CFW for KSGER/Quicko STM32 Soldering Stations

[bhishmar]

What I would do is to add a signal mosfet at the input of the amp, shorting the input to ground until the input is ready.
The amp saturates with ~13mV input (250 gain).
Zeners and such won't help else than for protection.

Typically, No amount of signal tampering/shorting at the input of an OpAmp can prevent its saturation, especially at such high gains, unless otherwise you resort to specific negative feedback. 

But I have to respectfully disagree to the point that the Zener can only provide protection. Allow me to explain.

My suggestion (in above post #498) of a 2.7V Zener was not for device protection. Instead it is for clamping the output of the opamp  below (<=) 2.7V, and thereby prevent its output stage getting saturated, & creating all the extra recovery time delay issues.   This is achieved thru opamp negative feedback, by connecting this Zener btw its output-pin and its inverting-input pin, as shown in the figure attached below (Option-1, Zener-FB).  This is achieved with no sideeffect on the normal TC-amplifier (gain=250) action.
 
" alt="" class="bbc_img" />


Infact, I think your signal MOSFET solution also will be more effective,  if it is connected as negative feedback to opamp (fig Option-2), rather than simply shorting the input to Gnd.    It has the added benefit of giving this limiting at both polarities (+ & -).   But you have to select an  NMOS with <= 2.5V Vgs Threshold, when operating from +3.3V, since its source also will be raised up.

The option-1 negative feedback Zener will clamp (limit) the  opamp output, for +ve going input only. When the input signal goes negative (transient -ve spike) at the MOSFET power-off instant, the opamp ouput stage may still  be saturated in the –ve direction.  But since the opamp is powered with single supply, output is limited to zero.  The negative-feedback from reverse diode action of the zener-diode will not come into effect till Vin goes below -0.7V.  But still the opamp output stage will be saturated, creating recovery time delay I think.

But in both the above cases it has to be positively ensured that the presence of the device (Zener or Mosfet channel) across the opamp will be a complete insulator when Vin < 13mV (from TC), and so does not mess up the 250 gain of the opamp, in its normal TC-amplifier operation.

[cosmin1]

@cosmin1,
I have some questions to you, w.r.to your above post #403, (Dec-08), to start with.

1. The “V3.1S” firmware [“3.1Snew1.hex”, 157.48 KiB], you were testing,  Is it the one received from member “nkls” of the Russian Radiokot forum, which claims to have fixed the T12-BCM2 Tip Calibration Bug?

2. Does after flashing this “3.1Snew1.hex” firmware, the unit needs the “RG1” & “RG2” keys to be entered, for it to start working?

3. I have some confusion as to the exact T12-KSGER unit you have, & used for the above  3.1S test?
    Can you confirm whether this is as below:-

a)  “3.1S”  hardware black-controller PCB.   
b)  ARM-uC: STM32F 101RBT6.
c)  SysInfo Menu: [HWver 2.00, SWver 2.12].
d)  Categorized as “2.1S r3” by dreamcat4 (github doc)
e)  OLED: 1.3” 6-pin  128 x 64, SSH-1106, I2C-i/f ?
f)  Board Schematic as per “KSGER STM32 OLED-3_0 schematic rev1_cosmin_floobydust.pdf”,
     you posted in post-#430 here, dated Dec-12, 2020.

4. Finally, Why do you call it ver-3.1S, even though SysInfo-Menu says Hw-Ver 2.00?
    Is it because of any PCB silkscreen markings?  But I did not see any such markings in your posted photos earlier?

1. Yes, it's from Nikolai. He said all bugs are fixed in this firmware.
2. From what i remember, v.3 doesn't need activation.
3.
a, b) 3.1S marked black PCB with STM32F 103RBT6 and 2.1s r3 PCB without markings using STM32F 101RBT6 MCU, same schematic.
Difference is, STM32F 101RBT6 supports both v3.1S and v2.0 firmware. STM32F 103RBT6 only supports firmware v3.1S. However, some russians reports they are still using v2.0 firmware on this v3.1s board. Mine doesn't work.
c) Yes, before flashing, i had HWver 2.00, SWver 2.12. But the the available v2.0 or 2.1 firmwares does not work on the controller with STM32F 103RBT6.
d) Exactly. Difference from the marked v3.1S is as i said, the 101RBT6 MCU.
e) I have OLED: 1.3” 6-pin  128 x 64, SSD1306 and a 1.3” 6-pin  132 x 64 SH1106. 3.1S marked board uses the 1.3” 6-pin  128 x 64, SSD1306 and the image is shifted to the right. I ordered a 132 x 64 SH1106 display to replace it.
f) that schematic is the same for both black boards.

