Dennis, if you have a "bare" PCB without solder mask, you might get a bit more contrast by staining the substrate with dye.
On Sat, Jun 2, 2012 at 10:28 AM, <ceen...@in-front.com> wrote: > I am making a batch of 1" diameter PC board wheels for use with the 75LPI > Avago AEDR-8300-1K1 quadrature encoder module. The module is a reflective > style and the PC boards are gold plated for reflective purposes. Plating > with gold makes for a very flat surface as opposed to HASL hot air leveled > solder which leaves bumps of solder and may not reflect straight back to > the sensor. > > > It's nice to hear that laser printed wheels cannot be "seen" with this type > of sensor. I'm going under the assumption that the fiberglass between the > gold traces is not reflective enough to mess with the sensor. Gerber > files are available for 75LPI and 36LPI parts if anyone wants a copy. I > created the geometry once then copied it radially times 100 or 50 > positions. Goes prett fast. A pic of the board is at: [LINK: > http://flic.kr/p/c9Y7Jo] http://flic.kr/p/c9Y7Jo > > > The same principle will work for bigger wheels. The 75LPI wheel comes out > to 6.67mil wide traces and spaces. > > > I'm working with DC motors in the 32mm diameter range. The DC motor has a > 72MHz ARM Cortex-M3 on the back of it, motor driver and encoder. Overkill? > Maybe, but in the end we'll have a PID controlled motor, USB port, > programmable current limit for torque control and also scalable in the > future for 3-phase brushless DC. > > > Dennis > > > > -------Original Message------- > > From: andy pugh > > To: Enhanced Machine Controller (EMC) > > Subject: Re: [Emc-users] Encoder discs > > Sent: Jun 02 '12 10:15 > > > > On 2 June 2012 15:21, cogoman wrote: > > > While I can see the need (sometimes) for a durable metal encoder > > > disc, and I have cut some out of .016" copper (was on hand, and never > > > got tested), I wonder how useful, or how durable laser printed > > > transparency film would be for many applications. > > > > It works perfectly, with transmissive encoders. > > > > I had two problems: reflective sensors and a mandatory 75lpi pitch. > > I tried laser-printing but I couldn't find a laser with a fine enough > > dot-pitch to not alias at 75lpi, and the sensor was equally blind to > > white and black. It needs shiny. > > > > -- > > atp > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
