I'm looking for some help from the folks that know more about this subject than me. I'm trying to install a break beam sensor to turn on/off an electric 6 rpm motor. It powers a collator for a reloading press. I currently have the motor hooked up to a 9v power modulator. I'm not sure how to hook up the break beam sensor Sensor in order to turn the motor off when a feed tube is full. Where does the signal wire hookup to? Do I need a relay for the sensors?

They make these assemblies, but are rather pricey ~$500... So i decided to build my own.. Any who, I'm stuck on this step. Any help would be greatly appreciated. Feeder Assy.

  • \$\begingroup\$ You need a relay to the motor, and did you read the tutorial learn.adafruit.com/ir-breakbeam-sensors \$\endgroup\$
    – Trevor_G
    Commented Sep 29, 2017 at 19:35
  • \$\begingroup\$ I did. However, I did not find / understand the information I was looking for. \$\endgroup\$
    – Wannalearn
    Commented Sep 29, 2017 at 21:37

1 Answer 1


You can use these but the invisible IR light ought to be confined so it does not spread out and bounce off anything. I usually mount both behind an aperture with a deep hole only small enough to see the target behind the object blocking the recessed light path, which is only 3mm, but a 4mm hole x 10mm deep might be ok to ease alignment of the single piece assembly around the tube. Trial and error may be necessary so it ignores stray light yet is not attenuated too much thru the plastic tube. There will be light scattering and diffraction but how much is hard to say.

It says that it reaches 10" but with LED angle of 10 degrees that reflects a big target so your range is reduced with this and a more powerful break sensor ( eg 5mm LED) is needed. Your contraption might work but the light must not wrap around the clear cylinder and get in. A visible LED can be used to see how light refracts into your receive aperture, for understand and alignment is key.

da specs

  • Power Voltage: 3.3 - 5.5VDC
  • Emitter Current Draw: 10mA @ 3.3V, 20mA @ 5V
  • Output Current Capability of receiver: 100mA sink
  • Transmitter/Receiver LED Angle: 10°
  • Response Time: <2 ms

Since the output is an open collector switch to ground of 100 mA, you can amplify this max current with another transistor FET or PNP emitter follower or low side of a relay to drive your solenoid with a reverse biased clamp diode to its DC supply.

Details depend on your load.

Position depends on the inertia of motor after current is open. The surge current of your motor is typically 8~10x its rated current, so plan on this.

p.s. I might be inclined to adhere them into the acrylic or polycarbonate tube if it looked like it might work. But try on a sample first. Get two they're cheap. Use Shielded pairs for everything to avoid motor cutoff re-triggering the sensor. Maybe an RF cap on output...

  • \$\begingroup\$ I appreciate your time and help in this. Could i add a Power relay feather board along with the break beam sensors? Would that accomplish the circuit? or would i need to solder and make a more complex circuit? \$\endgroup\$
    – Wannalearn
    Commented Sep 29, 2017 at 21:04
  • \$\begingroup\$ does a feather board need more than 100mA DC to drive it? 9 VDC Rated current 77.8mA is that it? or 12V or more ,, will be less current. \$\endgroup\$ Commented Sep 29, 2017 at 21:30
  • \$\begingroup\$ I was looking at this one... adafruit.com/product/… \$\endgroup\$
    – Wannalearn
    Commented Sep 29, 2017 at 21:38
  • \$\begingroup\$ nope that one is 3V \$\endgroup\$ Commented Sep 29, 2017 at 21:50
  • \$\begingroup\$ You need a DC supply to match >=9V relay coil to get 77.8mA or less and 5V for the sensor \$\endgroup\$ Commented Sep 29, 2017 at 21:52

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