Chris' Restoration Mania

 I've made a few Crystal Radio sets over the years. If you ask me, I'll be happy to go on forever about how they work, but there are a ton of online articles that are very good and I'd just be redoing others good work. One of the best articles I've read is:  https://www.jumpjet.info/Pioneering-Wireless/eBooks/useful/2008a.pdf The best resource that I've found for tutorials online is the Crystal Radio Set Society  http://www.midnightscience.com/  They have designs, and articles by others about how to make various sets. The formulas and explanations can be found here:  http://www.midnightscience.com/formulas-calculators.html#formulas1 I think one of the most useful tools is the Professor Coyle calculator pages (different website) https://crystalradio.net/professorcoyle/professorcoylecyl.shtml You can use these pages along with code your own if you wish to design your own sets.  Both of the websites have interactive web pages that allow you to calculate the de...

 I got fascinated by crystal radio sets years ago. We are extremely lucky that there are still a number of AM radio stations in the US. I've tried a number of things to make a low loss system. This will permit good reception of weak signals and also a reasonably high Q for decent selectivity. (Another post on this at a later time.) Selecting a decent germanium diode is kinda critical. I was curious to know how 1N914 diodes stacked up. How different are they.  This is an IV curve from a single 1N914 diode along with a kind of poor fit for the ideal diode equation.  Another IV curve where I tested a bunch of 1N914 diodes. It's pretty clear from the plot that they are not all equal. I choose to look at the lower end of the plot and see where the rise starts to diverge and grab the one with the maximum current at the lowest voltage.  I think to choose the best diode it is worth buying a pack of them off something like Electronic Goldmine and then sorting them. Happy hunt...

 Sorry I don't regularly blog. I do have a lot of interests and work does have a tendency to get in the way. A lot of my interests revolve around radio. To me the fact that you can transmit information in various methods using EM Radiation of any type is still remarkable to me. To that regard, I'm thinking about putting together a post on how this even works down to the quantum level.  Anyway, the purpose for this post. I'm always interested in how signals propagate. This will apply to a standard radio, but also a crystal radio. There is a nice website that will show you the estimated signal strength at your location. This particular antenna is about 2km from my house and pretty much blasts everything with radiation.  https://radio-locator.com/cgi-bin/finder?sr=Y&s=C&call=WLNA&nav=home The site shows the transmitted power, the antenna pattern and will show you the estimated field strength at your location.  Ham radio operators can get field strength meter...