Hello,

I'm looking for assistance. I've been instructed to design a basic circuit that employs 2 off-delay timers, 1 light and 1 switch. The idea is that upon closing the switch a light will be on for a defined period of time. Once that time has elapsed, the light will be off for a defined period of time. The cycle will automatically continue indefinitely provided the switch remains closed.

I've executed this using 2 on-delay timers. I cannot seem to wrap my head around creating a circuit like this with off-delay timers.

Note: The timers are 11 pin solid state.

I appreciate any advise/help with this.

 

What timer exactly?

 

What timer exactly?

Hi,

It's an Omron but basically looks like this and behaves in the same way. There's a start switch between pins 2 and 6 that when shorted, will change the positiion of the time delay contacts immediately (because off delay), but once the button is released, the timer will commence.

 

Does this one switch need to be connected as a Start switch on terminals 2 and 6?

 

Does this one switch need to be connected as a Start switch on terminals 2 and 6?

No. So the one switch powers the circuit.

I'm thinking there may need to be control relays with NO contacts to control the 2-6. I could be wrong but that's what I'm thinking. 2 control relays maybe in total as the are no instantaneous contacts with this sort of timer.

 

No. So the one switch powers the circuit.

Thanks for the info.
Post how you have it working with the ON delay timers please.

 

Thanks for the info.
Post how you have it working with the ON delay timers please.

This is what I have for on delay.
I have 2 on delay timers. 1TDR and 2TDR.
As you can see I also shorted 2-6.

The operation is as follows. Switch closes, 1TDR is is energized via 2TDR1. 1TDR1 and 1TDR2 delay changing positions for 9 seconds. After 9 seconds both 1TDRs change and now 2TDR energizes for 5 seconds. After 5 seconds 2TDR1 opens and the circuit restarts

In summary red light on for 9 seconds and off for 5 seconds. Repeats.

 

OK. So the challenge is to do that using the timers in the D Mode Signal OFF- delay.
Solution requires using both sets of contacts on both timers.

 

OK. So the challenge is to do that using the timers in the D Mode Signal OFF- delay.
Solution requires using both sets of contacts on both timers.

Ok thank you for the tip. I'm going to go back to the drawing board now to see what I can come up with.

Am I correct in saying that a NO contacts from a control relay will be used to actuate between pin 2 and 6 of the TDRs?

 

Ok thank you for the tip. I'm going to go back to the drawing board now to see what I can come up with.

Am I correct in saying that a NO contacts from a control relay will be used to actuate between pin 2 and 6 of the TDRs?

Based on my schematic, I can have the light on for 9 seconds. This is usIng the NO control relay to control the operation of pins 2-6 on the TDRs. However, I cannot seem to figure out how to have the light off for 5 mins before the sequence restarts.

 

In my setup both timers are activated simultaneously when power is applied.

 

In my setup both timers are activated simultaneously when power is applied.

Edit: I said 5 mins in my last post. I meant 5 secs.

I'm still lost. I know this forum isn't here to provide answers and I'm also not asking for the answer. I'm simply at a stale. If I provide what I have, am I able to get feedback or comments to say if I'm on the correct track or if I'm just out to lunch?

 

Correct the feedback works both ways.

 

Correct the feedback works both ways.

Well to start I sincerely appreciate your willingness to help!

Here's what I have.

So to start CR is energized which will close 2-6 on both TDRs. This will change the position of all contacts immediately (as per Off delay theory) and then since contact in series with CR opens, this in turn opening 2-6 on both TDRs, the timer starts the light is on for 9 seconds. I think the above is correct.

Now where the 5 seconds off comes in that I cannot figure out. Because if I put 5 seconds on 2TDR for example, then the light won't be on for 9 seconds.

 

You have added a relay to the equation, is that allowed?
My solution does not require an additional relay.
Also, how will both Timers get activated if pin 2 is not connected to L1?

 

You have added a relay to the equation, is that allowed?
My solution does not require an additional relay.
Also, how will both Timers get activated if pin 2 is not connected to L2?

I have added a control relay because on these Omron timers between pin 2 and 6 is the start. If I short pin 2 directly to L2, then how do I turn off pin 2 in order to trigger the off delay timer? My understanding of using these timers in D mode (off delay) is that once you short pin 2-6, time delayed contacts change immediately. Only once 2-6 is de-energized afterwards, the timer function starts.

 

My understanding of using these timers in D mode (off delay) is that once you short pin 2-6, time delayed contacts change immediately. Only once 2-6 is de-energized afterwards, the timer function starts.

Correct, but only if the timers have power on pins 2 and 10.

If I short pin 2 directly to L2, then how do I turn off pin 2 in order to trigger the off delay timer?

You don't. Hint: Timer2 runs longer then Timer1 for the required OFF time.
Check out how to activate Timers when power is first applied.

 

Correct, but only if the timers have power on pins 2 and 10.

You don't. Hint: Timer2 runs longer then Timer1 for the required OFF time.
Check out how to activate Timers when power is first applied.

Ok let me run with this and see what I come up with.

I appreciate your prompt replies and hint!!

 

OK.
BTW, back in post #15 I meant to say pin2 to L1 not L2.

 

Hint: Think of using NC contacts for Timer activation.