4. I call it v3.1 because it's marked like that. Don't know what v2.0 firmware did he used before, because now it only supports v3.1S firmware.


Same as v2.1s r3. Just the battery connector position is moved:

[DavidAlfa]

Now I understood your idea!
That's a very nice workaround indeed!

Bozog, can you test if and check if it improves the delay problem?

[Bozog]

Well I could, but is the opamp recovery time really a problem, from what I see it is fast <300us?

With the hakko tip the opamp output is 0v (for 200us) very soon after the heater switches off, and this I think is due to the heater coil negative voltage spike induced thermocouple error.

I need to put the oscilloscope on the heater output again with the 200ms firmware.

[bhishmar]

Now I understood your idea!
That's a very nice workaround indeed!

There is always a saying in electronics.  A para or a page of write-up can never defeat a simple circuit diagram.

‘Bozog’, if u are planning to test this, make sure the schottky-diode (D4) clamp at the + (non-inv) input is also  there.  (Fig-1a)
Why?

When this opamp works in Closed Loop-Negative-feedback mode (its normal mode), its output Vo = (Vi + Vz) = ClampVoltage [0.3V] + ZenerVoltage [2.7V]  = 3.0V (when Heater is ON)
[Vi is the opAmp input (inv) pin voltage.]

So for this Diode-clamp (D4) if you use any other diode, (i.e.  a 1N4148 [0.7v] or LED [1.8v]), the above sum will exceed +3.3V, which defeats the purpose, of keeping the opamp within negative-feedback linear region.

I will try to test a discrete 2.7V Zener in stand alone mode, to see how its Cut-in knee voltage behave.   The intention is to find out how much earlier it will start conducting before reaching 2.7V.   If the 2.7V Zener starts its knee before 2.25V, then the TC-amp gain will reduce  from 250, for higher temperature sensing near 450°C.

But we have good margin 2.7V- 2.25V = 0.45V, So I don’t expect any problem. Just for confidence.
2.25v is the opamp output corresponding to 450°C.

For this parameter/phenomenon (0.45v margin),  the additional schottky voltage +0.3V does not influence, since when voltage ‘Vin’ raises, so also Zener-Anode voltage at inv-inp pin-4, due to standard Opamp-virtual-Gnd phenomena.

[DavidAlfa]

It stranges me too that the big delay is caused by the amp... but who knows!

[bhishmar]

But is the opamp recovery time really a problem, from what I see it is fast <300us?

From the expanded view of your graph above,  the settling time from Heater-Off is nearly 500 to 600 µs.  But if you consider 90% of the final settled value, then this time is ~400 µs.  But this figure is prone to widely vary from unit to unit, depending on the following phenomena.

• The quality of the opamap device.
• The  amount of overstress, the opamps input & output stages are subjected to, based on the presence or absence of voltage-clamping/limiting devices.  This includes phase-inversion by some really bad opamps, as pointed out by floobydust.
• Speed of turn-ON & turn-OFF  of the power MOSFET depending on its gate driver circuit.

Regarding ‘3’, in the standard KSGER circuit this gate driver is  a simple transistor (or mosfet) pulled up to +24V thru “1K+2K” resistors combination.  This circuit can only provide a 24mA drive to the power  MOSFET “gate capacitance” & “gate charge”, which is inadequate & is causing its longer turnoff time.  That aspect at least is not attributable to the opamp recovery time, as seen from the graphs provided by floobydust in his post #472 (Dec-21).  Even the delays shown by him is not the full picture. To get that, the controller-heater-on/off command output signal (port-out) vs “heater” vs “opamp-out” is required.

