symmetal

For the data connections (all the wiring to the VM110 board) you can use thinner wire like 22 awg as none of it is high current. Only wiring going to the relay board COM, NO and NC contacts, motor, 12V battery, fuse, rigel system, and associated switches needs to be of 16 awg or similar (ie. any wire that can be carrying current going to the motor.) Using multi-strand wire of a similar overall thickness to single core is fine. It's current rating is only slightly less that the single core and won't be a problem in your case. Alan

Wireless USB hubs don't exist because of the different bandwidth limits of the technologies. Depending on the Wireless standard used the maximum practical bandwidth (significantly lower than theoretical maximum) is around 25Mb/s for 802.11g, 100 Mb/s for 802.11n and 300Mb/s for 802.11ac (also called gigabit Wi-Fi because of the theoretical maximum of 1300Mb/s but not achieveable in real life.). USB2 has a maximum bandwith of 480Mb/s so even Gigabit Wi-fi would struggle with 1 USB2 connection when image downloading. USB3 mas a maximum bandwidth of 5000Mb/s so is totally incompatible with Wi-Fi. Alan

The diode between O2 and I4 on the VM110 I believe is there to protect the input, if the output voltage (when the output is turned off) is pulled up above above the maximum voltage the input can handle (which is 30V). The VM110 can drive 48V relays (or a load up to 50V and 500mA) and in this case the input would likely break down without the diode. As you are only using 12V relays this wouldn't happen so the diode can be safely left out and the O2 to I4 connection made with a piece of wire as Hugh suggests. Alan

Sorry, I didn't pick up on this point. You seem to have on/off/on 3 position switches anyway for the battery so that's fine. You still only need a single pole switch in the battery +ve connection as when that is in the centre 'off' position the battery is disconnected power wise. The battery -ve terminal can be permanently left connected to ground. You can if you wish leave it as you've drawn it and it will be fine. It's your choice. As you say the motor switch only needs to be a 2 pole changeover switch but if you're happy using the three position switch you have, there's no problem. Alan

It's just that png files, like jpg, display directly on the forum so don't need to be downloaded to view them. As Dave said, slight coma, predominantly bottom right. Better than the other RedCat images shown here. Interestingly CCD Inspector gave it a 'good' result with all four corners similar and the centre slightly out of focus. Probably not enough stars for a proper assessment as it only found 523 stars. Around 3000 or more stars are needed fairly evenly spread over the image give the best results. Alan

Peter, Yes, the negative terminal of the battery can be called 0V or ground, whichever one you prefer, and anything that is connected to the battery negative terminal can be called 0V or ground as well. Point 1: Correct Point 2: Correct Point 3: This grounds NC1 and NO2 which is what I think you meant to say and not NO1 and NC2 Point 4: Relay board DC-does need to be connected to a VM110 Ground, but it already is by they connection in point 1 as you say. Hugh was just confirming that point and not saying that a second ground is needed to the VM110 though it could have been interpreted that way. Point 5: Correct The raspberry pi 0V power wire on the USB cable to the VM110 would be connected to the VM110 ground terminals on the board itself which is how the EM14 gets its ground. When you plug the powerbank into the raspberry pi the powerbank will automatically connect its negative output terminal to ground too so no extra ground connections are needed there. Your drawing of the relay board connections do look the same as mine and Hugh's drawings. Alan

Treat the battery negative terminal and everything connected to it as Ground or 0 Volts. I assume all the equipment is fixed to the rotating roof so as you say there is no actual physical. connection to the earth for a true Ground connection. Ground in your instance is just a nominated point which you can call zero volts to which all the other voltages are referenced to. As your system has no physical ground connection you can't make any voltage measurements with your multimeter if you connect your black meter lead to a true ground like you will have in your home. So you have to nominate one voltage in your system to act as a ground for making measurements. The most logical is the battery negative terminal. Talking in terms of 12V+ and 12V- could imply +12V and -12V which have 24 volts between then. Calling the 12V- terminal 0V or Ground for convenience, removes any ambiguity in labeling. As your system is only 12V powered you don't need a physical ground or earth connection for safety reasons like you would with mains voltages. Ground and Earth are the same thing but it's more common to use Ground particularly with DC. From Wikipedia Alan

