IR Detector

This is a general purpose IR detector with LED and buzzer indication and adjustable sensitivity.

This model complements my IR Source...

https://www.thingiverse.com/thing:6497222

...using the same case style. Together, the two constitute a self-licking ice cream cone, but may be useful as testing tools. The detector responds to sunlight, a solid IR source and the encoded output from IR remotes.

There are no on-board batteries. Power should be 5-6 V DC to the 5.5 mm barrel jack with the center pin positive. There is a latching push-button on-off switch.

The sensor is a photodiode IR receiver in the end of the case. There are a pair of LEDs on the top cover, red for power indication and white for IR indication. There's a buzzer, with a DIP switch to silence it if desired. The pot adjusts sensitivity.

There's a washer/spacer to keep too much of the 5 mm photodiode from protruding through the end of the case. It gets glued on the inside of the case.

I used threaded brass inserts in the case for the cover screws. Since there are no batteries requiring the case to be opened from time to time, this is overkill, but I like 'em.

The holes in the case are sized to accommodate the brass inserts. They don't need to be heat set. They can be pulled in cold from the bottom using a long M2 screw with a nut and flat washer. It's a three-step hole, with clearance, then the pull-in fit and finally a shoulder that will prevent the insert from pulling through. If you're dead set against the inserts you could probably get away with using M2.5 self-tapping screws with the existing holes in lieu of the M2 machine screws, but the counterbores in the cover for the M2 washers are not large enough for M2.5 washers. You'll have to omit the washers.

The internal wiring is all 30 ga. solid, using wire wrap where possible.

I made a custom PCB for this project but it can be done with a common 80 X 20.5 mm project board (28 holes X 6 holes). The screw post spacing in the case fits that board. I've included an image of an early version of the project board with some components installed but it lacks one of the resistors and a right-angle pin header at the end for the off-board connections.

If you have a small CNC mill and wish to make your own circuit board, message me and I'll send the nc files for milling the board. This was my first self-made PCB and it worked just fine, though not without some learning curve adventures on the mill along the way.

The circuit uses one side of the LM358 dual Op-Amp chip. Three of the pins are unconnected.

Bill of Materials

3D-Printed parts:

• Case
• Cover
• LED Washer

Purchased or Parts Box parts:

IR Photodiode, 5 mm

https://www.amazon.com/gp/product/B01BVGIZGM/

Red LED, 3 mm

White LED, 3 mm

5.5 mm panel mount barrel jack

https://www.amazon.com/gp/product/B01N8VV78D/

Latching Push Button Switch, panel mount

https://www.amazon.com/gp/product/B07VCJ11RZ/

80 X 20.5 mm Project Board (28 X 6 pin holes, 4 mounting holes)

https://www.amazon.com/uxcell-Universal-Printed-Circuit-Soldering/dp/B07FK3NLG2/

LM358 8-pin IC (dual Op-Amp)

8-pin IC socket

5 Volt active buzzer

Single DIP switch (buzzer isolation)

10 K pot

220 ohm, 1/8 watt resistor (red, red, brown)

10K ohm, 1/8 watt resistor (brown, black, orange)

1.5K ohm, 1/8 watt resistor (brown, green, red)

4-pin right-angle male pin header

M2 X 4 mm X 3.5 mm brass threaded inserts (4 req'd)

https://www.amazon.com/gp/product/B07VBRF7P2/

M2 X 8 mm round, Allen or pan head machine screw (cover, 4 req'd)

M2 flat washers (cover, 4 req'd)

M2 X 6 mm round head self-tapping screws (PCB - 4 req'd)

30 ga. solid wire

Cyanoacrylate gel (IR LED spacer; red and white LEDs)

Printing Notes:

PLA

0.3 nozzle

Layer height, Cover: (0.75 mm layer height, print with face down)

Layer height, Case: 1.5 mm layer height, print with open side up)

Infill: 12%

Shells: 0.8 mm, horizontal and vertical