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  1. BobK

    Parallel and series generator and batteries

    If you put the generators in parallel you will not have enough voltage to charge the batteries in series. You cannot charge a 24V battery from 12V. I agree with Steve that each generator should be connected to one of the batteries. However, you are going to need some kind of a power...
  2. BobK

    experiment

    Watts is not a measure of energy, it is a measure of power, which is energy used per unit time. So Watts per hour is a meaningless concept. If it was Joules (a unit of energy) per hour that would correspond to 1 / 3600 Watts since 1 W is 1 Joule per second. In terms of your project. If it...
  3. BobK

    Advice on splitting voices

    It occurs to me that there might even be a third interpretation of what you are trying to do. Maybe you mean that, depending on what frequency your voice is at, it would come out of one of several speakers. For instance, if you sang a song, each note might come out of a different speaker. So...
  4. BobK

    Back up power for small load, extended run time

    Never mind, I had a mind fart. Yes, with a battery providing 420 WH you can draw 50W for about 8 hours. What I meant to say was less that 1/2 of the 20 hours, not 1/2 hour. Bob
  5. BobK

    Advice on splitting voices

    You still have not specified whether you are trying to separate out the multiple frequencies in your voice, or you want to change the frequency of your voice to a different frequency. The methods for doing these two things are entirely different, so we need to know which it is. Also note that...
  6. BobK

    Maplin Electronics in the USA?

    You need a good lawyer, then. A false arrest suit would be a no brainet if what happened is as you say. The government cannot hold people for two months without charges. Bob
  7. BobK

    Maplin Electronics in the USA?

    Sorry, but I think it is you that is paranoid. I have been building electronics projects for 50 years, and not a single visit from the FBI. The reason we don't have electronics retail stores in the U.S. is purely economic. To make money at it the prices have to be 10X to 100X what we can get...
  8. BobK

    Voltage on a white LED.

    10000 lumens at 20mA. That is some efficient LED! Maybe you meant 10000 mcd? Bob
  9. BobK

    Secure Brief Case - Electronically activated lock

    A Windows tablet just to operate the lock mechanism? Sounds like a severe case of overkill. A microcontroller and bluetooth module would be more appropriate. Bob
  10. BobK

    Audio splitter With Amplification

    Yep, I did not consider that. Bob
  11. BobK

    Induce current in air?

    Yes. It is called a spark. Or, on a larger scale, lightning. Bob
  12. BobK

    Back up power for small load, extended run time

    No your math is off by a factor of 10! You calculated how many amps are required at 120V. But the battery (I assume) is 12V. It will require 10 times the required amps from the battery to get the current needed at 120V. The correct way to do the calculation is by using Watt Hours. You...
  13. BobK

    LED burns when oscilloscope is connected to it

    If it has two probes, it can probably show you the difference between the two, which is exactly what you want. Bob
  14. BobK

    Audio splitter With Amplification

    http://www.ebay.com/itm/PAM8403-3W-2-Mini-Digital-Audio-Class-D-Amplifier-Board-USB-DC-5V-Power-Supply-/272315746788?hash=item3f674889e4:g:9U8AAOSw-FZXkDWR Bob
  15. BobK

    Audio splitter With Amplification

    A couple of comments. LM386 is very old technology and not very efficient. There are 3W class D stereo amplifier available on EBay for a couple of bucks. This would be much better for your application. It would last twice as long on batteries, for example. Also, if you are connecting 5...
  16. BobK

    LED burns when oscilloscope is connected to it

    Unless the O-scope has an isolated power supply, you cannot connect the ground lead to anything but ground! Since you are powering the board and the scope from the same PC,they share a common ground. Which means that wherever you connect the ground lead, you have shorted that point to...
  17. BobK

    Parallel LEDs - resistor needed?

    If you are driving them from an LM358 it will be overloaded and unable to source the current the LEDs want. It is a bad idea, but you can probably get away with it if you think they are bright enough. Fortunately, the LM358 is rated for continuous short to ground, so you will not damage it...
  18. BobK

    Advice on splitting voices

    Could you be a little more detailed in what you are trying to do? Do you mean that you want to change the frequency of your voice? Or do you mean that the lower frequencies should come out of one speaker and the higher frequencies out of another? The second is what is called a crossover...
  19. BobK

    Amps measurement of a battery

    More likely just blow a fuse. I know from experience :) Bob
  20. BobK

    Maximum current supply tolerable by 1A Motor driver IC

    Here are some answers: 1. How much current does your magnetic torque rod take? That is what the power supply should provide + a margin of safety. Note that the chip is not limiting the current to 1A, that is what it can handle safely. If the device draws more than 1A at 5V. then you have...
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