add docs about schematics

README.md

@@ -4,3 +4,24 @@
 platformio run --target upload
 ```
 
+# Single strain half bridge
+
+Single strain consiss of two 1k resistors voltage divider. Fitting two more
+fixed 1k resistors creates a full bridge. 50kg max.
+
+![Single strain half bridge with two additional 1k resistors
+breadboard view](./docs/1-strain_bb.jpg)
+
+![Single strain half bridge with two additional 1k resistors
+schematic](./docs/1-strain_schem.jpg)
+
+# Double strain half bridge
+
+Using two single strain half bridges together forms a full bridge. 100kg max.
+
+![Two single strain half bridges togerher breadboard
+view](./docs/2-strain_bb.jpg)
+
+![Two single strain half bridges togerher breadboard
+schematic](./docs/2-strain_schem.jpg)
+