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  1. Replies
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    That looks like the B+ current is (278-264)/0.1 =...

    That looks like the B+ current is (278-264)/0.1 = 140mA which is far too much yet there is no cathode voltage on the 6V6. Check its cathode/470R/22u cap isn't shorted to ground.

    Edit: Check the...
  2. I'd use the last circuit from the the link in...

    I'd use the last circuit from the the link in post 10. It uses a single dual op-amp (TL072) and it doesn't need a +/- supply. It will run off a single 9V battery so you could use a regulated DC wall...
  3. Yes, do that and remove the cap between the...

    Yes, do that and remove the cap between the chassis and the Line Reverse switch (aka death cap)
  4. The green trace is the load voltage. 57395

    The green trace is the load voltage.

    57395
  5. I've edited my post. It wasn't clear that I meant...

    I've edited my post. It wasn't clear that I meant the value Hammond chose.
  6. I'm sure you are correct (assuming the same...

    I'm sure you are correct (assuming the same conduction angle)
    I wonder why Hammond chose the value the did?
    I'm sure I've measured Iac to be greater than 2*Idc on a few occasions in the past for...
  7. V (Avg) D.C. is the average value of the...

    V (Avg) D.C. is the average value of the rectified waveform without filter capacitor so it shouldn't be listed in any of the examples with a capacitor.

    It is possible for Iac to equal Idc for the...
  8. Care to point out the nonsense for us? :)

    Care to point out the nonsense for us? :)
  9. This might come in handy. 57370

    This might come in handy. 57370
  10. Replies
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    57234

    57234
  11. Replies
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    Something like this would do it if you want the...

    Something like this would do it if you want the gain to be greater than unity.
    Adjust R1 to set the bias point. Adjust R5 to set the gain.
    Gain is 1.5 (3.5dB) in the example below.

    57163

    57164
  12. Thread: Egnator 40

    by Dave H
    Replies
    60
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    1,086

    It's a new one on me too. 2o's = secondaries

    It's a new one on me too. 2o's = secondaries
  13. Replies
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    It won't work like that, You have the source and...

    It won't work like that, You have the source and gate at the same potential which will turn it hard on. If you want to use it as a gain stage by taking the signal from the drain resistor then it...
  14. Question 3: Accents are funny things. I'm only...

    Question 3:
    Accents are funny things. I'm only 25 miles from Liverpool but can't understand a word they say.
    I noticed Less Paul and soddering iron when I was in the US. What about laboratory? It...
  15. I think it's CF grid to cathode voltage that's...

    I think it's CF grid to cathode voltage that's the problem. The CF grid is directly coupled to the plate of the driver stage. At switch on from cold when neither tube is conducting the CF grid will...
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    Is this the correct schematic? 57102 It could...

    Is this the correct schematic?
    57102

    It could be that the power tubes warm up at different rates and you are getting single ended hum before the are both fully conducting. The hum pulsing with...
  17. Thread: soldering irons

    by Dave H
    Replies
    27
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    1,728

    If there's a bend in the lead I cut it off flush...

    If there's a bend in the lead I cut it off flush with the board on the component side then remove the cut off end from the solder side. It's better to write off the component than write off the board.
  18. Replies
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    The 2M2 and 330k are a potential divider to...

    The 2M2 and 330k are a potential divider to reduce the EL84 bias voltage to -11.6V. I don;t know why they didn't just split the 330k. They could have saved two whole resistors that way. I'd adjust...
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    970

    It's looks like a LTP to me but with a negative...

    It's looks like a LTP to me but with a negative supply to the tail and grids referenced to ground. The negative feedback isn't bootstrapped to the tail which makes the outputs unbalanced. They have...
  20. Increasing the cathode resistor won't have much...

    Increasing the cathode resistor won't have much effect on gain because it's bypassed with 22u. It just shifts the bias point. You could remove the 22u bypass cap for a 6dB reduction in gain.

    I...
  21. Replies
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    And you could always measure across the two 0.33R...

    And you could always measure across the two 0.33R resistors in series to double the accuracy.
  22. Replies
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    The bias current won't adjust but what does it...

    The bias current won't adjust but what does it measure? To set the bias current I'd disconnect the output transformer and speaker otherwise a small offset voltage on the output could result in more...
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    It's a letter from the Cyrillic script often...

    It's a letter from the Cyrillic script often translated as 'p' but it looks more like an 'n' with a flat top or the symbol for pi
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    Guinness isn't my first choice either but it was...

    Guinness isn't my first choice either but it was a time before you had micro breweries so it was either Guinness or one of the mega breweries. I've met two people off Ampage but I haven't been back...
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    It was great thanks, (what little I saw of it) I...

    It was great thanks, (what little I saw of it) I was working at Lawrence Livermore and only got out at weekends. I enjoyed walking over the Bay Bridge and driving up and down the coast road (highway...
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    Did you get to the east coast Chuck? I've been...

    Did you get to the east coast Chuck?
    I've been to both coasts and I live in the UK :)
  27. I think that's correct. Perhaps it would be...

    I think that's correct. Perhaps it would be better to start again from the beginning as a lot of what has gone on above is confusing?

    To start I'd remove FS4 and measure the transformer voltage...
  28. Must be a Lindstrom "feature" as mine are exactly...

    Must be a Lindstrom "feature" as mine are exactly the same. They don't have a retainer but are small enough to allow me to trap the cut off ends with my first finger.
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