Schematic Mistakes

A project log for Home Power Usage Monitor

Gather power data from the breaker panel and beam it to a Raspberry Pi for storage and web serving

drew-yenzerDrew Yenzer 07/17/2015 at 00:380 Comments

The good news is the PCBs I ordered should get here Saturday. The bad news is there are horrible flaws in the design that would burn up one or more components. I may have jumped the gun in ordering those PCBs... stings.... Here's a list of them. The first 2 are from SJ Greenfield.

  1. Since the 9Vac source is grounded by the voltage divider AND the diode bridge, it shorts itself across the diode between pins 2 and 4 on the bridge every negative cycle. That diode bridge definitely would have smoked.
    1. SOLUTION: Go with a single diode half wave rectifier. This will require a larger smoothing capacitor.
  2. Resistor R4 should have a junction between R12 and R11.... Duh.
  3. Currently when the current transformer is disconnected, the switch in the stereo jack pulls the ADC line to ground. After looking at it again I think it would be better to send the divided 1.65V to the ADC so I can calibrate that measurement.
  4. Button1 is tied to pin RA7 on the PIC. RA7 just so happens to not have any interrupt associated with it, nor is it a remappable pin. Nice.
  5. Turns out the CSN pin on the nRF24 is more than just a simple chip select. You know, the simple kind that just enables/disables the entire chip. It actually needs to be pulled high and low when sending commands. Go figure.

Let me know if you guys notice anything else!