Integrator
An Integrator is an elementary building block of an analog computer which carries out an Integration in time, as in c = integral_0^t integrand(t') dt'. The Analog Thing ships five integrators. That menas you can compute five integrals in a circuit.
Integration in analog computing typically falls back on continously charging a capacity (condensator). The only difference between an integrator and a summer is this very capacity in the feedback channel instead of a simple resistance. Therefore, all integrators are also summing their inputs. For more details, please refer to Analog computing literature.
Basic Usage of an Integrator on The Analog Thing
- Circles represent inputs, triangles outputs
- Analog integrators always sum their inputs. That is, if you have a sum under your integral, you can save a single summer before the integrator. Otherwise, just put your integrand into the upper left input labeled with
1. - There are two output slots. Just use one of them as you like.
- The
ICslot stands for initial conditions. It is an input where you have to provide suitable initial conditions. As shorthands,-1and+1are right to the hand. If this slot is left empty,0is taken as initial condition. - For the time being, ignore the slots
SJandSLOW.
Attention: Make sure the sum of your inputs does not exceed the machine unit (±10V), otherwise an Overflow happens and the overflow LED will shine 
. See Logic levels for details.
Extended Usage of an Integrator
Changing the integration speed
You can change the integration time scale factor k0 of a particular integrator by connecting SLOW to OUT. The circuit from the right actually stems from File:Anathing v1.0 base 3.pdf. By slowing down, you effectively decrease the k0 by factor 100.
Making use of the Summing junction
See also XIR.
Mathematics about analog integration
