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BAT SIMULATOR

BAT SIMULATOR. J. L. Errington. BAT SIMULATOR. To mimic a bat sound we need to have an ultrasonic output sound. This circuit gives a signal with a frequency of 45 KHz or 90 KHz repeating at a frequency of 8 Hz.

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BAT SIMULATOR

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  1. BAT SIMULATOR J. L. Errington

  2. BAT SIMULATOR To mimic a bat sound we need to have an ultrasonic output sound. This circuit gives a signal with a frequency of 45 KHz or 90 KHz repeating at a frequency of 8 Hz. The bat simulator used two NE555 timers. The component used for the practical circuit is a dual NE 555 – called an NE 556. The first stage runs at 8Hz and controls the second stage that operates at 45kHz or 90 kHz The sound is produced by an ultrasonic piezo- transmitter

  3. Circuit diagram for bat simulator 9V 9V 1 14 2.2mF 1nF 2 NE556 13 3 12 4 11 39K Piezo sounder 5 10 16K 16K 6 9 7 8 45 or 90KHz 8 Hz F = 1.44 / 2 R C Here R = 16 K or 8K, C = 1nF Hence F = 45KHz or 90KHz F = 1.44 / 2 R C Here R = 39K, C = 2.2mF Hence F = 8Hz

  4. Circuit operation • The high frequency part (LHS of the diagram, pins 1 – 7) is controlled by the 1nF capacitor and 16K resistors. • The low frequency part (RHS pins 8 – 14) controls the “burst rate”. • The piezo sounder is driven very hard with a square wave and produces harmonics at 2, 3, 4 .. times the chosen frequency.

  5. Tested and working • The circuit is built on veroboard and in a metal box to prevent electrical interference. • A 10k resistor and LED have been added across the circuit to show when its switched on, and a switch in series with the battery to turn power on and off.

  6. FURTHER DEVELOPMENT The 1nF Cap could be increased to 4.7nF A 47K pot +4.7k series resistor would allow signals from about 8kHz to 80kHz (and harmonics to 160kHz) to be generated. A piezo tweeter would need to be used instead of the ultrasonic sender as they are not suitable for work below their fundamental frequency (45kHz.)

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