Monthly Archives: October 2024

Small 18650 power board

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This is a small power supply for the RF filter block project.

It takes a single 18650 cell and outputs a regulated 3.0V supply. The board also contains a cell protector.

The protection IC is a BQ29700DSER that will disconnect the cell if it’s charged over 4.275V or over-discharged under 2.800V.

The protected cell output is available on the two connection posts for easy charging

The schematic is simple – the datasheet application for the protection IC + the 3.0V LDO: 1s_board.pdf

As usual, the entire project is available on github:18650_1s_board

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Category: Electronica

RF filter block

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Since I’ve got my radio amateur license I’ve reached the limits on the band pass filters integrated in the RSP1A receiver.

My location is near some high power transmitters and they where constantly overloading the receiver’s front-end. That created a lot of false signals and a high noise base line that made HF reception difficult / impossible on some days.

To fix it, I had to create a set of band pass filters that can be attached in front of the receiver. Another requirement was the ability to electronically switch them, to reduce  the wear on the receiver SMA inputs.

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Category: Electronica, RF | Tags: