The ISD1820 is a sound recorder and playback module capable of storing 20-second audio recordings. It features the ability to initiate playback with a button press or a pulse, which is very useful in automated transmissions. The playback signal can be generated manually by tapping the playback button onto a radio’s PTT button, or by using a dedicated controller (such as a timer or an Arduino) for sending transmissions at regular intervals. To send the module’s audio signal to a radio transmitter such as a VHF radio on FM mode or an HF radio on SSB, connect the speaker out to the microphone line input of the radio. This module can be used to send repeated transmissions such as station IDs or for calling a CQ.
Night Sky in Focus | Astronomy and Amateur Radio © Anthony Urbano | Manila, Philippines