A more professional MOSFET gate driver is a two-transistor push-pull drive, with 100Ω series resistor, similar to what “Russel McMohan” suggested in this article below:-
https://electronics.stackexchange.com/questions/31594/mosfet-when-can-we-not-assume-that-the-gate-current-is-0
(See attached circuit.)

Beware, I am NOT advocating here, the above circuit changes to everybody’s  KSGER hardware for David’s custom firmware.  It may be too complicated to do as a patchwork in the current KSGER controller board. (Unless otherwise a separate 2”x 2” PCB circuit is designed tobe housed inside the current unit. But as I understand, that is not the primary goal of the current proponents of this forum-post, and the project coordinated by dreamcat. ).

But the above Gate-driver design change is an apt candidate, if anybody is planning for developing an entirely new custom-board, along with David’s custom-firmware for T12, as is indicated by some discussions here earlier. (I think by Gandalf_Sr/floobydust/dreamcat…).
May be the 3.3V discrete regulator with heatsink, and the LC-filtered 3.3V to the opamp & ADC sections of STM-micro, as suggested by David,  can be candidates considered into such a PCB.

But changing the gate drive this way has advantages & disadvantages, to be considered by such ventures.
 
Positives:  MOSFET will Turn-Off fast (say ~10us), from the instant of Heater-Off command by controller firmware.  So the opamp input as well as output will settle earlier, to handle TC-voltage (21uV/°C). 

Negatives:  The noise spikes/transients created by the much faster & steeper MOSFET turnoff signals will we bigger & worse, if  not snubbed or clamped properly at the mosfet & opamp.

[totalnoob]

I thought that Dreamcat's project was twofold, 1 - document the changes to the KSGER hardware and CFW compatibility with the HW changes and 2 - to also develop an open source HW that is compatible with the CFW but is generally based on the KSGER HW, and overcomes the documented shortcomings of the KSGER HW and allows compatibility with T12, C245 and, at some point C210 handles/tips. In other words, the idea was to have a "next gen Unisolder" that was simplified to focus on compatibility between the three handles/tips I mentioned.  Generally, I believed that another factor for point #2 was to retrofit a KSGER station with the open source HW, although there was a short discussion of getting away from the form factor that KSGER (and the copies like Quicko) use for their stations.  This was why I pointed out in an earlier post that a company appears to have done something similar, although it was based on an STC mcu instead of the STM32.  The controller promises to be compatible with T12, C245 and C210 (with a 12V, 6A power supply, vs 24V power supply needed for the T12 and C245), but the seller has not answered my question whether the controller comes with firmware that allows you to select which handle you are using or if you need to specify it when you order it so that it comes with the correct firmware. 

(Note to Dreamcat, if I am wrong on any of what I believed you were doing, please feel free to correct.)

[Bozog]

But is the opamp recovery time really a problem, from what I see it is fast <300us?

From the expanded view of your graph above,  the settling time from Heater-Off is nearly 500 to 600 µs.  But if you consider 90% of the final settled value, then this time is ~400 µs.  But this figure is prone to widely vary from unit to unit, depending on the following phenomena.

• The quality of the opamap device.
• The  amount of overstress, the opamps input & output stages are subjected to, based on the presence or absence of voltage-clamping/limiting devices.  This includes phase-inversion by some really bad opamps, as pointed out by floobydust.
• Speed of turn-ON & turn-OFF  of the power MOSFET depending on its gate driver circuit.

Regarding ‘3’, in the standard KSGER circuit this gate driver is  a simple transistor (or mosfet) pulled up to +24V thru “1K+2K” resistors combination.  This circuit can only provide a 24mA drive to the power  MOSFET “gate capacitance” & “gate charge”, which is inadequate & is causing its longer turnoff time.  That aspect at least is not attributable to the opamp recovery time, as seen from the graphs provided by floobydust in his post #472 (Dec-21).  Even the delays shown by him is not the full picture. To get that, the controller-heater-on/off command output signal (port-out) vs “heater” vs “opamp-out” is required.

