Archive for the ‘Radio Frequency’ Category:

2022-03-12 Homemade Adjustable Capacitor

Homemade Adjustable Capacitor I read that the 365 pF air variable capacitors are very expensive, $30 or more so I decided to try to build one. It’s not difficult to make an adjustable capacitor out of materials one may have at home. This one does not adjust easily, it’s more of a prototype. I got

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2022-01-03 Periscopes Replaced By Video Cameras

I’m sitting on the grass in the back yard and it’s chilly, but the sunlight feels really good on my back. I can hear some birds up in the trees, I’m waiting to see if they’ll come down and eat some birdseed. I started thinking about a way to watch them up there. What I

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2021-12-06 MP3 Player To FM Radio Link (Mono)

MP3 Player To FM Radio Link (Mono) This circuit allows you to play your MP3 or any stereo audio source into a mono signal for reception on an FM radio. It has no antenna and has a range of a dozen or so meters. It operates off a 6 volt rechargeable Ni-MH battery pack but

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2021-09-11 The Notorious Russian Woodpecker

For years the HF bands were filled with RF interference that would appear at a frequency for a minute and then jump to another frequency. The direction the pulses were coming from was the Soviet Union. There was no way to stop the interference; the Soviets were ignoring complaints. This YouTube video tells about it

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2021-06-14 Electric Vehicles Are In Stealth Mode

I have a PIR (passive infrared) motion sensing light on my porch for more than a year, and I’ve noticed that it can sense some of the cars that go by. If the car has been running, like coming home it will usually trigger the light. But when a neighbor starts the cold car and

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2021-04-30 Circuit Won’t Oscillate At UHFs

From FB post Apr 29 Joshua E. Hrouda I trained on Radar repair in the Army, and since then I’ve known that circuits with ‘lumped constants’ have problems with parasitic capacitance and inductance above a few hundred MHz. But I experimented with this circuit anyway. I think Colin should say, instead of ‘tight’, that the

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2021-04-28 Colpitts Oscillator For FM BCB

This is a low power oscillator using an air core coil and silver mica capacitors for stability. Parts values are subject to the frequency needed. There is no modulation. For FM the 10 pF capacitor would be lower and include a reverse biased diode as a varicap in parallel. The audio should be across this

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2021-03-24 The New 5G Is Safe

This should not be necessary to continually debunk a myth that should be dead. https://www.sciencealert.com/major-review-still-finds-5g-technology-to-be-completely-safe

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2020-08-03 Wireless Power Transmission In NZ

2020-08-03 article says it uses the industrial, scientific, medical frequencies. Tesla Redux! << NZ to trial world-first commercial long-range, wireless power transmission >> https://newatlas.com/energy/long-range-wireless-power-transmission-new-zealand-emrod/

2020-06-18 Michael Pupin & Patents

From the list of his patents in his wiki. Armstrong co-authored some patents. https://www.google.com/patents/US1416061

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