Page 37 - The Basics IA by ETron Circuit Labs

The LED across the output lets you know that there is voltage. The resistance across transistor Q1 is varied with the potentiometer. When the resistance across Q1 is high, there is no voltage at the output. As you lower the resistance across Q1 with the potentiometer, the voltage increases at the output of the power supply. This is a DC to DC power supply.Procedure:Assemble the circuit and connect a 9-volt battery to the Battery Snap and you should see the LED light up. By using a multimeter at the output, you should be able to adjust it from 0 to 9 volts.This is an excellent project to power projects that require from 0 to something less than 9 volts.Check Your Work Here a b c d e 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 a b c d e f g h i j 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 f g h i j Here’s What You’ll Need...R2 hole 2dhole 14dNPN 2N3904Collector hole 16cBase hole 15cR1Q1eRESISTOR220 Ohm - (Red, Red, Brown, Gold)hole 14ghole 14e6.8K & (Blue, Gray, Red, Gold) c bNPN TRANSISTOREmitter hole 14cPOTENTIOMETER R3hole 25a hole 15dhole 30gAnode CathodeLIGHT EMITTING DIODE (LED)LED 1Cathode (flat side)B1hole 2e hole 2fREDWIRESW1 = 16a & 25c W2 = 14i & 30i W3 = 2j & 14j Output (+) = 14a Output (-) = 14hBLACKred = hole 25e black = hole 30jSCAN HERE TO SEE MORE ONLINE35LAB 18AnodeVisit us online at www.ETronCircuit.com for more exciting projectsLab Observations