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homelist of postsdocs about & FAQ


Please feel free to explore my YouTube channel for even more videos. Most of the ones I have uploaded do not include any speech/explanation, however do not hesitate to go-on and write me a message.
If you need more details e.g. documentation, circuits, firmware or general guidelines please feel free to contact me here.

My YouTube Channel


A DS18B20, ENC28J60 and PIC18F4525 Ethernet Thermometer

Again I have a separate page about this one here. However I've decided to just as well list the show-off video here. Source, schematics is availabe in the separate project page.

That's how a 600bps manchester encoded data string sounds

Some trials to create a wireless connection via the FM radio band (88-108). It was partly successful in the end after adding a schmitt trigger after the receiver, however this hilarious footage shows me, trying to make a connection by feeding-in the chinese ratio receiver's speaker output directly to the microcontroller's port (first thing to try when you only have all that garbage around you). The string sent is "Krastavica" ACSII, in Bulgarian meaning a cucumber. So, I guess there could be some gurus out there, who will be able to decode that "noise".

A fun FPGA course I had at Linkoping University

You can briefly read more about the project we did here. I am just listing a show-off video of the simple system we had.

Robko 01

During my first year at university, me, Tsvetomir, Simon and Kamen decided to give a new life to an old mechanized robotic hand produced in the late 1980s in the Factory for Medical Equipment in Sofia. The six stepper motors were originally controlled by one of the first Bulgarian 8 and 16bit computers - Pravetz.

However as these were obsolete, we decided (most credit goes to Simon) to create a new stepper motor control module with an ATMega32 instead. Here's a show-off video. There was however an issue with the mechanics, as the steel cables were not correctly threaded and thus the "robot" looks like disabled.

The Automatic Weather Station

You can read more about our automatic weather station project here. However, as I will be listing videos on that page, here are some too:

An overview of the initial "fly-around" prototype:

A somewhat more completed prototype on a separate PCB - first tests:

First tests on the pole (not mounted at full height):

Another view, now mounted and tensioning cables attached - height 11 meters.

And in case you want to see what the weather is in Ruse now:

4 x Switch Mode Fluorescent lamp inverters.

What I am presenting here is my own design of switched-mode fluorescent lamp ballasts. I was given the task to find a way to build cheap-enough ballasts (cheaper than the conventional inductor-based) to be used for the lighting of a large number of lamps on a ceiling. The whole circuit is based on a two-transistor blocking-generator using power HV switching BJTs MJE13007. A very inductor-sensitive design, the air-gap of the output choke is used as a current limiter for the tube and as I have wound all inductors myself, the air-gap of the ballast output inductor can not always be maintained the same (when using hand tools). Having problems as both BJTs going into conduction at same time instance was very probable with bad inductor winding. Quite bad pop-bang experience when this happens, as it often ruins the PCB tracks, though I had fuse protection.

Anyway, did the job, was cheap at that time (now the chinese ebay market explodes with cheap ballasts), and provided me some good more-HV electronics experience. Want to have schematics and build guidelines? - Contact me. I will try posting the schematics I had came-up with, the PCB and possibly some explanations whenever I get some time and mood.

Elektronika 2011 - The annual student hobby project elecronics exhibition at my BSc university - Ruse University

This event is annualy organized by the student's hobby electronics club at the university. All explanations are in Bulgarian, however there could be seen some of my hobby projects in the period from 2007-2011.

If you happen to not understand Bulgarian, I am basically explaining the functionality of our hobby devices.

Powder Filling Machine Test Prototype

Here's an update on the powder filling machine prototype I was trying to develop. It is quite intuitive, I was trying to use a screw conveyor, German/Bulgarian: "Schnecke/Шнек", as a filling mechanism. The idea was to have a strain gauge measuring the amount of material falling into the package and actively controlling by PWM the DC motor's speed. I was using an "el cheapo" resistive tensometric strain gauge (a wheatstone bridge kind-of) feeding it directly to an AD620 instrumentation amplifier. The amplified analog voltage was fed-in to the PIC's ADC and was oversampled to get some more stable readout (too noisy/fluctuating otherwise). A simple linear control algorithm changes the PWM accordingly, until a desired weight (AD-in amplitude is reached).

Surprisingly it was accurate up-to plus-minus 5 grams, for a set weight of 50 grams, offset and gain calibrated in advance. The aim of achieving plus-minus 1 gram was too optimistic, as the whole mechanical system was very crude. Possibly a lower-step screw would have somewhat improved the whole system.

PWM using PIC18F4525

In 2010 I had a task to find way to control a two-pole DC motor quickly enough. The whole control module (to be developed) was supposed to be used in the dosage apparatus of an automatic packing machine (to be developed) and provide an active feedback for the dosage system. One of the above videos shows an example of the test dosage prototype. This video below practically shows a PIC MCU, controlling the DC motor using a 1 kHz PWM. Nothing special/very intersting, however it may suit as an inspirational video to newcoming electronics hobbysts.

"Atmosphere" in the "Chamber" - An old East-German RC Generator Repair (fun, fun, fun!)

I'll leave out any comments here :)

Neon Tube Ring Oscillators

I guess you've never thought that it is possible. Dekatron counting tubes are basing on a somewhat similar principle. Ronald's electronic project site is explaining the principle very thoroughly.

HV fun with a color TV flyback transformer

Nothing special here, besides the joy and fun such a simple circuit can give you.

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