Miscellaneous DIY Information


Connectors & Cables

Doing things right is hard, especially when it comes to connectors. That is why this summary was created to help out.

Power connectors

Always use the correct thickness wire for the amount of current you expect to pass though. Take a safety margin of at least 25%. Use heat shrink where possible to prevent short circuit connection if something comes loose.

Mini-XLR connectors have a limited current rating, they are not recommended for power or motor connectors.

Motor connectors

RJ45/RJ12 connectors aren't recommended because of their low current rating and inability to handle many mating cycles.

USB connectors

Use USB-A and B as much as possible and use off the shelve cables. This is the most rebust option. USB-C can be used, but it is harder to implement in some applications and aren't as rebust as A and B. USB-C is also hard to plug in when it is dark.

Discord Servers

There are a number of Discord servers where people are happy with anwser DIY related questions.

General Astro-related DIY:

Telescope making:

OpenAstroTech hardware:

General DIY:

Making An ESP32 Microcontroller Board

The ESP32 series of microcontrollers from Espressif have become very popular among hobbyists and in the astronomy sphere. This page goes over the basics of making a custom PCB that uses an ESP32. You can apply the information here to your projects, whether it might be a custom OnStep controller or an electronic autofocuser.

Selecting a chip

Sirawit Moonrinta made a comparison chart on GitHub that can help you select an ESP32, but it boils down to the following:


ESP32 ESP32-S2 ESP32-S3 ESP32-C3 ESP32-C6
Processor 240 MHz single or dual core 240 MHz single core 240 MHz dual core 160 MHz single core 160 MHz single core
WiFi WiFi 4 WiFi 4 WiFi 4 WiFi 4 WiFi 6
Bluetooth BLE 4.2 x BLE 5 BLE 5 BLE 5
USB x
GPIOs 34 43 44 22 22

For a lot of applications you don't need a whole lot and you want to simplify the design, in that case the C3 or C6 might be a good option. If you need the speed or a lot of GPIOs, then an S2 or S3 would be a good option. The original ESP32 is currently the only tested option for OnStep. Issues with USB communication in the OnStep driver cause the ESP32s with built-in USB connectivity to not work correctly. They may work with a USB-to-serial bridge, but that has not been tested yet.

The different packages

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ESP32 can be bought in many different packages. What that means is that they can be bought as a chip or as a module with easy to solder castellated holes. In this case using the chip itself doesn't have many advantages, so we'll only be looking at using the modules.

The following types of modules are available:

Lastly, many of these modules can be bought with either a PCB antenna or a uFL connector. The modules with a uFL connector are usually smaller, but otherwise have the same footprint and pinout as the PCB antenna versions.

The other components we need

The ESP32 doesn't work by itself, we need some extra passive components and chips to make it all work.