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Alan and Hugh Sorry for the delay in responding - Father's Day activity. It will be later tonight before I get down to your suggestions. Other than shortening the cables and changing over from the temporary connections to the test motor and power the boxes are ready for mounting. This is a picture of the components. By the Encoder box is the magnet ready for mounting. Out of picture are the test motor and battery. The connectors - usb, DB9 and XLR are fitted but will need to be removed and refitted during the mounting onto the observatory wall. Thanks, Peter

Alan OK, I'll try that in the morning. The VM110, Raspberry Pi and Relay board are all now mounted for the enclosure. Once I shorten as many connecting wires as I can it will look at lot tidier. That will be an opportunity to check the connections again, although I did a bit of that this evening - no change on the performance though, same issues. Thanks Peter

Hugh and Allan A couple of anomalies. In K8055_Demo (not Dome Demo as I wrongly wrote before) twice the motor has stuck on, not reacting when I deselected the digital outputs. had to disconnect the power In Lesvedome I twice got the motor to react in one direction, but then got stall in the other. Once I was able to get CW and CCW but when I tried to repeat that success it was back to stall in both directions. That time when I got both directions but then stall the next the timer interval was set to 20msec. Thanks Peter

Alan and Hugh Yes great news indeed - thanks again for all your help. However if it turns out that the accuracy of the Hall Effect Switch isn't good enough, then I can relatively easily switch to the opto-switch - so I'll keep the 3009 model. Inevitably there were going to be wrong turns and bits bought that would be superseded. The main one is probably the Compute Stick but I can find another use for that I'm sure. Then there was the very cheap encoder and twin-relay board which I really only got for experimentation. The little 12V motor was a good buy as it has been much easier to bench test with it than anything bigger. One cheap XLR chassis connector was a bad buy so has been replaced. An enclosure that I bought for the encoder had not been thought through - fixings on the wrong side and the stainless spring to keep the encoder wheel in close contact is a bit too short/strong. I have a non-stainless one that will do for now. The connections you've listed Hugh seem correct in the layout. I will re-test Lesvedome with those settings. As I wrote last night I've not tried changing the version of Lesvedome yet. I was confused because the error message came without any sign of the relay clicking first. That's the priority but also I need to drill for standoffs and mount the components onto the board I've otherwise prepared for them. I also need to drill/cut the enclosure for the 3 cable entry points: DB9 for the connection to the Encoder Box, 4-way XLR to the motor and power switches and usb for the power in from the powerbank. I also need to tidy up the cables, a lot of which can probably be shortened. Oh and also properly fit the 10K resistor and diode which I only did a temporary job on last night. We have family visiting today but hopefully later on I'll be able to crack on with much of that. Thanks Peter

Alan Diode and Resistor in - Hall Switch working on the 5V supply. LED off until magnet approaches - then the LED illuminates and Counter 2 adds one to its count - Perfect. So all seems to be working under Dome.exe but Lesvedome still isn't happy for some reason. I'll need to remind myself of the direct quote but essentially it does not slew when told to and disconnects itself. I've not yet done the uninstall of the most up-to-date Lesvedome to revert to the older. Perhaps that should be my next step. Thanks Peter

Alan Thanks for the thumbs up and for the suggestion/diagram for the Hall Switch. I will definitely give that a try as the Hall Switch is otherwise all mechanically fitted and wired in. I've just finished wiring in the voltage regulator and testing that the relays and encoder were still working - which thank goodness they are. It is currently feeding 5V to the Hall Switch and the LED is still on but is dimmer - the 10K is though out of the loom just now but I can easily put it back in. I'll let you know what happens with that - I'll initially try it at 5V as an experiment before switching it back to 12V. Thanks Peter

Alan and Hugh In total I've taken out the diode and 3 resistors on the 12+ lines and added the diode onto the IN4 DO2 line and that has sorted that out! When I power up only the relay board (not individual relays) illuminates. When in the dome.exe programme I select Output 1 I get motion in one direction and when Outputs 1 and 2 are active I have motion in the other direction. And that both by direct usb connection and when connected via the Raspberry Pi's virtual usb link. I'm going to add back in the encoder to check its still doing what it's supposed to do. I could even try the Hall Switch but I can't see why the changes I've made should help that. Annoyingly Fedex has messed me around yet again today. I'd ordered my 3009 optical sensor from TME for £1.47 plus post plus VAT and it was due to arrive today. Unfortunately my wife was out and instead of putting the package through the letterbox (it should be pretty small) they took it all the way back to their depot 40 miles away. Apparently this valuable parcel had to be signed for so I won't see it until Monday! A similar thing happened to me with parts coming from Mouser in the US - the Bourns connector cable being one of them. They missed us on the Friday before the bank holiday and took not just the Monday off but Tuesday too, so 2 days crossing the Atlantic then 5 days delay getting across Scotland, hopeless. I'll not let that spoil the moment though. So, many many thanks for helping me to get this far, including the diagrams, explanation and fault finding. Fingers crossed that the two sensors now do their bit - if so I might even manage to get it up and mounted in the Dome for a trial run within the next week. I will send photos once the components are secured etc. Thanks Peter

I certainly have not regretted it. On size, the advice is to avoid building too small. However I would have thought 12' x 9' would be fine and meet that 10m2 requirement. My dome is a 2.7m (8.91') diameter which I find is OK even with a fairly long refractor. That works out at less than 5.75m2. Even a 9'x9' shed would give 30% more space than I have and of course circular walls are not the best for desks and storage.

