Hi Guys,I have some Ex aircraft rotary encoders which I cant obtain datasheets for. Im flying blind trying to find the pinouts for +5v,ground, Output A etc. Ive tried the continuity method and I get a response But I have no idea how this works with encoders so I dont want to add +5v to the wrong pin and blow the internal led. Any help would be great.ThanksGaz

Hi Gary,Are there any manufacturer identification marks on it? Any part numbers? Can you post a picture or two?Mikewww.mikesflightdeck.com

Hi Mike,Part numbers can be seen on the large Oakgrigsby and small Grayhill. The small OG P/N 837-2008-030The large OG encoder is a tricentic so has 28 pins in total. Lower deck is 5 pos rotary switch, Middle deck it encoder, top deck is non turn pushbutton. Ive been able to get continuity on pins 1 and 7.The smaller OG is an encoder with push switch with 12 pins in total. Ive got continuity on Pins 2 and 7Cant find continuity of the switch when pressed on either of these.The small Grayhill is just an encoder but I cant find continuity on that one at all.Gary

Gary,Optical encoders won't give good continuity readings except for switch contacts or shared pin connections like multiple ground pins.It does seem likely that you have optical encoders. The Grayhill 61 series is. Oak Grigsby currently makes an OE2 series. I think the "OE" on the encoder refers to an earlier optical encoder series.I was unable to find datasheets on any of the units. However, I suspect you have redundant circuitry encoders similar to the Grayhill 61Z256 type. You might try wiring the small Grayhill encoder assuming it is configured like the 61Z and see how it behaves.The fact that you cannot get continuity from the push switch action may indicate that it is also an optical type switch with an open collector transistor output.Are these sealed units that cannot be opened for inspection?Mikewww.mikesflightdeck.com

Hi Mike,Sorry for the delay in getting back to you, just had to wait for the chance to buy some pullup resistors.Ive got the small Grayhill rotary working. Wasnt the same pinouts as the 61Z version. I used the trial and error method but dont really want to do that with the Oakgrisby encoders. The units arent sealed so I pulled one apart.(quite amazed at the simplicity of them)Looking at this pic are you able to tell which pin is ground, +5v etc.Thanks for trying to help me with thisGary

Gary,Symmetry suggests it's a dual circuit encoder. If so, There are likely 4 connector pins with signals on them. They should connect to just one device pin each. There should be 2 power pins, each connecting to 1 or 2 resistor pads. Finally there should be a single ground connector pin which should have connections to 4 device pins.Can you determine what the traces on the inside surfaces of the two boards connect?Also, are there only 3 connections between the two boards? I only see 3 through connections. I think there should be at least 4: power, ground and two signal. (At least, if it is indeed a redundant circuit encoder.)Mikewww.mikesflightdeck.com

Mike,I can only see it the same way as in the pics. I can only see 3 connections as well. I may pull the internals apart of the smaller encoder to have a look. Im not really concerned if this one doesnt work if I stuff it up as its easily replaceable with a normal encoder with pushbutton.Gary

Gary,Can you use an ohmmeter to check where those three input pins connect?Mikewww.mikesflightdeck.com

Hi Mike,This is where all of the pins connect. Am I right to assume then that pin 7 is the +5v as those two small metal bits would be the resistor blocks you mentioned earlier?Gary

Hi Gary,Yes, I think it likely that it's a power pin.I must admit to not having a wealth of ideas about the other pins as yet. Perhaps it's brain fade caused by spending the past several hours working on college financial aid forms for one of my daughters."Enter amounts as listed on your 2003 federal tax form (yes, 2003). Please note application must be submitted before Jan 15. Also note financial aid office is not responsible for any homocidal or suicidal urges/rages which may be induced while attempting to complete this application."I'm still mystified by only seeing three connections between the two circuit boards. Can you check for continuity between the remaining round component pads and connector pins? Most of them have numbered connections, but there are a few that remain unknown. (The linear groups of three and four round pads that presumably are where the LEDS and photo-sensors are mounted.)Mikewww.mikesflightdeck.com

Hi Mike,LOL..those college forms sound like a huge headache. As for the pins, I get continuity on those pins directly after the bottom edge of the resistor blocks to the first pin which you can see the track leading to. The middle has nothing and the two pins on the other side between 1 and 2 have nothing either.Is it safe now do you think to use the trial and error method using pin 7 as the +5v?Gary

GaryI kept hoping the girls would just marry into vast wealth and put off college. Oh well.Looks like trial and error. You might put a 100 ohm resistor in series with the +5 during the testing to limit the max current.Mikewww.mikesflightdeck.com

Mike,I tried both the Oakgrigsby encoders but it was no good Im afraid. Matt Ford suggested that this may be the case as he had to get a custom endoder chip made to suit his Grayhill one due to the different wave output. Was hoping these ones would be different.Im going to make a new shaft to suit the small Grayhill one which works and put it in place of the OG in the unit. Will workout fine ;-)Thanks again for you help. I wish I could have bought better news.Gary