Output question on my new DIY Dorcy Jr.

Hello, I just finished my first DIY Dorcy Jr. and have a few questions about it. This Dorcy is running off of the original driver with just a 5.1ohm 1watt resistor. The diode is a 16x 650nm. There is a custom heatsink in there thanks to Dark Horse  . If anyone is considering buying from him please do he is fast and does quality work. Anyways, I was wondering why its not possible for me to pop balloons or light matches. The beam also doesnt seem to be that visible unless you look at it from a certain angle and the dot flickers sometimes when I turn it on. My question is how can I push this thing to the limit but still have quite a bit of diode life. I mean would throwing in a diff resistor (if so what size is recommended or am I in the sweet spot) be better or would the adjustable FlexDrive by lava help me in this situation. Im not sure if that FlexDrive can push this thing past where it is now so if anyone knows please let me know. The dot doesnt seem to stay tight from a distance even after focusing it. This is my first Dorcy so im kind of not sure what to expect from it. I know this is nothing special and has been done a million times and everyone has one or has done on in the past but I threw a few pics in just for the heck of it

hey Charlie,

looks like a nice build. and it could be a number of things on why it can't pop balloons or light matches. first, what color balloons are you using? I've found dark blue balloons work the best as they need to absorb the red light for it to be effective. and make sure to focus the laser to as small of a dot as possible on the surface of the balloon. it should pop pretty instantly..

and for matches, it's probably the same problem of reflected light. try using a sharpie and coloring the tip black / blue and letting the ink dry then try again.

a 5.1 ohm should be fine for this application, if nothing above works you can check the current going to the diode with a multimeter if you have one to let you know more. somewhere between 250-300mA should be good if its one of my laser diodes, if it's senkats, then 300-350mA would be probably better as they are a little stronger.

you shouldn't really need a flexdrive for this, the driver in the Dorcy is usually very good for high power reds.

let us know how it works out.

good luck,
kendall

CharlieMurphi said:

Hello, I just finished my first DIY Dorcy Jr. and have a few questions about it. This Dorcy is running off of the original driver with just a 5.1ohm 1watt resistor. The diode is a 16x 650nm. There is a custom heatsink in there thanks to Dark Horse  . If anyone is considering buying from him please do he is fast and does quality work. Anyways, I was wondering why its not possible for me to pop balloons or light matches. The beam also doesnt seem to be that visible unless you look at it from a certain angle and the dot flickers sometimes when I turn it on. My question is how can I push this thing to the limit but still have quite a bit of diode life. I mean would throwing in a diff resistor (if so what size is recommended or am I in the sweet spot) be better or would the adjustable FlexDrive by lava help me in this situation. Im not sure if that FlexDrive can push this thing past where it is now so if anyone knows please let me know. The dot doesnt seem to stay tight from a distance even after focusing it. This is my first Dorcy so im kind of not sure what to expect from it. I know this is nothing special and has been done a million times and everyone has one or has done on in the past but I threw a few pics in just for the heck of it

Click to expand...

You should be able to go down to a 2-ohm resistor and still be just fine.

Question -- Are you focusing the beam down? Sorry if that seems like a dumb thing to ask... but I've had to tell people that that actually is necessary...

Thanks for the reply. As for the tightness of the dot at a distance .... Im not sure what to be expecting but the dot doesnt really stay together all that well. Is that normal? Also, if i were to use a Senkat diode about what resistance should be used (estimate). I am smart enough to realize that the focus should be adjusted..yes . You really think I can get away with using a 2 ohm resistor :-?

Thanks

CharlieMurphi said:

Thanks for the reply. As for the tightness of the dot at a distance .... Im not sure what to be expecting but the dot doesnt really stay together all that well. Is that normal? Also, if i were to use a Senkat diode about what resistance should be used (estimate). I am smart enough to realize that the focus should be adjusted..yes . You really think I can get away with using a 2 ohm resistor :-?

Thanks

Click to expand...

The dot should "focus" at whatever distance you want. It becomes harder to focus at a distance because you can't see it as well. At a distance it helps to have someone down at the target to help you get it focused. Also, the farther the distance, the more your hand shaking will effect the energy absorbed. At a distance you really need to have a stand of some sort to hold the laser.

