Difference between revisions of "Coefficients/Potentiometers"

From TheAnalogThing
(syntax fix)
(Added an example)
 
(25 intermediate revisions by 2 users not shown)
Line 1: Line 1:
−
[[File:Coefficients Howto.png|thumb|400px|Howto use coefficients: Different blocks highlighted on [[The Analog Thing]] frontpanel]]
+
'''Coefficients''' are the quantitative parameters of analog computations. [[The Analog Thing]] features eight coefficient potentiometers, allowing the use of up to eight coefficients in an analog program on a single THAT.
 +
Using the potentiometers, each coefficient can be set to any value between <code>0</code> and <code>1</code>. An input to a coefficient potentiometer is multiplied by the value the coefficient potentiometer is set, such that their output is given by <code>output = coefficient * input</code>, with the coefficient being a value between 0 and 1 as said before.
  
−
'''Coefficients''' are constant values during a computation and used in a multiplicative fashion within the circuit. Coefficients can be tuned to any value between logical -1 and +1. Their output is just given by <code>output = coefficient * input</code>. In [[The Analog Thing]], there are eight coefficients available and the value for coefficients is tuned by rotating a '''potentiometer'''. That means you can perform the computation <code>output = coefficient * input</code> eight times in a circuit.
+
For example a variable A is patched into a potentiometer set to 0.123. The output of the potentiometer would be A*0.123, with the same sign as A. No sign reversal is possible with "normal" potentiometer, though tricks have been developed to allow such a thing.  
  
−
== How to use a coefficient ==
+
Several sections of the THAT user interface relate to the use of coefficient potentiometers, as shown in Figure 1:
−
Say you want to compute <code>+0.5 = 0.5 * (+1)</code>. Then follow these steps:
 
  
−
# First, decide which coefficient to use. They are numbered, say you want to use number 1.
+
* The <code>COEFFICIENTS</code> section. This is the area labelled <code>COEFF</code> on your THAT. It contains the input and output sockets for the coefficient potentiometers.
−
# Put a plug into the input for coefficient 1. Connect it to some +1 source.
+
* The <code>COEFFICIENT POTENTIOMETERS</code> section. It contains the eight rotary knobs by which coefficients can be set.
−
# Put a plug into the output of coefficient 1 and use it wherever you want.
+
* The <code>MODE SELECTOR</code>.
−
# Tune the potentiometer to the middle/center, around 0.5
+
* The <code>COEFFICIENT SELECTOR</code>. It is used to select the coefficient value to display on the <code>PANEL METER</code> when the <code>MODE SELECTOR</code> is in the <code>COEFF</code> position.
 +
* The <code>PANEL METER</code>.
  
−
== How to fine-tune a potentiometer ==
+
To familiarize yourself with the use of coefficient potentiometers, follow these steps:
  
−
There is a special [[mode]] for fine tuning these parameters, called <code>COEFF</code>. In this mode, the [[Voltmeter]] will display the exact value of the meter position of the potentiomer chosen in the coefficient plug (highlighted in red).
+
# Set the <code>MODE SELECTOR</code> to position <code>COEFF</code> and set the <code>COEFFICIENT SELECTOR</code> to position <code>1</code>. This connects the output of potentiometer <code>COEFF 1</code> to the <code>PANEL METER</code>.
 +
# Use a patch cable to connect one of the <code>+1</code> sockets in the <code> STABILIZED &#177;1</code> section to the input (circle) associated with potentiometer <code>COEFF 1</code> in the <code>COEFFICIENTS</code> section (i.e., the uppermost circled socket in the section labelled <code>COEFF</code> on your THAT).
 +
# Change the position of the <code>COEFF 1</code> knob in the <code>COEFFICIENT POTENTIOMETERS</code> section and observe the value displayed on the <code>PANEL METER</code>. The displayed value is available at the output (triangle) associated with potentiometer <code>COEFF 1</code> in the <code>COEFFICIENT</code> section.
 +
# Remove the patch cable plug from the <code>+1</code> socket in the <code> STABILIZED &#177;1</code> section and plug it into one of the <code>-1</code> sockets in in the <code> STABILIZED &#177;1</code>.
 +
# Again, change the position of the <code>COEFF 1</code> knob in the potentiometer section and observe the value displayed on the <code>PANEL METER</code>.
 +
# Set the <code>COEFFICIENT SELECTOR</code> to any one of the other potentiometers (say, 4).
 +
# Use a patch cable to connect either of the <code>-1</code> sockets in the <code> STABILIZED &#177;1</code> with the input (circle) associated with the with the coefficient potentiometer you have chosen using the <code>COEFFICIENT SELECTOR</code> (say, 4).
 +
# Change the position of the coefficient potentiometer knob associated with the coefficient you have chosen using the <code>COEFFICIENT SELECTOR</code> (say, 4) and again observe the value displayed on the <code>PANEL METER</code>.
 +
 
