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About symmetal

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    North Cornwall
  1. Battery box

    Ah! that makes sense Ray. As you say it's just personal choice. Happy to help Wookie.
  2. Battery box

    Personally, I would not have a switch in the voltmeter, as the current it draws (around 20mA) is not significant compared to the rest of your equipment and it's a useful 'On' indicator as well as battery voltage. If you want to try and protect the voltmeter with a fuse, use the lowest rating fuse you can. (I think 1A is the smallest blade fuse you can get). The USB module has a maximum load of 2.1A so I would put a 3A fuse in that circuit. It probably current limits at 2.1A but if not you don't want to risk it going short circuit through overload and delivering 12V to your 5V devices. Just my thoughts. Alan
  3. What Fuses

    Happy to help you out John. Hope the 25A cable will fit into your cigar connectors. If you wanted to run out two cables from your Nevada, you might as well use the front and rear connections on the 30A unit as it has more than enough capacity for everything. If you did use the 8A unit alongside the 30A one, connect the two -ve terminals together at the power supplies to have a common 'ground' reference. Your distribution box is fine, and there's no need to have a more expensive one. Alan
  4. What Fuses

    Hi John, The 40' cable you're using at the moment, 1 mm2 made up of 32/0.2mm strands has a resistance of 19.1 ohms / kilometre which is 0.019R/m. Your 40' run is 12m which has a resistance of 0.23R per core. Total resistance is therefore 0.46R. Drawing 4A, a typical figure for what you've got connected to your distribution box, the voltage drop on the cable is 1.84V so you just have just 12.0V for your equipment. If you draw say 6A total when you're slewing with everything else still powered the voltage drop is 2.76V leaving you with 11.0V for your equipment. This is below the recommended voltage and could cause problems accounting for the weird noises from your mount. The 2.0mm2 cable you mentioned has a resistance of 8.8R/km so at 6A current total drop is 1.27V. This leaves you with 12.53V across your equipment which is fine. The cigar connectors will also drop some voltage as they have a small contact area on the tip and the inbuilt fuse and connectors will also add a bit more resistance. I would try and not use these connectors. The 5A you currently have in the cigar plug connected to the 30A terminals definitely needs increasing to its maximum of 10A to save it blowing like it currently is. The option of having another connection to the cigar socket on the front of the Nevada powering some of your equipment (Dew heaters etc) is certainly an option which would reduce the voltage drop on your main cable but complicates running out your cables. You said you're using cigar connectors to have the option of using it in the field, but you wouldn't be using your 40' cable in the field would you? If you must use cigar connectors use the highest quality ones you can get. Instead of putting a cigar plug and socket connected right at the rear connectors on your Nevada, using the 25A cable you mentioned above, have a shorter cable to your distribution box ending in a cigar plug, fused at 10A, (say 10' long for use in the field) and a 30' long 25A cable connected to the rear terminals of the Nevada ending in a cigar socket. Put a 10A in-line fuse at the +ve wire at the Nevada rear as that's the rating of the cigar socket at the other end. You can get in-line fuse holders for blade fuses like the ones you're using. Using this method only one cable is needed to be run out from the Nevada at home, and in the field connect the 10' cable from your distribution box to your field power supply. Much shorter cable so voltage drop is not an issue. If you prefer, I can do a drawing of the above but see how you go. Alan
  5. Glad to hear you've managed to get it working after all your perseverance. It looks like your FF spacing is much more critical than mine. Alan
  6. What Fuses

