PC controlled Flat Panel

[garymck]

Hi,

have just built an Arduino / PC controlled flat pane. Used one of these:

https://www.ebay.com.au/itm/A3-LED-Light-Box-Tracing-Board-Art-Design-Stencil-Drawing-Thin-Pad-Copy-Lightbox/131665998505?hash=item1ea7e7b2a9:g: HKwAAOSwt09bMJSy:rk:3:pf:0

Thread here:

https://www.cloudynights.com/topic/536533-diy-alnitak-flat-panel/

Arduino sketch here:

https://github.com/jwellman80/ArduinoLightbox

Can be controlled by Sequence Generator Pro (select Alnitak) or Voyager (select Arduino)

Auto flats here I come!

cheers
Gary

[multiweb]

Can you change the brightness of the panel as well?

[garymck]

Yes - SGP has a slider that gives 256 levels of brightness. Trying out Voyager tonite to confirm it does as well..
Gary

[multiweb]

That's pretty cool. I have the same panel but have to hold the power button to dim to the required brightness.
PS: ha I just noticed the power plug is a DIN type plug. I have a mini USB port so it probably works differently although the panel looks exactly the same cosmetically.

[garymck]

You have to take off the back and alter the wiring. The internal circuitry is rendered obsolete. The arduino uno provides PWM power to control the light level. The uno is in turn controlled by SGP or Voyager such that automated flats can be taken as part of an imaging sequence.

Gary

[multiweb]

Good stuff. :thumbsup:

[mswhin63]

I have concerns regarding PWM controllers in Astro stuff. Capturing lights are taken on high shutter speeds and could image during a off state of the PWM signal. It may or may not be an issue just a thought.
Really the better option would be current set for light level so that the LED are on continuously.

[garymck]

Flats are normally at least a couple of seconds long, taken with a very dim panel, so not an issue....

Gary

[jwoody]

Hello Gary
Did you use the TIP 3055 transistor or something else?
Thanks
Jeremy

[garymck]

Used a TIP35C picked up in error from Jaycar :-) wiring was the same....(but 25 amp capacity is a bit of overkill)

Beware the schematic early in the thread on CN - it is wrong and will kill an UNO. Read post number 5 - I wired it up per the written instructions here.

I believe a corrected schematic was posted later in the thread.

Gary

PS It is really cool watching Voyager change the light level until exposures reach the target ADU

[jwoody]

Cheers, thank you

[RobF]

Thanks guys. Looks like there should be no reason this couldn't replace the manual PWM controller I'm using with my 12V more traditional box-shaped LED lightbox.

Its surprising how much time you can spend on a good night, or early in the AM after a long session, trying to get good flats - particularly if have been shooting NB with LRGB (huge differences in light output required). The naughty solution is just not shoot them - which of course reduces quality of the final data.

Currently image through Sequence Generator so its tantalizing how close automated flats could be. Love how arduino etc are making electronic solutions more accessible to amateurs!

[RobF]

Just reporting back - managed to successfully build an arduino "alnitak" clone for my LED lightbox, again using the Cloudy Night thread listed above.

Parts purchased included:

- Arduino Uno https://www.ebay.com.au/itm/Arduino-Compatible-Uno-R3-ATMega328P-USB-Cable-AUPost-Shipping/182711179885?ssPageName=STRK%3AMEBI DX%3AIT&_trksid=p2060353.m2749.l2649

- IRF640N mosfet(s) https://www.ebay.com.au/itm/10PCS-New-IRF640-IRF640N-Power-mosfet-18A-200V-TO-220-IO/283453499157?ssPageName=STRK%3AMEBI DX%3AIT&_trksid=p2060353.m2749.l2649

- 100 ohm resistor(s) https://www.ebay.com.au/itm/CR25-0-25W-100-Ohm-100R-Carbon-Film-Resistor-25-Pieces/261491906850?ssPageName=STRK%3AMEBI DX%3AIT&_trksid=p2060353.m2749.l2649

- enclosure for Arduino mega (black) https://www.ebay.com.au/itm/ABS-Circuit-Board-Protector-Shell-Case-for-Arduino-Mega-2560-Mega-2560-R3/163770176675?hash=item26217694a3:m: mpXar_o0nkfKFMPYJH-1TfA

- Single mountable RCA plug (Jaycar)


I'm using the Arduino project code from late in the CN thread, which uses a different pin on the Uno (pin 11) and slightly modified PWM timer code (faster pulses to avoid artefacts on flats exposures).

