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  1. HellasTechn

    Get to know each other !

    Good day friends ! I thought to make this thread to talk about each other a little more !! My friend and Πατριώτη chopnhack. First of all my name is Konstantinos (Constantine) Κωνσταντίνος in our mother language.
  2. HellasTechn

    Projects involving vintage CPUs

    Dear friends. I have been cleaning my storage room and i found my collection of old CPU's, RAM's and a few other stuff dating back from 1980 to 2000. I thought that maybe i could somehow use them to make simple circuits. (something like the arduinos). You know like led flashers etc. I even...
  3. HellasTechn

    Yamaha RX-V459 receiver/amplifier does not power on

    Dear friends Good day ! A friend of mine brought in a YAMAHA RX-V459 AV Receiver - amplifier. He says that it just stopped working. When i plug it in and press power button i can hear the input relay clicking and a few sec's later it clicks again and the device stays off. I remember exactly...
  4. HellasTechn

    Help building a 220 to 4 volts 3 Amps PSU

    Good day to all. I need to build a 220v to 4v 3A psu. Okay here is the story. On the ship that i work we have a submersible searchlight for when we dive at night. this light uses an 220v incandescent lamp. it is watertight but we have accidently broken the glass. We can not replace the light...
  5. HellasTechn

    Help identify component

    Good day. Does anyone know what this component is ? I found this in a desktop pc PSU attached somewhere at the input section and it has no markings on it. It is composed of two coils in series. I suspect that it is some kind of filter. Thanks.
  6. HellasTechn

    Digital Terrestrial Receiver PSU problem

    Good day dear friends. I have been working with the power supplies of Digital Terrestrial TV receivers for some time and to be honest i do not fully understand how they work. I do know the basics though. I came across a PSU with a blown fuse. i checked all components and they look ok. I...
  7. HellasTechn

    ESR TEST EQUIPMENT

    Good day people !!! Today i was working on a digital tv signal receiver that had a bad capacitor (inflated like a baloon). So i did a little search for a device that measures capacitors (Capacitor meter) and i came across the ESR meters that are better because they also measure the resistance...
  8. HellasTechn

    Audio poweramp TDA2003

    Good day dear friends. Once again i hould like to express my gratefulness for this lovely site. Today i am working on on building an audio power amplifier. I have chosen the TDA 2003 for this purpose because of it's low cost and the power output of 10W that it promises (that is all the power...
  9. HellasTechn

    USB oscilloscope

    Good day to all ! I was searching the web to find a USB oscilloscope to use on my laptop pc. I found a few on ebay. Does anyone know of any good and fairly cheap USB oscilloscope ? I am willing to spend up to 130 USD. What i am looking for is not a normal Oscilloscope with a usb...
  10. HellasTechn

    Problem with SAMSUNG LE22A457C1D Television

    Good day dear friends. I have this problem with my tv. When i turn on the tv the led indicator starts blinking and the tv comes on for 1-2 seconds then the lamps turn off and screen goes black. When i look closely i can see the picture meaning the tv works fine but the lamps are off. Now the...
  11. HellasTechn

    Mouse-trak (trackball)

    Dear friends Good day. I have a mouse-trak b-9pind (trackball) this is a mouse that is mainly used on servers or other control systems. The specific model (b-9pind) has an rs232 DB9 connector. The thing is that someone thought that this was useless and cut the cable and took the connector...
  12. HellasTechn

    Circuit Schematic Design Software

    Does anyone know of any free Circuit Schematic Design Software ? I just want to draw circuits easily and MS paint isnt exactly the best way to do it... I use to have the EWB software but this is more a simulator than a drawing tool. Any suggestion welcomed. Thank you very much...
  13. HellasTechn

    How to preserve 18650 batteries

    Good day dear friends ! This is my question. I have a bunch of 18650 batteries that i riped of a laptop battery. I use them in my flashlight. Now i try to figure out a way to preserve them. In other words to keep them from going dead. I have a cheap charger. My first thought is just...
  14. HellasTechn

    AND and NAND chips

    Does anyone know the commercial names for AND and NAND chips ? Example. I know that the 74LS86 is a XOR chip... What would be the code for AND chip and for NAND chip ? Or maybe there is one chip that has both ? Thank you !!!
  15. HellasTechn

    Noise filter for DC fan

    I have a small (12V) (pc cpu fan) and i wanted to eliminate the noise in introdices to the DC supply line . I think all i need is just a capacitor in paralel with the fan. isnt that right ? But what capacitance would be best ? like 10uf ?
  16. HellasTechn

    VGA to Sync on Green

    Hello my dear friends. I have a pc and a monitor that has three BNC inputs (RGB). this monitor uses sync on green. I know very little about video signals... I have tryed to make a circuit i found on the internet to convert the signals but it does not work. this is the circuit i used...
  17. HellasTechn

    Help with "Data switch"

    Dear friends. Here i am going to share with you the problem i have. I need an automatic switch. I have two GPS receivers which have NMEA output. The output connector is a DB9 Connector. Pin 2 NMEA data output Pin 3 NMEA data input Pin 5 Ground Now i need to hook both theese GPS...
  18. HellasTechn

    Greetings from HELLAS

    Good day dear friends. I am pleased to be here with you in this forum. Hope to get the chance to help you and get help from you all !
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