#Backing up n1mm logger generator#

#Backing up n1mm logger generator#

I also drawn the schematic to show the integrated circuit in it:Д«ased on previous schematics I made a вЂњheavy-dutyвЂќ CW tone generator if your neighbors did not know you are a ham radio, this is a good opportunity to hear you and find out. It requires a very small current to pass through the manipulating key/switch: One of the gates is used to block or allow the oscillation. The 14 pins integrated circuit has inside 4 NOT AND gates. You can see it and hear it in function on YouTube at:ДЄ version of the above uses SN74HC00 instead of SN7400 (SN74HC04).

The oscillator part is separated from the speaker/LED output by an inverter buffer (the inverter between the pins 8 and 9 of the IC SN7404.

The oscillator is always powered, so it has its frequency stabilized already in the moment(s) of keying.

The rectangular signal is 50% вЂ“ 50%, while at the first generator there is a train of short impulses, something like 95% вЂ“ 5%.

The sound is more pleasant at this second tone generator because: All those 3 values work, and you should use the formula for the tone of your choice. The R1 value of 15 KOhm generates a sound of somehow higher tone in practice I tries with 68 KOhm and 47 KOhm, too. 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. You can see and hear this simple audio tone generator at:ДЄnother 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 вЂ“ 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.