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Topic: Really universal soldering controller (Read 818293 times) previous topic - next topic

Re: Really universal soldering controller

Reply #4110
I used 4001 earlier, and it's not perfect. Since sparkybg has drawn the schematic diagram, why can't I try it? Is there a mistake?
Do not blame something,  which you don’t understand. First edition of the touch sensor was designed by me in my lab, which is full of cables, but does not have noise like that. You cannot compare circuit without any filter to the filtered one.
In fact, if you use C at inputs of the circuit, you connect in parallel to the thermo couple 200k + C(nF). For RF coming to the input it is 200k roughly – you violate the main temperature measurement.
I expect at input, sometimes to have 2000V static, rate you capacitor and diode in parallel at least to that.
Adding the C to the input, just prove the rest of the schematic does not work.
That was the reason filtering to be added after the IC, to keep High input impedance. Even the diode in parallel make it less.
So simple schematic but so many mistakes, BRAVO  !!!

Re: Really universal soldering controller

Reply #4111
Everyone can freely choose one or the other schematic, but it is good to be aware of the facts.

Re: Really universal soldering controller

Reply #4112
Everyone can freely choose one or the other schematic, but it is good to be aware of the facts.

I understand. You worked hard

Re: Really universal soldering controller

Reply #4113
In fact, if you use C at inputs of the circuit, you connect in parallel to the thermo couple 200k + C(nF). For RF coming to the input it is 200k roughly – you violate the main temperature measurement.
Not true:
1. 200k impedance at the input has practically no influence on temperature measurement of thermocouple with impedance of less than 1 ohm, even if it was 200k down to DC.
2. The input impedance is 200K only at high frequencies. At low frequencies it stays as it is in your circuit.
2. Even if the input impedance of a sensor is 2K for example, and the input impedance down to DC was 200k, the influence on it's reading would be 0.1%, which is, -0.45 degrees maximum.

So, forget about influence of 200k input impedance on temperature reading at all, even with 1000uF there.

I expect at input, sometimes to have 2000V static, rate you capacitor and diode in parallel at least to that.
Not true:
1. Ask yourself why there are no capacitors that are packed at factory in ESD packages, but in single plastic or paper strips. BINGO - they are not prone to ESD by a great extend, because they have low impedance at the the frequencies the ESD happens.
2. High voltage at input cannot happen when there's a capacitor exactly because the capacitor has low impedance at high frequencies.
3. High voltage at the input cannot happen even if there is no capacitor - the diode itself has leakage and capacitance, and reverse voltage barrier won't let voltages there higher then reverse breakdown voltage of the diode. And at the currents that flow with ESD cannot damage the 1N4007 diode and even 1N4148 diode when it is behind 200k resistor.

Adding the C to the input, just prove the rest of the schematic does not work.
Adding the C to the input has nothing to do with the rest of the schematic. I've posted the simulation results - all 3 variants are working equally, including yours. It just proves that in your lab there isn't high enough RFI to trigger it by touch, or the EARTH in you lab/controller is different.

That was the reason filtering to be added after the IC, to keep High input impedance. Even the diode in parallel make it less.
Wrong again:
1. Input impedance and input capacitance are NOT the same thing. When you add input capacitance, the input impedance stays the same at low frequencies and you lower it only at high frequencies.
2. The filtering at the input does just what we wanted from the very beginning - it suppresses the high frequencies at the input by being low impedance at these high frequencies. IMHO, it is better not to allow high frequencies to enter the circuit, then letting them in and fight them after this with more components. The high input impedance (eg. low input capacitance) at high frequencies is important at the input of oscilloscope for example. We don't want these on our circuit, so input capacitance is in fact a good thing in out case.
3. Your circuit have diodes in parallel too, and most likely even leakier. They are just inside the chip.
4. The only thing that need to be rated for high voltages is the 200k resistor, and this is true both for your and my schematic. This is why the resistor between GND and USBGND on the front board is so large - it's voltage rating.

So simple schematic but so many mistakes, BRAVO  !!!
Given the things I wrote above, don't be so extreme with your words. You don't like my circuit, I don't like yours, but that's the way it is. As I said there's no perfect circuits for anything, anywhere.

Re: Really universal soldering controller

Reply #4114
Minkok, I have zero issues on 245 and 210 using 4001,  I really believe it makes the cartridges last longer if you use the station daily.

Can there be any improvements?
There is always room but this small PCB 4001 does the job for me.

If anyone has better results using different schematic I would be interested to try.

Good job all

Tronix

Re: Really universal soldering controller

Reply #4115
minkok, here's what you have on 4001's inputs. LM339 does not have diode to ground, and that's why it is added externally.

So the real difference is... just one capacitor, and the input level at which you circuit triggers (maybe around 2.3V - it is not specified for 3.3V power), and 1.65V on mine. Replace  R3 on my schematic with 1k, end they will become the same on this also.

Re: Really universal soldering controller

Reply #4116
Minkok, I have zero issues on 245 and 210 using 4001,  I really believe it makes the cartridges last longer if you use the station daily.

Can there be any improvements?
There is always room but this small PCB 4001 does the job for me.
The initial design with the 4001 still works for me too. It's simple and very usable... even though i have the same behaviour lots of people had with (which is: touching the holder with my bare hands will be recognized as "iron-in-holder"... which i don't mind that much, since i usually do not touch the holder).

