$4 echo repeater (non-profit project)
The repeater is connected to almost any type of transceiver and is designed to issue information messages at amateur frequencies, for example, on how to open the repeater, as well as record voice messages with subsequent playback. Extreme simplicity provided excellent reliability of the device. Despite the simplicity of the circuit, the repeater has remarkable parameters that more expensive and hyped devices do not have. The repeater memory allows you to store a total of 2min (DD1 M25P16), 5.5min (DD1 M25P32) or 11min (DD1 M25P64) of audio messages (sample rate SR = 12500). One of the tasks in the development was the use of mass non-specialized and cheap SPI memory.
The setup consists of only 2 operations: setting the frequency (setting baud rate - BR = 38400bps) and setting the silence level.
Repeater circuit diagram
The repeater can be connected to the transceiver in 2 different ways: using the squelch signal (SQL_IN signal) and without using the squelch signal.
Repeater assembled on a breadboard
The simplicity of the circuit allows you to assemble a repeater without making a full-fledged printed circuit board: a breadboard or a board cut out by a cutter works just as well as a factory-made one.
Repeater inside the Motorola GM-300 transceiver
Repeater assembled as a standalone device
The main dialog box of the programmer
Software written specifically for the echo repeater allows you to fully configure the device in a few minutes. However, if desired, the device can be fine-tuned using console utilities. The memory card and details of the programming process are in the device description, which can be downloaded here.
The software installation package, documentation and firmware can be downloaded here.
A video demonstrating the operation of the repeater can be downloaded here.
Dear hams! This project is free and was done specifically for you, there are not many of you left! The price-quality ratio of this echo repeater is an order of magnitude higher than what you have seen so far. Try it - you will like it, the device is really cool (watch the video). After installation, in the target folder you will find the controller firmware with fuses, a demo assembly, and all the necessary software for self-production: you do not need to order anything anywhere, everything is on, just do it. If you have any questions - write, we will try to answer.