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| Batteries can be especially problematic in this case if there's no way to stop the current and thus heat. If you're using batteries make sure there's safety measures in place to stop the current, such as a fuse. | | Batteries can be especially problematic in this case if there's no way to stop the current and thus heat. If you're using batteries make sure there's safety measures in place to stop the current, such as a fuse. |
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| | === Electro-static discharge === |
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| | * Components may hold charge |
| | * Electro-static discharge may damage the components |
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| === Powered components === | | === Powered components === |
| Touching a component can potentially add you to a circuit. Depending on what type of circuit this is this may do nothing, it may damage the component, or it may damage you. There are two particular categories of circuits you should watch out for: Low voltage and high voltage.
| | - high voltage |
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| | - shocks |
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| The human body does not conduct much electricity at low voltage (I'll use 12 volts as my conservative definition here) so it's unlikely you'll damage yourself by touching a component. It is possible to damage components by unintentional paths between components. There main technique to avoid this is to touch only the ground parts of the circuit such as metal USB or Ethernet shields.
| | === Charged components === |
| | - capctiros |
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| High voltage is a different story (I'll define it as over 50 volts here) as your body may conduct enough electricity to shock you. Do not touch high voltage components. If you're unsure, don't touch the component at all. It will not be an enjoyable experience and it will accomplish nothing.
| | - batteries |
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| === Charged components ===
| | - short circuits, shocks |
| Components like batteries or capacitors can hold charge despite a device being turned off. Everything in the 'powered components' section above applies to these components as they are effectively still on. Removing batteries is likely possible, but capacitors are trickier.
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| | high voltage |
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| | So far the following |
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| | This is a big TODO for me to dump my current knowledge. |
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| | See the main page for my contact details if you're interested or just leave a comment in the discussion page for this page. |
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| Capacitors can't hold charge long term like batteries. Most capacitors will discharge after a few seconds if not sooner. Touching the ends of low voltage capacitors with a finger can use your body to safely discharge the capacitor. The danger comes from large high voltage capacitors. Do not touch high voltage capacitors.
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| === Electro-static discharge ===
| | Idea dump: |
| The human body has the ability to act as a high voltage capacitor an deliver large shocks to electronic components. These shocks aren't large amounts of energy but still have the ability to damage components. Discharging these shocks may result in a light shock or no shock at all.
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| The solution here is to use an anti-static wrist strap and anti-static mat, with both of these connected to a common ground that connects to an earthed point in your house, or earthed appliance like a desktop computer case. This ensures that the components, you and your environment all share a common voltage level and dissipate capacitance.
| | - tactile electroncis |
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| == Learning and literacy ==
| | - deafblind |
| Like mathematics or any abstract medium, electronics is not easily observed by any human sense. It requires an abstract notation to describe and make predictions.
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| Unfortunately the current notation is heavily visual:
| | - electronics and components as an abstract should be accessible to blind people |
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| * Schematics display components and their connections using graphical drawings
| | - data sheets, schematics, pcbs, simulators, graphs, etc |
| * Signals and behaviour and depicted using two-dimensional graphs
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| * Mathematical notation and formulas are used for complex calculations
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| As far as I know there is no other formal notation for describing electronics than what I've listed above.
| | - though hole assembly should be doable one day |
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| The current approach I see is to have a sighted guide handle intake and description of data in to some informal notation.
| | - breadboards are doable |
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| == Tools ==
| | - esd mat |
| There are various tools used to investigate and study electronics:
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| * Multimeters to measure voltage, resistance and current of a circuit
| | - touch is discouraged |
| * Oscilloscopes to measure voltage waveforms of a circuit
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| * Component testers to determine what a component is and its value
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| * Electronic design automation software for creating schematics and PCBs
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| * Simulators to tests hypothetical circuits
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| Unfortunately these tools are not accessible to blind folk for a variety of reasons:
| | - do NOT touch high voltage |
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| * Physical devices lack braille or audio capabilities
| | - electronics is heavily visual based |
| * Software lacks screen reader support
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| * The notation used by software is visual
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| These aren't entirely unsolvable problems:
| | - containers to organize things |
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| * Some physical devices can be interfaced with a computer and read over USB or a serial port. The open source [https://sigrok.org/ sigrok] project is able to interface with various physical tools and read their displays.
| | - dangers of touching things |
| * Software that lacks screen reader support can in theory be fixed, or alternatives can be developed that use textual descriptions.
