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Dynamic PWM box
Dynamic PWM box
Dynamic PWM box
Dynamic PWM box
Dynamic PWM box

Dynamic PWM box

Endurance Lasers LLC
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Endurance presents a dynamic PWM box.

Allows changing laser power "on-fly" while you operate the laser.

A great tool for all CNC users.

Recommended for all Shark owners. 



Electrical features

Voltage supply :                                                             +12V  +-10%

Input current :                                                                 100mА +- 10%

Output amplitude :                                        0V- 5V +- 10%

Output current :                                                                             no more than 50mА

Output signal frequency (mode 1, 2):                    500 hz

Output signal frequency  (Mode 0):                       equals to the CNC controller signal frequency

PWM operational cycle (Mode 1, 2):                                     0-100% +-10%

PWM operational cycle (Mode 0):                          equals to the operational cycle of the CNC controller

Output signal amplitude ( input In1):                    0-24V +- 10%

Min voltage at In1 to activate the laser:                             1.5V +-10%

Input signal amplitude ( In2):                                  0-12V +-10%       

Min voltage at In2 to activate the laser:               3.5V +-10%

Input signal frequency at mode 0:                          up to 5Khz

Control and indication elements

Terminals 1-2(XT3) (PWM+ PWM-):                                      to the laser PWM + PWM-

Terminals 3-4(XT2) (In2+ In2-):                                 to the CNC controller PWM+ PWM-

Terminals 5-6(XT1) (In1+ In2-):                                 to the CNC controller PWM+ PWM-

SW1:                                                                                                   operation mode selection                         

Status LED:                                                                                       status indicator                                              

Duty cycle ADJ:                                                                               PWM duty cycle setting

Duty cycle:                                                                                        Duty cycle х10%

Power 12V:                                                                                       to the power supply 12V DC




Operation modes

The mode switch SW1 is used to select an operation mode. There are three operation modes:

Mode I : Manual setting of the laser power. The laser power is independent of the signals on connection terminals 3-4 or 5-6. The  Status LED indicator is on constantly. The Duty cycle ADJ switch sets the duty cycle mode from 0 to 100%.  The duty cycle value is controlled by the Duty cycle indicator. The indicator readings are multiplied by 10%. For example, if the indicator reads 2.10 it means that the PWM duty cycle is 21% ( 2.10 х 10% = 21%). This mode can be used for laser focusing if small values of the duty cycles are set (0.1 – 0.5).

Mode 0: Converting of the input signal at terminals 3-4 or 5-6 to the TTL 0-5V level. The Status LED indicator is on when there is a high signal level at terminals 3-4 or 5-6  (for more details go to the electrical characteristics part of this guidance). The Duty cycle ADJ switch and reading of the Duty cycle indicator have no influence on the device operation. If your CNC controller signal differs from the TTL, and for the laser operation you need a signal in the range of 0-5V, the output voltage of your CNC controller in this mode will be converted to the TTL level. For the correct operation of the device in this mode, the frequency of the output signal from your CNC controller must not exceed 5 Khz.   

Mode II: Dynamic laser adjustment. In this mode, it is possible to change the laser power during the CNC program running. The Status LED indicator is on when terminals 3-4 or 5-6 have a high-level signal  (for more details go the electrical characteristics  part of this guidance). Using the Duty cycle ADJ switch set a duty cycle from 0 to 100%. The value of the duty cycle are controlled with the Duty cycle indicator. The indicator readings should be multiplied  by 10%. For the correct operation of the device in this mode it is necessary that the CNC software (G-code) generates a signal with PWM duty cycle levels of 0% or 100%.  Any other PWM duty cycle levels will lead to an incorrect operation of the device.

How to connect the device

Let's use a Shark CNC as an example to connect the device to. The G-code should be generated in such a way that the laser could run at 100% at any workplace and the Duty cycle ADJ potentiometer could change the laser power during the CNC Shark operation.  For work we use Mode II.

If you need to convert the output signal level of your CNC controller to TTL (Mode 0) or to change the laser power during the operation (Mode II), or to turn on the laser and adjust its power without connection to the computer and usage of a special software(Mode I), connect the regulator according to the general connection scheme. Select a necessary mode with the SW1, Duty cycle ADJ and control the duty cycle on the Duty cycle display.


Technical implementation

The PWM signal adjustment device is assembled on the basis of a Microchip PIC12F683 controller.

To provide the operation of modes I, 0, II, a hardware timer, a comparator and an analog-to-digital converter of the controller are used. This increases the speed and accuracy of signal processing by the controller. The PWM signal adjustment device is protected against incorrect polarity of the supplied signals and 12V supply.




To prevent damaging of the device, CNC controller or the laser don't exceed the values given in the electrical charactristics part of this guidance by more than 20%.

Laser radiation is hazardous to eyesight, so wear safety goggles when running a laser.   Use the laser in a well-ventilated room with forced air ventilation to prevent possible poisoning during the combustion of various materials when laser cutting or engraving.


Mode 1 - 100% signal from the controller; turn the knob; change the power as needed.
Mode 0 - Off
Mode 2 - This is the manual mode (we adjust the power with the handle) as on the stand. There is nothing to enter at the entrance.

The wires that are marked IN are connected to the CNC controller.
Wires that connect OUT to a TTL laser




Engraving on PLA plastics with dynamic PWM box


Laser bonding using a DPSS 10 watt laser and a dynamic PWM box.



PCB design and the schematic