Designed by Mark Mathis, the Smart PWM V2 is a variable voltage board for use with personal vaporisers. It switches an N channel MOSFET, uses an analog potentiometer to adjust the duty cycle up/down, utilises an LED indicator and a momentary on switch to fire the device as well as perform other functions such as locking the voltage, locking the buttons, selecting regulated mode and setting the low voltage cut off.
It works in a similar way to 555 timer PWM mods, but has some very useful features such as lock/unlock, fire timeout, low voltage cutoff and a “regulated” mode to provide a consistent vape through the life of the batteries and remembers these settings even if you swap batteries.
Input Voltage: 2s-3s(13v max)
Output voltage: Adjustable between 0-100% loaded battery voltage
Idle current: 6ma(board by itself) typical
Voltage measurement accuracy: 2.2% typical
Switching frequency: 62hz
Reverse polarity protection: No
Pot value = 1k+(Any value 1k+)
LED pin current: Limit to ~10ma
The Smart PWM board can be used with 2s to 3s input. The microcontroller automatically detects the input voltage and will change settings according to the input voltage.
The Smart PWM board can lock to prevent the mod from accidental firing. Pressing the fire switch 3 times within 1 second will lock/unlock the mod. Lock/Unlock will be indicated by the LED flashing 4 times.
When unlocked, the mod will go into lock mode when it is fired for longer than 10 seconds. It can be unlocked by pressing the fire switch 3 times within 1 second.
By defauly, the Smart PWM board is in unregulated mode. It can be used just like any 555 timer mod. You can adjust the duty cycle up and down with the pot, but as your battery dies the output voltage will also decrease. To achieve a consistent output voltage, the board utilises a regulated more. After being set, the board will automatically adjust the duty cycle up as it needs to so it can maintain the output voltage that was set. It also keeps the setting after you swap your batteries.
Once you have your vape dialed in, you can set your desired output voltage by locking the mod and holding the fire switch for 3.5 seconds. The regulated mode setting will be saved and indicated by the LED blinking 3 times quickly. Keep in mind that if you set the desired output voltage too high and your loaded battery voltage goes below that the mod will fire at max.
To turn regulated mode off, follow the same procedure. The LED will blink 1 time quickly to indicate regulated mode is off.
LOW VOLTAGE ADJUST
It's always a good idea to monitor your own batteries, but the Smart PWM V2 can cut off if the voltage gets too low. The LED will blink 7 times letting you know your battery voltage is too low when you try to fire the mod. Since the recommended cutoff voltages differ for LiOn and LiPo cells, the Smart PWM board utilises a different low voltage cutoff mode for each. By default, the board is set to LiOn cutoff voltages, but the setting can be changed easily and only needs to be set once. See "How to change the low voltage cutoff mode".
The cutoff voltages are as follows
2s LiOn: 6.6v unloaded
3s LiOn: 8.25v loaded
3s LiOn: 9.6v unloaded
2s LiPo: 6.6v loaded
2s LiPo: 7.2v unloaded
3s LiPo: 9.9v loaded
3s LiPo: 10.8v unloaded
HOW TO change the low voltage cutoff mode:
By default, the low voltage cutoff is set to LiOn mods (18650). To change the low voltage cutoff mods, lock the mod by pressing the fire switch 3 times within 1 second.
Turn the pot to 0%
Hold the fire switch for 3.5 seconds.
The LED will blink slowly 2 times indicating the low voltage cutoff mode is LiPo.
Unplug the batteries and plug them back in.
The mod is now in LiPo low voltage cutoff mode.
This setting only needs to be set once.
Follow the same procedure if you need to change the low voltage cutoff settings back to LiOn mode.
The LED will blink slowly 1 time indicating the low voltage cutoff mode is LiOn.
Support and other questions
Mark the designer of the Smart PWM boards takes customer support very seriously and has set up a friendly facebook group to offer support and guidance and provide further resources such as instructional videos, the most up to date wiring schematics and troubleshooting. The Smart PWM facebook group can be found here