Hi
I have read a lot about the 555 timer and the different modes that it offers. Of course, my needs are just a bit different. I am looking for suggestions on how to design my circuit. I have been thinking that a 555 is the way to go but now I am unsure. This is what I want my circuit to do once it is activated :

1. Perform a delayed start of about 10 seconds
2. Energize a relay that will change the led that is on for my stop light from red to green
3. Reset itself to wait for another activation and do it all over again but change the stoplight from green to red.

My scenario is a 12 volt model train that is activating existing IR sensors which in turn would activate the delayed start sequence above. My circuit will be powered by 12 v dc.
Thank you in advance for any suggestions. Dave

 

What determines whether the stop light goes from red to green or green to red?
Do you need a circuit to also do that?

 

The relay will change the stop light from green to red and Vice versa. The stoplight sequence will always be the same: g-r-g-r and so on.

 

The relay will change the stop light from green to red and Vice versa.

Okay.
I think you need more than just a 555 timer to do that.

Please show the exact sequence and time of all the events that change the signal from green to red (relay on?), and then from red to green (relay off?)

How much current does the relay coil require from the 12V supply?
What is the voltage and polarity of the signal from the IR sensor when triggered?

 

Thanks for your reply. I have attached a drawing that attempts to better define what I am looking for. I no longer think I need a relay. Instead I think I can use an existing electrical component that has SPST relays that are actuated by the IR sensors. These components are already installed. I think I need an on-delay timer that can go for about 10 seconds, energize my new signals and then reset itself. I hope that my attached drawing will better explain my problem and what I am looking for. Thank you so much for your help. Dave

 

Hi
I have read a lot about the 555 timer and the different modes that it offers. Of course, my needs are just a bit different. I am looking for suggestions on how to design my circuit. I have been thinking that a 555 is the way to go but now I am unsure. This is what I want my circuit to do once it is activated :

1. Perform a delayed start of about 10 seconds
2. Energize a relay that will change the led that is on for my stop light from red to green
3. Reset itself to wait for another activation and do it all over again but change the stoplight from green to red.

My scenario is a 12 volt model train that is activating existing IR sensors which in turn would activate the delayed start sequence above. My circuit will be powered by 12 v dc.
Thank you in advance for any suggestions. Dave

You can use a 555 in monostable mode+ a CD4013 toggle flip-flop.

 

I'm having difficulty reading your notes as they are rather faint.
Can you post them here?

 

I think I need an on-delay timer that can go for about 10 seconds, energize my new signals and then reset itself.

Having trouble following the logic in the attachment for #5.
If S1 is GREEN then S2 must be RED. Where exactly does the CCW train enter the loop and wouldn't S2 stop the train before it ever gets to Sensor 2 and 1?

 

Having trouble following the logic in the attachment for #5.
If S1 is GREEN then S2 must be RED. Where exactly does the CCW train enter the loop and wouldn't S2 stop the train before it ever gets to Sensor 2 and 1?

The train enters the loop at the switch (see diagram). The signals only face east (see compass rose on diagram). Therefore, a ccw train is not affected by signal 2. I will post a clearer diagram soon. Thank you.

 

I'm having difficulty reading your notes as they are rather faint.
Can you post them here?

Here is a clearer copy. My apologies.

 

Sorry, still rather illegible.
If you can't post those statements here as a typed post, I can't help you.

 

Below are the notes from my attachment. I apologize for the confusion and thank you again for your help.
1. Signals face east. This means that only trains exiting the loop see them.
2. Signals powered by 12v dc.
3. Train movement through the reversing loop alternates between cw and ccw. There is only 1 train in the loop at a time.
4. As a train exits the reversing loop the sensor will change both signals for the next arriving train which will be going in the opposite direction. This is where I think I need a timer since the sensor is before the signal. For instance, an exiting ccw train crosses sensor 1 which turns the green signal 1 red before he passes signal 1. The train needs a green signal 1 to exit. The loop exit is at the switch. Hence, an on-delay timer is needed to keep signal 1 green so the ccw train may exit.
5. I have incorporated most of this into item 4, above. I need the timer to be about 10 seconds long for a train to activate a sensor and then pass the signal. Sensors are only activated by exiting trains. For instance, sensor 2 is not affected by a ccw train entering the loop.
6. Signals 1&2 are always opposite: r-g, g-r, never g-g or r-r.
I hope this is more clear. Thank you again for your help.

