What do you do when you can’t find a max tracer unit for your hop?

[simonh]

Well you make your own!

 

[Rogerborg]

Oh, nice one. I've tracered up a couple of peasant hop units, but just with LEDs inset into them and a single resistor inline in the wiring, nothing that fancy.  Is that 2 LEDs per side?

[simonh]

2 leds per side, one set of UV one set of blue (UV light up red tracers better) two would probably have been fine but why take chances

 

I think I could do a neater job for the next one

[Sewdhull]

That's cool. What's the forward V on the LEDs, do you need resistors at all? 

[simonh]

I can’t recall offhand but I did the calcs and the resistors are needed, I tried a few variations and blew lots of leds in the testing

[Sewdhull]

ok, the UV leds i was looking at were I think, 3.5 fV so 4 of those, even 3 would be under or around battery voltage in series. Looks like yours are parallel tho so you'd need the current limiters.

LED drivers are cheap, so that's another possibility.

Edited May 12 by Sewdhull

[simonh]

3.2-3.8 fv - I am running them off a 9v battery, the resistors are really small IIRC, I bought them off bright components for pennies really and yes running parallel. One 9v lasts around 6 hours or so. 

[simonh]

V1 was a failure, far too bulky.

 

v2 is better.

[Pseudotectonic]

do these light up BBs better than tracer units? since this is a constant light

[simonh]

I’ve not yet tested this with bbs yet, my son has run a mad bull tracer hop for years and I never noticed the bbs out of that being any brighter than ones through my flash unit tracer.

 

this one is a lot brighter than the mad bull unit though so I guess we will see.

 

we can’t fit a tracer unit on this gun as it has an integrated silencer so one can’t be fitted.

[Sewdhull]

A slight aside, the Perun hybrid mosfet has power out put for such things as magazines and tracers.

 

Also I'd be tempted to connect the LEDs in series or parallel/series ( since you have 4 leds), you'd only need one resistor for limiting if any.

 

A project I'm interested in myself.

 

I notice that my UV torch makes for less bright tracers compared to pretty much all my white torches. Did you test the LEDs shining on a bb to gauge the effectiveness of the white or UV leds?

 

Sorry for all the input.

 

 

[Pseudotectonic]

Very tempted to do this, what wavelengths of an LED do I need for green and/or red tracer BBs?

 

My googlefu says I might need around 470 nm (a blue light) for charging red tracers assuming they are calcium sulfide based... but I am really not sure

 

Anyone know the correct numbers / absorption and emission spectra? And for green ones? In the UV range?

[Sewdhull]

365nm emitters are cheap and as UV as you need. White LEDs will do the same thing, which ironically are UV LEDs with a phosphor coating. Shine a torch on the bbs and you will see a wide range of light wavelengths will activate the phosphors. It will depend on what phosphor is used.

 

I do not think it matters about the tracer colour. Red is not as bright to our eyes as green at the same energy and phosphors favour the green...

[simonh]

All back together, not running any resistors for the moment, I can always add some in if it proves unreliable.

 

i know blue leds light up green BBs well, the UV ones are for red tracers, we generally run a mix of both just because… 

 

I have some white leds as well but the blue/UV mix just looks a bit cooler in the side of the gun.

The gun this is in is HPA so no mosfet required.

 

i do like to run a separate battery feed for the built in tracer mostly just because that is how we’ve always done it and you can choose to run the tracer or not.

[simonh]

 

 

 

 

[AttackBunny]

This is awesome, fair play for having a hand steady enough to solder something so small 😂 

is it just a case of battery input - resistors - LED  or more then that? 
thanks! 

[simonh]

there are online calculators that you put in the LED voltage, no of LEDs circuit type and battery supply and it will tell you what resistors you need.

 

I can assure you many many LEDs were destroyed in this process as I practiced!

[simonh]

It’s been out for its first game day today at Gaol, and while most of the gameplay ended up being outdoors, this did work brilliantly for the indoor sections.