Switches to fill surge bin

[brent f]

Looking for a simple circuit that would activate a relay that would power an electric clutch to run a conveyor to fill a bin. When the bin is full it would stop filling and then restart again when the bin is almost empty to refill again. I am using it in an agriculture project. I would likely use 2 diffuse sensors but open to suggestions . The product in the bin is a dry product. This would be a 12 volt system. Thanks for any advice.

 

[AnalogKid]

What is the relay coil current or power rating?
What are the voltage and current for the clutch?

Generally speaking, you need a set-reset flipflop. This can be a 2-transistor circuit, an IC such as a CD4013 or NE555.

OR, a 2-relay mechanical-latching flipflop. Now the entire circuit is the relay assembly and two switches. Here is an old-style one from P & B that can handle large loads. There are many smaller ones these days.

https://www.newark.com/productimages/large/en_US/16M9033-40.jpg

ak

 

[brent f]

Thanks AnalogKid.
The relay coil would be a typical 150 to 200 ma draw. The electric clutch will draw about 5 amps. Basically looking for a 3 way switch to turn the relay off and on to run the auger electric clutch. The sensor in the bin could be of any type. Of course the principal of this system is when the bottom sensor is exposed the relay will turn on the auger and run till the top sensor is covered to make it stop. Now the auger will stay turned off even when the product drops below the top sensor. It will stay that way until the product is again lower than the bottom sensor. Once it reaches that point auger turns back on. The cycle keeps repeating. I was hoping to modify or use a cheap kit or simple circuit to do this.

 

[Diver300]

You can do that quite simply with the normal start/stop circuit used for motors.

https://engineerfix.com/wp-content/uploads/2021/08/Start-stop-circuit.png

You need a NC (normally closed) contacts on both sensors. That is to say that you need sensors that close their contacts when there is no product around them.

The lower sensor will spend most of the time covered in product, so it will usually be open. The upper sensor will spend most of its time exposed, so it will usually be closed.

In the start/stop circuit, the lower sensor is wired as the start button and the upper sensor is wired as the stop button. When the product drops below the lower sensor, the lower sensor contacts close, starting the auger. When the product gets above the uppers sensor, the upper sensor contacts open, stopping the auger. When the product is between the two sensors, the auger won't start or stop.

If your sensors can handle the full current that the auger motor takes, you can wire the motor in parallel with the relay coil. If not, you either need a two-pole relay, with one pole running the start-stop circuit and one running the auger, or you can have two relays with the coils in parallel. Then the contact of one relay will run the start-stop circuit and the contact of the other will run the auger.

You don't need a latching relay. The circuit will latch for you. The only difference is that without a latching relay, when you turn on the power, and the product is above the lower sensor and below the upper sensor, the auger won't start. If you had a latching relay, that could remember over a power loss whether the auger was running or not before the power loss. I doubt that difference would be important to you.

 

[brent f]

Thank you for the information. I will be using capacitive promximity sensors NC. I still not sure about the relay. Is this a typical automotive type relay? At this point not sure of the wiring of the relay. I will use this relay to activate the coil on another relay as the load will draw about 4 or 5 amps at 12 volts.

 

[Diver300]

Can you send details of the sensors you will be using? Capacitive sensors are often 3 wire ones so the wiring is a little more complicated. I can draw out the circuit if that would help.
You can use standard automotive relays. You will need two single-pole relays. You could use one double-pole relay if you wanted but that wouldn't be a standard automotive one.

 

[brent f]

• Baomain Capacitance Proximity Sensor Switch LJC30A3-10-Z/AY DC 10-30V 200mA Detector 10mm PNP NC 3-wire​

  • Output Type : PNP NC(Normal Closed);
  • Diameter of Head : 30mm;
  • Detecting Distance : 10mm
  • Wire Type : DC 3 Wire (Brown, Black, Blue);
  • Switch Appearance Type : Cylinder Type
  • Supply Voltage : DC 10-30V;
  • Current Output : 200mA;
  • 
    

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    I was thinking of using these sensors as recommended being Normal Close and will be a 12 volt system. I would greatly appreciate your offer to draw out wiring diagram.
    
  
  
  
  
  

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[Diver300]

This is the circuit that should work. There might be a simpler version but I am fairly sure this will work reliably and uses cheap automotive relays.

When both sensors are exposed, they both turn on. RL1 is turned on by the low level sensor, and the output of the high level sensors then connects to RL2 and RL3, so they both turn on. RL3 turns on the auger motor.

RL2 connects the output of the high level sensor to both RL2 and RL3, so both RL2 and RL3 will stay turned on when the lower level sensor is covered, it turns off and RL1 turns off.

When the high level sensor is covered, it turns off. RL2 and RL3 turn off, so the auger stops. Now that RL2 is off, and RL1 is off, nothing will turn on when the high level sensor is uncovered.

 

[brent f]

Awesome!!
So grateful. Thank you so much.
I will post when I get it running.