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| * Notion doesn't exactly matter when dealing with concrete things such as voltage at a location or specific components and simulators are used to experiment.
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| The current approach I have is to build a basic breadboard multimeter and component tester as well as document how to use things like logic analysers or oscilloscopes with sigrok.
| | - soldering and how we can't do that yet |
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| == Soldering ==
| | - desoldering and desoldering gun |
| Soldering is used to create strong electrical connects between components. The idea is simple:
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| * Put two electrically conductive surfaces together and heat them
| | - breadboards and breadboard wires |
| * Melt a solder alloy over the intersection to create a joint
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| * The joint holds the two surfaces together and conducts electricity
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| Soldering has a long history of being done by the blind. The [https://www.ski.org/smith-kettlewell-technical-file Smith Kettlewell Technical File] and [https://www.ski.org/soldering-basics Smith Kettlewell Soldering Basics] websites document techniques used to solder without vision.
| | - visual people as guides |
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| However these were written in the 1980s and 1990s. These days there's often an added requirement: Components must be placed through small holes on a circuit board, rather than free form. These holes are often placed extremely close together and lack thermal mass. This naturally requires a lot more precision.
| | - cameras, microscopes, etc |
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| Even sighted people have difficulty making these solder joints. It's common for magnifying glasses and microscopes to be used just to verify that joints are correct and functional.
| | - leads and future work |
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| The current approach I've been using is to avoid soldering and focus on solderless techniques such as breadboards. However many components require soldering additional pin headers to be usable with a breadboard, severely limiting the feasibility of this approach.
| | - mouser |
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| I fully believe that with the help of some jigs it would be possible to gain the level of precision required to do these joints.
| | - LEDs |
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| I'm unsure about the solution for soldering smaller surface mount components given there's no tactile indication available that the component is position properly. There are pick and place machines that can solder these components automatically but are very very expensive.
| | - buzzers |
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| == Breadboarding ==
| | - screwdrivers |
| Breadboards are currently the main way to do solderless electronics. It varies by breadboard but generally they contain:
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| * A grid of female holes spaced by 2.54mm
| | - parallel/series |
| * A series of short metal 'lanes' next to each under the holes, usually with half a dozen holes per lane
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| * These lanes grab on to things inserted in to the holes and electrically join them
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| * A gap down the middle separating two sets of lanes for inserting components pins on both sides
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| * Two very long lanes on each side that run in a different direction to regular lanes, usually used for power
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| * These long lanes may be split in to four on some breadboards
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| There are no tactile hints for which way the lanes run electrically. You can infer the direction as outside the long side lanes for power, lanes are always short not long. If you really want to check you can remove the adhesive backing and feel the metal contacts underneath.
| | - multimeters, oscilliscopes, component testers |
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| Here's a list of things you might want to make a breadboard electronics project:
| | - resistence soldering |
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| * Resistors
| | https://www.ski.org/soldering-basics |
| * Capacitors
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| * Diodes
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| * Transistors
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| * Buttons
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| * Buzzers
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| * Arduino Micros
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| * Multiple breadboards
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| * Lots of containers to hold things
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| You can find a lot of these on sites like [https://www.adafruit.com/ Adafruit], [https://www.sparkfun.com/ SparkFun], and [https://mouser.com/ Mouser].
| | https://www.ski.org/smith-kettlewell-technical-file |
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| If you're just confused about what to buy, contact me and I can give you some suggestions.
| | https://blarbl.blogspot.com/ |
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| Be sure to check out the [https://barbl.blogspot.com Blind Arduino Blog] and [https://groups.io/g/babamm/ Blind Arduino mailing list].
| | https://groups.io/g/babamm/ |
| [[Category:Research]] | | [[Category:Research]] |