Help needed on multiple relays

[TheScavenger]

I am building a project for my business and need some input on relays. Back 10 years ago I was able to do this but I have not been using relays and I am getting rusty. I need to set up a simple relay system with a push button switch to set the relay. When the relay is activated the relay will turn something on. The problem lies where I have 4 switches and if one is triggered I need the rest to become inactive and not work.

My end goal is to put this to ladder logic and control an Allen Bradley SLC 150 I bought off of ebay. I have the programming software from work. I tried to learn the language and make it happen but I am at a brain jam. So I thought if I go back to basics with the wiring diagram of a relay system then it might be easier.

Can any of you help?

Dave

 

[jraef]

What do you mean by "inactive"? In it's simplest form, if you turn the relay on with switch #1 and it stays on, switches 2-4 don't really do anything else since it is ALREADY on.

"Venditori de oleum-vipera non vigere excordis populi"

 

[TheScavenger]

I guess I was not clear. All 4 switches turn on something different. I want to be able to hit any switch and turn just that object on. So only one object could be turned on at a time until it was reset.

I am making a game so when I ask a question the players can ring out. When they hit the button a light turns on so I know who was first. After the first button is pushed the rest of the buttons can be hit as many times as they want and will do nothing.

Does that make better sense?

 

[jraef]

Jeopardy!
Yes. Just make sure each relay has at least 3 NC contacts and one NO contact. Wire each of the NC contacts in series with each opposing coil circuit. Wire the NO contact in parallel with the push button NO contact to the coil of that relay. When the button is pressed, it energizes the coil and seals itself in with the NO contact. The NC contacts will also open up and lock out the coil circuits for all of the other relays. so pushing the other buttons has no effect.

The only problem left is how to reset. You could easilly put one master button in series with all of them at the beginning of the circuit, or open up the neutral side of the circuit so all 4 coils drop out.

"Venditori de oleum-vipera non vigere excordis populi"

 

[TheScavenger]

okay Thanks. I am trying to draw this up at this time. I think i need another cup of coffee.

So what you are saying is each player position needs a total of 3 NC Relays and 1 NO relay and one pushbutton. The 3 NC relays will cut the power to the other 3 player position push buttons. The NO will cut the power to that persons push button.

so for 4 player positions i would need a total of 16 relays- 12 NC and 4 NO. Correct?

BTW thanks for your help

Dave

 

[jraef]

Well, you need that number of CONTACTS, but generally there are more than one set of contacts on each relay. If you are using the inexpensive "ice cube" style relays, the ones with 8 pins have 2 sets of DPDT (Double Pole Double Throw) contacts, so one set could be the NO, the other set the NC. Then use a second relay and only the NC contacts on that one. In that case, you would need 2 relays per player for a totoal of 8.
If you use the ones that have 11 pins, they have 3 sets of DPDT contacts, and if they have 14 pins there are 4 sets, which would make only 1 relay per player. 14 pin relays are sometimes difficult to find in stock however.

It may also be easier for you to look for what is called a "machine tool relay" available from an industrial electric supply house, because they can come configured with 1 NO and 3NC all on one relay.

"Venditori de oleum-vipera non vigere excordis populi"

 

[TheScavenger]

well this is new to me the only relays that i have worked with were for car audio. 1NC and 1NO connector. I have given up on the relay thing I just cant seem to get the wireing drawn up.I am trying to find someone now that can program a SLC 150 PLC.
I am not getting that far that way either.

thank you for all your help

 

[dhwilliams]

If you can do a bit of electronics, here's a link to a suitable circuit -

http://www.zen22142.zen.co.uk/Circuits/Misc/quiz.htm

 

[TheScavenger]

thank you that is what i am looking for.

 

[TheScavenger]

This is probably a stupid question but I do not understand part of this diagram. The VCC input. Could this be the positive input from a computer power supply? I could then take the output instead of using LED’s they could be used to switch on a standard relay so I can run 110V lights. I do not know much about the current draw of a relay and what the IC’s can handle. I saw somewhere online that the IC4013 can hold 700mw. I do not know how much juice a coil of a relay will use. I never had to worry about that before.

Last question on the 1k resistors will I still need them if the output is a relay? Or will the resistors have to be a different value.

This looks like a better way to go then the PLC I am trying to program.

Once again thank you all for your help.

Dave

 

[TheScavenger]

Ok I figured out some stuff. After about 5 hrs of reading I will need a transistor at the end of the circuit to power the relay coil. I am having a hard time figuring this out this is supposed to calculate the transistor needed for a relay coil. It just gets me lost.

The transistor's maximum collector current IC(max) must be greater than the load current IC. Load current IC = supply voltage Vs
Load resistance RL

The transistor's minimum current gain hFE(min) must be at least five times the load current IC divided by the maximum output current from the chip. hFE(min) > 5 × load current IC
Max. Chip current

Choose a transistor which meets these requirements and make a note of its properties: IC(max) and hFE(min).
There is a table showing technical data for some popular transistors on the transistors page.

Calculate an approximate value for the base resistor: RB = 0.2 × RL × hFE or RB = Vs × hFE 5 × IC and choose the nearest standard value.

Finally, remember that if the load is a motor or relay coil a protection diode is required

This is the relay that I found that I think will work.

http://www.jameco.com/webapp/wcs/st...toreId=10001&catalogId=10001&productId=121663

Can someone translate the top and tell me what transistor and resistor I would need to activate this relay. Also

 

[dhwilliams]

It looks like you plan to run the whole circuit off 12V, which is OK, so the relay coil will take about 36mA (I = V/R)and if you remove the LED but leave the 1K resistor the chip will supply just under 12mA so you need a gain of 36/12 * 5 (the 5 is because the quoted gain of the transistor, its h_FE, is the small signal gain not its dc gain). So you need h_FE=15. I would use about 30.

To safely handle the coil current the transistor's I_C(max) should be about 100mA. Just connect the 1K resistor to the base of the transistor for each output.

As you can see from the diagram below, the transistor is an NPN.

The diode could be 50V, 1A (mainly because this is such a common spec - it's not critical, it just needs to be greater than 12V and able to handle the current generated when the coil is switched off)

 

[jaysscholar]

I have a couple of questions


Do any of you have a clearer schematic?

How excatly does one relay shut off another? Do you wire the initial pins together between relays?

I'm not understanding. sry.

 

[nbucska]

I suggest use a cheap microcontroller (e.g. PIC)
it can be less than a buck !!

<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[danishmemon35]

yes this is alright but i think so that u can also use simply a personal computer and use parallel port interfacing using C++ programming for this one and this will work more suitably then any thing else

 

[fangas]

Hi Jay,

Maybe I'm reading this wrong, but it appears like you want this to eventually end up in the SLC150 you have.

If so, try this as a start.

---] [----]/[----]/[----]/[-------( )--
| 100 | 101 102 104 ?1
| |
|-] [-|
?1
---]/[----] [----]/[----]/[-------( )--
100 | 101 | 102 104 ?2
| |
|-] [-|
?2
Just repeat each rung as needed

Each switch will turn on only 1 output and turn off all other outputs, multiple switches will turn off all outputs and cycling power will turn off all outputs

100-104 will represent your switches as inputs and ? marks your relays as outputs (sorry, can't quite recall the output address in the SLC)

Ed