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Juhani Repo Address: Jampankaari 17 A5, 04440 Järvenpää
Phone: +358 (0) 445 447 133
E-mail: [email protected] LinkedIn: https://fi.linkedin.com/in/juhani-repo-490b4383
I see I have caught your attention
The purpose of my project portfolio is to show you a glimpse of my hobbyist background with electronics and embedded systems. Hopefully taking a look at it makes you curious
By now, you have seen my formal background and talents in my LinkedIn profile.
Therefore this presentation is a bit more open-minded, it´s style is relaxed and casual.
Now here´s a contraption I´m quite proud of. A remote controlled robotic vehicle, inspired by a back then popular TV Show ”Robot Wars”. It consists of old bicycle tires, power drill motors, chains and some gearwheels. Mechanically very difficult thing to build, but a very educational one as well. And in the end, it sure earned the honor of being my thesis in the vocational school all those years ago.
It´s just mandatory to have a case for the robot electronics equipped with a viewing window. In the middle you can see the servo motor mechanically attached to the switches responsible for the reversing the driving direction. Located next to that there is a radio receiver. Though motor driver circuits are not visible, you can see some relays responsible for direction reverse and such on top.
Mechanical power to drive the robot is provided by two cheaply manufactured power drill motors. With the built-in crake disassembled and the chuck steadily supported, straightforward gears are utilized in order to gain enough mechanical strength to make the robot move, with the minor decrease of speed. The entirety was put together through many attempts and failures. In a grand scale, mathematics wasn´t exploited.
The second robotic vehicle, built about two years after the first one, provided all the mechanics in advance. It is built into a molded aluminium chassis of a former moveable X-Ray unit, possibly originally utilized in a hospital and retrieved from a junk yard. This time an AVR based embedded program translates the signal provided by the radio receiver to PWM signal to control the motor drivers.
The battery compartment within the vehicle provides two lead gel batteries for each motor and one for the logic section. There is also an in-built mains transformer for charging directly from wall socket. A charging system electrically disconnects batteries from motor driver circuits while charging takes place. On the right side of this picture you can see the user interface, consisting of an LCD, some switches and pushbuttons.
All the electronics are laid out, only some wiring left to do. Middle of the foreground you can see the motor driver circuits, circuits to unlock the solenoids within the motors and relays responsible for direction reverse. Underneath them there are relays to disconnect the batteries from the load for the time the charging takes place. All the PCB:s are still homemade.
This Self-made Digital clock provides an easily readable time from across the whole room. This AVR-based embedded system exploits a DS1302 real time clock and very big 7-segment displays. Over time there happens be a minor fall behind phenomenon present with seconds but it shouldn´t hurt anyone. This thing also provides a nice night light should you be afraid of the dark
The clock has a rather simple user interface once you get to know it. There is a setup mode, which allows you to input the time/date one display at a time. Naturally it´s taken care of that one cannot input an impossible time/date information. A wake up function is provided which plays a little melody when it´s time to go. Brightness of the displays can be adjusted in few rough steps.
”Digital Multi Effects Unit” originally designed by Hubert Bollig (Germany) and published in Elektor Electronics magazine in September 2010. This adaptation, in which the original stereo design was shrunk into a mono version, was my very first industrially manufactured PCB. It taught me the principal design rules and also the basics of soldering SOIC-encased SMD:s by hand.
As a thesis of my bachelor´s degree I designed and built a ”Running Text Display”, like ones you can see in many places around you. Based on dot-matrix displays and multiplexing, it utilizes many internal peripherals, like a realtime clock, a temperature sensor and connection with a PS/2- keyboard. Granted the original goals were not fully achieved, but the personal educational value was immense.
The user interface of the running text display consists of an LCD and a set of function keys. There´s a separate clock available and one dotmatrix display to allow the users to design own symbols to be included in the running text. There are also connectors for the PS/2-keyboard, an RS232-port for external controlling and ISP connectors for the future software updates.
Rather simple PCB design for the microcontroller of my thesis project. The purpose here was to create a somewhat universal controller board which could be applied in other projects as well. That is why there are empty places for few other AVR chips and no peripherals. Connections are given out as flat cables and screw connectors. Designing this board taught me the basics of quad layer design.
The user interface module in the thesis project was designed in such a way that only components related to the user are laid out on the top side. These include mainly displays and connectors. In order to install the PS/2-connector upwards it is glued and wired to the PCB. The RS232-serial port and pushbuttons are meant to be mounted to the case and wired back to the user interface board.
The user interface module is not meant for the serial production, therefore all components are laid out through hole by hand. Granted, this board should have been designed using four signal layers, but at a time the beforehand selected manufacturer was only able to produce single- or double sided boards. Connections with the controller board are organized by ribbon cables.
People always build and manufacture replicates from their favourite movies. This project was inspired by the classic scifi motion picture ”Back to the Future” (1985). It is supposed to be the device central to one of the movie´s main plots. It´s called ”The Time Circuits” and they consist mainly of three sets of LED-displays, a keypad and some other peripherals. Maybe someday this prototype gets an updated successor.
Once you turn the lights off, this thing gets a bit more attention. The red displays indicate the destination time, green ones tell the present time and the yellow ones point out the last time departed. Some compromises to the movie version had to be made, like using 7-segment displays instead of 16-ones, but this gadget acts out like it did in the movie and even provides some original sound effects.
Just how should I call and describe this contraption? Built entirely out of junk, it has so many gizmos and gadgets. What´s the purpose of it, you might ask? Well, it blinks lights, makes noise and is just wacky to look at. It was mainly built as a groundbreaking self educational hobbyproject without a final destination or purpose. In the end, I guess one can call it just a Wonder Widget .
Electronics being a long term hobby of mine, I began tinkering with this thing maybe around 8-9 years of age and decided to put final touches to it in 2003, at the very young age of 15. Building this contraption with the educational (and foundational) help from my father sure took a long enough and taught me lots of basics of electronics. Should tell something about my innovativeness and perceverance.
Juhani Repo Address: Jampankaari 17 A5, 04440 Järvenpää
Phone: +358 (0) 445 447 133
E-mail: [email protected] LinkedIn: https://fi.linkedin.com/in/juhani-repo-490b4383
Thank you kindly for taking time and having a look at my Project Portfolio and especially my LinkedIn profile. I hope I´ve left you curious and even a bit impressed
If you have work offerings or anything you´d like to discuss about, I´ll be glad to get in
touch with you.
P.S. Now that you´ve seen what I´m
capable of, I´d really appreciate it if
you take two seconds and endorse
me in my LinkedIn profile Thanks!
