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  1. hevans1944

    Internet schematic OK

    Thanks, @73's de Edd. Looks like it might have a chance of working... how do you find this stuff, and so quickly too?
  2. hevans1944

    Reducing music in videos

    Subtitles work for me, too, most of the time. Listening through a pair of earphones also seems to help. There is a lot of "magic" that can be done with digital audio post-processing, and some of it is available online for consumers to play with. I am absopositively sure the NSA uses the latest...
  3. hevans1944

    Internet schematic OK

    It helps when discussing circuit schematics to have ALL the components labeled. For example, R1, R2, ... Q1, Q2, ... D1, D2, ... etc. like that. Your hand-drawn circuit with the 1N4148 diode, 1 kΩ resistor, and unidentified NPN transistor doesn't look right. What is this part of the circuit...
  4. hevans1944

    What to Do With a Lot of Salvaged Speakers?

    Playing with inexpensive or salvaged speakers is an interesting side hobby to electronics. Most of us have succumbed to that particular bug early in our careers. I can recall articles in Popular Electronics around 1961 on "Sweet Sixteen" loudspeaker arrays (4x4 arrays of cheap 5" speakers) that...
  5. hevans1944

    Philips Oscilloscope Type PM 3206. Service Manual

    Well, what happened when I waited long enough, was TWO copies of the manual appeared on my screen, both seemingly identical although I didn't compare them page for page. For a hobbyist, this was a 'scope to drool over in the 1960s. 15 MHz vertical bandwidth, triggered linear time base, dual...
  6. hevans1944

    Pcb not working?

    Back in the day, we routinely repaired damaged circuit board traces with insulated, solid, 30 AWG wire-wrap wire. Short breaks could be repaired with uninsulated lengths of stripped wire, and longer breaks (like an entire track vaporized!) could require 24 AWG solid wire and also a spot or two...
  7. hevans1944

    Tek 475 scope

    @Corri" Yar, 86 sorta gets you in the ball park of old folks, at least down here in southwestern Florida where anyone less than eighty is considered to be a youngster. I'm not there yet at 73 going on 74 in June, but I do aspire to becoming old. It looks like you are "beating the odds" with...
  8. hevans1944

    Solenoid Piston help

    In most engineering fields the KISS principle is applied. In your animation, the piston head, attached to the solenoid coil, compresses air in a cylinder while allowing the air to escape through the small red orifice. There is no indication that any sort of valving is applied at any time. So, on...
  9. hevans1944

    Tek 475 scope

    The manual at the link @dorke provided is free from Tektronix. I downloaded it and didn't see any markups. There are still a few (old) people around who make it a hobby, of sorts, to repair "vintage" Tektronix oscilloscopes. The problem is finding them, and finding one willing to have a go at...
  10. hevans1944

    Solenoid Piston help

    Okay, not much we can offer you since you seem convinced that the moving coil (solenoid) is the best and/or only solution to your problem. Your construction is reminiscent of a loudspeaker whose voice-coil (your solenoid) is suspended in a magnetic field (your neodymium magnets) by a flexible...
  11. hevans1944

    Solenoid Piston help

    Is it your intention that the solenoid (with wires attached) be the moving piston? This is not a good idea because, if the piston must cycle numerous times, the wires will eventually break from fatigue stress. A better solution might be to use the neodymium magnets (perhaps super-glued...
  12. hevans1944

    Device to measure total run time of an electronic instrument

    Yes, you could very well be in the wrong place. Electronics Point is a community for members to discuss, advise and debate electronics related topics. It is also mainly a do-it-yourself (DIY) hobbyist forum... not a solution search-engine set up for the convenience of drive-by problem posters...
  13. hevans1944

    Current measurement issues

    Haven't started a MOT project yet, but I did check the garage awhile ago to make sure the microwave oven was still there. It is a really nice 1200 watt General Electric branded oven that is poorly made. There are several interlock switches that have to be either closed or opened before the...
  14. hevans1944

    Hello, can somebody help me with an240P

    Get a working FM radio and a set of schematic diagrams for that radio. Get an oscilloscope with at least 50 MHz bandwidth. Get an RF signal generator with FM capability. Get and read several different text books, by different authors, on how radios work. Put all this together on a well-lighted...
  15. hevans1944

    Current measurement issues

    Sure you can. Just get two (or more) lengths of heavy-gauge wire, maybe a foot or so long and clamp the ends together on each end. If the wire happens to be insulated, strip off about an inch of insulation on each end before inserting the wire into the pressure clamp. Now separate out one of the...
  16. hevans1944

    Current measurement issues

    Doh! You think? Looking at the PDF file you included, I noticed that the no-load primary current is 5.5 A, about half the full-load primary current of 10.6 A. That's terrible! Looks like you didn't use enough steel in the transformer core, or not enough turns of wire on the primary, or both...
  17. hevans1944

    What transmitter receiver setup is best for me, and how do i set them up?

    The ten (or more) accelerometers are analog devices. You will need to digitize (at least) thirty analog signals and then send this digitized data to your serial-to-USB interface, presumably using some sort of wireless data link such as Bluetooth or XBee. That's not the hard part. The hard part...
  18. hevans1944

    12v 5A to 12v 10A

    Thank you, @Harald Kapp, for the link to an excellent resource on current sharing among multiple power supplies. Unfortunately, based on the OP's misconception that a 12V 5A power supply can somehow be magically "converted" to a 12V 10A power supply with just a few additional components, the...
  19. hevans1944

    You know you're a valued customer when...

    You know you are "a valued customer" when you receive unsolicited free samples. It's been YEARS (decades even) since I've received any free samples. You used to be able to request free samples on the Texas Instruments website, but it's been awhile since I tried doing that... never hurts to ask...
  20. hevans1944

    Omnidirectional Ultrasonic transmitter

    Are we still wasting time playing "guessing games" on this thread, which is going nowhere? I thought this was a discussion forum, yet the OP deigns to not discuss WTF he is trying to do, offering only that a small handheld 40 kHz omnidirectional ultrasonic transmitter is somehow required to do it.
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