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Solid state rectifier question
Posted: Wed 04/04/12 2:43 pm
by lespaulblues
I'm just putting the 36watt together using the phat ass rectifier layout.
Is the load resistor the 220k going from the first side of the + on the
can cap to ground?
What determines the resistor value?
What sort of rectified voltage should i be getting for the b+.
Thanks
Re: Solid state rectifier question
Posted: Wed 04/04/12 3:19 pm
by rock_mumbles
lespaulblues wrote:
...
Is the load resistor the 220k going from the first side of the + on the
can cap to ground?
...
That sounds like the power supply bleed resistor ... how about a link to the schematic you are referring to ...
Posted: Thu 04/05/12 3:43 am
by Pressed_Rat
I guess you are referring to Scott Rubel's Phat Ass 16 schematic? Yes, that is a bleeder resistor, used to bleed down the power supply filter caps when the amp is shut off. I think 1/2 watt is sufficient; typical practice is to use 1/2 watt unless otherwise indicated. Won't hurt anything to leave it out, but you'd better be careful poking around the chassis. Actually it's best to be careful anyway.
Re: Solid state rectifier question
Posted: Thu 04/05/12 5:29 am
by guitar-rocker
lespaulblues wrote:I'm just putting the 36watt together using the phat ass rectifier layout.
Is the load resistor the 220k going from the first side of the + on the
can cap to ground?
What determines the resistor value?
What sort of rectified voltage should i be getting for the b+.
Thanks
As mentioned, the 220K is the bleeder resistor. Were you actually inquiring about a sag resistor, because on the Phat Ass, there was not one used.
Posted: Thu 04/05/12 2:37 pm
by lespaulblues
No i wasn't going to use a sag resistor.
Any idea what dc voltage i should get with the 36watt mains transformer
with 240v mains?
I haven't done solid state before,that's why i'm asking.
Thanks.
Posted: Fri 04/06/12 5:45 am
by scottva59
I dug up and old schem. of a 36w version I did with the GDS xfmr set with voltages noted.
http://farm8.staticflickr.com/7200/7050 ... 9239_b.jpg
Here I did use a sag cuz I was trying to get the B+ down a little. Can't trust my memory but I think with out the sag I was getting just over 360v using 120 mains. Nothing stopping you from experimenting with or without a sag and trying different values, season to taste. Hope this helps. The as built version of this amp had a great bark!
Scott
Posted: Fri 04/06/12 2:23 pm
by sub
I think a 2W resistor would be better here.
If B+ is 360V then: (360x360)/220000=0,59W.
Posted: Fri 04/06/12 2:56 pm
by scottva59
Yep, 2W for bleeder.
Posted: Sat 04/07/12 10:47 am
by zaphod_phil
Those were actually 6V6s in the power stage, and not EL84s, right?
Posted: Sat 04/07/12 12:31 pm
by scottva59
That version was a quad of EL84s - Rocket inspired (cloned) output power stage. I've never tried a quad of 6V6s.