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real simple problem, but I can't find the solution.

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1997 GA16DE

New Member
hey, I'm a newbie on this forum but I got a quick question. I'm currently working on a small tail light project on my car. I am using a 1157 dual filament bulb, but the lower wattage filament is being used for the night time lights.

The higher wattage filament (commonly used for the brake and/or signal) is what I'm looking to work with. I have a 12VDC signal for my brake and a pulsating 12VDC signal from the blinker. I want to run both signals to the same filament so that each one alone will be able to power the bulb but when both are on at the same time, the signal will be canceled and the bulb will not light up.

in simpiler terms, I have 2 12Volt sources:
0+0=0----------0+1=1
1+1=0----------1+0=1

The components need to run on 12VDC (14V to be safe), and I will be using a relay, so the current draw will be small.

TIA
~Justin
 

Phasor

Member
What you have just described is an "exclusive OR" gate. For this purpose, you can use the 4030 chip (Quad 2-input ExOR).

I've only got a few minutes to spare now, so I'll post a schematic later (or maybe someone else can...)
 

1997 GA16DE

New Member
cool, thanks. Will the chip work on a 12-15VDC supply?

BTW, where's the best place to get a 4030 chip? I saw it in an old RS catalog, but from the looks of it, they don't have them anymore.
 

1997 GA16DE

New Member
well, it's not exactly what I'm looking for, I'm looking to concentrate on each side seperately. That seems a bit more complicated than what I really need. I'm running the bulb off a relay anyway so I won't need to run the same current straight to the bulb and possibly fry the other components.

here's a diagram (minus the 4030 EXOR) :

I figured I will need diodes on the incoming wires b/c the blinker signal switches when off, as I found out earlier today, same goes for the brake.
 

1997 GA16DE

New Member
BTW, no offense, but the writing is pretty difficult to read. I can get through the diagram and come up with a working model, but I'm gonna need to have the parts listed out better b/c I'm no expert at this.
 

Phasor

Member
You've basically got the right idea with your diagram, except that I don't understand why you've put the diodes in there. Also, you will probably need to drive the relay via a transistor - CMOS chips generally can't source enough enough current to drive relays.

The datasheet for the 4030 is here:

http://www.electro-tech-online.com/custompdfs/2003/07/CD4030CPDF.pdf

I was thinking just now, that since you already have 2 relays installed, you could do this project entirely in relay logic - you just need one extra relay. Here, I have drawn it, as a ladder diagram: (I assume that, if you have the brakes and a blinker on, you want the light on the signal side to flash, and the other one to stay on. Is this correct?)


Take your pick :wink:

PS In case you have never encountered ladder diagrams (aka detached notation), you just have to know that contacts labelled "A" are operated by relay "A", contacts labelled "B" are operated by relay "B", etc...
 

abhishek singh

New Member
hi,


here is the diagram, please calculate and select componants according to your need.




if this image looks blur , zoom it out.


abhishek
 

1997 GA16DE

New Member
Phasor said:
You've basically got the right idea with your diagram, except that I don't understand why you've put the diodes in there.
The diodes are there b/c in my car, instead of the source switching on/off, it switches from positive to negative. The diodes will just simplify things a bit.

Phasor said:
Also, you will probably need to drive the relay via a transistor - CMOS chips generally can't source enough enough current to drive relays.
If that's the case, should I run the bulb off of the transistor, or would that be too much on the transistor?

Phasor said:
I was thinking just now, that since you already have 2 relays installed, you could do this project entirely in relay logic - you just need one extra relay. Here, I have drawn it, as a ladder diagram: (I assume that, if you have the brakes and a blinker on, you want the light on the signal side to flash, and the other one to stay on. Is this correct?)


Take your pick :wink:

PS In case you have never encountered ladder diagrams (aka detached notation), you just have to know that contacts labelled "A" are operated by relay "A", contacts labelled "B" are operated by relay "B", etc...
I think I'll work with the 4030 chip b/c automotive relays are just too big to have 3 all on one side. Besides, I don't have the relays yet, I have to stop at discount auto or something to pick them up.

I'll try to post a diagram of what I'm thinking of doing and you can help me out correcting it.
 