    Hi John. From your last post it looks like the only cigarette plug used is the one plugged into your Nevada PSU. In which case the current for the whole of your rig is passing through the cigarette plug 5A fuse so it is quite likely to blow when your mount starts slewing. The dew heaters, camera and mount tracking along with the rest are probably taking around 4A and the extra 2 to 3A when your mount slews is exceeding its 5A capacity. The total current drawn is the sum of the individual currents. The quickest way around this is to increase the fuse in the cigarette plug to 10A. Looking at your picture of the Nevada PSU there is no sign of where you can use its 30A, so I assume there are 30A terminal connections on the rear. You could connect your fused distribution box to these terminals and bypass the cigarette connector which should give you a more reliable connection. If you don't use cable rated at 30A for the lead from your PSU you would need to put an inline fuse of around 10A, or whatever the rating of the cable used is, in the positive lead from the 30A terminals. Using cable rated at 30A would give the benefit of less voltage drop at your distribution box. The fuse used at the PSU end, whether using the cigarette plug or the rear terminals is only there to protect the cable going to your distribution box and not the equipment attached to it. The fuses in your distribution box protect your equipment. It looks like you have used 2 core mains cable as your current cable from the PSU. If this is 13A rated then a 10A fuse is fine at the PSU end. Alan
  7. Glad to help. The question isn't stupid, but having the term backfocus to mean how far the sensor is mounted from the front of the camera is. Alan
  8. The term backfocus is very misleading and means different things to different people. The 55mm 'backfocus' of your CC is the distance required between the CC back plate and the image sensor. A Canon DSLR has a 'backfocus' distance of 44.1mm between the sensor and the front of the lens flange. The T adapter has a depth of nominally 11mm. The 44.1 + 11 is about 55, the distance of your CC 'backfocus'. Hurrah! Your 17.5mm 'backfocus' of the ZWO is the distance between the sensor and the front plate of the camera. This means you would need a T extension of 55 - 17.5 = 37.5mm to achieve the CC 'backfocus' distance. The small chip size of the ZWO compared to your DSLR means that the CC probably isn't needed as only an area equivalent to a centre cut-out of your DSLR is being used so the coma error will be much reduced. Alan
  9. What Fuses

    Is the cigarette plug connected between your fuse box and the mount? It may be the cigarette plug fuse is a quick blow type while the blade fuses are time delay or slow blow fuses and can tolerate high currents for a short period. Did you use the same cigarette plug cable when you used your tracer battery? The tracer may have been slightly lower voltage than the Nevada or thinner cable and it just coped. Anything with motors should use slow blow fuses. With your fused distribution box there is no need for additional fuses in the leads to the mount. Alan
  10. As Ray says you need to add 1/3 the thickness of your filters to the flattener/ccd distance stated. I should have read your post more carefully. For a lengthy discussion on the subject read this thread. Do Filters Add To Back Focus Alan
  11. Hi Ian, I wouldn't have thought 0.5mm spacing error would have a great effect. On mine I did test runs from +/- 2mm in 0.5mm steps from the specified distance to check the optimum spacing and at 2mm out the image was visually still usable, just slightly elongated stars at the corners. CCD Inspector also indicated defocused stars at the centre though. I have the William Optics Flattener-IV which allows you to move the lens elements inside the tube so it's easy to adjust. Did you get my pm to you about CCD Inspector? Alan
  12. It's been recommended to do exposures for CCD Inspector pointing at the zenith to eliminate slop in your imaging train causing tilt though when I tried it there, there were insufficient stars for a usable result. I found pointing at an area of the Milky Way with no large bright nebulae or prominent galaxy clusters in view gave the best result. Also a high elevation is preferred, greater than 60 degrees or so to minimize seeing errors. Repeating after a meridian flip gives an indication as to whether there is slop in your imaging train. As RayD says a number of images of each view are required to get a reliable result (individual images, not stacked). Four or five will give a good indication of your problems, ten or more for fine tuning but I don't think you're at the fine tuning stage at the moment. Alan
  13. electronic componments

    I use cpc.farnell for most items and their sister company farnell element 14 for more specialized components along with RS. Alan
  14. Sorry to hear you're still having problems Ian. From your latest description it would appear to be related to field curvature as sloz says and maybe combined with image tilt as well As SGPro goes through its autofocus steps different areas of your image come into focus so the HFR readings are all over the place. I used CCD Inspector to sort out a slight tilt error in my setup and get best flattener spacing. You can use it free for a trial period. I found it so useful I bought the registered version although it's not cheap. The 3D display of the sensor 'flatness' I find the most imformative. If you want to post or pm me a sample image, near the best focus you can manage, preferably fits, though a high quality jpg would work I can give you a display of your image flatness which might help. Alan
  15. EQMOD cable

    Windows 10 has FTDI drivers built in so you don't need to install other drivers. Sometimes plugging it into a different USB port will kickstart Windows into recognizing it. With it plugged in, check in Windows 'Device Manager' to see if a device has a yellow exclamation mark against it (probably in the COM ports section). If so right click it and select 'Uninstall device'. Then unplug and re-plug your EQMOD adapter and see if windows now recognizes it. Alan