3-Pin Servo Connectors

[Caretaker.CCI]

I have a question about connectors. I really like the FC-4 and the RC-4 for controlling 120VAC but even with the clean connections that the PCB provides you're still dealing with potentially deadly voltages. Face it, you know and I know that on Halloween night, when things are hectic and you discover that something is not working right at the last minute, we've all put our hands in places that were potentially, "a bad idea" (even if you are the one that built the thing). It's even worse if one of your crew (helpers) puts their hand in the wrong place. At least you know the risks!

I have been putting all 120VAC components in enclosed boxes lately including fuses, indicator lights (so that I know something is on) and documentation. That way I know that all the electrical components that have a "bite" to them are inside and I'm outside.

Now here's the question: as you can see from the picture, I've been using DB-9 connectors as the interface between the Prop2 and the PCB mounted safely inside the box (an FC-4 in this case). This connector was used because I happen to have a bunch but it's not the easiest choice to go with. I'm about out of cables that have a DB-9 connector on them and installing the connector in the box is a labor-intensive job (lots of dremmeling = no fun!). Is there a convenient connector that would allow me the use of the standard servo connectors that are the usual method of connecting a Prop1 (or 2) to the outside world? You can't have 3-pins sticking out into thin air because I know they will get bent or broken off. Square connectors are OK but still a pain to install (I seem to have misplaced my square drill bits). I have an idea of what I think would be perfect but there is probably something out there that already exists and I just haven't found it.

Sorry this got a little long winded... the short of it is... I need a source for connectors for the hobby-servos that you use to connect different peripherals that would install easily in a project box. Anybody know of such an animal?

Thanks

Greg

[JonnyMac]

You could use a standard stereo jack as it has three conductors.  We're working on a 5-foot extender cable (our vendor is sending a sample) that you could easily hack by adding a stereo plug on one end.  The down-side of a stereo jack is that it doesn't have locking screws like a DB-9 does.

[Caretaker.CCI]

Is your vendor open to suggestions for new products? I have an idea (in my head) that I think would be real popular. It's simple in design, would be easy to install and probably cheap to make (just guessing on this one). I'll try drawing it to see if it looks like what I envision. In the mean time, I was hoping someone had run across an idea that already exists.

A stereo connector would be OK but I don't know of a source for "cheap" connectors. Besides, I would like to be able to use the servo connector cables as they are without modifying them.

Greg

[JonnyMac]

Well, if you want to buy 1000 things at a time from them -- they're open to anything....

[menehune]

Another option could be to use a XLR type plug and bulkhead mount receptacle. 
Both connectors are locking.  They are around $3 for the female connector and $6 for the male bulkhead connector.

Circular main connector hole with two or four smaller mounting screw holes.  Last time I used one, I think I used a 3/4" main hole and a 1/8" bit for the mounting screws.

[avgjoefriday]

Hey Greg,

Thanks for posting this.  I have actually been working on something similar to the device you posted the pic of.  In my case, I am trying to mount up 4 of the FC-4s for next christmas.

Three quick questions for you....
1 - Could you post up a pic of the insides?
2 - How did you get the outlets cut so precise in the project box? They look real sweet :D
3 - You mentioned fuses and indicator lights, whereabouts are you plugging those into the FC-4?

And for Greg or anyone else wondering through.....

Where do yall get your projects boxes? I have looked at some at Radio Shack, looked at Junction boxes at Lowe's and even art boxes at Hobby Lobby.... None are really the right size for what I want to do and I am looking for suggestions....

Edit: I just saw Jon's post titled "Plastic Boxes"... lists a cool manufacturer http://www.okwenclosures.com/

Much thanks

Scott

[Caretaker.CCI]

Hey Scott:
I have used just about everything that you can find for project boxes. The enclosure next to the RC-4 (picture below) is what I've been using lately. I got them at a surplus house for a relatively good price. I'm not going to put anymore than two FC-4's per box which gives me 8-channels to play with. Two of these boxes would give 16-channels and remember, they can be daisy-chained together. You can also get the RC-4's on the same serial connection hence the reason for this post. I want to be able to connect these boxes together with the 3-pin hobby servo wires to daisy chain them all together. That gives an incredible amount of control from just one microcontroller (Thanks EFX-TEK)!

