About

Hello World!

Thanks for taking the time to visit my blog. My name is Radu Motisan, and I was born in '82. I am trained as a software engineer, with a master degree in Computer Science from West University of Timisoara received back in 2007. My university years brought me in the beautiful city of Timisoara, where I live today, together with my wife.
I work as a freelancer and I have a wide interest for technology. Besides what my school years taught me (mostly mathematics and informatics), I also have knowledge of electronics, physics and chemistry. This blog shows some of the things I build, or various resources related to my research or computer programming. I also enjoy travel, reading, music and sports.
Feel free to get in contact, using the message form at the bottom of this page, or under my various articles, or drop me an email, at:
radu_motisan_email

Radu Motisan

This article has 16 Comments

  1. hi
    can you help me to make a display for power supply with 7107.
    I want shomatec and pcb
    thanks

  2. Servus Radu,

    Am o intrebare : cat ma costa sa imi construiesti acest produs [HQ] DIY High Voltage Supply (12V to 50KV) ?Am nevoie pentru un proiect personal .

    Multumesc frumos si astept raspunsul tau.

    Cu respect,
    Nicolae

  3. Hi Radu,

    I came across your blog a little while ago, like it very much, thanks. I am interested in wireless power transmission and therefore your experiment detailed in your blog. It seems somewhat different to the mainstream ideas and I have attempted to replicate your experiment.

    I made my coils okay – hard work winding them neatly but okay in the end (I like your improvised use of the CD protective disks – I did the same). Man problem is that my circuit does not work at all. Perhaps you can comment and provide a bit more detail. There are differences which I had to make due to parts availability, as follows.

    1. 460ohm resisters had to be made using a 430ohm and 30ohm in series.
    2. The diodes are UF4002, not the BYV26E.
    3. The Mosfets are IRF1405, not the IRF2007. The 1405 is the closest thing I could get to the 2007.
    4. The inductor, which I assume is vitally important is a home made one so probably not perfect. Hoping to get a commercial one soon. Can you tell me the inductor rating, type, etc.

    I am not connecting anything to the receiver coil except for an AC digital volt meter and am not seeing anything at all. I’m wondering if I need the 440nF cap in parallel with the coil to make the tuned circuit?

    I’m running the transmitter from a current limited bench power supply.

    Anyway, if you could help at all, it would be much appreciated.

    Cheers,

    Tim

    What is the in

  4. Hey Tim, could you repost this under the appropriate article? Answering your questions here would be confusing for other readers.

  5. Buna Radu,
    M-am gandit sa folosesc si eu un Dozimetru in regim online.
    De unde cumpar unul si la ce pret?
    In kit (neasamblat) nu se poate?
    Sau macar niste componente mai ieftine.
    De construit dureaza!
    Nu inteleg prea bine cum este alcatuita “Statia” completa:
    cu temperatura, umiditate, lumina, etc…
    Ma lamuresti in cateva cuvinte?
    Multumesc!

  6. Hello,

    I created an IOS app which locates a certain bluetooth device within range. I didn’t bond or connect to the device.
    Now, I would like a way to be alerted if this device is out of range. Can this be done?
    This needs to work in the background.

    Let me emphasize I prefer not to bond or connect to the device.
    Thanks.

  7. Yes. If the RSSI signal decreases below a certain threshold or the bluetooth devices can no longer be discovered, than it means it is out of range. No bonding is needed.

  8. Hello radu

    i send you an email about the electric fence against bears you posted and the problem is that it worked well at the beginning but then the second 555 starts failin until it doesn´t work at all. I added a 4148 diode at the third pin trying to protect it from the currents and the neon bulb between the coil but i couln´t find the capacitor so what do you think it is happening with my circuit? how could i protect more the ne555?

    Hope to hear from you soon. Thank you for your time. Best Regards.

  9. Hello Manuel, some coils put out more spikes on the primary circuit, than others. A completely fail-proof circuit would separate the vulnerable oscillator components from the HV side. Unfortunately I don’t have time to revisit this circuit for an upgrade, even thought I’d like to do it.

  10. hello Radu

    I finally got the hv capacitor and the circuits works perfectly now but it doesn’t give such a big spark it only makes a 0.5 cm spark what can i do to make it as big as the one you show in the video? would it be a mistake in my circuit?

    Thank you for your time.

  11. @Manuel, try increasing the current (bigger power supply) or adjust the 555 parameters.

  12. Hello Radu. I built a copy and it works fine i can send you a video or pics if you want but i feel that the spark isn´t strong enough so i would like to put a multiplier at the hv output to make it higher. What should be the values of the diodes and the capacitors to make it? Please reply me as soon as possible. Cheers.

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