Tube DIY Asylum

Any idea how they bias up?

76.90.100.230

Tre'

In Reply to: RE: CASCODE... posted by PakProtector on April 20, 2024 at 17:54:43

The 10m45s have this nice chart on the datasheet but I don't see that with the DN3545N3.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

Follow Ups:

sure... :) - PakProtector 01:32:17 04/24/24 (3)
The datasheet linked through the digikey site has two sets of plate curves. the more detailed set has D-S voltage from 0-10V. It is not the bias R sort, but just as you'd use a set of screen-grid-less pentode curves to determine bias R, you should use those...

These are MOSFET's, not dedicated current regulators, yes?

Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
- RE: sure... :) - Tre' 11:06:36 04/24/24 (2)
  Yes, MosFets
  
  sorry for being dense but how does this help me?
  
  Tre'
  Have Fun and Enjoy the Music
  "Still Working the Problem"
  - RE: sure... :) - PakProtector 01:40:18 04/25/24 (1)
    We are hunting for a current setting resistor, yes? Whilst the 3545 is running beneath a 10M45, right?
    
    So...draw a vertical line at 3V.
    
    Then join me in the guess that we want about 1.7V for operation at 20-30 mA.
    
    Apply Ohm's Law to determine the resistance required to deliver 1.7V at this idle current. Unless you wish to run 50 mA...in which case, note there is a gate line at that current( the -1.5V lowest one ).
    
    Since the 1.7 is a guess/interpolation be prepared to adjust this value a bit. I suggest some battery bias to bring the effective bias voltage up to ~12 so most of the resistance is dedicated to covering the battery's extra voltage.
    
    Douglas
    Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
    - RE: sure... :) - Tre' 11:44:12 04/25/24 (0)
      Yes and yes.
      
      I get it but I'm doing 11 ma. for my drivers and 10ma for the second stage of my phono preamp and 2.3ma for the first stage of my phono preamp.
      
      I just used trim pots to find what value Rset resistance I needed in each instance. It's all working fine now. Thanks.
      
      Tre'
      Have Fun and Enjoy the Music
      "Still Working the Problem"

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