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brown_rb

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Posts posted by brown_rb

  1. 6 minutes ago, fozzybear said:

    Me to had to faff around different themes. To edit the program  source theme colours would be laborious and started to mess around with it but got completely confused what i was doing and trying to achieve so gave in

    Linux app updated to v007
    v007
    Change clNone attribute for all form captions/text to allow control by using themes

    Source code in zip file
    https://sourceforge.net/projects/esp32-dew-controller/files/Linux Apps/

    Let me know how it goes - you have to recompile source of course. If there are issues post a screenshot here or email me the screenshot and I will address it.

     

    Cheers

    Robert

    • Like 1
    • Thanks 1
  2. 10 hours ago, fozzybear said:

    dismantled my stripboard version I was not happy with it and ordered some boards from JLCPCB well 10 to be exact all for the price of 22 euros, Ordered 1st Nov and arrived today from China fast delivery. Now to get this little project under way nice looking board. Only problem is with the diodes with the larger dia legs.

    IMG_20201112_210751462.jpg

    Whatever you do, do not drill the PCB. This is a double sided board with plated through holes - drilling is a no no.

    The 10A10 is a biggie - 10A rated, I suggest filing down the leads with a small file to get to fit or first solder a 2p header in place then solder the 10A10 to the 2p header. Do not drill the PCB.

    The 1N5822 are schottky fast acting diodes. These help shunt the back emf produced during switching off the dew strap. Long leads act as inductors and try to maintain current flow when connected - so are very important. It is true that the MOSFET's do have this protection on chip but the 1N8552 IMHO are still needed. If they do not fit they will after a small amount of filing the leads

     

     

     

    • Like 2
    • Thanks 1
  3. The dew controller supports Bluetooth so no need for USB cable in this mode.

    And yes you can use a phone with the DewController BT app for android phones.

     

    Using separate ESP32's

    You would need 12V with mosfets to driver the output. So you end up with little esp32

    - 12V power needed - 3A capable wire needed

    - dew strap output - 2p RCA socket and wires needed

    - temp sensor input - 3p lead required

    So you wouldnt actuall save any cables or wires in my option.

    The dew controller as is now using mosfets really does not get very hot.connectActivity2.thumb.png.a6e83a4ba300ebe7819aa1ce254368cd.png

     

    • Like 1
  4. Looking good.

    Something that is not clear in the PDF. J7 is where you want to solder the ds18b20 transistor [without long leads and metal case - just a transistor type package all by itself] - the reason why it mounted on the board is to measure the pcb temperature and thus control the fan by turning the fan ON to cool the inside board temperature down if it gets too hot.

    I see you have already soldered J7 headers in place, I would suggest soldering the ds18b20 direct to these header pins.

     

    Cheers

    Robert

  5. The switches are ON OFF.

    You can use the 3p ones by using the center pin and one of the outside buttons as already pointed out. They are not momentary switches. The 3p ones use are ON OFF. You can use 2p on-off ones if you prefer.

    You really don't need them though as the software can do that already.

    The confusion is more about the fact that they are often mislabeled on ebay or aliexpress.

    • Like 1
    • Thanks 2
  6. The buzzer probably works better with 47 or 33 ohm resistor. the resistor is to try and limit the current draw to 20mA or less. I think from memory the buzzer draws about 30mA which is a little too big for the Arduino output pin to supply. Without the resistor, the Arduino output pin driving the resistor might be damaged over time.

    It also has to be a continuous tone buzzer - easy to test - if it sounds when you connect it to 5V then it is the right type - the longer lead is +ve. If it "pops" when 5v applied it is the wrong type.

    The buzzer I use for a POST indication. [Power On Systems Test]

    The buzzer sounds indicating that the arduino has been reset/started up. It turns off when the setup() is finished, the eeprom has been read and everything is initialized. So it tells me everything is working as it should be. If it stayed on then it indicated an issue in the setup. if it does not come on at all it indicates something is wrong - preventing the arduino from restarting. It has been very useful to me at times when making changes to the firmware.

    This is basically of copy of the old PC 386 POST routines I used when making embedded PC's.

