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Dual tone audio oscillator

This page was last updated : 14-Sep-23 18:05:47

A few years ago I made simple tone audio generator which I used to test and fault check my ILER20. Recently I needed it again on a other project but couldn't find it back (maybe it went into a junk box or got given away), so I wanted to build another one. VK3YE has on his website a very nice simple version which generates 1.1Khz and 2.2Khz (schematic) and can also be used as a dual tone audio oscillator. The basis for his design is a circuit from the book "Solid State Project for the Experimenter" by Wayne Green.

So I printed the schematic from VK3YE and started skribbeling for a manhattenstyle construction on a pcb to be used with my Altoids tin 9V holder with switch. 

 

When that was done, it was time to glue the pads on the the PCB. As you see I used a different setup the potentiometer. 

A bit of fiddling around and everything was in place. Including 2 leds to indicate which oscillator is active. 

I wired the Altoids tin 9V holder with switch to use 2 switches so both could power a oscillator. 

Every thing fits nicely in to the peppermint tin. 

And after some testing I added a ground loop, a 2 pins header and a phone chassis part on a small 3D printed bridge. The output is variable with the potentiometer and the plastic shaft can be stored in the tin.

Update 

And the big fun of hamradio is that you modify stuff  when you have new idea's. My idea was to have 2 levels which can be preset and switched.

So I removed the big potentiometer and installed 2 smaller ones (100K and 10K), a 3 pins header (for the jumper) and a extra resistor (150K connected to the 10K for the 2.2 Khz signal path).

For setting up the 2 levels I used my oscilloscope.  

The 1.1 Khz signal.

The 2.2 KHz signal.

The mixed signal.

 

Schematic inlay

I redrawn the schematic so I could use it as a schematic inlay for the tin. You can download the PNG image below or download the SVG file. 

Now I can't lose the schematic and specifications again (atleast when I have the tin).

 

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