110v-230v AC to Mysensors PCB board

[Quinie]

I still have trouble figuring out the C1 and C2. Here are some picture of my build so far.
Not sure all the components are placed correctly.

C1 is placed with a small 100nf (104) but BOM in zip say's this is wrong.
As you can see i placed this one, cause the 100uf will not fit

[AWI]

@Quinie looks correct. This is the position of the large capacitors (mind the polarity - minus to the edge of the board)

I also noticed you mounted the regulator correct. ;-)

[shabba]

So the regulator needs swapping about and the BOM cap values are incorrect from post (http://forum.mysensors.org/topic/1540/110v-230v-ac-to-mysensors-pcb-board/37) above that states :::
C1 100nF capacitor
C2 100uF capacitor
C3 4.7uF capacitor

?

[bjornhallberg]

Hmmm. I got the 5.5V DC varistor from another AliExpress seller and I'm a bit puzzled as to why it starts smoking after a few seconds. Tried several of them. The HLK gives a solid 5V output. I'm assuming I got some lower voltage varistors by mistake?

[AWI]

@shabba Right... if you look at the schematics you can see that the two capacitors can be swapped without consequences

[m26872]

@bjornhallberg Maybe I've missed reading something, but why use a varistor for 5 Vdc and not a zener diode?

[shabba]

@AWI Thanks! Very true!

[bjornhallberg]

@m26872 You're probably right, I just followed the BOM. I'll see if I can stock up on some diodes from AliExpress for future use.

[korttoma]

Whould a 5.1V zener work?

edit: removed the link to the product so that no one would buy it the specs of it is to tight to be used with HLK.

[Cliff Karlsson]

Just a stupid question, the "G3MB-202P DC-AC PCB SSR In 5VDC,Out 240V AC 2A " What happens if I forget and plug something more power-hungry like a toaster or a microwave-owen? does any of the fuses blow or does the relay break ?

[korttoma]

there is no fuse on the relay switch so I guess either the PCB or the relay will fail.

[m26872]

I've seen commercial products with a thermal fuse glued to the switching side of the relay. Maybe that would help some in such situation.

[m26872]

@korttoma A 5.1V zener is probably too tight. The HLK seems rated 5+/-0.2V.

[bjornhallberg]

@m26872 Indeed, mine is 5.08V (with no load). I ordered some 5.1V and 5.6V 1206 SMD diodes from Ali for future use. Plus some 3.6V. And a set of DIP diodes.

[rvendrame]

@bjornhallberg said:

I ordered some 5.1V and 5.6V 1206 SMD diodes

Just to remember, the typical zeners are 1W , which gives a max of 200mA of output capacity, pretty enough for Arduino+radio, but maybe not enough for many relays / Leds etc. And if they burn due overload, they will allow all voltage/current flowing from PSU into arduino.

That explains why we suggested the varistor, in order to short the PSU output and trigger its internal protection. Strange that your varistors didn't survive... Bad lot? Maybe they are not 5.5V as stated?

[m26872]

@rvendrame
No.
The zener will only lead current during over voltage condition and only needs to dissapate enough energy till one of your (multiple?) over current protection trips. Just as your varistor setup is supposed to work.

[rvendrame]

@m26872 , is it also true in case the PSU itself fail? And what happens if the circuit consumes more current than zener rating? I'm my (poor) knowledge, zeners are more relevant for stabilization, while varistor are effective 'protection' devices...

[shabba]

@mvdarend You discover your issue with the relay?

[m26872]

@rvendrame
since we're discussing the PSU secondary side (output side), I think we already presume errors with the PSU. A fuse (over current protection) on the secondary is not just there as a back-up if the PSU internal over current protection fails. The fuse will also prevent your over voltage protection (zener, varistor, ...) from overload/burn/start a fire.

The current from PSU to load will not pass through the zener and hence the rating is irrelevant from that perspective. In other applications where a zener is used as voltage regulator, the full load current will pass through the zener when in idleing and then the rating is critical.

[korttoma]

@m26872 so how do we need to rate the zener? Should the zener be rated so that the fuse will blow before the zener brakes from the current it passes due to an over voltage situation? Or is it OK that the zener brakes to as long as it takes out the fuse first. Then an automatic fuse will no longer work.