 

Does the sensor when activated by a train stay on longer then 10 seconds?

 

Still all a little fuzzy.
Could you do sort of a time-line of events such as below:
Just tell us the sequence of what you want to happen, not what you think you need.

1. Train enters CW
2. Train trips CW sensor
3. After ? seconds, signals changes from green to red
4. Signal changes back from red to green after???
5. Etc.

 

I need the timer to be about 10 seconds long for a train to activate a sensor and then pass the signal.

First try if I have this figured correctly.
When first powered up the Green LED1 on Signal 1 is ON.
When the train activates Sensor 1, power is applied to the 555 timer and a 10 second delay determined by C2 and R1 begins.
At the end of the 10 seconds the output of the 555 goes High and triggers flip flop IC2 turning ON the Red LED2.
Sometime after the train has passed Sensor 1 I'm assuming it shuts OFF which will reset IC1.
Mosfets M1 and M2 are the drivers for the LEDs. R2 and R3 values dependent on the LED type.
The other half of IC2 can be used for the Signal 2 circuit.

 

Below are the notes from my attachment. I apologize for the confusion and thank you again for your help.
1. Signals face east. This means that only trains exiting the loop see them.
2. Signals powered by 12v dc.
3. Train movement through the reversing loop alternates between cw and ccw. There is only 1 train in the loop at a time.
4. As a train exits the reversing loop the sensor will change both signals for the next arriving train which will be going in the opposite direction. This is where I think I need a timer since the sensor is before the signal. For instance, an exiting ccw train crosses sensor 1 which turns the green signal 1 red before he passes signal 1. The train needs a green signal 1 to exit. The loop exit is at the switch. Hence, an on-delay timer is needed to keep signal 1 green so the ccw train may exit.
5. I have incorporated most of this into item 4, above. I need the timer to be about 10 seconds long for a train to activate a sensor and then pass the signal. Sensors are only activated by exiting trains. For instance, sensor 2 is not affected by a ccw train entering the loop.
6. Signals 1&2 are always opposite: r-g, g-r, never g-g or r-r.
I hope this is more clear. Thank you again for your help.

Hi

How is it known whether the train is exiting or entering the loop?

 

Does the sensor when activated by a train stay on longer then 10 seconds?

No, I don't believe the IR sensor stays in longer than 10 seconds when activated by the train. The sensor sends a signal to the electrical component it is attached to and throws the switch so the train can exit without derailing and flips the polarity of the loop (which is insulated from the main line). The sensor will ultimately change the signal lights. I just want a ~10 second delay from when the sensor is actuated so the train can pass the signal as green as opposed to red.

 

No, I don't believe the IR sensor stays in longer than 10 seconds when activated by the train.

Can you verify that?
How long does it take for the full train to pass the sensor?
Do you know how the train activates the sensor, meaning does the train break the IR beam or is it reflected off the train?
Any info on the sensor?

 

Still all a little fuzzy.
Could you do sort of a time-line of events such as below:
Just tell us the sequence of what you want to happen, not what you think you need.

1. Train enters CW
2. Train trips CW sensor
3. After ? seconds, signals changes from green to red
4. Signal changes back from red to green after???
5. Etc.

Sure.

1. A ccw train enters the loop. Signal 1 is already green for the CCW train from the past CW train exiting the loop.
2. The ccw train activates sensor 1 which throws the switch so the train can exit. The sensor also throws the SPST relays I have drawn on my one-line. These SPST relays will control my signals.
3. Signal 1 stays green for ~ 10 seconds an then changes to red. Signal 2 stays red for about 10 seconds and then turns green.
4. The next train comes along and enters the loop cw. Start at the top but in reverse:
   1. Signal 2 is already green for the CW train from the past CCW exiting train.
   2. and so on....

 

Can you verify that?
How long does it take for the full train to pass the sensor?
Do you know how the train activates the sensor, meaning does the train break the IR beam or is it reflected off the train?
Any info on the sensor?

I don't know how to verify that - this is getting out of my wheel house. However, I can offer the website where I purchased the sensors and will also upload an image. My IR sensors are in the track - see image. Also, the Home page of this website provides info on the IR sensors which may be able to help: https://www.azatrax.com/index.html