Recent content by jpp412

  1. jpp412

    lm7812 problem

    I haven't even connected any load to it yet - the regulators are cool.
  2. jpp412

    lm7812 problem

    Hey Audio, Yes it is about 18v according to the DVM.
  3. jpp412

    lm7812 problem

    I don't think that's the problem - at least based on what I had ordered the 7812 was from TI and I used the pinout on their datasheet.  However is there someway I could check it? - short of removing it from the circuit and using separate test circuits?
  4. jpp412

    SAMPLES

    CHeck out the post on "electronics chit-chat" forum for a pretty good list.
  5. jpp412

    lm7812 problem

    I have a problem with a 7812 in a power supply such that the output voltage (measured with a dvm) is only 9.5v.  I at first thought the 7812 was bad so I put a new one in and still getting the same results. I have a 7805 and 7905 in the same supply that work fine. Any thoughts?  Is is...
  6. jpp412

    lm339 comparator

    Thanks Audioguru.  Your explanation helped alot.  I'm going back through their ex apps with this in mind to see if I can make sense of it now. Thanks again! Joe
  7. jpp412

    lm339 comparator

    I'm trying to understand the function of the 339.  I have read all of the datasheets (which don't help very much as far as basic understanding) and think that the basic idea is to output high when the + input is > the - input and a low otherwise.  Is this the correct basic idea? Beyond that...
  8. jpp412

    Variable digital resistor???????

    You can just buy the digital pot - check out digikey.
  9. jpp412

    Has anyone implemented the 8 line tele intercom?

    Sorry about that. Here is the link: http://www.electronics-lab.com/projects/telephone/017/index.html
  10. jpp412

    Has anyone implemented the 8 line tele intercom?

    I'm trying to figure out the microcontroller program.
  11. jpp412

    Help on the Link 4+0 circuit

    Has anyone built this circuit that could help with my questions? Also, I noticed another circuit ("8-line telephone intercom") posted by someone else - is that a better design for me to try instead of the link 4+0?
  12. jpp412

    Help on the Link 4+0 circuit

    Hey Austin et al: I am new to this forum and am interested in building the link4+0 for personal use. 1. However, I am somewhat new/inexperienced with this type of thing. I don't see any identification of the parts required to build. Most of them I can figure out by looking at the previous...
  13. jpp412

    Notes on the Link intercom

    Hey Austin et al: I am new to this forum and am interested in building the link4+0 for personal use. However, I am somewhat new/inexperienced with this type of thing. I don't see any identification of the parts required to build. Most of them I can figure out by looking at the previous design...
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