TheAnalogThing - User contributions [en]

Testing

2021-09-21T12:43:30Z

TimStinchcombe: typo

The following steps describe how to test your [[The Analog Thing|ANALOG THING]] thoroughly.

* Adjust the DVM and check the coefficient potentiometers:
** First of all, set the mode control switch on the bottom right to OFF.
** Connect THE ANALOG THING to a 5V USB power supply by means of a USB-A/USB-A cable.
** Set the mode control switch to COEFF. In this mode the coefficient potentiometers can be set with the DVM showing the current value of any of the eight coefficient potentiometers COEFF 1..COEFF 8.
** Set the COEFFICIENT switch to 1.
** Set the potentiometer COEFF 1 fully counter clockwise. The DVM should now display zero (a slight deviation from zero is permissible, so a displayed value of 0.003 would be OK, too).
** Now turn the potentiometer COEFF 1 fully clockwise.
** Adjust R14 (right side of THE ANALOG THING) with a tiny screw driver until the DVM displays 1.000.
** Check the remaining potentiometers by stepping the COEFFICIENT switch through positions 2 to 8 while setting each of the remaining potentiometers first fully counter clockwise and then fully clockwise. The DVM should display (nearly) zero and 1.000 in these two cases.

* Test the summers and inverters:
** Set the mode switch to IC (initial condition).
** The following steps are to be performed for each of the four summers:
*** Connect the jack labelled U on the front panel with one of the output jacks of the summer being tested. Connect one of the inputs with weight 1 with the machine unit -1 (lower left corner of the patch field). The DVM should display a value very near to +1.000.
*** Connect the -1 machine unit shortly with one of the summer inputs weighted with 10. The DVM must show a value in excess of 1.100 and the overload indicator OL should be lit.
** Perform the first of these steps with each of the four inverters. (Do not connect -1 or +1 directly to the summing junction input SJ.)

* Test the multipliers (perform the following steps for each of the two multipliers available on the analog computer):
** Connect the DVM to the output of the multiplier being tested.
** Connect the two inputs of the multiplier with +1 and +1 and check that the DVM reads very near to 1.000.
** Connect the two inputs of the multiplier with -1 and -1 and check that the DVM reads very near to +1.000.
** Connect one input to +1 and one input to -1. The DVM should now read very near to -1.000.

* Test the comparators (perform the following steps for each of the two comparators):
** Connect the >0 input with +1 and the <0 input with -1.
** Connect the DVM with the OUT jack of the comparator.
** Connect either A or B with +1 and then with -1. The DVM display must switch between near +1.000 and -1.000.

* Test the integrators (perform the following steps for each of the five integrators):
** Make sure the mode switch is set to initial condition (IC).
** Connect -1 to the IC input of the integrator.
** Connect the DVM (the jack labelled U) with the output of the integrator.
** Check that the DVM shows near +1.000. With IC connected to +1 instead, the DVM should read near -1.000. If this is the case, IC mode works.
** Connect the jack labelled SLOW with OUT of the integrator under test, thus selecting a low time scale factor.
** Connect the IC jack with +1, and connect one of the inputs with weight 1 with -1.
** The DVM should now read near -1.000.
** Set the mode selector switch to operate (OP). The DVM display should now increase quickly from about -1.000 to > 1.000 and the overload indicator OL will be lit.

A more thorough test of the integrators can (and should) be done with an external oscilloscope or a sound card "oscilloscope" as follows:
* This test requires two integrators and one inverter.
* Set the mode select switch to initial condition (IC).
* Connect the slow jack of each of the two integrators with an output jack of the very same integrator, thus selecting a low time scale factor.
* Connect IC of the 1st integrator (I1) to +1.
* Connect the output of I1 with an input with weight 1 of the 2nd integrator (I2).
* Connect the output of I2 with the input of an inverter.
* Connect the output of that inverter with an input with weight 1 of I1. (This circuit now solves the differential equation y'' = -y.)
* Connect the output of I1 with the jack labelled X.
* Connect the X output at the back of THE ANALOG THING with an oscilloscope or a sound card input (some oscilloscope software is assumed to be up and running on your computer).
* The oscilloscope should display a line at -1 (the output jacks are fed by a voltage divider so the actual reading is less than the machine unit voltage of -10V - this was done to avoid damage to an attached sound card).
* Set the mode selector switch to operate (OP). The oscilloscope will now display a rather low frequency sine curve.
* Set the mode selector switch back to IC and remove the two connections between SLOW and the OUT jack of each of the two integrators.
* Set the mode selector to OP. The oscilloscope should now display a sine wave with much higher frequency (factor 100) than before. (This signal's amplitude may increase or decrease over time which is normal and more or less unavoidable in a simple setup like this.)

