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  1. (*steve*)

    Current sensing circuit help

    And your circuit should have NO connection to mains earth. The circuit floats above ground. Any earth connection will effectively be a short circuit to ground and cause some amount of fault current. If you have earth leakage breakers, such an earth connection will likely trigger them.
  2. (*steve*)

    Current sensing circuit help

    Two 10V zeners will be fine. Nothing (other than the isolation provided by a transformer) will make it safe if there is any access to the circuit. The resistor in series with the capacitor is there to act as a fuse for when the capacitor fails. A resistor in the neutral line makes it less...
  3. (*steve*)

    Current sensing circuit help

    The thing you have to realise, is that EVERY point in that circuit can kill you. If you have an isolation transformer, use that. If not, have someone with you who can call an ambulance and perform CPR on you until it comes.
  4. (*steve*)

    What is this?

    Probably a battery protection circuit to prevent you from over-discharging the battery.
  5. (*steve*)

    Who knows how to test N-Ch. MOFETS with Multimeter? Please HELP!

    Or the diode check range which has a higher open circuit voltage.
  6. (*steve*)

    Current sensing circuit help

    FFS! THE JUNCTION OF THE TWO ZENERS IS THE CENTER OF YOUR SPLIT SUPPLY FOR THE OP AMP DON'T CONNECT THE 'KING MAINS TO THE LOW VOLTAGE SIDE. AAAAAAGH! So that circuit is correct so far. Remove the ground connection from the mains and place it between the zeners. It allows you to get rid of...
  7. (*steve*)

    Current sensing circuit help

    Well, do you remember that you were originally taking the voltage from both ends of a zener? Now you have two zeners together that give the same voltage, bit now with a mid-rail generated between them.
  8. (*steve*)

    LED setup help needed.

    A microcontroller would be the simplest solution (for a certain definition of simple).
  9. (*steve*)

    Current sensing circuit help

    The point between the two zeners is your middle rail. DO NOT connect it to the mains as you have done.
  10. (*steve*)

    Current sensing circuit help

    I would not recommend it. It would be better to replace the single 14V zener with two zeners of approximately half the voltage and place a 10uF capacitor across each. Also ensure that your capacitor C1 is rated to be placed across the mains. If it fails, everything in your circuit is likely...
  11. (*steve*)

    regarding (d3s ic) dual transistor npn pnp

    Your question is very confusing, as is the fact that you reported your own post.
  12. (*steve*)

    LED for electric heater (UK)

    If you purchase a neon indicator that is specified for your mains voltage then it will have an appropriate resistor built-in. This is NOT what you want. In this case they suggest the resistor you would need for 240V. This would be appropriate. You will note that it is rated for (in this case)...
  13. (*steve*)

    Vintage Schematic Questions

    In my opinion, it would be best to add a zener diode in series after the silicon diode with a value similar to the forward voltage drop of a selenium rectifier stack. Loading the power supply by reducing the value of the resistor across the capacitors is just going to increase ripple and...
  14. (*steve*)

    LED for electric heater (UK)

    Nothing will be shorted. The neon indicator lamp (with its accompanying resistor) will be placed across the thermostat. When power is applied to the heater and the switch is on, the heating element will me supplied with power either through the thermostat (turning on the main power light in...
  15. (*steve*)

    Current sensing circuit help

    With a transformerless power supply (which I interpret as using a capacitor) you should connect NOTHING to mains earth. The earth connection you have in your simulation is probably required to make the simulation work. With this type of power supply you need to treat the correct as if each and...
  16. (*steve*)

    Current sensing circuit help

    1.8uV is plenty close to zero. You have missed a ground connection (on one side of the current transformer -- near D1 on your diagram). And I see you worked through the other questions you had :)
  17. (*steve*)

    Current sensing circuit help

    I haven't drawn the mains side. The current transformer has a resistor across it. Ideally you pick the value of the resistor to have about 0.5V across it at the maximum load. In your case, you can increase the value of the resistor to increase sensitivity. For the highest sensitivity you...
  18. (*steve*)

    Phone's car charger

    Did you use low ESR capacitors, and did you have 2 different value capacitors (47uF and 470uF)
  19. (*steve*)

    Current sensing circuit help

    It looks looks you ignored most of my advice. In addition, you're now not using the current transformer correctly. I'll draw you a circuit... Hang on
  20. (*steve*)

    Current sensing circuit help

    I would build 2 circuits. One using the 1:100 current transformer, and the other using the 1:1500 current transformer. It also might be useful if you can post the circuit you're using now so we can see how you've changed it. And... are you hoping to get an accurate measure of the power consumed?
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