Common return for. L E D’s

Hi All.    I have wired an indication panel to work with manual points, so far I have tested the wiring using a battery.So far so good, I have a wall wart ( mains adaptor ) wired into the layout, but I now have to do the common return.
I am using a “ Terminal Strip “ on the panel connected via a scart cable. But how do I wire the common return to the LED ‘s via the scart without illuminating all the LED’s simultaneously . When the Scart is used in the conventional way there is an Earth wire connecting the TV and Video or WHY via the metal part of the plugs, can I utilise this wire?
Please advise.  Kevin

I highly recommend reading Mr Lamberts excellent advice on his electrical page. He covers most simple wiring in a very easy to understand way. I am sure a SCART is not much different to other multi-way connectors - choose a wire for your common return and follow Mr Lamberts diagrams and you wont go wrong.  
http://www.brian-lambert.co.uk/Electrical%20page%202.html#LEDs

IanLMS

Just found this link which might help select the right pin.

SCART - Wikipedia


Ian

Hi Ian.   Thank you for your reply. I have just been following the example of Telecom men, that is finding the correct wire with with a battery/buzzer combo. I looked at the Brian Lambert link, as usual it is beyond me, and I wasn’t sure what the resistor was for. With me i’m Afraid say it is a bit hit and miss.  Best wishes. Kevin

Trying to put it in laymans language…

If you are using standard LEDs without the resistor then as soon as you connect the power then you have dead LEDs.
A standard LED will use about 1.8V, if you using a 5v or 12v supply then the resistor takes the rest. Without the resistor it gives to much voltage across the LED and therefore too much current so you fry the LED.

You can buy 5V or 12 V LEDS, these just have the resistor built in..

Hi The Q.    Thank you again. AFAIK the LED’s that I am using have a resistor Built in “5mm 12volt”. And I thought that they were all the same .    Best wishes.  Kevin

If the resistors are built in and rated for 12v then as long as you only supply with 12v, you should be good. Mr Lamberts drawing just show the resistor separate. You will have a long and short leg on the LED. The long leg will have the built in resistor, so you call this Pos +. The short leg will be considered Neg - which you would use for the common return. You can run them in a series, again just follow his advise and you will be good to go.
It all depends on how you intend for the LED's to be activated. I cheated, and purchased point indicator panels with supplied LED's from Microminiatures. These took care of the wizardry between activating the point and the LED indication panel: http://www.microminiatures.co.uk/acatalog/Model-Rail-Points-Position-Indicator.html

If you are taking the supply from the track itself, again Mr Lambert covers this in detail. 

Ian 

Thanks for the heads upon this product . I have just ordered one as a try out .

I had previously bought two 8 way dcc units offering 16 point cdu,s and connections for appropriate LED connections .
Out of the 16 Ways  one worked , the cdu,s got hot took a while to recharge and one of the 8 way units buzzed quite happily . I think "not fit for purpose " is the current phrase for this stuff.

Hi Ian     Thank you again, as I said at the beginning of this thread I only have four manually operated points on my plank, all operated by WIT, and I keep forgetting to throw the points. My “ Bodge Job “ is only to aid my memory.The lights are operated on their own 12 volt supply. If I was an expert??? I would like to create a “ Micro Panel”, on 
a sheet of Perspex , rather than a plywood box.   Best wishes.  Kevin

I have 32 points and when DC used the boards from Microminiatures wired through the Peco point motors. So easy and they have memory. Just lots of wiring. When i went DCC i wanted to operate the points via my tablet so got 4 DCC Concepts ADS8FX. However every time i get a short i would have to reset every point and the panel lights dont indicate direction of point just that it was activated. I am swapping one 8 way for the ADS8SX which is an improved version and has memory for my hidden sidings. I am not sure how u would wire LEDs for WIT. Probably via a micro switch or slide switch so the LED would power up depending on the route it was set to.

Hi Ian.    As a non electrician . I didn’t know if my idea would work. As you undoubtedly know DPDT Slide switches have two rows of three contacts , I was using the three on one side, the other three being redundant . Redundant until the idea came to me to wire them to LED’s, and it worked, but they all didn’t illuminate hence the “ common return “ question. But now I am using the Scart socket and cable ( previously I was using “ Sub miniature.D “ cable and sockets  with crowded contacts and not easy to solder.).     Whereas the scart has more room to manoeuvre.                Best wishes

Looks interesting and ability to use a SCART offering 20 cables in a nice tight space would be great. I am not an electrician either and all i know is what I have learnt from Mr Lambert and good old trial and error!
Someone on here must have wired their WIT points to an LED panel using a DPDT switch so I am surprised they haven't chimed in yet.

Someone must have also used a SCART as a simple means of connection.

Ian

IanLMS wrote:

Looks interesting and ability to use a SCART offering 20 cables in a nice tight space would be great. I am not an electrician either and all i know is what I have learnt from Mr Lambert and good old trial and error!
Someone on here must have wired their WIT points to an LED panel using a DPDT switch so I am surprised they haven't chimed in yet.

Someone must have also used a SCART as a simple means of connection.

Ian

Hi Ian.   Could that “Someone “ be me??? I had written a thread on the subject a while ago ,but, I could not find it until recently , after looking for “Mimic Panel” in the word search on the Home Page.    Best wihes

Good luck with the venture - I wish i was an electronic expert sometimes! Good luck with the SCART and would be interesting to see a diagram of how you wired it up to LED's via a DPDT using the WIT method for the points. I have a few spare SCARTs lying around that I could possibly put to good use.

[user=1801]Passed Driver[/user] wrote:

IanLMS wrote:

Looks interesting and ability to use a SCART offering 20 cables in a nice tight space would be great. I am not an electrician either and all i know is what I have learnt from Mr Lambert and good old trial and error!
Someone on here must have wired their WIT points to an LED panel using a DPDT switch so I am surprised they haven't chimed in yet.

Someone must have also used a SCART as a simple means of connection.

Ian

Hi Ian.   Could that “Someone “ be me??? I had written a thread on the subject a while ago ,but, I could not find it until recently , after looking for “Mimic Panel” in the word search on the Home Page.    Best wihes

Kevin, just hit the 'Topics I Started' button from the menu under the picture of the week:

My Own Posts      Topics I Started      My Photos

It's much faster!

Bill

Hi Bill    Thank you for your reply . I did the “topics I started” but didn’t go back far enough. The toughest part of the project was “ buying over the counter” the scart socket.     Best wishes.  Kevin

Hi Ian    The WIT is connected to the switch , just drill a hole in the switch, and another hole in the baseboard just in front of the switch, pass the WIT through the hole and up to the point. As I said the three spare contacts are wired to the contacts on the back of the scart socket ( 1 reversed, 2 positive input from 12 volt supply which is fed to 1 & 3 depending on the position of the points), 3 normal). Then remove one plug, strip the wires and connect the wires to the LED ‘s.   Best wishes