Category — Cool Components
In the past at work we haven’t used rack mount keyboard drawers because all the models we could find were over $200.Â Instead, we designed our own that mounts on top of a rack mount PC.Â This design works fine, but it requires modifying the computer case.
Since we’re making some changes, I took another look, and finally found an affordable 19″ 1U (1.75″) keyboard drawer: the Penn Elcom EX6301B, which is available from Newark/Element14 here for about $80.
Actually, it’s not keyboard drawer: Penn Elcom calls it a laptop drawer.Â But it will work fine as a keyboard drawer as long as you are using a compact, slim keyboard such as the Adesso AKB-410UB.Â A standard keyboard is way too wide; my beloved Cooler Master Quickfire tk is narrow enough, but it’s too tall.
I’d also highly recommend using a keyboard with integrated track pad or trackball (the AKB-410UB has a track pad).Â With a narrow enough keyboard, you might be able to tuck a low profile mouse into the space, but you’d probably want a mouse pad, too, so you’re not running the mouse over the drawer’s mesh surface.
Penn Elcom doesn’t provide a lot of information (just some very basic dimensions), so we ordered a drawer to see if it would work — and decided it would.Â The build quality appears good, too.
May 30, 2015 No Comments
I have to say someday I’d like to make my own metal buttons.
In the past, I’ve covered Microchip’s mTouch metal-over-cap technology (here and here), which uses capacitive technology.Â Microchip has a groovy app note which shows some of the ways you can use it, and has an eval kit available for ~$150 (base mTouch kit plus metal over cap accessory kit).
Now TI has a reference design for creating your own metal buttons using TI’s inductive sensor technology.Â TI’s reference designs provide that: a reference design with layout, calculations, and notes.Â You can’t buy them pre-made, but you can use them as a good starting point.
I’ve glanced through the manual for this reference design, and it is full of good info – and the design is pretty neat, too.Â For example, it includes two different haptic types, ERM/LRM and piezo.Â I have the HapTouch Booster Pack which features the same ERM/LRM haptics technology, and I’m not too impressed – it’s similar to the haptic feedback from a current smartphone.Â (Note that I think the problem is with the basic ERM/LRM technology, not the controller).
Other approaches to non-moving metal buttons include piezo electric and ultrasonic.
March 19, 2015 No Comments
Most motors I’ve seen spin at the leisurely rate of 6000 RPM or less (heck, many are limited to 3000 RPM).
My Emoteq BH02300’s can do 20,000 RPM.
I’ve drooled over the specs for motors from Emoteq, Pittman, and Maxon that can do 60,000->100,000 RPM.Â (Yes, I’d love to own one).
But a Swiss company, Celeroton, takes the cake: they have motors and controllers that can do 500,000 RPM!Â Those must be totally groovy.
Celeroton sells brushless motors, drives, and compressors that useÂ their motors and electronics.Â The drives have a minimum speed of 5000 RPM; some models can handle up to 1,000,000 RPM maximum speed.Â The drives (or inverters, as Celeroton calls them) are available in 400W to 3Kw models, and are sensorless (no hall effect, encoder, or other sensors required).
A friend is looking into using the Celeroton drives with a merely fast motor (~100,000 RPM).Â If I get any real world feedback from him, I’ll update this post.
November 4, 2014 No Comments
In the past, I’ve always used fixed focus lenses for machine vision because although autofocus lenses are cool, they added a lot of cost and size and I could manage without them.
Last year at Photonics West, Varioptic had an impressive demo: two tiny 2D barcode readers (from Cognex and Microscan) that both sported autofocus lenses using Varioptic’s liquid lens technology.Â Back then, Varioptic only made autofocus modules in M12 size or smaller.Â Most machine vision cameras, however, use C or CS mount.Â (In the future, maybe Micro 4/3 (M43) will become common for machine vision, which would add a lot of affordable autofocus lenses, although they might not be optimized for machine vision).
Recently, however, Varioptic introduced a compact C-mount autofocus lens.Â It’s not a cure-all; I don’t know the price and currently only one model is available (16mm).Â Control options are analog, I2C, SPI, or RS-232.Â Next time I have to use machine vision, I might not use this lens, but I’ll definitely check out the details.
