http://ucapps.de/mbhp/mbhp_aout_lc.pdf >> This Circuit is made for a Bipolar-PowerSupply
but how looks a unipolar powered Version?
the comes out that a simple bc337 can do the job (idea from the core backlight shematic ;-) )
see this:
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one problem that i have to solve is the logaritmic… a linear scale with all the same 10k resistors in a network, dont sound very accourate…
How to handle the unused side of the OP-AMP?
Whats about the Offset-section? > No -15V there… so clamp to ground?
Is there something else to change.
how to make a logaritmic variant?
i have built the circuit above on vectorboard, and it act a bit strange when switching between DOUT-Pin 0 and 1 -pin 0 make louder sound then 1 >>> Pin 2-7 acting normal (Volume gets higher)
0>1 (wrong)
1<2 (right)
2<3 (right)
3<4 (right)
4<5 (right)
…
If you want to use a single supply, choose a rail to rail op amp or bias the input (or just use a bipolar supply, this is a much better idea). The op amp won’t swing close enough to the PSU rails for it to be useful, i.e. you will have a constant DC offset.
what type of rail to rail op amp - is common? (so i can easy buy it by going to conrad, or to the local radio shop?)
i think it will end by building a bipolar supply, since it turned out that op amps are a own sience…
You could try the MCP6002 for a cheap trial. In the end it still makes sense to use a bipolar PSU I think.
thx…by the next order i have some MCP6002!..
whats about the unused Side of the TL72?
in the 606 i dont need -15V in there… but i thought of a MS20 filter on the master times bevore ,…and then i would need it again… but no 7915 @ home… arghlxwahh …
First option is to buy the single version (MCP6001). Next best is to wire the inverting input and output together with the non-inverting connected to a potential between the power rails (e.g. make a 1:1 divider with two resistors).
http://www.analog.com/media/en/rarely_asked_questions/RAQ_unused_op-amp.pdf
Btw, it looks like you’re trying to power your circuit through I2+?
thx for the info, i finally have done it with a simple bc337 and a 680ohm resistor, finally unipolar 
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