Simple Pneumatic Timer Circuit

The article explains a simple two step IC 555 timer circuit which can be used for sequentially operating any specified industrial mechanism system, in this application it's used for operating a pressurized pneumatic ball throwing arm. The idea was requested by Mr. Ray Strong.

Technical Specifications

So glad I found this site, might be my new Favorite. I'm an amateur here who's racked his brain enough already.

Hoping you can help me out. What I need is an "on delay/true off delay timer" as detailed here--> https://drive.google.com/open?id=0B8cU3NynJy7kekE4bXIxUFBORXM .

The signal going to the delay timer will be from a "pulsepause timer" and I would like to just have the delay timer delay that pulsepause signal before replicating it a half second later to another component.

Basically I need it to produce the same signal for the same duration but just delayed a fraction of a second.

Is there something cheap out there that will do this for under $30 or could you provide me with a schematic.

I plan on using the supply voltage to supply the three things that would need it (pulse/pause input,pulse/pause relay input and the delay timer relay input).

I suppose this could all be incorporated on one circuit board but I already have the pulse/pause timer and am just looking to add a second delayed signal.

But to add to that I would like the "T2" delay (shown in the above posted link) to be adjustable from about .1 to 1 second.

What I am using it for is a pneumatic ball throwing arm. The pulse/pause timer output will be used to trigger a latch to hold/lock the arm and also to trigger the start of the delay timer at the same time.

At the end of the "on" delay of the delay timer it will trigger the pneumatic valve to open, pressurizing the cylinder (which is still held by the latch).

At the end of the pulse/pause time (when pulse pause relay is opened), the latch will release allowing the cylinder to extend at a higher rate than would be possible without it being previously pressurized. Now the next part is where I want it adjustable.

I need the time the relay on the delay timer is is closed to be adjustable so I can adjust how long the pneumatic valve is opened. Another spec would be that the "on" delay of the delay timer should be about .25 to .5 seconds.

Sorry if this is confusing. I'll post a sketch today to give you a visual.

Thanks!

Here's the sketch:

The Design

The proposed two step timer for operating a pressurized pneumatic arm can be studied through the following circuit design.

The circuit is designed such that it includes both the timer stages (t1 and t2) together, and the external pause/pulse mechanism can be eliminated.

Basically two IC 555 stages are used here which are coupled together in series, both of these are configured as monostable operators.

When power is switched ON, the pin#3 of the left IC is held at a low logic which triggers pin#2 of the right hand side IC to ground, however pin#3 of the right side IC is unable to go high and respond to this trigger because its pin#4 simultaneously goes through a momentary disabling (resetting) via the 100k and the 0.33uF capacitor.

Thus in the meantime its pin#2 capacitor 0.22uF charges  and keeps things frozen for the moment with no reaction on the connected relay.

SW1 forms the trigger initiator, as soon as SW1 is pushed, pin#2 of the left IC receives a ground signal and pulls pin#3 of the IC high, activating relay#1....the solenoid stopper now gets energized through this relay.

The above action allows the right side IC pin#2 capacitor to get discharged via the two 10K resistors across its ends and allows this IC to attain a standby position.

The left side IC now counts depending upon the setting of its 1M preset and the 1uF/25V capacitor.

Once the time elapses, pin#3 of the left IC reverts to logic zero, causing a momentary negative pulse to pin#2 of the right side IC. Relay#1 deactivates, de-energizing the stopper solenoid connected to it.

This prompts a sequential toggling of the right side relay whose pin#3 now becomes high and which in turn switches ON the connected relay#2. The solenoid valve instantly get energized at this instance via relay#2.

The IC now begins counting the delay period as set by the RC components across its pin#6/2.

Once the timing of the right side IC too elapses, its pin#3 goes low deactivating relay#2, and resetting the timers to its original condition.

The diode linking the two ICs makes sure that while the right IC is counting, any triggering of SW1 only helps to prolong the counting of the IC due to the resetting (discharging) of its timing capacitor at pin6/2.

Feedback from Mr. Ray Strong

Thank you so much for your help and prompt response, however in reading your explanation of the timer circuit for pneumatics I'm not sure that it operates to the specs I need.

You mentioned that the external pulse/pause timer can be eliminated but that is the circuit that will be triggering the cycle every 8-10 seconds. As I mentioned you could incorporate that timed trigger into the the delay circuit but I don't see that you did that here. Y

ou mention when SW1 is pressed that relay #1 is activated and the solenoid stopper gets energized. That's fine but for my purposes I would have the voltage from pulse/pause circuit be the trigger in place of your SW1. Basically I need to have the whole thing cycling every 8-10 seconds to throw a pitch every 8-10 seconds. So a push button isn't the best for me. For my sake I'd prefer to use the external pulse/pause timer for now as I can use its output to control other components of my mechanism.

Also you mention from my understanding that when the stopper solenoid is de-energized the valve is then energized.

This is not what I was expecting. What I needed was for the valve to energize for about .5 seconds before the stopper de-energizes and then stay energized for an adjustable time period after the stopper de energizes. Basically I need what my sketch illustrates.

Forgive me if these specs have been met in your design, but I didn't understand how your explanation of the circuit met my needs. Could you possibly have a second look to see that these timing needs are met and if possible could you list the steps also with a more straight forward explanation, like just the steps the cycle would go through.

Here is a better laid out description.

If you have any question before you get into the design feel free to let me know.

As per the above discussion I have made the appropriate changes in the design, the finalized layout may be witnessed below, and understood with the adjoining explanation:

Positive supply is applied to the pin#16 rail of the IC 4017, when switched ON, C4 resets the IC causing pin#2 to produce a zero logic at the base of T3, and the entire circuit waits in a standby condition.

When a positive pulse is applied to the base of T2 from the external pulse/pause timer, T3 instantly conducts and actuates RL1 switching ON the "stopper solenoid".

In the meantime C1/P1 along with T1/T2 which forms a short delay ON timer circuit (t1) also responds to the external trigger and latches via R8/D6 and in the process activates RL2 after some delay as determined by the setting of P1/C1.

RL2 now actuates the pneumatic valve.

After a predetermined delay, the pause pulse timer switches OFF, turning OFF T3 and RL1 along with the stopper solenoid.

As soon as T3 switches OFF, pin14 of the IC4017 receives a positive trigger pulse via the relay coil and R3.

The above trigger forces a sequential high logic to jump from pin#3 (not shown) to pin#2 of the IC.

Another "delay ON timer" (t2) connected across pin#2 of the IC now begins counting, and after some delay T4 is switched ON, along with T5.

T4 sends a resetting pulse to pin#15 of the IC, while T5 conducts and makes sure that the T1/T2 latch breaks so that RL2 is deactivated along with the valve solenoid.

The above actions completely resets the entire circuit until the next input from the pulse/pause timer is applied.

About the Author

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials. If you have any circuit related query, you may interact through comments, I'll be most happy to help!