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  1. hevans1944

    Help Identifying a Battery

    This has to be one of the worst kludges I have seen in more than sixty years, including some kludges made by yours truly. So, instead of electrifying the two brass rails and incorporating sophisticated remote control electronics to operate the engine, we have a pair of 1.2 V Ni-MH cells powering...
  2. hevans1944

    Help identifying a resistor

    This is an inexpensive meter based on a widely available integrated circuit. As long as it is assembled properly it is a fine meter for hobbyist use. The maximum resistance range is 2000 kΩ or 2 megohms, well within the range of a 1.5 MΩ resistor. You should test the meter to make sure it...
  3. hevans1944

    Help Identifying a Battery

    They should be rechargeable, but you never know when purchasing from Asian merchants on eBay. There is a lot of inoperable junk being sold on eBay. Are these 1/3AAA cells? Button, flat-head, or solder tab type? Are you sure you have them connected with the proper polarity? Did you solder...
  4. hevans1944

    Help Identifying a Battery

    Using the picture above as a guide, use a single-edged razor blade to make an incision along the length of the two cells. Make another incision around the circumference between the two black lines that are closest together. This will separate the two cells and you can peel the shrink-wrap...
  5. hevans1944

    Newb wanting to BT my van

    Okay, I apologize to @KeithM for the way I responded to his post. Let's get back on track as he suggested and discuss motors and Bluetooth controllers. Motors first: I have worked on automobiles with power windows. They are a nightmare to get access to the mechanism, which in my experience...
  6. hevans1944

    switching a relay - but on second switch. ( if that makes sense? )

    I am a little confused about how your model will work. Are you going to polish up that old warhorse shown in your picture, apply a fresh coat of green paint, and drive it with an electric motor? Yikes! What a sad ending for such a fine example of 19th Century engineering. Do you own this engine...
  7. hevans1944

    Newb wanting to BT my van

    Problem is, folks often propose things here that are dangerous. We don't aid or abet dangerous projects. The original poster is an admitted "Newb" who teaches English to students in Taiwan. He has been a member of Electronics Point since April 13, 2012 but has posted only four times, including...
  8. hevans1944

    Frankenstein's Components.

    I once did a similar "experiment" by accident while fooling around with my ancient natural gas-fired gravity furnace. Managed to ignite the gas in the air-mixing manifold instead of in the burner. The roar was quite satisfying! But I quickly shut off the gas feed and was afraid to try to...
  9. hevans1944

    Newb wanting to BT my van

    My point exactly. My wife, if riding beside me, won't let me touch the air flow controls or the radio! She actually doesn't like the way I operate the steering wheel, gas pedal, or brake pedal either. I guess it has something to do with my Mario Andretti gene that activates when I get behind the...
  10. hevans1944

    why would parasitic resonance defeat inductance?

    In an inductor or transformer, inductive reactance is usually the only desirable factor and resonance is NOT an objective. Parasitic capacitance is just that: a parasite that prevents desirable operation, getting worse as you approach the resonant frequency, created by the desirable inductive...
  11. hevans1944

    Newb wanting to BT my van

    Fugeddaboutit. Power windows are not compatible with hand-cranked windows. What else are you gonna use the tablet for? Conversations while driving? I have remote controlled outside mirrors on my Ford Taurus station wagon, in convenient reach of the driver without taking my eyes off the road to...
  12. hevans1944

    Microstrip Antennas Manipulation

    Based on your lack of experience, as evidenced by coming to a hobbyist forum where most of the newbies are confounded by the problem of lighting up LED strings, I would have to say your chances are somewhere between slim and none. Do you have access to a gigahertz capable vector network analyzer...
  13. hevans1944

    Two Compressors, One Pump

    If each compressor has a terminal labeled "F" there must also be a common terminal somewhere from which you measure 12 V DC from "F" to that common terminal. Connect the coil of a SPDT relay (the most common kind) that has a 12 V DC coil between "F" and the common terminal on each of the...
  14. hevans1944

    Choosing the right device & circuit to convert DC to AC?

    Yeah, @dorke is on the right track with his questions. Let's cut to the chase: tell us what you are trying to DO and we will offer advice and/or suggestions on HOW to do it. Maybe something like this: So, I found this really neat thermopile that produces at least 10 W of DC power when I place...
  15. hevans1944

    high DC voltage reducer

    A "good" design offers high quality, low price, and quick delivery. Choose two out of three.:D
  16. hevans1944

    Building AC-DC converter

    I agree 100% with this. Newbies need to confine their learning experiences to low voltages, typically produced by batteries or, as you suggested, plugpacks or wall-warts, but even these can be dangerous if not properly constructed. I can appreciate the frustration that @dan tyson must be...
  17. hevans1944

    Impedance

    You are thinking bs. Do as @Minder suggested and learn what resistors, capacitors, and inductors DO and HOW they do it. Some simple algebra and trigonometry will be involved at first, but you can go much deeper down the rabbit hole with a little calculus and a simple differential equation or...
  18. hevans1944

    Building AC-DC converter

    It would be better, for reliability, to build a dc power supply on its own circuit board and connect it to your breadboard with jumper wires. Maybe even put it in a little box with a power cord, fuse, power-on indicator light (or LED), and 5-way binding posts for output connections. What voltage...
  19. hevans1944

    high DC voltage reducer

    Be afraid, be very afraid, of cheap universal USB power supplies assembled in Asia. Some do not adequately isolate the power-line input from the 5 V DC output. This has allegedly led to lethal consequences. See this article for more information. Personally, I would not want to operate anything...
  20. hevans1944

    DC Motor drive

    I remember diacs. Not the most ideal component for symmetrical triggering, plus it depends on an RC network to determine where on the phase it triggers. You could really complicate this and (probably) have a lot of fun doing so: Phase-lock a high-frequency (20 kHz) oscillator to the line...
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