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Many of the small electronic gadgets that I use daily, cameras, labeler, and test equipment, do not tolerate battery voltages below 1.4 volts. As a result I have always quickly accumulated a lot of AA batteries with voltages around this level. When I counted the other day I had over 40 such batteries. Traditionally they have gone out with the recycling. This time however I decided to do a little experimenting to see if I could capture and use some of the remaining energy. A wealth of small DC to ...
When I left Part I of this blog, about the building of a small portable Crystal Tester and Frequency Counter :   https://www.element14.com/community/people/jw0752/blog/2016/04/08/economy-frequency-counter-crystal-tester ,   I had just latched up the input RA4 of the PIC 16F628 microprocessor. This was caused, as usual, by ignorance on my part. A more thorough understanding of the PIC revealed that its inputs would not tolerate voltages below Vss.   This circuit, originally d ...
While checking out the source of all things economical I came across this frequency counter kit and crystal tester.   http://www.banggood.com/1Hz-50MHz-Crystal-Oscillator-Five-LED-Display-Frequency-Meter-Kit-p-959592.html   Yes the price was only $7.45 and they insisted on shipping it for free. I did not expect much, but for $7.45 there is nothing to loose and if I could make it work it would be handy for testing salvaged crystals and showing the frequency of some of the little oscil ...