The outlets were cut with a Greenlee punch set (horribly expensive) but after dremmeling many D-shaped holes I knew I wanted a better way to do that. There are several other methods that could be used (all cheaper), in the end it depends on what works for you, your ability with and access to, tools and how much you're willing to spend. Just remember that (no matter what you read) there are always alternatives to accomplishing what you want.

As for this post, I've included pictures of the insides of the FC-4 and the enclosures that I am currently working with. The fuse is for incoming line voltage. It is sized according to the cumulative load that I expect to drive (4-lights in this case). The indicator light is also on the incoming AC so I know when it is "HOT". In essence, the fuse and indicator light are not "plugged-into" the FC-4. I also put an integral power supply inside the box so I don't have to mess around with keeping track of (yet another) wall-wort and one less external connection. I'll see if I can draw a schematic of how I did it. I'm not an electrical engineer (or electrician) but I think what I did is correct. If anyone knows different I would love to know about it before I get fried.

Greg

[ScaryTinker]

"Is there a convenient connector that would allow me the use of the standard servo connectors that are the usual method of connecting a Prop1 (or 2) to the outside world? "

What about about using RJ11 cables and jacks?  Use the standard servo connector on the EFX side then splice in good old telephone wire and terminate with a RJ11 connector.  If you can't make square holes for the jacks you can hang a 99 telephone wall box from the side of the enclosure.

SteveC

[menehune]

CaretakerCCI, It's a little hard to tell from the small image, but I would wire the fuse holder with the "always hot" lead on the end of the holder (the lug farthest from the cap) and the "fused" lead on the side terminal.  That way the hot wire is furthest away from the user and there is a much smaller possibility of touching a live lead. 

Panel mounted fuse holders can potentially give a shock if a person sticks a small enough finger into the holder and contacts the metal ring near the cap.  The ring also forms part of the retention mechanism for the cap so it is not buried too far into the housing.  Also if a wire breaks after the holder and you pull the fuse to check it, if the ring is hot and your finger slips touches the near metal of the holder cap and the far metal cap of the fuse contacts the ring while the fuse is being withdrawn, the fuse becomes live and can deliver a shock if you are grounded.

[Tim-M]

You mentioned Greenlee punches.  I love those punches and you're right, they are very over-priced!!  I'm trying to not buy as many Chinese made goods, but I have to tell you guys that you can find a Greenlee style punch set at Harbor Freight that is very inexpensive... finally you can afford to own a set of these punches personally.

Tim

[Caretaker.CCI]

Thanks Menehune, for the info on fuse holders. Good stuff I didn't know (or hadn't thought about). I checked to see if I had wired this up according to your directions. The point of the "idiot" light is to let (remind?) me or anyone else know that the device is connected electrically to a live circuit since there can be electricity at the duplex outlets even when the lights are not on (got to be a good joke in here somewhere!). I have no intentions of pulling a fuse (or anything else) while the unit is hot. Unplug it!

Back to the issue in this thread... I have considered the RJ11 or RJ45 but then we're back to drilling "square" holes. Not altogether impossible but not very practical. With thin metal or plastic, you could use a punch and hydraulic press (how many of you have that?). You still have to modify the cable that connects to the Prop1 (3-pins on one side, RJ11 or similar on the other).

I'm starting to get depressed! I thought someone would be able to say sure... use a (fill in the blank) and you can get it at (store x). Oh well... maybe I'll have to design it myself.

Greg

[menehune]

You don't necessarily need to drill square hole for RJ11 or RJ45 jacks. 

Both jacks have surface mount boxes available that attach with foam tape to the outside of the case.  Drill a small 3/8 or 1/2" round hole through the surface mount box into the larger box to pass the wire thru and you are done. 

If you want to get fancy or you want a lower profile mounting solution than a surface mount box (they stick up around 3/4 inch), get a keystone wall plate from your local hardware or computer store and drill a large (1"?) hole so the back mounting tabs of the faceplate stick into the interior of the box.  Drill two small holes for two #6 bolts and you are done.

Have you tried looking at USB connectors?  I do know there are USB connectors for computer cases that have .1" header pins on the cables.  It is hard to find long USB cables since the max distance is 16 feet, IIRC.
frontX has some USB stuff available.  Look at the USB A to 1x5 cable to possible hook into the servo port on the prop.  You are using the cable in a non-standard config so you need to verify the pinout of the cable and header.  I think USB cables have a small chip capacitor mounted between two of the data pins to signal USB2.0 or USB2.1 speeds.