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  1. dorke

    8051 power supply

    Welcome to EP. To answer your question we need to know more details like: What is the total maximum current needed from the 5V supply. How "clean" and stable should the 5V be. Size limitations of the P.S etc. Assuming you don't intend to operate very accurate analog circuits,only digital stuff...
  2. dorke

    Resistors or not?

    If they are listed as "12V" they need no resistor. They should be the automotive type,"stealing" 12V from existing 12V sockets in a car, via the black female connector/adapter inserted instead of a light bulb. The LED matrix with the male connector is then plugged in the female to supply the...
  3. dorke

    Resistors or not?

    Do you have parts numbers? Look in the datasheets, there is your answer.
  4. dorke

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    The readings are fine. IC601 seems O.K. Please remove the connection to GND from Z601. We are ready for the repair job.
  5. dorke

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    It looks o.k. No obvious bad readings. Could you please connect the center pin of Z601(the white 3 pin resistor of the bad channel) to chassis GND and measure DCV on pins 5,6 and 7. After you measure remove the connection to GND from Z601.
  6. dorke

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    Pins 4 and 8 should be about ±17V they are fine. Pins 1,2,3 should be in the mV (milivolt = 1/1000 Volt ) range. So no, -262V is not possible here,(now I understand why you said "electrocute myself";)) Same for pins 5,6,7,but this is the bad channel which is now in "open loop" state, so...
  7. dorke

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    Yes it will.
  8. dorke

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    Yes, to all your questions.
  9. dorke

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    Hi Iceman, I don't know when you will get the parts and when you will start reconstructing the unit. I'm may be busy for a couple of weeks. Let me remind you of the missing DCV measurements of IC601 ! The repair work should be done gradually. Here are a few guidelines for the "1st phase of...
  10. dorke

    Is there any particular reason this won't work? Thanks

    Looks like you are trying to build a two stage 5Mhz RF transmitter. If that is indeed what you are trying to do,it will not work. As said above: 1.No bias for the transistors. Plus: 2.R1,R3 values very high,should probably incorporate RF chocks. 3. No tuning for transformer T1/T2. 4. No...
  11. dorke

    Trying to make a transistor cancel another transistor

    Thanks Hop, Interesting as always. The hole book " Practical Design Techniques for Sensor Signal Conditioning" can be found here ,it is a 1999 book ,not up to date, but still good. the "Analog-Devices Library" has other very good books as well,here. Note the 60s Ray Stata op. amp. articles. ;)
  12. dorke

    Trying to make a transistor cancel another transistor

    Hop,I'm not blaming ,just correcting. Chris,I did catch it on #51 but the difference is hop did say: "more or less linear over the temperature range in question",it can pass... more or less;) while in #54 you said "Thermistors are linear devices",that doesn't pass. Hop,as usual, is...
  13. dorke

    Trying to make a transistor cancel another transistor

    Yes you can...;)
  14. dorke

    Trying to make a transistor cancel another transistor

    @CDRIVE, my time to correct you. Thermistors are not linear devices ! They are in fact exponential ones in regards to temperature.
  15. dorke

    Trying to make a transistor cancel another transistor

    Don't agree on that one. That will totally miss the point of learning analog electronics and concepts. It will move the all thing into the "software realm" which isn't the point here at all. One thing I do agree on, the implementation I suggested is indeed a kind of A/D...a flash A/D is build...
  16. dorke

    Trying to make a transistor cancel another transistor

    Yep, we did it again. I can say the spellchecker(and the late hour) is Drowning me indeed:( BTW,If you are around,what do I need it anyways ;) Will correct it ,thanks.
  17. dorke

    Trying to make a transistor cancel another transistor

    @CDRIVE ,What "tool" are you using for drawing and simulating? Looks like a nice one.
  18. dorke

    Trying to make a transistor cancel another transistor

    Yes @CDRIVE, I 'm correcting that :)
  19. dorke

    Trying to make a transistor cancel another transistor

    After you have played around with discrete transistor and learned what you can. It would be time for a more general lesson: Comparators 101. These are very basic and important building blocks with numerous useful applications. The thing you are trying to build is basically a classic job for...
  20. dorke

    Signal flow fundamentals

    Your question is a fundamental one in the theoretical field of Signals and System. The general answer is No. That said,you have to define more exactly the following terms: 1.signal. 2.circuit. 3.introduced. 4.appears.
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