A more professional MOSFET gate driver is a two-transistor push-pull drive, with 100Ω series resistor, similar to what “Russel McMohan” suggested in this article below:-
https://electronics.stackexchange.com/questions/31594/mosfet-when-can-we-not-assume-that-the-gate-current-is-0
(See attached circuit.)

Beware, I am NOT advocating here, the above circuit changes to everybody’s  KSGER hardware for David’s custom firmware.  It may be too complicated to do as a patchwork in the current KSGER controller board. (Unless otherwise a separate 2”x 2” PCB circuit is designed tobe housed inside the current unit. But as I understand, that is not the primary goal of the current proponents of this forum-post, and the project coordinated by dreamcat. ).

But the above Gate-driver design change is an apt candidate, if anybody is planning for developing an entirely new custom-board, along with David’s custom-firmware for T12, as is indicated by some discussions here earlier. (I think by Gandalf_Sr/floobydust/dreamcat…).
May be the 3.3V discrete regulator with heatsink, and the LC-filtered 3.3V to the opamp & ADC sections of STM-micro, as suggested by David,  can be candidates considered into such a PCB.

But changing the gate drive this way has advantages & disadvantages, to be considered by such ventures.
 
Positives:  MOSFET will Turn-Off fast (say ~10us), from the instant of Heater-Off command by controller firmware.  So the opamp input as well as output will settle earlier, to handle TC-voltage (21uV/°C). 

Negatives:  The noise spikes/transients created by the much faster & steeper MOSFET turnoff signals will we bigger & worse, if  not snubbed or clamped properly at the mosfet & opamp.

I don't believe the recovery we are seeing here is the opamp recovering from saturation, moreso it is the thermocouple recovering from the back emf from the heater coil, I will try to capture this on the 'scope. Therefore if anything we need a slower turn off to dampen the transient.

[Bozog]

Ok here is a couple of screenshots from across the heater, so opamp input, not too great because the scope didn't like the vertical turned up any higher with 25v peak.

1. I think we can see the opamp input is below 0v for around 200us, which would explain the output being at 0v for 200us
2. Here it doesn't look like the input settles for around 10ms

[Il_Marco]

I thought that Dreamcat's project was twofold, 1 - document the changes to the KSGER hardware and CFW compatibility with the HW changes and 2 - to also develop an open source HW that is compatible with the CFW but is generally based on the KSGER HW, and overcomes the documented shortcomings of the KSGER HW and allows compatibility with T12, C245 and, at some point C210 handles/tips. In other words, the idea was to have a "next gen Unisolder" that was simplified to focus on compatibility between the three handles/tips I mentioned.  Generally, I believed that another factor for point #2 was to retrofit a KSGER station with the open source HW, although there was a short discussion of getting away from the form factor that KSGER (and the copies like Quicko) use for their stations.  This was why I pointed out in an earlier post that a company appears to have done something similar, although it was based on an STC mcu instead of the STM32.  The controller promises to be compatible with T12, C245 and C210 (with a 12V, 6A power supply, vs 24V power supply needed for the T12 and C245), but the seller has not answered my question whether the controller comes with firmware that allows you to select which handle you are using or if you need to specify it when you order it so that it comes with the correct firmware. 

(Note to Dreamcat, if I am wrong on any of what I believed you were doing, please feel free to correct.)

About the new STC board on Aliexpress that should be compatible with T12,T245 and T210 here is what I understood about it, but I could be wrong:

1- you have to choose the first one (2€ more expensive)  to have the universal one, the only one that specify T245 and T210 compatibility (I think that the only difference is the software where you can select 245 in some menu)


2- the type of handle you are using is also detected by the ID input pin that is nothing different from the NTC input of Ksger boards. They explain in some photos how to connect different handles stating that wrong writing can burn your tip.

T12 handle / 10K NTC between ID and OUT-
T245 handle / ID shorted to OUT-
T210 handke / ID open

Something similar was proposed some posts ago in this thread.

