ok, running into some problems. Since I couldn't get the dual 555 to work with your diagram, I decided to go to a very basic circuit just to see if I could pulse an LED. Here are the components:

disch -----POT vari resistor---- thres
disch --- 10k res ---vcc+12v
contr v --- .01 uf----gnd
reset-----vcc+12v
gnd --- gnd
output --- 560 ohm res ---- LED ---- gnd
thres --- jumper --- trig
trig --- 100uf --- gnd

I can pulse LED fine and control it with the POT for a 50/50 duty cycle, but when I try to add a connection from output to a 12v relay, (output---relay----gnd) the relay will close on the pulse but when its time to let go it chatters for a half second or so before it releases. I tried putting a diode 1N914 in series with the input lead of the relay to prevent any disconnect feedback but that didn't help..??

 

Should be a bit more substantial than a 1N914, something of at least 1A current like a 1N400x series and it goes in parallel with the coil, cathode end to the positive end of the relay coil.

 

ok, got a beefed up diode and that took care of the problem, now I'll go tinker and try to get the more complex version to work. thanks

 

OK, got side tracked for a few months, but now back on it. I decided to build a simplified circuit first just to verify the basic operation. I have used two separate 555 timers and instead of the switches I just limited both timers to one single capacitor and resistor path. I also adjusted the values down so that I could see the action in seconds rather than in minutes or hours. I think I have it working to a degree but one major thing that I did was to connect R5 to +12v rather than to ground. Is that what you intended or do I have something really messed up? When I do it this way I can get a pulse off of timer 1 every 10 seconds or so, and then on the trailing edge of the pulse I get timer 2 to pulse for about 2 seconds (all controlled by my cap/res values)..