Power Meter
For the final project, in collaboration with another fellow student, it was decided to work on designing a power meter (power indicator) for the radio. There are multiple approaches to designing a power meter, it depends on the application and design requirements. For this radio, it is preferred to have a power meter that has low power consumption, as the indicator will be placed in parallel to the output, the speaker, the less power it draws, the less effect it will have on the quality and volume of the speaker.
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Design
For the final project, in collaboration with another fellow student, it was decided to work on designing a power meter (power indicator) for the radio. There are multiple approaches to designing a power meter, it depends on the application and design requirements. For this radio, it is preferred to have a power meter that has low power consumption, as the indicator will be placed in parallel to the output, the speaker, the less power it draws, the less effect it will have on the quality and volume of the speaker.
Multiple designs were considered and tested (in some cases), but most of these devices ended up drawing too much power, causing distortion in the circuit or oscillation due to the conductive properties of some components. In the end, the design required no more than a few resistors and LEDs at the output of the radio, who needs a transistor anyway?
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Figure 1: Design of the power meter by itself
It would be boring to look at a big circuit that has been discussed in other parts, so the full design will be omitted. To compensate, here is a cool video.
It is not shown in the video, but the input voltage is being increased (faint clicking sound) and as the input voltage increases, the output voltage increases as well, making the LEDs brighter.