Page 31 - The Basics IA by ETron Circuit Labs

Here’s What You’ll Need...RESISTORR3R1 R2hole 11jhole 12b hole 13b6.8K & (Blue, Gray, Red, Gold) hole 11cC110uF hole 12hINTEGRATED CIRCUITELECTROLYTIC CAPACITORShole 13h8 7 6 5 holes13e-10eLO, and how long it remains with one of the two states on its output depends on external components, i.e. resistors and capacitors connected to the pins of the 555 Timer IC. The square-wave pulses emitted by Pin 3 are called “clock pulses,” Digital circuits need these kind of clock pulses.This circuit was designed to make the outputs change from one state to another about 4 times a second, 4 pulses per second. You can experiment with changing values of R1, R2, and C1 and see the LED blink at different rates.Procedure:Assemble the circuit and connect a 9-volt battery to the Battery Snap. The LED should blink on and off at a frequency of about one time per second.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 IC 1hole 24j220 Ohm - (Red, Red, Brown, Gold)16K % (Brown, Blue, Orange, Gold) LED 1Cathode (flat side)hole 24e hole 24f1234holes 13f - 10fhole 12cAnode CathodeLIGHT EMITTING DIODE (LED)REDBLACKB1red = hole 30e black = hole 30hWIRESW1 = 24d & 30dW2 = 13c & 30bW3 = 13i & 30i W4 = 11d & 12g W5 = 13d & 10gSCAN HERE TO SEE MORE ONLINE29LAB 15AnodeVisit us online at www.ETronCircuit.com for more exciting projectsLab ObservationsFormulas for the 555Period = (0.693)(R1+R2+R2)(C1) seconds Time HI = 0.693 (R1+R2)(C1) seconds Time LO = 0.693(R2)C1) secondsFrequency = 1.44 Hz (R1 + R2 + R3)(C1)Percent Time HI Duty-Cycle =(Time HI + Time LO) x 100%Value LimitsMax or R1 + R2 = 3.3M OhmsMin of R1 + R2 = 1K OhmsMinimum recommended Capacitance of 500pF