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OLD THREAD DAC End by Andrea Ciuffoli

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#1,441
housing said:
CustomHT,

I don't have the regulator board, I have the HV shunt supply PCBs only.

Don't populate the 4 HV rectifiers and the 4 snubber capacitors on your board. Instead solder the center tap to a plate-thru' via connected to the -ve pole of C5 (100uF/450V) and the rectified HV to a plate-thru' via connected to the +ve pole of C5.

In such case, you can use the full 200mA capacity of the transformer.
Click to expand...
ok, I will try this.. What exactly is ment "to a plate-thru' via"?
Do I simply soldier the leads to the -ve and +ve pole's of C5 as suggested?
Cheers
 
#1,442
I read the Dac End 2 webpage, saw where he was experimenting with filters. If you are having trouble with no filter, one option is to increase the miller effect of the tube by adding a small cap from the grid to the plate, its capacitance is multiplied by mu and is a 2nd order low pass filter.
 
#1,444
housing said:
CustomHT,

I don't have the regulator board, I have the HV shunt supply PCBs only.

Don't populate the 4 HV rectifiers and the 4 snubber capacitors on your board. Instead solder the center tap to a plate-thru' via connected to the -ve pole of C5 (100uF/450V) and the rectified HV to a plate-thru' via connected to the +ve pole of C5.

In such case, you can use the full 200mA capacity of the transformer.
Click to expand...

CustomHT,

Don't get confuse. What housing meant was you already rectified the ac voltage outside the board and the rectified voltage which is DC is connected directly to the + and - leads of the C5.

I think Apelizzo is using the same transformer as we are, so why not try just the green and orange wire?
 

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#1,447
I finally completed the Salas shunt regulator!
I tested with 3 x 9V ac transformer. Is very stable but I can not adjust
less than +/-5.72V for AD1865. R1, R7 = 33R 2W heat! Which should be the maximum voltage?
For CS8414 I managed to adjust minimum 5.28V. R13 = 22R. Is OK?
 
#1,451
Last edited:
#1,453
fredlock said:
CustomHT,

Don't get confuse. What housing meant was you already rectified the ac voltage outside the board and the rectified voltage which is DC is connected directly to the + and - leads of the C5.

I think Apelizzo is using the same transformer as we are, so why not try just the green and orange wire?
Click to expand...

Ok that makes sence. Basically the board is made so I could have just used mains voltage connected straight to the 200-250V connection, but since I am using the output from the trannie I bypass the rectifier section..

I will try connecting the green and orange wire to the + and - wire of C5. And post results..
 
#1,454
CustomHT said:
Ok that makes sence. Basically the board is made so I could have just used mains voltage connected straight to the 200-250V connection, but since I am using the output from the trannie I bypass the rectifier section..

I will try connecting the green and orange wire to the + and - wire of C5. And post results..
Click to expand...

😱 Don't connect the green and orange wire directly to C5. It needs to go thru a diode first for rectification and then connect it to C5. If you do this, then wear a safety glass first before you turn on. 😀
 
#1,459
I think I am over project'd right now and would like to sell my boards if someone is interested.
I have the 4 boards, plus the Analog 1865N-K chip from Mikel-Ann's GB. Additionally I have a few caps for the salas board to throw in.
I am looking for a decent offer on this. PM if interested.
 
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