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  1. dorke

    Please help identify this variable resistor

    Congratulations, We love happy endings... Just for curiosity and the fun of it , Can you please measure the resistances of the SCR you pulled from the board.
  2. dorke

    Doubt about it 6-to-64 decoder

    You would use four 74hc154 and one 139, for a total of 5 instead of 9 ICs. What is this decoder for there may be other implementations.
  3. dorke

    Doubt about it 6-to-64 decoder

    That line is connected to E2 . It can be used as X6 if you need another address bit to create a 7 to128 decoder. If unused, it should be connected to "1" constantly. BTW, you can used the 74154 to reduce the chip count.
  4. dorke

    Antique Automotive Resistors

    "I need to be assured of your intellect before I continue to post here...." So you do,do you? That saying deserves putting you on my ignore list, Consider yourself ignored!
  5. dorke

    Please help identify this variable resistor

    You are welcome Hop my friend,it's my pleasure:)
  6. dorke

    Please help identify this variable resistor

    In this case the switch position has no influence on the measurement. The breakdown voltage is the point at which the SCR will fail( be destroyed) if reversed biased. It will be reversed biased since it is connected(A-K) to AC. So,In principal, the higher this voltage the better.Operation will...
  7. dorke

    What does this OLD power cord go to?

    Welcome to EP, Looks like something from Edison's Lab ;)
  8. dorke

    4-20ma signal output based on 12 hour clock

    Welcome to EP. A uController with a 24 hour timer and a D/A could do the trick. It will be an all software project. There may be a need to convert the output voltage to current,
  9. dorke

    Please help identify this variable resistor

    Yes, That is the gate like you described and the drawing shows. Max sensitivity is the pot. at full resistance ,should be the same as " max light intensity" on the panel. Please add this check 6. Measure resistance between the Gate of the SCR and the mains cable (both points! ) when the switch...
  10. dorke

    Please help identify this variable resistor

    O,k So we have a load of 4*7w=28W hence a 1A or higher device should be fine. Yes, The resistance measurement is effected by the wiring of the board and other devices connected to the SCR. But,we can still measure and have conclusions. Here we go: 1. Disconnect the devices(audio,light...
  11. dorke

    Please help identify this variable resistor

    That SCR1590 is indeed "untraceable". It shouldn't worry you at all,a "proper" replacement device can be found easily. We can guide you with that later on. It probably should be a 200V or so device, power handling my very and depends on the power of the light chain,can you estimate it? The gate...
  12. dorke

    Please help identify this variable resistor

    A DMM is short for Digital Multi-Meter a tester for voltage/current/resistance etc. Yes,the audio transformer is fine. The SCR is the main suspect(assuming no leakage through board "dirt"). I would start with cleaning the board with rubbing-alcohol and cotton-swabs. If you have a DMM you...
  13. dorke

    Please help identify this variable resistor

    The 2 gates are driven by different R-C networks, hence it is a 2 spectrum device. Besides, If it where a single spectrum device there would be no need for 2 SCRs ,one would do the job;)
  14. dorke

    IR2110 Functional Block Diagram

    There are some other App. Notes that can help: AN-1092 DT92-2A
  15. dorke

    Please help identify this variable resistor

    You are correct,the circuit is not complicated . The item you have encircled in blue is an audio isolation transformer. There are 2 identical channels each has it's own SCR( red). See a typical circuit diagram below (3 channels). Could you please try to produce a circuit diagram by following...
  16. dorke

    Using An Oscilloscope

    What do you mean when you say: "a circuit that is also powered by 120"? Can you show a circuit diagram of what you need to probe? That is the most common of equipment and usually there should be no problem as long as your prob ground is connected to the ground signal on the board/equipment you...
  17. dorke

    IR2110 Functional Block Diagram

    AN-978 explanation of how the IC works relates to a different "block diagram" than the one in the datasheet. You can find it on page 3,figure 2. So let's refer to it(below). About your questions: 1.Will the narrow pulses be like this? No way to know, since there are no details about how the...
  18. dorke

    IR2110 Functional Block Diagram

    Well, The block diagram is merely a conceptual thing. You shouldn't take it to be complete or accurate. Look at the AN-978,you can find a "different block diagram" at fig.2 page 3 ! You are thinking of the S-R -Q block to be implemented like the "school dual crossed gates" and thus are...
  19. dorke

    IR2110 Functional Block Diagram

    SD,stands for Shut Down. Looking at Figure. 1 in the data sheet revels that for SD=0 or 1 the output is well defined. Why do you think SD=1 will cause any problems?
  20. dorke

    Not getting the desired output for the circuit given

    Welcome to EP. 1. It looks like one connection is missing in your circuit: Pin 1 and 2 of the IC are not connected as they should be,see below. 2. notice the scope says "waiting for trigger",better put it in type="Auto trigger mode". 3. You should use colors of Leds as shown in the paper.
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