Peace,
dave

CharlieMurphi said:

As for the tightness of the dot at a distance .... Im not sure what to be expecting but the dot doesnt really stay together all that well. Is that normal?

Click to expand...

Focus the dot to be as small as possible at the distance that you want it to be most powerful, so you're trying to pop a balloon 5 ft away, make the dot super tiny at 5ft away so get the most power out of it at that range. when you have it focused at that range it will be a larger dot shorter & further away which is normal, you're only concerned with the size at 5ft.


and no,
don't use a 2 ohm, that's just asking for a dead diode.

try a 3.7-4.7 or something in that range. I've used a 3.3 ohm for a long open can to make it run pretty hot, measured upwards of 420mA.

Ok sounds good, i'll try that. When you refer to these resistors you are talking about 1watt correct? Not 1/4 or 1/2 watt? I am using the heatsink in this so I want to be able to have as much power and as much life as possible with a 1-2 min on and 30 seconds off cycle. Thanks again for the help.

CharlieMurphi said:

Ok sounds good, i'll try that. When you refer to these resistors you are talking about 1watt correct? Not 1/4 or 1/2 watt? I am using the heatsink in this so I want to be able to have as much power and as much life as possible with a 1-2 min on and 30 seconds off cycle. Thanks again for the help.

Click to expand...

I use 1/8 watt resistors in all of mine, just because of the size. they work quite well.

As far as asking for a dead diode with a 2-ohm resistor... not really. I've had one going for weeks on a 1-ohm, and it's doing just fine. and this is with a good hour of runtime every day.

Chad said:

[quote author=CharlieMurphi link=1214880821/0#6 date=1215035720]Ok sounds good, i'll try that. When you refer to these resistors you are talking about 1watt correct? Not 1/4 or 1/2 watt? I am using the heatsink in this so I want to be able to have as much power and as much life as possible with a 1-2 min on and 30 seconds off cycle. Thanks again for the help.

Click to expand...

I use 1/8 watt resistors in all of mine, just because of the size. they work quite well.

As far as asking for a dead diode with a 2-ohm resistor... not really. I've had one going for weeks on a 1-ohm, and it's doing just fine. and this is with a good hour of runtime every day.  [/quote]

ah crazy. maybe had something to do with your 1/8 watt resistor I'm thinking... only allowing 125mW (1/8 W) through to your diode (I think that's how that measurement works? not positive on this tho)

and 1watt, 1/2 & 1/4 are good. I'd stick with the 1 watt or 1/2 watt to allow the max amount of power through it.

I'm not positive either... but heck, it's running at 180mWs+ constantly, so I'm not complaining.

Sounds good, I got the focus issued solved and can now burn things within range. I still am not sure if its normal that the beam isnt really that tight at a distance even after focusing it.

CharlieMurphi said:

Sounds good, I got the focus issued solved and can now burn things within range. I still am not sure if its normal that the beam isnt really that tight at a distance even after focusing it.

Click to expand...

Nice build! ;D Glad to hear you are getting it dialed in.
I would stick with the 5-ohm resistor when using a 16x, unless you are willing to be replacing it soon, possibly. I use 1/2 watt rated resistors, 1-watt would be the ideal, but they are pretty big.
Regarding focus, at very short distances, you can focus to a very tight dot, with a blu-ray, you can focus to an even tighter dot, but as distance increases you have divergance working against you, (you can expect at least 1mm/meter-1mRad). After about 10', you simply will not be able to focus your dot to less than 4-5mm. With a 130mWish beam, spread out over 4-5mm at the tightest, things are going to be "limited". If you use an open-can diode, and reduced the resistors to 1-2ohm, or eliminate them all together, you will be able increase your power at a distance, but the dot will not focus any tighter without better or more elaborate optics, such as a better collimating lense, or using a "beam-expander", (try shooting your laser through a telescope/binoclular). Beam-expanders consume some of your power, more expensive ones consume less and focus tighter, but in the end, if you want more power, you will need more power.
I side-stepped this issue with just building ever increasingly more powerfull lasers, (read-addiction)
The beam of a 650nM laser is not really all that bright, just a dark color, I am not sure if yours is "bright enough" or not, but it should be if you are burning things. The greens are way brighter, even a 5mW.
Congratulations on the project! ;D
DH