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The audio frequency is dictated by R1 and C1. The consumption is under 1 mA without keying and around 20 mA when the manipulator is pressed. In this way the oscillator functions continuously, and it does not change the frequency when the manipulator is pressed. The keying is done in the speaker/LED ground circuit.
Online java tonegenerator tones generator#
You can see and hear this simple audio tone generator at:Īnother simple tone generator is done with a TTL inverter integrated circuit, SN7404: They are so efficient that they are even used in street lightning. LEDs became more and more efficient in the last years, and the days when they needed 20 mA are gone. Pictures and a table with currents and voltages for common LEDs are published by me in SARC the Communicator from December 2018, page 40: They can be seen OK even at 50 micro Amps. They work fine at higher current, with a shorter life span. I made it on a breadboard, and I used a power bank with a power supply adapter: The consumption is under 10 mA and the total power is under 30 mW. But at 3 V the transistors do not run hot. After 6 V the tone changes a bit and it might be necessary to adjust the 68 KOhm resistor in order to keep the generated tone in the 800 Hz – 1000 Hz range. It works without any change from 1.5 v to 6 V. In my version of this schematics (there are plenty of versions of it on the Internet) I use 3 Volt as power supply. The first generator is a 2 bipolar transistors oscillator. I could not stop myself from re-making on the breadboard some schematics that I made many, many years ago, improve them and write an article about them. Feeling an increased interest in my area for the subject of this article, I made some simple audio oscillators that can be useful for CW practice.