The only thing left to test is the repetitive mode of operation:
* Turn the potentiometer labelled OP-TIME fully counter clockwise.
* Set the mode selector switch to REP.
* The LEDs OP and IC should be flickering.
* Slowly turning the OP-TIME potentiometer clockwise should cause the OP indicator light for longer and longer periods of time.
* Perform this test also with the mode selector switch in REPF (fast repetitive mode).

[[Category:Getting started]]

Summer

2021-09-19T18:14:19Z

TimStinchcombe: typo

[[File:Greek uc sigma.svg|thumb|120px|The greek symbol ''Sigma'' is the mathematical notation for a sum]]
A '''Summer''' is an elementary analog computing element. It carries out a '''summation''' of its inputs, as in <code>a + b = c</code>. Here, <code>a</code> and <code>b</code> are called the ''summands'' and <code>c</code> is the ''sum''. [[The Analog Thing]] features four summers, allowing four summations in a circuit.

== Elements of Each Summer on The Analog Thing ==

* Circles represent inputs, triangles represent outputs.
* Each of the summers of THAT has four unweighted inputs (labeled 1) and three inputs weighted with factor 10 (labeled 10).
* In the lower right corner of each of the summers, a <code>GROUND</code> socket (0) is available.
* Each of the summers has an <code>SJ</code> and en <code>FB</code> socket. Beginners may ignore these for the time being.
* Each of the summers has two output sockets.

== Basic Usage of a Summer on The Analog Thing ==
[[File:Summer.png|thumb|All connector sockets of a single summer]]
* Put each quantity you want to sum into a different circle. Do not stack connectors on the inputs.
* You can use both output sockets as you like and stack connectors however you like.

[[File:Nuvola apps important.svg|16px]] Attention: Make sure the sum of your inputs does not exceed the machine unit (±1), otherwise an overload occurs (indicated by the <code>OL LED</code>) [[File:Red rouge.svg|16px]]. See [[Machine Units]] for details.

== Extended Usage of a Summer ==

* If you choose input weight 10, you perform an amplification of this input. For details, see below.
* ...

== Mathematics and Electronics about analog summing ==
{{todo|Show definition equation, tell more}}

<code>
sum = - weight1 * input1 + weight2 * input2 + ...
</code>

Summation in analog computers is based on ''Kirchhoffs Law'', which describes the conservation of current, or electrons, in particular. In a summing point (''summing junction''), the sum of the incoming and outgoing currents add up to zero. Summers are implemented with ''closed-loop operational amplifiers'' [https://en.wikipedia.org/wiki/Operational_amplifier#Closed-loop_amplifier]. On [[THAT]], you find the corresponding electronic circuits in [[:File:Anathing_v1.0_base_3.pdf]]. As you can see there, summers (as well as [[Integrator]]s) are implemented with ICs called <code>TL074H</code>. If you look for the [https://www.ti.com/lit/ds/symlink/tl074h.pdf?ts=1628761245896&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTL074H Datasheet for the TL074H], you find for instance section ''6.17 Electrical Characteristics: TL07xH'' on page 17.



== Other summers in The Analog Thing ==

[[Inverter]]s are electronically identical to summers. With their summing junctions, they can be used as summers if no more summers are available. See the article about [[Inverter]]s and the [[XIR]] for more details. The [[Integrator]]s are by definition also summing but cannot be stopped from integrating except in IC mode (see [[Modes]]).

