Two Tone Audio Generator: Part #2 

Your 3D printed spacers (with anti-rotation features--let's not forget those) are brilliant. Thanks for that great idea.

I do the same but don't cut the holes in the labels as I also print the centre point of all holes, this means that it also acts as a drilling template. All nuts and bolts then also help hold the glued label to the metal work. And as a plus side the holes always align.

I like the advantages of PNP MOSFETs, for reverse polarity protection. For the bottom edge of the front label... Maybe 3D print a "L" bar the length of the width of the face plate. Add/print feet at both ends of the bar. Place the bar over the label and under the bottom. Attach with Shoe Goo adhesive. This will prevent catching the edge of the label and peeling it off and provide feet to tilt the face upward. I love your 3D pot and switch brackets. I imagine you will have started a trend.

Had my 2 tone generator go intermittent and die on one frequency. One of the wire ended lamps had a fractured wire. Using the ARRL design, I found a frequency slope when using low Z output. (600 ohms). The capacitor on the last opamp output, needs to be a larger value, or it generates its own slope, when the low frequency is used.

Heads up, I have had numerous Duracell batteries leak on electronics in the last 3 or 4 years. This included my Fluke 77, Simpson 260P, a Ten Tec Paragon which lifted lans on the logic board, not to mention 2 remote controls. I am having no issues with the Duracell Pro batteries, at least not yet. This is a shame since I have used only Duracell batteries for years and never had any issues. Some were purchased on Amazon and may have been counterfeits. However, others were purchased at Walmart and also leaked....Perhaps, you could pull them from your 2-tone tester since this is not a daily driver piece of test gear. In my Ten Tec Paragon, I, 3-D printed a small box with lid to contain any possible leaks. Good luck es 73, Glenn WA4AOS

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