1. The Automatic Weather Station (AWS)
Electronics basics
Doc Ref no: RTC-AWS _Electronics basicss Date: 28/02/2018

2. AWS POWER SOURCES Battery
A 12Vdc lead crystal battery is the primary power supply for solar powered units. This provides power to the logger.
Mains
Mains – 220Vac plug is a secondary power and charges the battery.
Solar panel
Solar panel – This 18Vdc panel is the secondary power and charges the battery.
This solar panel charges the battery during the daytime and the battery supplies the power at night
As a rule of thumb, solar output is at its optimum for only 5 hours each day. As such, mounting angle and position are vital
5Vdc – is provided by the logger to sensors requiring 5Vdc

3. A electronic circuit is a structure that directs and controls electric currents – the path for a current to flow
Circuits can be:
Closed (complete)
Open (broken)
Short (corrupted)
Primary components of electricity are:
Voltage
Current
Resistance
Current refers to the flow of electric charge
alternating current (AC), or direct current (DC).

4. Michael Mengistu

5. In AC, the direction electricity flows throughout the circuit is constantly reversing (it is alternating direction).
The rate of reversal is measured in Hertz (which is the number of reversals per second)
the South African electricity supply is 220/240 volts AC 50 Hz
In DC, electricity flows in one direction; between power and ground. In this arrangement there is always a positive source of voltage and ground (0V) source of voltage.

6. Water flowing through the hose = current
Water flowing through a hose is a good analogy for visualizing electricity:
Water flowing through the hose = current
The rate at which electrons flow in a wire
Pressure is the force pushing the water through the hose = voltage
Voltage is the force pushing electrons through a wire
Friction between the walls and the flowing water = resistance
Resistance slows the flow of electrons through a wire

7. build-electronic-circuits.com

9. Electronic components
Resistors add resistance to the circuit and reduce the flow of electrical current. Resistance is measured in units of Ohms, or Ω.
Potentiometers are variable resistors - they have some sort of knob or slider that you turn or push to change resistance applied to the circuit.
A battery is a container which converts chemical energy into electricity – it is (simply) said that it "stores power."
A capacitor is a component that stores electricity and then discharges it into the circuit when there is a drop in electricity. Capacitors are measured in Farads.

10. Electronic components
Diodes are components which are polarized and they only allow electrical current to pass through them in one direction. These can be placed in a circuit to prevent electricity from flowing in the wrong direction.
The ring found on one end of the diode indicates the side of the diode which connects to ground. This is the cathode. It then follows that the other side connects to power. This side is the anode.
LED stands for light emitting diode. It is basically a special type of diode that lights up when electricity passes through it.

11. REFERENCES: You may consult the following sources for additional information