Here's the updated drawing with the amendments. Hugh's is much neater on showing the relay output modes. NO1 and NC2 are not connected to -12V, as they connect +12V to the motor when relay 4 is turned on. It's best to have 1 common ground terminal close to the 7Ah battery and connect the high current Gnds to that point (7Ah -ve, NC1 and NO2, Rigel 0V, relay board DC-). Also connect one of the Gnd connections on the VM110 to this common ground too. The hall effect Gnd can go to one of the other Gnds on the VM110 board. I'm sure the Pi USB 0V is connected to the VM110 Gnd on the board anyway but you can check that the azimuth sensor power negative terminal has continuity to VM110 Gnd when you've wired the Pi USB cable to it and the Pi is connected to the VM110 via the other USB cable. Using the double pole switch on the battery doesn't give an off position on the battery, as it's connected to either your new system or the Rigel System. A separate on/off switch wired between the charger connection and the changeover switch would provide a battery off, or else use a 3 position on/off/on switch instead of the changeover switch. Alan

Hugh, you're right. I missed off the motor ground connection. The junction between relay1 NC and relay2 NO should also go to ground. As this is carrying the motor current as you say it should be connected to the battery negative and not just go to a VM110 Gnd or similar. Wiring from the battery to the relay contacts and motor should be using thick wire (10A rated at least) while the wiring to the VM110 can be thinner wire as they are carrying much less current. Checking the encoder spec afterwards you're right that the 5V to it's power pin is what it needs. 560R is a bit high for filtering, 5R6 would be OK but it's not actually needed. Peter's drawing shows the Relay board DC- going to a Gnd on the VM110 and the battery -ve going to another ground connection on the VM110. The three Gnd connections on the VM110 would be joined together on the board so there is no need for all three to be connected together to Gnd externally, just one would do, but I generally always show all Gnd terminals as going to Gnd. I'll post an amended diagram later.

Peter, Here's a quick sketch I did of your circuit which may make the relay/diode connections clearer. I drew the Ground connections as ground symbols to save cluttering the diagram with lines. The ground symbols are of course all connected together in reality. There's also no need for a double pole switch to the 7Ah battery as all the Ground/0V connections can be left connected to avoid things floating when not used. The Rigel motor output connections may need to be swapped over depending on which way the motor turns to make it drive in the same direction as your new system. I didn't draw in the hall effect 12V wire as it would be a bit messy so arrowed the connection instead. Edit: It's worth checking that the USB 0V connection from the raspberry pi is connected to Gnd on the VM110 board. I'm sure it will be or things won't work properly. Also, I didn't notice on your diagram until I redrew it but the symbol you had for the 12V 7Ah battery was drawn the wrong way around. The long line is +ve and the short line is -ve. Corrected diagram posted a few posts down. Alan

Yes, that looks right Peter regarding the 1k resistors. If you want to put a 560R in the 5V to the encoder that should be fine. It could be just to reduce any noise on the 5V supply. Alan

Peter, OK, so the resistors from each of the IN+ connections to +12V are required. I would use 1k resistors if you have them. This would pass 4.5mA through the opto-isolator LED which is reasonable. Using your 5k resistors it would only pass 1.6mA (yesterday I said it was only 0.89mA with 5k resistors but got my sums wrong). A 1k resistor should measure 4.5V across it when the relay is operated, if you want to measure it. A 2k resistor would also work fine too. It's not that critical. As you found out it does work with 5k but I would use a lower value just to be sure of definitely switching the relay. 3 resistors are needed, 1 from each IN+ to +12V. Alan

Peter, The circuit as drawn should be correct. The diode where it is, protects the whole circuit and not just a part of it. Following the diode connections it is connected across the motor all the time which is what you want. Redrawing the circuit in a different way but keeping the connections the same would make it a lot clearer. If I have time I'll redraw it which should hopefully make it easier to follow. Hope the test goes well. Using a small motor for testing is a good idea, as if there are problems it shouldn't do any harm. Alan

Polaris is the worst star in the sky to sync on with an EQ mount as it's so close to the celestial pole that with a small polar alignment error of less than 1 degree the scopes RA could be any random value when polaris is centred. Also it could easily hit a meridian limit if the dec tries to go through 90 degrees and a meridian flip is needed. Moving in RA to try and centre polaris may also try to drive past the meridian and cause a limit error. CdC could well refuse to sync when the Dec is close to 90 degrees as it would cause more problems than it solves. Chose objects less than around 45 deg Dec to sync on for alignment purposes and you and CdC should be happy. Alan