3- T245 handle requires 24V 8A PSU, otherwise they say the unit will blink on and off by obvious power supply problems damaging the board (maybe in CWF we should avoid this by checking at power on the maximum PWM the unit would provide by probing +24V/11 input so that in won't go too low? At the cost of longer time to get to SET temperature of course).
T210 handle requires 12V 6A PSU

4- New input added to this unit is HR (not in GX12 connector but a pad on the PCB). This input is a pull upped and protected input that should be externally connected to the handle stand so that it would go to OUT- when you put your handle in the stand. This is the way JBC handle goes in standby. Anyway some menu would allow you to still use vibration or mercury switch for T245 and T210 standby or HR for T12 standby.

It seems to me that this new PCB has nothing that can't be done on Ksger unit by software and small PCB mods.

[cosmin1]

Don't bother with power supplies. I tested the T245 tip with KSGER controller on both 24V 4,5A and 6A power supplies. Both working fine.
Just on 4,5A board i replaced the 400V 2x22uF capacitors with 2x47uF for better stability. Maybe it works fine with standard capacitors too, didn't test it.

[bhishmar]

I don't believe the recovery we are seeing here is the opamp recovering from saturation, more so it is the thermocouple recovering from the back emf from the heater coil,….

it is the thermocouple recovering from the "back emf" from the heater coil  !!?

The real physical phenomenon involved in the generation of emf (voltage) at a ThermoCouple Junction, is the “SeeBeck effect”. 

But in your comment, what does “recovering from back-emf means”?  Are you referring to the opposite (corollary) effect of “SeeBeck effect”,  termed “Peltier effect”?    “Peltier effect” states that when a current is forced thru a Thermocouple junction, heat-energy is transferred from the “Hot-Junction” towards  the “Cold Junction”.  Mind you, this is not by joules heat transfer.

If by “back-emf” you are referring to the above “Peltier effect”, you may well be correct, since the heat energy transfer from hot to cold junction by the Peltier effect, in effect reduces the thermal gradient, by raising the cold-junction temperature. 

If indeed this is true and others here also agree to this, then it is all the more required that David or anybody’s firmware sampling the Thermocouple emf has to do it as late as possible, meaning just before putting ON heater.  Or at least well late in the cycle, when the thermal-imbalance of this  “effect” dies down, significantly. In effect you are giving a delay for the normal conductive heat transfer to predominate over the Peltier result.

The ”Peltier effect” is well documented and it is within the trio of  “ThermoElectric effect” (Seebeck, Peltier, & Johnson effects). May be other’s here can comment whether this Peltier effect is relevant, when T12 heater coil is heated,  and this is indeed what is happening.

https://en.wikipedia.org/wiki/Thermoelectric_effect#Peltier_effect
https://en.wikipedia.org/wiki/Thermoelectric_effect#Seebeck_effect

Location of EMF generated in a ThermoCouple
One associated fact: It is a common misconception that the location of the EMF (voltage)  generated by a Thermocouple is only at the Hot-Junction.   But in reality, it is not so.  As per the SeeBeck effect, this emf generation is spread out all over the entire length, of the two conductors (with dissimilar materials), from Hot-Junction to Cold-Junction.  That is, the entire portion of these two conductors which experiences different temperatures (or a thermal gradient) contribute towards generating this ThermoCouple voltage. (Ref: fig-1: Std ThermoCouple Circuit)


Many members here (including me) had this misconception earlier, since I had no well defined notion about ThermoCouple Seebeck effect, until I refreshed the material and researched the topic in detail.  But this misconception, screws up your rationale & logic, when thinking about the physical phenomena happening within the Tip.

In the above fig-1 (Std-Thermocouple),  both the Red & Yellow conductors from Hot-Junction (@Tsense °C) to the Cold-Junction (@Tref °C), contribute towards these EMF generation. Finally the differential voltage is fed to the sense-amplifier at the instrumentation block (typically opamp).  In fact if there is a further temperature difference between the Cold-Junction (@ Tref °C), & the Instrumentation-amp (@Tmeter °C),  (meaning Tref ≠ Tmeter) in the above figure, then both the (+ve & -ve) Copper wires connecting them will also generate an EMF, as well. But since both these wires are of same material “Copper” (NOT dissimilar materials), the emf’s generated in both the +ve & -ve wires will of the same amplitude and, so will cancel out.

