The second meeting

figure.1 simulation of charge up circuit

figure.2 output of the current

As were shown in the pictures above, a DC power source of 16 volts is assembled in the LHS and a capacitor of 100uF is in parallel with a resistor of 1ohm. In this case, the resistor is on behalf of the magnets which we had mentioned. Once the capacitor is charging to 16 volts, it is essential of obtaining the current once the switch on the RHS is on. With respect to figure.2, it is presented the current is starting to decline after 3ms and it is due to the transient phenomena regarding the capacitor & resistor circuit.

figure.3 simulation of the photo diode

figure.4 output voltage of amplifier

As can be seen in the figure.3, two standard photo diodes are connected to a bipolar transistor individually. Specifically, the common-emitter transistor is treated as an amplifier in order to detect the voltage fluctuation concerning the output side. Two capacitors which located at the base part as well as the output side were aiming to filter the DC voltage source. As a result, the input AC signal should be amplified and detected at the output side of the transistor.

First Group Discussion ( the parameters)

As has been mentioned before,the basic principle of this project is energy transformation.




The C in the LHS is the capacitance in the circuit and the V is the voltage across the capacitor. In regard to the RHS, the m stands for the mass of the bullet while v is the velocity. Initially, we assume the velocity of the bullet as 1m/s. Furthermore, the safe voltage is defined as 16 volts and the mass of the bullet is assumed to be 12 grams approximately.Therefore,the value of the capacitance can be obtained according to the equation.


Nonetheless, the capacitor with 100uF capacitance is finally applied because of the safety consideration. With respect to the charge up component, an AC power supply is connected to the capacitor in series. Assume the resistance in regard to the load is 1 ohm, and the current across the rail is 16A.

Basic principles of miniature launcher

The basic principle of miniature launcher is energy transformation which intend to transform electrical energy to kinetic energy.

As has presented in the picture above, our supervisor explained the principles and specific parameters during the first meeting. Firstly, a capacitor or several capacitors are employed for supplying current and DC resources are using to charge up the capacitors.The following part is the magnet together with the rails which used to send bullet.Once the current pass through the rails, the bullet will start to move as a result of Lorentz force.After that, two photo diodes as well as LED are installed for measuring the actual velocity of the bullet.Specifically, a amplifier circuit is linked to the photo diode and once the bullet detect the lights from LED, it is expected to obtain a distortion of pulse in the output side of the amplifier.In that case, the distance divided by the time between the two expected distortion of pulse is, theoretically, the actual velocity of the bullet.In general, the entire circuit should be assembled in a box and three switches are necessary to be applied.