 +
[[File:THAT_legend_potentiometers_s.png|thumb|left|800px|Figure 1: Parts of the THAT user interface that relate to the familiarization steps described above]]
  
 
[[Category:Components of The Analog Thing]]
 
[[Category:Components of The Analog Thing]]

Latest revision as of 16:54, 30 December 2024

Coefficients are the quantitative parameters of analog computations. The Analog Thing features eight coefficient potentiometers, allowing the use of up to eight coefficients in an analog program on a single THAT. Using the potentiometers, each coefficient can be set to any value between 0 and 1. An input to a coefficient potentiometer is multiplied by the value the coefficient potentiometer is set, such that their output is given by output = coefficient * input, with the coefficient being a value between 0 and 1 as said before.

For example a variable A is patched into a potentiometer set to 0.123. The output of the potentiometer would be A*0.123, with the same sign as A. No sign reversal is possible with "normal" potentiometer, though tricks have been developed to allow such a thing.

Several sections of the THAT user interface relate to the use of coefficient potentiometers, as shown in Figure 1:

  • The COEFFICIENTS section. This is the area labelled COEFF on your THAT. It contains the input and output sockets for the coefficient potentiometers.
  • The COEFFICIENT POTENTIOMETERS section. It contains the eight rotary knobs by which coefficients can be set.
  • The MODE SELECTOR.
  • The COEFFICIENT SELECTOR. It is used to select the coefficient value to display on the PANEL METER when the MODE SELECTOR is in the COEFF position.
  • The PANEL METER.

To familiarize yourself with the use of coefficient potentiometers, follow these steps:

  1. Set the MODE SELECTOR to position COEFF and set the COEFFICIENT SELECTOR to position 1. This connects the output of potentiometer COEFF 1 to the PANEL METER.
  2. Use a patch cable to connect one of the +1 sockets in the STABILIZED ±1 section to the input (circle) associated with potentiometer COEFF 1 in the COEFFICIENTS section (i.e., the uppermost circled socket in the section labelled COEFF on your THAT).
  3. Change the position of the COEFF 1 knob in the COEFFICIENT POTENTIOMETERS section and observe the value displayed on the PANEL METER. The displayed value is available at the output (triangle) associated with potentiometer COEFF 1 in the COEFFICIENT section.
  4. Remove the patch cable plug from the +1 socket in the STABILIZED ±1 section and plug it into one of the -1 sockets in in the STABILIZED ±1.
  5. Again, change the position of the COEFF 1 knob in the potentiometer section and observe the value displayed on the PANEL METER.
  6. Set the COEFFICIENT SELECTOR to any one of the other potentiometers (say, 4).
  7. Use a patch cable to connect either of the -1 sockets in the STABILIZED ±1 with the input (circle) associated with the with the coefficient potentiometer you have chosen using the COEFFICIENT SELECTOR (say, 4).
  8. Change the position of the coefficient potentiometer knob associated with the coefficient you have chosen using the COEFFICIENT SELECTOR (say, 4) and again observe the value displayed on the PANEL METER.
Figure 1: Parts of the THAT user interface that relate to the familiarization steps described above
Retrieved from "https://the-analog-thing.org/w/index.php?title=Coefficients/Potentiometers&oldid=1021"