Alternating Logic Circuit Assistance for Relay Circuit

[tranceracer]

As a result of purchasing the wrong relay from Mouser, go me thinking about a low power relay ckt.  But I need a little help with the basic logic ckt.

Here's the background.  By mistake purchased a dual coil DPDT relay that changes the switch position by powering a separate coil to switch the relay. 
http://www.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMs3UE%252bXNiFaVF12THBPgwXPw2JypUvY4sk%3d
In other words there's no spring to normal the relay when it's de-energized.  The status of the relay stays in the last position.

So, I was thinking if there was a simple ckt that alternates two pins High and Low between each clock cycle, the relay coil doesn't have to stay charged and thus saving valuable current.

In other words:
clock or switch cycle 1 would put pin A HIGH and pin B LOW.
end of clock cycle, pin A goes LOW

clock or switch cycle 2 would put pin A LOW and pin B HIGH.
end of clock cycle, pin B goes LOW

clock or switch cycle 3 would put pin A HIGH and pin B LOW.
end of clock cycle, pin A goes LOW

clock or switch cycle 4 would put pin A LOW and pin B HIGH.
end of clock cycle, pin B goes LOW
etc..

Initially I was thinking the 4049IC would work but it keeps each coil energized. I want to de-energize each coil after each switch.

Can anyone assist to find a simple ckt that does the above? 

For enquiring minds, I purchased a boat load of these swtiches, way back, thinking that these relays were regular single coil DPDT relays. (DOH!  ).  BUT for those of us who use relays, my huge $$ mistake may result a much more efficient relay switching platform.   

I'm currently searching the web for ways to use the 4013, AND, NAND gates to get this result.  I'll post back if I find anything.

Thanks is advance!

[R.G.]

When you're messing with relay switching (among a bunch of other things!) it's nearly always better to go read GEOFEX first.

See http://geofex.com/FX_images/ltchrly.gif for how I did an alternating-action relay circuit based on a simple momentary switch. Might help to read "Relays for Audio Switching" http://geofex.com/Article_Folders/relays/relays_for_switching_audio_signa.htm from 2001, too.

I think that particular snippet has been there for about ten years now.

[tranceracer]

RG,
A Huge thanks for the response.   I'm actually using this great inverter ckt for my relays and that schemo (http://geofex.com/FX_images/ltchrly.gif ) is what I was going to use for the dual coil relays that I bought.

I just wanted to take it a small step further by implementing a momentary "ON" that alternates between the two coils w/ every press of the stomp switch (clock) and releases the power going to each coil after release of the stomp switch or momentary turns on then turns off..  My thinking that this should improve battery life somewhat since the coils are not energized all the time.

I actually enjoy doing the research, I'm pretty sure there's a way to do this either w/ N/AND or inverters.  Just thought that someone may have a quick and dirty schematic so I can actually start doing the fun stuff of building the prototype rather than spending the extra time researching.   

Anyway I'll keep y'all posted on the progress!

-bK

[kvb]

oops. tried to help. I goofed.

[R.G.]

I just wanted to take it a small step further by implementing a momentary "ON" that alternates between the two coils w/ every press of the stomp switch (clock) and releases the power going to each coil after release of the stomp switch or momentary turns on then turns off..  My thinking that this should improve battery life somewhat since the coils are not energized all the time.

I actually enjoy doing the research, I'm pretty sure there's a way to do this either w/ N/AND or inverters.  Just thought that someone may have a quick and dirty schematic so I can actually start doing the fun stuff of building the prototype rather than spending the extra time researching.   

Those circuits from the 0.1uF cap to the relay coils are a momentary pulse to the relay coil. It *is* a quick and dirty schematic to do this. Each high-to-low transition on the input to the 0.1uF caps causes a short pulse positive on the base of the transistor, turning on the relay coil for a bit.

The first two inverter sections are a triggered flipflop, the next two do nothing except provide the in/out of phase inversion for flipping one then the other relay coil.

There are possibly dirtier circuits, but one $0.25 IC and a couple of transistors can't be all bad. 

[tranceracer]

First of all a huge thank you RG for all your assistance!
Finally had a chance to breadboard this and got it to WORK!  I had to modify the original schematic a little because for some reason the pulses didn't work when the 100K resistor, after the .1uF cap, was connected to V+.  After playing around with the circuit I changed the the 100K's connection from V+ to V- and *WHOA!* the circuit alternately pulsed to the separate relay coils!   EXACTLY WHAT I NEEDED it to do!! 

I modified the layout a little to get the inverter count to 4 and it seems to be working fine.  Chip is running very cool to the touch.  Can anyone see major potential issues with the revised circuit layout using 5V relays?

It seems that the latching transistor is not needed, because I placed an LED after the inverters that connect to each coil to observe the pulses and each coil engages on what looks to be approx 10ms pulses.

Here's the diagram:


Again thanks RG!  Like I said I bought 25 of these and at about $3.25 each, you saved my a HUGE amount of $$, but more importantly, this is another option for a lower power relay driver for those who are using relays in their circuits!   

-bK

[trixdropd]

So this circuit has had no issues?  I don't know what kinda cmos chip to buy. Anyone got a link or a name?

[R.G.]

So this circuit has had no issues?  I don't know what kinda cmos chip to buy. Anyone got a link or a name?

CD4049. This one has a lot of output current drive, accounting for its being able to drive the (presumably sensitive coil) relays directly.

The CD4069, 74C04 have lower output drives.

[trixdropd]

So this circuit has had no issues?  I don't know what kinda cmos chip to buy. Anyone got a link or a name?

CD4049. This one has a lot of output current drive, accounting for its being able to drive the (presumably sensitive coil) relays directly.

The CD4069, 74C04 have lower output drives.

Thank you R.G..

I did A ton of reading on your  programmable footswitch (from the ampage archive in 2000) and I may be giving it a go in the near future.