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  1. BobK

    Creating logic AND gate with 2N222 Transistor

    Not cheating. From memory 0.8 and 2.5? Bob
  2. BobK

    Creating logic AND gate with 2N222 Transistor

    Sunny. His problem is that when the second input is activated, the LED sees the base-emitter current through the second transistor. Moving the LED to the collector as I suggested would solve this problem. Not that a pulldown is not a good idea as well. Bob
  3. BobK

    Troubleshooting: Why the normally closed and normally open pin in my relay is shorted internally?

    Care to clue us in? Bob
  4. BobK

    would like to build a radio transmitter

    Do you understand what an IC is? It is not something you can make. As others have hinted, it takes many millions of dollars worth of equipment to make an IC. So, you do not want to make an IC. Now, the question is, what do you want to make, and for what purpose? Bob
  5. BobK

    Creating logic AND gate with 2N222 Transistor

    Move the LED to between the top collector and the positive supply. Bob
  6. BobK

    Power Relay needed

    Most LEDs will not light up at 1.5V. What color is the LED? Hopefully red, they are the lowest, but typically they still need about 1.8 to 2.0V. You might need something like a Joule Thief to get it to run reliably at 1.5V. Then you have the problem of comparing the voltage. A standard...
  7. BobK

    Cheapest way to get data from multiple(100s) of sensors?

    smaller, fewer pins to solder. Bob
  8. BobK

    Cheapest way to get data from multiple(100s) of sensors?

    A 3.3K or a 10K would work fine. If you want to do much in electronics, buy a resistor kit on Ebay which will contain hundreds of resistors for a few bucks. Bob
  9. BobK

    Troubleshooting: Why the normally closed and normally open pin in my relay is shorted internally?

    Another possibility is that you have misidentified the pins. Bob
  10. BobK

    Help with motion sensor and motor DC

    If it works with the 470Ω resistor, then it is likely a push-pull output. It would not work if it was open collector. To know what resistor to choose you need to know how much current motor takes and how much voltage the sensor outputs. Let's say the voltage output is 5V and the current drawn...
  11. BobK

    Electronic System Design

    Let me google that for you Bob
  12. BobK

    8,16,32 bit controllers

    Trying not to be snarky for once: The 8, 16 or 32 bit designation of a microcontroller refers to the largest size of data can be processed by a single instruction. I.e. an 8 bit processor can add two 32-bit numbers, but it will likely take 4 or more instructions. A 32-bit processor can do it...
  13. BobK

    Push Button H2O - Reversing Polarity

    I agree with Steve. One of my pet peeves is remotes that have a "power" button. When operating more than one device they will eventually get out of sync and you will turn some on and others off. If they had an "on" button and an "off" button, this would never happen. Do you have some way of...
  14. BobK

    vehicle external projection using laser beam on outside environment

    Especially if you can get people on a forum to design it for you. Bob
  15. BobK

    vehicle external projection using laser beam on outside environment

    Then talk to your lawyer. Bob
  16. BobK

    MP4 Amplifier

    Did you try the datasheets? They normally give a standard circuit. Bob
  17. BobK

    High Power Exclusive OR Gate Help

    You could start by telling us what are the two inputs that you want to combine with a gate. And then tell us how you want to output to behave. There may be high power gates implemented somewhere, but any gate can be made "high power" simply by using it to drive a transistor or MOSFET. This is...
  18. BobK

    Pushbutton circuit

    Who said they were connected to an MCU? Bob
  19. BobK

    Fixed Current Limiting for all USB Ports?

    Where do you expect the 500mA to go when nothing is plugged in? You cannot make a USB port output a fixed current, the current it outputs will depend on what is plugged in. A constant current supply varies its voltage in order to control the current. But that would not be a USB port, since it...
  20. BobK

    Cheapest way to get data from multiple(100s) of sensors?

    Yep, that is the idea. Another way to do it is use a microcontroller with enough pins to drive all the rows and all the columns without using a shirt register. That would be 40 outputs. Bob
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