IR Source

This device is essentially an IR flashlight with a single IR LED.  UV light sources are a dime a dozen, but IR sources are thin on the ground, probably because no one ever needs one anyway. None the less, I've made one.  I built in a couple of extra features for no good reason that I can think of other than that I wanted to.

There are no on-board batteries.  Power should be 5-6 V DC to the 5.5 mm barrel jack with the pin positive.  The device is push-button activated;  there's no hard on-off switch.

If you like the battery that's visible in a couple of the images it's at...

https://www.thingiverse.com/thing:6036477

There is a red LED in the cover to provide some confirmation that there is in fact current through the IR LED.  

The pot controls current through the LED pair, which are in series.  With the specified supply voltage, the current range is approximately 2-18 mA.  An ammeter connection port is built-in and can be accessed by removing the jumper and connecting the meter those two pins.

If a more complex IR output for a particular purpose is needed an Arduino can be connected through the ammeter port.  Connections should be an Arduino output (analog or digital) to one of the ammeter pins (only one will work; see schematic) and the Arduino GND pin to the female Dupont ground pin connection on the face of this device.  Don't use the other ammeter pin for the ground; it won't work.  Used with an Arduino, any external power source should be disconnected. The pushbutton will not be functional.  The LEDs will follow Arduino output.

This whole device could have been considerably smaller than I made it, but I used the circuit board I had, 70 X 30 mm.  I guess I'd rather be faced with putting five pounds of stuff in a ten pound box than vice versa.  

The push-button mounting is from an earlier model, the first thing I ever posted.  Will post here soon.

https://www.thingiverse.com/thing:4886430

The model file for the pushbutton mounting brackets is included in this posting so you don't really need to follow the link unless you're interested in more detail on the pushbutton mounting.

There's an LED washer/spacer to keep too much of the IR LED from protruding from the end 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.

Most of the wiring is 30 ga. solid, using wire wrap where possible.  The exceptions are where I used solid breadboard jumpers (22 ga?) for some connections on the board.  When placed on top of the board and soldered below, the extra lead end can be bent over and soldered again to the connecting pin of an adjacent component or left standing as a post to wire wrap a lead from an off-board component.

Bill of Materials

3D-Printed parts:

- Case
- Cover
- LED Washer
- Pushbutton Hold-Down (2 req'd)

Purchased or parts box parts:

IR LED, 5 mm

https://www.amazon.com/gp/product/B01BVGIZGC/

Red LED, 3 mm

5.5 mm panel mount barrel jack

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

Tactile pushbutton, normally open (length suitable for 2 mm through-wall installation)

Small nylon cable tie (pushbutton mounting)

70 X 30 mm perf board

https://www.amazon.com/IIVVERR-Experiment-Universal-universal-experimento/dp/B08LDWQLW4/

1 K pot

68 ohm, 1/8 watt resistor (blue, gray, black)

2 pin male pin header

1 pin female pin header

Pin header jumper

30 ga. solid wire

Breadboard solid wire jumpers

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

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

M2 X ?? mm 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)

Cyanoacrylate gel (pushbutton mounting brackets and IR LED spacer)

Printing Notes:

- PLA

- 0.3 nozzle

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

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

- Infill: 12%

- Shells: 0.8 mm, horizontal and vertical