Everyday Carry (EDC) Heater

Imagine that you are in a harsh cold island. You only have a USB source, and nothing else to make you survive.

EDCHeater can help you to be warmed up in chill situations!

You can even keep your favorite drinks warm!

Moreover, homeless animals can keep warm in cold climates with a simple power bank, and this piece of life source for hours, and even days!

Let's make all hearts happy!

Technical Details

Front View of Board 1

To prevent short circuits, and to make more lovely design, this board is designed as enclosure. Snowflakes are designed as solder mask clearances. I just illustrated them as like white leds are operated in real application. If you order this board, especially note that this is a two layer board with no copper on top layer. Else you might get a board like on right picture :)

Bottom View of Board 1

White regions show where Z-axis milling process is needed (1.5mm depth) . Board 2 components will fit in those regions. Also you can order without milling and engrave it yourself :)

Be careful that big electronics components need a little bit more space. So it is really hard to make a perfect enclosure by hand, as you can see from right picture :)

Bare copper square pads are necessary to solder and assemble two boards together.

Copper plane is added to store heat.

Front View of Board 2

-Heater ( Below image shows the trace resistance configuration. Approximately 650mA of current will pass through and this equals to 3.25W power consumption. It took many hours to measure every length of the traces one by one and calibrate it. I will try a better approximation for next designs. )

http://circuitcalculator.com/wordpress/2006/01/24/trace-resistance-calculator

-Micro USB connection,

-White LED’s are for lighting and also to prevent power bank's low current sleep mode.

-60C degrees overheat protection circuit. If you use better Op-Amp with higher operating temperatures, you can easily configure it through online NTC Thermistor Resistance Calculators. Below image shows the configuration that I’ve made from:

https://www.electro-tech-online.com/tools/thermistor-resistance-calculator.php

-TSM3404 MOSFET (You can use any alternative generic N Channel MOSFET that has drain current higher than 1 Amps. Be careful with pin configuration!! )

-OpAmp is used as voltage comparator. Main logic relies on this basic circuitry (Heater resistance is added to drain pin of MOSFET in layout).

Bottom View of Board 2

Power rail of white leds and essential components. I tried to make it more stylish :)

Electronics components are kept as simple as possible. So that everyone can make it. If you order these boards, I will help you through comments below as best as I can.

This is my first experience with KiCad. So I'm open to any suggestions :)

Board Specifications

Size:70mm x 70mm

Thickness: 1.6mm

FR4-TG: TG130-140

Track/Spacing: 6/6mil

Hole Size: 0.3mm

Black Solder Mask

White Silkscreen

(You can choose another fashionable colors that you like:) )

Tenting Vias

1 oz Cu

Z-axis milling: 1.5mm depth (Bottom Silk of Board 1 is for Z-axis milling)

Order number on board is not necessary

Extra Notes

-Especially write that board 1 is two layer. Else they might send single layer board with no solder mask on top layer.

-You can also order stencil for better look and easy assembly. If you are not experienced with stencil and wave soldering, PCBWay has discount for automated assembly.

-Board 2 is essential and Board 1 is optional to maket his project. I would prefer Board 2 if you have an experience with wave soldering. Because you can only assemble two boards together with wave soldering tecnique. Never forget to isolate top components with some kind of enclosure for your own safety.

-Finally, everything is open source! Feel free to ask any questions. I will guide you best as I can.