Signal Generator 3.3V-30V PWM Pulse Frequency Duty Cycle Adjustable Module 1Hz to 150Khz LCD Display PWM Signal Generator Module L80 GPS Shield which can measure the capacity

which can measure the capacity of the fully charged battery connected at its inputs it also has 1W resistors that can be used to discharge the battery at the constant current output

a simple quarter-wave monopole antenna or a discone antenna works well

When you need to break a copper track to isolate sections of your circuit

use level-shifting modules to convert signals between 5V and 3

Signal Generator 3.3V-30V PWM Pulse Frequency Duty Cycle Adjustable Module 1Hz to 150Khz LCD Display PWM Signal Generator Module L80 GPS Shield which can measure the capacitySignal Generator 3. 3V 30V PWM Pulse Frequency Duty Cycle Adjustable Module 1Hz to 150Khz LCD Display PWM Signal Generator Module