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  1. BobK

    Running a PWM controlled Motor off a Step Up Converter

    Easier would be to provide a 12V supply and use the 7.4V PWM signal to control the 12V power to the load. All that is needed is a MOSFET. Bob
  2. BobK

    (woo woo) Resonance follower and adapter

    Yes, I can suggest that you stop spending your time and money on something that provably cannot work. Bob
  3. BobK

    How do i power this laser

    I think maybe you missed the lame joke. Think battery sizes. Bob
  4. BobK

    How do i power this laser

    Or a 2032 for twice the capacity! Bob
  5. BobK

    Running a PWM controlled Motor off a Step Up Converter

    If PWM was used, that would indicate that the starter motor was designed to run off less than 12V. Did you try running it at full duty cycle (or just skipping the PWM) from the 7.4V battery? Bob
  6. BobK

    Does this have a balancing board

    You can probably tell by how many connections it makes to the battery. To do cell balancing, it would have to connect between each pair of cells in series. Bob
  7. BobK

    555 in astable mode

    To get an accurate and stable 56KHz, your best bet is to use a crystal oscillator + divider. A 555 will drift with temperature and aging of components. Bob
  8. BobK

    Voltage regulator for power supply

    Are you sure the coupling constants you have specified in the simulation are correct? If they are not, it does not represent reality and if they are quite a bit lower in reality, I would expect it to perform as you said it does. Bob
  9. BobK

    OptiSound 5

    Wow. That is some frequency range for a subwoofer:
  10. BobK

    transistor pairing? or not?

    I call, and raise you West Coast Swing. (Though, I am definitely bluffing on Samba and Paso Doble, and my Jive might look a lot like East Coast Swing..) Bob
  11. BobK

    240W power adapter can cause problems for a laptop designed for 180W?

    Did you try going back to the original adapter? If so, does the problem persist? Bob
  12. BobK

    Negative Spike Voltage

    Really? I thought the research indicated that sudden acceleration was generally caused by a driver hitting the accelerator when they thought they were hitting the brake. Can you link to anything that says it is negative voltage spikes? Bob
  13. BobK

    transistor pairing? or not?

    Because nobody can tell the difference between 0.1% and 0.01% distortion. Not to mention the fact that no speaker get much better than 1%. Are you an audiophile, Dorke? Bob
  14. BobK

    Picaxe programming help

    It will also help to put the LDR at the end of a cardboard tube to screen out light other that that of the laser. Bob
  15. BobK

    [HELP] Trying to build very specific portable battery!

    Here is a battery that might be suitable. Only 6 pounds. Only $260. http://www.batteryspace.com/lifepo4-battery-12v-25ah-300wh-50a-rate-with-led-indicator---replace-sla-12v-20ah-lighter-weight-and-higher-capacity----un38-3-passed.aspx Bob
  16. BobK

    [HELP] Trying to build very specific portable battery!

    To answer your question. A 120W appliance operated for 1 hour need 120 Watt Hours. From a 12V battery this is equivalent to 10 Amp Hours. But, 1. Efficiency will likely be about 80%, so 10 / 0.8 = 12.5AH. 2. Batteries of this size are rated when discharged over 20 hours. At higher...
  17. BobK

    Power bank plugged on charger all the time

    50,000 mA Hours, I doubt it. Does it charge your phone 25 times on one charge? Bob
  18. BobK

    transistor pairing? or not?

    On the other hand, 1% is easy to achieve and, in listening tests, almost no one can hear 1% distortion. Amps that achieve distortion levels like 0.01% are a scam. Bob
  19. BobK

    Step Up Converter?

    Yep. Which means if you step up from 12V to 24V and you need 20A at 24V, you would need 40A from the 12V supply + some for inefficiency. Bob
  20. BobK

    transistor pairing? or not?

    Yes it can. The feedback makes it essentially an op amp, with the output voltage being a ratio to the input voltage. There will still be distortion, and the intermediate signals could be quite distorted, but the output should follow the input quite well, even though the driving signals for the...
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