Week 1 (3rd of February 2017)

During the first project week, the transmitter and receiver circuit designs were discussed and agreed upon by all group members. The initial circuit design chosen for the transmitter is shown in Fig. 2a, while the circuit diagram for the receiver is shown in Fig. 2b.

Fig. 2a) transmitter circuit 

 Fig. 2b) receiver circuit

The circuit was simulated using PSPICE. The two circuits were constructed separately on two separate SK10 boards and tested afterwards.

Transmitter circuit

Two MOSFETs (IRF540) were included in the design, acting as an oscillator by connecting eight cascading capacitors as a “tank” circuit (connecting in parallel with the transmitter coil).

Table 1: Transmitter circuit component list

Component (with value)	Quantity
Resistor (10kΩ)	2
Resistor (94Ω)	2
Resistor (1k)	1
MOSFET – IRF540	2
Inductors (8.6μH)	2
D4148 diode	2
Inductor coil (0.674μH)	1

The following formula was used to calculate the required frequency:

The receiver circuit was then tested using the AC voltage provided from the function generator, with the expected values being retrieved. However, the transmitter circuit was not performing as required, as there was no current supplied to the inductors within the circuit.

This meant that in order to progress further with the project, a simulation needed to be performed in PSPICE to detect why the inductors were not being supplied with the required current. Doing so would also allow any other problems to be identified and dealt with accordingly.  

Receiver circuit

Table 2: Receiver circuit component list

Component (with value)	Quantity
Resistor (1k)	1
Capacitor (6.8nF)	8
LM7805 voltage regulator	1
D4007 diode	4
Inductor coil (1.235μH)	1

The receiver circuit consisted of a receiver coil and a capacitor in parallel, which was used to absorb the electrical energy from the transmitter circuit, while also charging the AC voltage it had received. This was then connected to a full-bridge rectifier, to change the voltage from AC to DC. The low-pass filter (consisting of a capacitor and a resistor) ensured only lower frequencies were allowed to pass through to the LM7805 voltage regulator (which reduced the output voltage from 30V to 5V).