Can you build a switch with one paper clip?
Open and close your own circuits. Take control!
Send coded messages with sound. Decode secret messages.
the matching image on the next slide.
to open and close a circuit loop.
in the switch card.
and two beeps for NO.
before there were telephones.
(short short short) (long long long) (short short short)
O _ _ _
S . . .
in Morse code.
letter by letter.