The Mega project box nicely holds the Uno (mounting screw positions are seamless as are the USB and 12V power sockets) along with leaving a bit of space and screw mount for the mounting of the mosfet, as per picture below from CN thread.

Works seamlessly in SGP using 12V in on the Arduino and single USB plug. Very happy so far.

[The_bluester]

I have been meaning to look into building one myself. Flats for my ED72 I have been able to do with a graphics tablet I have lying around but it is not big enough for the SCT. I resorted to sky flats but to get the ADC I wanted at the longer exposure times that make an ASI294 behave it was into twilight and the ADU values changed by a lot over the run of flats. Like 30,000 to 15,000. The A2 panels would more than cover my SCT.

[RobF]

If you read through that full Cloudy Nights thread, it sounds like the trick with flat panels is finding one with a voltage you can supply easily enough, but also able to continue functioning as you pulse or vary input voltage.

I have a friend thinking of doing similar but large enough for RC12.

Would appreciate any comments from those that might have done it already and have a panel to recommend....


No reason can't build a more traditional LED light box for large scope - ends up bit deeper for decent light difusion versus flat panel though of course....

[The_bluester]

The advantage I see to something like the A2 tracing panel is in an obs it would be able to be mounted for use with my SCT, and anything smaller, given I do plan to build an obs of some description soon. The other idea I had tossed about was building one that was on a motorised arm so it could double as an objective cap so shooting flats would become a matter of parking the scope, closing the cap then switching it on and flat framing away.

[RobF]

Agree first is what people with bigger scopes tend to do for automation and convenience in observatories.

Have seen the latter as a DIY project at astrofest with the light panel on flip/flop actuated scope cover.

[kamayok3]

Hi all,

Looks like the Alnitak already changed their coding. After loading the firmware into my Leonardo board, Nina and SGpro cant connect to it. Sadly I am not a coding guy. Really need a savior now.

Regards,
Tom

[RobF]

Hi Tom

Does it work just plugged into your PC, without any Astrophotography software running? You should be able to vary the brightness manually from the Arduino environment?

I've never used Nina sorry - only SGP....

[kamayok3]

Yes, I managed to turn ON/OFF and vary the brightness from IDE Serial monitor.

[garymck]

Have you tried using an UNO board, the Leonardo board is not t the same, and the Uno code will not work n it.

Gary

[peter_4059]

I put one of these together this afternoon. It turns out Jaycar has a 24V 5A MOS Driver Module (XC-4488) made to work with Arduino. This makes the wiring pretty simple. I've assembled everything temporarily and tested it with the SGP code posted on Cloudy Nights. It's all working fine with my LED light box so next step is to get a box for the electronics.

[RobF]

B'ah - you can't put it together in an afternoon and make it look professional! What about wires hanging out of bread boards and your son hold a couple of wires together to test the circuit dammit! :D

[Astroman]

Awesome thread, I am planning on building this also, once I get my new observatory sorted, it will be remotely operated from about 120km away, so I was after a DIY solution for flats. I had seen the CN thread before and bought the TIP 3055's incase. I have the UNO here also, well a clone, which works the same. I plan on using Voyager for the control of it.

[peter_4059]

You should have seen the other end of the black wire...that had all sorts of dodgy things going on to make the light box connection. I hate soldering wires on 2.3mm jack plugs.

[The_bluester]

I take it from what others seem to be using there is no issue in using the "Uno Compatible" knock off boards? Looking on fleabay it is hard to find a real Arduino board. I was gifted a preloaded credit card for Christmas to build myself a flat panel, so it is time to get on with the job. I ebayed an A2 panel (To be sure it will cover any scope I am likely to ever use it with) from the same seller as Gary did on starting this thread.

It will certainly be easier than my current routine which is a graphics tablet balanced on top of the scope and using Teamviewer to remote in to the PC it is connected to to edit a JPG image by varying the density of the "grey" image that I display on the panel.

[Bart]

Hiya.


So this isn't mounted to the scope like a flip flat? It is bolted to the wall in line with the storage position of the scope or a defined position to capture flats?


Can we have some comprehnsive pics please as I have a remote observatory?


Thanks.

[peter_4059]

I'm using Jaycar Uno boards and they are working fine.



