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  1. dorke

    LDO gets hot when using a relay module?

    Let us start from the beginning: What is it that you wish to make/do ?
  2. dorke

    Controll for Seven-Segment-Displays

    Hop, that is an "arm and a leg price" ,6 Euros...what? :mad: Here it is soled for 0.99$ ,may take longer to arrive though.
  3. dorke

    Open / Short circuit time constants for pole approximation

    Ratch, This Open-circuit time constant method is supposed to be an intuitive approximate way to analyze frequency response(quick and dirty in a sense). And, you are absolutely correct : only independent voltage/current sources can be "eliminated". This isn't mentioned in the "trivial source"...
  4. dorke

    Open / Short circuit time constants for pole approximation

    Nice to hear it finally worked for you:) BTW, which book is it from?
  5. dorke

    Open / Short circuit time constants for pole approximation

    george2525, It is clear that the solution Ratch gave you is not according to the method discussed (quote: "I don't know why you would short Vsig"...),it is the conventional way. 1.from my previous drawing I replaced vbe back to be the original Vpi. 2.Since rpi is a parallel resistor it will be...
  6. dorke

    Getting Starting with LCDs

    1.To start with the Sangean has 24pins the other has only 16pins. that means they are totally non-compatible. 2.But the biggest problem usually is the internal LCD controller chip, to be compatible they have to be exactly the same IC and that you can not know with the info you have. 3.Are...
  7. dorke

    Controll for Seven-Segment-Displays

    1.I don't understand what exactly do you mean. The IC automatically scans the RAM which holds the 7 segment data to be displayed on all or part of each of the 8 segments. 2.The Rset resistor sets the current for all segments. That doesn't mean it is a series resistor it just controls...
  8. dorke

    Open / Short circuit time constants for pole approximation

    I substituted gm with 1/re This the circuit you need to solve for Rpi Here is the correct Circuit:
  9. dorke

    Open / Short circuit time constants for pole approximation

    I think they just used the relation re=1/gm. Makes any sens?
  10. dorke

    Open / Short circuit time constants for pole approximation

    Here is "trivial" source on the method for you. Try it yourself so you can learn,the explanation is clear and the method not that difficult . Post here if you have problems...I promise we shell help :)
  11. dorke

    MX-7000 Lightbard LED conversion

    Generally there are LED-bulb substitutes to almost any bulb out there. As LEDs are much more efficient they will draw less power, almost always this is not a problem for the driving source,it actually makes it "happier " . You need to look for the same 1.Lumen output (same or higher) 2.viewing...
  12. dorke

    Controll for Seven-Segment-Displays

    Hop, It is not that these specific parts are obsolete,they still make them. If that project would have been tried with Nixie-Tubes that would have been obsolete. Pepole still have fun with them and play with them(maybe driving them with relays etc.;)), but they have all the disadvantages...
  13. dorke

    Controll for Seven-Segment-Displays

    So complicated using 70's chips,why?:eek: So, you want to drive 4x 7segments displays serially(uP controlled?). There is simple single chip(24pins) solution with MAX7219/21 ,there are others as well. Here:
  14. dorke

    Why do these transistors overheat?

    Try this modified circuit:
  15. dorke

    Stereo keep on poping a fuse dont know why?

    This Amp as "only" 4 fuses: 1.Mains primary(I guess this is the one that blows,it's 2A). 2.Panel Lamp fuse 400mA 3.Secondary trans fuses 2 x6.3A Which is it? If it's the mains fuse ,,plenty of causes for it to blow...:oops:
  16. dorke

    tl431 calculations

    Vout=Vref(1+R1/R2) for R1=R2 you get Vout=Vref*2=5V So R1=R2=10k ohm is correct like steve suggested Rsup is the series resistor . In order to calculate it you need to know the following info. Maxiload=Max load current (Not "about") Miniload=Min load current (Not "about") MaxVsup (non...
  17. dorke

    Voltage drop across a 1626 tube as a rectifier??

    What is +VBB ? What is Vg? What is Rp? Draw a work line and find Vp(like shown on the pic) Here is the RCA 1626 TUBE PLATE I-V curve . Filament voltage of 1626 is 12.6V
  18. dorke

    Diodes Circuit analysis

    Ratch, This a "homework Help". You are not supposed to put the full solution, just help and give direction...
  19. dorke

    Voltage drop across a 1626 tube as a rectifier??

    The 1626 is a Triode , you need to know the grid voltage and the A-K current. like so(general example):
  20. dorke

    Schematic needed for Sprague Mike-O-Meter

    Here is what 50c could buy in 1958. Closest I could get,hope it is better than nothing...;)
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