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  1. ramussons

    Ratings for AC vs DC devices

    I think, as long as the DC Current is not interrupted by this device, there should not any issue. AC has a Zero crossing point where the current drops to Zero and that ceases the current flow. In DC, such a Zero does not occur, and there will be a Spark, or even an Arc depending on the current...
  2. ramussons

    Walky Talky (no internet required!)

    What is the end equipment? If it's going to be an Addon hardware, it will be a deterrent.
  3. ramussons

    Walky Talky (no internet required!)

    The site mentioned mentions "business groups". It means only those in that group can communicate with each other. As I understand, you don't need a "server" or a "centralised control" to establish links - you only need a data connectivity. On the face of it, it seems to be a viable alternate...
  4. ramussons

    VHF/UHF Receiver noise

    I don't think the frequency range has anything to do with the hiss from a fm demod with no input. Back in the late 70's there were cordless phones using fm on the 1700 KHz band. Disable the squelch and see the result. I just confirmed it.
  5. ramussons

    Walky Talky (no internet required!)

    How about a "Closed User Group" for voice services?
  6. ramussons

    VHF/UHF Receiver noise

    Most FM detectors have a "Squelch" mode when there is no carrier to prevent a blast of noise. AM detectors do not have this. The noise from a AM detector is mainly "crackling" while that from the FM is a "hiss"
  7. ramussons

    VHF/UHF Receiver noise

    The "No carrier" noise depends on the type of demodulator. In general, Shortwave or AM demodulators are Amplitude Modulation detection, whereas the VHF / UHF are Frequency Modulation detection. By the basic working principle, FM discrimination (demodulation) gives white noise when there is no...
  8. ramussons

    Pulse Generating Circuit

    You need a 2 Hz square wave generator driving a LED driver. Try a CD4047 astable with a drive transistor. https://www.fairchildsemi.com/datasheets/CD/CD4047BC.pdf
  9. ramussons

    Static inverter design

    This is wrt to the 120 degree conduction angle ..... The rms factor of this wave will be (120/180)^0.5 = 0.8 app and this means that the number of windings in the output side of the transformer will need to be 1.25 times the voltage ratio. You will need to use filters at the output to...
  10. ramussons

    Audio/Video to RF. Help!!

    PAL or NTSC video is in the Composite Baseband. Sync, Colourburst .... the works. It's the audio that needs to be FM'ed to 4.5 or 5.5 MHz based on NTSC or PAL. This is the part that needs some care. Invert any composite video and AM it around 52 MHz and you can get it on Ch2 of a TV.
  11. ramussons

    Audio/Video to RF. Help!!

    Does this help? http://www.circuitstoday.com/tv-transmitter-circuit
  12. ramussons

    charging systems question

    Your question should have come with the diagram.
  13. ramussons

    Static inverter design

    The 120 degree conduction is for a Quasi Sinewave invertor. Yes, it will have an effect on the output. Use the RMS values for Turns Ratio of the transformer. But you will need to filter out the Harmonics and the filters will be quite hefty since the switching frequency is 50 Hz. It's better to...
  14. ramussons

    Static inverter design

    Could you please explain the Red part? Why generate 28 VAC and then step it up to 115 V? If you need 115 VAC and 28 VAC, both 3 Phase, the Invertor Transformer will have to be wound that way.
  15. ramussons

    AV audio video red yellow white application

    Yes. So offset a DC 0f .5 Volts and Ensure p-p < 1.0 volt. Technically possible to transport Audio, but ...
  16. ramussons

    AV audio video red yellow white application

    Technically speaking, you have a bandwidth of 3.8 / 4.43 MHz available which can be used for an analog signal ....... :rolleyes:
  17. ramussons

    RCA to HDMI

    Google is your best friend here .......
  18. ramussons

    AV audio video red yellow white application

    I go with davenn
  19. ramussons

    RCA to HDMI

    No Go.:( RCA Audio is Analog; HDMI is Digital. The 2 are not compatible; therefore an Adapter is a must.
  20. ramussons

    Pulse transformer

    I think if you try to reduce the kickback voltage in a pulse transformer setup, you will distort the pulse waveform. If that does'nt matter, a capacitor in place of the diode should also work - provided you take care to of resonant frequencies.
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