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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:

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

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
Cer_1
cer_2

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Category: Munte

Fixing a VORTEX 32G19

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This is a quick post about fixing a TV that had the HDMI connector melted off the main board.
Got the TV as junk – so there was no pressure to fix it.

The TV’s id numbers are ( stickers on the main board / firmware, etc):
C/N: PC07035
P/N: CV028E_V5E0_01238
D/N: 20070322X00005
M/O:J03A117
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Category: Repairs

General description

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Hello

While working on RF stuff I got to the point where I had to tune filters and measure frequency response of amplifiers and other tuned circuits.
This implies having access to a VNA.
As something like that is out of reach, and buying an existing one is out of my budget I started out designing one from scratch.
For that I’ve used the N2PK VNA as a starting point with some small changes that I though will be useful.

The entire system will have:

  1. Two AD9851 based generators, each with 2 buffered outputs
  2. One AD8302 based detector that measures phase and amplitude differences
  3. One system control board, that offers to the driving computer a SPI and an I2C interface



Each board has a 12V input and local LDO’s for all needed voltages.
12V was chosen because the value of the MMIC’s bias network was high enough to require just a generic inductor.
I’ve used 5V for all internal supplies as all chips used that voltage.
Also, I’ve used a common PCB template – so the boards can be stacked with M3 spacers.
That will also simplify making some shielded cases, if needed – just one case template.

The overall system architecture looks like this:

Category: VNA

New toy

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Just got a new toy, to start working on some interesting projects: an HP3466A almost my age, but still kicking

Here are some pictures:

[nggallery id=7]

Category: Electronica | Tags: