Vacuum tube technology dates back to the time of Thomas Edison and the light bulb. Should you decide to tackle it, I can promise you many hours of fun both in the building and in the listening for distant radio stations. In this article, I will describe how to build and operate the broadcast band version. The radio I built turned out to be one of the best ever. A few years ago, I stumbled on an unusual regenerative design that operated on 12 volts - not the 100 or more of conventional tube designs. Most of the designs used a regenerative circuit invented by Edwin Armstrong in 1912. I am embarrassed to admit how many hours I spent trying to build radios based on these wonderful articles. I particularly remember a shortwave design with the intriguing title “Europe on One Tube.” Add to this a small book of radio projects compiled from 1940’s issues of Popular Science Magazine and I was provided with many hours of experimentation and fun. His shop was strewn with all kinds of electronic parts. When I was growing up in the 1950s, my dad dabbled in radio/TV repair. The radio is made using readily available parts, it operates on 12 volts making it perfectly safe, and it offers amazing performance for a simple one-tube design. The result was an exciting and fun project that I wanted to share. These consist of "new old stock" left over from 50 plus years ago, and many newly manufactured in modern plants world wide.Ī past NV article describing how to revive an old tube amplifier inspired me to dust off my memories of past tube projects (some from 40 plus years back) and build a one-tube radio. ![]() Today, many vacuum tube types are readily available and at reasonable cost. Not only did the lowly vacuum tube make it into the 21st century, it is now on a noteworthy rebound. The former were enamored with the sound of tube amplifiers, and the latter wanted their electronic equipment to survive a nuclear attack. ![]() It should have bitten the dust long ago but that just did not happen, thanks in part to electric guitar enthusiasts and the Soviet and Chinese militaries who kept using them. So, find out yourself if it is legal in your country.Ĭlick here to see all the images of this project.In the fast moving world of digital electronics, I find it incredible that the vacuum tube - a piece of early 20th century analog technology - has managed to survive. Please remember that FM operates at 88-108Mhz band and it is illegal to make FM transmitter in many countries. You can also transmit your voice using the electret microphone. You can connect the transmitter to your computer or any other audio player and hear the transmitted sound on your FM radio. This image shows how to connect the wires to the stereo jack.įinally, connect the antenna (20 cm long wire) to C6 (30pF). Connect black wire to the -ve terminal of the battery and the red wire to the one of the 33 Ohm resistor, you can connect it to either R4 or R5. See this video- how to connect pins on electret microphone.įix the stereo jack on the strip board. There is a solder mark on the microphone, that terminal is -ve and it should be connected to -ve terminal of battery. See here how to connect electret microphone. Please remember that the polarity should be correct. One pin of the microphone goes to the negative terminal of the battery and the other connects to C2(0.1uF). I have connected it to the second line from the right. So, you can connect one pin of the capacitor to any free line. ![]() Then, fix 30pF (C6) that connects to the antenna and the collector pin of transistor. One terminal of both the resistors should connect to C2 (0.1uF capacitor). Then, fix R4 and R5- 33 Ohm resistors as shown on the image. After connecting C8, it is not necessary to connect C1 because both have the same purpose in the circuit. One terminal of the capacitor is connected to the +ve and the other to the -ve terminal of battery. Now, solder C8 (0.1uF- code 104) capacitor.
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