Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_lunar_landings.thumb.jpg.b50378d0845690d8a03305a49923eb40.jpg

Lonestar70

Members
  • Content Count

    636
  • Joined

  • Last visited

Everything posted by Lonestar70

  1. From one RETIRED newbie to another (SEMI-RETIRED) welcome to SGL. You will find everyone here very friendly and extremely helpfull. Clear Skies. Sandy.
  2. Hi Everyone, I hope this is posted in the right place... apologies if not. I currently use my SW ED80 pro on my HEQ5 mount and have found that balancing the thing in DEC impossible (no problem in RA), especially when it has the focal reducer/field flattener and DSLR attached, without resorting to adding a home made weight to the front end of the dovetail bar. The use of a longer dovetail bar is not really practical, since it would interfere with the focuser (now motorised) and ,possibly, the camera... and the OTA is already as far forward in the tube rings as it can be. As I am just starting to look into guiding using an SPC900 LX modified camera in conjunction with the 9 x 50 finderscope (which will add more back end weight) and, whilst I appreciate a little camera heavy is desireable,... the current setup leaves a lot to be desired. I would appreciate any suggestions any of you may have as to how else this balance might be achieved? And how much 'Camera heavy' will PHD tolerate? Best regards, Sandy.
  3. I have just weighed my own SW 150PDS (not the same as 150P) and it is 4.9Kg including tube rings, dovetail bar and finderscope... but without eyepiece. The tube assembly is 70cm long x 80cm dia (not including focuser). This is well within the capabilities of the AZ4 mount. As far as I am aware... the head section of the AZ4 can be removed and fitted to the HEQ5 steel tripod. Hope this helps. Best regards. Sandy.
  4. Evening everyone, Many thanks for the warm welcome. Yes I do have a few things to keep me occupied when the dreaded clouds roll in (seems like everyday up here at the moment). Currently trying to get to grips with Guiding using my LX modified SPC900 on a 9 x 50 finder... thinking about making a small Crayford focuser for it... trying to focus with the threaded objective housing is proving to be a real pain. Ho hum!! It's all great fun. Best regards. Sandy
  5. Hi mindburner, OK then... from what you have tried and established It would certainly suggest that your regulator is a DUFF ONE. On the heat side of things: - I am not surprised that your transformer is getting very hot... it is only rated for 2.8Amps at the full 36v output. If you use the centre tap you will reduce this to 1.4Amps... yes it will probably supply the 4.3Amps you are drawing but transformer regulation will be all over the place... and it will get very hot... and will certainly give your regulator a lot of headache's trying to keep up... creating yet more heat. You need to replace it with a more suitable unit before you end up with a fire and possible injury to yourself... that is not what is required. Rapid electronics have a couple of suitable ones. 75VA 230v primary with 2 secondaries. part no. 88-3447 has 2 x 9v secondaries which can be joined in series to give you 18v. part no. 88-3449 has 2 x 15v secondaries which can be used in parallel giving 15v. Either will supply around 5Amps and not get hot and a very good price at the moment. http://www.rapidonline.com Do not try using the full secondary on your existing transformer... this will give you 36v out which is too high for your LF1038 regulator (max is 30v) and can still only provide 2.8Amps without overheating. Sorry to be the bearer of bad news. On a lighter note... thats a very nice image you have captured of M42. Best regards. Sandy.
  6. Hi again mindbender, No problem, pleased to be of some help. Ok then, even though you have a mica washer under the regulator these are prone to failure when changing things about... there should also be 2 plastic bushes to isolate the bolt passing through the device and heatsink. If you have a multimeter available then it is easy to check for a short... if you put the multimeter in Ohms mode and check between the TAB on the regulator and the heatsink/0v you should get a highish reading...1 kOhms or more... if you get a low or zero reading then check the bushes and mica washer for damage. One other check to make is to see if you have cracked the circuit board track between the output pin on the regulator and the nearest other component (probably the 300 Ohm resistor) It is easy to do this when you un-solder a connection to replace a component. You should get a zero reading when doing this test Hopefully it is just the change to a 100 Ohm resistor and change of pot that will get you up and running again. NOTE** make sure the circuit is powered down before making the above checks. Just out of interest... what is your maximum load current requirement? Best regards. Sandy.
  7. Hi everyone, from a very wet, and cloudy Argyll. I have been lurking for quite a while and thought it was time to join the club. My name is Sandy and I am a retired electronics and software design engineer. I have always had a love of astronomy and retirement now allows me to indulge in it a lot more than just a quick look around with binoculars. My main interest is in ASTROPHOTOGRAPHY and have purchased the necessary mount (HEQ5 pro) and a couple of scopes (SW 150PDS reflector and an ED80 pro refractor) along with various eyepieces, focal reducers atc. I control the mount using EQmod. I still enjoy the electronics side of life and have built my own ASCOM focuser (SGL TYPE) and power distribution board/box including Dew heater controls, flat panel control etc. I use a Nikon D90 DSLR and also an LX modified SPC900. Other interests are Model steam engines and boilers, Model Boats and wildlife Photograhy. I hope to be able to add something to the mix here on SGL. Best regards to all. Sandy
  8. Hi All, I am new here, having just joined, but have been lurking on the forum for some time. I have been following this thread with interest (as a retired electronics engineer) and I thought a couple of things may have been overlooked in the change over to the LF1083. Firstly: - have you made sure that the TAB of the new regulator is isolated properly from the heatsink?... especially if the heatsink is attached to the project case, which may be either at 0v and/or earth.... this would short out the output pin and prevent the regulator from turning on. (note... you may not get a big bang in such a case as the internal short circuit limiting would prevent the output from passing current. Secondly: - The LF1083 requires a more strict bias regime than the LM338 in that it must have at the very minimum 5mA of bias current (10mA would be best). It also requires a minimum load of 10mA. The 300 Ohm resistor in your existing circuit would only provide 4.16ma of bias current. If you change this resistor to 100 Ohms this would provide 13.75mA of bias current and also provide the minimum load current. The control pot (10K at present) is far to large to be used with a 100 Ohm bias resistor and would make setting the output voltage very touchy (sensitive)... A value of 1k Ohms - 2K Ohms would be more appropriate and would make setting easier. Hope this helps. Best regards. Sandy.
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.