Most of the price was actually assembling the PCB, and looking around the internet, I discovered the wonderful invention of the hotplate, and that I could make all of my PCBs myself for more than half the cost. Now, while I could have bought one on eBay, I decided to take up the challenge of making my own (because why not) and to make it as functionally portable as possible, so Ember was born.

I started reading how hotplates work and looked around the internet to see if anyone had made one, and I stumbled upon this repository (https://github.com/ikajdan/reflow-hot-plate). It was basically what I wanted to make, but reading through, I found that although it went up to 210 °C, the hotplate size was rather small. Also, it needed an external DC jack along with USB-C to be able to control/monitor it from a laptop.

Features/Specs:

- USB-C Power Delivery up to 100W (20V) using TI's TPS25730D

- STM32WB55CG microcontroller with Bluetooth support

- Large(ish) 120mm x 120mm flexible heatbed for big PCB reflow (JLCFH)

- Dual temperature sensing with MAX6675 thermocouple and PT1000 RTD

- OLED display with rotary encoder for easy control and preset management

- NFC support (because why not lol)

- Gate driver for precise PWM heatbed control

- Current and board temperature monitoring for safety

- 32MB Flash memory for graphics and data storage

- Portable design with custom acrylic / nylon case

If you want to see the complete journal of how I made it and all of the design decisions I made, you can check it out here: https://blueprint.hackclub.com/projects/1701

Here’s the GitHub repo for anyone interested in making their own: https://github.com/notaroomba/ember

Thanks to Hack Club’s Blueprint for sponsoring this project!