Search:

Type: Posts; User: Old Tele man; Keyword(s):

Page 1 of 18 1 2 3 4

Search: Search took 0.02 seconds.

  1. Replies
    27
    Views
    781

    The REASON for eqaul-sized "balancing resistors"...

    The REASON for eqaul-sized "balancing resistors" is to "EQUALLY" divide the voltage across the two caps at FULL/peak voltage and NOT during the initial "charge/pump" up when the voltages are smaller...
  2. Replies
    64
    Views
    1,877

    SINE-squared: 54093 COS-squared: 54094

    SINE-squared:
    54093

    COS-squared:
    54094
  3. Replies
    64
    Views
    1,877

    Actually, you are correct -- I mis-typed -- the...

    Actually, you are correct -- I mis-typed -- the Vg "value" should be 35Vg, derived from one-half of Vgg; ie: Vg = (70Vpp/2). Hopefully, I haven't made other such errors in my previous posts, for...
  4. Replies
    64
    Views
    1,877

    0.637 is AVG of fullwave rectified signal. ...

    0.637 is AVG of fullwave rectified signal.

    Because both ELECTRONICS engineers and ELECTRICAL engineers use the same physics principles and terminologies, people like National Semiconductor's Bob...
  5. Replies
    64
    Views
    1,877

    Regarding amplifiers, I repeat "...there is NO...

    Regarding amplifiers, I repeat "...there is NO such thing as RMS power...it's AVERAGE power."

    The Root-Mean-Square (RMS) mathematics simply converts the peak VOLT or AMP value of a sinusoid to...
  6. Replies
    64
    Views
    1,877

    That value is directly quoted from the GE/RCA...

    That value is directly quoted from the GE/RCA 6L6GC datasheets...worked great from them back in the hey-day of vacuum tubes.

    For example:

    Po ≈ (%)*(Zoo/4)*(gm*|-Vg|)^2

    Where GE/RCA Class-AB1...
  7. Replies
    64
    Views
    1,877

    Your assertion *IS* valid when Vg(rms) exactly...

    Your assertion *IS* valid when Vg(rms) exactly equals Vg(bias.dc), which rarely happens; typically Vgg/2 is "less than" Vg(dc) by a couple volts, just for "good measure," For example, see GE/RCA data...
  8. Replies
    64
    Views
    1,877

    ...and he (me) also later explains that the DC...

    ...and he (me) also later explains that the DC bias voltage is assumed to equal the AC(rms) driving signal for estimating Po from the schematic values of Zoo (OT), gm (power tube), and applied BIAS...
  9. Replies
    64
    Views
    1,877

    See this brief paper: ...

    See this brief paper: http://thermionic.info/mccaul/McCaul_PhaseInverterDriveVoltage_2008.pdf
  10. Good use for "past-useful-life" tubes...except...

    Good use for "past-useful-life" tubes...except those with "open" filaments (ha,ha)!
  11. Replies
    64
    Views
    1,877

    Class-AB1 PP amps do not conduct 360-degrees,...

    Class-AB1 PP amps do not conduct 360-degrees, only about 190-205-degrees, or more generally 'slightly more' than 50% of a FULL sinusoid, so referencing a 'pure' sinewave is only valid prior to the PI...
  12. Replies
    64
    Views
    1,877

    First, there is no such thing as WATT(RMS)! ...

    First, there is no such thing as WATT(RMS)!

    Why? Because RMS is just the mathematical-equivalency operation (0.707*pk) that's applied to the peak value of sinusoidal VOLTS and/or AMPS to convert...
  13. Replies
    64
    Views
    1,877

    No, as Vg is BIAS (DC voltage), not Vgg which is...

    No, as Vg is BIAS (DC voltage), not Vgg which is AC peak-to-peak, which I believe you are thinking about.
  14. Replies
    64
    Views
    1,877

    *IF* you're wanting to 'guess-ti-mate' an...

    *IF* you're wanting to 'guess-ti-mate' an approximate output power for a Class-AB push-pull amp by simply looking at its schematic, here's an equation:

    Po ≈ (%)*(Zoo/4)*(gm*Vg)^2

    where:
    Po =...
  15. Replies
    64
    Views
    1,877

    Just to add some more mud to the waters: AMPS and...

    Just to add some more mud to the waters: AMPS and SPKRS are (unfortunately) spec'd differently, for example, on many Fender schematics, it's 400Hz for bass amps and 1kHz for guitar.
  16. Replies
    64
    Views
    1,877

    Just remember, it's AVERAGE power in Watts, not...

    Just remember, it's AVERAGE power in Watts, not RMS power!

    Root-Mean-Square (RMS) is merely the mathematical conversion technique that's applied to sinusoidal VOLTAGE and CURRENT to derive their...
  17. Replies
    16
    Views
    655

    ..or, we could just slap on some TEMP-IT shipping...

    ..or, we could just slap on some TEMP-IT shipping stickies, which change colour when their temperature threshold is exceeded.
  18. Replies
    16
    Views
    655

    Also, always *inspect* the blown fuse link (clear...

    Also, always *inspect* the blown fuse link (clear glass body assumed): if it's *splattered* that indicates a sudden high current load, but if the link is just *sagged* and pulled-apart in the middle...
  19. Replies
    16
    Views
    655

    Nice article!

    Nice article!
  20. ...or, parallel another output tube with the...

    ...or, parallel another output tube with the original SE tube, but remember input drive (due to lower Z.in) will change.
  21. 2W is fine...plate should be catching 90-95% of...

    2W is fine...plate should be catching 90-95% of total (ie: cathode) current flow, so unless something else is wrong, screen current should be roughly 5-10% or less than plate current.
  22. Try inserting a 100 ohm resistor between the...

    Try inserting a 100 ohm resistor between the screen and plate and verify the hum isn't coming through a bad/weak filter capacitor.
  23. Analog analogy: think about "slew-rate" of...

    Analog analogy: think about "slew-rate" of signals through capacitors.
  24. Pushed" OT's do not handle squarewaves (grossly...

    Pushed" OT's do not handle squarewaves (grossly over-driven sinewaves) anywhere as they do for true sinusoidal waves, which is what they're designed to handle. Note that a true squarewave/pulse...
  25. On that Gretsch_G6156 schematic, did you notice...

    On that Gretsch_G6156 schematic, did you notice that the right-half triode of the 6SC7 has NO cathode connection -- nothing connecting the two cathodes together. Obviously a drawing error, or the amp...
  26. Interesting, but I wonder about lack of EMI...

    Interesting, but I wonder about lack of EMI shielding with that plastic case since the old (original) models had metal case which served as shield against EMI.
  27. Replies
    14
    Views
    1,585

    I'll guess the packaging co$ts more than the...

    I'll guess the packaging co$ts more than the actual tube/valve does.
  28. Replies
    9
    Views
    846

    A single, common, cathode resistor "smooths-out"...

    A single, common, cathode resistor "smooths-out" possible conduction differences between the banked tubes (think "mean" value here), while separate cathode resistors can be individually...
Results 1 to 28 of 500
Page 1 of 18 1 2 3 4