Phatline Posted July 21, 2015 Report Share Posted July 21, 2015 (edited) 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 Quote Link to comment Share on other sites More sharing options...
latigid on Posted July 21, 2015 Report Share Posted July 21, 2015 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. Quote Link to comment Share on other sites More sharing options...
Phatline Posted July 21, 2015 Author Report Share Posted July 21, 2015 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... Quote Link to comment Share on other sites More sharing options...
latigid on Posted July 21, 2015 Report Share Posted July 21, 2015 You could try the MCP6002 for a cheap trial. In the end it still makes sense to use a bipolar PSU I think. Quote Link to comment Share on other sites More sharing options...
Phatline Posted July 21, 2015 Author Report Share Posted July 21, 2015 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 ... Quote Link to comment Share on other sites More sharing options...
latigid on Posted July 21, 2015 Report Share Posted July 21, 2015 (edited) 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 Quote Link to comment Share on other sites More sharing options...
Phatline Posted July 21, 2015 Author Report Share Posted July 21, 2015 (edited) 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 Quote Link to comment Share on other sites More sharing options...
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