Category: ideas

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LED interface for rx-320 receiver

implementation of low resolution LED interface for TenTec rx-320 receiver.

Based on this design: https://reactivemusic.net/?p=12408

download

(note: this work is in progress. The github version has not been tested)

https://github.com/tkzic/rx-320

folder: max/LED-project/

files

  • ab-rx320-g02.maxpat (main patch)
  • colorpanel.pat
  • palette.txt
  • mod_engine_d.pat
  • mod_fb_router.pat
  • panel2.js
  • rxpanel2.mxb
  • rxsynth.xml
Note the BCR-2000 preset is not yet available

hardware

  • Behringer BCR-2000 Midi controller
  • 2 TenTec rx-320 receivers
  • 2 USB to serial adapters

instructions

(in progress)

Connect all the hardware and open ab-rx320-g02 in Max.

Set the MIDI and serial ports as directed in the patch.

notes

The system uses two TenTec  rx-320 radios, controlled by Max. Here is some of the data that is displayed.

  • frequency in Hz.
  • gain
  • filter setting
  • mode (AM/SSB)
  • Passband shift
  • BFO
  • frequency calibration
  • AGC
  • Mute
  • scan-mode
  • memory presets
  • data rate (speed limit)
  • time clock
  • memory preset selection
  • 5 modulator units
  • indicators that show which radio parameters are getting modulated
  • and others…
layout
Modulator unit detail
control interface

A Behringer BCR2000 provides  User input to the radio. Here is a rough layout of the controls:

Button detail

Note there have been changes: Auto cal is now s-match

 memory preset categories

 blobs (display units)

modulator destinations (it doesn’t seem to be working like this…)

memory presets – search results:

what’s next
  • Need to clean up the control interface – build a template for bcd-2000
  • better documentation of LED interface
  • write instructions
  • more testing
local files

tkzic/max new radio project

main patch: ab-rx320-g02.maxpat

 

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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”