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Wireless Control of an Astro-Video Camera’s On-Screen Display (OSD) Options and Video


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Wireless Control of an Astro-Video Camera’s On-Screen Display (OSD) Options and Video

 

Recommended for someone with good soldering skills and a basic knowledge of electronics

 

Fred Wegener


 

Astrovideography has been around for a number of years now. The video cameras used cover a wide range of manufacturers and price points. Some are designed specifically for the astronomy community, while others are high resolution security cameras that have been adapted for use. There are already a number of articles online detailing the use of these cameras, so I won’t go into that. Most of the cameras have buttons on their back panels that are pressed to make adjustments using their OSD (On Screen Display), options. This, of course, requires the user to physically touch the device multiple times once it has been aligned to a desired target, so is not ideal! If you know what you’re doing, you can very carefully add a multi-wire cable to the camera, soldering connections to the internal switching.

 

After running said cable to a homemade switch box, you can then adjust the settings without touching the camera; however, you now have a 12 volt cable to the mount, another one to the camera, a video cable from the camera to the monitor and another cable running to the homemade control box. I wanted to simplify this issue!

 

2015 (or so)…..

 

Above is a picture of the UTC (Up The Coax) hand controller that was supplied with my Revolution Imager. It plugs directly into the video output jack on the camera on one side of the connector while the other side connects to your monitor. This eliminates the need to build a custom control installation, as described above, but still has the requisite controller cable. My original plan was to build a smaller version that lacked the control pad, using wirelessly controlled relays in its place. It would run directly off the 12vdc from the scope mount supply. However, I could find almost no technical information online as to exactly how this thing works, or a source for the integrated circuit required, so had to come up with a “Plan B,” which was to modify the existing device to suit my needs. Perhaps not the most elegant approach, but hey, it’s relatively simple and it works!

 

To begin, I acquired a 6 channel, wireless relay control setup from an Ebay dealer. These are designed for many different possible applications, are very small and have considerable range of operation (not really an issue with camera control on a telescope!). Conveniently, the receiver/relay board is designed to run on 12 volts DC. This item is detailed in the following images.


 



 

Essentially, the objective here is to wire the contacts from the UTC controller’s shuttle pad to the relays on the relay control board so that the relays then perform the same function as the switches on the controller’s shuttle pad. In order to do this, we must open the case of the UTC controller and remove the top of the relay board. The relay board is straight forward; it just snaps in place. Not so easy with the UTC controller; it appears to be both snapped and glued together. To open its case, remove the battery tray, then carefully start prying around the periphery of the case. I used a knife for this task, but I recommend using whatever you’re comfortable with and feel safe using! I assume no responsibility for damages done! There were a couple of spots – one on each side – where I could feel the blade sink into the inside of the case, so those became my leverage points. From there, I just continued to work it until it popped apart. Once it is apart, remove the circuit card and lay it so the single integrated circuit is facing up.

 


Wiring to the UTC Controller

 

First, review the explanation to the right of the drawing. Here you can see the colors I chose for my wiring. I actually did not solder the wires (24 gauge), to the feedthrough points, but rather scraped about ¼” of coating off the circuit trace extending from each point and soldered there. This will give you more surface area to solder to, hence a stronger connection.

 

The wires are shown exiting on one side. After lining them up side-by-side, I secured them in place with tape and applied epoxy glue (indicated by the pale, blue oval shape), to hold them in place and prevent strain on the solder joints and circuit traces. I then used a rotary tool with a conical shaped abrasion bit to route out the plastic casing so the wiring did not interfere with normal closure of the two-part case. Once the glue was set and the casing modified, I snapped the assembly back together and reinserted the battery.

 

This is the way things were done for “proof of principle” testing (see following image).

 

 

Having the overall control setup broken into two parts, however, is not very neat and tidy, so I decided to cut the UTC controller board in the vicinity of the red, dotted line, then add a small circuit that converts 12vdc down to 3.5vdc, which is what the controller requires. At that point, the mount itself, the imager, the relay control board and the UTC controller will all require the same voltage. I originally planned to mount the relay control board and the UTC controller in a plastic project box and feed them with the 12 volts currently being supplied to the mount, but have since decided to include a 12v, 6000mah lithium ion battery pack in that box. With the box then mounted to the side of the telescope, I will be able to power ALL imaging and control components without having wires dangling between the scope and the mount.

 


Let’s Make It Run on 12 Volts….

 

 

Above is the schematic for the 12v to 3.5v converter. As supplied, the hand controller operates on a 3 volt lithium button cell, but manufacturer’s specs on the integrated circuit show it is rated for 2.5 to 6 volt operation, so I chose 3.5. That will keep the voltage within operating range for quite some time as the battery starts to drop. I used a 2N2222, to control the voltage, but there are many small-signal NPN transistors that may be used here as the current requirement is very low.

