laser body parts

[m3vuv]

Hi all ive just got one of these https://www.ebay.co.uk/itm/2w-blue-...45nm-450nm-blue-beam-laser-diode/163485498826
im driving using a 7805 v reg from 2 parellel 18650 cells,does anyone know of a driver that will supply 1400ma and fit in a laser pointer body,also where i can buy a suitable body collminating lense and body to build a laser pointer with it?,i found a driver on ebay thats 17mm dia but only 1 watt,ive a cnc mill ive built and want to use the laser for engraving etc,cheers Paul m3vuv.

 

[Immo1282]

I read your title as "laser body-parts", like laser eyes, laser arms and laser legs Thank god for context.

Firstly, a 7805 will NOT work well as a laser diode driver. Laser diodes must be driven with constant current drivers, not constant voltage drivers. If you use a constant voltage driver, the laser diode will quickly overheat and die as they have a negative temperature coefficient (i.e. as the temperature rises, the resistance drops allowing more current to flow, thus causing a further temperature rise).

Even if this was to safely drive a laser diode, your 7805 will not function with two parallel 18650 Cells as the dropout is around 2V - i.e. to output 5V constantly, you'd need a minimum input voltage of 7V - and from two parallel Li cells, you get 3.7-4.2V. If you want to build your own linear driver, use an LM317 configured in constant current mode (google schematics if you want).

So onto what you can/should actually use - If you search for Laser Diode Drivers, you will be able to buy very compact switching current-regulated DC-DC converters which are suitable for laser diode use. You can get these in many places, i.e. from SurvivalLaser or DTR's Laser Shop (in the US).

You should look to house your laser diode in a copper laser-module, which will give your laser diode a better way to lose waste heat and provide you threads to attach readily avaliable collimator lenses. If you use a 12mm Module, you'll have best compatibility with hosts you can buy.

For Hosts, talk to Lifetime17 on here, or look at the kits from SurvivalLaser. Alternatively, if you're handy with a lathe, you can machine your own There's plenty of resource on this forum and all you need to do is use the search box in the top right hand corner to find it!

Finally, if you're planning to stick around on the forum, post an Introduction thread, telling the forum roughly where you're located in the title, interests you have and what you want to get out of the forum. Also read the Sticky threads which outline a lot of FAQs that new members have.

 

[Mosc007]

Agreed using a 7805 is not a good choice.

But what he is doing is using the 7805 as a current regulator. It will only output 1 amp then drop back the voltage. Pretty crude but does give a 1 amp current regulator.

 

[Immo1282]

I hadn't thought of that - though it's still FAR from ideal, will waste a load of power and will be limited at the current-limit (so not adjustable, or 1.4A) built into whatever 7805 part that m3vuv is using.

OPs still better off with a dedicated switching laser driver in my opinion - it will be more efficient, and more fool proof...

 

[m3vuv]

exactly,the 7805 max out is 1 amp,i realy need 1400ma constant or 1800ma if i pwm it,i suppose i can regulate the voltage first using the 7805 ,then power a 317 as a constant current source from that,there is no way i could build it small enough to fit in a laser pointer body tho without using smd parts!. regards paul m3vuv.

 

[Immo1282]

i suppose i can regulate the voltage first using the 7805 ,then power a 317 as a constant current source from that

There'd be no need. Just the LM317 as a CC driver would be fine on it's own, No need for a current limit if your driver is regulating the current, as the current is set by the circuit feedback. The voltage will fluctuate if you change the current reference, and as the laser diode heats up but there is no problem with this.

there is no way i could build it small enough to fit in a laser pointer body tho without using smd parts!

There are a few inexpensive linear drivers as well as that are basically this, but on a compact PCB (usually 9x12mm or slightly longer). Alternatively, there are a few round driver boards that are often used directly as the battery contact, as all their components are on one side and there is room for a contact spring on the other. I've used some from a local UK supplier called OdicForce that have worked well for a 405 and 455 build for me. Not sure of your location so I don't know what local suppliers would be most convenient

 

[m3vuv]

imin the uk so ebay is realy my only option as shipping from the usa costs an arm and leg!.

 

[m3vuv]

i just looked there but dont see anyway to register on there.!

 

[Immo1282]

Oh nice Hi from Bristol! There are suppliers in the UK that aren't Ebay - but some of the best suppliers off that platform are in the US. Most forum members who machine hosts aren't here, and the favourites for Diodes, modules etc are all abroad too. As I mentioned, OdicForce does sell a few bits and pieces and doesn't charge more than a couple of quid for postage. I've gotten a couple of bits and pieces from RS/Farnell as well, but they're no good for diodes as they tend to charge through the teeth without a prohibitive MOQ.

One note, try to use the "edit" button to avoid double-posting. It reduces spammed notifications on the forum etc.

OdicForce's signup i believe is top/middle left of the page underneath where the basket is (if you click "sign in"). It should also prompt you to create an account at checkout.

 

[RedCowboy]

I thought you had parts for a Plymouth when I saw the title.

 

[m3vuv]

orded,cheers chaps