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ALWSRs completion. Mounting, isolation and transformer choice.

chrisn

pfm Member
Can you help me complete this please:-

1. The conventional way to mount these (four ALWs) would be to the base of the case using insulated pads and paste which is really fiddly (also I don't have any). Can I use anything else like sellotape, even a single sheet of insulator would be better than individual mics pads.
https://www.dropbox.com/s/itc4qzshf9fv28q/P1010221.JPG?dl=0
2. How much heatsinking do they need? They are 24V regulators supplied with 39V DC. Could I use individual heatsinks uninsulated? I appreciate they will be live.
https://www.dropbox.com/s/prz4273alfckbrr/P1010220.JPG?dl=0
3. I have a choice of 120Va and 300Va transformers with dual secondaries. Which?

Thanks in advance
 
Use whichever transformer is easier; I’d go with the 120VA, and splut the reservoir cap into two with a small resistor between c-r-c filter ahead of the regulator. The values can be quite small (2200uf -2.2ohm-2200uf, ballpark; its not critical +/- 100% will be fine too!)
 
Chris


If you're powering a 72, you would only require 2 super-regs, if you're putting the regs in the power supply.

With a voltage drop of 39 to 24 you could put a capacitor multiplier before the SR. They are very simple to make, film caps, resistors and a transistor. There will be diagrams somewhere on the forum.

With regards to the transformer. I recall Andy saying the AWSR's work better with a large transformer.

I mount my AWSR on these (or something similar).

https://i.ebayimg.com/images/i/121878135631-0-1/s-l1000.jpg

If you look closely at my avatar you might be able to spot 6 x AWSR in my 62.
 
I'd only spare so much voltage only for testing purposes. Having a pre regulator (or VBE if you prefer) I would not use a multiplier before it. I'd use that money to buy an appropriate transformer which don't have to be that big (if 250mA is needed), a 60VA will suffice.
I'm probably bias against heat because of hotter climate than north European countries plus currently most of my small signal circuits (pre, dac, phono) are class-A so I'd go for efficiency.
 


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