In the special case of T12 (& similar) cartridges, one of this conductor (+ve) is the one joining to the Heater-Coil in series.   The other conductor  (with dissimilar material) is the –ve conductor, the end of which goes directly to the hot-junction located at the tip of the cartridge.   For T12 the cold-junction is, the dual ”terminal-contacts”  at the rear-end of the cartridge, where they meet the copper conductors from the handle-wiring. 

I hope this discussion above puts to rest categorically, the confusion and questions about where the “Cold Junction” is located in the T12 unit (Handle or MCU etc).  Refer to fig-2a & 2b  below for clarity on the above discussion with regard to T12 & similar cartridges.  Fig-2a & 2b attached below.


ThermoCouple Type of T12:  K, N, C ?
There was a question about what is the Thermocouple type (“K”, “N”, or “C”), the T12 cartridge has?  But the measured 21µV/°C is not matching neither of these std-types.  The reason is that this is not a standard thermocouple. From fig-2a,b it is clear that, the conductor from the Cold-Junction (+ve terminal) to the Hot-Junction, is itself made up of two type of materials.  Probably the conductor starting from +ve terminal is “chromel”, which joins to the heater coil, which is made of probably Nichrome.  The conductor from the Cold-Junction (–ve terminal) to the Hot-junction may be made of “alumel”.  So its thermal-EMF characteristics may be different.  This para (about materials) is fully speculation from my part, and not based on any hard facts, but it gives an answer for the possible mismatch from the known Std-Thermocouple types, in terms of EMF/°C characteristics.

I don't believe the recovery we are seeing here is the opamp recovering from saturation, more so it is the thermocouple recovering from the back emf from the heater coil,….

Now coming back to “Bozog’s” comment, the extended time (~400µs) for which a reduced voltage is seen at the opamp output may be the combined effect, of both opamp recovery & the above cooling by Peltier effect. We cannot separate out the effects in the visualized waveform.

Finally one more point, to see the full effects  of the mosfet turn-off delay, opamp recovery delay etc, & characterize it more clearly, we may need all three following graphs in the same time-line. (1. Mosfet Turn-off command by controller (port output).  2. Heater Voltage & Opamp-in,  3. Opamp-out ).  If not possible  two each in two separate graphs.

[Bozog]

Wow, that is an extensive reply!

I'm thinking just some residual negative voltage in the heater coil offsetting the thermocouple output.

To be honest, I think you're looking far too hard at the hardware side of this - it is not some precision differential instrumentation amplifier, it is 1 up from the cheapest of the cheap Chinese hardware with a few software tricks to make it look like it is working properly.

In my opinion, the hardware is what it is, if it needs a capacitor here or a diode there then fine, but anything more than that needs accounting for in the software.

For example the unisolder, which has much more comprehensive hardware and a proper differential amp, still uses wave shaping to filter out the inductive peaks from series sensor signal.

[bhishmar]

Wow, that is an extensive reply!

Well the first section was only really in  reply to your comment.

The next two sections (about ThermoCouple EMF location, & Type of T12 ThermoCouple)  were some general information about Thermocouples specific about T12, where I had seen some discussions here in these forums, but no definite answers. I was only trying to clear the air about some intriguing questions.

Regarding looking hard on the hardware or the system as a whole, hey that is what probably the Hakko Japanese have done during their original design. But it is proprietary info.

Chinese have simply copied like they always do.
But the difference here is that they built a simple copyable or customizable & cheaper STM based hardware, on a platform of the copied T12 Tips, which has the potential to perform excellent, which is why it caught on.

But generally the more info we have, on the system,  the more it makes the customized software & hardware better.  I mean ironing out the residual faults or deficiencies, by whomsoever have the time, patience & necessary skills. I am only trying my own two bits,  to help the community here, in the hope that someday a better CFW & better hardware emerge.

[Bozog]

I agree and I was not having a dig, and like I say sure if we can add a zener to improve performance then fine, but then we are talking additional FETs controlled by the microcontroller which is likely beyond the scope of many hobbyists who want better performance from a custom firmware.

