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    Closed: micto-tel 1200 receiver additional help

    Hi I did not know how to post in this thread after so long https://www.edaboard.com/showthread.php?382299-micro-tel-1200-service&highlight=1200 so regarding this receiver, I noticed that there is no...
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    Closed: Re: HP 54520A Blown Fuse Problem

    UPDATE
    I think I have found the problem. It seems to be indeed these gas discharge tubes. Then I remove both of them completely there is no blown fuse anymore. I have never thought these can fail,...
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    Closed: Re: HP 54520A Blown Fuse Problem

    Can it be the gas discharge tubes near the big electrolytics? These are the only components I have not changed in the HV side. If they fail they could short circuit the output and thus blow the fuse....
  4. Closed: Re: How to unballance this single balanced mixer?

    I suspect that if I apply 9v DC through a limiting resistor (say 1k?) in the left points of the diodes, one diode will conduct DC to ground whereas the other not. So it will be effectively one diode...
  5. Closed: How to unballance this single balanced mixer?

    Hi, how can I unbalance this single balanced mixer so that it can detect AM on down conversion or produce AM if used in up-conversion in a direct conversion transceiver?
    LO is connected to the...
  6. Closed: Re: Passing both DC and pulses through a toroid?

    So a big transformer core that is saturated less easily, would allow DC to pass from the primary to the secondary?
    That's really new to me, if I understand this ok!

    - - - Updated - - -



    If...
  7. Closed: Re: Passing both DC and pulses through a toroid?

    Thanks a lot!
    Please help me understand the thing with my second question, if the DC is in one direction in one primary winding (assumming no saturation) and if my 0-5V edge is at the opposite...
  8. Closed: Passing both DC and pulses through a toroid?

    Hi,
    Suppose I have a toroidal core and I wind one turn of wire through it, as my primary.
    My secondary is also one turn through this core.
    For the next description assume no core saturation at...
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    Closed: At45db041b vs at45d041

    Hi I have a AT45DB041B connected to the ICSP of the atmega644 and stores data ok.
    I am trying to replace it with the through hole AT45D041 which seems identical to me apart from the 5v requirement,...
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    Closed: Re: HP 54520A Blown Fuse Problem

    I have removed the common mode choke and put wires in it's place. Fuse still blown :( At least the thermistor did not blow, but it may be lust luck.

    I remember I had tested the external RFI...
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    Closed: Re: HP 54520A Blown Fuse Problem

    Hi,
    the problem was not the bridge :(
    after a few seconds or tens of seconds it blows the fuse.
    I have located the problem in it's switching mode PSU module, because when I disconnect it from...
  12. Closed: Re: FSK 1200baud discrete "modulators". What do you think?

    Hm...
    So 3 basic problems have reported to me. One is the phase (which based on the paper, could be ignored with suitable detection scheme), the other is the effectiveness of the detector when...
  13. Closed: Re: FSK 1200baud discrete "modulators". What do you think?

    I should have posted the whole "modem" block diagram before I got you into trouble. Here it is. The RX will use two narrow filters and a simple detector which will convert audio tones to voltage...
  14. Closed: FSK 1200baud discrete "modulators". What do you think?

    Hi
    I want to investigate the possibility of making a discrete FSK 1200 baud modulator operating from 5v and connected to the TTL UART of an MCU. The circuits have to be made as simple as possible...
  15. Closed: Re: Reducing 10K lineat potentiometer to 1K, what about lineatity then?

    are you sure? This is the circuit. The mentioned linear pot/resistance will replace the 47k log one in the circuit.
  16. Closed: Reducing 10K lineat potentiometer to 1K, what about lineatity then?

    Hi I have a 10k linear potentiometer with center detent (lock).
    If I connect a 1k parallel resistor to the potentiometer ends (carbon track ends), I could in theory reduce the value of the...
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    Closed: Re: USB to PS/2 adapter, how does this work?

    I have 3 of these converters, 2 of them are actually for mouse. They all worked with one of the two keyboards. In the other keyboard none of them worked. If they had a converter inside them, I would...
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    Closed: Re: USB to PS/2 adapter, how does this work?

    I have tested it. I took a USB keyboard that I had connected to a PC through a usb to PS/2 adapter and pluged it in the project. It has been powered up (three leds are on in the beginning and then...
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    Closed: Re: USB to PS/2 adapter, how does this work?

    The purpose would be that every USB keyboard could work in the PS/2 port.
    I wondered so, because if that was the case, then USB keyboards (not-combo) would work in a PC PS/2 but not in my project.
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    Closed: Re: USB to PS/2 adapter, how does this work?

    Well this are great news for the project. If the intelligence is inside the keyboard, then USB keyboards can be used with this project IF they support the PS/2 protocol.
    I guess the simplest thing...
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    Closed: USB to PS/2 adapter, how does this work?

    I have an MCU project that accepts PS/2 keyboard. I want to investigate if I could use USB keyboards as well with it using these USB to PS/2 adaptors.

    I think that the conversion from USB protocol...
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    Closed: Re: why FM is not used in shortwave?

    I see. It reminds me the digital voice ham radio modes. It uses also multiple carriers. It seems that digital signals go that way (using multiple digital data streams within the same "channel").
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    Closed: Re: why FM is not used in shortwave?

    Yes I should have corrected the topic title, I meant except CB radio.
    Is DMR FM modulated? I thought it was AM. Something like QASK or similar.
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    Closed: why FM is not used in shortwave?

    why FM is not used in shortwave?
    This is a long question I have. Whenever I switch the HF radio to FM, AM stations carriers are received more clear. Of course I am only hearing very low demodulated...
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    Closed: Re: HP 54520A Blown Fuse Problem

    I think is is the bridge rectifier. After I deslodered it, no fuse was blown. I have replaced all other parts except the varistor and the fuse was always blown. So it must be the bridge.

    This is...
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