Running microprocessor from harvested triac as switch transients

[staneda]

Attached is an image of a plain vanilla ssr, composed of a MOC3081, zero-crossing opto-triac, and a triac. There is also a snubber network. I need to run a microprocessor, and logic from residual voltage transients when the triac is on. That's the purpose of the floating bridge. This is a challenge since the mains neutral is not accessible at the site. The triac controls from hot to load. The bridge in the picture is attempting to rectify the transients. The 5v battery input to the opto is just there to aid in spice simulation. The harvested voltage from the bridge would replace it. I need 100ma at 5v. An LDO has to be driven from an ac/dc converter with an input range of 80-110vdc rectified (not in the picture). The bridge can deliver 110vdc rectified just fine with the triac off. With triac on, this falls to 20v, and 10ma into a 2k load. Has anyone encountered this "chicken-and-egg" problem before? Is the solution obvious to a power pro?

Stan

 

[ahsan_i_h]

If your load current does not vary too much then you can use a CT (current transformer) to harvest power when the triac is ON. But you need to make a custom CT.