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Best way to interface Propeller with 120V AC — Parallax Forums

Best way to interface Propeller with 120V AC

Bobb FwedBobb Fwed Posts: 1,119
edited 2014-10-29 15:33 in Propeller 1
I would like to control an AC line with the Propeller. I'll be building a circuit board with proper safety and clearances in mind, but the circuity itself is a little bit of a mystery. The frequency of actuation is only about eight times per day, but I don't want to use a relay if I can help it (I prefer not including moving parts). Power requirements shouldn't exceed 150W.

I recall (a long while ago) seeing a transistor or that style of IC that could control high (~150V) voltage from a microcontroller-friendly (3-5V) input, but maybe I'm mistaken. Or should I be looking at optical isolation circuits?

Comments

  • ilovepiilovepi Posts: 9
    edited 2014-10-29 10:43
    Yes, you'll want both optical isolation (for safety) and a means to switch the power. For switching power, you can use a solid state relay or a triac connected to the propeller through the opto-isolator.
  • Bobb FwedBobb Fwed Posts: 1,119
    edited 2014-10-29 11:11
    ilovepi wrote: »
    Yes, you'll want both optical isolation (for safety) and a means to switch the power. For switching power, you can use a solid state relay or a triac connected to the propeller through the opto-isolator.

    Thanks. TRIAC that is what I was think of.

    What are TRIAC output optoisolators? (Like this one) I was hoping it was the perfect combo-IC, but while it has the voltage isolation rating, it doesn't seem to have the amperage rating of traditional TRIACs. It seems to possibly be designed to be used with another TRIAC, but what is the benefit of this specific type of IC then?
  • tonyp12tonyp12 Posts: 1,951
    edited 2014-10-29 11:13
    IXYS makes good PCB SSR ICs

    http://www.mouser.com/IXYS/Electromechanical/Relays/Solid-State-Relays/Solid-State-Relays-PCB-Mount/_/N-ay0ucZscv7?P=1z0zl5lZ1z0x39jZ1z0x10cZ1yzxot1Z1z0x3t5Z1z0x3sdZ1z0x1epZ1z0x1rs&Ns=Pricing|0
  • Alexander (Sandy) HapgoodAlexander (Sandy) Hapgood Posts: 360
    edited 2014-10-29 12:59
    I'm using 3 Crouzet Solid State Relays P/N 84134220 in parallel to switch a 6.5 horsepower, 115 VAC, 3 phase motor on and off. They're not PCB mount but they work well. The control circuit is 5 volts and the relays are controlled by a single transistor on the ground side of the control circuit.

    Crydom also make some PCB mount solid state relays you might look at.

    Sandy
  • jmgjmg Posts: 15,173
    edited 2014-10-29 15:33
    Bobb Fwed wrote: »
    What are TRIAC output optoisolators? (Like this one) I was hoping it was the perfect combo-IC, but while it has the voltage isolation rating, it doesn't seem to have the amperage rating of traditional TRIACs. It seems to possibly be designed to be used with another TRIAC, but what is the benefit of this specific type of IC then?

    Yes, they are designed to trigger a bigger triac, which then switches the some-amps load.
    The terminology when you have [Opto + triac] combination changes to Solid State Relay, and you can find plenty of examples at Mouser / Digikey. - right up to screw down types for 10+ Amps.

    SIL packages are good for 2~5A
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