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A project log for AC Safety timer

Turns your soldering iron off after a half hour

Nick SayerNick Sayer 02/13/2018 at 16:060 Comments

If you’re going to build one of these, for the love of God, don’t apply power to it unless the case is all buttoned up.

This, in particular, means don’t program the controller with power applied. 

Not only is it a pretty dumb idea to be messing with the board while 120V is hooked up, but in addition the programming lines are shared, and one of them drives the LED in the opto-isolator. If power was applied, it would flick the triac on and off, which would be bad for any load connected and for the snubber components probably.

For the same reason, don’t push the button while programming, as that would mess things up.

If programming doesn’t work, it’s possible that your programmer can’t overcome the impedance imposed by the LED. If this happens, just temporarily remove the 150Ω series resistor (or get a better programmer).

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