Alan Thanks for that explanation as I would not have been up to explaining why it could/should work. As that may be a solution, and I have diodes to hand, I'll try that before doing further testing. Thanks, Peter

Hugh and Alan Further to my last I've just found Edward Plumer's more detailed explanation of why he deviated from the Charles Harrow circuit: "My main modifications [from the Charles Harrow circuit] were the inclusion of a motor-speed control board and to alter which triggering mode to use on the ELK boards since some forum users were having problems with the ELK924 triggering all of the time. Here is a post I put on the LesveDome Yahoo group regarding the triggering problem: The root problem is that the ELK board in "sensitive mode", triggers on a very small current injection into (T-), small enough that the pull-up circuitry in the input section of the 8055 can source this current. Note that the relay boards are powered at 12V and the input of 8055 is only pulled up to 5V. I reasoned that from the ELK ckt point of view, the 5V pull-up actually look "low" enough to to act like the input to the relay board has been pulled down and negatively triggered. ... There are 2 alternative solutions: (1) Force the relay board to act as a voltage switched device - This was my approach. Ensure that the 8055-Output2 has to pull the boards negative power rail down to GND along with the trigger input. Minor current flowing into 8055-input logic will do nothing because the circuitry in the ELK board is not "grounded". (2) Shut down the inappropriate current path - This was Joe's approach. The diode between Out2 and In4 only allows current to flow FROM In4 TO Out2. Thus, if Out2 is pulled to 0V, current can flow from In4 to Out2 and be detected by the 8055 as an input signal. However, If Out2 is not enable, the diode prevents current from exiting the 12V circuit of ELK input, into In4, through the pullup resistor, to the 5V level." Perhaps this was a specific issue with the ELK relay boards but might it also be with the one I'm using? Thanks, Peter

Hugh and Alan, I was looking at the Lesvedome documentation just to check about assigning a different Digital Output rather than No. 2 but I came across this paragraph which referred to the Edward Plummer circuit diagramme in the Lesvedome instructions: "ELK924 [relay] needs to be triggered in "insensitive" mode, (2) reverse-current protection diode D0 prevents the DI4 circuit from triggering ELK924 all the time. The relay that is referring to is one on the connection from Digital Input 4 to Digital Output 2. I initially had that diode drawn in on the basis of the Edward Plummer diagram but you correctly pointed out Hugh that the standard circuit from Charles Harrow does not have a diode, that your working system does not include the diode and that the 0.5 to 1.0V drop caused by the diode might cause a problem. However might wiring in a diode be worth a try just in my variant circuit? Thanks, Peter

Alan OK, that's a plan for Friday night. Many thanks, Peter

Alan The measurements that you suggested: DO1 to Grd: DO1 on = 0.68V DO1 off = 11.7V DO2 to Grd: DO2 on = 0.70V DO2 off = 8.25V So DO2 off not as high as DO1 off but still a lot higher than DO2 on. I looked at Lesvedome and couldn't see any way of selecting which Digital output to use. Thanks, Peter

Alan Yes, when DO2 is connected as normal and the connection to the 12V battery is made, relays 1 and 2 click and their LEDs illuminate. The LEDs stay illuminated. When the VM110 is disconnected other than to the computer, selecting each of the outputs causes the led to come on and they go off again when deselected. The voltages 0.82 etc. were recorded when the VM110 was only connected to the computer and the relay board was not powered. The voltages in the table were made with DO1 and DO2 connected and also DC- on the relay board to Grd on the VM110 and the relay board was powered. They were switched off and on as per the table column headings. I'll go now to measure at DO1 and DO2. I will have to look to see whether the Lesvedome programme allows a choice of which Digital Output is used. I don't think it is something that I set when putting parameters into Lesvedome. Thanks, Peter

