Project:
Nikon D800 for astrophotography ?

Contents:

1. Nikon D800 overview
2. Adapter Nikon to Pentax 645
3. Lid, Dove tail, Tube ring
4. Focuser mechanism, driver
5. Off-axis guide camera
6. Main bracket
7. Wiring & USB-HUB
8. Test with Windows and APT
9. First Light
10. Balance system
11. Nikon vs Canon, Pentax FA vs Pentax
12. Tilt adjuster
13. KStars/INDI setup for Nikon
14. Correction of tilt
15. To be continued

Note:
I take no responsibility or liability for what are written here, you use the information on your own risk!

Related projects:

• KStars / Setup GPS Raspberry
• KStars / Setup WIFI Hotspot Raspberry
• KStars / Linux commands and udev rules
• KStars / Raspberry Power
• Setup astroserver with Raspberry Pi3
• Setup astroserver with Raspberry Pi4
• Setup astroserver with Raspberry Pi5

1: Raspberry Pi5 DC/DC converter

The Raspberry Pi5 computer needs 5 Volt and 5 Ampere, 3.5 Ampere for the computer and 1.5 Ampere for the peripherals. It need a power supply that can deliver that power. I used a similar DC/DC converter to an earlier project. This one will be built in the same enclosure as the Raspberry and direct connect to the 40 pin terminal, not the USB-C port. The USB-C cable protrude far away from the chassi and the risk of damage is high.

After that I built this it has come a Hat that you can connect directly to the Raspberry, it has built in DC/DC converter. Use that one instead, much easier.

Raspberry Pi5:

The Raspberry Pi5 looks almost the same as the older Pi4, but the cooler is different. I use the 4GB version which I think will be enough, much cheaper and only this was available.

Enclosure:

The Raspberry Pi5 will be placed on the upper part. The hooks grab the cooler's chassi. In the lower part will the DC/DC converter be placed. 8 to 24 Volt input and 5 Volt at maximum 5 Ampere output.

This is how it looks like when 3D-printed.

The hooks grab the cooler on the back side.

Later a lid will push the Raspberry in place and lock it. Now I can direct connect the power to the 40 pin terminal. No longer a protruding USB-C cable on the side. A screw terminal for the incoming power, later another one for 5 volt output to some extra device.

With the lid mounted it lock the Raspberry in place. The lid also protect the power cables that goes between the Raspberry's 40 pin terminal and the DC converter.

USB C power connector:

Normally the Raspberry Pi5 get the power from the USB C port. Not good, this cable can be broken when it protrude as it does here.

Using the 40 pin connector:

I plan to use the 40 pin connector as a power inlet to the Raspberry Pi5. I use the 2 positive 5 volt (red) and the 5 gnd (black) on one of the rows, 20 pins. I have cut some of the pins to not have any short cut between them. You can't let high current through these tiny connectors, but I will have an external 5 volt power supply to the USB Hub. Then I limit the current to 3.5 Ampere.

I follow this schematic when I connect the cables:

• 40 pin pinouthttps:// vilros.com/ pages/ raspberry-pi-5-pinout

My 20 pin connector connected to the lower half of the Raspberry's 40 pin connector. Be very carefully to solder the cables to correct pin and mount it correct on the 40 pin connector. When connecting directly to this 40 pin connector you over ride some of the safety, you must have a current limit or fuse in your power supply. The one I use have a 5 Ampere limit.

Lid:

The lid has a slit for the cables.

No protruding cable:

Now it's less risk to broke the power supply cable. You can read here how to setup the current handling of the Raspberry Pi5: Setup WIFI Hotspot.

Configure Max Current:

My power supply is a standard 12 to 5 volt DC/DC 5 Ampere converter. There is no intelligence built into it. Then the Raspberry assume that it only can deliver about 2 ampere and limit the peripherals current consumption. There is a workaround for this: How to power the Pi 5 without the official power supply . You only do this if you have power problems.

The file "config.txt" they talk about is stored in the firmware map. Later I found that it's possible to do this from the Raspberry desktop. Use the Raspberry Pi configuration from menu. Setup > performance. At full current, turn on.

With the sudo nano command I edit the config.txt file:

• sudo nano /boot/firmware/config.txt

Scroll down to the end and paste the two lines at the end:

• psu_max_current=5000
• usb_max_current=1

Quit with Ctrl X and type Y (Yes) and then Enter to save the file.

Note: I'm not sure about the line "psu_max_current=5000", some says I should place it here and some that I should place it in the eeprom.

Do a check that the new line is in the file at the end. If it's okay reboot the Raspberry. The first test I did with the WIFI spot showed a big improvement. Much faster response and no time out yet. Still it can be improved, but I can use it now. I know this problem with Raspberry and power supply from earlier but forgot it because all other things looks to work so fine. Thanks to all my friends that has come with ideas what I should look after.