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  1. BobK

    How do I store energy

    Cool! or Hot! take you pick. :) Bob
  2. BobK

    How can I build a simple sound system for my laptop?

    I can guarantee you that if you put 150W into those speakers, they will be torn to shreds. The 100W (music power) is a bogus rating used to make cheap equipment look good. I maintain my position that 15W per channel would be about right. If the system is drawing 155W, and a typical AB...
  3. BobK

    I need to locate a millisecond delay timer / multi circuit /relay

    Sorry, I didn't notice India. Do a search for "sequential timer", that is how I found that one and I am sure there must be others. bob
  4. BobK

    I need to locate a millisecond delay timer / multi circuit /relay

    Here you go: 1/100th second resolution. http://www.processcontrols.co/digital-timers.html#sequential-timers No price though, you have to enquire, which means it isn't going to be cheap. Bob
  5. BobK

    How do I store energy

    Or, to get more creative, Lift some large weights. Pump water up hill. Spin up a large flywheel. Charge a huge bank of capacitors. But my favorite is compressing air: http://spectrum.ieee.org/energywise/energy/the-smarter-grid/compressed-air-energy-storage-makes-a-comeback Bob
  6. BobK

    Batteries in parallel for higher mAh

    It does if you then reduce the voltage via a DC to DC converter. Say you put 3 nominally 3.7V LiIon batteries with 1000mAH capacity in series. If you then run them through a buck converter and get 3.7V at 1000mA, the batteries will last 3 hours because they will only be draining (at a rate of...
  7. BobK

    Batteries in parallel for higher mAh

    If you really need to add the capacity of these two batteries together, you would need to put them in series and then use a DC to DC converter to bring the voltage down the desired level. Bob
  8. BobK

    Sine Wave from Square wave

    With a switch? Why don't you tell us what you are trying to do. Bob
  9. BobK

    Building a simple radio scanner

    Not to mention that even if you were able to build one, it could never match the performance of a commercially built one nor the price. Bob
  10. BobK

    How can I build a simple sound system for my laptop?

    I don't think those speakers are up for 700W! Something like this should be more than sufficient: http://www.ebay.com/itm/Amplifier-Board-Module-12V-2x15W-Mini-TA2024-HIFI-Digital-Audio-AMP-/271463838799?pt=US_Amplifier_Parts_Components&hash=item3f3481744f Bob
  11. BobK

    Voltage help

    If it has to fit in a compact space why are you using a 12V battery? It will take more space than a 3V battery with the same current capacity. Is there something else that needs to run off 12V? If so, how much current? Bob
  12. BobK

    Sine Wave from Square wave

    If you need only a fixed frequency, why not make an oscillator that produces a sine wave instead? It is easier to convert a sine to a square wave than what you are trying to do. Bob
  13. BobK

    Placement of batteries (button cells) in the same plane on two sides of PCB

    The question I would ask is why you need 4 batteries? Bob
  14. Build a device from a Schematic (Production PC board)

    Build a device from a Schematic (Production PC board)

    I will be creating a production quality PC board the LED flasher circuit in Steve's thread. https://www.electronicspoint.com/threads/building-a-device-from-a-schematic-yet-another-work-in-progress.256843/ This thread will track my progress. I intend to use the BatchPCB service started by...
  15. BobK

    Build a device from a Schematic (Production PC board)

    BobK submitted a new Showcase Item: Build a device from a Schematic (Production PC board) Read more about this showcase item here...
  16. Build a device from a schematic (DIY PC board)

    Build a device from a schematic (DIY PC board)

    I will be creating the production PC Board for Steve's thread: https://www.electronicspoint.com/threads/building-a-device-from-a-schematic-yet-another-work-in-progress.256843/ I thought while I was at it, why not do a DIY one as well? So here goes. I will use ExpressPCB's free software to...
  17. BobK

    Build a device from a schematic (DIY PC board)

    BobK submitted a new Showcase Item: Build a device from a schematic (DIY PC board) Read more about this showcase item here... Bob
  18. BobK

    Transformers and Dimmers

    Or dim them with a low voltage PWM dimmer designed for that purpose. For example: http://www.ebay.com/itm/Brightness-PWM-Switch-Controller-Dimmer-for-LED-Strip-Light-12-V-to-24V-8A-/221490099865?pt=US_Lighting_Parts_and_Accessories&hash=item3391d6b699 Bob
  19. BobK

    Graphical LCDs: alternatives and drivers

    I am not sure if this applies to the graphics LCD that you are using, but the LCD voltage on text LCDs is normally supplied through a 10K pot which is the contrast control, so very little current, and it might need to be adjustable. Edit: Oh, and read the datasheet carefully about that. It is...
  20. BobK

    Switch Project Help

    Or a latching pushbutton DPDT switch. Bob
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