A sink that opens when told to and closes automatically after a customizable amount of time.

Thread Starter

Mr IC Socket

Joined Jan 7, 2020
4
I have been asigned a project for wich i have to desing a circuit that includes:
-A START button
-A STOP button
-A +(or up) button
-A - (or down) button
-Two 7-segment displays
-An electronic valve
It must do the following:
The user controls the time (in seconds) in wich the sink will be open through the + and - buttons. They add/sustract 1 second respectively. Then, they press the START button and the sink should open for the time previously indicated. If the user desires to close the sink before the time is up, they should press the STOP button. In doing so, they also reset the timer. If the user presses the START button without giving an amount of time, the timer will count 15 seconds by default.

I was thinking i could get a 27VDC solenoid valve, since it is easier for me to work with "low" voltage

The things that are giving me a hard time are:
-making the clock, as well as making the exeptions for the clock (example: Stop button, Start button default time). I have been looking up schematics and experimenting on my own, but i can´t seem to find a way to make it without it taking a lot of space in the PCB (although that could be due to poor PCB desing on my part).

I´ve managed to make an ascending clock (Pic attached), but not much else.

Note:
-All of it must be done without any coding
-The software i use for making my desings is Altium Designer 2018
-The software(s) i use for simulation are Livewire and Circuit Wizard.

Thank you for reading and any help you could offer would be greatly appreciated.
I apologize for any grammar error or bad posting practices, i am new here and English isn´t my first language
 

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ericgibbs

Joined Jan 29, 2010
13,668
hi,
The problem with the 4033, it only counts UP.
How do you plan to allow the user to enter the required Time value.?
I know that the UP count can be entered as a UP count by a using a Push button, But what happens when the START timing switch is set to Run.??

E
 

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pmd34

Joined Feb 22, 2014
520
You say you are not allowed coding so no microcontrollers (?)... but are you allowed to use a Programable Logic Deivce? This would make your life much easier, you could build up the full logic "schematic" in the design software (similar to the schematic you have already) but and then just use one IC, this could do the time keeping, display driving etc.. Im used to using Altera MAXII and the free quartus software for such things, but there are a couple of other options, "lattice" and also Xilinx.

27V is actually a bit strange, 24VDC is the more normal. The easiest way of actuating such a solenoid would be with an N-Channel mosfet (with a diode across the solenoid coil to prevent back EMF).
 

Thread Starter

Mr IC Socket

Joined Jan 7, 2020
4
You say you are not allowed coding so no microcontrollers (?)... but are you allowed to use a Programable Logic Deivce? This would make your life much easier, you could build up the full logic "schematic" in the design software (similar to the schematic you have already) but and then just use one IC, this could do the time keeping, display driving etc.. Im used to using Altera MAXII and the free quartus software for such things, but there are a couple of other options, "lattice" and also Xilinx.

27V is actually a bit strange, 24VDC is the more normal. The easiest way of actuating such a solenoid would be with an N-Channel mosfet (with a diode across the solenoid coil to prevent back EMF).
Quite frankly, i'd love to use a Programable Logic Device, but i have little to no knowledge on that area. I can do a few things with C#, but that's as close as i am to coding an IC. However, i know a few people who might be able to help me with that, since they work with PLDs all the time.

Regarding the voltage of the valve, it doesn't really matter as long as it's around 20V-30V. I´ll see what the local store can offer
 

Thread Starter

Mr IC Socket

Joined Jan 7, 2020
4
hi,
The problem with the 4033, it only counts UP.
How do you plan to allow the user to enter the required Time value.?
I know that the UP count can be entered as a UP count by a using a Push button, But what happens when the START timing switch is set to Run.??

E
The schematic is mostly me figuring out timers in general, so it probably won´t be a part of the final project. Do you know any ICs that count Down?
 

pmd34

Joined Feb 22, 2014
520
The 74HC4510 is an up down counter that would do the job I guess.
The CPLD stuff is actually OK, I wanted to make a high speed counter so I had to learn it myself. There is actually no programming in it, you basically sketch up a logic circuit schematic, and then "compile" it and program your chip.. job done, the chips are pretty cheap and you can get a Chinese copy programmer for about $30. There is a free version of the software which so far I have not actually found the limit of!

There is a lot of stuff on the net and youtube to show you how to do it but this one gives you an idea:
(I would turn the sound off though!!!)
 

ericgibbs

Joined Jan 29, 2010
13,668
hi MrIC,
Have you prepared a Flow Chart of the project, it will help you create the circuit.
Post the chart if you have already have copy.
E
 
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