Search results

Search Forums New Posts
  1. dorke

    Finding Distance for Boundary btw cell towers.

    Well, The boundary is at a distance D in which the receiving level is the same from both towers. PrA=PrB. All factors cancel out since they are equal(height,gain,frequency,polarization etc.)except the difference in transmit level. The signal attenuates according to 1/r^2.
  2. dorke

    Current meter

    In this case the simplest thing to do is to measure the current that the radio draws when off. There should be none. You can also physically disconnect the radio,and see if the battery is still drained.
  3. dorke

    Serial communication problem.

    Now I'm confused. I thought all 4 images on #27 are measurements taken on the INPUT of the Max chip,aren't they?
  4. dorke

    Analog to 1-Bit Digital Signal at a Threshold

    "Can an analog signal into a digital triggering port damage the DAQ?" Yes, if it violates the min. or max. allowed input voltage of the DAQ. "Will this method work for my application? " Yes,In general . "Is there a better way of achieving my goal?" You need to specify what is the anolog...
  5. dorke

    Current meter

    Since an element that drains the battery is usually "constant current". you don't need a "current logger". An Amper-meter is what you need. Connect it in series with the battery. important !!! don't start the engine!!! it will blow the DMM internal fuse. Now check the current with the car...
  6. dorke

    Schematic for old outboard motor switchbox

    You can contact Mercury here ,for help/schematics etc. Or consult on this "boating forum" here. Good Luck.
  7. dorke

    I just thought I'd measure a few diodes V vs I

    Steve, It is a very good handbook ! Here is a "simple minded" practical solution to eliminating the "diode limiter protection" effect on the measurement: Connect the limiter to the input(one end) with a SPST, normally closed ,momentary push-button. It will provide protection when...
  8. dorke

    Interrupt latency time calculation

    Generally there is no way to calculate the interrupt latency accurately. The reasons are : 1.The interrupt priority structure is a non deterministic factor(unless you are talking about the top priority interrupt). 2.The code may contain periods in which interrupts are disabled. 3.Upon an...
  9. dorke

    Please help identify this variable resistor

    Yes there is a term: Yours is called "rear adjust" the Digikey one above is "top adjust". This one has this option. Looks different dimensions and ears,may be you could improvise with it.
  10. dorke

    Please help identify this variable resistor

    Looks fine. You should measure the mechanical dimensions of the one you have and compare them to the datasheet of the potentiometer here. Especially the 5 pins (2 mechanical) distance and diameter. The shaft length,diameter and style(teeth number). The one you chose is 10K linear,single, with...
  11. dorke

    Please help identify this variable resistor

    This gadget was once called "a light organ" (like a John Travolta disco dancing floor). Since as you say it is from the 70's the writing on the pot "A 10K",means a 10K linear potentiometer. Why do you need to replace it? Did you try spray it with Deoxit?
  12. dorke

    Unspecified capacitor

    Is this from a Metz 44 AF-4 ? The 331 code is probably 330WV . The capacitance value isn't written on it ,it is probably coded. What does the schematics say? You can also inquire directly with Metz Here.
  13. dorke

    Serial communication problem.

    No ! you shouldn't connect a PSU directly to the Tr. like you discribe, it may destroy it! Use it with the biasing resistors as shown in the circuits. There is no need to test the circuits "under voltage", They should be analyzed "on paper" first, it is not complicated,and we can help you...
  14. dorke

    Serial communication problem.

    I think we are actually dealing with the same topic,"A design of an RS232 receiver". This is done from several angles, so could stay as is . Let's take a step by step examination: look at your circuit with input voltage at "Space" (>+3V). What is the output voltage Ve(Emitter to GND)...
  15. dorke

    Serial communication problem.

    "Why do i have to connect emitter to "gnd" and collector to vcc ? " I'm re-posting from #45: "Another practice question for you: Looking at #34 circuit, Can you "estimate" at what rs232 input voltage will the output be 0-volts?" Add the same question for the output at "Vcc". Try to answer...
  16. dorke

    Looking for a high current darlington transistor.

    The MJH6287 could be a candidate. Is the darlington the only solution for you?power-mosfet?
  17. dorke

    Serial communication problem.

    Well, Again not quite correct. The "reference voltage" for the RS-232 input to compere with should be zero volts. It is not the case in your circuit,Vbe is not "referenced" to ground but rather to "VCC". Look at the correct diagram below. The B-E junction is the one to be protected,look a the...
  18. dorke

    Serial communication problem.

    Hop, A few notes: 1. The 20mA current, was and still is called "Current Loop". 2. Here is an article on the History of Mark and Space. 3. Here is ITU-T V.1 ,a standard which explains why and how were the voltage levels and logic levels of Mark and Space chosen. Surprise... not arbitrarily...
  19. dorke

    Serial communication problem.

    Another practice question for you: Looking at #34 circuit, Can you "estimate" at what rs232 input voltage will the output be 0-volts? "ttl signal is idle 0V and high 5V". Well not quite,there is no "idle" definition for TTL. It has 2 logic levels "0" and "1",their interpretation could be...
  20. dorke

    Serial communication problem.

    Here is a very simplified explanation: In the schematic above the transistor is used as a "switch" which has 2 states "on" and "off". The functionality is of a logic inverter. Unlike a "pure logic device" ,it has different input and output voltage levels i.e it performs voltage...
Top