    It is also used as a beep indicator for the Rotary Encoder option and to indicate when the position is set to 0 when both push buttons are pressed at the same time.

    Regards

    Robert

     

    Concerning cat5e not really suitable. We are talking 330mA *2 (2 coils on) or there abouts. Cat5e is not rated like this and the long cables will have too much voltage drop because the wire area is too low [voltage drop is relative to wire area - thicker wire = less voltage drop]. You are better going to thicker gauge wire. You want to keep the voltage drop low. Also cat5e connectors are no good, the contact surface area is low meaning the current flows through a small surface area - causing contact erosion. You need a good amount of surface area like a db9 connector or gx12 4p connector - it will not suffer from the contact erosion that a cat5e or rj45 connector will, hence last longer and perform better. hence a rs232 extension cable is a better bet.

     

  7. On 11/01/2020 at 07:24, JamesF said:

    And for the final bit of PCB soldering, the MOSFETs and voltage regulator.  The heatsinks I bought turned out to have small steel "legs" on when they arrived, which I didn't initially realise was the case.

    rbrown-dew-controller-39.jpg

    I assume they're there so they can be soldered to the PCB and stabilise the heatsink.  And perhaps to connect it to ground.  There's no place for them on the PCB though, so I snipped them off with the side cutters.

    rbrown-dew-controller-38.jpg

    Because there's not much room on the PCB for the heatsinks (some of the resistors prevent them from fitting flush with the PCB) I decided it was easier to put the whole thing together before soldering it into place.

    rbrown-dew-controller-40.jpg

    Even then it was easier to put some of them into the board at a slight angle to get sufficient clearance.  An alternative might be to just saw 3mm or 4mm off the bottom of each heatsink.  I don't think it would compromise their performance that much.  And again I held them in place with a blob of blutak whilst soldering.  And here they are, all done.

    rbrown-dew-controller-41.jpg

    To make much more progress I probably need the case printing, so I'll get that under way.  I'll also go over the back of the circuit board with a magnifying glass just to check there aren't any unintentional bridges in the soldering.  Then I'll plug in the Nano and at least see if it lights up and runs the default "blink" code ok.

    James

    James

    A user (Mario) who is following your build asked a question about the Mosfets. It looks like some of those Mosfets are the wrong way round? The double bars on the silk screen indicate the heat sink or metal part of the T)-220 package.

     

    Untitled.png

  8. 9 hours ago, Vox45 said:

    I own a NEMA 17 motor (17HD34008-22B) I did not know about this gearbox advantage, this model does not seem to have a gearbox.

    I will be using an RPI4 with a Waveshare Stepper Motor HAT. This is neat as I only have to provide 12V to the HAT for the motor and it also provide the 5V to the RPI, so only one power source for both. Someone wrote an INDI driver for this and what the driver does is stop on a full step.

    "only stop on full steps, it only uses microstepping to make things smoother and quieter. A stepper motor can't hold position at one of the microsteps without power applied, and even then, it's just an approximation. It can hold position at a full step even without power, which is what I do, I kill power to the motor when it isn't actively being driven."

    So that would mean that using a motor without a gearbox makes you lose 32 microsteps, maybe this is ok on a short focal refractor that has a larger Critical focus zone (CFZ) ... I need to dig deeper into this, I might have to buy a gearbox motor then...

    This is the thread on CN

    https://www.cloudynights.com/topic/688855-building-myself-a-stellarmate-gadget-any-advice/

    This is not correct. I must take issue with this. A NEMA motor, operated at full steps, CANNOT hold a position at a full step even without power. ONLY if it is a geared motor like a PG27. If it is a standard NEMA non geared motor, then it has insufficient holding torque for most "imaging" trains especially when pointing towards zenith [which must be the true test of holding power]

    regards

    Robert

    • Like 2
  9. Hi all
    I am not trying to confuse things as James posts are very good reading.

    I was asked recently about the possibility of adding a 4th channel to myDewController3. It turns out this can be done without much effort. If the FAN is used as a dew controller output this can be done with very minimal effort.

