I Came across this old analog TV modulator in a box of stuff, so I plugged it into my digital TV and powered it up, with some audio modulation on the input. I set the switch to channel 3, and then pushed 3 on my remote, but I got no carrier whatsoever on the TV.
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From Talking Electronics. I’m not sure if this circuit can be frequency modulated the full amount for the FM broadcast band. It’s difficult to push a crystal off its resonant frequency. I’ll be trying it someday if I can find the right xtal. I would be more inclined to instead use a ceramic resonator. I
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In 1966 I completed basic training and went to Ft. Monmouth, NJ for 10 months of Radar repair training. The last half of the course we got to work on the actual Radars in *that* barn-like building in the photo. I was on the graveyard shift. There were birds flying around up in the rafters
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This is definitely groundbreaking. But I don’t understand why they’re doing it this way. I think the array that’s in space should be as simple as possible – an array made up of thin sheets of metallized mylar that reflect the sunlight to the photovoltaic array on Earth. In their system and mine, there has
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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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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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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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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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Good article on passive intermodulation, AKA the Rusty Bolt Effect. https://www.electronics-notes.com/articles/radio/passive-intermodulation-pim/what-is-pim-basics-primer.php
From FB group Building Transistor Radios 2018-09-28 I see nothing wrong with using the ‘386 to directly drive the power output stage. It’s cheaper than a transformer. But I was thinking about how the current was flowing in the ‘386’s output transistors. Normally an electrolytic capacitor blocks any DC from flowing out of pin 5.
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