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Topic: Really universal soldering controller (Read 773922 times) previous topic - next topic

Re: Really universal soldering controller

Reply #3420
In fact, I may build this one (IMHO, a better one in every possible aspect). Again starts swinging the output at around 5Hz.

Re: Really universal soldering controller

Reply #3421
In fact, I may build this one (IMHO, a better one in every possible aspect). Again starts swinging the output at around 5Hz.
Excellent, just look here and tell me where is the mistake? Defenetely no compare!

Re: Really universal soldering controller

Reply #3422
Conditions: Pen is in holder -input level Low - after NAND - High, to me is the same but NOR, Follow pick up pen with noise.

Re: Really universal soldering controller

Reply #3423
Excellent, just look here and tell me where is the mistake? Defenetely no compare!

Good, now make R1=470K and R6=470ohm on the second schematic. And there is no mosfet on my schematic. ;) Looks familiar?

This is how it looks with 50Hz on my last one (green is at second comparator's + input, yelllow is at the output):

Later I will put simulation on thw one with diodes - I forgot to save it, so I don't have it.




Re: Really universal soldering controller

Reply #3424
Good, now make R1=470K and R6=470ohm on the second schematic. And there is no mosfet on my schematic. ;) Looks familiar?
Count mosfet as your last NAND. Isn't the same? I am bored to fix your mistakes. Sorry!

Re: Really universal soldering controller

Reply #3425
Comparators has a couple of mV hysteresis in open loop configuration, so Schmitt gates are probably a better choice with slow transition signals.
And, definitely, regular gates can't be used with integrated signals.


Re: Really universal soldering controller

Reply #3427
Count mosfet as your last NAND. Isn't the same? I am bored to fix your mistakes. Sorry!

Here I simulated your and my 2 variants (with gates and with comparators). Please tell me the difference. On the input there is 0V for 0.25s (iron in holder), then 10V 50Hz sine wave (iron is out of the holder, plate touched with finger). The outputs of all 3 are absolutely the same.

BOM(Comparator) - 7 different parts
BOM(Gates) - 7 different parts
BOM(Your) - 9 different parts (10 if we count 100n capacitor that is not on the schematic)

So, why transistors?


Re: Really universal soldering controller

Reply #3428
Comparators has a couple of mV hysteresis in open loop configuration, so Schmitt gates are probably a better choice with slow transition signals.
And, definitely, regular gates can't be used with integrated signals.

Agreed, but... Comparators are much slower (at least 3 times slower than 4001, not to mention 74xx), and in front of the second comparator we have really large low-pass filter.

...and between SLEEP signal and the MCU there is also another 1.8k-100n low pass filter.

So I think it is irrelevant if they are Schmitt triggers or not. Moreover - comparator transition point is perfectly defined, which is much less defined in gates, and much more undefined for MOSFETs, so MOSFET will switch on very slowly, and gate threshold is highly temperature dependant on top of the fact that it is also not very well defined from part to part.

Re: Really universal soldering controller

Reply #3429
If in real design comparators wouldn't produce transition bursts due to noise or the noise will be filtered on the front board it doesn't matter  what to use, threshold level is not that important here.

Re: Really universal soldering controller

Reply #3430
If in real design comparators wouldn't produce transition bursts due to noise or the noise will be filtered on the front board it doesn't matter  what to use, threshold level is not that important here.

Yes, there are 2 low pass filters in the firmware also, despite the fact that the firmware reads this input 100 times a second, which again is kind of low pass filter. I am reading the buttons the same way - no problems with transitions on them also.

Don't get me wrong - I just asked why there are additional components on the board despite the fact that there are free gates in the IC doing nothing, which are perfectly OK to use instead of transistors. I never insisted that something does not work.

 

Re: Really universal soldering controller

Reply #3431
How does transient analysis look with 1M instead of 200K on mains earth connection?

Re: Really universal soldering controller

Reply #3432
They look the same, but this kind of things is pretty hard to model right so real life may give some surprises.

Re: Really universal soldering controller

Reply #3433
By the way I just found and corrected pretty nasty bug - the station hangs at 511 degrees and refuses to run and heat anything. Tomorrow a new firmware will be published with this corrected.

Re: Really universal soldering controller

Reply #3434
Where is the NAND on the input then?
My simulation is for 3.3V the same as real, models are for 5V design - thats mean omited