I have a project , I know what I want it to do but don’t know how or the components needed.

I want this IR beam-break trigger to control two of these 12v magnets (.33A each). When the beam is broken, I want the magnets to release. As soon as the beam is restored I want the magnets to re-energize.

The 12V power supply is a battery commonly used on lawnmowers. The IR emitter and receiver are 5.5V and 20mA. The distance between IR Emitter and Receiver is 6”.

I know this is a simple circuit for most of you but I need help. I don’t know how to make the 5V IR break beam control the 12V relay. Your help would be appreciated. This old man needs help.

  • \$\begingroup\$ Milli amps are "mA" and not "M". "MA" is reserved for mega amps. Don't quibble in case you are thinking of doing so because accuracy in all areas is required in engineering. \$\endgroup\$ – Andy aka Feb 4 '16 at 8:39
  • \$\begingroup\$ Question updated with links to OP's specified parts. \$\endgroup\$ – Robherc KV5ROB Feb 5 '16 at 4:03

Here's a diagram of a basic circuit that came to mind while reading your question. Ideally, this may fulfil your need, but otherwise it at least gives us somewhere to start from.
New IR Trigger

  • In this circuit, D1 is your IR LED & "sensor" is your detector.
  • The 10Kohm resistor is required by your detector.
  • Q1 is a [IRLML6344TRPBF][2] MOSFET ($0.36 @ digikey.com). It "turns on" completely at ~4.5V signal level (so your 5V detector circuit can run it), and can handle ~10x your rated load from your solenoids & 2.5x the voltage; so no relay needed.
  • The diode parallel to Q1 "freewheels" to keep coil inductance from causing overvoltage & destruction to Q1 (Q1 has an internal diode to do this to, but better safe...).
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  • \$\begingroup\$ Here are the parts I have ordered. IR Break Beam Sensor adafruit.com/products/2167 Electromagnet Solenoid Specifications: ebay.com/itm/… Model XRN-XP25x20 Rated Voltage DC 12V Rated Current 0.33A Lifting Force 5Kg/ 11Lb Overall Size 25 x 20mm / 1" x 0.8"(Dia.*T) Thread Hole Dia 4mm Lead Length 23cm/ 9.1" Materials Metal, Electronic Parts Weight 53g Package Content 1 x Electromagnet Solenoid \$\endgroup\$ – Richard Constantine Feb 4 '16 at 22:35
  • \$\begingroup\$ Robherc KV5ROB here are the components I have ordered, I haven’t ordered the relay. Advice on the relay would be appreciated. IR Break Beam Sensor adafruit.com/products/2167 Electromagnet ebay.com/itm/… \$\endgroup\$ – Richard Constantine Feb 4 '16 at 22:49
  • \$\begingroup\$ Answer updated with new circuit, based on your specified parts. \$\endgroup\$ – Robherc KV5ROB Feb 5 '16 at 3:57
  • \$\begingroup\$ Robherc KV5ROB I appreciate the quick response and the circuit design. this will work well for my project. \$\endgroup\$ – Richard Constantine Feb 5 '16 at 4:56

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