{"id":407,"date":"2016-06-04T08:59:14","date_gmt":"2016-06-04T15:59:14","guid":{"rendered":"http:\/\/www.f15sim.com\/?p=407"},"modified":"2016-06-04T08:59:14","modified_gmt":"2016-06-04T15:59:14","slug":"new-gauge-design","status":"publish","type":"post","link":"https:\/\/www.f15sim.com\/?p=407","title":{"rendered":"New gauge design!"},"content":{"rendered":"

I spent quite a while working on getting the air core motors to work properly.\u00a0 The biggest issue was the sound they made due to the PWM signal resonating in the instrument shell.\u00a0 I did get the sound to go away, but at the required frequency the motor would no longer move properly.\u00a0 This lead me to look into other methods I could use that would still fit into a 2″ MS33639 instrument shell.<\/p>\n

Many years ago I briefly looked into the micro stepper motors made by Switec.\u00a0 They were fairly new on the scene and were nice, but expensive motors.\u00a0 Fast forward about 12 years and I find that you can obtain these motors for as little as $2.50 each! (lot of 25 on eBay)\u00a0 My search for more information on the motor led me to an Arduino project where the goal was to use these steppers in various projects.\u00a0 The cool thing is that due to the low power consumption of the coils, they could be directly driven from an Arduino without the need for an h-bridge chip! (20mA per coil) The blog entry that I found is here: http:\/\/guy.carpenter.id.au\/gaugette\/2012\/01\/05\/what-is-gaugette\/ – I’d recommend you read the rest of his blog – there’s a ton of great information on using Switec motors, including with a Raspberry Pi.<\/p>\n

I did a bit more research and found a demonstrator project on Tindie that used a Switec motor – https:\/\/www.tindie.com\/products\/TheRengineer\/analog-gauge-stepper-breakout-board.\u00a0 The board allowed for easy connection to an Arduino and included clamping diodes to prevent back-EMF from doing damage to the Arduino.\u00a0 Since the board was way too large for my needs, I re-designed it to use surface mount diodes (LL4148) and reduced the size of the board to match the diameter of a Switec motor.<\/p>\n

\"switec-and-pcb\"<\/a><\/p>\n

The 4 pin connector along the bottom is for the two coils in the motor and the 2 pin connector at the top is for the 5v reference voltage for the diodes.<\/p>\n

I revised my gauge code to use the Switec X25 library and it works great!\u00a0 The motor I’m using is the X27.168 and has an internal stop.\u00a0 The 2″ gauges in the F-15 don’t require more than 300 degrees of rotation at the most, so this is a perfect choice – it allows me to rotate backwards to hit the stop and then start from a known point.\u00a0 The idea being to use the stop in lieu of a “home” position detector.<\/p>\n

Unfortunately, changing to the Switec motor required that I completely re-design the “middle” section of the gauge.<\/p>\n

Here’s the result of that redesign:<\/p>\n

\"v2-gauge-iso-1-sm\"<\/a> \"v2-gauge-iso-2-sm\"<\/a><\/p>\n

The resulting assembly is going to be roughly 3\/4″ shorter than the original, air-core based design.\u00a0 I’m currently printing the new components as I write this.\u00a0 The photo below is the new center mating clip.<\/p>\n

\"center<\/a><\/p>\n

This part attaches to the back half of the instrument using two screws.\u00a0 It is connected to the motor and instrument face using a pair of 0-80 screws that pass through the stepper motor and end up in heat-set inserts installed in the standoffs on the instrument face.<\/p>\n

 <\/p>\n

 <\/p>\n

I also got the chance to get the finishing touches done on the gauge face graphics.\u00a0 I had them printed up on 120lb card stock at Staples:<\/p>\n

\"gauge<\/a>The plan is to cut them out on the laser and then glue them to the gauge faces after assembly.\u00a0 I had enough made to ensure that I’ll have spares when I inevitably screw one up. \ud83d\ude42 I really like how they turned out!<\/p>\n

Thanks for reading!<\/p>\n","protected":false},"excerpt":{"rendered":"

I spent quite a while working on getting the air core motors to work properly.\u00a0 The biggest issue was the sound they made due to the PWM signal resonating in the instrument shell.\u00a0 I did get the sound to go away, but at the required frequency the motor would no longer move properly.\u00a0 This lead […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-407","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/www.f15sim.com\/index.php?rest_route=\/wp\/v2\/posts\/407","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.f15sim.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.f15sim.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.f15sim.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.f15sim.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=407"}],"version-history":[{"count":1,"href":"https:\/\/www.f15sim.com\/index.php?rest_route=\/wp\/v2\/posts\/407\/revisions"}],"predecessor-version":[{"id":413,"href":"https:\/\/www.f15sim.com\/index.php?rest_route=\/wp\/v2\/posts\/407\/revisions\/413"}],"wp:attachment":[{"href":"https:\/\/www.f15sim.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=407"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.f15sim.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=407"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.f15sim.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=407"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}