I am trying to create a device that dispenses water. I want the device to be as cheap as possible, while still being able to dispense a specific volume of water. The amount it dispenses should be based on time if I use a 555 timer. I thought I could run a relay off of the timer so it could run the water pump for the amount of time you set with a potentiometer. To add a more adjustable time range, I thought I could add a switch to make the path travel through another resistor, along with the potentiometer. I don't have any experience with circuits and how the components interact. I would like to know if this design could possibly work, what I would need to do to it, or if I'm even on the right track. I also don't have a power supply or design with it. I was also thinking of having the power supply built into the board, so there wouldn't have to be a wall wart. All I need is a proper schematic, so I could test it out on a breadboard and have the board manufactured. I will be 3D printing a case for it. If there is any more information you need, please ask. Thank you.

 

Circuit schematics is the language of electronics. This is how we communicate clearly the design of a circuit.
I have no idea what your circuit represents.

This is one example of how one would draw a circuit schematic involving a 555-timer IC.

 

Circuit schematics is the language of electronics. This is how we communicate clearly the design of a circuit.
I have no idea what your circuit represents.

This is one example of how one would draw a circuit schematic involving a 555-timer IC.

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Maybe tagging this with circuit analysis was a mistake. I do not yet know all of the models of the components, nor do I have any completed schematics. I am not fully aware of how circuits work and would like to know if, as a concept, this device could possibly work with any combination of models in the arrangement in my diagram above. I am really looking for a circuit design that could do what I've stated I want it to do, whether or not it is my design, but I thought that this design that I came up with, with my limited electronics knowledge, could possibly work. My hope is that someone will at least tell me if I'm on the right track.

 

If you are new to electronics principles and design techniques now is a good time to begin with something simple.
For drawing schematic diagrams, I would suggest that you get a circuit simulator or a schematic drawing program.

Check out Scheme-it from Digikey.
https://www.digikey.com/en/schemeit

All components are given a reference designator letter and number such as D1, U3, R2, C8, etc., and a component value.
You do not use arrows and labels such as "NPN transistor", "regulator", "manual switch". These are implicit to the informed reader.

Start learning by building a simple circuit such as a flashing LED on a breadboard. There are many websites that will introduce you to the 555-timer IC.

https://www.instructables.com/LED-Flashing-Project-Using-555-Timer-IC-a-Step-by-/

http://www.learningaboutelectronics.com/Articles/LED-flasher-circuit.php

 

Really, the electrical circuit drawing was very good for a beginner. ( The drawing, not the circuit)
The circuit may not function as desired. The circuit does seem rather complex for the functions described, though. Probably neither the relay nor the pump will require a regulated voltage for operation.

 

I see numerous problems with the circuit as drawn and yes, it's hard to read.

Another problem you may or may not face going about things this way. I tried a similar concept decades ago and timing really is not a good way to go. Timing assumes the water line pressure to be a constant. My pressure kept changing, a toilet flush, wife running washing machine and the list goes on. You are using the 555 timer in a monostable configuration, also called a one shot. A Google of 555 timer one shot will yield plenty of results. Also a Google of "555 one shot module" will bring up a few dozen inexpensive complete modules. Either way I would include a pot (variable resistor) in my scheme so the actual final time On of the output pulse can be adjusted. You want that flexibility in your design. So if a timing function will work for you by all means try it. Also, keep in mind the cheap Chinese module boards which include a relay that the relay contacts are only good for about 1/2 the advertised current. If advertised for 220 VAC 10 Amps figure the contacts in reality will handle a 5.0 amp load.

Ron

 

The datasheet for the old NE555 shows that its minimum power supply is 5V where it barely works. It shows that its output goes as high as the supply MINUS 1.4V (+3.6V in your circuit). The 3.6V feeds the base of the emitter-follower transistor resulting in the relay coil getting only 2.9V.

The relay coil probably does not activate with only 2.9V but if it did then the relay feeds 12V to DESTROY the base-emitter of the "trigger" transistor.

 

There are a few timer-solenoid circuits available, and a caution that timed water delivery is a variable. In industrial systems timed delivery is used with closely regulated pressure, to assure a constant volume delivered. Also in vending machines.