Physical Computing – Lab 1

September 11, 2007

1st Circuit

J’s Journal- notes and observations

1. In the beginning, the 7805 5V regulator was getting really hot and I wasn’t getting a voltage reading in another part of the circuit. There must have been a short circuit but somehow I fixed it unintentionally. I think the 2 power poles were touching the plastic body of the voltage regulator. Small burns on voltage regulator. The AC adapter is putting out 17V even though its supposed to only put out 12V. That is probably the issue. The Voltage adapter can’t handle bringing down 17V to 5V.

2. Various Voltage Readings – I got 2.47 across the 220 ohm resistor when the switch was flipped and the LED was on. 2.18 across the LED.

3. Short- was not able to get any short by touching the 2 poles of the switch, got sparks from the 2 poles of the power wires.

4. Plugged Yellow and Green LED in series. I get 2.7V across Green and 2.2 across Yellow. Added a Yellow and got 1.9V from all 4.

5. Plugged in 3 Green in Series, I get a 2V reading across each and a 2.7V across the 220 ohm resistor

6. MEASURING AMPs – 2 LEDs parallel – measured Amps between 2nd LED and Switch 12.95mA. 13.03 mA between resistor and switch. 198 Amps between switch and ground


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