EveryCircuit
Powering up...
Circuit
Public
Private
Unlisted
Save

Cannot find solution - opamp current source transistor matcher

@eeveleigh
11 years ago
https://everycircuit.com/circuit/4733134065106944
The circuit is supposed to pull about 100 microamps through the top NPN transistor through the 6.8k resistor. If you know opamps its very easy to see this assuming an ideal opamp. Opamp imposes 5V across 51k resistor where the majority of the current must be drawn through the collector of the bottom NPN and consequently also through the top NPN. I am wondering why a circuit that is so easy to be solved by "inspection" cannot be solved by EveryCircuit. Anyone have any ideas? Well it turns out that you have to put switches across the collector and emitter of each transistor to get the simulation started up. Once the simulation is started you open the switches to see the actual circuit.
Comments
Post