Page 53 - The Basics IA by ETron Circuit Labs

higher the frequency will be of the tone emitted from the speaker. Transistor Q1 amplifies the strength of these pulses and sends them to the speaker.Procedure:Assemble the circuit and connect a 9-volt battery to the Battery Snap and you will hear an approximate 500Hz (55 cycles-per-second) tone from the speaker. If you put this circuit in a small box that can close out all the light, the speaker will be quiet. But as you try to open the box, the speaker will let out a high-pitched squeal, so we call it a screaming box. Try it in the refrigerator to catch late-night snackers. Have fun!Note: You may still hear a small buzz sound even when you have the photocell completely covered with your finger.Check Your Work HereR3R1Here’s What You’ll Need...RESISTORhole 8ahole 9b100 Ohm - (Brown, Black, Brown,Gold)R2hole 8ihole 19hhole 20b220 Ohm - (Red, Red, Brown, Gold)PHOTOCELLP1C1B1 Q1ehole 19a hole 20ahole 20h hole 2hDISC CAPACITORS 104 0.1uF 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 REDBLACKred = hole 30e black = hole 30hc bNPN 2N3904Collector hole 9gBase hole 8gNPN TRANSISTORINTEGRATED CIRCUITEmitter hole 7gSPEAKERWIRESIC 1SCAN HERE TO SEE MORE ONLINE2.2K % (Red, Red, Red, Gold) 8 7 6 5 holes21e-18ehole 21b1234holes 21f - 18f SPKR 1hole 8bhole 9hW1 = 21c & 30b W2 = 9c & 30c W3 = 7j & 30jW4 = 21j & 30i W5 = 21d & 18g W6 = 19d & 20g51LAB 26Visit us online at www.ETronCircuit.com for more exciting projectsLab Observations