Hi
I need an angled rotary encoder, PCB mounted, 12 pulses per rotation is okay.
The problem is that the height above the PCB must be lower than 6.4mm
Could be something like this, however it has 7.25mm above the PCB:
Anyone know of a suitable device? (it's for high volume, so no DIYs)
Thanks
Klaus
US Digital has some pretty small mag encoders, but I don't know if they're as small as that.
Cheers
Phil Hobbs
Perhaps mounting the encoder flat onto the PCB, and use two bevel gears to drive the encoder? If that's acceptable, use an SMD rotary shaft encoder such as: More:
Unfortunately, their smallest models, similar to the Alps encoder, are about 7.4 mm above the PCB.
You could build up something like the rotary encoder in a common computer mouse. Attach the encoding wheel to the drive shaft and use an optical interrupter mounted on the PCB.
Last resort is to mill a rectangular hole into the PCB, insert a packaged shaft encoder into the slot, and solder the leads on the opposite side of the PCB. That should drop the encoder height 1.6mm but will probably require hand insertion and soldering.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
EC05E/EC05E1220202.html
If the volume is high enough then "DIY", or at least "custom manufactured" may not be such a bad thing.
How about one of the surface-mount hall-effect shaft angle sensor, with a snap-on molded plastic housing containing a shaft with a magnet?
-- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
Yech. If he's going to roll his own, I would make the shaft from translucent plastic, illuminated with an LED (which doubles as a pilot light). For a large diameter shaft, mill or cast two rings of slots spaced for quadrature around the shaft. For a small diameter shaft, use tiny bumps instead. Two photo detectors on the PCB and you have a rotary shaft encoder. If you don't like the customized shaft, mill the holes in a plastic sleeve the fits over the shaft and illuminate the edge of the tube. Don't forget to cover with cardboard so that it works when the covers are off.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
I've seen capacitive sensors used for this sort of thing, too.
Thanks
I checked out their product range, quite nice parts.
I will be using it for human userinterface (scroll wheel), so we need to keep the price low, and the US Digital types did not seem to have any in the really small outline size.
Cheers
Klaus
Nice parts, but as you statet not quite small enough :-(
It's for high volume, so we cannot resort to unproven techniques or not optimized for DFM
Cheers
Klaus
Sounds intriguing, we have a tight deadline (who hasn't), so I do not think we can resort to this
Cheers
Klaus
Variation on this: Mill a rectangular hole into the main PCB. Make a little PCB (1 x 2 cm maybe) with the hole pattern for the encoder in the middle and holes for pins around the edges. Install encoder into little PCB and solder. Install pins on main PCB and solder. Then put the little PCB on the bottom side of the main PCB, with the encoder sticking up through the rectangular hole, and solder the pins to the little PCB.
This does assume that you have a little more than a PCB thickness worth of room under your main PCB. It takes more material than Jeff's way but might be marginally more acceptable from a DFM point of view: you don't have to bend the encoder leads in strange ways, and you might be able to pick-and-place the little PCB. On the other hand, it *is* another PCB to make.
Matt Roberds
Yeah, had the same thought. The same principle when soldering planar transformers directly onto a PCB
Cheers
Klaus
Can you use this? Reflective encoders.
Jamie
[for a scroll wheel]
Can you use capacitive touch instead?
-- Neither the pheasant plucker, nor the pheasant plucker's son. --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
you only need one ring of slots for quadrature just mount the second sensor out of phase from the first by 1/4 of the slot pitch
-- Neither the pheasant plucker, nor the pheasant plucker's son.
hth
- Michael Wieser
That's nice, however very expensive
Cheers
Klaus
Yes, we could.
Then we need to order a fixture for the axis, but that can be done quite cheaply
Cheers
Klaus
Did you ask ALP if they can make 3mm parts instead of 4.5mm? ( SHaft offset )
The biggest point to me is that if the volume is big enough, rolling your own may be the cheapest solution.
Of course, if your volume is big enough, then calling up your manufacturer of choice and using that anticipated sales volume to arm- twist _them_ into rolling one up for you is a good move, too.
-- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
When I built a few prototype encoders for a "really cheap radio" proposal, I found it difficult to mount two sensors in quadrature around a shaft. It was much easier (and cheaper) to use two photo detectors inline on a single PCB parallel to the shaft, and quadrature stagger a 2nd row of slots or detents around the shaft. On a standard
1/4" volume control (plastic) shaft, I was able to cram 12 slots around the circumference at roughly 0.1" spacing. The milled slots were nice because the light going down the length of the shaft would diffuse through the rough sides of the slot sufficiently for the photo detectors to pickup the light. I would have use conical holes except the required depth weakened the plastic shaft excessively. The biggest headache was adjusting the detector sensitivity so that it would not pickup light from slots on the opposite side of the shaft.-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
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