Laser Head Diode Dot Module WL Red Mini 650nm 6mm 3V 5mW 10PCS

These laser diodes work very well with 2 AA or 2 AAA batteries directly (3V DC). While the lens in the front seems to be fixed with a drop of glue or something, a little force will allow you to twist the lens slightly and focus at the distance you wish. Remember, with laser diodes, a very small change with the focus will result in a blurry or sharp dot at the distance you wish. Make sure the lens is clean - and do NOT apply overvoltage or you'll have an "LED laser" that won't focus (you ruined it). Also, these diodes are easy on batteries - better than many pointers that go through batteries quickly. I've replaced pointer diodes with these (carefully) and they outperform the original diodes in brightness and battery life. Note they are small barrels, which makes them great for smaller projects. But for pointer use, you may need to put into another spacer barrel to fit inside a 2x AA or AAA barrel size. In the pack I got there were NO duds and all worked perfectly. The only issue was the focus was not uniform across most of them. Easily fixed as posted above.

These lasers are a bit delicate as is (small wire/solder joint) But, they are bright and work very well for laser trip wires or whatever small laser project you would like. Plus the small recess around the middle of the housing makes it easy to fit into hole when you use a small rubber O ring.. Well worth the time and price..

Apply 5V and you have a bright, red dot laser similar to the laser pointers that are so common now. The spot is reasonably small for non-critical uses and can be used from say less than 1 foot perhaps 40 feet. Indoors the spot is visible in the daytime. Outdoors the spot can bee seen if standing nearby, but at a distance it depends on the ambient light, colors, and surface finish around the spot. I did not confirm the focus adjustability by twisting the front ring because the two lasers I needed had a small enough spot for my needs at 60 inches. The stranded wires are about 28 gauge and therefore will be challenging to strip without the appropriate tool. Since they are stranded, they are not stiff or brittle and can take a modicum of flexing for a small number of cycles. I put heat shrink tubing over my solder splices to make the connections more reliable. I made sure there was no load on the laser module wires since they are only 28 gauge.

Amazing for the price, but I've experienced a pretty high failure rate with these-- nearly 50% stopped emitting brightly after a while (basically useless, just dim red, no beam). Even with that, they're still quite inexpensive, so I still recommend as long as you're willing to deal with the reliability issues. Their power "regulation" is just a resistor (91 ohms on the ones I received), which is cheap but prone to causing failure (variations in temperature and device characteristics can put current outside of safe range for the laser diode)... but they're sooo cheap.Another note-- they each have a plastic lens inside the housing, and you need to take care when heating for soldering or heat shrink (lens can be damaged be heat gun).

My need was to mark one line of 360 on a rotating plate to see how far from 0 the line would move..I.E.: as speed increased mark moves up the scale. Strobe and regular LED had too much scatter. These diodes are accurate enough for my use but not pin point beam as someone may need for an application I have not used these Diodes yet in the actual circuit to check the movement.. I bench tested them to see if they work first. I couldn't find any voltage drop figures so I assumed these 5 volt laser diodes dropped about 2.5 to 2.8 volts. For a resistor at 5 volts and ~ 20Ma (max as the mfgr suggest) 5.0 vin -2.5 V drop/.02Ma = 110 ohms for a resistor at 20 Ma 5 volts.. For safety testing, I used a 7805 reg set as current limiting right at 20 Ma. So far an OK laser diode. Don't know how long the diode will last set right at 20 mil. You'd think the mfgr. would give the device voltage drop. All in all for the price these Diodes seem to be OK for what i want to use them. Again not super accurate pin point beam fir someone needing that.

The dot on left is the dot from my cat's toy laser, nice dot. On the right is the shape I received from the laser diodes I just received that were supposed to be a dot. This is not a dot, it is a big rectangle instead. I would be happy to rewrite this review if they can provide me with laser diodes that actually give out a dot that resembles the dot to my cat's toy.

Nice little laser sources. I found that I can power them with anything from a USB 5V output to a 9V battery (in a pinch). You can focus them to a reasonable dot size. Overall, handy little lasers that are inexpensive and handle an range of power inputs.

Some of them look like red LED flashlights, rather than a laser. Very inconsistent. I used 40 so far and about 1/3 have problems with focus. Would not reccomend.