Data Sheet

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238. Geiger Counter

Replace the switch (62) with the reed switch (83) and replace the

speaker (93) with the lamp (76) in project #213. Connect points C

and D with a 4-wire (4), hold the magnet (7) near the reed switch (83)

and you will see the lamp (76) is ashing quickly. A Geiger Counter is

a device for measuring radioactivity by detecting and counting ionizing

particles. This circuit simulates a Geiger counter detecting radioactivity

when the magnet (7) is near the reed switch (83).

239. Proximity-controlled Sign

Replace the switch (62) with the reed switch (83) and replace the

speaker (93) with the lamp (76) in project #213. Connect points G and

H using 4-wires (4), hold the magnet (7) near the reed switch (83) and

you will see the lamp (76) ashing slowly. This circuit could simulate

a person walking by a proximity activated sign. The sign turns on only

when the person is close enough to read it. The speed and message on

the sign could change depending on the time of day.

240. Flashing Alarm Light

Replace the switch (62) with the reed switch (83) and replace the

speaker (93) with the heart LED (69) in project #213. Connect points

C and D with a 4-wire (4), hold the magnet (7) near the reed switch (83)

and you will see the heart LED (69) is ashing quickly. This light could be

in the alarm pane near your front door indicating that you need to close

the door or window before you can set the alarm. Move the magnet (7)

away from the reed switch to simulate closing the door or window and

now the light will go out indicating that you can set the alarm system.

241. A Pacemaker

Replace the switch (62) with the reed switch (83) and replace the

speaker (93) with the heart LED (69) in project #213. Connect points

G and H with a 4-wire (4), hold the magnet (7) near the reed switch (83)

and you will see the heart LED (69) is ashing slowly. Notice how the

light ashes steadily when the magnet (7) is near the reed switch (83).

This could simulate a pacemaker that is keeping a person’s heartbeat

steady.

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