 

 

Above you see my trimmed-down version of the UTC controller card. At point A, you can see the relation between the notch in the card and my cut line. Point B indicates a convenient place to tie-in the +3.5 volts. It is a position marked for resistor R14, but there is no resistor there. The solder spot and trace closest to the edge of the card has + voltage fed directly to it, so this is where I wired in. The green wire (ground), is soldered across a couple of the feed- through contacts; they’re ALL ground. The converter is epoxied to the UTC card as shown.

 


Now, on to the subject of getting rid of the REST of the cables!

 

 

 

This block diagram illustrates (in concept), how, once the 6000mah battery is added to the picture, you can rid yourself of the power cabling between the mount, the imager and the wireless control circuitry. Looking at the block diagram of the camera and you will notice a “video transmitter” block. These little guys, shown on the left hand side of the image, are made to provide instant video between a boat trailer, camper, etc.,and the inside of the towing vehicle. One transmits while the other receives. They are tiny, operate on 12 volts and broadcast and receive at 2.4ghz. A few years back, I adapted a Samsung SUB2000 camera to astro use and designed and built a complete wireless operating system for it. This was before UTC control, so my system used DTMF encoding and decoding broadcast over modified FRS radios. UTC is SO much easier! Anyway, I used these little guys for my video and they work quite well. The really great part is that you can buy the pair of them for less than $15!

 

I just used sticky-backed Velcro to hold the transmitter on the top of the Samsung and the receiver to the backside of the video monitor setup.


 


Concept to Reality

 

 

I chose to incorporate the pieces into a Bud CU-3283 box, as shown above. You could mount them in any non-metallic enclosure you like that would fit the parts. In fact, I almost went with PVC pipe, thinking it might match the contours of the telescope better. The battery mix and make-up is also a matter of choice as long as the current and voltage requirements are met. The Talent Cell battery pack I chose has charge status LEDs on the top and I wanted to be able to remove it easily for use elsewhere, so a mounting setup was configured to allow easy installation and removal as well as visibility to the charge status monitors. This allows charging in place, if desired. The hole for the battery was cut using a rotary tool with an extension wand, then filing and sanding afterwards. The battery pack is designed to feed power from a coaxial power jack on the forward end of the box, so a panel- mount, coaxial receptacle was installed directly above it on the enclosure box, as indicated by the arrows. In use, a short, coaxial jumper connects the battery to the rest of the electronics in the box.

 

Power distribution wiring is also shown above. For the sake of uniformity, all connectors are 5.5mm x 2.1mm, coaxial, panel-mount. Resistors are 10K, ¼ watt, but may be adjusted to suit, depending on the LEDs chosen. I happened to have a number of unmarked, sub-mini LEDs leftover from a project from many years ago, but just about any small, red LED will work…your choice. Switches are miniature SPDT (on-on). SPST would have been fine, too. All parts, including the battery pack, should be available on Amazon.

 


 

A “sub-floor” was installed on top of the battery retainer framework. This allows installation of the electronic components. The relay board is secured with screws to the plastic base it came with and the base itself is glued to the sub-floor. The two small, wooden blocks are used to secure the UTC board, with the 12 to 3.5 volt converter extending downward into the cutout at the right end of the box. Here you can see the holes that have been drilled for the switches and panel-mount coaxial connectors. One of each is mounted in place to illustrate. A third hole for the LED was drilled just below and centered between the coax connector and the switch.

 

 

To the right is the completed assembly. Note the zip tie on the UTC line. This should be snugged, NOT tightened, then glued to the cable. Tightening may damage the coax. The zip tie is placed behind the indicated notch when the box lid is installed and serves as strain relief for the cable. The area circled in blue is a two-pole tie point screwed into the sub-floor and battery framework beneath. It serves as a convenient way to tie power wiring for the two circuit assemblies together.


 

 

Wireless Monitor

 

In a couple of images you can see a portable monitor. In my tests, I had the camera video jacked into the back of it simply because my video transmitter was still mounted to the SUB2000. The monitor circuitry already includes the wireless receiver mentioned earlier. My diagram below suggests 12 volt AA batteries. What I actually used was 10 AA NiMH batteries, so I could recharge them. The way the charge jack is wired makes the outer portion (+) while the inner contact is (-). Not really an issue, but kind of backwards, so you have to be careful that your charger is wired accordingly! The monitor itself is a 7”, NTSC compatible monitor for portable use. Found it on Ebay.

 

 

 

By the way, with the wireless receiver “off,” video can be cabled directly into the monitor. With it “on,” you can attach a video grabber for use with a computer.

 


NOTE: The wireless video receiver can be used with any NTSC compatible monitor. For that reason, I’m not going to go into great depth about the monitor. This portable setup was designed for use with my Samsung SUB2000 project a few years back, but will work with this one as well.

 

In Conclusion…

 

This concludes my rambling project. If you build just the wireless UTC control portion, you have just reduced your dangling cable load by a factor of 1. If you opt to build it all, you will have 0 dangling cables associated with your video imaging system. To my way of thinking, the less I have to snag and get tripped on in the dark, the better!

 

 

Clear skies!

Fred

 




1 Comments

It would be great if this set up could be made commercially available at a reasonable rate for those of us who do not have the electronic skills of the author. 



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