{"id":2109,"date":"2019-08-14T14:57:22","date_gmt":"2019-08-14T14:57:22","guid":{"rendered":"http:\/\/volksswitch.org\/?page_id=2109"},"modified":"2020-07-05T22:40:14","modified_gmt":"2020-07-05T22:40:14","slug":"version-4-eliminating-the-need-for-breadboards","status":"publish","type":"page","link":"https:\/\/volksswitch.org\/index.php\/volks-devices\/the-volksswitch\/version-4-eliminating-the-need-for-breadboards\/","title":{"rendered":"Version 4: Eliminating the need for breadboards and soldering"},"content":{"rendered":"\n

Breadboards can be expensive and they’re naturally bulky.\u00a0 Because they’re bulky, they may unnecessarily force a minimum height for the switch. Maybe worse, they present a grid of holes that have to be filled correctly with components and wires if the circuit is expected to function properly.<\/p>\n

The goal of this version is to provide an alternative solution to breadboards but not to require the person assembling the switch to have all the specialized equipment and skill necessary to safely solder components together.\u00a0 At the same time, we looked at how we could eliminate the requirement to select the proper gauge of wire and properly strip away the insulation.<\/p>\n

In a few words, the goal is to design into the 3D object as much of the circuit design as possible and to use a liquid solder equivalent (a conductive paste) that can be injected into the 3D printed parts to join the electronic components.<\/p>\n

This design requires two specific electronic components, a specific micro-switch and a specific headphone jack.\u00a0 The design was modeled in Fusion 360 to match these specific components.\u00a0 However, it’s easily conceivable that the design could be programmed, using OpenSCAD, to support an arbitrary set of micro-switches and headphone jacks.<\/p>\n

Here are the specific headphone jack and micro-switch (along with links to purchase them on Amazon.com):<\/p>\n\n\n\n\n
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headphone jack<\/a><\/td>\nmicro-switch<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

If the leading pin of the headphone jack is bent as it appears to be in the picture above, gently bend it straight up before inserting it into the mount so it aligns properly with the provided hole.<\/p>\n

Here are the mounts for the headphone jack and the micro-switch.\u00a0<\/p>\n

The headphone jack mount has a base and a cover.\u00a0 The purpose of the cover will become clear later.\u00a0 The holes and slots on the surface of the mount are there to accommodate the pins and bumps on the underside of the jack.\u00a0 Two of the holes have a funnel shaped opening because they will be the point where the conductive paste is injected.<\/p>\n

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The micro-switch mount is simpler.\u00a0 Again there are two holes with a funnel shaped opening for injecting the conductive paste.<\/p>\n

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Both mounts should be printed at a small layer height to ensure that the channels are accurately printed.\u00a0 The mounts that were tested for this design were printed with a 0.15 mm layer height.<\/p>\n

The horizontal arms on either side accommodate two\u00a0 breadboard jumper wires<\/a>:<\/p>\n

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The wires come with both ends “pre-stripped” and with a plastic collar to aid insertion into the component mounts.<\/p>\n

The two mounts have “internal plumbing” that joins the proper pins of the headphone jack and micro-switch to the ends of the jumper wires.\u00a0 These pictures show each component along side its internal plumbing:<\/p>\n\n\n\n\n
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\"\"<\/a><\/td>\n\"\"<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Each injection port has a corresponding overflow port.\u00a0 The overflow port provides a visual way to identify when the internal chamber has been sufficiently filled with paste:<\/p>\n

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The conductive paste (called conductive paint, by the manufacturer) comes from from Chip Quik:<\/a><\/p>\n

\"\"<\/a>The smallest syringe holds 5 grams of paste and only about 0.2 grams are needed to assemble a switch.\u00a0 You can purchase a nylon sleeve<\/a> to fit over the end of the metal needle which will keep the paste from drying in the syringe.\u00a0 The paste has a shelf life of over a year.\u00a0 That’s enough time to print and assemble lots of switches.<\/p>\n

The switch base has indents to aid in placing the mounts and, in the case of the headphone mount, is designed to allow the mount to slide into the wall of the base after the mount is assembled with the jack inside.<\/p>\n

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The flexure spring has been retained from the previous version with a small change.\u00a0 The block which held the headphone jack in place in the previous version has been removed because it is no longer needed.\u00a0 A cut is added to each edge to provide clearance for the clips built into the cover.<\/p>\n

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The cover has been modified with clips that fit into slots on each side of the base.\u00a0 These clips, along with the friction of the two surfaces, is sufficient to hold the cover to the base without the use of screws.<\/p>\n

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The post, activation surface, and activation surface mount have been preserved, unchanged from the previous version.\u00a0 Two post lengths are provided as STL files.\u00a0 One is 3 mm long and the other is 6 mm long.\u00a0 The shorter the length, the longer the activation distance.\u00a0 All the parts, together, look like this:<\/p>\n

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The STL files for this design can be found on Thingiverse at: https:\/\/www.thingiverse.com\/thing:3819575<\/a><\/p>\n

The following video shows how to assemble the switch:<\/p>\n