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Recent content by laurah

  1. L

    IAP on the Philips P89V51RD2

    Anyone? Please?
  2. L

    IAP on the Philips P89V51RD2

    Basically, I just want my program to be able to save preferences changes that users make when using the program on the chip. I figured that using IAP to save a few integers would make it possible to recall those integers if there was a power cycle. I am programming in C on a Keil uVision 3...
  3. L

    very simple question about grounds in circuits...

    Thanks! That's an interesting solution...
  4. L

    very simple question about grounds in circuits...

    Maybe for someone with your knowledge! Thanks again to everyone who helped with this.
  5. L

    very simple question about grounds in circuits...

    That's great, thanks for that. What do you make of the 4.5mA flow when the the two grounds are connected? Does that make sense and how would I have calculated that without the use of Multisim? Cheers!
  6. L

    very simple question about grounds in circuits...

    Sorry, I meant to say VSS I am using a multi-tap transformer as the main power source. - 15VAC from this is rectified/regulated down to 12VDC. This goes into the dev-board that includes the CMOS. This 12VDC is rectified/regulated on the dev-board down to 5VDC to power the PIC etc. - The 12VDC...
  7. L

    very simple question about grounds in circuits...

    Thanks Brian. Could you please explain in more detail what connecting the transistor ground to the CMOS ground will exactly do? I am interested! EDIT: sorry, i meant connecting the negative supply to the CMOS ground... Added after 4 hours 19 minutes: I simulated a similar circuit...
  8. L

    very simple question about grounds in circuits...

    ahh - yes there is a bridge rectifier - the circuit will accept AC! OK - so this is the source of my 0.7V drop? If so, what do I do about it!!! Thanks for all the help people, i really appreciate it
  9. L

    very simple question about grounds in circuits...

    It doesn't unfortunately. If it is the case that it is a digital output set to low, what do I do about it? Added after 22 minutes: ahh... So I have a case of analog ground (AGND) vs digital ground (DGND)! Which one do I use?
  10. L

    very simple question about grounds in circuits...

    I don't have one sorry :( :cry::cry:
  11. L

    very simple question about grounds in circuits...

    I am using a multi-tap transformer as a power supply. I have rectified and regulated oneof the taps to generate a 12vdc steady power supply. I did this because my dev kit takes 9-12vdc that it then rectifies/ regulates down to 5v to power a programmable IC. This IC has a bunch of input/output...
  12. L

    very simple question about grounds in circuits...

    Thanks for your reply. If I connect the two grounds together then won't there be a constant flow of current from the CMOS (the CMOS "0V" is 0.7V higher than the power supply 0V)
  13. L

    very simple question about grounds in circuits...

    Thanks, that sounds like a good solution. So I would then connect the transistor emitter to the ground of the supply rather than the "0V" of the CMOS?
  14. L

    very simple question about grounds in circuits...

    Hi, I have a development board powered by 12VDC that has a CMOS 5V output pin that I can control. I want to use the 5V output to switch on a 12V relay. So I am using a transistor to avoid drawing too much current from the CMOS to switch on the relay. My problem is that the CMOS 0V is 0.7V...

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