AOUT_LC_Unipolar

[Phatline]

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:

 

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)

...

 

 

Edited July 21, 2015 by Phatline

[latigid on]

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.

[Phatline]

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...

[latigid on]

You could try the MCP6002 for a cheap trial. In the end it still makes sense to use a bipolar PSU I think.

[Phatline]

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  ...

[latigid on]

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+?

Edited July 21, 2015 by latigid on

[Phatline]

thx for the info, i finally have done it with a simple bc337 and a 680ohm resistor, finally unipolar ;-)

 

Edited July 21, 2015 by Phatline