re public domain circuits in commercial applications in article apr wuecl wustl edu dp cec wustl edu david prutchi writes can circuits found in electronics magazines with no patent disclaimer be used legally as subcircuits of a commercial unit there are two issues here copyright and patent the magazine article s contents are copyrighted and may not be reproduced translated etc without the copyright holder s permission however this does not cover the ideas expressed only the form of expression copying their circuit diagram or pc board pattern is copyright infringement but it s unlikely that they could stretch copyright far enough to claim that the circuit design itself is copyrighted so long as you draw your own diagrams and lay out your own boards copyright shouldn t be an issue patents are different the author does not have to give you any warning that the design is covered by patent although it would be sensible for him to do so in fact it s possible that he was infringing on someone else s patent without realizing it ignorance of the patented status is not a defence against infringement although it might reduce the damages a court would award however unless there was something seriously novel about the circuit almost certainly it is obvious to one skilled in the art and therefore unpatentable routine engineering is not patentable patents in theory cover only inventions ideas that are genuinely new caution i am not a lawyer consulting a professional would be wise if significant amounts of money are at stake all work is one man s work henry spencer u of toronto zoology kipling henry zoo toronto edu utzoo henry
