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  1. hevans1944

    Signal generator to drive Ultrasonic transducer

    I think what @73's de Edd means is the silicon-steel I-E core of the Bogen brand transformer is not suitable for the kilohertz frequencies that you need. Perhaps you should invest in an inexpensive digital storage oscilloscope (simple single-board kits are available for around $20 if you want to...
  2. hevans1944

    OLD Tektronix Oscilloscope Identification

    It belongs in a museum, not on your workbench. If you cannot sell it, it might be a treasure box of electronics parts. CRTs (cathode-ray tubes) are rare nowadays, so maybe you could build a replica of an early video game based on that. If you NEED an oscilloscope, the very portable (and...
  3. hevans1944

    Not Understanding Arduino useage versus traditional Electronics useage in Devices.

    I guess I will jump in with my two cents worth of comment. Take it for whatever you think it is worth. First, let me say that I just "celebrated" my 81st birthday in June of this year. Perhaps, like @Minder, I started out my electronics career by, at first, simply "playing" with vacuum tube...
  4. hevans1944

    Strange old capacitor

    No, you need three capacitors with a common connection on one end of each capacitor. The other lead of each capacitor replaces each of the three leads on the original capacitor. I would suggest using three polarized, axial-lead, electrolytic capacitors. One of these (16 uF @ 50 wvdc) will be...
  5. hevans1944

    motor advice

    Let's see if I understand the problem... you have two bicycle chains that you have joined to make one longer chain. The chain somehow is attached to something that weighs about a pound or so. The chain is used to move the attached figures (small "dolls" representing people) around the diorama...
  6. hevans1944

    High current, 40 A to 100 A, current limiting devices other than a resistor

    I think @Harald Kapp in his post #3 mentioned electronic current limiting with either bipolar junction transistors (BJTs) or MOSFETs. This is the ideal, minimal to no power lost, way to go: use a variable duty cycle, with current sensing, to control a pulse-width modulated power source. Start...
  7. hevans1944

    Signal generator to drive Ultrasonic transducer

    You should also consider the acoustic coupling between your "loudspeaker" at ultrasonic frequencies and the liquid in which you are trying to create bubbles. It sounds to me (no pun intended) that you are generating ultrasound in air and trying to couple that energy through a metal container's...
  8. hevans1944

    Sign out, log out, ending my session?

    Yeah, I had to change my password to get back in, since my previous one was too strong to remember, and right-clicking in the password field did not restore my previously "saved" password. It's looking like, more than ever, that Electronics Point, by any other name, is dead. But I will linger...
  9. hevans1944

    Math Severity as applied to Serious Electronics

    @John R Retired: As a hobbyist, I used to find and repair "vintage" electronics beginning in the 1950s... as in radios and televisions with genuine vacuum tubes instead of impregnable solid-state electronics. I gave that up, shortly before graduating high school in 1963, because no one wanted...
  10. hevans1944

    Math Severity as applied to Serious Electronics

    @John R Retired: I just "celebrated" my 81st birthday on June 25, 2025. I was forced to retire in December 2014 when the company that hired me to maintain and operate their particle accelerator decided they needed the floor space for office cubby-holes. This was after we had completed some very...
  11. hevans1944

    Math Severity as applied to Serious Electronics

    I started out working electronics as a hobby. First thing I learned was Ohm's Law. This did require simple algebra and basic arithmetic skills. Later, with more formal education, I learned trigonometry and plane (Euclidian) geometry. Then there was an hiatus while my brain matured enough to...
  12. hevans1944

    Motor is too fast

    Thanks for providing a list of manufacturers for Universal motors. But do you have a solution to the original problem of the existing string-mower's motor running too fast?
  13. hevans1944

    Motor is too fast

    Wow, @Minder! You really are old if you remember universal-wound AC/DC motors. And, yeah, I remember the "runaway" problem with series field motors. Are these even manufactured anymore? The OP needs to either replace his motor or gear it down. Do you see any other alternatives?
  14. hevans1944

    convert speaker output to microphone input

    Could you clarify what you want to do? At first, I thought you wanted to use a speaker as a microphone (as most intercom systems do), but perhaps you want to take the signal, connected to the speaker from an amplifier, and feed that signal to the microphone input on a board. That might require a...
  15. hevans1944

    Motor is too fast

    Sometimes we just have to accept reality and bite the bullet. As @Minder stated, it is LIKELY that your string-mower has a BLDC (BrushLess Direct Current) motor because the 8000 rpm speed of the motor you have (measured?) cannot be accomplished with a brushed DC motor with a copper commutator...
  16. hevans1944

    Speaker output ohmage without information.

    It is threads like this that drive me to x.com and conversations with Grok 3.0. Grok is NOT to be trusted, but its "answers" always "seem" to be "reasonable." I recommend trying it before posting in this forum.
  17. hevans1944

    Motor is too fast

    Maybe replace the existing motor, too? Can you upload a picture of what you are trying to accomplish or have already accomplished? I can never get a string-mower to work for more than a few minutes before the string jams... yet another reason to hire someone else to take care of the lawn. <sigh>
  18. hevans1944

    Motor is too fast

    I love it when a plan comes together... especially when PATENTS are involved. We hire a lawn boy to mow our yard every week for about fifty bux a pop. We have a nice electric mower, but he brings his gasoline-powered internal-combustion-engine (ICE) mower and gets the job done much faster while...
  19. hevans1944

    Why do some devices turn on with the mains before the "On" button is pressed?

    Anything that responds to a momentary button press needs power to recognize that event. That is the rational for it. My SONY flat-screen TV has NO front-panel controls, and it sometimes behaves in strange ways, because it is an Android device that Sony apparently cannot program properly...
  20. hevans1944

    Component acquisition for hobbyists?

    I have given up navel-gazing for Lent. Quite a sacrifice, too, since I'm not a Catholic. :cool:
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