Author: Tom Zicarelli

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VCR’s are analog TV transmitters

Any VCR with antenna output has a built-in RF modulator.

Generally they transmit on channels 2-4. Here are the US frequencies:

from wikipedia http://en.wikipedia.org/wiki/Television_channel_frequencies

The signal is weak, not intended for broadcast. Not legal to broadcast… but hypothetically, amplifiers and antennas could be connected.

This audio signal is from an iPod playing through a VCR received by rtl-sdr in Max on 65.75 MHz. (channel 3) using a random length wire connected to the antenna output.

 

Notes about RF modulators:

I have tried this with some small RF modulator boxes. One of the problems is that you need to send a signal to the video input, or the modulator won’t run. You can get a rough signal by patching one of the audio channels into the video input jack. Or a better signal by using the video composite output of a raspberry-pi. Although the VCR gives a much cleaner signal

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High Voltage and X-Ray Experiments

By Henning Umland

http://www.celnav.de/hv/hvindex.htm

“If, for example, the capacitance of C were 1000 μF, a charge of 1 mAs would result in a voltage of 1 V, independent of any current fluctuations (the capacitor voltage varies in proportion with the charge). I use two paper/oil capacitors with a total capacity of approx. 1500 μF. Thus, a capacitor voltage of 1 V is equivalent to a charge of 1.5 mAs. The time constant resulting from C and the internal resistance of the vacuum tube volt meter, VTVM (Ri = 11 MΩ), is 16500 seconds. Therefore, the capacitor voltage remains virtually constant for some time after the anode current stops flowing. Electrolytic capacitors are not suitable for such a circuit because of their relatively high and unpredictable leak current…”

From “Building a Simple X-Ray Machine”

 

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Arduino electric eye and musical stairs

Summary of experiments with IR beam detection.

Initial testing with Radio Shack sensors and IRremote library: https://reactivemusic.net/?p=4027

musical stairs project

Built by students at Gould Academy, Bethel, Maine 2013.

Detects movement on stairs using individual IR sensor pairs on each step. When an IR beam is broken, a note is triggered and status LED lights up. Using an Ethernet shield, the data is tracked in a feed at xively.com

materials

Adafruit IR emitters and receivers

https://www.adafruit.com/products/157

https://www.adafruit.com/product/388

construction of sensor units

IR transmitters and receivers wired into terminal strips (no soldering):

transmitting unit:

schematic:

receiving unit:

schematic:

layout of stairs

Arduino connections and code

code:

[wpdm_file id=19]

(local file: musicalStairsVersion3tz2)

notes

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Pd signal streaming objects

Use streamout~ and streamin~ to stream audio over a local network

The ‘help file’ for streamout~ has an example. Change ‘localhost’ in the connect message to the local IP address of the target.