docs: update voltmeter drawing and added geogebra

README.md

@@ -4,6 +4,33 @@
 
 ![Liz Sensor Voltmeter](</assets/svg/Liz Sensor Voltmeter.svg>)
 
+
+### Voltage Divider Calculation for Wemos D1 Mini
+
+To measure a higher voltage than 3.3V using the Wemos D1 Mini's ADC port, you can create a voltage divider with 47kΩ and 4.7kΩ resistors.
+
+#### Voltage Divider Formula
+
+$`V_{out} = V_{in} \times \frac{R2}{(R1 + R2)}`$
+
+#### Given Values
+
+- $`R1 = 47kΩ`$ (47000Ω)
+- $`R2 = 4.7kΩ`$ (4700Ω)
+- $`V_{out} = 3.3V`$ (ADC input maximum)
+
+#### Calculate Maximum
+
+$`V_{in} = \frac{V_{out} \times (R1 + R2)}{R2}`$
+
+Plugging in the values:
+
+$`V_{in} = \frac{3.3V \times (47000Ω + 4700Ω)}{4700Ω}`$
+
+$`V_{in} = 3.3V \times \frac{51700Ω}{4700Ω}`$
+
+$`V_{in} \approx 36.3V`$
+
 ## Liz Sensor BME280
 
 ![Liz Sensor Voltmeter](</assets/svg/Liz Sensor BME280.svg>)