Why consider alternatives to tracer units?
In a word, Flexibility.
Tracer units are handy and they work but they are bulky, especially on a sidearm and restrictive.
Some owners just want to have a different look.
Not using one also means the following:-
Not having to use an outer barrel with the required thread.
Not being hindered from using a hop up or silencer of your own choosing.
Not having to charge a separate device or having it fail while your battery is still going.
Not having to have multiple tracer units or move one from blaster to blaster.
It’s nice to have a choice.

How can an LED do the same job as a tracer unit?
It’s just physics.
To explain, I’ll use some typical numbers for RPS and FPS.
RPS or fire rate ranges from a low 6 to a ridiculous 40+ depending on motor speed, gear ratio and battery voltage. FPS or gel speed varies from the low 120s to 400+ depending on the spring, stroke, volume, barrel and the gel.

At a rapid 20rps a gel transits the 1cm in a typical tpiece in 50ms.
In contrast, a gel at 250fps zips past a 7.5cm long tracer unit with its rows of 6-8 SMD UV LEDs at the muzzle in about 1ms. That is a huge difference in charge time even with that many cap assisted LEDs.
The faster a gel is moving, the harder it is to give it a charge, so why do it when it is moving the fastest?

Standard LED, UV LED, Cree LED or LASER LED?
Its all about intensity and energy.
Visibility to our eyes does not equate to energy. The shorter wavelength end of the spectrum has the higher energy. Hence the use of UV, which is just beyond the shorter blue end of the visible spectrum, (it is why we get sunburn and skin cancer from UV).
Cree LEDs do produce more visible light but not more energy. Besides, most blasters and mags are not light-tight so Crees are more likely to give you away to the other side. UV by comparison is borderline on visibility.
LASERs are too narrow. You want to charge the whole gel.

What Voltage?
UV LEDs like most LEDs work at a forward voltage of 3.4 - 5v.
If using a battery in the mag then a 3.7v lithium would be ideal.
Mag terminals usually receive the same voltage as the motor 7.4 - 11.1v.
Some are powered separately from the circuitboard and regulated to 6 - 8v
Using pre-wired UV LEDs that work from 3 - 12v eliminates all these considerations.
Naturally gels flashed via the mag or motor from an 11.1v battery will shine better than from a 7.4v.

Will it prematurely drain the battery
UV LEDs measured a 6mA draw on 7.4v when lit continuously.
In comparison a mag motor draws around 60mA while a blaster motor will draw 1.5 to 2.5A after the initial surge which can spike well above 10A.
The current draw from LEDs, even in multiples is therefore insignificant.
In fact, they’re so cheap and low powered that you can leave them permanently installed in every blaster.

Why not illuminate the whole mag?
You can.
Light intensity drops exponentially with distance.
Initial tests involving flashing different LEDs next to jars of gels showed that only the few immediately next to LEDs glowed properly and for a useful length of time.
As glow gels are not transparent, the ones behind these do not get much charge.

Where would you place the LED?
Anywhere along the path from mag to barrel will do but the tpiece is preferable.
There are many reasons but main ones are:
It is outside the gearbox (in most cases).
Accessibility for wiring.
There is more space than in the tube leading to it although you can as long as you locate the LED flush with the sides.
The glow fades quickly and flashing the gels just as they are about to be sent down the barrel is only logical.
On a side note, there is the possibility of having a switch to the LED so you can turn off the charging at any time. This will not be possible if you pre-charge all the gels in the mag.

Can you Prolong LED Illumination time?
Wiring electrolytic capacitors, 100 - 400 microfarad in parallel with the LEDs and diode isolated do help them stay on longer, but is not needed. The glow gel has ‘left the building’ so to speak even as the light from the LED slowly fades.

Is 1 UV LED enough?
Thus far 1 LED in the tpiece has proved to be plenty. This is probably due to the aforementioned exposure time.
I have wired multiple UV LEDs as well, both next to each other along the feed tube to the tpiece and on either side of the tpiece. No noticeable improvement was noted.
The glow does appear slightly more intense but like the single LED fades within 30s.

What do you connect the LED to?
I recommend wiring in parallel to the mag terminals although there is a catch. Wiring to the mag means the first few gels are charged when you charge the blaster. If you do not want this then it is better to connect the LED to the motor. That way the gel is only charged when you pull the trigger.

In blasters where mag feed is mechanical like the deagle and the G36 or is hopper-fed like the M1911, P90 or F2000, wire it to the motor.
In blasters where the tpiece is easily detachable, add a connector.
In manual blasters you will need an alternate power source, the JY AWM being an exception.

Can I use it mixed with other gels?
Of course. Do take into account the gel size and weight when mixing as the trajectories may differ to some degree.