Oooh! Okay, glad the relay's now operating. Yes there is a connection via the diode from 12V- (lets call it 0V or Gnd as that's what it is in reality) terminal to NC1, NO2 and NO4. But notice the diode is connected in reverse. The arrow on the diode symbol indicates the current flow direction when it conducts, so the left hand end of the diode (anode) has to be more positive than the right hand end (cathode) in order to conduct current. As the anode is connected to 0V it will only conduct if the cathode goes more negative than 0V which it can't do in normal operation. So in normal operation the diode is effectively not there and is an open circuit. The only purpose of the diode is to suppress any negative voltage spikes generated by the motor when the motor is turned off. If you follow the diagram the diode is actually connected across the motor terminals. It's an unwanted side-effect of suddenly removing the power from large value inductors which is what the motor is, in effect. NC1, NO2 and NO4 are connected to +12V when relay 4 operates to supply power to the motor. Relays 1 and 2 control the motor direction. To satisfy my curiosity and to test my initial thought as to whether it works like the ELK-924 with a separate + or - trigger. Remove the resistor from the IN+ terminal, but don't connect the IN+ to +12V. Just leave IN+ disconnected. Connect the 12V to the DC+ and DC- of the relay board as you've done and just touch IN- to ground (DC-) and see if the relay clicks again. If it does we don't have to worry about external resistors or any connections to IN+. The fact that your latest test drops 8V across the external 5k resistor implies that the on-board resistor is only around 1k2. If IN+ is connected directly to 12V then 8mA would flow through the opto LED, which isn't a problem as they will work with a wide range of currents. With your 5k resistor in circuit the LED is only carrying 0.89mA but it is still working enough to trigger the relay. It's possible the IN+ is intended to be connected to 5V logic switching if required rather than 12V. The LED would only carry 2.5mA if IN+ was from 5V which would work nicely. Do the test in my previous paragraph to see if it mimics the ELK-924 which will solve a lot of problems and report back. Alan

Hi JimothyC, Yes, there is significant coma (fan shape smears pointing towards the centre of the image) in the bottom right and some coma top right and bottom left. It's more obvious in the brighter stars but if you look closely the dimmer stars do exhibit similar 'smearing'. Here's the CCD Inspector plot showing the same. Ignore the curvature/tilt analysis as it's interpreting the coma as star errors due to image curvature and tilt which it isn't. Just another poorly aligned RedCat I'm afraid. Alan

On Hugh's behalf your +12V connections you mentioned are correct. The -12V however doesn't go to NO4, NO2 and NC1 and it doesn't on the drawing which is correct in that respect. Alan

Thanks Dave. Was only clutching as straws with the damp theory. I suppose the glass does get quite hot in use so maybe the temperature extremes are causing problems somehow. I did clean yesterday, the rear of the output side filter with Baader fluid so thought leaving it with desiccant would remove any water traces that might be lurking. Removing the orange plate doesn't cause any alignment problems as the mirror is held in its recessed location in the housing by the pressure from the foam pad on the orange back plate. The edges of the mirrored surface are quite scratched as the mirror presses directly onto metal but the mirror is larger than it needs to be so the scratches aren't in the optical path. Yes. They must be wondering what has caused this sudden request for filters. Hopefully mine arrives tomorrow.

Peter, I only suggested checking relay terminal continuity as a way to check if the relay may be working but you can't hear it click. When the relay is 'off' there will be continuity between COM (Common) and NC (Normally Closed) and when it is triggered 'on' there will be continuity between COM and NO (Normally Open). The COM terminal flips continuity between the NC and NO terminals when the relay is operated. If you don't get that we will have to start scratching our heads some more. It's difficult trying to analyse something remotely when you don't have a circuit diagram to work with, and you have to make educated guesses as to how it's actually wired. Alan

Same here. I'll try keeping the diagonal in an air tight food container with a couple of FLOs little desiccant bags when not in use, to see if it is moisture related but I'm not convinced. Alan

No harm in sending the picture to Lunt or Bresser Europe. They may say wait until it gets worse or just send a replacement anyway, as it will need replacement in the future. I'll have a go at aggresively cleaning the old filter when I get the replacement (there are several suggestions on CN) to see if the deposit can be removed. Alan

