This is a donkey sound effect project that easy to builds because use simple components include three IC-555 and LM386 and more little parts. Although at present we use Micro controller IC because small. But some times it is hard to find, so this circuit is suitable for everyone.
When press switch S1 to apply power to this project. The operation of IC1 will be 2 ranges.
– First the high voltage is shown at pin 3 until full time (about 2 second), Then switch to the low voltage automatically. This times is controlled by R1,R2 and C1, C2
This high and low voltage from pin 3 of IC1. We will take it to controlled IC2 and IC3 again, by through diode D1 and VR1 to pin 5 of both IC. Which D1 act as protect external voltage backward to IC1
While IC2 and IC3 are connected to others parts that controlled it generate the high and low frequency as voltage from pin 5.
If high voltage IC will generate high frequency and if low voltage the frequency is low.
Both IC2 and IC3 same work. Because we want realistic sound, Create a two frequency range with a frequency similar to simultaneously make it sound like a chorus.
The IC4 acts amplifier IC2 and IC3 frequency of the speaker, the VR3 as a control signal voltage level before expanding.
The parts you will need.
Resistors 0.25W 5%
R5___________ 270 ohms
R8___________ 27 ohms
SP1- 8 ohms speaker
PCB and more
How to builds
First you need to make a PCB as Figure 2 then assemble all parts on it as Figure 3 , next connect more wire and speaker. Next check for error. Then apply power to the circuit.
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