IC for 12V Latching relay board

@tedbear There should be a number on the IC. You will need a magnifier to see it though. None of my relays are latching so can't help. I did a blowup of the image and get STC15F104W. See attached file. All other files I could find are in Chinese. NOTE, in many cases the IC is not really needed so a little experimenting and metering may bear fruit.

@zander Thanks for the efforts.  The markings appear to be overwritten with a black magic marker.  As I said in the original post, with a failed board, putting in a known good IC from a working board caused it to work properly again. This is why I'm quite certain that getting 3 new ICs will bring those boards back to normal again.  The boards weren't terribly expensive and I will probably just throw them.  Some of the boards with a failed chip operate as a non latching relay with the N.O. and N.C. terminals reversed.  Common is connected to N.O.  when the trigger is applied Common becomes connected to N.C.  Although this is "backwards" the board could still be used as a common relay with reverse output. I will probably mark them with a note and may make use of them in a project not requiring a latching relay.  I was thinking that my ICs are some type of R-S latch rather than a microcontroller.  

@tedbear Ok, I read that the IC is so cheap in China they use it even if not strictly needed so you might also investigate that. I found the 10mb factory spec sheet but it was 100% Chinese but somebody over here made an English language version.

Good luck with your experiments.

@zander 

 I found the 10mb factory spec sheet but it was 100% Chinese but somebody over here made an English language version.

Maybe it can be scanned by an optical character reader.

Or better still maybe the free world will get back into building its own electronic components.

@robotbuilder I already gave him the PDF

@robotbuilder Only if the workers can live off the same wages they make in China. That is determined by the rest of us demanding and getting cheaper goods. It's a classic I'm all right Jack or my end of the boat isn't sinking.

@zander

Posted by: @zander

@robotbuilder Only if the workers can live off the same wages they make in China. That is determined by the rest of us demanding and getting cheaper goods. It's a classic I'm all right Jack or my end of the boat isn't sinking.

Not always true!

As an Australian, I'd rather pay more to support my country, but my bastard government (past and present) are screwing us all in collaboration with that FOOKED UP WEF/WHO!

Take them all to the guillotine I say!

We must change and fight these corrupt bastards!

OK, RANT OVER... BACK TO NORMAL DISCUSSION 🙂

I'm still hoping to find a way to determine the IC number. Maybe obtaining a limited number plus the shipping and handling make this unrealistic. 

I'm happy to report that the one remaining working IC and one of the boards was put into service yesterday.  So far it is working as desired.  My goal was to control a bank of several overhead lights in my farm shop.  The electrical load is fairly significant and a contactor is used to control the lights.  The latching relay is used to toggle the contactor.  This means a low voltage source can cycle the latching relay which in turn controls the contactor and lights.  A 12VDC pulse will toggle the latching relay. This pulse can come from various sources and locations.  One location is a momentary push button by the walk in door, another is an RF relay board controlled by various fobs, a third is an ESP32 relay board controlled from my phone or tablet in soft point access mode.  Any of these can change the status of the lights.  More momentary push button switches could be added by attaching them in parallel to the trigger circuit but due to the layout of the building this is likely unnecessary. 

Posted by: @frogandtoad

@zander

Posted by: @zander

@robotbuilder Only if the workers can live off the same wages they make in China. That is determined by the rest of us demanding and getting cheaper goods. It's a classic I'm all right Jack or my end of the boat isn't sinking.

Not always true!

As an Australian, I'd rather pay more to support my country, but my bastard government (past and present) are screwing us all in collaboration with that FOOKED UP WEF/WHO!

Take them all to the guillotine I say!

We must change and fight these corrupt bastards!

OK, RANT OVER... BACK TO NORMAL DISCUSSION 🙂

I think at least some of your ire is misdirected. When the auto workers in China get a tiny fraction of the union workers in america where would you build your factory? I think it's our collective governments who keep as much manufacturing here as they do with subsidies etc. Of course we do pay for that via taxes. It's always painful during the transition, imagine being a horse drawn buggy manufacturer when the car was just hitting the road. We survived once, we will again.

@tedbear I gave you the IC number, it's a 15F104W.

Hi @tedbear,

   Reviewing this discussion, it looks like Ron, aka @zander, has provided you with the number of the chip in the photo ... which is a microrocessor that needs to be programmed.

I sympathise with your thoughts that using a 'computer' to create a latching function feels like overkill, but from a practical view, if you are looking for a chip to 'slot' into the 8-pin socket, you probably have a problem.

My recall of 74 series etc. logic chips from the days of latches and so on, is the minimum size was 14-pin, with 16, 18 and 20 being popular 'upgrades' .. 8-pin packages tended to be reserved for op-amps and the like. So I think it is unlikely you will get a 'drop-in'. Perhaps, if you are willing to cope with 14/16 pin dip, then a single 74 series chip could do the job ... but whether it is worth the fuss and cost is up to you. As these are essentially obsolete, you will need to figure out what can still be obtained.

An alternate approach might be to persuade your Arduino (or equivalent) to do a little more. I presume the 'broken' boards have the micro driving the gate/base of a transistor ... as the relay has a 12V coil, whilst the micro limit will have been 5V. Hence, by identfying the output pin of now defunct micro, and driving that from a 5V Arduino is (electrically) a possibility. Thus the Arduino wil be reponsible for coordinating the different inputs and providing the latching logic. (3.3V boards, including the ESPxxx, need more care!)

Please bear in mind, technical data on this board on Amazon is non existent, and I haven't got one to examine ... I am only suggesting a course of action to consider .. you need to check it yourself ... I am not responsible if your Arduino also expires!

Take care .. best wishes, Dave

@davee Just google the IC number there is lots of chatter. The chip is common as dirt in china and in fact may not even be needed they jist toss them in to justify the cost. I recll seeing some chatter about bypassing the chip as it was not really needed.

Hi Ron @zander,

  The blank chip may be readily available ... but it will need programming ... which is feasible if you are used to programming blank microprocessors with your own code, but is a few steps beyond the average Arduino situation.

And i agree, whether it was needed depends upon the individual situation .. hence my comment of 'An alternate approach ....' , which considers dispensing with the chip.

If @tedbear is relying on the latching functionality provided by the micro, then that needs to be replicated somewhere .... and the driving Arduino is the obvious first candidate.

Best wishes my friend, Dave

@davee @tedbear Perhaps the OP would be interested in reading the following arduino forum posts. I thought this part of the forum was of interest.

https://forum.arduino.cc/t/stc-15f104w-data-sheet-required/454955/14

The ESP8266 communicates over a serial connection called SPI which is what the 15F104 is there to do. In reality, it isn't needed at all to control one relay but the 15F104 is cheap as dirt in China and well, they use them for lots of things that need a few I/O. So why can't you control the relay? Because it is most likely wired to one of the port pins of the 15F104, not directly to the ESP8266. You can verify this by tracing the circuit for the relay coil, if this is something you're capable of doing (don't know your skill set).

So what I think you've done is break the software connection between the 15F104 and the ESP8266 by re-flashing the latter.

If I had a decent photo of the top and bottom side of just the relay board, I might be able to make out enough detail to say for sure the relay is controlled by the 15F104 and not the 8266 if you can't work out the connection details.

I note the part that says in part "It isn't needed at all"

FYI, YMMV