I measured the resistance of the motor and both heating coils

mg512 wrote:
... you need to overspec the power supply anyway, as start-up current is much higher, and not as easily measured. Bottom line, get a 5A PSU, and most likely it will be fine....

... if you end up driving the primary heating coil directly from mains as in the guide, that will also significantly up the wattage it draws! ...This too is something I wouldn't worry about

mtbizzle wrote:

I have the popper disassembled, intending to try to measure voltage and amperage of the fan for making a call on a fan PSU, based on what you said I guess I shouldn't do so.

I know in your guide, you say,



If I should do this, v.s. going with the '18v' sticker to use my 19v7.1 PSU, can someone point me to where I would put the multimeter red/blk to measure this? I also don't know how to use this ohms measurement to calculate the values I'm looking for.





I have a 19v 7.1a laptop charger that I am hoping to use for this purpose, but of course only if it is appropriate. The unit just attached to the diodes in the picture above (fan & motor to my understanding) has a sticker '18v'.

So 19v would be a slight overvoltage but indications seem to be that won't be a problem.

What about amps? 7.1a. Just want to be sure, mains electrical and all.



Once I settle this PSU matter, will be moving forward with the build

mtbizzle wrote:

I just came across this thread over at Home Barista, discussing an issue with a PID arduino sketch that they seem to have fixed. https://www.home-...63751.html

"Inconsistent power scaling"


I know in MG512's guide, he indicates either of two arduino sketches can be used. Does anyone know if either of those exhibits this issue, or if one/both don't have this problem?

hstan4 wrote:

I?m excited to see the progress on mtbizzle?s air popper. I just recently got into home roasting and too have a Nostalgia air popper. I?m highly considering getting the TC4+ and hoping I can figure the wiring and other parts out without too much trouble. I love the in depth responses here and am looking forward to participating on the forum.

One thing I?m struggling with is determining which options to add to the TC4+. I?m confident I can learn the through hole soldering without too much trouble but don?t know how difficult configuring the status lights etc would be into this setup (or if it?s not too difficult) if I don?t get the preconfigured options.

I?d love to have it configured to ensure there?s little room for error, but also am really curious to truly understand how it all works, so want a good mix of both to ensure I can get it working.

Either way I?m glad I found this forum and have loved what I?ve learned so far. Thank you all for the contributions and awesome TC4 shields

renatoa wrote:

Attached you can see the heater plate of the popper I am actually modding... just for the record.
The bimetal on the right has the same function and connection as the thermostat in hstan4 model.
The fiberglass cloth white tube on the left is an insulation for the thermal fuse we can see naked in the pictures above.
By far I prefer hstan4 model, there is non need to dismount heater plate in order to bypass the bimetal, and the thermostat leads can be used for SSR connections with less much tinkering.
...

mg512 wrote:

Oh, interesting, is that red/brown wire connected to a thermostat on the roast chamber? Haven't seen that before.

As far as I can tell from the pictures, renatoa has it right:

For the fan, you can either desolder the rectifier diodes, and solder wires and a flyback diode directly onto the motor terminals. Or, in principle, you should be able to keep the rectifier diodes as they are, and they should act as a flyback as well. I've never done this in practice myself, but in principle it should work.

For the heater, there is most likely indeed a seconday heating coil nearer the center of the assembly. You should be able to see it if you hold the assembly sideways at the right angle. And it looks like the wiring of the heating coils is indeed a bit different than what I've seen before. If I am piecing this together correctly from the photos (but double check all of this!) it looks like the main heating coil is connected to blue and brown, which are neutral and live AC. AC Neutral is then also connected to one side of the secondary heating coil through that metal bar / tab on the heater assembly. The other side of the secondary coil connects to the white wire which goes to the fan, the other side of which is connected to AC Live. So fan + secondary are in series, and connected directly to AC. (Most machines I've seen before had fan and secondary in parallel, and connected to neutral and one end of the primary coil.) Assuming this is all correct, you would indeed use the blue and brown wires from the heater assembly. I might be wrong about this of course, hard to tell for sure from pictures. Double check all of this, and if you're not experienced with working with AC ask an electrician for help!

harryf wrote:

I have just finished connecting up my popper roaster setup as in the instructables article, and have a problem with thermocouple readings. if I leave the fan psu off, and click "ON" on Artisan, the readings are correct, but as soon as I switch on the psu the readings are garbage. This is with fan and heater off. I disconnected the psu and connected my bench psu and everything worked great, even with fan and heater on.I am using the same type of psu module as in the article. This is driving me nuts. Any ideas?

ps i checked the ripple on both PSUs with my multimeter and they seemed about the same, but with no oscilloscope I can't be sure.