Electronic Switching Device

[Generatorman]

Hi All.
After searching the 'net high and low, I'm kinda hoping I landed in the right spot. I work in emergency power generation for a living, and I'm kind of the "go to" guy for specialty work. I am currently up against a project that I have not a clue what to do. Here is my dilemma:
I need a device (even if I have to make it) that will switch 30 pin ribbon cables from one to another, in other words I have a "main" and I need to switch from "slave 1" to "slave 2" making and breaking all 30 pins. any ideas?

 

[Generatorman]

Silly me...

I forgot to add I need it to switch via a +24Vdc trigger wire or dry contacts ( I have both available).

 

[mneary]

I would investigate DIP relays. They are available in configurations up to 4PDT. A good example is allelectronics #rly-503.

 

[Generatorman]

Thank you. Greatly appreciated.
I will simply build a board with a IC Regulator and three headers utilizing 8 of those...I think I can handle that. Thanks much for your input.

 

[mneary]

You can put 4 of the relays in series with 47 ohms and no regulator is needed. Just remember that this arrangement will need 160 mA.

A regulator with 8 relays in parallel will have to supply 640 mA and will get hot.

 

[Generatorman]

Thanks.
My source voltage (24Vdc) is not a stable voltage as it will reach 27-29 Vdc when the DC Alternatorr is running. will this matter much? I guess I need to review "P.I.E" again, and do the math.
I ordered all the stuff from all electronics. How hard is it to make a PCB? I included a perf board with my order...but if it can be done by a novice like myself without the use of "jumper" wires...that would look much better for the application.
Thanks for all the help on my first little project....I am grateful.

 

[crutschow]

If you want to make a PCB there are several companies such as **broken link removed** that provide you free software to generate the artwork for the board and then can fabricate the boards for you. You can generally get several small boards built for under a $100. You can buy board mounted connectors to go along with the DIP relays so you would have no jumper wire connections.

 

[Diver300]

Thanks.
My source voltage (24Vdc) is not a stable voltage as it will reach 27-29 Vdc when the DC Alternatorr is running. will this matter much? I guess I need to review "P.I.E" again, and do the math.

Relays are not that critical on the supply voltage. A 24V relay would be fine on a 24V vehicle system even at 28V with the alternator running.

Using several relays in series will be much the same. The voltage will be evenly spread across all the relays (and the resistor if fitted). A higher voltage make them all get a little warmer, that is all.

 

[Mikebits]

What are the signals your switching? How many amps and at what voltage will be going through the contacts?

 

[Generatorman]

WOW! Thanks for the replies.... This place is awesome. I was kind of scared of being blasted for being such a noob.. but you all have just been great!

I am going to go the route of using the free software then getting three boards made. I think it will be much more professional looking.

As for the usage, I am installing a redundant main control board on a emergency generator controller, all of the signals are carried through a 34pin ribbon cable and are either 5v digital signals or 1.1V digital signals....very low amperage.
I deal with 12 & 24 VDC and even larger AC relays all the time, but I have never dealt with DIP relay's...man these things are TINY!!

 

[Mikebits]

My concern here, are the circuit boards on either end of the connectors tolerant to hot swapping? Also relay contact noise and bounce may have adverse affects on digital circuits. Since I do not know the circuitry of the boards it is hard to say. Since all the signals are low level, perhaps solid state relays would be better.
Here is a link to one type.
**broken link removed**

 

[Generatorman]

The boards have individual DC power circuit(s) that I have switched via a 15A "Ice Cube" relay and is electrically locked out during an actual operation..hence there is no way to hot swap the boards, nor can they both be active at the same time. There must be a power down in order for it to transfer to the secondary board.

 

[Mikebits]

In that case Your relay rig sounds easier. Sounds like your good to go