beautypg.com

Project #625, Led flasher, Project #626 – Elenco Upgrade Kit SC100 to SC750 User Manual

Page 197: Led flasher with sound, Led flasher with sound (ii) project #627

background image

-56-

Project #625

OBJECTIVE: To construct an LED flasher.

LED Flasher

Set the adjustable resistor (RV) to the top position and then turn on the
slide switch (S1). The LED’s (D1 & D2) flash at a rate of once per
second. As you adjust RV’s knob down, the LED’s flash faster. When
RV is at the bottom, the LED’s turn off.

Project #626

OBJECTIVE: To construct an LED flasher with sound.

LED Flasher with Sound

You can modify project #625 by adding a transformer (T1) to drive a speaker
(SP). Set the adjustable resistor (RV) to the top position and turn on the slide
switch (S1). The speaker sounds as the LED (D2) flashes several times per
second. Increase the rate by moving RV’s knob down.

OBJECTIVE: To construct an LED flasher with sound.

LED Flasher with Sound (II)

Project #627

Modify the frequency by replacing the 0.1

μF capacitor (C2) with the 10μF

capacitor (C3, “+” side on the right).