I'm using it with my normal light box but it could be used with a EL panel bolted to the wall. I don't think anyone in this thread has made the servo motor to open a panel attached to the end of the scope however I have seen a home made one like that at astrofest.... here is the thread:

http://www.iceinspace.com.au/forum/showthread.php?t=173190&highlight=flip+flat

[The_bluester]

Well that makes it easy, I expected that they should work, and the compats are so cheap I could afford to make a couple of them. I am a bit tempted to do that actually. For some time I will be imaging with a small scope and no obs so I could start with a small tracing panel as well and build it into a slip on light box to be able to be used in daylight.

[Astroman]

Hi Peter,

Just purchased the little 24v 5A Mos board from jaycar and wondered how you have the lightbox wired in. Is this between the 12v supply and light box? With the other three wires off to the Arduino?

[peter_4059]

I've got the three control wires connected to the Arduino:
SIG to pin 3
VCC to 5V
GND to GND

On the XC-4488 breakout board there are two blue terminal blocks:

One is for the 12 V supply:
VIN & GND


and the other connects to the light box:
V+ and V-

[Astroman]

Thanks Peter, exactly what I thought. So you are using Pin 3 for your PWM signal, is that using the updated code from CN? The one with the added better timing for the Pulse width that kidogofoto had put up?

[peter_4059]

Yes I'm using the code with the different pwm timing. You can choose which pwm pin to use and in my case this arduino is only performing one function so pin 3 is what I went with. I've posted a copy of my code in the attached TXT file.

[The_bluester]

Time to get on with mine, the panel is at the post office. I reckon I will just go with the MOS module too. I was thinking of buying of the prototyping board shields and soldering a MOS on to it but for $8 for the MOS board I couldn't be bothered.

The only thing I don't like for now is that I think RCA type connectors are rubbish. I will probably hash it up using those but order a two pin DTM panel mount connector to replace them later on. The hole is bigger for the DTM so it won't be an issue to change later, I just need to leave a service loop in the wiring to crimp the pins on after removing the RCA connector.
Are you powering it via the 12V in to the UNO board? It looks as though that is available via the V-in socket on the riser?

[peter_4059]

I'm powering the arduino via usb and the mos board by the blue terminal blocks because my power supply for the light box is 13.6v and I wasn't sure if the arduino would like more than 12v.

[The_bluester]

I had a dig for the spec sheet and it says 7-14V so it should be OK with my normal power supply. At least if it is not a board is pretty cheap. I am hoping to keep all my power supply arrangements unified so I hope it is happy with it.

[peter_4059]

I guess you just need to ensure you aren't trying to put too many amps through the Arduino since the traces on the PCB will have to transmit the power from the 12V input plug to the VIN pin. That is essentially what others are doing with the cloudy nights approach so it should be ok.

The advantage of going straight to the VIN on the MOS board is that part is rated for 24V 5A. I suspect the GND part of the 12V MOS circuit will be common with the GND pin that connects to the Arduino in any case.

[peter_4059]

Just found this on the official Arduino site under Documentation:

"The Arduino Uno board can be powered via the USB connection or with an external power supply. The power source is selected automatically. External (non-USB) power can come either from an AC-to-DC adapter (wall-wart) or battery. The adapter can be connected by plugging a 2.1mm center-positive plug into the board's power jack. Leads from a battery can be inserted in the GND and Vin pin headers of the POWER connector. The board can operate on an external supply from 6 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may become unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts."

[The_bluester]

I might wire the power separately then just in case. I will be running an A2 panel with this (Went as big as I thought I would ever need) so it might be best to keep the panel current off the uno.

[Astroman]

The Arduino will be getting its power from the USB port that will be controlling it, wouldn't it? Then all that is needed if using the MOS board would be to run the ground, Signal wires from the Arduino to the MOS board then the LED panel and 12v supply from the terminals. Is the 5v rail needed into the VCC of the MOS board? (not sure what this does) I guess so to turn the MOSFET on and off via the PWM? So the Arduino will only be drawing little current to pulse the signal. I doubt enough to damage anything on the MOS board, Arduino or the computer.

[peter_4059]

I think Paul was planning to supply 12V via the jack on the Arduino and wire the Arduino GND and VIN to the MOS board GND and VIN rather than supply 12V direct to the MOS board. I think either will work and in both cases I he will need the 5V, GND and SIG connections between the two devices.

