Ok, I require a circuit that will activate on the push of a button, a 12v small solenoid (DC-NC) to allow water to flow to a small pump (12vdc).
I would like the solenoid to open 5 seconds before the pump, them have the pump activate for 5 seconds.
After the pump activates for 5 seconds the solenoid then closes.
I would like the run time of the pump variable from 5 to 10 seconds if possible.
Thanks to everyone in advance.
P.S.-I know nothing about micros, this will have to be just standard components, thanks.

 

One simple compact way would be a small 8 pin micro.
Depends on your present electronics knowledge.

 

Max, Max, max....I know nothing of micros, it will have to be just standard raw components

 

Kim, Kim, Kim ... This is not a free homework service. Show us your solution to the problem and we will advice.

Update; You didn't say what this is for, but based on your profile it probably is not homework.

Also, think about what you are asking and how little information you have given us to work with.

Solenoid and pump currents / datasheets / websites; power source, etc. - ????

And, a timing diagram.

And - will the button always be released before the pump activates?

And - What is the guaranteed minimum time between when a cycle finishes and when the button is pressed again?

ak

 

2 - FETs
1 - CD4093
0 - 555's

- or -

6 - FET's

ak

 

Based on what we know so far, here is a first pass at a solution.

Closing the switch sets the control flipflop. This locks out the switch while the cycle runs, so repeated button presses do not affect the timers. The solenoid activates immediately. R2-C2 are the five-second pump delay. R3-C3-R5 set the pump run time. The run time increases with clockwise rotation. When it ends, U1 pin 11 goes low, turning off the pump. That transition is differentiated by R4-C4, and that pulse resets the control flipflop, deactivating the solenoid.

D1 and D2 provide a low impedance discharge paths for capacitors C2 and C3, to shorten the circuit recovery time.

Update: Schematic C3 fixed.

ak


Click on the schematic for a larger image.

 

Below is the LTspice sim of ak's Post #6 circuit:

I had to increase the value of C2 and C3 to get closer to the desired time delays.
Also had to increase the value of R4 and thus the time of the reset pulse, to allow sufficient time for U1a to discharge C2 through U1a's output resistance, for a reliable reset of the U1a/U1b latch.

These sim result corrections minimizes these problems being a factor when you build the circuit.

The sim shows the pump operate times for U1 pot wiper settings of 0%, 50%, and 100%.

Edit: As noted in my Post #17, the original 4.7µF selected for C2 and C3 by ak for this circuit may be a better value to use.

 

Kim, Kim, Kim ... This is not a free homework service. Show us your solution to the problem and we will advice.

Update; You didn't say what this is for, but based on your profile it probably is not homework.

Also, think about what you are asking and how little information you have given us to work with.

Solenoid and pump currents / datasheets / websites; power source, etc. - ????
I think I said 12v

And, a timing diagram.
What the hell is that???its a pretty simple timing cycle

And - will the button always be released before the pump activates?
Yrs

And - What is the guaranteed minimum time between when a cycle finishes and when the button is pressed again?
I have no idea
ak

Ummmmm...homework, Im 65, and not getting any younger.

 

Below is the LTspice sim of ak's Post #6 circuit:

I had to increase the value of C2 and C3 to get closer to the desired time delays.
Also had to increase the value of R4 and thus the time of the reset pulse, to allow sufficient time for U1a to discharge C2 through U1a's output resistance, for a reliable reset of the U1a/U1b latch.

These sim result corrections minimizes these problems being a factor when you build the circuit.

The sim shows the pump operate times for U1 pot wiper settings of 0%, 50%, and 100%.

View attachment 366144

Thaank you very much for your elegant circuit

 

Based on what we know so far, here is a first pass at a solution.

Closing the switch sets the control flipflop. This locks out the switch while the cycle runs, so repeated button presses do not affect the timers. The solenoid activates immediately. R2-C2 are the five-second pump delay. R3-C3-R5 set the pump run time. The run time increases with clockwise rotation. When it ends, U1 pin 11 goes low, turning off the pump. That transition is differentiated by R4-C4, and that pulse resets the control flipflop, deactivating the solenoid.

