OTL Asylum

Location of the relay for time dela

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(A)

Hello.
Now I'm building 6c33c OTL amplifier.
Which is the best location of relay for time delay of the followings?
1) primary of the power transformer for B+
2) just before bridge diode
3) next to bridge diode
Any opinion will be greatly appreciated.
Thank you.

Follow Ups:

Re: Location of the relay for time dela - klaus 07:49:56 11/13/04 (4)
Between fuse and primary, no doubt.
- Re: Location of the relay for time - alex 19:01:24 11/13/04 (3)
  Thanks a lot!
  But according to the most schematics that I have ever seen,
  relay is put between bridge diode and first capacitor.
  (Not in the primary at all)
  Why is it? Pleas see this.
  http://www.audiodesignguide.com/my/OTL_version_82_ocl.gif
  For my Otl, it has 2 transformers too.
  One is for all B+ and C+, the other is for only heaters!
  Best Regards.
  - Re: Location of the relay for time - klaus 02:39:43 11/14/04 (2)
    One transformer for all B+ sources - indeed, requires switch in the secondary. It's not the safest arrangement - relay contacts will wear out faster than they would in primary circuit.
    Two safety tips for longer life of a switch:
    1. Place switch in low current path. Bridge-to-first-cap is actually the highest current path in the circuit.
    2. Place switch in AC, not DC current path.
    A completely different approach is redesigning bias supplies. Instead of slowly falling from 0V to required negative -Vg, make a circuit that goes down to -150V on the first AC half-wave, practically instantly, then slowly rises to -Vg. This eliminates the need for B+ delay. It's quite safe in Circlotron output stage.
    P.S. DIY designs usually aren't examples of safe engineering :) especially the Futterman varieties.
    PP.SS. Take a closer look at diode bridges in Ciuffoli's bias supply - see what I mean? :)))
    - Re: Location of the relay for time - alex 02:58:36 11/15/04 (1)
      Thank you.
      " Take a closer look at diode bridges in Ciuffoli's bias supply - see what I mean? "
      Would you give me a hint?
      Bridge Diode + 47uF + 20K + 220uF + (22k+39k)
      I think 20k is too high.
      47uF 350V???
      - Re: Location of the relay for time - klaus 03:50:30 11/15/04 (0)
        
        In Reply to: Re: Location of the relay for time posted by alex on November 15, 2004 at 02:58:36:
        
        Diodes in the middle bridge on the right side are connected in short circuit.

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