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Drive 4 triacs with a PIC which is driven by an accelerometer impulse

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Newbie level 6
Apr 12, 2011
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Hi I need some help,
I want to transform, in my circuit, a double inverter relay (too big), in an electronic control.
The only way I've found, is 4 triacs (one in each wire the relay was commuting) with their trigger controlled by a microcontroller.
The circuit is driven by a reaction of an accelerometer which inform the chip (with an impulsion) that stops 2 of the triacs and in the same time supplies the others.
The problem is that I need 35mA in each trigger of the triacs and the maximum we should take from the output of a PIC is 5mA and the supply is a battery of 5V.
The second problem is the triacs,are they really reliable if i need a fast answer when i cut the trigger current?
And what is the best PIC to do this circuit (accelerometer and cut/give supply)?

Triacs are AC power switches and can't replace relays in general applications. You should clarify the kind of electrical circuit that is involved in the problem.

Particularly triacs:
- can't switch DC currents (they never turn off)
- are only (or mostly) suited for power circuits
- need heatsinks for higher currents and thus are not necessarily smaller than relays respectively contactors
- other than relays don't provide isolation between control and load circuit. Opto triacs (e.g. MOC3030) are often added for this purpose
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thanks for the answer,
I know it all but my purpose is a security breaking then my heatsink will be smaller.
i already have my opto but i don't know if i can drive with on impluse of the microcontroller two triacs in the same time. ( the trigger current is 35mA then take 0.7mA from the µC, which go drectly in the opto for isolation and then in an hfe=100 NPN transistor that would give me 70mA, 35 mA for each trigger.)

Considering a voltage drop of 1.3V for an IR LED, even a series circuit of both opto triacs inputs can work for 5V supply, saving half of the supply current.

Thank you but do you think i can drive all the triac with one microcontroller because there are just 1 A/D converter in all the PIC I have seen.
I don't even know if i can split the current for both the triacs because after the opto coupler I will be in AC and how could i amplify the current with an AC supply for a DC emitter to the triac's gate?

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