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:

IEI ACE-R150 fan replacement

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Some time ago I got an old QNAP NAS that uses two ACE-R150 power supplies in a redundant connection.

They where noisy from the start and they got worse as they drew in extra dust from the CNC machine, to the point where I could no longer work with the NAS powered on.

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Category: Electronica | Tags:

AL8843 led driver board

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This is a quick build around an AL8843 step-down led driver from Diodes inc

It uses the reverse buck topology, where the switching mosfet is referenced to ground, and the output is referenced to Vcc. This works well for loads that don’t need a ground connection – LED’s for example.

It also simplifies the chip internals because there’s no need for a floating gate driver and a charge pump to power it.

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Category: Electronica | Tags:

3s-5s BMS based on BQ77904 and BQ77905

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Lately I’ve been building some custom battery packs and I’ve been unlucky with the cheap BMS boards.

That’s why I’ve decided to build my own – something that could work stand alone and provide basic protection.

For that I chose the BQ77904 and BQ77905 from TI.

They have all the functionality that I need and they can be chained to create up to 20S packs.

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Category: Electronica | Tags: , , ,

BQ76920 AFE board

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Hello,

This post is about a new project that i’m using as a start-point for a bigger one.
The final target will be a BMS system for a 10S or 15S battery, like the one that’s used in electric bikes / push-bikes

After checking the datasheets and the available parts, I’ve decided to use the following system setup:

I’ve decided to start with a 5S chip for 2 reasons: I had a 4S pack available to play with (a pack used for a modified car vacuum cleaner) and because I wanted to limit the amount of available energy and potential damage if something went wrong.

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Category: e-PushBike, Electronica, Proiecte

Quick HV generator (and partial fail)

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I was bored while waiting for some other things to finish and I remembered I had some high voltage transformers pulled from some scrapped laser printers.
They have two coils, one at around 100uH, the other at over 40H. I’ve always wanted to try the MOSFET based push-pull resonant converters and they where the ideal candidates

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Category: Electronica | Tags: , ,

ADSM302 battery mode

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Some time ago i got an ADSM302 digital microscope to replace the aging metallurgical microscope I’ve been using for the last 10 years.
Here are some links about it, and some short clips of my own:

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Category: Electronica | Tags: ,

IV22 clock software

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This post discusses about the basic software architecture as it at the publish date. I’ll update it as things change over time.
I’ve decided to use the Arduino environment for it’s existing libraries.

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Category: IV22 clock

IV22 clock hardware

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Some time ago I got my hands on some IV22 VFD tubes.
They’re quite large 7 segment displays with the specific greenish-blue color

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Category: IV22 clock
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