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  1. hevans1944

    5v regulator with lm350 with 9v input

    Being an amateur does not mean you have to remain ignorant. Read the datasheet. Try to understand what it says. Look at the example circuits the datasheet recommends. Then come back here to ask questions. If you are here to learn, we will try to teach you. If you are here looking for someone to...
  2. hevans1944

    Need a little help on circuit for 120VAC to 12VDC

    Seems this part originated in Asia, possibly Taiwan. Good luck finding a distributor. I did find a datasheet.
  3. hevans1944

    Need a little help on circuit for 120VAC to 12VDC

    When I started out, about 1950 or so, I had to beg money from my mom or my grandmother for dry cell batteries to do simple electrical experiments. There was little opportunity for a six year old child to earn money by working. But I soon "graduated" to building power supplies from salvaged...
  4. hevans1944

    5v regulator with lm350 with 9v input

    Did you download and read the datasheet for the LM350?
  5. hevans1944

    Need a little help on circuit for 120VAC to 12VDC

    Beginners are well advised to purchase a COTS (Commercial Off-The-Shelf) bench power supply with voltage and current controls and meters for both. The last thing you need when learning electronics is an unreliable power supply for your experiments. If you want to do any analog work, purchase a...
  6. hevans1944

    Continuity testing wire capacitance

    Well, I don't. But the link I provided has advertisements for several hand-held models you could maybe fit in your Back pocket. As @Tha fios agaibh implied, TDRs are commonly used to test the integrity of fiber-optic links. The last time I needed a TDR was to measure the length of a spool of...
  7. hevans1944

    Continuity testing wire capacitance

    The easiest way to determine cable length is with a time domain reflectometer (TDR).
  8. hevans1944

    MSGEQ7 analog circuit?

    You want to use a 3-bit Johnson counter, the CD4022B, rather than the CD4017B, which is a decade (4-bit) counter. Since the counter outputs are already decoded, you just need to connect each decoded counter output to one analog switch control input so that switch turns on and charges a...
  9. hevans1944

    MSGEQ7 analog circuit?

    @(*steve*), if I understand this doobie correctly, it is a bunch of analog bandpass filters whose outputs drive peak detectors that are read in sequence with the analog multiplexor. Apparently the act of reading the mux also causes a 10% decay in the peak-detector output for that channel. To...
  10. hevans1944

    Audio/Video to RF. Help!!

    I suppose if you have a lot of discrete NPN and PNP small signal transistors on hand, salvaged from discarded radios and TVs and other electronic stuff, you might be able to construct the circuitry used in the MC1374P, which is conveniently published in the datasheet without component values of...
  11. hevans1944

    Audio/Video to RF. Help!!

    Which is why I originally opined that it wasn't simple. However, the audio is FM modulated on a sub-carrier that is (for NTSC) 4.5 MHz higher in frequency than the AM modulated video carrier. Apparently the "simple" circuits work because the FM discriminators in old TVs don't care where the FM...
  12. hevans1944

    potential health hazard from electronics

    Sure, I started playing around with molten lead and solder about sixty-something years ago while living with my grandparents. Grandfather had a gasoline blow-torch that he used to melt lead to cast fishing lures in a home-made aluminum cavity mold. After the cast lures cooled, he tied bits of...
  13. hevans1944

    charging systems question

    @Colin Mitchell that was incredibly helpful! I really liked the disappearing components explanation that removed the clutter and simplified the schematic. Ahem, did you forget to take your crotchety pills today?
  14. hevans1944

    Audio/Video to RF. Help!!

    The audio front-end seems to be needlessly complicated, up to and including the transformer T1. And I see nothing that precludes providing video with either PAL or NTSC formatting. This is a simple RF oscillator with amplitude modulation injected in the emitter circuit and audio phase modulation...
  15. hevans1944

    Audio/Video to RF. Help!!

    This page under the heading "ATV RECEIVERS/TRANSMITTERS/DEMODULATORS" has many circuits, but unfortunately most are just schematics with few details on actual construction. They all seem to be based on a simple RF oscillator that is amplitude modulated by the composite video signal and...
  16. hevans1944

    Audio/Video to RF. Help!!

    Just sayin'... if you can get 'em it's the way to go. Or visit this amazing web site which has a link to your circuit and a few dozen others. Iulian Rosu has done an amazing job of compiling references to just about anything electronic for the experimenter and radio amateur..
  17. hevans1944

    Audio/Video to RF. Help!!

    I am afraid there is no "simple circuit" to do this. You must take composite video, which includes sync and presumably the color burst signal on the "back porch" of the horizontal sync pulse and apply it as partially suppressed carrier with vestigial sideband modulation on a CH 3 or CH 4 video...
  18. hevans1944

    One Way Communication from Chip-to-Chip

    Sometimes an employer will assign a "simple" task to a new hire, just to see what he is capable of doing on his own. Perhaps this ancient μP is part of a product, and they just want @Pradip Nepali to become familiar with its operation. Sort of a sink-or-swim situation. Who knows? But the nature...
  19. hevans1944

    Changing Signal Frequency And Frequency Overtones Respectively

    Well, I will sleep on this and maybe some inspiration will occur... Music is mathematically challenging. But from where I am looking at it now, the approach mentioned by @duke37 appears to be the only viable approach... and it will be extremely complicated to "sort out" the Fourier spectrum...
  20. hevans1944

    One Way Communication from Chip-to-Chip

    (Gryd... it is. But the microcontroller in question is an obsolete Atmel AT89C51, not recommended for new designs, that happens to have serial transmit and receive ports. It may even have a built-in UART, although that could also be implemented easily enough in firmware.)
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