Killer Power Electronic Circuit

=Problem Definition= We first found a circuit that uses two identical photoresistors and two identical relays to detect the direction of movement of objects. After we are familiar with and understand its specific working principle, we start to determine the power supply voltage and components in the circuit through calculations Resistance range and selection of component specifications. 1.Design sneaky ways to serve as killer circuit to destroy the main circuit. 2.Simulate the main circuit and the combined circuit. 3.By calculating the power supply voltage of the circuit and the resistance range of the components, we can select the components of the required specifications. 4.Purchase components and build the final product. 5.Circuit debugging and experiment

Special Statement
Due to the the impact of the epidemic, our team had to be divided into two different teams. Two different killer circuit designs and final products were completed in China and the United States respectively.

=Objective= The goal of this project is to install a hardware Trojan horse on the designed circuit produce the finished product.

=Background= The project requires the addition of a Trojan horse to a familiar circuit. Make a circuit to realize self destruction is the premise of the circuit has a very thorough understanding of the permanent self-destruct or transient circuit self-destruct will be applied in many aspects of our life, whether it is necessary measures to protect the safety of property information electronic science and technology company, or entertainment aspects involved, the design of the circuit self-destruct has broad application prospects.

=Choose A Suitable Circuit=

Principle
when the object moves from the photosensitive resistor RG2 to the direction of RG1, the RG2 is firstly blocked by the object, which causes the RG2 resistance value to increase and the bridge balance is destroyed. The bridge output UAV is less than 0.Compound pipe Q1 on, Q2 up.Relay K1 coil has current flow, the relay is often open contact suction.By the same principle, according to the working order of the relays, we can judge the direction of the object's movement.

Design Considerations


1.TCRT5000 module (Build In China) The infrared emitting diode of the TCRT5000 sensor continuously emits infrared rays. When the emitted infrared rays are not reflected back or reflected back but the intensity is not high enough (indicating that the diode is always in the off state), the photosensitive transistor is always in the off state, and the module Output high level; when the detected object appears in the detection range (the indicator diode is lit), the infrared rays are reflected back and the intensity is large enough, the photosensitive transistor is saturated, and the module outputs low level at this time

2.Use optical signal as the switch of bridge drive power supply（Build in United States） The principle of the killer circuit, according to the design requirements, when an abnormal signal appears from the outside (this design assumes that the abnormal information is an optical signal), it can make the bridge circuit and its accompanying control circuit lose its performance and achieve a temporary protection effect. In view of the above design ideas, the trigger design of the overall concealed circuit is to control the drive power of the bridge and the power supply BAT3. When the external abnormal information occurs, that is, when the light sensor (photo-resistor) in the concealed protection circuit receives the abnormal light source, the sensor is turned on, the base voltage of the NPN transistor is greater than 0.7V. At this time, the transistor is turned on, the overall killer circuit is turned on, the relay RL4 is turned on, and the relay reed is pulled to the coil side, which finally causes the bridge drive power supply to be disconnected, making the main The circuit does not work. In this circuit, the NPN transistor acts as a switch.

Circuit simulation
1.TCRT5000



2.Photo-resistor



Experiment Results
In the circuit, the bridge balance is used as the trigger condition. Before use, the bridge balance must be ensured, because the level change is used as the trigger choice for different circuit work. When Uab>0, the base voltage of the transistor Q7 is greater than 0.7, causing Q7 to conduct Then, the whole circuit connected to Q7 is turned on, the relay RL2 is powered on, and the reed is attracted to the coil side, so that other circuits connected to the relay RL2 start to power on; similarly, when Uab<0, the transistor Q2 The base voltage is greater than 0.7, which causes Q2 to be turned on, which in turn turns on the overall circuit connected to Q2, the relay RL2 is powered on, and the reed is attracted to the coil side, so that other circuits connected to the relay RL1 start to be powered on. Here we can see the test results of the two cases.

=Final Design&Product=

Designed and Built in China


=Feedback and Thinking= Before doing circuit simulation, we calculated the approximate specifications of the components required in the circuit. We found that Bat3 and 5 only require 9V, while other power supplies may require 12V. The final test results are consistent with expectations, and the circuit can run successfully and operate according to the principle.

=Circuit Components Specifications=

=Team Members=

=Additional Documentation= Agenda

Agendas

Meeting mintues

Meeting minutes

Time Management

Timeline

Budget

Budget Table

Video of Presentation

Video

Circuit Simulation Document

Simulation