[[Category:Components of The Analog Thing]]

Summer

2021-09-19T18:12:55Z

TimStinchcombe: typos

[[File:Greek uc sigma.svg|thumb|120px|The greek symbol ''Sigma'' is the mathematical notation for a sum]]
A '''Summer''' is an elementary analog computing element. It carries out a '''summation''' of its inputs, as in <code>a + b = c</code>. Here, <code>a</code> and <code>b</code> are called the ''summands'' and <code>c</code> is the ''sum''. [[The Analog Thing]] features four summers, allowing four summations in a circuit.

== Elements of Each Summer on The Analog Thing ==

* Circles represent inputs, triangles represent outputs.
* Each of the summers of THAT has four unweighted inputs (labeled 1) and three inputs weighted with factor 10 (labeled 10).
* In the lower right corner of each of the summers, a <code>GROUND</code> socket (0) is available.
* Each of the summers has an <code>SJ</code> and en <code>FB</code> socket. Beginners may ignore these for the time being.
* Each of the summers has two output sockets.

== Basic Usage of a Summer on The Analog Thing ==
[[File:Summer.png|thumb|All connector sockets of a single summer]]
* Put each quantity you want to sum into a different circle. Do not stack connectors on the inputs.
* You can use both output sockets as you like and stack connectors however you like.

[[File:Nuvola apps important.svg|16px]] Attention: Make sure the sum of your inputs does not exceed the machine unit (±1), otherwise an overload occurs (indicated by the <code>OL LED</code>) [[File:Red rouge.svg|16px]]. See [[Machine Units]] for details.

== Extended Usage of a Summer ==

* If you choose input weight 10, you perform an amplification of this input. For details, see below.
* ...

== Mathematics and Electronics about analog summing ==
{{todo|Show definition equation, tell more}}

<code>
sum = - weight1 * input1 + weight2 * input2 + ...
</code>

Summation in analog computers is based on ''Kirchhoffs Law'', which describes the conservation of current, or electrons, in particular. In a summing point (''summing junction''), the sum of the incoming and outgoing currents add up to zero. Summers are implemented with ''closed-loop operational amplifiers'' [https://en.wikipedia.org/wiki/Operational_amplifier#Closed-loop_amplifier]. On [[THAT]], you find the corresponding electronical circuits in [[:File:Anathing_v1.0_base_3.pdf]]. As you can see there, summers (as well as [[Integrator]]s) are implemented with ICs called <code>TL074H</code>. If you look for the [https://www.ti.com/lit/ds/symlink/tl074h.pdf?ts=1628761245896&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTL074H Datasheet for the TL074H], you find for instance section ''6.17 Electrical Characteristics: TL07xH'' on page 17.



== Other summers in The Analog Thing ==

[[Inverter]]s are electronically identical to summers. With their summing junctions, they can be used as summers if no more summers are available. See the article about [[Inverter]]s and the [[XIR]] for more details. The [[Integrator]]s are by definition also summing but cannot be stopped from integrating except in IC mode (see [[Modes]]).

[[Category:Components of The Analog Thing]]

Multiplier

2021-09-19T17:58:41Z

TimStinchcombe: minor spelling

The '''Multiplier''' is an analog computing element which is capable of performing the multiplication of two quantities <code>X * Y = OUT</code>. We call <code>X</code> and <code>Y</code> the ''factors'' and <code>OUT</code> the ''product''. [[The Analog Thing]] has two multipliers, which means you can do two multiplications in a single circuit. However, alternatives exist: If you only want to multiply by a constant, use a [[Coefficient/Potentiometer]].

Multiplication in electrical analog computers is one of the hardest basic arithmetic operations, since there is no fundamental process in nature which could be exploited. The THAT features a four quadrant multiplier (Gilbert cell) which is by far the most expensive part of the overall board. This is the reason why there are only two multipliers on the overall board.

== Usage of the Multiplier ==
[[File:Multipliers.png|thumb|The picture shows ''two distinct'' multipliers, one per row]]

* Choose one multiplier which is free. Each row is a single multiplier.
* Connect something to the inputs (round circles <code>X</code> and <code>Y</code>). Only connect a single jack, do not stack jacks.
* Use the output (triangular circuit), you can connect multiple jacks if you want.

