pmlogg

Alan Thanks for that explanation and for doing more drawing for me. I have clearly not drawn the DPDT switches correctly nor explained them. The two I have are actually 3 position with the central one having no continuity. That's what I meant by "off". I suppose that the motor switch could have been a more basic two position switch as with the main switch at off there is no power flow anyway. On the connections to battery's 12V- this comes back to my problems of interpreting some of the example diagrams accessed via Lesvedome e.g. https://github.com/tonygilkerson/astrobagel/wiki/Observatory-Automation-with-LesveDomeNet and http://eplumer.blogspot.com/2010/01/observatory-gets-automated-dome.html which show more direct contacts with 12V- than just ground. What I need to do I think is trace them all in my head to see that they are essentially all just ground connections. Physically however what is that connection, if it's not to the battery's 12V-? In buildings there are ground straps to earth but the rotating part of the dome is essentially insulated from earth by the plastic rollers on which it moves and the rubber tyres on the motor drive roller and guide roller which are in contact with the non-rotating walls. So even the metal housing of the Pulsar/Rigel system is not a true ground. Thanks Peter

Alan Just noticed that I've still shown 3 x 5K ohm resistors; I've corrected to show 1K ohm. Thanks, Peter

Hugh Thanks, I'll put it back. Peter

Alan Re-reading your post, should I still have a link from DC- on the relay board to one of the GRD connections on the VM110? Thanks Peter

Hugh and Alan Many thanks for the fault finding in the circuit so quickly. Below I have redrawn, using my overly-complex layout as I have it on the computer as an image. I've drawn in a connection from the battery 12V- to DC- on the Relay Board. I've removed the DC- on the Relay Board to GND on the VM110 and also the 560 ohm resistor. I've changed the wiring for the NO and NC on relays one and two, in compliance with Hugh's board, putting them on the opposite side of the diode from where I had them placed before. I also reversed the battery symbol. I drew in but then removed an extra connection from the 7ah battery 12V- to NO1 and NC2 as they seem already to be connected to 12V-. Are those the GND connections that you think I need or are we talking about a separate ground line, e.g. to the metal plate that forms the housing of the Pulsar/Rigel system? If so should the GND on the VM110 also be connected to that point? For the moment I've left in the double pole switch to the 7Ah battery because otherwise there would seem not to be any 'off' position. In my diagrams I've shown the 12V charging socket which needs to remain live for the solar panel to maintenance charge the 7Ah battery. Would it not be better to isolate the two rotation circuits when not in use with a switch? Concerning the Raspberry Pi to VM110 connection, that is via a USB to USB micro cable. Not sure how I check grounding of that, that USB micro socket is the normal power in to the Raspberry Pi and I've not spotted any other GRD connection point on it. Thanks, Peter

Alan Good stuff! I'll make a start on wiring up tomorrow night. Thanks, Peter

Alan OK, like this? From another EM14 user I've read that with 5V I need to add a 560 Ohm on the + line into the encoder. I've drawn that in too. Thanks, Peter

Alan Connected as you suggested no click and no illuminated LED from the relay. So, should it be the 5K relay in the circuit as shown, or a different value resistorand/or one on the way into each of the three IN+connections?

Alan That's great. I'll do that what you suggested tonight and report back. If all is well after tonight's testing I'll aim to proceed with making the wiring loom. Drawing circuits is not something I normally do. Using the images rather than pure diagram was really just to help me when I come to do the connections. There are a lot of crossing wires which I don't like. There is also still some mechanical work to do. My sensor box needs spring tensioning as it in one quadrant the encoder's sensor wheel was coming out of contact with the dome rim. I've prototyped that using bits and pieces that I had lying about which worked fine. I've ordered stainless equivalents, some drilling, then adjustments will be required. Hopefully, thanks to the help from you, Hugh and others I may have a working system soon. Thanks, Peter

Alan OK, that's tonight's task. Back to the 12V- connection question. If the 12V- connections to NC1, NO2 and NO4 are for circuit protection should be kept? What about the 12V- connections to NC2 and NO1, which are not diode protection. Are they OK as drawn? Once the connections to the relay board are confirmed I hope to move on to doing a trial wiring up of the system, using a little 12V motor as a substitute for the dome motor and, for the moment, skipping the inter-connections to the Pulsar/Rigel legacy system. Thanks Peter

Alan and Hugh I went back a stage as I had not connected 12V+ to DC+ for the testing over the past evenings. I've now done so. I get the click now and the continuity checks OK, as suggested. However the voltage across the resistor is now 8.06V which is higher than the 4-6V figure suggested. So, does that mean that I do need to have the resistor on each of the IN+ lines? I am though now confused about the 12V - supply line. When I follow the diagrams that I did and posted, to me they show a direct connection to the VM110 ground, N01 and NC2. It also shows a connection through a diode to NC1, NO2 and NO4. Those connections were copied from the first diagram I posted, which I'd downloaded, showing the ELK single and double relays. If those connections are wrong what should 12V - be connected to? Thanks, Peter

