave me a few insights:

At its heart is a Lattice LFE2-12E, a pretty nice FPGA!

They offloaded the ethernet to a Rabbit RCM5750 module

Both of which have programming headers on the board, and they are populated!

The way they sample the CTs is what I thought was really interesting

they are using an (74hct4051d) 8>1 multiplexer(3) to get the 24 CT inputs down to 3 outputs from 3 banks of 8 CTs,  the address selection lines, 3 of them, got to the FPGA.

The output is fed to a dual channel op-amp (max4477), and finally to an Audio A/D Converter(Cirrus CS5341) that outputs i2s to the FPGA...... wait, what?

I can honestly say I had not thought of this design! But wait, 24 channels/8/2 is 1.5 ADC chips, where is the last input coming from?

The 12v AC feed gets its voltage dropped and fed into the last channel, I'm ASSuming that's how they are doing ZC (zero cross) detection.

More to come soon, as well as pretty pictures.

Discussions