Hi, how do I connect 4 of LM358 with -9V if I use a Parallax wall-mount supply 9V? I suppose that 8 is connected with Vin of Board of Education. Thank you in advance. MichelB
There is no negative supply voltage available. The LM358 can be operated with only a positive supply. Connect pin 8 to Vin and pin 4 to ground (Vss). The datasheet (from National Semiconductor) has several examples of "single-ended" use (with only a positive supply). Remember that your 9V wall wart may be noisy and you may need some extra filtering for the LM358. Try it first. You can always add a 220uF to 470uF 16V electrolytic across the 9V supply near the LM358 if you need it. Don't forget a 0.1uF ceramic capacitor close to the LM358 across the supply leads.
The LM358 can be used with a dual-supply system…the part from National up to +/- 16V, but I think the OP is referring to Andy’s article on the subject at the following link. The answer to your question is that using a wall-adapter you really can’t generate the -9V. You would need a dual-supply referencing the same ground for this to work.
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Chris Savage
Parallax Engineering