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  1. Arouse1973

    Op amp power supply help

    I believe yes and yes to those questions Steve. If the opamp is driven into saturation it no longer has any voltage headroom to be able to adjust it's output to maintain this virtual ground. And although it would be unusual to use an opamp without any feedback then the same applies. It has no...
  2. Arouse1973

    PSpice does not work anymore

    Um Strange!
  3. Arouse1973

    PSpice does not work anymore

    Is it just P-spice that's not working or are any of your other programs behaving in an unusual manner?
  4. Arouse1973

    PSpice does not work anymore

    I suspect you have tried System Restore and go back a few weeks. Works for a lot of things. Adam
  5. Arouse1973

    Photodiode amplifier question

    Glad to be of assistance. Nice one. Adam
  6. Arouse1973

    Op Amp Stability

    Hi All It was mentioned that it might be use full for some people to understand a bit about some stability problems you can get with op-amps. Most of the seasoned engineers on here probably already know this and may like to make corrections to my post. I welcome constructive criticism and will...
  7. Arouse1973

    FET switch circuit - is it correct

    Hello, after all this can't you just use a toggle switch? :) only joking, I know you want to have a play with more fancy circuits . Ok so I see R1 might be in the wrong place and should pull the base of the transistor Q1 to +V otherwise your circuit will be on all the time. A couple of other...
  8. Arouse1973

    FET switch circuit - is it correct

    Yes Bobs right. You can't do this because the input will feed through one of the internal transistors to the disconnected com pin. And because the output is connected to the com pin through two series resistors you will get a voltage on the output. If you don't have a regulator with shut down...
  9. Arouse1973

    electronics revision help

    Yes I was surprised there was not more detail. Maybe it is a test for the OP to have a think and make a reasonable decision himself. Rather than being given the exact requirements, this would show the ability to do a bit of research and also show he had the ability to possibly re-arrange formula...
  10. Arouse1973

    Audio poweramp TDA2003

    Sounds good to me :) ha ha. Nice one Adam
  11. Arouse1973

    Audio poweramp TDA2003

    Ok no probs.
  12. Arouse1973

    electronics revision help

    Hi Kris The reservoir capacitor is calculated by C = I(Load)/(frequency of ripple*Voltage of ripple required), so for a ripple of 100mV at 100Hz and 12mA load approx. that's 10uF. You have to decide how much ripple you can allow for this I used 100mV but you might need less. For the low pass I...
  13. Arouse1973

    Audio poweramp TDA2003

    As Kris mentioned here it is in bridge mode. Thanks Adam
  14. Arouse1973

    Carp fishing electronics

    Sounds interesting. Is this the same thing as a bait alarm? I used to use something like this when I used to fish. Adam
  15. Arouse1973

    VTC

    Video Travel Charger. Batteries for VTC use a (LiMN, Lithium Manganese) chemistry with reduced risk of venting. They are designed to be safer for traveling. Thanks Adam
  16. Arouse1973

    Photodiode amplifier question

    Hello Comparators don't have the internal compensation capacitors that op-amps have so slew rate is of no importance. That's why it is not on the data sheet. One thing that might catch you out is the output stage maybe open collector so you will need a pull up resistor on the output. You will...
  17. Arouse1973

    Photodiode amplifier question

    Yes this is a common problem because people think a 1MHz square wave is the same as a 1MHz sine wave. The fundamental frequency is obviously the same but the square wave with have lots of harmonics which is what will slew rate limit the op-amp. The OP might be better off using a comparator if he...
  18. Arouse1973

    Photodiode amplifier question

    Yes Steve sounds like a slew rate issue to me. You need to make sure you have a high enough slew rate if using fast rising edge pulses. Adam
  19. Arouse1973

    Understanding the nature of the electric field

    I think it depends on the type of antenna you use. Whips will respond better to the electric part of the EM wave. Loop antennas will respond better to the magnetic part of the EM wave. At the end of the day it doesn't matter if you think of it as virtual photons or as mentioned strings. The...
  20. Arouse1973

    Function generator and impedance

    What so you connect a 50R load to your sig gen and then what connect an 8R or 4R load across this. If so what's the 50R load doing. Thanks Adam
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