Here’s one example of why an autofocus lens can be handy: suppose I need to inspect different parts of various sizes.Â The camera is in a fixed location.Â The parts are picked up byÂ a robot, so I can move the parts to any desired distance from the camera.Â Ideally, I’d like to be able to position the part so that it fills most of the camera’s field of view, thus providing the best image.
However, if my depth of field is less than the distance between the optimal positions for the biggest and smallest parts, I will get less than optimal images, since I will have to position the smaller parts farther away (in my diagram above, at position 2 instead of 1).Â With an autofocus camera, I can either use an autofocus routine, or have a set focus position for each part size.Â Also, at times maximum depth of field is not desirable: sometimes a shallow depth of field gives an better inspection image, or you need to use less light (larger depth of field requires smaller aperture, which means more light is required for the same image brightness).
Blog note: I’m still working on the robot series, but the next few posts are taking more research and time than I expected.
December 5, 2013 No Comments
Sick sensors has a really cool web page showing their products sorted by supported fieldbus.Â It’s simple:
- Find the fieldbus you’re interested in; choices include CANOpen, DeviceNet, EtherCAT, EtherNet/IP, HIPERFACE, IO-Link, Modbus TCP, Profibus DP, Profinet, PROFIsafe, and SSI.
- Find the component type you’re interested in.Â What’s available varies with the fieldbus; for example, only measurement and feedback sensors are available for the SSI and HIPERFACE encoder buses.
- However, the major fieldbuses have a lot of available types, typically including absolute encoders, bar code scanners, 2D code readers (for Datamatrix and such), laser measurement, linear measurement, light curtains, network gateways, RFID, safety controllers, safety laser scanners, and hand-held scanners.
- Sometimes, adding fieldbus functionality requires a gateway module, or an external communications module.Â From a glance, it appears most safety communications (e.g. to safety controller) and most EtherCAT communications require a gateway — and those gateways can be pricey.
- Still, Sick’s level of fieldbus support is impressive.
- Then a new tab appears with search results for the component type, already filtered by fieldbus type.
September 3, 2013 No Comments
One complaint I have about most proprietary motion control field buses is that the I/O choices available are very limited.Â Standard field buses such as CANOpen, Ethernet PowerLink, and EtherCAT have a much better selection of I/O modules as well as a wide selection of drives, but there’s one device that’s hard to find on most motion networks, proprietary as well as standard: an interface to analog servo drives.
Analog servo amps are still important because specialized equipment such as piezo motors can require you to use a custom servo amplifier, which typically has a +/- 10V analog input.Â So if you want to use these devices on a network, you’re out of luck — unless you can get a network to analog drive.
The Logosol LDCN is the only proprietary motion network I know of that has drives with an analog output (they are the LS-160, LS-170F, and LS-180).
I’ve only found one company making analog output drives for a standard motion network: the ACS Motion EtherCAT intefaces.Â ACS has various models.Â The SPiiPlusUDI modules can control 2 or 4 analog servo amps.Â The SPiiPlusPDM modules can control 2 or 4 step/dir input drives, including step/dir servo drives, stepper drives, or laser generators.
I think the UDI modules are more useful, but I’m sure the PDM modules can be handy.Â For example, if you want to use a proprietary Asian servo motor that has to be used with a proprietary drive that takes step/dir input.
Important note: after I wrote this, I had a discussion with a local ACS distributor, and he said he was pretty sure that the ACS EtherCAT drives and modulesÂ will only work with ACS motion controllers (hardware or software).Â So, if you’re interested in these modulesÂ but don’t want to go 100% ACS, please check first.
May 30, 2013 No Comments
At the Design West 2012 / Embedded Systems Conference I had the opportunity to try out a unique technology: Microchip Technology’s mTouch metal over cap buttons.Â This technology provides the capability to fairly easily create affordable custom non-contact metal buttons.
