Considering a DX laser for a special project

[mw1111]

hi all like the title says im considering getting a laser from DX to play around with, and i have a somewhat ingenious way to power it (at least i think so lol )

http://www.dealextreme.com/details.dx/sku.10095

anyways, thats a 100mW laser that already has a driver and a very large finned heatsink, for 20$ there. what interests me very much is the fact that it needs an input of 5V, so if i get this i plan to hook it up via USB to my computer, do you guys think it would work? i have a 28' USB cord just dying to be modded into a power cord, what do you guys think?

 

[Chris.]

Should work as long as the New Wish unit doesn't need more than 2.5W.(5v @ 500mA max for USB 2)
Good luck!

 

[mw1111]

i doubt it needs more then 500mA to work, but that does pose a possible problem doesnt it? (alliteration aside lol)

 

[Chris.]

Ha
http://www.girr.org/mac_stuff/usb_stuff.html
Having looked at that, particularly the "Xantrex XPower Pocket Inverter" @ 110 VAC at 80 watts I'd say you shouldn't have a problem!
Were you considering some sort of control via USB or just power?
In Maplins(UK store) they sell a USB programming kit http://www.maplin.co.uk/Module.aspx?TabID=1&ModuleNo=42857&doy=1m12
Which might give some sort of control for effects?

PS: I notice that under 'high load' the voltage drops to ~ 4.6v which might be a problem..

 

[mw1111]

hmm if all else fails im sure this laser will only put out a bit less if the voltage sags, and no im not looking to get any control, ill actually be taking the two information pins out so they cannot interfere

 

[chimo]

You may want to check out my mini-review in the reviews section on this laser.

 

[Chris.]

If all else fails, just wire 2 USB ports in series (10v) into DDL's circuit, guaranteed to work

 

[mw1111]

chimo you actually have this laser? hmm interesting ill brb lol

EDIT: well interestingly enough the laser looks even more appealing to me now, its so cheap but it works, i guess you cant beat that!

 

[mw1111]

If all else fails, just wire 2 USB ports in series (10v) into DDL's circuit, guaranteed to work

lol and i just happen to have a psu made by daedal, unfortunetely its about to be soldered to a GB diode by Kenom

 

[positron]

If all else fails, just wire 2 USB ports in series (10v) into DDL's circuit, guaranteed to work

I would check into this a bit before doing it. I would think that if you connected the positive of one usb port to the ground of another, you would have a short circuit that could possibly damage your motherboard.

Another point is that I think from memory that the USB spec only guarantees 200mA or so from the usb port unless your device requests more power. Different motherboards may supply more though but its not guaranteed.

edit: added second point.

 

[Benm]

Positron is right, you cannot connect 2 usb ports from a single computer in series. You'd short one out by connecting the positive of one to the (shared) negative of another.

Also, on current: USB ports -can- provide 500 mA at most times, but this requires that you request this current from the PC by an actual usb device. Just hooking a power cable to positive and negative will normally give you only 100 mA, and isn't even required to give you more than 50.

 

[Chris.]

I have an external laptop hardrive that does JUST that, 2 usb plugs into one wire...

Likely in parallel though for ~ 1A.

 

[mw1111]

yes i doubt it directly wires them together, but instead actually uses the bandwidth of both wires to double its speed?

 

[Benm]

Such setups are usually done for power alone. It will register as a 500 mA device on both ports and as a mass storage device on one of them.

 

[mullerhawk]

I have the same laser. I tried it with a Nokia phone charger rated at 320mah and it did not burn anything. But when i changed to a newer Nokia charger rated at 880mah magic started to happen! So i dought the USB port can supply that kind of juice!

 

[mw1111]

'magic started to happen' like how much magic exactly? is the beam bright, can it light stuff within a second or two, does it feel burning to the skin, stuff like that?