But: this is a very (VERY) small pcb. And size does matter (in this case), because i don't have THAT much space inside my holder. I was planning to modify the pcb a bit (meaning: adding connections for a tiny angled connector... and holes for surface mounted threaded standoffs, to mount it easier and more elegantly to my holder - which is now done so far by two small nuts glued to the pcb). So if it's similar in size with a more reliable behaviour (due to software filtering) i'm all for a tiny PIC-controlled solution like 'sparkybg' suggested.

Re: Really universal soldering controller

Reply #4117
Wrong again:
1. Input impedance and input capacitance are NOT the same thing. When you add input capacitance, the input impedance stays the same at low frequencies and you lower it only at high frequencies.
I am afraid you are wrong, "Input impedance and input capacitance are NOT the same thing", just impedance inluded all.
2. The filtering at the input does just what we wanted from the very beginning - it suppresses the high frequencies at the input by being low impedance at these high frequencies. IMHO, it is better not to allow high frequencies to enter the circuit, then letting them in and fight them after this with more components. The high input impedance (eg. low input capacitance) at high frequencies is important at the input of oscilloscope for example. We don't want these on our circuit, so input capacitance is in fact a good thing in out case.
As I said, if your sch. works, as is low pass, it wouldn't need any input C, it wll just reject them.
3. Your circuit have diodes in parallel too, and most likely even leakier. They are just inside the chip.
they are just for that point, ESD protection.
4. The only thing that need to be rated for high voltages is the 200k resistor, and this is true both for your and my schematic. This is why the resistor between GND and USBGND on the front board is so large - it's voltage rating.
I don't have components connected to GND at input except for ESD protection.

Re: Really universal soldering controller

Reply #4118
I want to say that I have a pile of 4001 thrown into the garbage can, because I have a lot of this project, and I also have many friends who use 4001. It has problems among most people, but only a few people can work

 

Re: Really universal soldering controller

Reply #4119
The initial design with the 4001 still works for me too. It's simple and very usable... even though i have the same behaviour lots of people had with (which is: touching the holder with my bare hands will be recognized as "iron-in-holder"... which i don't mind that much, since i usually do not touch the holder).

But: this is a very (VERY) small pcb. And size does matter (in this case), because i don't have THAT much space inside my holder. I was planning to modify the pcb a bit (meaning: adding connections for a tiny angled connector... and holes for surface mounted threaded standoffs, to mount it easier and more elegantly to my holder - which is now done so far by two small nuts glued to the pcb). So if it's similar in size with a more reliable behaviour (due to software filtering) i'm all for a tiny PIC-controlled solution like 'sparkybg' suggested.
Did you try the last V1.33? My intention was to be used inside station case , as it is in mine case.

Re: Really universal soldering controller

Reply #4120

And even a simpler circuit can be made with the smallest PIC12/PIC16, but it have to be programmed, like my optical sensor. Hard reject on 50Hz noise can be done much simpler with software than with hardware. Then you will have 2 resistors, 2 diodes, 2 capacitors, a MCU, and that's all.

I'm looking forward to this program, because there are many factors that I can't do without touch sleep. I have to use touch

Re: Really universal soldering controller

Reply #4121
I want to say that I have a pile of 4001 thrown into the garbage can, because I have a lot of this project, and I also have many friends who use 4001. It has problems among most people, but only a few people can work
You can just "add a C at input".  Who's care! ... What I mean is, Do not do that !!! There is latest revision.

Re: Really universal soldering controller

Reply #4122
All of them are 339 in the video. I'm still testing them. It's obvious that they are working normally now

https://youtu.be/_3DMU5OffdQ

Re: Really universal soldering controller

Reply #4123
You can just "add a C at input".  Who's care! ... What I mean is, Do not do that !!! There is latest revision.

I still look forward to sparkybg's MCU solution

Re: Really universal soldering controller

Reply #4124
I am afraid you are wrong, "Input impedance and input capacitance are NOT the same thing", just impedance inluded all.

Don't be afraid - simulate it. The capacitor makes input impedance frequency dependant - that's all. On DC the impedance stays 10M. It is simple math to calculate even without simulation, and the simple fact that the impedance at DC of a capacitor is infinity says more then enough for this, even without calculation.

And the diode on mine is the same overvoltage protection as in 4001, of which the ESD is just one of the many cases. Put a comparator with input diodes and it becomes just the same. LM339 does not have diode to GND inside - that's why it is outside.

As I said, if your sch. works, as is low pass, it wouldn't need any input C, it wll just reject them. they are just for that point

And as I said - without this capacitor, mine works (and donesn't work) just as much as yours. The simulations are posted back in the thread. You decided to add 10 more components, I decided to add a single capacitor. And it obviously works, as can be seen on the movie. And is confirmed by at least 2 users already. Which one is better or worse - let other people decide, with facts from the real life.

If you continue to insist that my design (with capacitor) does not work in cases when your design works, you will have to demonstrate such a case.

If you insist that my design with capacitor and diode can be damaged by ESD more easily than yours, you again will have to demonstrate such a case, or at least explain the exact mechanism of this to happen. Capacitors are not prone to ESD at high frequencies (where ESD happen), because they clamp it, and thay clamp it, because their impedance there is low - this is my explanation - let's hear yours.