Hello all,
I am brand new at all of this. I thought someone on here may have an idea. I am just staring to learn about all these things. I am looking for some help. I am a farmer and I need to build or buy something that runs off of 12 volts. I have a pump that cannot run dry when transferring fertilizer from one tank to another. When running the machine there is a multitude of electronics that are being monitored when planting crops. Sometimes turning the pump off when one tank is try tends to get forgotten. I would like to put a timer in-line that activates when the switch is turned on and resets when the switch is turned off. I want it to run a pump for 5 or 10 minutes and then shut it off. The pump does pull high amps. I do have a relay in-line to deal with that. Can anyone please direct me where to get what I’m looking for or help with getting the parts needed to do so?
A push button, a 555 with the appropriate sized timing cap/resistor, transistor to drive the relay... that should do.
Or if you want to go the (more flexible) Arduino route: an Arduino, push button, transistor to drive the relay.
Thanks for your response.
I believe going the “more flexible route” is kind of what I’m looking for. That can be built pretty easily? Like easily enough for a new guy with no arduino experience?
I’m not going into this completely blind, I do work in 12volt systems but it’s basic stuff.
Very easy.
Transistor on the output of the Arduino to switch the relay; button on a separate input.
Code can be as simple as:
const uint8_t buttonPin = 5;
const uint8_t relayPin = 6;
void setup() {
pinMode (buttonPin, INPUT_PULLUP);
pinMode(relayPin, OUTPUT);
}
void loop() {
if (digitalRead(buttonPin) == LOW) {
digitalWrite(relayPin, HIGH);
delay(5*60*1000ul);
digitalWrite(relayPin, LOW);
}
}
Note: using delay() ensures the Arduino can't do anything else...
Neither budget nor time frame nor expansion need was stated but, there are also 'smart relays' out there for just this sort of thing. Like anything else there's a range of capabilities and prices.
IMO an advantage is that a lot of the tedium is already handled. If you'd choose a 12VDC item the level translation issue is gone. They come with screw terminals in place. DIN rail mounting, usually. Would be more rugged than your arduino board. Instead of designing a control almost from scratch ( don't discount the Arduino learning curve ) it's basically hook up the wiring and load the program - some may be key-in only.
https://www.factorymation.com/SG2_PLR_Smart_Relay/Full-feature_PLR_SB
YMMV
A common "ON delay" relay would probably work, but would need to see a schematic of your apparatus.
Thank you for the responses!
Before buying parts, get the design down tight. You can save loads of time with good hard upfront planning.
I for one would have tank level sensors as well as time limiting the pump. I'd have indicator led(s) near the controls too.
Switching 12VDC ON/OFF, how many Amps does the pump draw? There's likely a power FET that can do it for less than $1.
If you have chickens, coop door automation is a project that comes by every year or two.
One small, cheap Arduino board can control dozens of things when done right.
GoForSmoke:
Before buying parts, get the design down tight. You can save loads of time with good hard upfront planning.I for one would have tank level sensors as well as time limiting the pump. I'd have indicator led(s) near the controls too.
Switching 12VDC ON/OFF, how many Amps does the pump draw? There's likely a power FET that can do it for less than $1.
If you have chickens, coop door automation is a project that comes by every year or two.
One small, cheap Arduino board can control dozens of things when done right.
Excuse me if I don't use the correct terminology. My current set up has a switch in the cab that runs a relay. The pump I had only put out about 7 gpm, but pulled about 20 amps. I have installed a different pump that is 20 gpm. I cannot find a chart telling about amp draw. The pump is a long way from the switch so I used the relay. I was thinking about switching to a solenoid. I believe the new pump will draw fewer amps. I want to be able to push a button or flip a switch and the pump runs for a set amount of time like 5 or 10 minutes. It's just transferring liquid from a front tank to a bigger tank pulled on a planter. A push-button is fine. From what I am reading I can do this with a UNO? Also looking at the other posts it looks like this already exists. I need to make something simple and reliable. It cannot be something that has to be reset every day or time. One of our older operators already has enough trouble with the technology in the cab and we are upgrading to a more complex planter. I need to keep it simple.
An Uno can do it. It's overkill but it can. A Nano is cheaper and smaller, has the same chip in a smaller form and can do it.
A power FET like IRLZ44N can switch that 12 pump ON and OFF with as little as 3V on the gate. It needs a heatsink (screw the tab to thick steel that doesn't get hot) and maxes out at 47 Amps if kept 25C/77F and down to 33 Amps at 110C/212F whether 5V, 12V or 50V.
"The pump is a long way from the switch so I used the relay."
So? Using a FET is like a using relay only easier and uses far less energy and the relay is more expensive and likely to wear out sooner. The T in FET is for transistor. FETs are very efficient when full open or closed.
The relay can switch AC, the FET can't. What you want to run off mains power cheaply, get a big enough relay.
With tank level sensing the pump won't run 10 minutes when there's 5 minutes of stuff to pump, including if a hole gets knocked through the tank and you don't see it drain... the operator doesn't need to do anything but notice a blinking red light and realize something needs checking. What can I say, I don't just plan for everything to always go right. Life taught me different, "things happen".
With tank level sensing you might make it so the operator doesn't have to touch a switch for the pump to run. The tank reaches a high level and the pump runs till the level is low --- like how thermostats work.
If you don't want extras then you don't need Arduino. Even with tank level sensors you don't, you wouldn't even need a timer FWIW.
Thanks for the info!
While 2 floats would do fine running a sump pump I started thinking about a tank that could be shifting, rocking, wavy and how floats would do that and come to the conclusion it'd be cheaper with 1 little tube float at the tank bottom and yes, a microcontroller timing state changes of a tilt switch inside. When it stays OFF, the tank level is below the float top.
If your 5 or 10 minute pump time could empty the tank, you might want to add a level switch with your timer. Both would have to be ON for the pump to run. The same controller would run both.
Experiment with the current draw difference of the pump between normal and dry condition.
Monitor this level and switch off the pump when this latter condition lasts for say 2 seconds.
There are sensor modules out there for a few dollars quite capable of monitoring up to around 200A which easily interface with Arduino.