W1209 module with 5V

[scientistnobee]

Hi, I would like to make a small heat pad with 5V battery powerbank using W1209. However, all I found is 12 V modules. The 5V modules advertised in ebay/Aliexpress don't seem to have genuine parts. Could you please advise me how to get the genuine 5V module or how to convert a 12V module into a 5V module. I have seen a similar question in electronics stack exchange, but there is no satisfactory answer is given, particularly about MOSFET and relay.

https://electronics.stackexchange.com/questions/544292/can-w1209-be-run-with-5v-dc-only

[TG9541]

I had a look at the infos on stackexchange:

• when the USB powerpack supply voltage is in the 4.5 to 5.5V range connecting the anode of D2 to the output of the 5V regulator should work.

• After removing the 12V relay soldering a through-hole STP36NF06L at the same spot should work. It's maybe necessary to remove R7 so that the STM8S003 pin10 (PA3) doesn't get any additional load.

[krikoman]

Where's you relay sensor in relation to the heater, what sort of space are you trying to warm up.

My sensor is on the same heat sink as the heater, this is all enclosed in a smallish volume of 2,000 cm^3, and it's insulated from the outside.
My hysteresis on the devices is 0.5C and the temp. varies by around 0.75C depending on the outside temp. This could be improved by greater insulation, I think.

[krikoman]

OK just zoomed into the photo, so I can see what you've got set up.
If you insulated to block it might help smooth things out. It does seem a bit strange though the large range on something so small.

Do you have two probes on the controller?

Do you know what the temperature rating the cartridge is? It might be this is getting really hot very quickly and by the time it's sensed and witched off it's already way over the setpoint.

I tried to get one around the target temperature, but started off with one that was about 3 times over and it got hot too quickly. This meant the relay was switching more often than was required.

[scientistnobee]

Thanks for the suggestions. Second sensor is just laying around. It was not connected to the board. The cartridge sensor in the current set-up is 12V, 40W and resistance 4 Ohms. Now I changed the cartridge to 24V, 40W, resistance 12 Ohms. I got the following graph for 32 degrees set temperature, it is better than previous set-up with less resistance cartridge. Moreover, 5V w1209 module worked without any issue with this 24V, 40W cartridge. As you suggested, I will increase the resistance further to 20ohms with 24V, 30W cartridge. I hope I will get more flat response.

[scientistnobee]

The above graph was with a new module where I failed to check the hysteresis setting, which was kept at 2 degrees. Now, I am getting better results with hysteresis of 0.1 and P4 (correction term) of 3 degrees for a temperature setting of 37 degrees. All these with a cartridge of 24v, 40W. You can see +-1 degree change from 37 degrees (only see lat 3-4 cycles). I think I can improve this further by using a 24V, 30W cartridge, which is on the way.

[scientistnobee]

The correction term has to change at different temperatures, for example for 55 degrees, P4 is around 6.7 degrees.

[scientistnobee]

Thanks for your prompt reply. Is it okay to short input and output of the 12V regulator? Is there any link where I can buy genuine boards?

[TG9541]

Genuine boards are rare these days, and I was't able to find a reliable source (I tried!). I have a small stock, though, and maybe I can send one your way. Where do you live?

[TG9541]

I think that shorting in and out should be OK. The thing I proposed would result in a slightly higher supply voltage.
Genuine boards have become as rare as hen's teeth. I asked several vendors but the supply side appears to be dead. The last time I got a board with an STM8S003 controller was nearly two years ago. Today it's almost easier to design your own board with KiCad and have JLCPCB assemble it for you.

[scientistnobee]

I did some experiments with the module by just decreasing the supply voltage. I think circuit is working as it is with 5v without any shorting of voltage regulator, except the relay. What I am thinking is can I turn on 12v relay with 5v supply voltage, just by changing 2k resistor at the base of the transistor? Any suggestions?

[TG9541]

I would try it by changing just the relay. Measure the current and check if it's within the specs.

