Hi require a new laser for my saw anyone know where to get one thanks.

--
For full context, visit https://www.homeownershub.com/uk-diy...e-3117443-.htm

On 10/05/2021 19:45, Nick wrote:
Hi require a new laser for my saw anyone know where to get one thanks.


Circular, mitre, tile, reciprocating, see, eye or hand?

On 10/05/2021 19:45, Nick wrote:
Hi require a new laser for my saw anyone know where to get one thanks.

Google "laser for circular saw".

Nick wrote:
Hi require a new laser for my saw anyone know where to get one thanks.


https://changlong.en.made-in-china.c...Miter-Saw.html

It's a long walk to Chang Long.

In this example, you can see a grating sits on the
front and determines the output type. You could have
a dot (useless), or a line (useful).

https://www.amazon.ca/WANLIAN-Module.../dp/B0842HJVWF

Voltage: 3v-5v,Power:5mw === Nice, but not a full spec...

Another example, refuses to show us what is inside the barrel.

https://www.amazon.com/Lights88-Lase.../dp/B01N48M1VR

When you get them from a retailer in other parts
of the world, they come with more specs.

https://www.digikey.com/catalog/en/p...l-lasers/17847

635nm 2.7V ~ 5V 40mA 5mW Cylinder (12.5mm Dia) === Still not enough.

Here is a "datasheet". Still not enough.

https://www.quarton.com/download/21/
https://www.quarton.com/download/21/

*******

With a Japanese supplier you learn a lot more.

http://www.vinkarola.com/pdf/SanyoLDCatalogue2008.pdf

Devices operate off current flow, not applied voltage.
The applied voltage is a "side effect".

Three specs of interest.

Threshold current 50-70mA No light output when current is too low.
Operating current 230-260mA \____
Operating voltage 2.0-2.4V / Gives rated light output
Light output linear above 50mA
Current source, temperature compensated?
Or use current source, with closed-loop light monitoring.

One way to monitor lasers is with a "back facet monitor".
But these units have no back facet monitor, as that would
require more wires or contacts on the device.

To do a front monitor, requires a beam splitter and PD or PIN
up front. Then, the signal from that feeds the current regulator.
If laser intensity drops, the current regulator increases
current drive.

But we know an "appliance" such as a saw, it'll be just
a DC supply and a 10 ohm resistor in series, then the laser.
Because, they just don't care about the finer details :-)

You'll notice in the Sanyo listing, some devices have a PD
and that's the back facet monitor, for building a regulated
laser output. By using a PD, you don't monitor temperature.
As the laser gets warmer, the laser starts to extinguish, and
the PD tells the power supply to "turn up the current". The
power supply is only allowed to turn it up a little bit,
to avoid runaway behavior :-) If it gets hot enough, the laser
extinguishes and no amount of current brings it back. Temperature
is the "curse of lasers". One guy at work spent months trying
to find an innovative cooling solution for one of our
projects (you could see the poor guy "aging" while working on it).

The laser in yours, the barrel is at the same electrical potential
as the red wire. In laser modules with only one wire, it's the
black wire (ground). The barrel is (+) and the device still
needs a current source. When they give you a black and a red wire,
it means you don't need to make a flimsy solution electrically to
the barrel. But snipping a wire off it and using the barrel for (+),
why, that saved a whole penny! Whoopee.

This web page shows you how to build a current source (if, for
example, "bench testing" of the busted one). The idea of using
an LM317, is whether the input supply is 9V, 12V, 24V, the
LM317 in the example always puts out 125mA. If you increased
the resistor to 20 ohms, the current would drop to half that
or 62.5mA. I use these all the time for lighting projects,
as temporary supplies. Like when I sorted LEDs for a project,
and had 100 LEDs to measure, this was the kind of circuit
as used as a reference (at 11mA current flow level). Because
the application was going to work at 11mA, so I had to
reproduce the current flow while calibrating the project.

https://www.bristolwatch.com/ccs/LM317.htm

For your project, I would use a 6V supply with the LM317, to
give sufficient headroom for LM317 operation. (Giving 6V to
LM317, gives max 3V or so to the laser. That's a rough
idea of the compliance or max voltage of the current source.)

6VDC ---- LM317_cct --- (+) laser (-) ---- Ground

Or, you can use a resistor. Since no headroom needed,
voltage can be lower. This might be the cct in the saw.

5VDC ----- 22 ohm -------- 2.4V laser --- Ground 2.6V/22ohm = 118mA
Enough past threshold.

Resistors come with weird resistance values, and 22 ohms
is one of a set of "standard values". This sometimes
differs with power resistors. V^2/R = 2.6^2/22 = 0.3W,
Use 1/2 watt 22 ohm resistor. A 1/2 watt resistor is
not considered a power resistor. You can make a 1/2 watt
resistor out of a couple 1/4 watt ones.

---- R1 ------ R2 ----

1/4W 1/4W
11 ohms 11 ohms

And for God sake, be careful of your eyes!

There are plenty of lasers out there which are
not eyesafe. *Don't* be staring down the barrel
of these things. You will notice some of the better
datasheets give veiled warnings. That's because they
expect the professionals using these items, to
already know how harmful they are. Try to avoid pointing
the laser at metallic objects which may throw a
reflection of the laser, back at you.

HTH,
Paul