New guy needs help with project please

I need help designing and implementing a simple project please.
I need to activate a trigger, (hopefully a non contacting proximity switch), have a 12 volt, (less than 1 amp draw), motor instant on, run for from .5 to 10 sec, and shut off until the trigger is deactivated and reactivated.
I would like the controlling device to be powered by 12 volts and the motor circuit needs to be able to use from 5 to 24 volts 2 amps.
I need help picking out hardware and with wiring.
Thank you for your help.

Hi sawgunsmith,

Welcome to the Tech Forum.

What sort of thing/object would be activating the trigger?

A sliding aluminum bar.

The aluminum bar would slide towards and away from the trigger.
I have an 18mm hole in which to put the prox sensor through and the bar will be from .5" to 2" from the bracket I have designed and gotten printed.
A prox sensor with a flush mounted or not exposed end and of approximately 18mm diameter would be desirable.

So your sensor needs to detect your bar somewhere between 0.5" and 2" away? Is this a one-off thing for your shop or a production product?

.5" to 2" is the travel of the bar and .5" is the clearance between the end of the bar fully extended and the bracket. Consideration will need to be taken when picking the sensor so it senses the bar between 0 and .25" hence the need for a flush ended prox sensor.
This is a one off I’m afraid. If this turns into a marketable solution, the market will be somewhat limited.

Well, if you are looking for an inductive type proximity sensor, the range will be reduced when sensing aluminum compared to ferrous-type metals by about 60%. For instance, the GX-318MLK-A-N will pick up a “standard” sized iron object about 10mm away, and an aluminum one of the same size about 4mm away.

Here and here are a couple links to some of our cylindrical inductive sensors, arranged by price. They list the sensing distance for iron, so you’d need to multiply that number by about 0.4 to get the typical max range for aluminum.

We also carry optical reflective type sensors such as these and these. Most of these are not in a cylindrical form-factor, but they do have the advantage of not being affected by surrounding metal.

Finally, we carry reed switch sensors which sense when a magnet is nearby. If you attach a magnet to your aluminum bar, these can pick that up when close by.

The 4106-600XU-A-1-CU-ROHS-ND is a cost-effective time-delay relay for taking the output of the prox sensor and controlling a timed internal relay to power the motor. You would set it up in “Single shot (I)” mode for your particular application, as shown on page 2 of its datasheet.


The relay output on this device is rated for 5A, which should be enough to handle the start-up surge of your motor. If it’s still not enough, you could take the output of this relay to activate the coil of another higher-current rated relay. It’s designed to be mounted on a DIN rail.

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So, I don’t need a separate power supply for the motor? That’s great.
I am confused about the wiring though. Would you help me with that please?

Would you please explain how I should hook these things up? I’m a machinist and gunsmith and not an electronics guy. I don’t understand the symbols and things that you guys do so something in crayon on a sheet from a Big Chief notebook would do the trick I think.
Thank you.

OK, here’s a start. The sensor connection depends on which sensor you select. The timer relay is looking for a short from “25” to “A1”.

I will say that the simplest would be if you could use one of the reed switch sensors, but you’ll have to see if you could use one of them. They are the ones that require you to attach a magnet to your aluminum bar. When the magnet gets close, it closes a switch inside the sensor. For other types, we’ll have to see, based on the specific datasheet.

  • Your power supply positive lead goes to A1, negative to A2.
  • Your motor power supply positive lead goes to “15”.
  • Connect a wire from “18” to positive terminal of motor.
  • Negative terminal of motor goes to negative lead of motor power supply.

When “25” detects 12V via your sensor, it triggers it to turn on for set time.
Timer relay is configured for “Single shot (I)” mode, and then time is adjusted using other two knobs.

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Thank you very much. That is a great explanation.
If I choose this prox sensor, , it has three wires. That puts me in a grey area again as far as what to do.

The three wires are for normally open and normally closed?

I believe that you’ll want a “PNP normally open” (NO) type of output for your sensor. So, the E2B-M18KS08-WP-B1 2M is the same part with that output.

This one will bring the voltage up to the supply voltage when turned on, which is what you need.

Here’s the connections for using the E2B-M18KS08-WP-B1 2M

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Reed switch does look easier. Thank you again.

My project turned out really nice. Works like a charm.
Thank you for your help and I hope I can come back to you in the future.


Glad it worked out! So which sensor did you end up using?

I used a reed switch from a window security system for the trigger. I glued little neodymium magnets to the aluminum bar and stacked them up until the switch triggered. I used a single power supply to power both the time delay relay and the motor once I got it through my head that I needed a separate power supply for the motor. Your explanation was plenty clear, it was my head that got in the way.
I did my best to keep everything neat and tidy and put everything in wire loom and I couldn’t be happier.
I’m sorry I didn’t order from your company but Amazon has a vastly superior delivery time line and I have been very anxious to get this part of this project finished.
I have more projects in mind and will need assistance with them and I hope you will be available for consulting.
One project involves checking the level of fill in a container as it is going by a position. My space for a device is very limited and I can not stop the motion. The motion is not very fast so capturing an image or bouncing a laser off of the inside of the container shouldn’t be impossible. the space for a device is probably going to be the limiting factor.
Anyway, Thank you very much for your help.

Hello Scott,

What is the container type for this fluid? If it is glass or plastic, you may be able to use a capacitive proximity sensor.

It may be necessary to use a pair of sensors as a single proximity sensor will not be able to differentiate between nothing and a half-empty container.

On a related note, you may need to use some logic to make the determination. Let us know if you would like to explore alternatives.

Best Wishes,