Search results

Search Forums New Posts
  1. (*steve*)

    Boolean Expression to 2-input logic gates only

    You could also try using de Morgan's theorem and see if it simplifies anything. Alternately, just implement a three input gate with two two input gates and invert the inputs as required. Have you created a truth table for it?
  2. (*steve*)

    [SIMPLE CIRCUIT HELP/ANALYSIS] LEDs driven by GameBoy sound

    Can you post your image here. I can't see it on my phone when you post it on that external site.
  3. (*steve*)

    Theory/reality mismatch in a transistor circuit

    This should give you an idea of what you've done wrong. I have reverse engineered your breadboard layout into a schematic:
  4. (*steve*)

    Electromagnet levitation circuit LED not glowing

    The outputs of the op amps should be high.
  5. (*steve*)

    2N2222A

    Or look at my post. Hint: it has links.
  6. (*steve*)

    Using this magnetic sensor as a wakeup sensor

    I was thinking a microcontroller. You may have to deal with unusual outputs as the device is powered up or down and while it is powered off.
  7. (*steve*)

    RLC Filter for Power Decoupling and Current Sensing

    For the first one I would recommend a linear power supply. For the current if try a hall effect current sensor. Then use a microcontroller with an ADC to convert the two voltages to some value. With a 10 bit ADC you can get mA to A and resolution of voltages to hundredths of volts (depending...
  8. (*steve*)

    Using this magnetic sensor as a wakeup sensor

    Depending on the rate of change of the magnetic field, you might turn the sensor on intermittently. If you can operate it for 100ms every second, the average current drain will be 10% of what it is now.
  9. (*steve*)

    LED security lights

    So you have mains operated 50W LED security lights that are switched using a solid state relay. You want the lights to flash. Now you need a circuit to provide the signal to the SSR. You have 12V DC available. If that is right then there are a number of solutions available. You could Google...
  10. (*steve*)

    Using a logic signal to switch a load

    A transistor controlling a relay should do it. Then use the relay to control the load.
  11. (*steve*)

    RLC Filter for Power Decoupling and Current Sensing

    The sense lines are the voltage feedback. If you extend them to the load before connecting them to the output, the voltage will be regulated at the load end.
  12. (*steve*)

    RLC Filter for Power Decoupling and Current Sensing

    Decoupling won't do that. Do that locally where required rather than at the power supply. The long leads will add some resistance and inductance, so all you need add is more capacitance.
  13. (*steve*)

    RLC Filter for Power Decoupling and Current Sensing

    What's the problem (other than current measurement)? You can't measure the current in the negative rail because (although you don't state it) I bet you have a common negative. A current shunt placed between the output of the regulator and the voltage feedback circuit will allow you to measure...
  14. (*steve*)

    Resistor Value

    Last question first. If an inductor has only 2 leads (and no magnets) then it can be connected in circuit either way around. If this was an inductor, with 5 bands, typically you have a double-width silver on one end. Having a closer look now, and comparing it to the inductor colour charts, I...
  15. (*steve*)

    RLC Filter for Power Decoupling and Current Sensing

    It would be far better for you to tell us about the power source and the requirements for the load than for you to deny us this information an pose your idea of a solution. Firstly, inductors are rarely used in power supply filters these days, and for power supplies, a series resistor is even...
  16. (*steve*)

    Theory/reality mismatch in a transistor circuit

    That's an unusual circuit. You have a simple constant current driver which is supplying around 41mA (VR22 / R22). It is not 50mA chiefly because VRedLED/sub] varies significantly between LEDs. In theory, if your supply voltage is 17V and the zener has 12V across it, and R22 has 0.9V across...
  17. (*steve*)

    2N2222A

    Interestingly enough, some datasheets I found for the 2N2222a and the ZTX450 suggest they have exactly opposite pinouts (others indicate they're in totally different packages). On the basis that a 2N2222 is often specified where some random NPN transistor can be used, the ZTX450 is possibly OK...
  18. (*steve*)

    Electromagnet levitation circuit LED not glowing

    Yes, if it is constructed correctly the LED across the electromagnet should be on when there is nothing under the electromagnet. Pin 1 and pin 7 of the dual op-amp should be closer to the +e rail than the negative. The schematic shows a +/- 12V supply. Is that what you're using, or are you...
  19. (*steve*)

    Resistor Value

    That is an inductor. Look up the colour charts for inductor bands. I can't do that for you right now, but I'm sure that's the hint you need, and someone else will probably tell you the same thing (and have time to look it up for you) if you wait a short while.
  20. (*steve*)

    Bloody cats!

    Having worked in the door brigade in my state for a number of years, I have heard several stories. These are from a particular highly ranked officer who (I strongly suspect) was not a cat lover. 1) when approached by a person concerned that their cat was stuck up a tree, reply "madam, how many...
Top