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eBay Green Laser Pen – Unexpected High Power

Green Laser Pointer
Green Laser Pointer

Here’s a cheapo 532nm green laser pointer courtesy of eBay, this one rolled in at ยฃ7, with 18650 cell & charger included. Advertised at 1mW, I was immediately suspicious of the output power since this unit quite easily causes skin burns.

Laser Warning Label
Laser Warning Label

The warning label rates this laser at Class III, with an output power of <1000mW. Massively higher than the 1mW advertised. The end cap is split into two parts that are threaded – the first one is a starfield effect diffraction grating, while the second one moves the final optic to focus the beam.

Starfield Diffraction Grating
Starfield Diffraction Grating

The starfield gratings are mounted inside a brass ferrule, which can be rotated to alter the effect without unscrewing from the main body.

Optics Removed
Optics Removed

Removing the output optic barrel reveals the end of the DPSS laser module, which appears to be well glued in. The aluminium cylinder doesn’t appear to have any other purpose other than to protect the laser output end.

KTP Crystal & Lens
KTP Crystal & Lens

Unscrewing the cylinder reveals the glued holder containing the KTP crystal, and the first output optic. The beam from this alone is very divergent, expanding to ~100mm over a meter or so. The beam right at the optic though is highly focussed & is quite capable of cutting through black electrician’s tape.
There’s also no IR filter anywhere in the optical path – so there is going to be a high power 808nm/1064nm component to the beam since these wavelengths are used in the DPSS process. Since these components are totally invisible, the risk for eye damage is higher due to lack of a blink reflex.

Power Reading
Power Reading

On to the power reading… 351mW of output at 532nm. So quite a bit more than the advertised spec then, but lower than the warning label states. This puts this unit into Class IIIB.

Cell Capacity
Cell Capacity

From a full charge, down to 2.8v, the “4000mAh” cell provided with this unit managed a pitiful 1128mAh. I knew from the second I got this cell that it would be a fake, since decent 18650 lithium-ion cells cost about the same as this whole package.

Fake Cell
Fake Cell

This cell claims a 4000mAh capacity, and built in protection circuit. Let’s dig under the sleeve…

Nope. No protection circuit here. It’s easy to tell anyway – protected cells are longer, and usually the strap buggering off to the other end of the cell is visible through the sleeve. There is a dual-layer sleeve though, of clear PVC under the BRC branded one. No other markings on the cell at all, and it’s suspiciously light in weight.

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SkyWolfEye Cree XM-L 18650 Torch

It’s been a bit quiet around here for a couple of weeks, as it’s the run-up to Download Festival here in the UK, so I’ve been busy sorting everything out for that. Just in time a new order has come in!

Due to a small accident with the old Maplin torch from a while back, (turns out they don’t float when dropped in the canal – ooops), a new one was sourced. Maplin is very expensive considering the imported crap they peddle these days, so I figured eBay would be the best bet for cheap imported crap ๐Ÿ˜‰ This unit came with a few accessories, so I’ll start with the torch itself.

18650 Torch
18650 Torch

This is an aluminium unit, and does feel quite well built for the price, but it does have a few disappointing things. The lens assembly at the front is movable so focus the beam – the range goes from wide flood to a very small spot.

Power Switch
Power Switch

The power switch on this torch is at the back on the cap, covered by this obscenely brightly coloured cap.

Lens Assembly
Lens Assembly

The lens is a simple plastic moulding, but it produces a nice wide beam.

Enthusiastic Numbers
Enthusiastic Numbers

On to the battery supplied – this claims to be a 5.8Ah 18650 cell, which as far as I’m aware do not exist. I’m always dubious of lithium-ion cells from eBay, the Chinese seem to be well into a race to put the biggest numbers that will fit on the label. (I’ve even seen a USB powerbank claming to have 100Ah of capacity!). The largest capacity cells I have at present are LG HG2 18650s, and those are only rated at 3Ah a piece. They’re also relatively expensive.

Label
Label

The manufacturer couldn’t even get the label spelling correct! Although they do apparently have a 10 year “sheef” life. Never seen that from an 18650 either. They tend to discharge on their own if left unused in about 12 months. I wouldn’t like to think of what the self-discharge rate of these dodgy things is, and I don’t intend to keep them to find out either!

