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  1. hevans1944

    Missing resistor in a voltage divider network

    The Bits and Parts website has a link to the LM3916 datasheet which contains a wealth of information on how to create VU and PPM (Peak Program Meter) digital bar-graph displays using the LM3916, and how to extend the input range by cascading it with the LM3915. Anyone who wants to do as I...
  2. hevans1944

    Missing resistor in a voltage divider network

    I would imagine that TI or National Semiconductor made a boatload of all three IC types back around the turn of the century. Now the 3915 and 3916 are still widely available here in the States from Internet sellers, such as eBay, but no more are being made to the best of my knowledge. Perhaps...
  3. hevans1944

    Missing resistor in a voltage divider network

    Thanks for the link! I thought this part was obsolete, but it appears to be going strong and is recommended for new designs by Texas Instruments. The TI datasheet is comprehensive and even has a simplified schematic diagram of the flash analog-to-digital converter used in the LM3914. Are the...
  4. hevans1944

    Missing resistor in a voltage divider network

    I do know this, having played with flash A-to-D converters in the 1970s. I doubt you are "potentially in the mire" because you have the ability to discover how it was done, lo! those many moons ago. And that is why no one that I know actually builds flash converters from discrete components...
  5. hevans1944

    Coronavirus transmission prevention device.

    And yet you dare point to a link that you think addresses your ill-defined problem? Diode theory? How about some common sense first? If your contraption "goes off" every time the wearer moves a fork or a spoon towards their mouth, how do you propose to handle that? Turn it off while eating...
  6. hevans1944

    Missing resistor in a voltage divider network

    Now, where is the rest of the circuit that accepts the op-amp outputs and somehow causes the 7-segment display to show the digits 0, 1, 2, 3, 4, or 5 depending on how many op-amp outputs are "high"?
  7. hevans1944

    Coronavirus transmission prevention device.

    From the above comments, it appears that I may have infected @Martaine2005 and @Alec_t with my not-so-subtle-sometimes wit. Don't worry, it's not fatal as long as there is no personal face-to-face contact, but like the herpes virus it stays with you for life.:D @TDAKS has put forth an excellent...
  8. hevans1944

    12v 0.5A auto trickle charger

    I have lost track of the number of hours I have wasted over the years trying to revive dead, or almost dead, sealed lead-acid (SLA) batteries, discarded by the end-user and then "salvaged" by me from emergency lighting fixtures and small non-interruptable power supplies. Salvage means the object...
  9. hevans1944

    Creating a user interface for arduino.

    Explicit and immediate de-bouncing of a switch contact is sometimes unnecessary if all you are looking for is a change of state before initiating some further action. This often occurs while the program is in a "wait loop" that periodically examines a port bit for a change of state. For...
  10. hevans1944

    Regulator to limit 12v DC current

    "Electrolysis of water" discussions do indeed often lead into woo-woo "science" that is not tolerated here. What TO DO with colloidal silver produced by electrolysis of water will 99 44/100% (the "purity" of Ivory-brand soap) of the time lead directly into a woo-woo discussion. That is why the...
  11. hevans1944

    I am building an electric fence driver and need to know if has too much or too little power

    Your electric fence definitely needs to be pulsed with a sufficient interval between pulses to allow whatever is being shocked to disengage from the fence. If excited continuously, lethal results could occur. Only Government entities are allowed to use lethal force in this manner.
  12. hevans1944

    Reducing battery charger output

    Yes, a properly sized lamp will do the job, but the voltage drop across the lamp will decrease as the battery voltage approaches the charger voltage and the lamp resistance will therefore also decrease. You need to make sure that the charger voltage remains low enough to prevent overcharging if...
  13. hevans1944

    Need help building RF Detector

    I wanna bump this thread from 2014 to 2019 with some newer tech that was available then, but may be a lot cheaper now... The more sophisticated "bugs" are silent, not transmitting anything until they receive a coded command sequence. The digital coded command sequence can be almost anything the...
  14. hevans1944

    AC power from solar installation into home wiring?

    Yes, please DO FOLLOW @davenn's advice! Generally, several panels are connected in series and several of those series combinations are connected in parallel to provide sufficient POWER (voltage times amperes) to make it worthwhile to connect the panel outputs to an AC inverter to power home...
  15. hevans1944

    Do USB ports (for charging only) require FCC certification

    Unless, perhaps, it uses a high-frequency switch-mode supply. I don't know if those need FCC approval or not.
  16. hevans1944

    Sciaky model C.R.O.I. what is it?

    My first oscilloscope was an EICO 460K, built from a kit. It had a non-triggered, reoccurring, synchronized sweep like @bertus described in post #4, but with what I thought was a huge 4" CRT. It was pretty good for TV servicing, but I didn't find out until I went to Air Force tech school in 1963...
  17. hevans1944

    Strong slide switch

    See @Fish4Fun post #6 above. Tell us what you are trying to DO and let us make suggestions on how to do it. A Microchip PIC microprocessor can easily be interfaced to a push-button switch to increment a software "counter" that selects one of several PIC outputs. Each output controls at least one...
  18. hevans1944

    Woo-Woo DC circuit for electrolysis

    I don't recall reading about any brain protective benefits, but coconut oil is the ONLY vegetable oil we try to consume. Other oils for food consumption we try to avoid. We buy large "tubs" of coconut oil, which is a solid at normal room temperatures but readily melts at body temperature, and...
  19. hevans1944

    Need help with Arduino Code for coil winder

    I remember that. What apparently was illegal was FTDI rewrote their driver to detect and then deliberately brick foreign RS-232 to USB adapters. Not nice to deliver malware that bricks your competitors products, but where would the Federation of Planets be if just anyone could make di-lithium...
  20. hevans1944

    Need help with Arduino Code for coil winder

    Yikes! I have a couple of Ardunios with Bluetooth shields that I haven't "played" with in years, having been sidetracked to Microchip PICs by @KrisBlueNZ shortly before he died. What! You thought I was short with @Arun@arduino? @twister thinks I am mean, but what do I care what a 72 year old...
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