(Day 3) Creating a Night Light and the Hot Dog Circuit

For our Day 3 warm up we were given a hot dog circuit. Some of the LEDs ran in series with the hot dog, while the others ran in parallel. It turns out that the LEDs in series were the ones that lit once current flowed through the hot dog, which slowly cooked until it burned and started smoking (as you may see in the picture below). Like college students, current flows down the path of least resistance, which are the LEDs in series.

Dusk to Dawn Light Lab:

In this lab, we essentially created a night light. Using a photocell, a BJT transistor, and an LED we created the circuit pictured below. 

The photocell we used changes its resistance depending on how much light it is receiving. With high amounts of light, the resistance of the photocell is very low and allows current to pass through, drawing the concentration away from the rest of the circuit. At low levels of light, the resistance is high forcing the current to flow towards the BJT and the LED, allowing it to light up.

The BJT (Bipolar Junction Transistor) was very useful in stepping down the current to the necessary value required for the LED to light up. 

Here the circuit is complete, but there is not enough resistance from the photocell for the LED to be able to light up. As I lower my sleeve over the photocell, the changes will take effect.

Below is a successful capture of the "night light" working. Enough light was blocked by my sweatshirt sleeve to simulate low ambient light conditions and power the LED.