Flashing LED Used as an Electric Pulse Generator. Flashing LED Used as an Electric Pulse Generator Flashing LED is an optoelectronic device with an integrated circuit including pulse generator, electronic switch and crystal of the light emitting diode. Generator chip is located at the bottom of anode connection of a diode, crystal is located on the cathode connection. Both parts of the device are connected with thin bonding strips. Generator chip includes high frequency driving generator and high frequency divider. The device includes also electronic switch and protective diode. It is required to avoid polarity reversal of the device. Flashing LEDs designed for 9V power supplies have limiting resistor. Flashing LEDs are used with low voltage power supplies without any limiting resistor. Pulse generator with flashing LED operates as the following: Cost effective pulse-burst generator has only Schmitt trigger. When LED flashes, voltage level is equal to logical zero at the input of 1 integrated circuit. The voltage level between flashes is equal to logical one and RC-generator of R2 and C1 elements and the integrated circuit switches on. Pulse burst are registered at the output. The LED flashes with the same frequency. If you switch acoustic source to the output you may hear the signal. If R1 resistor rating increases up to 150 kOm, recurrence interval of pulse burst will be increased up to 600m/s, and frequency will be decreased up to 1.5kHz. Smooth variation of sound frequency may be achieved by interchanging positions of R1 resistor and LED in the circuit, and changing R1 resistor rating.
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