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  1. hevans1944

    Sensor for solar irradiance

    Thanks for the images. I don't have any recent selfies to share with the forum, but my avatar picture is pretty much still the way I look today... distinguished, somewhat devilishly handsome, and ageing slowly in outward appearance. In other words, not too shabby for a guy approaching his 72nd...
  2. hevans1944

    Simple thing but no idea how.

    Yes it would be, but I did NOT suggest he do that. I just said it was possible. We are considering milliamperes of neon-lamp current passing to earth ground, which is bonded to neutral at the service panel, not a heavy power-consuming load. So if there is no GFI circuit-breaker supplying power...
  3. hevans1944

    Regarding diodes

    I did read it, but after I had already posted. Isn't it wunnerful how great minds think along similar tracks? :D
  4. hevans1944

    Help with passband filter!

    Might be some useful links here. You also need a notch filter ahead of your bandpass filter to suppress power-line interference, assuming you don't operate in a Faraday cage shielded room with DC power. Simplest filter is probably the Salen-Key active filter which you can find more information...
  5. hevans1944

    Help with IR sensor controlled off-delay dimmer.

    Looks "legitimate" to me. If "magic smoke" isn't pouring out of something, then I would consider any circuit "legitimate" whether it worked as intended or not. Your 47,000 μF electrolytic capacitor is gonna stress that 47 Ω resistor when the BC327 comes on, so make sure it can take the heat...
  6. hevans1944

    Need help with SSR Wiring

    I would have drawn this in a different color, but I suppose as long as it isn't drawn in yellow I can live with it. Looks like it will work. Same caveat as @Minder.
  7. hevans1944

    An easy relay question for some of you "more experienced".

    The relay coils draw only as much current as is needed to operate the relay at the rated coil voltage. You can connect this to a 200 A circuit breaker and it would not draw any more current than it would if you connected to a 20 A circuit breaker. Circuit breakers are there to protect the...
  8. hevans1944

    Regarding diodes

    Some folks use this as a method of "reverse polarity" protection. It doesn't matter how you connect the + and - DC supply to the input, the output is always between a positive cathode and and negative anode. Disadvantage is you add two forward-biased diode voltage drops in series with your DC...
  9. hevans1944

    Simple thing but no idea how.

    I have one of these neon-lamp, internally illuminated, switches configured as a SPDT two-way switch to control an upstairs light from a position on the upstairs wall. It's companion, an ordinary SPDT two-way switch without the neon lamp, is mounted on the downstairs wall near the foot of the...
  10. hevans1944

    New Guy Orlando FL

    Welcome to Electronics Point, NavyBEE! You to the right place have come. We be full of ideas here! Is it analog or digital you wish to explore with us? Hop (ex-Air Force cannon cocker)
  11. hevans1944

    HELP WITH UNDERSTAND OF NAND GATE CIRCUIT?

    Well, doh! I like your new circuit. But what about the wasted power from leaving the LED on when the door is closed instead of pulsing the LED at faster than the decay rate of human persistence of vision? Hah! Bet you never considered that! :p Hmmm. Your circuit does have the advantage over a...
  12. hevans1944

    Linear and non linear system

    You might want to learn it so you can talk to Chinese business people. In case you didn't notice, China is becoming a rather large trading partner with just about everyone in the world. Might help you financially to speak and read at least one dialect of Chinese. But maybe you can just sit in...
  13. hevans1944

    Does electron die?

    Electrons surround every atom in everything. The electrons in your feet (or shoes) support you because they are repelled by electrons on the ground beneath your feet. We live on a sea of electrons that shield the positive nucleus of every atom. You can blame Ben Franklin, an American statesman...
  14. hevans1944

    Linear and non linear system

    It appears, at least to me, that you do not yet have the necessary math skills to analyze or understand control systems. A prerequisite to the study of linear control systems is the ability to set up and solve a system of linear differential equations that describe the control system. For simple...
  15. hevans1944

    HELP WITH UNDERSTAND OF NAND GATE CIRCUIT?

    @dorke You have changed the original functionality! Originally, the LED flashes at a high enough rate that the eye perceives it as being continuously "ON" when the door is closed, because the magnet in the door is using the Hall Effect device to disable the slow first oscillator. This action...
  16. hevans1944

    Linear and non linear system

    More particularly, if a control system can be modeled or described by linear differential equations it is linear. Every other control system is non-linear. All real (stuff you can actually build) control systems are non-linear but are often approximated as linear over some operating range so...
  17. hevans1944

    How to read and solve passage?

    Or if you are like me, it may never happen. If you can borrow a language course on compact disk, such as Rosetta Stone (expensive!), and immerse yourself in it... carry it around in a portable CD player and listen every chance you get... it might help.
  18. hevans1944

    HELP WITH UNDERSTAND OF NAND GATE CIRCUIT?

    You can also find this circuit. and an explanation of how it works here. It is touted as an electronic "door open" indicator, with LED1 flashing continuously at a high frequency as @duke37 explained, when the door is closed and the Hall sensor output is low, disabling oscillator 1 in @dorke's...
  19. hevans1944

    What do people stick their self-adhesive breadboards to?

    I leave the slick cover in place over the double-sided sticky tape, use it, then put it away like Dave. I did have a cheap commercial version with a built-in 5 VDC logic supply, some switches, an oscillator, etc. like Dave showed in his picture, but I left it at work when I retired because it...
  20. hevans1944

    Sensor for solar irradiance

    Serendipity is responsible for a lot of wonderful things if we can recognize when it occurs. You serendipitously chose the right op-amp right out of the starting gate! If I were a betting man, I would bet you are going to be great mechanical engineer! Especially if you integrate electronics into...
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