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  1. BobK

    24VAC half bridge rectified = xx DC???

    And it is half wave, not half bridge. A half bridge is an entirely different thing. Bob
  2. BobK

    How to connect op amps in parallel

    I have seen capacitors and transformers used for coupling a signal to mains. Bob
  3. BobK

    How to connect op amps in parallel

    To be a little more helpful, lookup summing amplifier. Bob
  4. BobK

    How does a GPS receiver/transmitter (transceiver) work on a circuit board?

    there are 3 main components you would need. 1. A GPS module. Note module, not chip. 2. A GSM module. This is the cellular communication part. It would use a SIM card to connect with a carrier. A SIM card alone does not do anything except identify the subscriber. 3. A microcontroller or...
  5. BobK

    How To Prevent Short Circuit With A Simple Wire From One Outlet Prong To The Other

    In diagram B, one device you can put there to prevent a short is an air gap. Simply seperate the in and out wires by a cm or so and there will be no short circuit. The question is, what do you expect this loop of wire to do? Do you expect current to flow through it? If so, how much? Why so...
  6. BobK

    Vacuum Tubes

    Me too. It would have a warmer, more expansive sound with greater depth and richness. Filaments are not a problem, my iphone is already warm enough to emit electrons when running some apps. Bob
  7. BobK

    New Product Prototype

    Also, the receiver uses 5 to 7mA. A 2500 mAH battery would last 2 weeks. Bob
  8. BobK

    New Product Prototype

    I am missing something here. If you can wire out a charging jack, why not a switch? Bob
  9. BobK

    Vacuum Tubes

    yep,nothing is perfect, but I think the JFET is the closest. Bob
  10. BobK

    Vacuum Tubes

    However, one of them draws a lot of current through the input, operates over a very limited range of input voltages and is far from an ideal transconductance device. Bob
  11. BobK

    Questions.

    1. The microprocessor contains a PLL (phase locked loop) which multiplies the incoming crystal frequency to get it's clock frequency. This is for two reasons, crystals are not common for the GHz frequencies used, so you use a lower frequency and multiply it. Also, you can change the clock...
  12. BobK

    Running LED from USB

    See here: https://www.electronicspoint.com/resources/got-a-question-about-driving-leds.5/ Bob
  13. BobK

    How to change LED flashing?

    The way to change it is to throw away what you have and build a new circuit. Bob
  14. BobK

    Help with DC / DC boost controller chip

    The solar panels cannot produce enough current. How much current does the light require? If the solar panels under load are 0.65V they would have to produce about 8 times that much current to run the light. Bob
  15. BobK

    Wiring LED Lights

    The first problem is that 120VAC peaks at 170V. And you don't want to be running them off the line anyway -- too dangerous. The next problem is that you cannot put flickering LEDs in series. When any one is off, all would be off. You need a low voltage supply, like a 5V USB charger, and...
  16. BobK

    Linux controllable function generator

    Is it okay if I go below budget by about £540? http://www.ebay.co.uk/itm/FY3224S-24MHz-Dual-channel-Arbitrary-Waveform-DDS-Function-Signal-Generator-UK-/162052601944?hash=item25bb167858:g:sCUAAOSwXeJYH~c7 And give you a second channel for free! Bob
  17. BobK

    3mm 6v 30ma

    At 6V and 30mA an LED to replace it could be an option. You would need wide angle one and a resistor to complete it. Bob
  18. BobK

    A Christmas Gift

    An NE555 + relay would be simpler, no programming required. The button would trigger the 555 in monostable mode to turn on the relay for x seconds. Bob
  19. BobK

    More woes driving LEDs via PWM

    Before we can select an appropriate MOSFET we need to know how much current you are going to switch. Bob
  20. BobK

    Creating 5V DC

    As I suggested in post #3. Bob
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