24 switches, 24 Led's, 200ft away

this requires a design for you to approve, for a fee. Then you get a quote to make 10,000 sets. the designe fee may be $10,000 or $1 each for the first 10,000.

look in circuit cellar or nuts and volts magazines

20 years ago, there were numerous manufactures/suppliers of these devices. Often they were part of SCADA systems.

No need to re-design the wheel, it was done and marketed years ago. The technology was long ago developed. I'm looking for a present day supplier..

sadly, all the wheels are now being sold attached to carts. There are many who will sell you the carts, with horses etc, ready to roll.

By this I mean there are people who use this tech as part of their SCADA installation systems. They will not give you what they consider as proprietary information.

Doubtless there are many app notes you may be able to find that will allow you to design one of these from the start, but even those will need some programming skills these days.

this fellow may help.

http://www.tinaja.com/

Hey.. Would you believe I was just going through Don Lancaster's "CMOS cookbook" that was published by Howard W Sam's in 1977 looking for some scanner/counter chips to do the job. Found the book on my bookshelf from days gone by. I did not know that the ole boy was still publishing, he has some great ideas. Even if I don't build something up, just looking through his stuff is fascinating and can ruin the whole Sunday afternoon. I appreciate the lead.. Thanks.

Snakers

I used to build such devices for cheap remote control of multiple on/off functions. Put "Shift Register" into Google for explanations. I can't remember the actual chips I used, but they are common. Use a parallel-to-serial register at the sending end and a serial-to-parallel register at the LED end.

Thanks.. Will take a look.

Snakers

Not sure if this is the right sort of level (How much time? How much money? How many are you making?), but, what about a couple of development kits from one of the EPLD/FPGA companies.

Well, I guess it's time to bring this to closure and thank all of you for the help you have provided.

The project is for remote telephone tally lights, for a fund raising call in telethon at a local radio station that I work for. The telephones will be in a remote studio 200 feet distant from the Broadcast Mixer board.

I need to thank.....

Aurizon, who called my attention to the cost of professional design for a limited number of products.

He also reminded me that these systems are usually imbedded in SCADA and are proprietary

And he gave me a Web lead that led to a Web page authored by Don Lancaster, and I spent several hours going through a lot of goody pages.

SSCpal Gave me some leads on available shift registers, I was trying to design an encoder from counters and logic from scratch. I had not thought of using shift registers so I thank him.

Randal mentioned PLD and EPLD/FPGA technology, a system that was developed after I retired from circuit design. I have seen these chips in the catalog but gave them little notice. At 80 years old, I had to do some head scratching, but after a couple of days of study, I think I have a handle on it. I truly enjoyed reading up on it but probably will not use it because I do not have the construction time to learn the programming.. May go back to it later.

The bottom line is that I have made a lot of drawings and ordered some discreet shift register (dip) chips from Mouser. I have a cad type circuit board program, lots of copper board and Ferric Chloride. Once again, I thank you all for the help.

Snakers

maybe if you learn something about microcontroller such as AT89S51, your problem will be solve. with 1 microcontroller as a transmitter and 1 microcontroller as a receiver you can control more than 24 led with 2 pair comunication. But to built this circuit need more programmer skill. How many your order?

Re: 24 switches, 24 Led's, 200ft away 10/15/2007 11:42 PM

agus kuds

Maybe I do know something about microcontrollers, I have been working with them for 20 some years. Do you want me to design one for you ???

What right do you have to question my knowledge?

The Microcomputer, brute force approach was considered. It was set aside as a stupid over-kill solution for this application, and for your information, microcomputers can operate over a single pair?

Maybe if you would learn to speak and write the English language a little better you could communicate better. That includes knowledge of good grammer.

Did you notice in the original question I mentioned American Source ? I expected people to address me in English.

Let's drop this here...

Snakers

Since this is a broadcast studio, it need not be wireless. Seems to me that this could be made simply by running #24AWG 25 conductor cable, if the LED's are low power (20 mA e.g.).

You are Correct, and this is how we have done (within our studio building) in in past years with about 10 telephone positions, however we are now going to 24 telephone positions requiring them to be remotely located in the building next door.

The cable loading is complicated by a switching system to busy out the un-maned phone lines so that the telephone circulator will skip these positions. and each phone station also requires a Cat6 computer connection that (because of the configuration) is not adaptable to a remote hub or switch, so you can visualize the required complex cable system laying on the ground between the two buildings. The phone tally lights may be required at several different management locations.

We also use a phone logic of the voltage on the phone line. Less than 1 volt means the line has been shorted down (busied out), Over 30 volts (central office voltage) means the the phone is on hook waiting for a call and any voltage between these ranges means that the phone is in use.

Truthfully, it looks like 2 shift registers with a common clocking pulse is the easiest way to go. It will take a little time building it up but nothing new in our business.

I see you list your location as Orlando.. We may be neighbors, this operation is in St Pete.

Do you need power also down the same set of wires?? I once (about 1982 or 3) saw a scheme for connecting a keyboard to to a computer using a single pair. The serial data was AC coupled onto the cable at the keyboard end, and AC coupled off the cable at the computer end, while power flowed in the other direction. There was some resistance in the power line at both ends. It has been many years since I have even thought about this but...

Imagine a 5v zener regulator to power the keyboard. At the computer end we will supply 12 volts. A dropping resistor is required to drop the difference of 7volts. What if you put half the resistance at the computer end, and half the dropping resistance at the keyboard end. This gives you some impedance to couple the data onto.

Bob Nixon (the fellow who came up with the scheme) also published it in EDN under DESIGN IDEAS at approximately the same time (82, 83). I wonder if EDN has back issues available on line?

Anyhow, I thought this might be of interest.

Bill

Thanks Bill, Yes I am aware of that configuration, and It would work good, except there is no need for it because I have power available at both ends, in fact they are both fed from the same pole transformer bank.

For interest, it is also interesting to note that the studio is on Phase "B" and the other building is on Phase "C". so my thoughts of using the power line for the slow scan sync pulses for the clock becomes more complicated with the 120 degree phase shift. It may require a third wire for the clock.

I do thanks you for your comment, I have had some goood help from the group on this problem.

Trivia.. Telephone companies put the central office battery on line to power your phone and your phone communicates with an AC signal over the same pair, (same principal)

Snakers

I'm sure you've got the problem solved now, but just another piece of trivia: I still have several working examples of 1930's era Supervisory Control systems, which work similar to the old pulse-relay central telephone switch. When one contact fails in a system with 10 contacts each on 84 relays, it's a real pain to troubleshoot, but it does work over 1 pair!

Of course, you could just buy a pair of cheap plcs on ebay & connect them peer to peer with modems.

Yes, I have worked on those Westinghouse relay SCADA systems with North Electric relays. Relays 1,5 and 7 were the line encoding relays. We had about 12 of them and another 15 GE systems, the 3 later Quindars and the Harris were solid state. After a while you learned to listen and read the relay click codes and knew what relay to check.

You are going back a long ways. I worked on them in 1948

Snakers