Element14 / Newark
|Female D Sub Connector||79K4993||Plastic Hood For Db-9|
|D Sub Connector Housing||07H2397||DB9 Female Connector|
|RJ10 Plug||15R3068||RJ45 Plug (10-Pack)|
|FTDI based Serial to USB adapter||14N9613||FTDI Based RS232 -USB|
|10 feet Cat 3 cable||Source Locally||Source Locally|
|Soldering Station||Soldering Station||SFE Soldering Station|
|Solder||Kester Solder||Solder 60/40 1.0mm|
|Helping Hands||Helping Hands||Illuminated Helping Hands|
|Screw Drivers||Screw Driver Set||Electrical Screwdriver Set|
|Wire Strippers||Klein Wire Strippers||Wire Stripper Bundle 30-10 AWG|
|Heat Shrink Tubing||Heat Shrink Kit||Heat Shrink Assortment 160 Pcs|
DIY Meade 505 Cable
Most of our readers here will be surprised to learn that I am an avid amateur astronomer. I spend every chance I get under the stars taking in the amazing views that can be seen from my 10" Meade LXD-55 Schmidt Newtonian. With my background in photography, it should come as no surprise that I have shifted more into astrophotography than visual observing. My imaging sessions are usually conducted with two of my best friends at a private observatory owned by one of them . The observatory is nice but it is located about 35-40 minutes from me and thus I do not get out there as much as I would like to. So over the last couple of months I have been gearing up my scope for imaging. One of the first task I had to tackle was building a cable that would allow me to control my telescope from my PC, and that is what today's tutorial is all about.
There are several reasons one would want to control their telescope with a PC:
Over the course of building this tutorial many people have asked me "Why not just buy the cable? They are cheap enough on Amazon or EBay." and my reply has been the same every time. "Why not build it myself?" Sure it would be faster, and with a little patience, it may even be cheaper, but none of those give me the satisfaction of saying "I built that!" Plus DIYing things is the core of the Maker Spirit!
Above this post you will find a parts list as well as a tools list. These are new features that you will find on all of our future tutorials. They serve two purposes, to help you quickly locate the parts needed to complete the tutorial, and to hopefully generate a little income for us here at TMWB. Each time you click on a part or tool link and purchase that item, Amazon or Element14 will cut us a small percentage of the sale. By ordering through our links, you help keep TMWB running and that enables us to focus more on building projects and tutorials.
Building the cable is quite simple and only requires soldering 3 joints and placing 3 wires into a RJ10 plug and crimping the punch downs to secure the cable. The schematic below is what we will be following. I found this diagram online several months ago and do not remember where I found it. If it is yours, please contact me so I can add attribution. I have edited it to display the colors of the wires we will be using.
Basically we just need to cross the TX and RX lines between the DB9 connector and the RJ10 jack. The ground pins also get a connection between them. When orienting the RJ10 connector align the plug so that the closed end is facing you and the tab is on the bottom. The #1 pin will then be on the left and the #4 pin on the right.
So lets get started! The first thing we need to do is lay everything out so that it will be easier to find during the build. For this cable we will be using CAT3 telephone cable because we had a roll laying around. CAT 5, or CAT6 would work equally as well too. This CAT3 is solid core and not stranded. You can use stranded if you like.
When working with coiled wire I have found that a simple Velcro cable tie works wonders in keeping things nice and neat.
A pair of helping hands also goes a long way in helping to keep things safe and organized.
You will need to strip about 1" of the CAT3's jacket.
You need to be careful here as a razor will easily cut into the strands of wire below. A little tip I picked up from a networking friend once was to just lightly score the jacket with a razor then bend it at the score and the jacket will snap off.
With the jacket off, spread out the wires to make it easier to cut the ones we are not going to use away.
We will be using the Solid Green, Solid Blue and Solid Orange cables, the rest can be snipped off with wire strippers.
Select a piece of heat shrink that barely fits over the cables jacket and slide it a few inches down the cable. You will also notice that I have trimmed the wires a little. This is just personal preference and it is up to you if you want to do it or not.
Slide the wires into the RJ10 Plug as shown in the diagram. If you are looking at the plug with the tab facing you and the wires entering from the right, the wires should be placed as follows: Orange in the top, next space down is empty, next space down is green, and the blue is place in the last space. Refer to the schematic if you need to. When you are certain that the wires are in the correct place, use a pair of pliers or a crimp tool to push the metal contacts down.
Moving on to the other end of the cable, you need to strip the jacket and remove the unwanted wires just like we did before. This time however, you will need to strip about 1/4 of an inch of insulation from each wire as shown above.
Position the DB9 connector for soldering using the helping hands. Take note that most DB9 connectors are labeled on both sides. Pay attention to the pin numbers.
Some people like to place the wire in to the connector then apply solder, but I have found that it is much easier to fill the pin with solder first then reheat and push in the wire. This makes for a much better connection, and is easier to control in my opinion. This is also the time to slide on the heat shrink tubing. I place a piece onto the 3 wires as well as a piece down the jacket a little ways.
Now solder in the 3 wires in the following order: Green goes to pin 2. Blue goes to pin 3. and Orange goes to Pin 5.
Slide the smaller heat shrink up the wires and use a heat source to shrink it. Then do the same with the large piece of heat shrink. It may be wise to double up on this large piece of heat shrink depending on which housing you purchased. The only I picked up at Newark had a larger collar than my cable and I had to use electrical tape to fill the void as you will see in the following image.
Now you need to place the connector into the housing. This is pretty much self explanatory but I wanted to show you where I needed to add duct tape to make the collar fit. An extra piece of heat shrink would have fixed this.
Everything assembled nice and tight.
I forgot to show you how I heat shrinked the RJ10 connector. If you place the heat shrink on the outside you will have clearance issues when trying to plug it into your telescope. For maximum protection you need to quickly shrink the tip of the tubing and slide it inside the plug, then shrink the rest of the tubing.
All that is left is to screw on your FTDI based Serial to USB converter and plug it in to your scope and PC to test.
All in all this build took me about 15 minutes and I have less than $17 in parts. I can now place my telescope outside, set it up for imaging and then run the cables inside my house where I can stay warm while the hours long process of capturing hundreds of subs takes place. I will be writing a second part to this tutorial that explains how to install the ASCOM drivers, and other software needed to get everything working correctly.
If you would like to see more Astronomy based tutorials or projects featured here then please leave us a comment and let us know. In the mean time check out some of the awesome Reviews, and Tutorials we have here on the site. Thanks for reading and we hope you come back for more!