For Arduino enthusiasts and beginning electronics engineers --
This circuit board was originally designed as a motherboard for an RFID controller. It hosts an Arduino Nano and uses a P-channel MOSFET as a "power switch" that you can shut off from your sketch to preserve the lifetime of a 9V or similar battery. (Not a charging circuit -- alkaline/non-rechargeables only!) I have published the design on EasyEDA under an open source license, so if you want to modify or make more of the board yourself, you can!
Using this board requires basic soldering. This is a break-apart package of 4 boards. Size 33.8mm x 75.5mm
The board hosts the following:
- Five "pushbutton" connections (these turn the power on)
- 2, 4, and 8 relay packs available on Amazon
- IR receiver
- Piezo buzzer
- NRF24L01 2.4GHz radio transceiver module
- Solder points for two "Grove" connector terminals (both on A4/A5 aka SDA/SCL)
- Solder points for terminals (such as for RFID reader or other peripherals)
- Solder points to upgrade/replace the built-in MOSFET and Nano's voltage regulator for increased power capacity
Pin assignments:
- Power control: D7 (high=power stays on without button push, low=shut off while no buttons pushed)
- Pushbuttons: A0,A1,A2,A3,A6 (enable via solder pads)
- Relay packs: Α0-Α5,D4-D5, see legend on bottom of board
- IR receiver: D8
- Piezo buzzer: D6
- Battery voltage sense: A7 (0-1023 = 0-15V)
- Radio module: D9 thru D13, with option for IRQ on D3 or D8 if needed (solder pads)