eBay opto isolator module

knowing lift engineers, it could be anything!

It isn't water. In fact it looks like coffee to me. The stain looks like it was dropped into it when horizontal then warmed up then ran after when it was vertical. Possible a splash a coffee or coffee enjoys someone was working in a bench. Eliminate the impossible and whatever is left the truth.

Michael Thompson

I'm perplexed at this one as it looks like water damage on a vertical PCB with full shielding above it.

Big Clive

That photo with the burned resistor and the drip...that is very similar of the photos that submit to customers when I have the regrettable duty to deliver the news that the warranty has gone bye bye and the unit will have to be re-quoted for repair. I work with a lot of HMIs used in food service and anywhere there are liquids in play washdown, cutting liquids. Yep. I'm that guy. 10 years last May as a matter a fact.

Michael Thompson

I think it's simplicity, as a capacitor would be bigger and also require a series resistor anyway. If the resistors are implemented like in the eBay module, then it's reliable.

Big Clive

Check out this from a project I did in 2011 - https://drive.google.com/drive/folders/15LANu75Vez7LpAcJviNxLAT_rcx3yAXg?usp=sharing - I didn't know about these modules then. Afaik, it's still going strong...

Gordo

Daft question: If the resistor heats up so much, why not use a capacitive dropper - is it a reliability thing?.. We need to go back to elevators powered by house-elves in giant hamster wheels..

Gordo

Very effective module. Not the easiest thing to mount though. Would almost require plastic hardware.

The 110V would make sense for the choice of resistor values and lack of crispiness, and also be a safer option for hunting down bad contacts in a safety circuit. The power and network approach is common in most industries these days. It saves on wiring and adds more features. But it introduces the plague of fault finding. Rogue CAN bus nodes that intermittently glitch the data lines or jam them completely.

Big Clive

The safety circuit on these controllers is 110vac seems to be the norm these days . Its a modular controller which uses a CANBUS to send data between the various nodes , car top, car operating panel ,landing pushes etc

I'm a huge fan of putting on diagnostic LEDs for everything. That way I can look at a PCB (or a photo of it) and often diagnose the problem right there and then.

Big Clive

I used to service and repair stage lifts and other similar specialist equipment. They share a lot of the same technology.

Big Clive

Clive, do you service lifts in your day job?

Mike Hanley

This was cool to watch! Thanks for the video that was a good one today

Michael Thompson

I got a Cliff Quickcheese for Christmas a couple of years ago. Awesome tool!

Michael Thompson

Here is a link to the Cliff Quick test (cheapest I have found) https://www.ebay.co.uk/itm/Cliff-CL1850-Quicktest-Mains-Connector/143266033931 I bought mine from maplin about 25 yrs ago at a cost of £7 or £8 they are usually around the £70 mark normally now, but this vendor in Bristol is only £48 or less

Mike Hughes

He doesn't live in the US, though?

Or just to clamp voltage spikes.

Frank

Maybe Zener to clamp the voltage and avoid capacitor explodage in unlikely event that LED/Opto fails open circuit?

Dave Davies

I think I'd kind of want an LED on both sides of the circuit, just so I can see "yes there's (nominally mains) voltage and yes the opto-isolator is switching".

Chris Crowther

It possibly is to cap the voltage. The current would be limited so it would be a slow foom.

Big Clive

I think that's a glitch. I'll have to try and suss out why it happened.

Big Clive

Uh-Oh... Similar title to the upcoming livestream... Demonitized by default?

Scott Miller

Speaking of the Cliff QuickTest, I received mine this week - North American style, with black/white/green clips instead of blue/brown/green. I should have ordered the UK variant instead as we seem to be using brown/blue for everything except in-wall wiring these days. Clive, would the zener be there to prevent the capacitor seeing full line p-p voltage and going "foom" if the LED or the optoisolator goes open-circuit?

Charles

Politics affecting shipping :-( ... so tired of all DT's drama

Peter Stevens