If you see the light in the reflection it looks more white but if you shine the light at an angle and view it such that the light source isn't directly visible in the reflection it then appears as green. I assumed that's what bilbo wanted, but with his image showing the light itself shown in the reflection, I think I've got it wrong and would have to say it's more white than green. Sorry bilbo. (S/N 0001005) Alan

I got a reply from Bresser, Germany that they have put a blue glass filter in the post today. The filter looks green if you shine a light off it at an angle but is pale blue when you remove it. The blotches around the edge indicate the blue glass filter needs replacing as it will get worse. In my post on Saturday I included a picture of the rear of the rear of the red output lens which also seemed to have a cloudy film on it. With the blue glass removed waiting for the replacement it's much more obvious. Danenn posted earlier on this thread of a similar problem so following his lead I removed the orange plate which has the diagonal mirror loosely fixed to it by some foam padding. I originally thought there was a prism inside but it's just a mirror. You can easily see and get to the rear of the output filter then and it was covered in a cloudy film. I gently wiped it in a cotton bud sprayed with Baader Wonder Fluid and puffed a rocket blower over it and the film has gone. Whoop! A clear golden surface appeared. The mirror itself looked ok with no film present, just a few specks of dust which the blower removed. I also thought before, the inside of the diagonal had a white powdery coating on the surface but it is just the metal showing through where the black spray coating hasn't covered it. It does look just like over-spray from the outside coating and isn't intended to be fully covered. Hopefully when the replacement blue glass filter arrives I will get a good improvement in the view. Alan

Ah! good, Peter. That would strongly imply there is a resistor on the board and it's of a similar value to the your 5k. Leaving off your external resistor and connecting IN+ to 12V that would put 2mA through the LED, less than the 5mA quoted on the board spec but will still enough to light the led sufficiently for the opto-isolater to work. (If it didn't they wouldn't have used that value) The lack of relay clicking is still a bit intriguing. Perhaps the two 5k resistors that were in series when you did your test and only allowing 1mA through the LED was not enough to trigger it. Connect the IN+ to +12V and ground the IN- for the final test. Any relay click then? If not check they haven't sneakily used quiet relays by measuring across the relay contact terminals with your multimeter on continuity check. With the relay off there should be a short circuit between COM and NC and an open circuit between COM and NO. When the relay is triggered, see if you then get a short circuit between COM and NO and an open circuit between COM and NC. Check the relay which corresponds to the IN+ and IN- terminals you've used to trigger it. I've actually just ordered one of the relay boards off ebay as they are very cheap and could be useful. I believe they all come from China so it may be up to 2 weeks before it arrives. If you're still having trouble then I should be able to help you out more easily. Alan

If the IN+ and IN- do connect across the LED of the opto-isolator like your previous diagram Hugh, then the resistor in series with the LED is not really a pull-up resistor, but a LED current limiting resistor. The board spec I listed above specifies trigger current of 5mA which would be the current through the LED. As the LED drops around 2V the series resistor needs to be (12-2V) / 5mA which is 2k ohms. Having a single resistor with the IN+ connections joined together the 5mA resistor current gets split between the LEDs if more than one relay needs to be turned on. Having three relays on, each LED only gets 1.6mA which may not be enough to switch its associated opto-isolater transistor reliably. It would be better to have a separate resistor for each IN+ to the +12V so that each LED gets 5mA whether 1, 2 or 3 relays need to be turned on. Measuring across the IN+ and IN- terminals with a multimeter on ohms may not be a reliable method to determine whether there is a series resistor as the multimeter may not supply enough voltage or current to turn on the LED and give an accurate lower value resistance reading. I would connect a resistor from one IN+ terminal to +12V, (ideally a 2k one but if you only have 5k resistors it should still work. Connecting two 5k resistors in parallel will give you 2.5k which would be fine). Then with your multimeter on volts, measure across the resistor and connect the IN- to ground. Hopefully you should hear the relay click. If the multimeter is reading about 10V then there is no on board resistor, and your external resistor is needed. If the multimeter reads around half that, between say 4V and 6V then there is an on board resistor of a similar value already there, and there should be no need for an external resistor. In this case as Hugh said the IN+ can be connected to +12V. Alan