Since this technology uses capacitive sensing, the buttons are non-contact and should have a long life.Â However, they’re still very short stroke and thus provide very little mechanical feedback.Â Microchip’s demo used LED point lights to provide feedback.Â Microchip’s demo kit currently isn’t available for sale, but they said it was coming sometime, probably for less than $100.
You could use this technology to make ESD-safe buttons.Â However, since the metal needs to bend a bit, it won’t be as rugged as the more expensive anti-vandal buttons.
I’ll probably buy the demo kit when it comes out, because it’s a cool gadget…
May 1, 2012 No Comments
Maybe, just maybe, I’m finished writing about buttons for a while.Â Â But first I want to mention a last few groovy pushbuttons.
Hall Effect Pushbuttons
Hall effect pushbuttons are cool because they have a stroke, like a mechanical pushbutton, but can last for millions of cycles.
- ITW Switches has a wide variety of hall effect pushbuttons, including metal and illuminated large panel mount switches, such as the Series 48SS, the 48M-SS, 57M-SS, and 58M-SS.Â However, availability is poor; for example at Mouser I only found a few 48SS models (but they were all less than $20).
- C&K has the HP series.
- APEM has the IH Hall Effect Switches.Â The IHS models are panel mount switches start at ~$40.Â The IHL models are unique: they have a linear 0.5->4.5V analog output over the switch’s 4mm travel, and cost ~$60.Â However, I think a T-Bar or one axis joystick would be a lot easier to use, although they would typically be larger and more expensive.
Finally, I have to mention Schurter’s MSM CS series: they are mechanical vandal-resistant switches with a ceramic actuator.Â The ceramic material makes for a very cool looking button; see the PDF datasheet for pictures.Â Prices start ~$25.
November 14, 2011 No Comments
While looking into ESD-safe buttons, I discovered quite a few metal buttons with no moving parts.Â These buttons do have some potential advantages including:
- Easier to use in ESD-safe applications (since there is only one part to ground, and many models are made of conductive metal).
- Great durability, up to 50 million cycles or more, since there is no mechanical wear.
- Better washdown and cleaning for medical and similar applications, because they have fewer cracks to hide nasty stuff.
- Better resistance against vandals (since the exposed part is made from one piece of metal).
Potential disadvantages include:
- No tactile feedback; great feedback is one of the best features of a good pushbutton.
- Very limited current switching ability; many mechanical switches can easily handle 10A currents.
- Potential problems with gloved fingers not actuating the button, or with water or nearby objects actuating the button.Â I suspect in most cases you won’t have these problems, but you should verify first, starting with the datasheet.
- High prices, typically $20-$100 (although a comparably sized mechanical button is typically $15-$30).
I found buttons from Schurter (Switzerland), APEM (France), Grayhill (USA), Texzec (USA), C&K (USA), EAO (Germany) and Barantec (Israel); there may be others, too.Â I think it’s interesting that almost all of these companies are either European or American.
There appears to be a limited market for this switch type; several companies have dropped lines soon after introducing them, and ITW Switches sold its ActiveMetal line to Texzec.Â I’ll mention some of the “missing in action” lines below.
So here are some of the more interesting switches I found, sorted by sensing type:
Piezo Electric Buttons
- Schurter has the PSE line of piezo switches, available in 16 mm, 19 mm, 22 mm, 24 mm, 27 mm and 30 mm sizes.Â Cases are made of plastic, anodized aluminum, or stainless steel.Â Illumination options are none, spot (1 LED), and ring.Â Prices range from ~$20 (CSE 16 plastic), ~$25 (CSE 16 aluminum), ~$45 (CSE 16 stainless) and up.
- Grayhill has the 37F series of piezo buttons.Â Cases are aluminum, and prices start ~$20.
- APEM has the PBA series, available in 16mm, 19mm, and 22mm bushing sizes, with and without illumination, and with anodized aluminum or stainless steel cases.Â Pricing starts >$30.
- Barantec has a wide range of piezo buttons in 16 mm, 18 mm, 19 mm, 22 mm, and 27 mm sizes encased in aluminum or stainless steel.Â Illumination options are none, point, and ring.Â Barantec only sells direct in the US.
- C&K had the KP series of piezo buttons back when they were part of ITT Canon, but they are no longer available.