Anyways some more screenies for you, first 3 are opamp output vs stm32 command, second 3 are opamp input vs stm32 command.

These are taken directly from PB7 so of course account for the switching time of FET driving transistor Q1 too.

[DavidAlfa]

It isn't a switching speed issue. Or It doesn't look like.
30uS turn-off time is not the fastest but is ok for this application.
bhishmar, by back emf, we refer to the inductive spike when the power is suddenly cut off.
The heater and the wires have some inductance, I guess specially the heater since it's it's basically a wire rolled up.
See the waveforms. In a pure resistive load, the voltage would drop cleanly.
But here ir drops below 0... And It takes a while to recover.

Bozog, is that the chinese tip? Seems much faster....

[Bozog]

This is the hakko tip, you can see in the first shot there is some error even upto around 100ms although it is negligible after 40ish

[bhishmar]

Some more screenies for you,
first 3 are opamp output vs stm32 command,
second 3 are opamp input vs stm32 command.

Excellent Graphs, Bozog. 
Timing figures on these graphs summarized into a Table below.



Can u give some details on your Unit & Controller Board (used for above graphs for record.)

1. Front-Panel Label, Name, or Purchase Website claimed name
2. Controller Board silk screen Ver, & PCB Color.
3. Board Classification by dreamcat (github doc)
4. Sysinfo Menu [HwVer, SwVer] of original firmware.
5. STM Micro Number: “STM32F072C8T6” ? same as DavidAlfa?

6. Firmware Version used for above Test Graphs ?

These are taken directly from PB7 so of course account for the switching time of FET driving transistor Q1 too.

I have  a feeling that, the extra timing of 6.9 µs from Port Command to Heater voltage Low going transition, is more due to the PowerMosfet gate charge  removal delay. Anyway the figures being much  less than the final settling delay, it does not matter much.

Can somebody else verify the timing figures, I intepreted from graphs to above Table?
Especially the 7.2ms & 91 ms figures!  They seem to be too high!!

[bhishmar]

Can somebody else verify the timing figures, I intepreted from graphs to above Table?
Especially the 7.2ms & 91 ms figures!  They seem to be too high!!

There is some mystery with these high timing figures, for the heater-voltage and opamp-ouputs to settle to saner figures.
I am also not sure whether these high values can be attributed to opamp recovery times.

Typically any opamp if saturated, takes some time to recover.  But once the input conditions contributing to the overstress and saturation is removed, it has to come out of it, within some reasonable time (I think typically 10’s of µs, to may be 100’s of µs), depending upon the quality of the opamp.  After all, if input stress is removed, it is the time constants within the chip/die with built-in caps, which cannot exceed few 10’s or 100’s of  pfs.   I cannot imagine these running to several 10’s of milliseconds, as is seen here.

Well I don’t know even the no-name opamps the Chinese put in there will do these trickery! Who knows? 

[jesusvallejo]

Today i erased the flash by mistake on my quicko    , so if you want i am ready to test some code. for the record i own another quicko , the pcb is exactly the same but the mcu, in the working one there is an stm32f072(as davidAlpha build) and the one that i erased is a cheap chinese clone of an stm32f103(also i cant find stm32f072 at a reasonable price). So there are two versions of the quicko t12 stm32 ,both of them report/ed HW:v3.1 and SW:7.1M, also have tried building the 103 version with the 072 .ioc , as the micro is the 103 but pcb layout is as on the quicko 072 but no luck, what should i do? thanks

[cosmin1]

Do you have some pictures with your erased board?

[Bozog]

1. Front-Panel Label, Name, or Purchase Website claimed name
2. Controller Board silk screen Ver, & PCB Color.
3. Board Classification by dreamcat (github doc)
4. Sysinfo Menu [HwVer, SwVer] of original firmware.
5. STM Micro Number: “STM32F072C8T6” ? same as DavidAlfa?
6. Firmware Version used for above Test Graphs ?