D1 and D2 provide a low impedance discharge paths for capacitors C2 and C3, to shorten the circuit recovery time.

ak

View attachment 366139
Click on the schematic for a larger image.

Thank you very much for your elegant circuit

 

Neither solution nor question have I.
Except this: I have solenoids for my sprinkler system. If you think water not under pressure to open the valve you're mistaken. It takes some amount of pressure to open the valve when the solenoid opens. Gravity fed water, unless the stand pipe is dozens of feet high the valve will not open. There's a spring that holds the diaphragm closed. Water pressure present on both sides of the diaphragm plus the spring tension holds the valve closed. It takes so much pressure (I don't know what that is) to open the valve.

When the solenoid opens it releases the pressure on one side, allowing the main water supply to force the diaphragm open. If you're wanting to use water from a rain barrel what you're proposing won't work. I say this because you speak of a pump. If you were on city pressure you wouldn't need a pump.

Is this to scare away critters from your property?

 

Below is the LTspice sim of ak's Post #6 circuit:

Oh LTS-Master, the student is curious. What trip points does your model use for the 4093? My read of the internal schematic is that they are some combination of a percentage of Vdd and a fixed offset. Various app notes that include the one-gate oscillator circuit are not consistent.

ak

 

Ummmmm...homework, Im 65, and not getting any younger.

Yeah, when I saw that in your profile, I updated that post and posted the circuit. Welcome to the gang of geezers.

ak

 

I have solenoids for my sprinkler system. If you think water not under pressure to open the valve you're mistaken.

Irrigation valves are weird. (repaired one just last week.) Industrial flavors are much less complicated and less delicate, with none of that rubber diaphragm borscht: big coil, big spring, slam it open, slam it closed. Examples in the home: washing machine, dishwasher, furnace humidifier.

ak

 

Examples in the home: washing machine, dishwasher, furnace humidifier.

The humidifier I'm familiar with has a float and lever to close a valve. I don't think that would serve the TS purpose. Washing machines and dishwashers, I think they operate on a similar basis but it's been a very very long time since I dinked around with one of those valves.

The TS has yet to answer what the source of water is. I have rain barrels and depend on a siphon to pull water out of the barrels. It's slow but it gets the job done. The wife wants to use that water on her garden, which would require a pump. 12VDC or 120VAC would be necessary and I'd have to store it in the garage as opposed to letting it live outside in the weather. More than anything else I use rain water for the fish pond. City water is loaded with minerals and fish don't care for chlorine either.

Kim Sleep What is the source of water for your project? How many gallons per minute do you want?

 

In trying to imagine what you're doing I just thought you might be running this in a mobile home or a camper. The pump may be all you need, depending on what kind of pump it is. How much pressure do you want?

 

What trip points does your model use for the 4093?

At the 12V supply voltage, the sim trips at 5V and 7V.
That's a little less than the ≈2.7V nominal hysteresis (23%) the data sheet shows, so the real circuit may indeed give times closer to the desired with the 4.7µF values you selected for C2 and C3.

 

Update: Added a power-on reset so the circuit always powers up with the pump not running.

Update: Schematic C3 fixed.

ak

 

Update: Added a power-on reset so the circuit always powers up with the pump not running.

As I noted from my sim, the reset pulse needed to be lengthened to allow time for C2 to discharge through U1A's output resistance.
A value of 50kΩ for R4 should be sufficient, with good margin.

 

As I noted from my sim, the reset pulse needed to be lengthened to allow time for C2 to discharge through U1A's output resistance.

Are you proposing using the R4-C4 reset pulse as an input lockout period? If yes, then, no. A button-press low input at pin 1 will force pin 3 high no matter what the states of the other input and output. Still, wouldn't hurt to increase R4 to 100K. The only reason I had it at 10 K was parts commonality.

A lockout solution for post #18 would be to move R2 and D2 to U1B pin 4, reverse the signal and logic polarities of both timers, move C4 to U1D pin 13, and drive the pump with a p-channel high-side switch. Without more parts, that forces the circuit, solenoid, and pump to have the same positive voltage supply. Maybe a problem, maybe not.

ak