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If you are looking for an inexpensive kit build project that comes together nicely and works well to boot check out the DSO Shell 15001K Oscilloscope Kit.   https://www.banggood.com/Orignal-JYE-Tech-DS0150-15001K-DSO-SHELL-DIY-Digital-Oscilloscope-Kit-With-Housing-p-1093865.html?rmmds=myorder     At $22.00 including shipping from China this is a no brainer. With a 200K bandwidth (Perhaps a bit of an exaggeration) it is undersized for many applications but still is a good tool ...
jw0752

Zener & LED Tester

Posted by jw0752 Top Member Apr 23, 2017
While sorting out and reorganizing my collection of mostly salvaged zeners the other day I began to imagine what I would have to do to make a simple tester. In the past I have set up the power supply, milliammeter, voltmeter, and a variety of current limiting resistors to test the questionable zeners. After considering the problem for a while I decided that a custom power supply with a few modifications would make a perfect zener tester. I also realized that it would also do double duty as an LE ...
One of my Grandsons recently was telling me about a type of psychotherapy that is used to treat PTSD and other traumatic incidents called EMDR, Eye Movement Desensitization and Reprocessing. He described a machine that was being used by therapists that consisted of a light bar mounted on a tripod. The row of LEDs on the light bar would move back and forth from end to end. The machine also had hand held vibration devices that are placed in each of the patients hands and a set of headphones. Durin ...