- Capacitive buttons use a sensing technique similar to capacitive touchscreens.Â They can have problems with gloved fingers; however, Atmel claims that many gloves (including typical household, medical, and clean room types) should work fine.Â The buttons can often work through a thin non-conductive layer such as glass.
- Schurter had several lines of capacitive switches, including the CSE16, CSE 15 uG and CSE 25 uG.Â The CSE 16 models were round metal switches, while the uG models were designed to be used under glass.Â Mouser still has a few CSE16 switches left at >$90.
- EAO had the Series 75 capacitive touch buttons, but they are no longer available.
- APEM has just introduced the CP line of capacitive buttons; as far as I can tell, they are not yet available.Â The CP line will be available in 16 mm, 19 mm, and 22 mm sizes with anodized aluminum cases.
- Texzec‘s ActiveMetal buttons use ultrasonic energy trapped in resonant cavities. Â Available materials are stainless steel, aluminum, plastic, and zinc alloy.Â Sizes include 19mm, 22mm, and 30mm.Â As far as I can tell, Texzec has no distributors; however, Newark is selling the last of the ITW ActiveMetal buttons for ~$35 (22mm, zinc alloy).
I haven’t seen any metal ones, but there are some plastic models, such as theseÂ from Banner Engineering.
November 10, 2011 No Comments
This was supposed to be a quick post on one piece metal buttons.Â But it’s spiraled totally out of control, zooming past one post before finally settling down, I hope, on three posts.
I first researched metal buttons because I needed an ESD-safe button, and I couldn’t find one.Â Plenty of buttons have specs for ESD immunity, but I needed one that wouldn’t cause ESD (Electro-Static Discharge).
ESD can create a high voltage spark which can kill nearby sensitive electronic circuits.Â Everything close to the ESD-sensitive part needs to be either conductive and grounded or dissipative (material with resistance of 10^6 to 10^9 ohms/square so current will flow, but not too rapidly) and grounded.
Normal plastic is especially bad, because it is an insulator, and can be tribocharged: friction caused by rubbing the plastic part can create a large static charge.Â You can get dissipative plastics, but I don’t know of any buttons that use them.
Anodized aluminum is also an insulator; for an ESD-safe aluminum part you have to use electroless nickel plated aluminum.Â For example, Banner’s ESD safety light curtains use electroless nickel plated aluminum for the bodies and static dissipative plastic for the optical covers (BTW, as far as I know, they are the only readily available ESD-safe light curtains).
You can’t reliably ground through a moving part.Â So if a button has a moving button, then the moving part has to be grounded with a ground wire as well as the stationery part.
While there aren’t any buttons that are advertised as ESD safe, there are some that might work.Â What characteristics would help?
- Be able to ground the both the body and the actuator.Â A single piece, non-moving body is ideal if it can be grounded and is conductive or dissipative.
- Everything that an operator could touch must be made of conductive or dissipative materials such as stainless steel.Â If the button is illuminated, the plastic lens would have to be made of dissipative material.
So what are some possible solutions?
- One piece conductive metal buttons, such as a Schurter 1241.2611 PSE16 16-mm stainless steel piezoelectric button (~$45) or a Texzec T01-012203 22-mm stainless steel ActiveMetal ultrasonic button.
- Two piece conductive metal buttons such as a stainless steel vandal-resistant pushbutton (available from Schurter, ITW, and many others).Â As noted above, you’d have to figure out how to ground both pieces.
- Use an ESD-safe cover: cover a regular pushbutton with a fixed body that captures a moving part (to depress the button’s actuator); the cover parts have to be conductive or dissipative.Â One advantage: if you use a clear, dissipative plastic for the moving part, you can use an illuminated pushbutton underneath.Â This ESD-safe cover will probably cost substantially more than the pushbutton.
- Spray on anti-static spray.Â Although anti-static spray should help short term, I’m skeptical that it will continue to work well for a substantial period of time.
All of these possible solutions would have to be verified: you will need to verify that all external parts of the button are grounded and that the button will conduct or dissipate any static charges.
November 7, 2011 No Comments