Zengineering is pleased to announce our latest products. The Triple Function ST4 Compatible Relay Box, and the Dual Function ST4 Compatible Relay Box. These amazing, "groundbreaking" devices will allow owners of telescope mounts with a standard 6-Pin CCD guiding port, to autoguide using the free GuideDog software and a PC. What sets these relay boxes apart from "all the rest" are the amazing extra functions "built in", and all controlled by a single parallel port. Functions like SC Modified Webcam Control, Canon Digital Rebel/300D Shutter Control w/Indicator LED, Correctly Oriented Guiding Impulse LEDs, and USB +5V Relay Box Power for user convenience.

We offer two models to accommodate those users that don't require the DSLR control circuitry. The only difference between the two Relay Boxes is that the Dual Function ST4 Compatible Relay Box doesn't have the DSLR control circuitry or cable, The Triple Function ST4 Compatible Relay Box does have it.

"Hi, I just wanted to let you know that I tried your relay box and the hand controller you modified for me yesterday, and you were right. It really did work right out of the box! Let me start by saying that I was really impressed by the design of the relay box. All cables were just the right length so that the box could be kept close to the PC to avoid falling over the clumpsy parallel-port cable. Your handcontrol modification was really discrete and it was nice of you to add the string so I don't have to put it on the ground when not holding it. I plotted the guide-error file using MATLAB and after a little 'fibbling around' with the parameters in guide-dog the accuracy was really impressive (althoug the EQ-6 is known to have significant periodic errors). Hynrik L., Sweden"

In reference to the above customer comment, Zengineering modified Hynrik's EQ6 hand controller by adding an ST4 compatible port to allow autoguiding. Hynrik simply send us his EQ6 hand controller, we then performed the modification and shipped it back to him along with one of our Dual Function Relay Boxes. Shipping his tiny hand controller to us insured no damage to his expensive EQ6 mount and kept shipping costs to a minimum. We can perform a similar modification for you at a very reasonable price. Contact us for details.

Above you can see the Modification we performed on Hynrik's EQ6 hand controller to allow autoguiding in conjunction with our Relay Boxes.

Many designs were considered prior to creating our Multifunction ST4 Compatible Relay Boxes. Including the recent inexpensive optocoupler based pass-through products. However, upon researching the optocoupler itself, it was obvious there were a few trade-offs that come with its use.

Firstly, I am not trying to flame or insult anyone else’s designs. With that said, I will share with you what helped me decide on our circuit design rather than an optocoupler design.

From what I know of optocouplers (also called phototransistors):

a) They are notorious for slow switching, as there is no path for the stored charge. This could come into play when you consider the fast response times required to autoguide a large variety of mounts. The average optocoupler has a response time around 80µs (microseconds). The circuit we employ responds to guiding impulses in less than 20 nanoseconds, simply much faster. An optocoupler might just get the job done, but I prefer our faster, more dependable, USB powered circuit be used on my $2000 Servocat drive system.

b) The average parallel port is susceptible to wide fluctuations in voltage (voltage in signal pins can randomly drop too much) in some system configurations. Also, the current output is naturally very low per parallel port pin. Although, the optocoupler is just within spec on this issue, it is still not ideal. Our relay boxes are powered by a reliable and stable power supply, regardless of a parallel port’s condition. Again, I want the best for my equipment. And the most compatibility. This is my opinion.

c) Most importantly, optocouplers have been known to have problems with excessive data RF frequency. The optocoupler could cause errors or dropouts in the data stream. In the case of autoguiding, the extremely long cables involved make this a primary issue. I sit in my trailer about 30’ away from my scope when imaging. I require several 35’ cables to get it done. RF frequency errors can come into play with an optocoupler even when using cables of very short length (1’ or less). I preferred to eliminate the RF issue altogether with our circuit solution. An optocoupler alone might work for a budget solution, but I opt for a more reliable circuit, one that is ready to work on the largest variety of parallel ports.

Factors other than optocoupler issues led me to my design choice. Mainly, I prefer properly aligned LED visual indicators when autoguiding, not only for the valuable real time visual reference, but for insuring the proper function of a finicky parallel port prior to actually plugging everything into my mount. The exclusive USB power usage of our relay boxes makes this ability not only possible, but something you'll get used to very fast, and won't want to be without.

Add it all up…and think of how much you have invested in your telescope, mount, and accessories, then make your decision.

!!Happy Autoguiding!!

Triple Function ST4 Compatible Relay Box	Dual Function ST4 Compatible Relay Box	Other single function relay boxes
*ST4 Compatible Autoguiding	*ST4 Compatible Autoguiding	*ST4 Compatible Autoguiding
Full SC Modified Webcam Control	Full SC Modified Webcam Control	Little or none at all...
Correctly Oriented Guiding Impulse LEDs	Correctly Oriented Guiding Impulse LEDs	Either in a straight line, or none at all?
USB +5V Relay Box Power	USB +5V Relay Box Power	AC power transformer or DC power needed
Canon Digital Rebel/300D Shutter Control w/Indicator LED	-----------------none----------------	-----------------none----------------
15' AutoGuiding Cable & 15' DSLR Cable Included!!	15' AutoGuiding Cable Included!!	None at all!!

*ST4 Compatible Autoguiding - Works with most telescope mounts that have a "standard 6-Pin CCD guiding port", like the LX50, LX90, LX200, Losmondy G11, Celestron Advanced Series, and many more, including the cutting edge ServoCat system. (Guaranteed to work with the new ServoCat system!) An RJ12 to RJ12 6-Pin cable is required (included) to go from the relay box to your mount's autoguiding port. We offer these cables in many other lengths as well (see our Cables for Relay Boxes & DSLRs page for more info).

