Elenco Electronic Playground 50-in-1 Experiments - Manual (Page 61)

-61-
This circuit is similar to the last one. Connect the wires
according to the Wiring Checklist (noting that the
transistor bases are not connected although their wires
cross in the schematic). Press the switch and hold it
down. The LED lights and you hear sound from the
speaker. Turn the knob on the variable resistor and the
frequency of the sound changes. Can you tell what the
LED is really doing? It is actually blinking about 500
times a second, but to your eyes it appears as a blur or
just dim. (This is why we told you not to replace the large
capacitors with small ones like these in the last
experiment). You can experiment with changing component values if
you like. The 470
Ω resistor limits the sound loudness,
replace it with a wire to make the sound louder and
replace it with a 10K
Ω to make the sound softer.
Swapping the two capacitors in the circuit will make the
sound frequency higher, replacing them with the 10
μF or
100 μF will make the frequency much lower. You can also
change some of the other resistors.
EXPERIMENT #42: Noisy Blinker
Wiring Checklist:
o 27-to-56
o 55-to-52-to-43-to-41-to-39
o 40-to-1
o 2-to-16-to-30
o 18-to-31-to-51
o 38-to-23
o 25-to-19-to-32
o 15-to-33-to-49
o 48-to-42
o 17-to-20-to-26
o 5-to-21
o 6-to-22
Schematic