Passive elements
================

The THAT comes with multiple passive elements, which require no supply voltage to fuction.
The following passive elements can be found on a THAT:

- Resistor network (XIR)
- Capacitors
- Diodes


Resistor network (XIR)
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   * - .. image:: ../../images/computing_elements/xir_that.png
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     - .. image:: ../../images/computing_elements/xir_circuit.png
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   * - THAT XIR unit
     - THAT XIR electrical circuit
     
The XIR elements can be used to increase the number of inputs of an integrator or a summer by simply connecting the SJ panel of an integrator/summer with the SJ panel of a XIR element. The free XIR inputs now function as inputs for the corresponding computing element.

They can also be used to convert an inverter to a summer, again by connecting the SJ panels.

Capacitors
----------

There are five free capacitors to be found on each THAT, three with 100 picofarad and two with 100 nanofarad. 

Diodes
------

There are six free diodes on each THat, four standard diodes and two Z-diodes.
Diodes can for example be used to generate stabilzed sinus functions.