Here is a Simple Continuity Tester circuit using IC-4011. If you are looking for a simple project for kids to learn oscillator on digital.
This is a tool for check wires or some parts such as coils, the PCBs, speakers, and more. Is it good or bad? in easy to use.
If it is good, you will hear sound on the speaker. On the other hand, NO sound if it is lost.
How it works
In the circuit, it uses the integrated circuit, NAND gate CMOS, CD4011 as the main component.
The IC1a and IC1b are working like an inverter (not) gate. They have a few parts, R1, C1, and VR1 are a square wave oscillator to generate a tone.
Then, this signal comes to the power amplifier (which compose a Complementary pair of transistors) to a coupling capacitor-C1. And to drive a louder tone on loudspeaker that.
The frequency of tone can control with the 10K potentiometer.
How to uses it
We may have 2 ideas to use it.
First, Simple Continuity Tester! When you take a 9V battery to the circuit, do not need to use S1. You use two probes to check many parts. It is suitable for wires and PCBs.
Second, Moss Code Generator! Many Kids may use it for learning moss code in simple.
In addition, we need to connect the input of the other—does not use of IC1—to the ground or negative supply. To prevent all noise.
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