Aleph 3? Project.

[Zen Mod]

full wave with two diodes

it needs CT

 

[Zoef]

Took some time to think and read. Here is a picture of the transformer . (I got two 15v transformers. One is 50va the other 80va. Not decided wich one to use. Both are same make so have same lay-out . Picture is of the 50va)

An externally hosted image should be here but it was not working when we last tested it.

So if i tie blue and yellow together the voltage doubles.

If i connect blue and yellow to ground it creates a center tap and the voltage is back to 15v again?

If this is correct, do i connect it to gnd of the board or should i make a star like ground on the chassis and then connect this to gnd on the board. the "building guide" (some crap paper) says gnd on the board needs to go to the chassis/front plate because the volume pot is there.

Thank you zenmod. Do i directly connect it to the gnd on the board or like i described from the crappy manual

 

[Chamberman]

So if i tie blue and yellow together the voltage doubles.

If i connect blue and yellow to ground it creates a center tap and the voltage is back to 15v again?

If this is correct, do i connect it to gnd of the board or should i make a star like ground on the chassis and then connect this to gnd on the board. the "building guide" (some crap paper) says gnd on the board needs to go to the chassis/front plate because the volume pot is there.

Yes the VAC will be double if measured from Red to Grey. But you are concerned about what the LM7812 will see, which will be about 19 - 20 VDC when rectified. Connect Blue to Yellow and tie them to the center ground hole. Red and Grey are tied to the 15VAC inputs. Use the 50VA, it is plenty large enough.

 

[AudioSan]

Here you go audiosan

An externally hosted image should be here but it was not working when we last tested it.

Edit: It is for the volume control. It uses relais.

now it makes sense so yellow and blue to GND on the board, red and grey to the two 15V inputs.

 

[Zoef]

Thank you all!
I have gone a "little" off topic with my aleph l questions.
So back to the aleph 3. Included a small picture of one of the amp boards.

An externally hosted image should be here but it was not working when we last tested it.

It says irf244. But isn't a irf244 a T0-220 device? So does this have to be a irfp244?

 

[AudioSan]

irfp244 is TO-247. irfp244 is 250V 15A 280mOhm device, while irfp240 is 200V 20A 180mOhm device.

 

[Zoef]

Yes, but that is not the question. If you see the picture it says irf , should this be irfp

 

[AudioSan]

you will most likely not find irf240/244 parts anymore just use irfp240PBF.

 

[Zoef]

Ok, got some 244's ok to use?or are 240's better. I got no interest in future upgrading the amp to higher wattage. My speakers are very sensitive. So no need for more.

Edit: do they need matching?

 

[AudioSan]

if you have irfp244 you can use them. just remember to get them matched if they're not already.

 

[Zoef]

Ok, i have some that are matched but not sure the right way. On the package it says matched

Edit:got them on ebay smaller 8mv

 

[AudioSan]

then i would buy som matched 240's from h_a.

 

[Zoef]

Guys, wich make/model would be the best for a 4.7uF mkp in the power supply?

 

[AudioSan]

i use wima mks.

 

[6L6]

I don't bother to use a bypass cap in the PSU. Neither do the factory amps.

 

[Zen Mod]

me neither

I'm just using 50uF motor runs as final caps

 

[Zoef]

For the 22000uf's , any tips on what brand/model to buy?

 

[Zen Mod]

what you have at your preferred vendor ?

 

[6L6]

Panasonic, Nichicon, Rubycon, Cornell-Dublier, etc... With your power supply PCB you need 10mm lead spacing and a max diameter of (I think) 35mm.

 

[Zoef]

Yes max 35mm .

An externally hosted image should be here but it was not working when we last tested it.