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  1. BobK

    Creating a different kind of hearing aid for my dad.

    This is an interesting idea. I could not find any thing using bluetooth, but I found receivers that can handle multiple microphones that are made for stage performers. Like this: http://www.zzounds.com/item--SHUPG14PG185 If I am reading it correctly, the receiver can handle up to 8...
  2. BobK

    Digital Pot setup

    You will need a supply of at least 12V for the opamp. And you need one that can include ground in the input and output, an LM358 would work fine. Bob
  3. BobK

    Running an LED off a 120v wall outlet

    Just looking at some micrscopes for sale. The better ones seem to have something like a 20W halgen bulb. Looking these up I got 350 lumens. You are going to need about a 3W to 5W LED. These take 1A or more of current at about 3.6V. And they need heat sinking. Bob
  4. BobK

    Digital Pot setup

    You won't get 0-10V out of the micro. But an op amp could multiply it by 2 to put it back in the range you need. Bob
  5. BobK

    Running an LED off a 120v wall outlet

    What was the original light, that would give us some idea of what you would need to replace it? A typical indicator LED running at 20ma puts out less than a lumen. I have some white high brightness LEDS that put out 8 lumens at 30ma. I use one for a book (actually kindle) light, and it is...
  6. BobK

    Running an LED off a 120v wall outlet

    Doesn't everyone have an entire bin full of old wall warts? It's one of the few things I guard againt my anti-pack-rat wife! Bob
  7. BobK

    Running an LED off a 120v wall outlet

    Here. Bob
  8. BobK

    Newby Electronics Question....

    Oh, and by the way, that circuit produces a nice sine, i'm sorry, gravity wave in simulation: Bob
  9. BobK

    Newby Electronics Question....

    I don't see any 10G resistor in the circuit you pointed to. Is that your own innovation? Bob
  10. BobK

    Cheap Lithium Ion Chargers - Safe?

    If you really want to know, put an ammeter in the circuit. Bob
  11. BobK

    Square wave input, PWM output?

    This is contradictory. An input cannot be a DC voltage AND a square wave. Bob
  12. BobK

    Running an LED off a 120v wall outlet

    Uh, no. He is talking about a high-power LED. These typically start at 350ma and go up from there. A 9V cannot operate it for 2 hours. In fact, even at 5ma, a 9V battery could operator for only a few days. Bob
  13. BobK

    Voltage Regulators

    Well, a linear regulator that takes in 2V and puts out 5V would be quite an accomplishment! You need a DC-DC converter. You can find very cheap units on EBay. Bob
  14. BobK

    Cheap Lithium Ion Chargers - Safe?

    Lithium batteries are actually one of the easier kinds to charge. You use a constant current unit it reaches some voltage then swich to constant voltage until the current drops to zero. This could be enough circuitry to do that. Bob
  15. BobK

    Electronics Question About Advice

    Perhaps you should read a real electronics text book. It does not sound like what you have read gave you any foundation at all. Bob
  16. BobK

    Running an LED off a 120v wall outlet

    You start with a wall wart that lowers the voltage to something like 5V, then read this: https://www.electronicspoint.com/got-question-driving-leds-another-work-progress-t228474.html Bob
  17. BobK

    Looking for somebody to create my project

    Okay, here is my analysis of what you would need: A single 1.5V battery cannot light an LED, you would need a boost converter or you would need to use 2 cells. A single 3V lithium battery might be a better solution, but the common ones are over 1/2 in in diameter which, I think, is bigger...
  18. BobK

    Help in desiging an electric motor!

    I don't think that kind of question can be answered in general, else all motors would be the same kind, wouldn't they? Bob
  19. BobK

    Crashing after 145 seconds

    This is a matter of semantics. Since I have been working on compilers professionally for over 40 years, I may use a different language than you do. To me, the compiler is only that piece of code that translates source code to object code. It does not include the library functions that might...
  20. BobK

    Charging a Tablet off of Car Battery

    The amps do not matter, as long as a source can provide >1.5A at 12V it can charge your laptop. The only problem with conecting it directly is that, when the car is running, the voltage of a car's electrical system is more like 14+ V. I don't know if this would damage the laptop or not...
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