Battery Capacity
Battery Capacity

After a quick blast on the charger to top them up, on the discharge tester they go! This test was conducted at 1A, and this now shows the true capacity of 1.439Ah, which is honestly better than I was expecting. Already having high quality cells I wasn’t fussed about this aspect of the purchase, I knew these cells would end up in the bin.

LED Module
LED Module

Unscrewing the lens housing at the front gives access to the LED module – this is a Cree XM-L die in here, although it might not be a genuine Cree (or possibly a factory reject). The LED housing is aluminium, the LED uses this as a heatsink.

Positive Contact Spring
Positive Contact Spring

Nothing special about the back of the module after it’s been unscrewed from the barrel. There’s a couple of O-Rings to seal the sliding lens assembly, I lubricated these with some silicone grease to try & make the housing somewhat splashproof.

Control PCB
Control PCB

The control PCB is pulled out of the housing to reveal the circuitry. The LED is controlled by a SOT-23 mode IC & a SO-8 MOSFET. There’s nothing complex about the LED current limiting, just a bunch of SMD resistors in parallel to set the limit. This torch, like 99% of Chinese import torches from eBay, has a multi-mode IC with SOS & strobe. I don’t need this crap, and it’s easily bypassed.

Modifications
Modifications

Here I’ve desoldered the MOSFET from the board & jumped across it’s drain & source connections, converting the torch to simple ON/OFF control.

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eBay Special – LED Disco Light With Built In MP3 Player

Here’s an eBay oddity – it’s got the same light & lens mechanism as the cheap “disco light” style bulbs on eBay, but this one is battery powered & has a built in MP3 player.

MP3 Disco Light
MP3 Disco Light

This device simply oozes cheapness. The large 4″ plastic dome lens sits on the top above the cheap plastic moulding as a base, which also contains the MP3 player speaker.

Controls
Controls

There are few controls on this player, the volume buttons are combined with the skip track buttons, a long press operates the volume control, while a short press skips the tracks. Several options for getting this thing to play music are provided:

  • Bluetooth – Allows connection from any device for bluetooth audio
  • USB – Plugging in a USB flash drive with MP3 files
  • SD Card – Very similar to the USB flash drive option, just a FAT32 formatted card with MP3 files
  • Aux – There’s no 3.5mm jack on this unit for an audio input, instead a “special” USB cable is supplied that is both used to charge the built in battery & feed an audio signal. This is possible since the data lines on the port aren’t used. But it’s certainly out of the ordinary.
Top Removed
Top Removed

The top comes off with the removal of a single screw in the centre of the lens. The shaft in the centre that holds the lens is attached to a small gear motor under the LED PCB. There’s 6 LEDs on the board, to form an RGB array. Surprisingly for a very small battery powered unit these are bright to the point of being utterly offensive.

Mainboard
Mainboard

Here’s the mainboard removed from the plastic base. There’s not much to this device, even with all the options it has. The power switch is on the left, followed by the Mini-B USB charging port & aux audio input. The USB A port for a flash drive is next, finishing with the ยตSD slot. I’m not sure what the red wire is for on the left, it connects to one of the pins on the USB port & then goes nowhere.

Audio Amplifier
Audio Amplifier

The audio amplifier is a YX8002D, I couldn’t find a datasheet for this, but it’s probably Class D.

Main Chipset
Main Chipset

Finally there’s the main IC, which is an AC1542D88038. I’ve not been able to find any data on this part either, it’s either a dedicated MP3 player with Bluetooth radio built in, or an MCU of some kind.The RF antenna for the Bluetooth mode is at the top of the board.
Just behind the power switch is a SOT23-6 component, which should be the charger for the built in Lithium Ion cell.

Lithium Ion Cell
Lithium Ion Cell

The cell itself is a prismatic type rated in the instructions at 600mAh, however my 1C discharge test gave a reading of 820mAh, which is unusual for anything Li-Ion based that comes from eBay ๐Ÿ˜‰
There is cell protection provided, it’s under the black tape on the end, nothing special here.

The main issue so far with this little player is the utterly abysmal battery life – at full volume playing MP3s from a SD card, the unit’s current draw is 600mA, with the seizure & blindness-inducing LEDs added on top, the draw goes up to about 1200mA. The built in charger is also not able to keep up with running the player while charging. This in all only gives a battery life of about 20 minutes, which really limits the usability of the player.