Fire hazard soldering stations Lukey
(I apologize for the quality of the photo)
Today I was awakened by the distinctive smell of smoke and the cries of my wife - "get up soon, you have something burning in the workshop there." After a couple of seconds, I saw the source of the fire that had almost begun - at the lukey 852d soldering station plugged into the outlet, the hair dryer glowed to a red glow, the plastic handle burned with vigorous fire.
So what happened? When all the consequences of the fire were removed, I opened the soldering station and was unpleasantly surprised. The fact is that the heating of the hairdryer in almost all hatches is controlled through a triac power regulator, which in this case received a PWM signal from an Atmega leg through an opto-triac pair.
This circuit takes power directly from the 220 volt input block, only the snubber RC circuit is all that is protected. When the BTA16 triac fails due to a voltage surge, the hair dryer starts to glow joyfully at all 700 with a penny of Chinese watts.
What to do?
1) Put in parallel with this triac a varistor with a cut-off of 275 volts - for short-term surges, the excess will dissipate in a spiral, and the triac will remain locked.
2) Open the circuit using a relay of 220 volts 10 A, hanging the control winding through a 1500 microfarad converter, a diode and a small transformer on the pump terminals. The logic is simple - if the pump does not work, then the power circuit of the heating coil is a priori open.
Well, do not trust the Chinese, leaving Uncle Liao's equipment unattended in the standbay, even if she worked without jambs for the last 5-6 years.