Practice Oscillator
Practice Oscillator
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Ramsey UT5 Universal Timer Kit $9.95 Need a little kit that will add a time delay, keep something on for a preset time, provide a series of timing or clock pulses, or even act as an audio oscillator for tones or code practice? This popular kit uses the 555 timer chip and adds extra features like negative or positive pulse triggering, on-board timing pots and capacitors, and complete instructions on how to use and apply this timer to ... |
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Ramsey CPO3 Code Practice Oscillator $14.95 Looking for a great starter kit to spark the interest of you future engineer? This little code practice oscillator is easy to build, easy to use, and features an audio tone adjustment for your listening pleasure. Using the ever popular 555 timer chip and the straight key paddle you are in full control of the output tone length and pitch. Handy 9 VDC battery operation insures hours of enjoyment and... |
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Morse Code Experiment $8.95 Long before there was e-mail there was Morse code! This communication system of "dots and dashes" still fascinates. Kids assemble the device, then use it to send "secret messages" to their friends. Historical science fun!... |
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Trading with Oscillators: Pinpointing Market Extremes -- Theory and Practice (Wiley Trader's Exchange) $22.39 The first new book in a generation to focus on the practical applications of trading with oscillatorsOscillators are an essential group of indicators that futures, options, and stock traders have embraced to reveal turning points in flat markets. In this pioneering book, Mark Etzkorn, Associate Editor of Futures magazine, comprehensively discusses the purposes and uses of such important oscillator... |
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Morse Code Signal Set $0.64 ... |
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Your Introduction to Morse Code $14.95 -- Don't just learn the code--master it! This set includes two audio CDs (for your audio/music CD player) with nearly 2-1/2 hours of practice. Learn the Morse code at 5 words-per-minute. Follow the proven ARRL Morse code teaching system.Includes 2 audio CDs and instruction booklet.... |
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Ramsey CW7C CMOS CW Keyer Kit $34.95 Add to your CW fun with our low cost CMOS Keyer Kit. Youll send clean code thats a pleasure to copy; self completing dots and dashes with properly weighted spacing and timing are all programmed into the CW7s design. Assembly of the keyer is fast, easy, and fun. Our step-by-step instructions lead you to a finished unit in only one evening. For beginners the CW7 makes an ideal code practice oscillat... |
TV detector van detector?
We are led to believe that TV detector vans work by detecting the local oscillator in a TV set.
If the receiver in the detector van is a superhet (and it probably will have to be, to pull in a signal of a few milliwatts coming from a sub-optimal antenna), it will have its own local oscillator; and if the I.F. is small, then its antenna should be good enough to radiate the L.O.
So would it be possible to build a "TV detector van detector" which cuts off the power to your TV set as soon as a detector van comes into range?
Alternatively, I guess you could build a TV receiver with a TRF frontend (like the very early 1-channel, 405 line sets) so there is no L.O.; this would be "undetectable" but not sure how well that would work in practice (625 line pictures are broadcast on UHF).
I'm not sure that TV van detectors work in this manner. I think that you will find a spectrum analyser hooked up to a wideband yagi uda.
The operator would then hunt for peaks using the spectrum analyser.
Now you are correct in that the spectrum analyser is basically a superhet with a sweeping oscillator, but the problem comes in detecting the oscillator - as it's sweeping.
If you want to be TV detector proof, then
1/ ditch your CRT, this will get rid of the LOPTX and HF ccts that a detector van may look for.
2/ Replace your CRT with a LCD.
3/ Open up the LCD and remove power to the LO, disabling rf reception.
4/ Obtain a signal from cable, or via the internet. Satellite dishes are a bit of a give away.