    The basics are
    1. Wire the FAN output J1 to a dew strap (via RCA connector)
    2. Remove the DS18B20 little transistor from J7 and wire J7 to a temperature probe jack (so an external temperature probe can be connected)
    3. Load some new 4CH firmware
    4. Control the new 4CH box with a new 4CH Windows app
    5. No need for RGB LED on J5

    With ventilation slots in the project box heat should not be a concern with the MOSFET design. I have done the new 4CH firmware and new 4CH Windows application.

    And now, back to James for progress updates.
     

    • Like 2
  10. I prefer the GX12 as they are solid and plenty of contact area to handle current. But not always suitable as you have pointed out.

    The issue with the recommended RJ connectors for the temperature probes comes down to crimping. Many uses find the wires of the temperature probe are difficult to insert to the crimp connector. This is true. But where there is a will there is a way.

    I find that the recent temperature probes I have purchased tend to have thicker gauge wire, making it next to impossible. But as I said, there is more than one way to *kill a cat.

    Another user gave me this tip - I take no credit for it - cut the temperature probe wires to the length of the crimp connector. Then strip about 5-7mm of bare wire. Lightly solder these to keep the thin strands of wire together, do not use much solder at all because you want this diameter to be smaller than that of the outer plastic sheath of the wire. Okay, so now you have small diameter which will slide through the connector and be able to be crimped. Just spread the wires out in correct orientation and insert into connector and crimp.

    Cheers

    Robert

     

    20190301_153056.jpg

    20190301_153149.jpg

    20190301_153351.jpg

    20190301_153532.jpg

    • Like 1
  11. Hi

    Nice work and easy to follow.

    Just a word about the 3p audio sockets/connectors. These were part of the original v2 controller. However, there are a number of issues.

    1. If you make a mistake and remove/connect with power on you can easily blow the digital pin on the Arduino as well as other power issues. Remember that when you pull it out (or insert) pins can get shorted, so its not a good connector to use when you have 5V and GND on two of the pins with a high likelihood of a short

    2. Even though the current is low, over time you can find that the pins and connectors "solder" themselves together due to the current flowing through them. And when you try to pull out a plug half of it ends up staying in the socket. The 3p audio connectors/sockets are not suitable for the current being drawn by the temperature probes.

     

    Regards

    Robert

    • Like 2
  12. Hi

    I believe users make a common mistake. They look at current and they say ok, I will select this stepper that has 1.6A current and use that on a drv8825 chip, because this stepper is cheaper and the drv8825 should handle that amount of current.

    What is forgotten or neglected to mention is that when a stepper actually steps, there are steps when BOTH coils are active at once, so the current drain can be 2x the stepper current. So instead of  a possible 1.6A max, it is actually 3.2A max.

    When using a PG27 rated at 0.4A, this would mean a maximum of 0.8A of current when both coils are active. This means that even with both coils active, the heat generated is still "warm" to the touch, the drv8825 is not overstressed, and everything can operate within tolerance.

    Regards

    Robert

  13. On 04/10/2019 at 20:07, Astro-Geek said:

    There's only one very minor thing that still intrigues me, when I test the manual hardware in/out buttons, the step position counter on the LCD display suddenly reverts to 0 after a dozen steps or so,  (with the LED lights flashing correctly).

    The position counter performs perfectly when controlled by the computer, with all the stepping increments, in and out, and the numeric step position is always mirrored correctly in the LCD window on the box.

     

    If this is happening please email me directly (address is in firmware file) so we can get to the bottom of this

    Regards

    Robert

  14. On 28/09/2019 at 08:46, Astro-Geek said:

    It still has step size set to 50 microns, which is the maximum with the firmware version on it (290 - the latest).

    If I could up it a bit, it would then be a good all-rounder for all of my scopes.  (maybe I could look through Robert's code, and find the range limiter ? )

    Version 291 in testing will increase this limit to 100.0

    https://www.dropbox.com/s/98taxxjlhocs158/Firmware%20myFP2%20291.zip?dl=0

    Cheers

    Robert

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