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1AD4 (or russian subminiature) - OPA627 - BUF634 Headphone Amplifier for 32R and 300R Headphones

post #1 of 9
Thread Starter 

I am starting the schematics with the 1AD4: +60VDC with 1mA CCS (LT3092) for 2Vpp/32Vpp.

 

More coming soon...

 

Any suggestions or comments?

 

post #2 of 9

Just can't see enough of your schematic to comment really, the text is tiny and you can't blow it up.

 

w

post #3 of 9
Thread Starter 
1AD4-AMP_SCH.pdf 22k .pdf file

 

I need comments before starting layout, thanks.

post #4 of 9
Quote:
Originally Posted by jpaul64 View Post

LT3092

A couple of transistors will work as well, or better, and will cost 1/100th as much.
post #5 of 9
Thread Starter 

Do you have try the LT3092?

 

The BUF634 can also be replaced by transistors (see TubeCAD article and other stuff on the web).

 

I will try the LT3092 to build my own opinion.

 

I´m working on a small portable LiFePO4 power solution with an acceptable running time: 3 different supplies, the high voltage for the tube (2mA), the symetrical supply for the OPAMP (a few 100mA for 32R) and the supply for the heather (200mA). Today brainstorming on the concept but for the moment too much compromise in my design.
 

post #6 of 9

What is V111 MMA/0R0 zener?

 

What is N111 NE?

 

You have +3V connected to BAT-.

 

You have +60V DC connected to GND.

 

Your schematic is incomprehensible.

 

Your ideas are disorganized.

 

You have wasted my time.

 

w

post #7 of 9
Thread Starter 

sorry Wakabi!

 

For all the other:

- I will connect only +60VDC (text in red) and not the max. possible plate voltage of the 1AD4 for the desired voltage swing of 32V and a constant current of 1mA: for Wakabi, + at X111-1 and - at X111-2,

- therefore I need only 2 LT3092: N111 ist NE Not Equipped and bypassed by an 0R resistor (MMA or MINIMELF will fit SOD80C V111),

- the regulator will accept up the +45VDC but I will connect only one lithium battery: for Wakabi, + at X3-1 and - at X3-2, oups, perhaps a schottky on the plus pole? What do you mean Wakabi?

 

The blue values are the max. values, the red one for my first tests.

 

For the tests: +60VDC and 2 CCS in serie (experimentation needed with R113 - R116) for the plate; +3VDC lithium supply and DC/DC for +1,25VDC for the heating; BUF634 powered bei +/-18VDC.
 

post #8 of 9
Thread Starter 

I found a constant current source for 0,335€ in SOT353 package: +75VDC max@50mA max only only Rset resistor, the NXP PSSI2021SAY.

 

What do you think about this component?

post #9 of 9

Nothing wrong with this component, but not everybody needs surface mount, very small etc., never heard of it. 75V but only 50mA. Better in many ways to design with components people already have, e.g I have 200 each 2N3904 & 2N3906 @ $0.03, so if 30V is enough, I reach for these and I get <200mA.

 

Look here:- http://stores.ebay.com/Tayda2009

 

If you use components from this site, so common and cheap to make, not going to be a forgery, many people have them, you can get them easily, cheap, pretty quick, keep some in your drawer, try it out on a breadboard, don't care if it blows up, people don't have to look in a datasheet to understand your circuit. No?

 

w


Edited by wakibaki - 10/8/12 at 12:20pm
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