Interesting Relay Project

I want to make a traffic advisor (like you see under the lightbar on a police cruiser). I can figure out how to make the configuration of relays for each direction sequentially (1 relay per light per direction), however, is it possible to utilize 1 set of relays for both directions? Confused? :)

A traffic advisor is a series of lights that "points" in which direction the traffic should flow/go. If you can picture a highway traffic arrow, this is basically the same thing.

Example, with (4) lamps:

symbol key: 

[] = light on

- = light off

Advising to the right:

[] - - -

- [] - -

- - [] -

- - - []

(then repeat)

Advising to the left:

- - - []

- - [] -

- [] - -

[] - - -

(then repeat)

The question at hand is not how to build the unit, but how to utilize one set of relays for both directions, with just a flip of an on/off switch, as well as a direction (right or left) switch.

If this can be achieved, I will certainly benefit from the knowledge, as well as make another contribution to the website. This would save me a lot of $$$, and my savings would be put back into information like this, rather than profit to a business.

Thank you in advance!

Joseph M. Tortorelli

Do you have something now with two sets of relays? What other components do you have incorporated? What are you using to provide a separate pulse for each lamp? Are you starting from scratch and trying to make this entire project out of relays and two on/off switches?

the12volt • Support the12volt.com

Do you have something now with two sets of relays?

A: No, I have nothing thus far. 

What other components do you have incorporated?

A: I plan on just having the relays and a switch... diodes, as needed, to regulate back-feed.

What are you using to provide a separate pulse for each lamp?

A: The correct value diode to keep each relay/lamp on for the amount of time I want it on (ie: interior illumination after shutting the ignition)

Are you starting from scratch and trying to make this entire project out of relays and two on/off switches?

A: Yes, starting from scratch. If needed, yes, two on/off switches. I was thinking something more along the lines of a switch for on/off and another switch for pattern (left, right). If needed, I would do one switch for left pattern on, and one for right patter on.

Thanks for the prompt reply, admin!

you would probably want a clock circuit to initiate each change, although you might be able to use a bunch of capacitors and time delay. How much current draw do you want to be able to draw, 100 mA, 10 A? Although it probably could be done with a bunch of relays (i assume you plan to use 8), i would probably go with an electronic driver circuit using a bidirectional binary shift register or something of that sort. that way you would only need 4 relays, and could easily change direction and even the speed of the shifting. I dont know just my ideas, but then again im always biased to using solid state electronics as relays have a lifespan .

 Although if you just want relays and switches i think it can be done, but i dont see how it could be done without some capacitors too.

Your circuit can not be made with just relays, diodes, and on/off switches as you described. BTW, a diode will not limit the amount of time a relay or lamp will stay on. If you had an output that provided an on/off pulse for as long as the power switch was on, it would be possible to create a loop with relays that would provide as many lamp outputs as you need for one direction and would advance from one lamp to the next with each successive pulse, however you would still need an identical configuration for the opposite direction making it fairly cumbersome and somewhat pricey compared to some light kits that you can purchase for around $20.00 or so and build yourself.  There are some on this page that I found doing a search for "sequential light flasher" that you could easily modify to do what you want: http://www.amazonelectronics.com/amazon/catalogue/c3-3-6.htm 

the12volt • Support the12volt.com

Actually, those kits are great.  I'm thinking either the CPSPB20 or AA421 is the kit I'm going to go for. They both do the same, however the AA421 is more geared towards 12v output. My only issue is that all of the 10 patterns for the 8 bulbs direct the lighting to the right, which means I'd have to use 2 different sets of 8 relays (one for each direction) and a SPDT switch (for change of direction) unless there is a way to utilize SPDT relays.

Thanks for the link!

jt

ps:

You are correct. Diode was the wrong term... I don't know how that slipped. I meant capacitor. Thx.

Hmmm, 2 things, after thinking about it for a day:

#1: I'm just going to use a 3-position switch, with the middle position being "off", and each side being the pattern/direction.

#2: I'd hate to use standard 30A or 40A bosch relays for simple <5A lights. I'm having a hard time trying to locate a supplier of mini-relays. Either I'm looking at the wrong things, or they are just damn expensive! Should I be looking at anyplace in particular, or should I stick with the big ol' relays? Thanks.

- jt

More info since last night...

#1: I found some micro-relays in an old MCM catalog... PC mount ones, but I'm sure I can figure something out. I just have to double check on availibility.

#2: I understand the most common diode is a 1A (1N4001/L), however, what should I look for, say, if I want a diode on each lamp, assuming it draws 5 or less amps/ea?

Tanks! :)

- jt

I think I found the correct value(s) for the diodes I need. If someone could just verify this, I should be all set. Right now, I'm looking at either:

• 1N5400 (50v / 3.0A)

                           or

• 6AO5 (50v / 6.0A)

The 1N5400 should be fine, because I'm running only a quarter of the voltage, which should allow for a higher tolerance for amperage, correct?

Thanks for all the help!

jt