[scientistnobee]

Okay. I have potentiometer now, but no 5v relay yet. Also, I have to search compatible relay.

[TG9541]

It's best to be careful about the relay specs. A relay may switch-on at a certain voltage when it's cold but won't do that when it's warm (relays get warm while active).

[TG9541]

@scientistnobee I'll first convert this issue into a discussion thread

[scientistnobee]

Hi, if you don't mind me asking a silly question, I would like to know what is the role of R3 between the two diodes?

[TG9541]

To be honest I have no idea why the designer of the board decided to apply a 10R resistor in the 12V supply since the value of C5 is much too small for R3 to have a meaningful effect. The supply current is easily 0.15A, and that means that it leads to an additional power consumption of 0.2W.

[scientistnobee]

Thanks for your reply, I have several other issues with understanding the design choices. I wonder about this resistor the most. Also, while you are here may I ask, if there exist anyway to code this with Arduino IDE?

[TG9541]

It's certainly possible to find a solution with the Arduino IDE but I don't know how complicated it is to set such a thing up and how good the support for STM8 actually is. This is maybe a starting point:

https://github.com/stm32duino/Arduino_Core_STM8

You may also have a look at something that might be close to what you need but that will bring you in touch with a different technology:

https://github.com/TG9541/W1209

[scientistnobee]

Thanks for the links. I was aware of eFORTH, but I afraid of learning a new syntax

[TG9541]

The syntax is easy: there is none. The only thing is that it's "1 2 +" instead of "1 + 2". Function calls are "5 setADC" instead of "setADC(5)". This looks a bit strange but it takes just about 5 minutes to get familiar with.

There are also cases where the "C-way" looks awkward in comparison: instead of writing "f3(f2(f1(5)))" for chained functions in Forth it's just a chain of functions "5 f1 f2 f3" :-)

[scientistnobee]

Thanks for the nudge, I will give it a try and get back to you.

[VK6TT]

Hi Mark, sounds like a variant of the original W1209 boards which started Thomas on his journey. That means you will have to change the IC out for a genuine STM8 device.  There is a page in the wiki detailing how to avoid a clone. Scary for the first timer but not that hard in practice. I couldn't access your order details so I couldn't visually look at the board for you. Regards Richard

…

On 12/02/2021 6:44 am, krikoman wrote: Hi, I'm new to all this and know very little about electronics and flashing :) etc. I'm a electrical engineer with some C++ skills and that's about it. I recently bought 5V W1209, but not sure if it's the sort you can flash / program whatever it's called) I got it here https://www.ebay.co.uk/vod/FetchOrderDetails?itemid=293138632724&transid=1881944225019&ul_noapp=true <https://www.ebay.co.uk/vod/FetchOrderDetails?itemid=293138632724&transid=1881944225019&ul_noapp=true> It has a chip labelled as CMS8S588 2015CN, I can't find any details on this anywhere. I've been looking at this site, because I like the idea of logging temps and relay actions. But it all looks a bit scary and a bit beyond me. Anyhow, thanks for all the info, I'll might give it a go some time. Not sure if what I've posted is any use. let me know if you need more details, or if you can help on the chip ID of mine. I bought another one not long after a 12V with a case, really only needed the case. The chip on that one has no markings and is quite different from the picture on these pages. Cheers, Mark — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#399 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AE7PE27QS3U3DI5EXQAMXA3S6RMUNANCNFSM4W6CZBGA>.

[krikoman]

I thought it might be. It works great for what I need it for, though it would be better with more data, temps and relay operations.
I bought a 12V one (because it came with a case and I hadn't ordered one for my 5V version) but that has no markings on the IC at all, it was interesting to try it with my PSU, it worked down to 4.4V, but the relay wouldn't pull in (as expected) it needed 7+ volts to pull in the relay.
I put some photos up the thread, if you want more let me know.
I'm amazed how well these things work for how little they cost.