need electronic relay help

[andy19422]

I am working on a project that has an Orange and Blue light which will be either LED strip or EL tape. I would like one to be on for five minutes or so then to switch off then the other come on for the same time in a repeating pattern. Is there a relay timer for sale that will do this?

 

[vixr]

andy19422, remember that most relays have a Normally Open as well as a Normally Closed contact...all you need to do is build an on timer using a CMOS4093 IC. The on time repeats every five minutes keeping the NO contacts closed, switches off after 5 minutes closing the NC contacts. The circuit I have in my head would be adjustable to anything from 1 minute to up to 25 minutes or so...I could post a schematic, but I can only give about a 90% certainty that it would work without tweaking. Do you have the power supply input voltage in mind already? I guess this all assumes that you would build it yourself, parts cost is minimal 5 bucks at the most. Shipping is what seems to be expensive these days.

 

[star-art]

The relay will "click" each time it activates. You could look up a circuit for a "railroad crossing signal" and this is the same basic thing, except you would change the timing.

Many people are not aware that relay coils cause sparking when the relay is switched off. This may or may not be a big deal, but it can cause premature wear on the contacts over time. You can add a couple extra components to eliminate this.

If you don't want to deal with that, and you don't want to hear any clicking sounds, you can also wire the circuit using transistors so it is all electronic.

 

[vixr]

nevermind

 

[Martimous]

For what it's worth, there are also solid state relays that do not have coils and contacts that click. They have solid state switches inside; Avago has some that come in DIP PC-board mount packages. They're a couple of bucks through a distributor like Mouser, Newark or Digi-key. There are also small reed relays that the "click" is very quiet that also come in small packages. I have more data if anyone is interested.