Alan and Hugh Thanks for your two replies. I will have a go with that test when I get home. Hugh, looking back at the newest iteration of my circuit diagram I have: 12V+ connected to the 3 IN+ terminals, DC+ and COM4 on the relay board and to the brown lead on the Hall Effect Switch 12V- connected to Digital Output Grd on the VM110; NO1, NC2, NO4, NO2 and NC1 on the Relay board. I hope that is correct. Thanks, Peter

Alan So, if no click when testing without the in-line resistor on the 12+ into IN4+ and with IN4- (Relay 4 is the trigger relay) connected to ground then I do the continuity check across the relay outputs of Relay 4 and and should expect to see continuity between COM4 and NC4 and no continuity between COM4 and NO4? If I do not get those indications during the continuity check what does that suggest I need to do? Thanks, Peter

Alan I used a 5K resistor and got 4.65V, no click that I could hear though. So, I presume no resistors needed after all? Thanks Peter

Alan I had my reply written but not sent - so when I pushed the submit reply button it had not come in yet. I'll get my bag of resistors out now for that further testing. Thanks Peter

Hugh There was no difference in the readings on any of the 4 relays so I guess that the resistor(s) is/are needed. Thanks Peter

Hugh Thanks for that. I do have a multimeter, in fact I've just bought a new one as the continuity switch position on my old one has become intermittent. I will give that measurement a try tonight. Thanks Peter

Hugh and Alan Unfortunately no documentation came with the relay. Last evening I tried what was suggested. An LED illuminated on the relay board but no clicks. I measured voltage across the relay's outputs and did not get anything. When adding the resistor, do I need to add one on the line into each IN+ connection i.e. 3 resistors in total, or could it be in series before splitting off to the 3 relays? I've done another version of the wiring diagram, leaving off the pull-up resistor for the Hall Effect Switch, adding the fuse on the 12V+ line from the battery and adding 12V+ lines into the 3 relays, but with one resistor as above. How does that look? Thanks Peter

Hugh and Alan Thanks for that. I'm away in the Highlands for the weekend (no clear night sky in case you wondered) but when I get home tomorrow I will try that on the relay board to see what happens. I do have a pack of resistors should I need them but hopefully not as so far it just three few diodes that are in the way of simple terminal to terminal connections. I have a small project board to mount them onto for connection into the circuit. Thanks, Peter

Hugh and Alan Thanks for that extra guidance on the VM110 and connections. I think it has all sunk in now. While waiting for the relay to arrive I've been concentrating on putting together the box which houses the Bourns encoder and incorporates the Hall Effect switch; also making a mount for the home position magnet (going to try that first but can change if not accurate enough. The relay didn't arrive until 9p.m. last night - other commitments mean I probably won't be able to do trial wiring etc. until next week. Thanks Peter

Allan That's great, taking out the resistor is ideal, as is not adding any other components. The relay has not arrived yet; when it does I can try connecting it all up. Thanks Peter

Alan and Gina My Hall Switch claims to operate between 6 and 36V. So is not 5V too low for it (even taking out the resistor) and conversely 12V too high for Dig In 2? Currently the only 5V into the system is from Powerbank to the Raspberr Pi, via usb. Are you suggesting running a separate 5V (e.g. cut usbfor cable) for the Hall Switch? (but again that then falls below the 6V minimum. As an alternative could the circuit stay as now but add a buck converter - 12C to 5V- on the black line, beween the switch and Digital Input 2? Thanks Peter

Alan Thanks again. A problem could be that the Hall Switch is rated as using input of 6-36V, that's why connecting to the 12V seemed to be a good idea. But if the pull-up is not needed and the supply is 12V would not the signal still end up being 12V? Connecting a resister across the 5V line from the Powerbank would not be easy as it is delivered by a cable with USB connectors at both ends. So, how to supply 6-36V without the signal in the board exceeding 5V? Do I need a 5V rated Hall Switch or perhaps even a plain old Reed Switch? Thanks Peter

Allan Thanks or that. I'll add an in-line fuse. Thinking about it there is one on the original Pulsar board - for just that reason. I can see what it's rating is. Luckily it's never blown as changing it would be awkward. Thanks Peter

Allan Thanks for spotting that mistake with the resistor connections. I did know the correct positioning but drew it incorrectly. I've now changed it. The Hall switch needs 6-36V. When I first got it I tested it using 12V supply and no resistor. It did not produce a signal. I then added the resistor and it worked. So, that's why I've drawn it in. I will try it without and see. All the better if it can be left out. The Dig Out3 to Dig In3 comes from other example circuits. I don't really know what it is supposed to do. I'll need to look back through emails etc. to see if I can find an explanation. Again if I can get rid of it all the better. I presume I need all of the 3 diodes shown. I bought 10 so if needed elsewhere in the circuit they are available. Once the relay board arrives next week I can get down to testing it. The rest of the components I have already. Thanks Peter