Category Archives: Proiecte

Rohde & Schwarz SMS Teardown

Hello

This is a quick tear-down of a Rhode & Schwarz SMS frequency generator, with the 1040MHz option installed.
I had to replace all the electrolytic capacitors, as they are failing all over the unit. The PSU ones blew up and filled the unit with electrolyte vapors.

The photos are quite poor and the colors are a little off – i have some warm LED lights that look good but mess up photo cameras.
I had to take the photos at F2 -> the DOF is low and there’s a lot of fringing. I’ll try to improve them as much as i can ( sharpen, etc )

front_pannel

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RF power meter (part 1)

Lately I’ve been interested in some RF stuff.

The “goal” is to build an entire RF spectrum analyzer with a range of about 50-100MHz.

For this I have to learn basic stuff like filters, oscillators, amplifiers, etc.
This implies having some basic tools like an oscilloscope, RF power meter, signal generator, etc.

The oscilloscope was already present so I’ve build a simple RF power meter using an Analog Devices log amplifier: AD8307
AD8307 datasheet

The device uses the basic connection – figure 32 from the data sheet. The INP signal is connected to a 50 ohm terminated BNC input via 100nF capacitor.
The INM pin is connected to ground via another 100nF capacitor.

The output signal is fed to a LM358 op-amp connected as a buffer. The op-amp output goes via a RC filter to the output.
The entire RF section is build dead-bug style in a small enclosure made from FR4 pieces. I’ve run out of space on the base plate, so I had to build it in a “3d” fashion.
Here are some pictures:

IMG_0217
IMG_0220

The read-out is based on an 4×20 lines LCD display driven by a STM32F0 board. The detector’s output is connected to one of the ADC’s input.
The microcontroller code samples the ADC, creates a buffer containing 256 values from witch it extracts the Min / Max and medium values. The displayed values are updated around 2 times / second.

I’m still working on the code. For now i’ve created a simple calibration table in 50Mhz steps, from 50 to 500MHz.

80C552 board

Hello

New toy – a Philips PCB80C552-5-16WP based single board computer.

The board is designed to have 64KBytes of EEPROM from 0x0000 to 0xFFFF, 32KB of SRAM from 0x0000 to 0x7FFF and 32KB of peripherals space from 0x8000 to 0xFFFF

On the same board I’ve placed a SPI RTC, EEPROM and 4.096 voltage reference for the on-chip ADC.

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Category: Electronica, Proiecte

RGB led lighting module update

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top layer

Hello
This is an update for the led lighting project.
The design in complete and the PCB’s are almost ready.
This is the schematic:

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Ceas cu afisaj VFD

Ca o prima postare am ales un proiect mai “aratos”: un ceas cu afisaj VFD

Pentru afisaj am folosit un tub IV-18:

IV-18 tube

IV-18 tube

Caracteristicile tubului sunt:

  • 9 digiti, 8 cu 7 segmente si virgula, 1 cu simboluri speciale.
  • tensiune de filament : 5V la 85mA
  • tensiune anodica: 20-30V
  • curent de grila: 11mA per digit
  • curent anodic: 8mA per digit, cu toti anozii aprinsi

Mai multe informatii puteti gasi aici
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Category: Proiecte | Tags: , , ,