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

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


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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Quick HV generator (and partial fail)

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

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

Samsung SyncMaster 940NW repair

Several days ago a friend gave me 3 defective displays that were in the dumpster at his office. They where complaining that the image was unstable, they where shutting off, etc.

That made me curios if the CCFL’s where dying or they had some power supply problems, as all 3 are very old monitors with a lot of run hours

Disassembling them revealed that at least the power supply had better days. Most of the low voltage capacitors where faulty.

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Inokim Light 2 electrical repairs

After disassembling my Inokim Light for a spring-clean-up I’ve found out that it has severe water damage inside, after running on wet roads all autumn, and getting submerged once in a deep puddle.
It looks like, because of the shape of the frame, front lid placement and the synthetic sponge used to secure the battery, water pooled on the bottom of the unit and remained there for a long time.
Also, no care was given for connector protection.

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Category: e-PushBike

Tura bucegi 28 octombrie 2018

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Anul asta nu am reușit sa ajung prea des la munte, asa ca duminica s-a ivit ocazia de a ieși la o plimbare

Vremea a fost specifica anotimpului, stabila, cald în pădure și pe unde bătea soarele, dar cu semnele iernii vizibile peste tot: gheata și zăpadă pana în pădure, în zonele ferite.

Era un strat fin de nori, dar nu suficienți cat sa oprească soarele

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Category: Munte