FET: The Friendly Efficient Transistor
hackaday.com
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He mentions electrostatic discharge sensitivity. Yes. It's very easy to blow out the gate of an FET just by touching the gate lead. Once it's attached to a driver transistor, it's protected, but loose FETs need to be stored in conductive foam and handled while wearing a wrist strap.
FETs are really amazing. ON resistances in the milli-ohm range, and OFF resistances in the megohm range. It's surprising that's physically possible.
Unfortunately, we often rely on trusting secretive vendors with insulation specs, trusting assemblers with following instructions and not damaging hard to inspect wiring and insulation, and trusting brand and certification markings on the product since you can't open it without destroying it.
Clever!
And you'd need to remember to not use autonomous part of microcontroller (like a timer output) to implement it.
Considering the connected net is named "tip_control" I'd assume its PWM that is fed into MOSFET controlling the heater... and in vast majority of cases that PWM will happily run when core is hanged.
Looking at datasheet of the microcontroller PA6 does indeed go to tip_control and one of alternate functions is TIMER2_CH0, and at least glancing at code
/* enable TIMER1 - PWM control timing*/
timer_enable(TIMER1);
timer_enable(TIMER2);
https://github.com/Ralim/IronOS/blob/1fbcdcdf987a28541524e4f...
... timer_init(TIMER2, &timer_initpara);
/* CH0 configuration in PWM mode0 */
timer_channel_output_struct_para_init(&timer_ocintpara);
timer_ocintpara.outputstate = TIMER_CCX_ENABLE;
timer_ocintpara.outputnstate = TIMER_CCXN_DISABLE;
timer_ocintpara.ocpolarity = TIMER_OC_POLARITY_HIGH;
they are using it for PWM. The watchdog itself also appears to be enabled tho, so there is a chance it will kill itself the normal way
Some personally compelling reasons for myself as a guitarist:
1) With physical gear, I own the means of sound production. Less so for pedals that integrate closed computing elements into their circuits though, and even less if it has IOT crap (why??). Analog devices are generally best at this aspect.
2) Along those lines, longevity and repairability. Again this applies most strongly to analog pedals. I can keep using a well-designed pedal for decades, and keep it going with occasional repairs and maintenance. Digital modelers (including digital pedals to an extent), not so much, for a number of reasons.
3) In general, physical signal chain elements, particularly analog ones, strike me as more malleable as an end-user. I can do tweak the gain of individual stages, rework the inter-stage EQ and attenuation, etc. with a physical tube amp, and do similar things with analog pedals. Perhaps to a lesser extent with digital pedals too. I'm not aware of a modeling system with comparable flexibility, though I'd be interested in being proven wrong.
4) Some analog stuff, to my limited knowledge, is still difficult to model.
Why is this an issue? When was the last time you had digital electronics fail, and it wasn't a victim of the early 2000s capacitor plague (in which case, replacing the affected caps fixed it)? "Repairability" is vastly overrated: most electronics don't fail in the first place, and when they do, it's almost always electrolytic caps, and this affects both digital and analog circuits. There's nothing "unrepairable" about a digital circuit: it's not like a logic gate on your CPU is likely to fail.
>and even less if it has IOT crap (why??).
If you're referring to amps (like Fender Mustang series) that use your phone for the UI, that should be pretty obvious: the phone is an ubiquitous device that you can assume the customer owns, and provides a large touchscreen for controlling the amp remotely. It's not IOT; it's a Bluetooth connection. It's not necessary for using the amp, it's just an option, and a really helpful one when playing with effects settings, and much easier to use than the tiny LCD screen on the amp plus its jog wheel. Once the settings are done, you can assign settings to footpedal buttons and never mess with it again. With the 7-button footpedal, for instance, you can easily set it up with 5 different sound profiles you can easily switch between, with the other buttons you can switch between "banks" of 5 effects if you need more for one song/gig.
Also some say some quirks of analog designs are hard to replicate in simulation althought I haven't seen double blind tests of that so I'm mildly skeptical of that
However, if you don't need lots of gain a decent preamp can be built around the venerable 2N7000. Yes, that's a MOSFET, definitely not aimed at audio, but it's dirt cheap, available everywhere ...and noisy. But if you keep the gain to reasonable levels it works quite well.
Here's some info.
http://www.muzique.com/schem/mosfet.htm
(the entire site is worth bookmarking)
https://hackaday.com/2023/05/02/fet-fun-endeavors-together/#...