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  1. BobK

    Driving LEDs from var power source - Efficiency

    Is there a reason you want to use 84 LEDs adding up to 7.5W? High power LED's designed for lighting are actaully much more efficient than the indicator LEDs you are likely using. Most likely you would get more light out of a single 3W LED. Bob
  2. BobK

    simulation software

    What Harald said. LTSPICE is a great product and is free. It has the easiest schematic capture I have ever used, and nice graphics for the simulation output. I use it for all my analog simulation. Bob
  3. BobK

    no of pin issue- smart card chip( 6 or 8 contacts) and microcontroller(40 pin)?

    The 8051 is an archaic microcontoller. Microcontrollers today range from 6 pins to hundredes of pins depending on how much I/O they need. Look up PIC and AVR for examples of modern micontrollers. These chips have basically everything you need on board: program memory, data ram, eeprom...
  4. BobK

    Isolate the output of a simple low pass

    Low output impedance means a load will not reduce the output voltage as much. Thik of it as a resistor in series with the voltage source. Of course, it is relative. An opamp might have an output impedance of hundreds of Ohms, while a high power audio amp is going to be a fraction of an Ohm...
  5. BobK

    Isolate the output of a simple low pass

    Yes, you can use an op-amp in voltage follower confguration. Bob
  6. BobK

    epicly easy question

    That would be parallel. A series circuit would go like this: +lead from USB to + lead of first fan - lead from first fan to + lead of second fan - lead from second fan to - lead on USB. Bob
  7. BobK

    Creating an ASIC chip in a lab

    Oh, and you can put an entire high-end microprocessor on an FPGA these days. So unless you are talking about analog circuitry, and FPGA would do it for you. Bob
  8. BobK

    Creating an ASIC chip in a lab

    To make a chip you need a clean room and equipment costing many millions of dollars. I don't think you want to try this at home :) Bob
  9. BobK

    Query about circuit

    They should be the same. Re-check your circuits. BTW: What do you mean by "nearly lit up"? If it did not light up, how can you tell that it was "near" lighting up? Bob
  10. BobK

    resistor tampering

    Don't think of resistance, thing of conductance. How could taking material away make it conduct better? This is what you (wrong) answer implied. Bob
  11. BobK

    What are the main components in electronic engineering?

    You really don't get it do, you. Here is a calculation for you. First, lets see how many microchips we can make from 1 cubic meter of sand. High end microprocessors such as those made by Intel are the largest chips made, and are about 1 square cm of silicon, 775 um in thickness. Let's...
  12. BobK

    Pls help decode

    65mcd = 65 millicandella, is the light output. 2.1Vf is the forward voltage. The voltage drop across the LED when at operating current. Ifmax = 15mA is the max forward current. So, the operating characterisctis of this LED are the it will draw 15ma when the voltage across it is 2.1V and...
  13. BobK

    RF/WiFi Relay

    You would think someone else would have done this. Oh they have! http://www.ebay.com/sch/sis.html?_nkw=4+Channels+RF+Wireless+Remote+Control+Module+relay+pcb Bob
  14. BobK

    What are the main components in electronic engineering?

    Sandpits everywhere. Bob
  15. BobK

    What are the main components in electronic engineering?

    I expect that the amount of silicon used in construction (i.e. concrete) dwarfs that used by the electronics industry. Bob
  16. BobK

    Weird LED circuit problem

    You need a resistor in series with the LED. https://www.electronicspoint.com/got-question-driving-leds-another-work-progress-t228474.html Bob
  17. BobK

    What are the main components in electronic engineering?

    Silicon is very rare, it is only 27.7% of the earth's crust! I think you should try to corner the market. Reference: http://hyperphysics.phy-astr.gsu.edu/hbase/tables/elabund.html Bob
  18. BobK

    AC to transistor in tuner circuit

    Agreed if you truly need a signal that goes above and below ground. But you can also amplify AC signals with a single supply. You just connect to the + input to a divider at half the supply voltage and couple the signals via capacitors. Example...
  19. BobK

    energy and power signals

    Power * Time = Energy Bob
  20. BobK

    netlist simulating software

    LTSPICE from linear technologies is free and quite good. http://www.linear.com/designtools/software/#LTspice Bob
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