Digital tape recorder. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Audio equipment
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Many shortwave players, and especially contestmen, are well aware of the problems with the vocal cords that arise during almost continuous and long (in time) work on the air. Yes, and it is problematic (without looking up from work on the air) to drink tea or coffee, smoke a cigarette. I'm not talking about eating anymore. To alleviate these problems allows the proposed digital tape recorder (DM), which has proven itself on the positive side both in terms of technical indicators and at its relatively acceptable cost (compared to branded designs of a similar purpose).
This design was created on the basis of a commercially produced in Poland designer (printed circuit board, DD1 chip (ISD1420) and documentation) of a single-program recorder and playback device with an appropriate amount of ROM stored in time (even when the power supply is turned off). The amount of ROM depends on the type of DD1 chip used - the last two digits in its designation indicate the corresponding amount (in seconds). The CM shown in the diagram has a ROM capacity for recording for 20 seconds. The current consumption is less than 20 mA.
(click to enlarge)
Its further modernization is also possible by "breaking down" one ROM program into several (for example, into four - 5 seconds each).
The CM is assembled on a printed circuit board measuring 50 x 65 mm. The microcircuit is installed using a socket.
In the design, it is advisable to use your own "recording" electret microphone (BM1). True, it is also possible to re-switch (in the "record" mode) to this input - the "basic" microphone of the transceiver, as well as operational switching to its input of the output low-frequency signal of the transceiver ("on-the-air recording" mode). It will not be superfluous to install a small-sized control speaker (BA1), which, if necessary, is turned on by a toggle switch (SA1). Potentiometer R7 selects the required level of output voltage - sufficient for the microphone input of the transceiver (this output is connected to the microphone of the transceiver in parallel).
Other governing bodies of the CM:
- SB1 - playback from ROM (while holding the button). When it is "released", playback stops and the program "becomes" to its original (initial) position.
- SB2 - playback from ROM (full playback of the program from a short press of a button).
- SB3 - write to ROM (while holding the button). In this case, the LED VD1 is on. When the button is released, the recording stops and the program "becomes" to its original (initial) position.
Program recording option:
"United Sugar Seven Whiskey (US7W), CO CQ CONTEST, QRZ"
Options for using the recorded program:
1. Using the SB1 button - only the playback of the text "US7W" (for example, when calling on a "foreign" frequency of the transmitting station - CQ (QRZ) CONTEST ".
2. Using SB2 or SB1 - to play the full text of the program (when working on "own" frequency).
It should be noted that the proposed CM may have other applications. For example, installed in a car, it can inform the driver about speeding, low battery, low fuel, etc., and can also be used in a voice repeater to identify its call sign or use it as a "bulletin board".
Author: Georgy Chliyants, UY5XE
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