Interestingly, the multiplication can never produce an overload. This is easy to see: If <code>-1 < X < 1</code> and <code>-1 < Y < 1</code>, then <code>0 < Z < 1</code>.

== Chip ==
In [[The Analog Thing]], the ''AD633JR'' is used for multiplication. You can find it in the schematics for instance in [[:File:Anathing_v1.0_base_4.pdf]].

[[Category:Components of The Analog Thing]]

Oscilloscope

2021-09-19T17:51:14Z

TimStinchcombe: minor spelling & readability

An '''Oscilloscope''' is an essential measurement device when doing analog computing. Nevertheless, even cheap entry level devices cost more than 200 EUR. This page shall document how to use oscilloscopes with [[THAT]] and gives recommendations about devices that are suitable for working with [[The Analog Thing]]. If you don't want to spend money on an oscilloscope, a [[Software Oscilloscope]] maybe an alternative.

== Using Oscilloscopes ==
To watch and measure the values and curves produced during an analog computation or simulation you need additional instruments. The Analog Thing contains a [[voltmeter]] as instrument to setup the coordinates or OP_TIME values. Depending on the [[modes|mode of operation]] in '''REP''' with predefined operation time or '''OP''' with infinite operation this display may be useful for static or slow moving values only.

[[Image:DSO_Yt_display.png|thumb|typical Yt display of signals on a DSO]]
To measure faster events or display signal curves the best tool is an '''oscilloscope'''. For longer operation times (REP, 0.1-10s) a digital storage oscilloscope (DSO) is preferred rather than an analog oscilloscope with a cathode ray tube (CRT). These DSO did get cheaper in the last years but useful DSO's with minimum 2 channels and XY mode are in the price range of about 150-300 € up. XY mode is useful for many applications and allow a better view of complex signals than displaying them just over the time in Yt mode. The typical Lissajous figures for example require the XY mode.

[[Image:DSO_XY_display.png|thumb|typical XY display of the same signals above]]
There are low cost oscilloscope on the market as well in the range of 40-100 € but these come with missing features and have mostly only one channel to display like DSO 138 or missing XY mode like DS 212/213. This is only partly useful with analog computations or simulations and all theses cheap handhelds have only a very small display. Some low cost oscilloscopes come without a display and are connected to a computer as display by software.

== Requirements for Oscilloscopes with The Analog Thing ==
=== Minimum requirements (cheap devices) ===
* analog oscilloscope with CRT display or software display while connected to computer
* 1 or 2 channels
* XY display mode
* 100 kHz bandwith

Recommendations:
* [https://www.meilhaus.de/picoscope-2000.htm Picoscope] (125€ entry price)
* [https://store.digilentinc.com/analog-discovery-2-100msps-usb-oscilloscope-logic-analyzer-and-variable-power-supply/ Analog Discovery 2] (280€ for academic)
* [https://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/adalm2000.html#eb-overview ADMAL2000]

Further cheap alternatives:
* HS101 http://hscope.martinloren.com/HS101-oscilloscope.html
* DroidOscillo https://hackaday.io/project/26360-android-oscilloscope-droidoscillo
* DSO-138 https://www.reichelt.de/dso-138-oszilloskop-1-kanal-200-khz-12-bit-joy-it-dso-138-p209775.html?&trstct=pol_0&nbc=1
* SmartScope https://www.kickstarter.com/projects/751733865/smartscope-reinventing-the-oscilloscope

=== Medium requirements ===
* 4 channels or separate trigger input
* DSO type (digital storage)

== Alternatives ==
There is a cheaper alternative for beginners with low budget while using a [[Soundcard Oscilloscope]] software. These solutions are based on using a sound input of the computer and a software to display the signal while reading digitized data of AD converters on the soundcard. If your computer contains a sound input you are lucky as you can get the software for free. Unfortunately many newer computers no more have classical sound input in stereo (so called 'line-in') and if so it is mostly only a microphone input as mono (1 channel instead of 2). This is the same lack as an oscilloscope with only 1 input channel.

[[Category:Hardware]]