Re: 1 million amp gone astray?

Discussion in 'Computer Information' started by Paul, Dec 1, 2010.

1. PaulGuest

Robert Baer wrote:
> This is what i just made and measured.
> What the heck is going on?
> Where did the current go?
> Input section is OK; current from voltage source X shows as an analog
> voltage at point Y and computes correctly.
> But the summing junction Z value implies a specific current from Y to
> Z that is not equal to that from Z to the -15V rail.
> Have a capacitor from Z to ground to prevent oscillation.
>
> +------------------------------------------
> | 100K |
> | +---/\/\--+ |
> | 150K | 2(\ | Y |
> X--+--/\/\---+--( \ ---+---+ |
> +--( / 1 | |
> | 3(/ \ |
> G 100K / 100K |
> \ 6(\ |
> | G--/\/---( \ -+
> Z +-----------( / 7
> | 5(/
> OPA2277 \
> / 150K
> \ Meas: X = 3.0V
> | Y = 2.0V (so far so good)
> V Z = 0.0V (nonsequitor)
> +15

You should try out the analog simulator that linear.com
used to offer (SwitcherCAD), and then you can do the whole
circuit on the computer. If any voltages or currents are infinite,
there is no crater left in your living room. You'd use
an "ideal" opamp, as there is no need to simulate with
a more realistic model.

(LTSpice - apparently a name change from the old SwitcherCAD)