1997 GA16DE

New Member
ok, here's pretty much what I want to do, this is what I take from what I can see, but you'll have to correct me on this diagram b/c I'm sure I missed a bunch of stuff:
 

1997 GA16DE

New Member
ok, here's an update of the diagram. I need some input ASAP, plz tell me what's right, what's wrong, what I need to include, and what type of transistors, resistors (if I need any), and diodes that I should use.
 

Klaus

New Member
Ask a simple question and what do you get? Lots of answers of varying degree of complexity :)

No need to use logic chips, these are prone to failure in automotive applications anyway.

Here's what you do: ( sorry, it'll have to be a word picture as I do not know how to do the other kind)

You need two relays which have SPDT ( changeover) contacts. You use only the N/C (closed when UN- energised) contacts.

Brake to one relay (1) N/C contact, blinker to the other relay (2) N/c contact. Other contact end of both relays are commoned and go to your lamp.
Now the logic : relay 1 gets powered by blinker, relay 2 by the brake.
So, whats happening is, each time a signal, brake OR blinker, arrives the other input gets turned off by the relay - bulb lights on either signal.
If BOTH signal arrive then BOTH relays turn off - bulb unlit.

As the blinker is an intermittant signal you might just get a very brief flash from the lamp, depending if the relay turns on faster than the filament lights up or not in the case of both signals being present.

Klaus
 

Sebi

Active Member
For proper work definitely need power for IC, two pull-down resistor for inputs, base components for transistor, and snubber-diode for relay.
 

1997 GA16DE

New Member
Klaus said:
Ask a simple question and what do you get? Lots of answers of varying degree of complexity :)

No need to use logic chips, these are prone to failure in automotive applications anyway.

Here's what you do: ( sorry, it'll have to be a word picture as I do not know how to do the other kind)

You need two relays which have SPDT ( changeover) contacts. You use only the N/C (closed when UN- energised) contacts.

Brake to one relay (1) N/C contact, blinker to the other relay (2) N/c contact. Other contact end of both relays are commoned and go to your lamp.
Now the logic : relay 1 gets powered by blinker, relay 2 by the brake.
So, whats happening is, each time a signal, brake OR blinker, arrives the other input gets turned off by the relay - bulb lights on either signal.
If BOTH signal arrive then BOTH relays turn off - bulb unlit.

As the blinker is an intermittant signal you might just get a very brief flash from the lamp, depending if the relay turns on faster than the filament lights up or not in the case of both signals being present.

Klaus
Well, not that I don't appreciate all the opinions, but I think I want to go with the 4030 chip. It's small and responds a bit quicker than a bunch of relays, besides, I have no clue where I'm gonna find a N/C 12V relay.

Can someone just please give me the diagram to hook it all up?
 

Klaus

New Member
Dont go looking for N/C relays. look for a 5 terminal relay, 2 for the coil and 3 contacts. one contact is common, one is N/C and the other N/O.

Quite common relays, these with 12V coils.

Good luck with your EX OR gate solution.

Klaus

P.S. if you can draw fancy flashing diagrams you surely can draw up what I posted. :p
 

1997 GA16DE

New Member
Klaus said:
Dont go looking for N/C relays. look for a 5 terminal relay, 2 for the coil and 3 contacts. one contact is common, one is N/C and the other N/O.

Quite common relays, these with 12V coils.

Good luck with your EX OR gate solution.

Klaus

P.S. if you can draw fancy flashing diagrams you surely can draw up what I posted. :p
Well, even though I'm good with CAD, I'm not that great in electronics or drawing something I've never seen before. I've never even heard of a 5 terminal relay. I've seen a 6 terminal relay, but I've never really bothered to wonder how they work. I'm sorry, but I still don't have much to go by.

I'll try drawing out the relay and seeing what to do with it.
 

1997 GA16DE

New Member
Sebi said:
For proper work definitely need power for IC, two pull-down resistor for inputs, base components for transistor, and snubber-diode for relay.
cool, that's just what I'm looking for. few questions:
  1. what kind of diodes should I use?
  2. I would assume both of those resistors going from 1 to 7 and from 2 to 7 are 1k ea. correct?
  3. what about the 3k3 one? is that supposed to be 3.3k?
thanks
 
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