Hugh I've done the test of the relay with DO2 at the VM110 disconnected. Before I did so I made the changes Alan suggested - basically taking out the diode and resistors from the positive line coming from the 12V battery. When I touch the disconnected wire to DC- on the relay board relays 1 and 2 activate. I've checked the wiring from DO2 and there is continuity on all the wires indicated in the diagramme. One thing that I have not reported is that when I apply 12V from the battery relays 1 and 2 both activate and their LED's illuminate and stay on. Relay 4's LED does not illuminate until, in dome.exe, I select Digital Output 1 or Digital outputs 1 and 2. So, I assume that then all 3 connected relays are active at that point - but rotation continues in the same direction either way. Does this suggest that perhaps my wiring diagramme, noting what Alan has found about his identical relay board, needs alteration? I don't know how I further fault find VM110. Thanks, Peter

Alan Thanks for the diagramme. If for the moment we assume that my relay board is OK, could the un-needed resistors, or anything you've now found out about the board be responsible for the voltages that I noted in the table, and for the seeming lack of action by Relays 1, 2 and 3 (I swapped connections from 2 to 3 to see if it made any difference). I'm just about to start the additional testing of the relay board that Hugh suggested. I could try taking out the diode and resistors on the lines to the IN+ terminals and DC+ (the Hall effect and encoder are disconnected at the moment anyway). Thanks, Peter

Hugh OK, that's what I'll do. The 4009 is due to arrive first so I can play with it first, including working out the mechanicals. I can then swap in the 3009 when it comes. Thanks Peter

Hugh Thanks for the guidance regarding the Optical Sensor - a very good point about not having the strip, or equivalent mounted too firmly, i.e. not a screw as I suggested. I note that the layout of the sensor itself looks different from what is set out in the spec sheet and also that it has 4 wires rather than 3. It looks as if the 4th is ground wire; would that be right? Thanks, Peter

Alan Thanks for that investigation of the Relay Board. Do I still need the Diode protection of the three IN+ connections? I presume I still need the Diode on the ground/negative line to NO1, NO4 and NC2. Thanks, Peter

Just spotted that I'm still showing the wrong resistors.

Hugh and Alan I've updated the circuit diagramme to add the Voltage Regulator, replace the Hall Effect Switch and remove the usb power link from the Raspberry Pi to the Encoder. I've put the Encoder and Voltage Regulator to ground on the VM110, I presume that's correct. Does the Voltage Regulator need protection from the diode on the positive line? The instructions suggest it is protected from reverse polarity. Thanks, Peter

Hugh In your implementation of the Omron EE-SX3009-P1 as your Home Position Sensor what do you use to interrupt the beam? I see that the aperture for the optical beam is just 0.5mm wide x 1mm high. I reckon my dome rotates at around 4.3cm/sec if that matters. As the sensor will be moving, whatever I use to interrupt the beam will be attached to the dome wall, projecting inwards around 11.5mm according my drawing (scale on my computer is 10 pixels/mm). Might something as simple as a 2mm screw, aligned to be on the centreline of the sensor slit, work? The vertical positioning of the sensor in my drawing is not quite as it is was in practice when I was aiming to use the Hall Effect Switch. The static magnet in its housing had to be positioned so that its fixing screws were out of the way of the motor drive wheel as it moved along the outside of the dome rim, and the housing out of the way of the encoder wheel. The Hall Effect Switch was positioned accordingly and that will be the same issue affecting fitting the optical sensor and the object to break the beam. Thanks, Peter

Alan and Hugh That's great, it looks easy to use, even plastic sleeved so I won't need to secure it as another PCB. I didn't initially go down that route as it seemed easier to use a redundant usb cable from the Pi but now that I have both sensors needing 5V its a neater solution. Also, using the 'UBEC' means one less thing that's been sitting about.

Alan and Hugh Thanks for those explanations of the two types - I'd missed that differenced and wasn't helped by ads for the two types which gave the same description - so you can guess what happened. So, now having ordered the correct (3009) version I'll be adding the 4009 to my collection of unused parts. I doubt that it will come before Monday though. From what Alan read from the specs the maximum input voltage is 10V. Your suggestion of the buck converter reminded me that I have a switch mode UBEC that I bought years ago for a project that didn't go ahead. Attached is an image of it with the instructions. I looks like I can feed it 12V and output a regulated 5V or 6V. So I may use it to supply the Encoder too, and get rid of that butchered usb cable. I presume that should be OK? I've not yet tested though as I had to search around to find it tonight. Unfortunately my plans for the evening had to change - booking holiday flights etc. had to take precedence with just 10 days before we fly. Hopefully I can press on tomorrow night.

Alan Thanks for that. I'll not bother changing the power sources unless I need to. I've now ordered an optical switch - due to arrive at the weekend. I hope it can be implemented in a similar way to the Hall Effect Switch. Concerning the relay board, yes I have a 1K resistor on each line going into the IN+ terminals, all coming after the diode, as in the diagram. As Hugh has suggested I'll be aiming to check that part of the circuit tonight, along with the rest of his suggestions. I'm hoping that my soldering skills won't have been the cause of problems, although finding the source of the problems is the priority. Thanks, Peter