SC Modified Webcam Control - It's now possible to use a low cost webcam (mounted to a small guidescope piggybacked to your main imaging scope) as your autoguiding camera. Almost any digital camera/webcam will work, however our relay boxes are designed to also control long exposure modified (SC) webcams (like the SAC line of webcams). By triggering long exposures, this allows the user many more guide stars to choose from. We have also provided the ability to control the Amp off & Advanced SC mods of many webcams using GuideDog via the same parallel port.

Correctly Oriented Guiding Impulse LEDs - Other "single function" relay boxes have their impulse guide LED indicators in a straight line. Our multifunction relay boxes have the impulse guide indicators correctly oriented according to the actual cardinal points. It's simply more natural. This makes it a simple process to visually interpret real time guide signals. Be sure to correctly align your guiding camera so North is Up, South is Down, East is Right, And West is Left according to the GuideDog preview window.

The video above shows the triple function relay box in action. Get the Divx codec to view videos on this site.

USB +5V Relay Box Power Cable- Some mounts don't provide power on the guiding port for a relay box. With this in mind we have manufactured our relay boxes to take the required +5v from a PC's readily available "powered" USB ports. Unlike other relay boxes, this makes our multifunction relay boxes ready to go out of the box, without the need for an AC power transformer or DC power source. Any available powered USB port on your PC (Or powered USB hub) will work. (No data is sent over the USB cable, only +5v.) Our relay boxes WILL also work on mounts with powered autoguide ports. Their onboard power is simply not used.

Canon Digital Rebel/300D Shutter Control w/Indicator LED - This feature allows owners of the popular Canon Digital Rebel/300D DSLR camera to control the shutter release for long exposures beyond 30 seconds. This feature works in conjunction with the freely available DSLRControl software. A LED indicator on the relay box informs the user when a DSLR exposure is being triggered. Our relay boxes include a 3' cable to female 2.5mm plug onboard, and also come with a 15 foot (2.5mm Male to 2.5mm Male) cable to go from the relay box to your DSLR. Longer lengths of this cable are available as an option (see our Cables for Relay Boxes & DSLRs page for more info). DSLR shutter release control is NOT included in our Dual Function ST4 Compatible Relay Box.

Cables are included with our relay boxes - Unlike the other guys, we don't even sell those tiny 6' cables that can't even reach around your scope. We believe a reasonable cable length of at least 12' is needed to have a laptop near a telescope. More importantly, we INCLUDE (with every relay box purchase) a 15' autoguiding cable to go to your telescope's mount. Visit our Cables for Relay Boxes & DSLRs page if you require an even longer cable. Our Triple Function Relay Box also comes with a 15' DSLR shutter release cable, so you're ready to go out of the box.

Hardware Used	PC Ports Used	Cables Used
Triple Function Relay Box	1 PC Parallel Port	35' 2.5mm to 2.5mm DSLR shutter release cable
ServoCat Drive System	USB port for DSLR Camera	35' RJ12 to RJ12 6-pin cable (relay box to mount)
Canon Digital Rebel/300D DSLR Camera	USB port for Webcam	35' Webcam SC function trigger cable 4-pin RJ11 to RJ11
Sac7a SC Modified Webcam	USB port for Relay Box	4 - 10' USB Extension Cables (A-Male to A-Female)
Obsession 20" #730 Galaxy Telescope	USB port for Mouse, Wi-fi adapter, etc...	A 4-port powered USB hub is a wise purchase!
Apogee ST80 400mm Guidescope

Below is an excerpt from our Quick Start Guide, included with every Multifunction Relay Box:

"The key to successful autoguiding is to align your guiding camera (in this case a webcam) as precisely as possible so that North is Up, South is Down, East is Right, And West is Left according to the GuideDog preview window. This view will also match the orientation of our multifunction relay boxes. Of equal importance is tweaking your mount to track as accurately as possible. In the case of the ServoCat, upgrading to the latest firmware revision, making sure both axis are working correctly (not skipping encoder counts), balancing your telescope, and running the autocal procedure, should be considered prerequisites to getting the best accuracy. Be sure to also put the ServoCat into the slower "speed 2" mode (a switch on the front of ServoCat brain enclosure), as well as putting the handpad to the "guide" speed, prior to autoguiding. Finally, tweaking your tracking rate numbers and your backlash numbers within the GuideDog software to achieve good "round stars". This final step will vary significantly depending on the mount used."

Zengineering's Triple Function ST4 Compatible Relay Box - We include a FREE 15' 6-pin autoguider cable to go from the relay box to your mount, as well as a 15' DSLR 2.5mm male to 2.5mm male extension cable to go from the relay box to your Digital Rebel camera. Other cable lengths available on our Cables for Relay Boxes & DSLRs page. Each order will include a Quick Start Guide to get the buyer started.

Triple Function ST4 Compatible Relay Box = $150.00 US + $10 S+H (conus) International shipping add $10.00.

Zengineering's Dual Function ST4 Compatible Relay Box - We include a FREE 15' 6-pin autoguider cable to go from the relay box to your mount. Other cable lengths available on our Cables for Relay Boxes & DSLRs page. Each order will include a Quick Start Guide to get the buyer started.

Dual Function ST4 Compatible Relay Box = $125.00 US + $10 S+H (conus) International shipping add $10.00.

30 day money back guarantee, we'll refund the purchase price if not satisfied. Shipping and handling charges are NOT refundable.

The products Obsession, SAC, Canon, Apogee, ServoCat, DSLRFocus, GuideDog, and DSLRControl are the sole property of their respective owners.