Search results

Search Forums New Posts
  1. Arouse1973

    Embarrassingly noobish FET questions...

    For high voltage and current I would always go for a IGBT first. They are a cross between a BJT and MOSFET. Drive then like a Mosfet and the output is a BJT so has the large current and high voltages of a BJT but low current drive of a MOSFET. You loose the intrinsic diode but gain thermal...
  2. Arouse1973

    Hi everyone!

    Hello Ally Adam
  3. Arouse1973

    Hi everyone!

    What ,...........white choc-chip cookies Dave :)
  4. Arouse1973

    Alternate to LM358

    Unfortunately I think you are going to have to pay a bit more for the op-amp unless you can run the opamp from a slightly higher voltage and then you could go for a standard type. I have had a look quickly on the major players and they all seem to be between £1.50 and the £2.00 mark.
  5. Arouse1973

    Alternate to LM358

    What for all devices?
  6. Arouse1973

    Alternate to LM358

    You need to look for a true rail to rail op amp like the LT1490A but you may have to look for a cheaper type. This allows input voltages that include the supply rails and has rail to rail output also. Adam Edit: Have a look at Microchip also. They tend to be cheaper than most...
  7. Arouse1973

    Alternate to LM358

    You might have trouble finding a cheap one because of the common mode input range of most op amps being less than the supply voltage you need one that does include the supply. I'll have a look for you. Adam
  8. Arouse1973

    input capacitance opamp non inverting buffer

    You could try and place a small capacitor across each sense resistor, similar to how a scope probe works. You might only need these with the larger values of resistors. Also run the resistance measurement part of the LCR at a much lower frequency. Adam
  9. Arouse1973

    Using a bipolar transistor to turn a load on and off

    When the transistor is used as an emitter follower (remove base resistor) and the base voltage is the same as the collector voltage which is quite common for current amplification, ok you loose a diode drop of voltage which is usually acceptable. This configuration develops more power in the...
  10. Arouse1973

    input capacitance opamp non inverting buffer

    Great, let me have a look.
  11. Arouse1973

    Does anyone know what this component is????

    Yep I agree 100uH choke.
  12. Arouse1973

    input capacitance opamp non inverting buffer

    You don't actually say what your problem is, but I am guessing you are not getting the desired results you were after. It's really difficult to comment without seeing a circuit diagram. Please supply a clearly drawn circuit diagram with the following: 1) List any measured voltages and label...
  13. Arouse1973

    Coulomb's Law in practical life!

    Ok so here's my stab at it. Don't Laugh :) Coulombs Law F = Ke * q1 * q2 / r2 q1 = Charge 1 in coulombsq2 = Charge 2 in coulombs r = Distance between the two objects in meters F= Force between the two objects in Newton’s Ke = Coulomb Constant Example 1 This is the original assumption made...
  14. Arouse1973

    Using a bipolar transistor to turn a load on and off

    No Probs, easy to make mistake. I do it all the time as you know. I'll have a look at the rest of the document in more detail. I don't expect there will be anymore :) Adam
  15. Arouse1973

    Coulomb's Law in practical life!

    Very informative, I have never done anything with electrostatic speakers. I shall look into this further as this sort of thing interest me greatly. Cheers Adam
  16. Arouse1973

    Using a bipolar transistor to turn a load on and off

    Nice work Steve. Ok I am going to probably embarrass my self now. The magic number 3 is that multiplying the current? So the transistor could draw 900mA? With a gain of 100 isn't it 466.7R and not 4667R. Just can't work out how you did it. Cheers Adam
  17. Arouse1973

    I've got to do something with it.. can't just leave it hanging

    I used to use antenna tubes for my helicopters. Feed the wire through the tube and use the rubber end stop to secure the end and the tape any left over to the tube. Cable tie this to one of the skids. Depends how big the heli is also and if you have room. Adam
  18. Arouse1973

    Coulomb's Law in practical life!

    Thanks Bob, you learn something everyday. Ah so a point charge of 1C would have a massive attraction on another point charge of 1C. Is the attraction dependant on distance between the plates? F=(1/2QV)/d if so how do you factor in surface area? Thanks Adam
  19. Arouse1973

    Coulomb's Law in practical life!

    When you put a large amount of charge on a capacitor on one side what do you think happens to the other side? Well it pushes the same amount of charge away from the other side. So your net charge is zero, which means no force between the two plates, that's why they don't implode. Adam
  20. Arouse1973

    Coulomb's Law in practical life!

    Yes but this is for a stationary amount of charge. You need to look at Amperes Law as shown in Harald's Link.
View older results
Top