[The_bluester]

For the moment I powered it via the DC in of the Uno and it is working fine. I need a sheet of ND filter though, with the ASI294 and it's liking for 4 second + flats it runs the panel down to about level 3 even with a teatowel over the dewshield.

[peter_4059]

Can you give it a 9V supply? I use these:

https://www.jaycar.com.au/multi-voltage-regulated-adaptor-module-1-5a/p/AA0372

[The_bluester]

I might just go and buy a 9V plugpack and see how it goes. It will increase the current slightly to get the same brightness but it will still be at such a low level I doubt the Uno circuit track will be at any risk.

If it all works out I will package it all up in an enclosure with a 12V/9V DC-DC supply to keep the wiring simple.

[The_bluester]

I grabbed a 9V plugpack and gave mine a test run on the weekend, nice to get good quality flats easily. Voyager handled it easily once I loosened up the tolerance on how close to the requested ADU count I wanted so it would work with a fixed exposure time and the available steps in panel brightness (To make it possible to use a standard master dark-flat)

We also used SGP to directly control the panel and do flats for a friends newt.

I should have done it ages ago!

[Astroman]

I cannot wait to try mine with Voyager, once my Observatory has been moved to a dark sky. I'll be putting all the gear together in a week or so. I'll most likely be getting the A3 size Panel as it will probably be all I will need for my gear. I doubt it will change much in the next few years.

[turbo_pascale]

I've just made a video of my build as per the above.

https://youtu.be/2RQyRsJflmY

I've been talking to the author of Astro Photography Tool (APT) who is looking to add this device in to the next beta, so hopefully we can benefit from it (I've not used SGP before)

[torsion]

Haha, that is funny Rob, you did a much better packaging job than I did.

I used my daughters BBC Micro:bit board and programmed it with the latest sketch (with the capital 'O' characters instead of zero's, which had me going crazy), and now it is working great. I selected the appropriate pin on the Micro:bit, and added one of the onboard LED to represent the brightness for some human feedback.

Although I ordered a 12V LED panel (ebay $45), I received a 5V version including a 2A USB charger. I pulled it apart and at full brightness the little control board provides ~3.6V to the LEDs, so then I thought to use the 3.3V of the Micro:bit, powered from the USB connection to the computer. This may not give me the maximum brightness, but I think that is ok.

My internal panel wiring is slightly different than in Rob's video, from the original control PCB it provides power to the LEDs going in two directions, up and down, so hence there are two pair of power lead coming out of my panel.

I also used the XC-4488 from Jaycar. The Vin is connected to a 3.3V test point on the Micro:bit (hence the green wire coming out of nowhere on the board), while the 'SIG, Vcc and GND control inputs' are from the IO pins. There is a 3V pin, which I use as the Vcc control input. I tried to use that pin for the mosfet Vin, however when connected, the panel is not as bright. Not sure why that is.

I tested it in N.I.N.A. and that seems to work ok.

All in all, it is working great and now I will see to run it with my scope.

Attached are a few photos and the sketch for the BBC Micro:bit board and has some comments and links on how to set it all up (it doesn't have the PWM frequency mod).

cheers,
Bram

[turbo_pascale]

I'm trialling SGP at the moment (moving from APT to see how I go), and it's not working properly.
Apparently, according to the authors over at SGP, the "V4 Protocol" doesn't work reliably (ie the sketch I based it off). They recommend going back to the original one, which I may try next.

Anyone else had a try in SGP?

I'm holding back on trying NINA, just waiting for it to settle down a bit more.

I'm going to take a look at Voyager too.

[peter_4059]

Rob,

I'm using it with SGP. Works fine for me. My sketch code is in a text file in this thread:

http://www.iceinspace.com.au/forum/showpost.php?p=1457599&postcount=33

Peter

[turbo_pascale]

Hi Peter,

Yep, that looks close to the original one with the frequency tweak.
It's kind of working, but SGP binds up waiting for it to respond.
At least it's not completely choking on it anymore.

Thanks for the pointer!

[peter_4059]

Just a quick follow up on this thread for people considering NINA. There was actually an error in the original code by Jared in the early links in this thread. They relate to use of 0 instead of O in some of the responses and also use of serial.println which returns a carriage return as well as a line feed when the original code only wanted a line feed. For some reason SGP didn't care about these however NINA wasn't as forgiving. I've now managed to fix my Arduino sketch to address both of these and NINA is happy!

These are discussed and corrected in this link:

https://github.com/ivonnyssen/ArduinoFlatBox