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joejoe317:

--- Quote from: Ton on November 26, 2013, 10:58:12 pm ---Hi
The two inductors close together is a common mode coil, used to reduce noise

You could argue that it is a kind of transformer used to make the current in the two coi!s equal and in opposit direction.

Sorry for my English, hope it is understandable  :o

--- End quote ---

Thanks for the help on that one, I assumed this was the case, but I have never seen it before. Thanks again!

Your English is just fine Ton, thanks for commenting!
fcb:
Here's what I would do for the unit.

PSU
Power Integrations type switcher with flyback txfmr (three outputs, two of them isolated):
Isolated 5V for USB (with transistor based voltgae regulator and current limiter) - design it to run 2A into a short without melting!
Isolated 3v3 for microcontroller & RF sections, 12v (shared 0v with 3v3) relay.   This 0V is also NEUTRAL, this helps hugely with mains current measurement via a small shunt.

Put the regulation loop on the 12v rail and use a LDO for the 3v3 (noise), you'll need to do some 'mission profiling' to workout the minimum and maximum power draw and keep enough headroom, as a hint, if you design for perhaps 50% more power than you need you'll end up with a more efficient transformer design and have less swing on the rails.

Power monitoring
Roll your with a shunt in the NEUTRAL and use a differential amplifier (opamp). Plenty of detail on how to do this online.
Mains voltage can be sensed with a potential divider, use at least two high value resistors (2M2 perhaps) in series for safety.

Mains switch
Switch the LIVE via 12/16A 250V relay designed for mains switching (silver/tin based contacts) - schrack RT1 perhaps.
Switch the relay with a small FET and use a PWM output from the micro to do this, you can then do coil-economising.

Processor
MSP430 processor or similar with 14 bit ADC built in. You don't need the accuracy of the ADE7763, it's not metering for money.
Bluetooth or zigbee (makes sense if you have lots of sockets, and you can have a 'building manager' type hub, alot easier to develop too).
joejoe317:

--- Quote from: fcb on November 28, 2013, 11:03:36 am ---Here's what I would do for the unit.

PSU
Power Integrations type switcher with flyback txfmr (three outputs, two of them isolated):
Isolated 5V for USB (with transistor based voltgae regulator and current limiter) - design it to run 2A into a short without melting!
Isolated 3v3 for microcontroller & RF sections, 12v (shared 0v with 3v3) relay.   This 0V is also NEUTRAL, this helps hugely with mains current measurement via a small shunt.

Put the regulation loop on the 12v rail and use a LDO for the 3v3 (noise), you'll need to do some 'mission profiling' to workout the minimum and maximum power draw and keep enough headroom, as a hint, if you design for perhaps 50% more power than you need you'll end up with a more efficient transformer design and have less swing on the rails.

Power monitoring
Roll your with a shunt in the NEUTRAL and use a differential amplifier (opamp). Plenty of detail on how to do this online.
Mains voltage can be sensed with a potential divider, use at least two high value resistors (2M2 perhaps) in series for safety.

Mains switch
Switch the LIVE via 12/16A 250V relay designed for mains switching (silver/tin based contacts) - schrack RT1 perhaps.
Switch the relay with a small FET and use a PWM output from the micro to do this, you can then do coil-economising.

Processor
MSP430 processor or similar with 14 bit ADC built in. You don't need the accuracy of the ADE7763, it's not metering for money.
Bluetooth or zigbee (makes sense if you have lots of sockets, and you can have a 'building manager' type hub, alot easier to develop too).

--- End quote ---

Wow ty for the info, we changed the plans to use a msp430 because the programming board costs 10 dollars vs 150 for the cc430. The ade chip seems really easy to use and is cheap, so that is why we were using that.

I built an adjustable power supply before, it goes from 0-15V up to an amp with over current protection at 1A. It uses a darlington pair to boost current. I think I will re-look at how i designed it. It's really hard not having parts in front of me to tinker with. In class we are pretty much coming up with designs.

We found a nordic RF chip we were going to use that was only 2 dollars with the antenna circuit etc. We found a usb controller as well that came with drivers for windows/mac/linux/android, royalty free.


Would it be wise to shield the flyback circuit? I was wondering if the emf would interfere with any other parts of my circuit. Again just something I was watching about flybacks.

I can't really talk about the relay circuit yet, because our group has done limited research, but we were thinking we could tap off the 5v power supply and use a mosfet. We would then use a signal from the msp to turn off and on the mosfet to turn off and on the 5v power from the supply. I have seen other videos online where people used strictly a mcu and built a separate circuit with a bjt to increase the current to the relay.


joejoe317:
Happy Thanksgiving to all who celebrate!

Does anyone have any recommended books on circuits, I really like the encyclopedia of electronic circuits volume 3. http://www.amazon.com/Encyclopedia-Electronic-Circuits-Volume-3/dp/0830633480

JamesG-J:
Hey joejoe317,

I'm working on a similar project right now and was wondering how your project ended up and if you'd be willing to share some schematics or notes about the final product to help me along?

I'm trying to build a ZigBee controlled power bar with a bunch of relays - planning on using a shift register or two to control the relays using only a few GPIOs off the ZigBee.

Best,
James  :)
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