Inside A Circuit Breaker With MikesElectricStuff | 220v Contactor Relay

In my experience there are only TRIACs that are in perfect working order or TRIACs that have exploded.

I also seen a technique where a relay is placed in parallel with the zero crossing triac so the triac is only passing the load for 200ms or so while the relay switches. Since the triac is on longer than the relay, the contacts don’t arc over when switching, and the traic doesn’t pass the current all the time.

A capacitor stores electricity and is used during the compressor and fan startup for extra power. It also protects the motor from damage due to fluctuating voltage. These capacitors don’t last forever and can go out unexpectedly. If you are comfortable with electrical repairs you can use a screwdriver to discharge the dual start/run capacitor by connecting terminals to short it out, and then replace it with a new one made for the make and model of your A/C. If that’s beyond the level of DIY you’re comfortable tackling, then call a pro.

I seem to remember one test video I saw online, possibly BigClive, finding that the actual rating on the faux-Fotek SSR that he was dissecting was rated at around 10A, in a 25A labeled SSR. I believe it was also a MOSFET instead of the SCR or TRIAC that it was supposed to have, as well.

AC is safer than DC. You can let go of two AC terminals but not DC as DC keeps your muscles clenched. AC doesn’t.

Agreed, this is a house fire waiting to happen and your insurance co. won’t give you a cent if an investigation points to this homecooked thing as the firestarter. There are numerous commercial alternatives which are small enough to fit in a junction box _and_ are UL/FCC/CE approved. Granted, they aren’t as cheap as the ESP module and the triac described here, but in the end, most cheap alternatives to switching powerful currents turn out to be very expensive after all.

Buying from people you’ve never heard of, to get stuff cheaper, which is the only reason you’d use Ebay or Amazon, bypasses this whole chain of trust. And, fuck me! it turns out buying stuff from anonymous suppliers, in a market where Chinese scammers are an utter epidemic, sometimes means people don’t get what they expected to.

This is very dangerous. Safety regulations are all about keeping mains voltage away from people, inside casings that are earthed or double-insulated. This has the voltage just lying there. Possibly covered with a bit of silk-screened paint. It’s not guaranteed to kill someone, but for the extra money I’d sooner have a non-deadly heater for a 3D printer.

The rest of the circuit would be built on the backside, with judicious use of surface mount electronics rated for miltemp operation (to 125C). Standard connectors from Samtec or Molex can handle the current drive easily, with no problems from the heat. Add an acrylic conformal coat on the backside, or perhaps potting the electronics, and you can make the entire module one single brick module.

Yes, I have seen that sometimes (floating oscilloscope) but I always thought the good way would be to power the DUT through the isolation transformer and leave the oscilloscope safely earthed. Of course you sometimes need a bigger iso. transformer this way.

1. 25A for 22A? Too close for my comfort. 2. A thin sheet of aluminum is not much of a heat sink. 3. Sitting on top of the hot water heater means ambient temp is going to be a bit higher. 4. Summer in a garage is likely to get hot.

Xiaomi claims a screen-to-body ratio of 93.4 percent, and has cut down on the “chin” at the bottom of the display by nearly 4.5 millimeters compared to the Mi Mix 2S.