Moonlite Filterslide and GLP Dummy Battery

Some of you guys may remember, I really wanted to implement some way to be able to move a filterslide without lifting the scope shroud or reaching in from the front of the 16" Lightbridge. This would have been a bit of a stretch because I have added a permanent Kydex Lightshield to the UTA that extends its lenght 100%

I sat down and had a good brainstorming session. I arrayed spare parts from all sorts of things on the table in front of me and put my thinking cap on. What I came up with was using the drivewheel, axle and gear cog of a warranty replaced azimuth motor from my JMI TNT tracking system, as a manual knob for sliding the filterslide. The gear cog with the teeth filed off and with some rubber from a brush handle glued on as a tyre was the perfect dimensions to engage with the edge of the filterslide with the axle going through the unused bolt holes for non moonlite focusers. Of course I had to Dremel out a slot for the filterslide drivewheel. I also Dremeled the top edge of the filterslide to give the drivewheel the necessary traction.

It worked!! The knob looks like its part of the focuser and now I could change filters from the focuser without reaching in behind the shroud or reaching around the front. However I needed a way to know when a filter was in position without either having to pull out EPs to look down the drawtube or looking down the front of the scope. Both would render the whole filter slide kinda moot. ie. A primary advantage of the filterslide is not having to be removing and reinserting EP's to change filters and to very quickly change from one filter to another to do direct comparisons between one filter view and another. And of course the operation of the filterslide from the focuser without having to reach down the front of the scope is rendered kinda moot if I have to walk around to the front and peer in anyway to check on filter positions.

While I had initially hoped to trigger a different LED light for each filter position I quickly realised it would not be possible with the parts I had to hand and I did not feel like paying several dollars for shipping parts that cost a quarter each! It turns out that the DVD-Rom drive did not die in vain even though I didn't use the motor I stripped from it after all. I found a little Kill Switch inside the drive that was used to shut off the motor when it reached the end of its travel. I mounted this kill switch to the filterslide frame and glued little 'ramps' of plastic to the filterslide at the appropriate positions. When a filter is in the correct position the plastic ramps depress the spring loaded kill switch thus turning off a red LED. I had started to brainstorm how I might reverse this and have the light come on when a filter was in position until I realised that it was actually better the way it was. Who wants a red LED lit up beside their eyeball at the EP. Much better to have the LED on to indicate when a filter is out of position but to switch off when the filter is in position and your are ready to look through the EP.

I mounted the LED in a black metal housing from the unused TNT gearbox which will be affixed beside the focuser. Necessity is the mother of invention Azimuth dirve wheels for manual knobs, brush handle rubber hand grip for a tyre, kill switch from old DVD rom drive and gearbox housing from motor.

Heres a link to a little video of the filterslide in operation. In the vid I turned the knob with my hand in a position so as not to block the view of the camera. In actual real world use with my hand positioned correctly when turning the knob means I can move from one filter to the next with one twist of the fingers. You'll also note that the LED indicator is very bright. I'll be dimming that down significantly. You may also notice a silver dipswitch below the LED indicator. Thats the on/off switch for my scope mounted Green Laser Pointer. As for the noise. I am hoping a small bit of grease will quieten that down Theres also some close-up pictures of the focuser/filterslide. The camera flash shows up every spec of dust and tiny blemish.

Heres the Link to the Vid and photos on my Flikr page.

Filterslide - a set on Flickr

I also made the Dummy Battery for my GLP. Turns out that the Female RCA socket from the Filterslides Dew heater that I didn't need fit the cap of the GLP perfectly.

Heres some pics of my GLP Mod that is scope mounted in a Scopestuff GLP mount. A .925" Dew heater strip underneath keeps it warm and thus the beam at full brightness.(Thank you Jeff Young(JeyJey) for that idea) It eats batteries (2xAAA) and thus I wanted to power it from the 3v power output of my Dewbuster Dew Controller. Thus I needed to fabricate a dummy battery. Its just a small wooden dowel with a wire through the middle running to a wide head screw on one end and wired to a phono/rca female socket affixed to the lasers cap on the other end. I wrapped the dowel in heatshrink for a neat look and snug fit inside the laser. I actually have a spare unmodded cap from an older broken GLP and thus I can remove the dummy battery and Phono cap and replace with 2 AAA and the unmodded cap to use the GLP handheld too should I want to.