How to drive laser with PWM ?

[bluewave65]

Hi,

i can`t find any resonable pwm driving solution for buildlog laser.
Only some half-way ideas ....

What do you suggest ?

M10/M11
E1P1 / E1P0
M3 / M5

I need controll beam power not only on/off system.

[wklaser]

PWM is for RF laser tube spec
and if for glass tube,this is useless

[twehr]

PWM is for RF laser tube spec
and if for glass tube,this is useless

I am not sure where you got this information, but I believe you may be confusing PWM with the laser's trigger frequency. RFs use specific frequencies, but glass tubes do not.

PWM (input) is the method that ALL current laser PS use to set the power level of the output. It ranges in % from 0 to 100. It is a 5v (usually 3.3v acceptable) DC signal that is modulated by turning it on and off so that it is on a certain % of the time. The PW then, receiving such signal, drives the laser tube to the corresponding % of power. (Not linear as most PS and tube combinations vary, but close enough for this discussion.) Nearly all modern controllers use PWM to control the power, regardless of whether using RF or Glass tubes.

If you are using a modern controller (DSP, etc), then the PWM signal is provided automatically. If you are building your own controller, then you can use an analog to pwm circuit (Hobard Designs in Australia is one that comes to mind).

All modern laser PS also accept an analog (0-5v) signal.

Tell us what the original poster really wants to do and how this question came up and we will be happy to help them figure it out.

Here is an article I posted about PWM and laser output. It does not deal with the electronics part but give you a base for understanding what it does and how your laser reacts to it.

[twehr]

Hi,

i can`t find any resonable pwm driving solution for buildlog laser.
Only some half-way ideas ....

What do you suggest ?

M10/M11
E1P1 / E1P0
M3 / M5

I need controll beam power not only on/off system.

The GCode you are showing is not for PWM, but for triggering the laser on and off. PWM sets the power level. See my explanation in response to the other post. Some of those with more GCode experience may be able to help you better with setting the PWM level from code.

[autocrib]

I have some problem, I need to boost a PWM signal at 5KHz and 450mV to 5V at 5KHz and 100mA
max. Could someone help me by providing list of the components that I need and a schematic to do this.

[bdring]

There are probably a lot of ways to raise the voltage, but such a high output current of 100mA rules a lot of the simple ones out. Are you sure you need 100mA? That is almost enough to drive a relay.

Fortunately, 5KHz is is pretty slow. I would probably use a simple transistor with the right saturation voltage.

[3dtech]

ou need to adjust your thinking; you cannot control both at the same time. The laser (and many other electrical devices) will show a voltage across itself as a function of the current passing through it. You could also say the current is a function of the applied voltage, but that's a poor way to actually control the laser as Sarge has noted.

A resistor does a decent job of limiting current. A constant-current regulator does a better - more precise - job. 3d printing mumbai pune - fdm technology
Sarge may correct me but I believe you could replace the comparator in his circuit with a single NPN transistor if you have enough signal to drive its base. The comparator gives you more flexibility.

[JenniferT]

What connections are you using?