Do I need to make any major mods to the blaster?
You will need to drill a 3mm hole.
Depending on how you intend to mount the LED, I usually grind the LED to create a flat tip which I then bevel and buff to reproduce a smooth and clear face for best light transmission.
The LED body has a slight taper and will usually stay in place without gluing.
If you think it’s too difficult, see your local GB seller or tech.

Where do I get these pre-wired UV LEDs?


Thanks for the great writeup, @Cruise!


@Cruise, any chance of some pics of your install (and links to your UV LED sources)?

Here u go. Same installation with longarms but I don’t have pics of those. I will take some.
Gel feed and a smooth flow of gels is important as the rate of fire goes up so having the LED just before the tpiece and flush with the walls is preferable.
You want to charge the gel and those immediately after it as close to sending it down the barrel as practicable.

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Thanks for the write up, I’ve been looking for the time to set mine up. Now you’ve got me excited to get it sorted I’m just gonna find the time and do it. I was also gonna try jam 2 leds in above the t piece but might see how 1 goes after your recommendation.

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Make sure it is flush.
You can grind down the LED till about 1.5mm from the elements within.
You need to take into account the size and path of the nozzle and where the gel sits just before it is pushed into the barrel.
Putting the LED into the tube before the tpiece takes away those considerations.
A - recommended
B - 2nd LED or same as ‘A’ but on opposite side
C - alternative to ‘A’ if tpiece is enclosed in gearbox.


I use a pre made lit mag bought from an AU shop. Works a treat gels stay lit for over half an hour.


So long as you’re happy, it doesn’t matter how you get there.


I had a go doing this, so thanks very much @Cruise. All wired up (I soldered a XT30 connection to the mag terminals in my SCAR for easier removal—especially as I glued my LED in). Everything seems to be working fine, I just need to pick up some glow gels for testing—anyone have recommendations?


Looking good.
As the LEDs only draw .020amp, any lightweight wire will do. In some cases I’ve use wire wrap wire which is only single strand. Makes it easier to run the wire and not worry about it pulling or vibrating as much.
I’ve since worked out that the pre-wired 470ohm is overkill with strictly 7.4v pistol setups and even half that, a 220 or 270ohm resistor will work and provide more charging.
The LEDs prefer 3.5-4.0v (5v max) and you’re basically using the resistor to drop the battery voltage by .02 x R volts to get it to the working voltage of the LED.
560 for 14.8v,
330 for 11.1v and
180 for 7.4v are optimal

I mostly use WI Glow gels.
They’re closest in size to the WI Reds I use and have similar trajectories.
Have fun.

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Yeah I am using the WI Glows also.
The Ausgel ones seemed to be hit and miss for a mate of mine, and I always used the WI red packs to great effect.
The glows are definitely bigger though…my tightbore didn’t like them…and as I’m too lazy to grow to size, I decided I didn’t like my tightbore…


My brain is hurting

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@Karl07… good to know. I’m running 7.5mm alloy barrel across the board, so fit shouldn’t be so much an issue for me. Which is just as well, as most of my local suppliers seem to be out of stock of the LDT/WI glows… which leaves me with just the Ausgels. Will try to pick some up this week and see how they go.

Anyone know if any of the local (north Brisbane) stores are open (yet)? Didn’t have any luck getting through to M4A1 in Chermside today.

I changed to the Ausgel 7.5mm too.
I got my WI stuff from CEH Salisbury.
I know that M4A1 in Morayfield is open from being told so, and I definitely know X-Force/Vipertac is open in North Lakes because I was there today…and picked up a set of AusGel Ultras…can’t wait to try them

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Thanks @Karl07! Have you tried X-force’s “own-branded” glow gels?

From my own measuring, the WI glowgels do average 0.2mm bigger than WI Red/Milkies but I have had no problem with them in a 7.0mm tightbore from a 50cm sniper doing 300fps down to a 10cm pistol at 200fps.
Perhaps I’ve been lucky or maybe it’s because they’re not as hard as the Reds.


AussieByrd, no I haven’t…im the person that, once I know what works, I wont change.
I HAVE had good results out of CEHs hardened gels as I was given some to try…surprised me. I ended up with 1kg to use so I use them in the SAW because its cheap to use…I average about 10-15k gels in a day with it haha.

Cruise, I will have to take your word for it as I never tried, but when I first put them through the tightbore in the SAW it jammed them up before a single gel came out the end. Cleared and tried again, same result.
Never had an issue with any other gels…other than softer gels just exploding from the FPS…even the glows sometimes fly apart. Hence why I generally use hardened only.
Its putting out 330-340 FPS.
Also had the same issue with my 310 FPS M4 DMR with a longer tightbore…which now also has a 7.5mm


I ran WI green tracers through a 7.3 copper alloy barrel with no issues. They’re my go to tracer gells. :+1:

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Yeah I wanted a 7.3 but I was too impatient to order them…

FYI… M4A1 Chermside is open… I picked up some AusGel glow earlier in the week.