This is just a simple implementation of the MCP3208/MCP3008 A/D chip on a Zero footprint.
I added 2 Form "C" 125vac/2amp 250watt relays to make it more useful.
Relays terminated on 3.5mm screw terminals, A/D inputs on 3-pin .1" pin headers.
Analog signal (3v3 max)
On-board power supply accepts 2.5mm standard Barrel plug, +7.5V < +24V,
Later version includes optional 8-resistor 2k2Ω SIP pullup- for supervisory loop sensors.
Step 1: Get Your Parts Together!
Download a Digi-Key parts list by clicking HERE
Download the CAD file by clicking HERE
Click HERE for an eBay link $2 Esp12-e
Step 2: Clean Your Parts, Insert Parts, Trim Leads, Resin, Solder...and CLEAN!
I chose to make Analog inputs 0-3
into 2k2 pull-up INPUTS,
-for "supervised" alarm inputs, -using 2k2 5-pin SIP resistor network
I included a TMP36 on Analog 7 for on-board temperature input,
Analog 4,5,6 are 3-wire GENERIC sensor inputs (0 to +3 volts).
Step 3: Program It!
Python / MQTT client?