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Hutu Tracer Unit


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I must not be the only one who wanted a tracer unit that was integrated into the silencer making your gun about 3 foot long so I was looking up Hop up tracer units and if you want to buy one of them its like £ 30 for the special hop-up * bull shit* and £40 for the led unit to go onto your special hop up all sounds like such shit. So I went about researching and making my own cos £70 for a tracer unit is a bit crazy. 



So I went about researching it and a lot of people have done Hutu unit but don't document the process well and all have different setups so I'm just documenting the one that worked best for me. 



LED wise I used 3mm UV LEDs which have a common brightness which is about 3,000mcd which in common I couldn't find anything higher but if you could find a high mcd then I would say get it. It would be hard to as UV light doesn't register on the scale the same way. I have heard to use 12,000 mcd blue led but they didn't perform as well as the UV LEDs the reason for this is the substances the BBs are coated in react to UV light very well as you can see from the picture below. My chose is 3mm UV 3,000 mcd BBs


(UV light on bb picture ) 



BB colour is up to you but I tested Blue, Red and Green and green was the best one by far it gave the best contrast in most settings in most conditions obvious in the sunlight no matter what colour it's very hard to see. so my chose is Green BBs



Now that you know what LEDs and BBs to use it would be great to know what sort of equipment you would be using,


Hot Glue Gun

Black glue sticks 

Dremel / Rotary tool 

Rotary cutting disc 

Clear coat nail polish 

JST wires 


3.1mm Drill bit

Some Wires

Super Glue 

6mm Dowel 

UV led ( non diffused ) 


A battery capable of 30 amps

 that's all you need 


Prototype 1 

So on the prototype, I used two LED on an old plastic G&G sr25 to know what I needed to do, So I drilled two holes using a 3.1mm drill bit for the hop up once this was done. I then worked on the LED you to want to trim this down as low as you can without touching the element this will get a cloudy white colour an easy way to bring the clearness back is to apply a thin coat of clear coat to the LED leave these to dry I then insert the dowel into the bottom of the hop up so the led wouldn't interpret the path of the bbs I then used a little bit of super glue to hold the LED in place on the edge of the led so it doesn't diffuse the colour. The then wired LEDs up in series so connecting the positive to the negative side and adding the JST lead on hot glueing everything down to stop any light bleed out the side of the gun 




The BB glow was a little bit dead the glow was really weak so I would need to wire them into parallel and add in a resistor as my first prototype lasted 48 hours before the first led failed as my battery was delivering over 38 amps. 


Parrel or Series 

So after a little research, I realised that in series the battery voltage was cut in half for the LED so if I added more LEDs it would just decrease the voltage for each LED reducing the brightness so I would need to run it in parrel and so all the LEDs will get the same voltage allowing for a better overall performance 

 so I did a small test to compare brightness. 


In Series



In Parrell 



From this small test you can see the LED in Parrell are a fair bit brighter so for the second mockup I will add the two more LED brings the total to 4 and add in a 320ohms resistor. 


Prototype 2

For the second prototype, I added two more LEDs to bring it to 4 ass you can see comparing it is a fairly big difference in brightness I also added the resistor to the end of the positive LED leg that goes into the JST plug this limited the position I could put the cables into  feed the through the gearbox to the battery into pistol grip. I know what to do for the final unit I will be making. I had an idea of drilling into my prowin unit but I drill wasn't strong enough neither was my drill bit as one warped under the pressure and heat generated but the concept carried over. 



Final HUTU unit

for the final HUTU unit, I used an SHS plastic hop up which is the same as the Prowin and SHS aluminium, So I drilled out the led holes using the 3.2mm bit the same as the first prototype, cut down the LEDs and clear coated the same way. Glued them in the using super glue wired them up in parallel and added the JST plug onto the end.




I then added the resistor into the extension cable so it gave me way more space to flex the cable giving it a nice compact look and allowing the hop up unit to fit right and compact without getting in the way  



Once this is done I then connected everything in and made a bypass cable that allows me to run the Wolverine trigger board and Hutu of the same battery the one I'm using that give me a nice smooth 30 plus amps that give the Hutu enough amps to run at full brightness and the trigger board to run as it should. Turnigy Graphene 950mAh 2S 65C.


Below is the Hutu all wired in and Video of it firing. The video isn't the greatest quality so I may change it if I can get a better video recorded.The green glow is from the tracer round inside the hop unit. 








Slow Mo Video 



AEP tracer Video 


Any questions let me know. I will be working on an AEP pistol internal tracer unit I posted the info for this in my Cyma 030 / TM g18c upgrade thread. 

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I will update this one with a better video when i can find a better camera and the pistol im looking to do a internal tracer unit on the 18c aep so fingers crossed i can pull it off 

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  • 2 years later...

Hey there, looking to do this on a combat union hop which is made for 3mm uv leds, just wondering when you done this did you wire it to the motor posts or somewhere else as there was no photos and im in desperate need of figuring out a way to do this without using the motor posts as my grip barly allows for the current cables.

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  • 4 weeks later...
This thread is over three months old. Please be sure that your post is appropriate as it will revive this otherwise old (and possibly forgotten) topic.

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