Tricorder Sound Circuit

Star Trek fans have likely heard the whirling whistle of the Tricorder. After talking with my son Paul about the challenge of designing a circuit to reproduce the sound, I came up with this implementation using three 555 timer chips.

The circuit has three astable multivibrator circuits (oscillators). Two of them have a high enough frequency to create tones, and the other is used to give the wobble sound.

The transistor and capacitor work together with the tone oscillator to make a voltage to frequency converter, allowing the lower frequency pulse generator to raise and lower the frequency of the second tone oscillator circuit. The remaining tone oscillator creates an additional high-pitched background tone heard in the original Tricorders.



Here's the circuit:












Here's the parts list:

R1 - 100k
R2 - 1k
R3 - 10k
R4 - 1k
R5 - 1k
R6 - 56k
R7 - 82 (modify for proper volume with your speaker)
R8 - 56k
R9 - 47k
R10 - 1k
R11 - 100 (modify to proper volume with your speaker)

C1 - 0.01 mf
C2 - 6.8 mf
C3 - 4.7 mf
C4 - 0.01 mf
C5 - 1.0 mf
C6 - 220 mf (power filter capacitor)

D1 - N4148

S1 - SPDT
S2 - SPDT or SPST

BAT1 - 3.7V Li-ion (tone will change with higher voltages - this circuit performed best at this voltage for me)

SPK1 - small 8 ohm speaker

Q1 - 2N3904 NPN bipolar transistor

IC1, IC2, IC3 - NE555 (could be modified to use NE556 dual-timer or NE558 quad-timer)

If you build this circuit - please let me know, I would love to know if it worked correctly for you too! :)