Poor Serbian Man Optical Volume Control

[Zen Mod]

then just replace all small BC bjts

easiest way ;

check each LDR's LED with diode test on your DMM

I hope you didn't burn any

 

[José Humberto]

Fortunately the LDR are alls well.
I´ll try again this evening.
Take a good day.

 

[José Humberto]

Hello friends:
I read again the cookbook and after replaced ZD3 and R2 for a potentiometer and get then 15V, jumping R2 the intensity remained high (is a botched job that I hope to resolve more later). I´d like put measures in schematics but I don´t know do it.
The resulting measures take alls to gnd with jmp 01 and 02 open and main potentiometer at twelve o´clock, are:
Output transformers: 22,62V
PSU rail 15V
Top of the LED1, 4,11V
Between LED1 and VR1: 2,33V
VR1
Leg 1 = 0V
Leg 2 = 2,33V
Leg 3 = 0V
Bottom of jumper 01: 5,75V
Bottom of jumper 02: 1,41V
Top of jumper 01 (from LDR): 13,5V
Top of jumper 02 (from LDR): 14,1V
Between R5 and Q4: 4,1V SUSPECT!
Between R6 and Q5: 2,14v
Current acroos jumper 01 0mA
Current across jumper 02 25mA DANGEROUS!
At this time don´t replaced any parts, I think is better the experts look first.
Any suggestion besides replace the bcs?

 

[José Humberto]

Finally I chose another pcb that I had at home and I started again carefully.
I detected two mistake choosen parts in the old.
The new PCB works great, but I struggled to match the channels. I'll go to a friend's house with scope when I get appropriate 2M2 potentiometers.
The important thing is that the sound is really good. Now it's time to test LS buffer, buffer-LS-buffer and find my favorite. Then I´d like put remote control, another battle.
Thanks to SP and ZM. The work is really fantastic.
Best regards
P.d:
One LDR have the dot in the other side.

 

[Zen Mod]

......
One LDR have the dot in the other side.

bummer

PS - sorry , I didn't got that post from 2-nd december

 

[spavleski]

Hi Jose. Enjoy !

You don't need 2M2 potenciometers...

See

http://www.diyaudio.com/forums/diyaudio-com-articles/168796-poor-serbian-mans-optical-attenuator.html

especialy below part that explain this picture:

http://www.diyaudio.com/forums/images/articles/opticalattenuator/original/18.jpg

 

[José Humberto]

PS - sorry , I didn't got that post from 2-nd december[/QUOTE]


Do not worry, you work a lot for the DIYer for to have to apologizing, and then, reading my English.

 

[José Humberto]

Buffer PSU

¡Happy new year!
I´d like built in my own board (matrix dots) this PSU for a headphone amp but I´d like too can adjust the voltage between +/- 9 V to +/- 15 V or so. for test sound. ¿Can I put trimers in any place of circuit? This way is very confortable.
Thanks a lot.

 

[Zen Mod]

Jose

HNY to you

which PSU ? shunt , for buffer stage ?

you need to tell me which headphone amps schm , so I can make needed changes , that circuit suit your needs

 

[José Humberto]

Excuse me for don´t explaind well.
The PSU of PCB 02. Is a c-moy without battery PSU.
Thank you for your quick reply.

 

[José Humberto]

Off topic:
This is for my son. Now I´m working on mine.
The cover is brushed aluminum.

 

[José Humberto]

And another one.

 

[Zen Mod]

you made proper bipolar supply , as I can see from pics ?

so - 2x18Vac/6VA xformer , and you need 2x9Vdc up to ......... we'll see what max can be

tomorrow , please

 

[José Humberto]

Fantastic!
I built the psu from twistd pear audio, run ok, but I´d like test another thing. The chip can use +/-5 to +/- 18V therefore I need the trimers.

 

[LuisMCP]

And another one.

My God!

a chassis that weighs a ton!

 

[José Humberto]

Isn´t too heavy, is wood and aluminum. My new toy, RCA AR-88D, weight an egg.
Best regards

 

[prasimix]

Hi, does anyone maybe have some matched LDRs (NSL-32SR3) that are for sale? I'd like to buy two pairs if that is enough for unbalanced version of Zen Mod's volume control.

Thanks.

 

[AndrewT]

Uriah sells matched pairs and sets.

 

[prasimix]

Uriahp or Uriah Heep?

 

[palmito]

Uriahp or Uriah Heep?

It's udailey, but check this statement from him http://www.diyaudio.com/forums/grou...mfortable-passive-pre-amp-51.html#post3629586 .