Do they use PWM? If yes, what frequency?
It looks like they do: https://github.com/sparkybg/UniSolder-5.2/blob/main/software/front/US_Firmware.X/PID.c#L340. Their PID controller is adjusting a duty cycle in the end. I don't know what their frequency though, It's not clear from their github.
maybe their PID algorithm is just weird or they use bad or non-optimal parameters. I wasn't able to full reverse-engineer it, yet
Oh, you are in this thread, lol. I didn't look.
Spectrogram is just an Audacity option (or whatever variant of -acity is politically acceptable these days; I have an old version for what little audio work I do so I haven't paid attention to that stuff).
Tim
And here i was just assuming that it depended on the grounding... (for example if you touch the tip to a grounded objects whilst soldering, or if the aixun base station is plugged into a poor grounding, or if the 1mohm static grounding resistor explodes due to static shocks, things like this).
Aha, so it's not the element buzzing, it's the supply.
...
That suggests the noise is probably core magnetostriction from the supply throttling up and down regularly (and suddenly); it might even be going idle inbetween pulses. Replacing the supply with a quieter one is the most expedient route. Digging into the SMPS yourself would be... more challenging.
i think you have to ultimately realize that at least 1 component somewhere in the box is making a sound. and whether thats from a magnetic coil, or its a microphonic peizo from an mlcc or something else. then that component either isn't locked down properly enough, or it's basically gone faulty / bad and may be a subject for possible replacement. since it's making a noise after all...
I suppose I'm still only assuming it's SMPS, as I haven't seen complete up-close internal photos of this thing.
The fact that no one else has reported noise, does sound suspicious.
510Ω resistor for the opto LED off a 24V rail?
i cannot help you here on my unit because... it never buzzes. it's totally fine under all of the circumstances
Aha, so it's not the element buzzing, it's the supply.
@drsky does it also buzz when supplying the 24V from your bench supply but without your circuit?
And here i was just assuming that it depended on the grounding... (for example if you touch the tip to a grounded objects whilst soldering, or if the aixun base station is plugged into a poor grounding, or if the 1mohm static grounding resistor explodes due to static shocks, things like this).
My understanding of the way Aixun determines if a hand-piece is installed is by 1-checking the ID pin, and 2-reading out the thermocouple voltage. So putting this 47n cap is likely throwing off the thermocouple readout, but how though?
And here i was just assuming that it depended on the grounding... (for example if you touch the tip to a grounded objects whilst soldering, or if the aixun base station is plugged into a poor grounding, or if the 1mohm static grounding resistor explodes due to static shocks, things like this).
Maybe it is a grounding issue. Could it be a bad solder joint? Maybe the power header that I've trusted so far is just a bad one. 11PM rolled around and I had to head back. More tests remain to be done.
My understanding of the way Aixun determines if a hand-piece is installed is by 1-checking the ID pin, and 2-reading out the thermocouple voltage. So putting this 47n cap is likely throwing off the thermocouple readout, but how though?
Well, I believe I was told that the id pin is meant for T12 handle identification purpose. Because in my unit, it's T245 handle. And in that handle's wiring the white wire is bridged to the green wire (-). For which green color is the GND wire. So presumably when ID=GND then the MCU on the controller PCB (the software). Checks that GPIO line and determines that 0v = T245 handle. And something else (whether floating or otherwise some specific value). Would then pertain to a T12 tip.
Well I am not any sort of expert on mains grounding - far from it! But my understanding is that a poor quality (or even completely "gone", or intermittent) installation ground can occur within the room level. (or as you say on the socket strips etc). Or it can occur at the building level, or it can be that the stake driven into the soil, with respect to being tied also elsewhere locally in the incoming feed or the wider neighbourhood. But generally speaking: it's more likely in certain places or locations than other locations. So the level of suspicion eh, maybe there are professional electicians tools to measure ground connectivity. In a certified fashion. I do think it's not my business really to comment for how to go about determining such things.
As for the handle buzzing. I simply do not understand that. However is this T245 handle you are talking about? --> the logical step might be to request new handle then. Because some of these handle can be known issues. And if you are sent new handle then you could also (later on) destructively dissassemble the old buzzing handle to look inside of it.
i cannot help you here on my unit because... it never buzzes. it's totally fine under all of the circumstances
Thanks. So that puts to rest the theory that all Aixuns buzz.Aha, so it's not the element buzzing, it's the supply.
I'm still not convinced that it's the power supply alone causing this.
@drsky does it also buzz when supplying the 24V from your bench supply but without your circuit?
Yes, it does. I went back to the lab today for further hacking. In fact, I was wrong in my previous assumption. The circuit that I previously said does not buzz, with external power switch and bench supply, did in fact make a buzzing sound from the handle . When the cartridge was connected mid-air, there was no noise, but when I used the handle, the handle was buzzing. Also, providing an isolated supply for the digital section did nothing.