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Analogue adder circuit

F

Fred Bartoli

Jan 1, 1970
0
Jan Panteltje a écrit :
2 resistors.

That one will also divide by 2 for free.

If the OP really wants an adder he'll need one opamp and 2 Rs more.
 
J

Jan Panteltje

Jan 1, 1970
0
Jan Panteltje a écrit :

That one will also divide by 2 for free.

If the OP really wants an adder he'll need one opamp and 2 Rs more.

Depends, if he feeds the 2 R into a low impedance point he adds current
just fine without dividing.
It is all ration and error allowed.

1M and 1M into your uA meter (1k impedance perhaps) adds with .1% error.
 
J

Joerg

Jan 1, 1970
0
Fred said:
Jan Panteltje a écrit :



That one will also divide by 2 for free.

If the OP really wants an adder he'll need one opamp and 2 Rs more.

IN+ to GND, the 2 Rs from input sources to IN-, one more R from there to
OUT. Saves 1 R or about $0.008 fully burdened :)

Ok, it also inverts.
 
J

Joel Kolstad

Jan 1, 1970
0
Joerg said:
IN+ to GND, the 2 Rs from input sources to IN-, one more R from there to
OUT. Saves 1 R or about $0.008 fully burdened :)

I bet you build your instrumentation amplifiers using the two op-amp
approach rather than the better-known three op-amp approach too, right? :)
 
J

Joerg

Jan 1, 1970
0
Joel said:
I bet you build your instrumentation amplifiers using the two op-amp
approach rather than the better-known three op-amp approach too, right? :)
Nope, with the two-transistors-glued-together approach :)))
 
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