Came up with what I think is a minimum component dual timer.
Integrated trigger and time delay off.
It's a solution for/from another thread.

As I just woke up and drew it out before I forgot, I'm wondering if someone would check for errors?

Low pulses trigger after reaching duty cycle set by R3-C3.
Minimum time on set by R2-C2.
Input low = always on.

D1 keeps C2 low and ready for full delay off cycle.

I don't know if this is unique or I've reinvented the wheel, but it seems to do what I need.

 

Just adding some labels.
A bit scatter-brained right now. Can't seem to cerebrate.

 

Thanks for looking.
Wish I could do that!

The schematic sw I use didn't even have a 555. I had to build it.

I see one problem already. The 1MEG will need to be a little larger to let pin 2 get down to 1/3 of supply and trigger reliably. (your helpful label reminded me)

This is for a tank level indicator.
http://forum.allaboutcircuits.com/showthread.php?t=94220
I can't believe on/off timers are so hard to find.

edit:
Don't bother with the math.
Times are immaterial.
Just basic function is fine,

 

Thanks for looking. Wish I could do that!

What? Add labels or cerebrate?

 

When power is applied, C3 immediately raises trigger above 1/3 Vcc and that sets the output low (no LED).
When power is applied, pin 6 is low and waiting while R2 starts charging C2 towards 2/3 Vcc, therefore output is high.

Illegal condition. Results undefined, and I haven't even gotten to the switch. We need somebody to simulate this to see if I'm wrong.

 

When power is applied, (switch open)C3 immediately raises trigger above 1/3 Vcc and that sets the output low (no LED).(yes)
When power is applied,(switch open)pin 6 is low and waiting (yes)while R2 starts charging C2 towards 2/3 Vcc,(can't charge with disch. pin low) therefore output is high.(no)

Illegal condition. Results undefined, and I haven't even gotten to the switch. We need somebody to simulate this to see if I'm wrong.

Yeah, I'm hoping for simulation.

I believe there are 555 gurus on here. If it works, I'd like to no if it's unique. (in a good way)

If it doesn't work, someone can point me to a minimum timer, that does delay on AND delay off, from a low side switch.

This is the only way I can build circuits. Waking up with an inspiration. I never learned how to learn from others.

I may get time to build it tomorrow.
Haven't worked with 555s for years, but still have parts. Maybe even a board that I can solder up.

Thanks again.

 

Slow on and slow off seems like it can be done with a cmos Comparator or op-amp and an RC, which, after all, is what a TL555 is, but containing a bunch of decision makers.
12V, resistor, SPDT switch, capacitor, Schmitt trigger, viola. Am I missing something?

 

As you say, that's what a 555 timer is.

If someone comes up with a <8 component dual delay with other components, I'll check it out. (not counting switch or indicator)

I started with discrete components. Then thought, why? By the time you get trigger levels, latch, and hysteresis.

 

The circuit works after a fashion.

Close S1 and hold it closed. After 4 seconds pin 3 goes high. Open S1 and after 4 seconds, pin 3 goes low.

Simply closing S1 and releasing it before pin 3 goes high does nothing. Likewise, holding S1 closed keeps pin 3 high for the duration of the time S1 is closed plus 4 seconds.

I suppose there is a use for the circuit, but it seems more likely to require a toggle switch for S1 than a momentary push button.

 

I'm just too busy to really pay attention lately. Go to Off Topic and see my Lucky Day thread. I hope you have something to add to that thread.

 

Can't seem to cerebrate.

Cerebrate, cerebrate. Dance to the music.

 

The circuit works after a fashion.

Close S1 and hold it closed. After 4 seconds pin 3 goes high. Open S1 and after 4 seconds, pin 3 goes low.

Simply closing S1 and releasing it before pin 3 goes high does nothing. Likewise, holding S1 closed keeps pin 3 high for the duration of the time S1 is closed plus 4 seconds.

I suppose there is a use for the circuit, but it seems more likely to require a toggle switch for S1 than a momentary push button.

Hope to get it built later.
The push button will be a level sensor that is either on, off, or bouncing.
From what you say it will work just as wanted.

It will ignore some bounces-on and some bounces off.

 

If someone comes up with a <8 component dual delay with other components, I'll check it out. (not counting switch or indicator)

Don't tell #12, but I can do it with a 50 cent micro-controller and a .1uF cap (not including the switch and indicator.)

 

Put it together last night and it works as I had hoped.