1. Quicko T12
2. Board "OLED-HT-V3.4" colour green
3. Not sure this board is there?
4. No longer have OFW
5. STM32F072CBT6
6. https://www.eevblog.com/forum/reviews/stm32-oled-digital-soldering-station-for-t12-handle/msg3380238/#msg3380238 - running a 200/40ms cycle

[jesusvallejo]

yes here you go

[bhishmar]

@Bozog: A few qns?

6. https://www.eevblog.com/forum/reviews/stm32-oled-digital-soldering-station-for-t12-handle/msg3380238/#msg3380238 - running a 200/40ms cycle

In the above referred post, you reported that (with PWM-peroid= 200ms, ADC delay= 40ms),  the Hakko Tips are performing well (i.e. maintaining a stable closed loop temperature), both at 330°C & 150°C set temperatures.

I am assuming the following facts also. Please confirm or contradict. Due to brevity of your earlier posts I was not able to follow certain things, or I was a little slow.

• Hakko Tips were working well with period=200ms, & delay = 40 ms now.
• Upto what reduced delay value was the performance reasonable for Hakko-Tips?
• Your T12-clone Tips, how do they perform, comparatively, w.r.to above questions (adc-delays)?
• Both your Hakko & Clone Tips were performing bad (NOT maintaining temperature) with the original Quicko firmware (OFW)?

Finally it was reported by many in these forums & also the sellers (Quicko & Ksger), that the Chinese T12 controller Units cannot maintain stabilized temperature with brand new tips.  The Temperature readings will fluctuate wildly & dance around a lot, when brand new Tips are used in such Units. This problem will go away automatically after a burn-in period,  when the Tip is allowed to dwell at a temperature of ≈ 300°C continuously for 5-10 minutes.

This phenomenon was reported my many, mainly for T12-clone Tips.  Not clear about Hakko Tips, with Chinese Controller.  Hakko Tips with Hakko-controller, nonbody has reported any issues such.

The reason quoted by some experts (including Johnny B Good) is as follows:-
( I have modified and expanded on his words here)

There will be some residual moisture is trapped in the  ceramic (mineral insulation) filling of these T12 cartridge tips around the thermocouple sensor, and heater coil, in all brand new Tips.  When you pass a DC electrical current thru the cartridge Tip terminals, the potential difference across the heater coil, or any segment of the wires, embedded in these ceramic filling, will cause  electrochemical & galvanic reactions since the trapped moisture acts as an electrolyte, and the embedded wires acts as electrodes.  This process will create some galvanic potential across these segment of wires which may be very weak, say few microvolts.

But the emf generated at the thermocouple is also a weak signal, a few microvolts.  So the galvanic potential created by above electrochemical process will totally mess up the sensor readings, which affects the thermal control, manifesting as dancing & bouncing  temperature figures for first 5-10 minutes. Once the generated heat, evaporates and clears the moisture completely, this problem vanishes.

https://www.eevblog.com/forum/reviews/ksger-t12-tip-selection/msg3346456/#msg3346456

5. My Question to you:
5a. Did you experience such a phenomenon with your T12-clone tips, in the original Quicko firmware?
5b. Did you experience such a phenomenon with your Hakko tips,  in the Quicko-T12 Unit with the original Quicko firmware?

5c. Or even after 10-15 minutes of initial heating @ >= 300°C, the Quicko Unit was not able to stably maintain set temperature, with both Clone & Hakko T12 Tips?


Incidentally to complete the earlier discussion, “Johny B Good” postulates a related aspect of the earlier issue in his post, which I also agree completely.

The best way to burn-in the T12-Tips is to power them externally (Stand-alone) with an AC voltage of ≈ 8V from a stepdown transformer.  8V is selected for approx. 10% of power  (8v/24v)^2 = 0.11.  Better to monitor the Tip temperature with a FG-100 sensor, and adjust AC voltage initially, so that you won’t exceed 300°C, in this open loop powering mode. Typically 7V to 10V ac, may be required to achieve 300°C Tip temperature in this open-loop mode.

Why AC?  Initial DC powering has a potential to create galvanic corrosion at the sensor junction (hot-junction) as well as the junction where the +ve terminal meets the heater coil, till the moisture is driven away.  This is  good  bad for the long life of the cartridges ( AC- burn-in improves service life).