diyAB Amp The "Honey Badger" build thread

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thompsontechs

thompsontechs

Member
Joined 2019
thompsontechs said:
Okay guys, just went back to work and my brain is cooked, need a sanity check please.


Looking at the snubber for a 115v trans with the sec at 45v. the standard .15uF cap and a R of 954.



I'm trying to make sure I have enough power rating on R954 to make sure it has a long and happy life. I think I remember Mark, or someone saying you want 2-3 times the max to ensure good life and service.



So, with those numbers I got about 47.2mA as the wattage through the resistor. Can someone check me on this... I have a 1/4 and 1/2 watt Rs and was just going to use the 1/2 to have a large margin, but not sure my addled brain has the math right.


Thnaks


JT
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Nobody willing to check my math? :eek:
 
A

andrensairr

Member
Joined 2016
thompsontechs said:
Okay guys, just went back to work and my brain is cooked, need a sanity check please.


Looking at the snubber for a 115v trans with the sec at 45v. the standard .15uF cap and a R of 954.



I'm trying to make sure I have enough power rating on R954 to make sure it has a long and happy life. I think I remember Mark, or someone saying you want 2-3 times the max to ensure good life and service.



So, with those numbers I got about 47.2mA as the wattage through the resistor. Can someone check me on this... I have a 1/4 and 1/2 watt Rs and was just going to use the 1/2 to have a large margin, but not sure my addled brain has the math right.


Thnaks


JT
Click to expand...


Paragraph 6 on page 7 of Mark's article details the selection of Rs. The question I have is, how did you arrive at 47.2mA for current through Rs? It seems a bit high - unless by R954 you mean 0.954 ohms - that would be atypically small, I think.
 
H

hpasternack

Member
Joined 2002
Begging your pardon, and apologies if it's a FAQ, I have a pair of these boards that I never built up. I am curious if it's even possible to source semiconductors anymore. I know the question of substitutes has come up in this thread occasionally but I haven't tried yet to read all the posts. Has anyone published a viable BOM for 2021?

It's really quite discouraging to come back to solid-state after ten years and discover all the small-signal devices are out of stock.

Alternatively, if someone wants a pair of boards...

Thanks.

-Henry
 
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AudioSan

Member
Joined 2009
hpasternack said:
Interesting. There seem to be different documents out there. Definitely the supply of THT semiconductors is shrinking. The other day I was looking through the list of transistor options in the build guide and everything was coming up obsolete and out of stock. I will try again. Thanks.
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I found every transistor exept SS9014, 2SA1381 and 2SC3503 at Mouser just now. SS9014 can be substituded by MPSA18. 2SA1381 by MJE350 and 2SC3503 by MJE340.

there is also other substitudes out there.
 
H

hpasternack

Member
Joined 2002
Thanks very much. I've been preoccupied with tubes for a long time, and was surprised to find how the semiconductor parts supply landscape has changed. In my mind, college doesn't seem that long ago, but I suppose it makes sense that bread-and-butter transistors from forty years ago (incredible!) are no longer in production.
 
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