Summer is almost over, so I found some time to write down the first article.
Some time ago I started thinking about making good quality, from both technical and aesthetic point of view, flatfield panel which can be used in the field powered by 12V battery. Two obvious possibilities are to either buy a cheap LED panel lamp in a home-improvement store or buy a dedicated flatfield panel (like Aurora which I heard is great).
I haven't gone with these two approaches because in my case I need min. 200mm diameter panel, so in the first approach, you usually get something big and bulky, in the second you spend quite a huge amount of money. Also, many DIY panels are glued, taped, etc so these are far away from my aesthetic expectations.
After thinking, reading and checking I went for the following setup:
electroluminescent circle panel (25cm diameter),
laser cut opaline plexiglass,
a couple of screws, especially nice nickel binding screws.
BOM (shipping included):
EL panel (including inventer) from aliexpress: $36.50
plexiglass (including cutting) from the local market: $16.50
5 binding screws (mainly cost of shipping): $4.00
EL panel is actually blinking with high frequency, you need to get it dim to make sure exposition time is enough to smooth it out, I went with opaline plexiglass with 20%-30% of transparency, it seems to work well. When it is lit up IMHO it doesn't need to be super evenly illuminated as the focus of your telescope is anyway set up to stars/infinity which will blur up the image of the panel. Also from a spectrum perspective, it needs to give you enough light on each channel, but if you calibrate each channel separately not necessarily equal ADU per channel.
Here is the project for plexiglass (CC) (click for a larger view):
I decided to cut a hole in the bottom of the inverter and to mount it directly to the panel, this makes this device one integrated piece of hardware without extra cables or so. Also, the EL panel is a little bit bulky in the place where wires are connected. These are the reasons for the hole in the plexiglass.
All pieces collected together:
Details of the inverter:
To prepare inverter, you need to:
cut the hole,
cut off case feets to make it flat on the surface of plexiglas, and
solder new wires to the bottom (I also used antistatic foil to isolate PCB and changed the connector to XT30).
Bottom of the prepared inverter:
After it is all put together, the connector and the bulky part of EL panel fully fit in the hole, so the whole thing is flat.
Removing foils, screwing it together with binding screws (which I had to shorten a little bit) and the final product looks like the following:
Here are the first flat frames taken by this panel. These are integrations of 20 subs per channel for LRGB.
(TODO - attach image)
Feel free to leave me a comment if you like it (or not).