Disclaimer-I am not an expert! This is just information to point you in the right direction! Please thoroughly research everything you plan to use!
Pulse width Modulation
I think we've all done it before. Put huge coils in and cranked the power all the way up. Then we fire the device 3 or 4 times while inhaling, because if we don't, it would just be too hot, and if we turn down the wattage, we are waiting for the coils to heat up.
Well, that's exactly how a pwm circuit works!
Lets break down the term.
Pulse-a single vibration or short burst of sound, electric current, light, or other wave
Width-the measurement or extent of something from side to side
modulation- a regulating according to measure or proportion
So, lets go back to the fire button analogy.
The time between button presses is the pulse width, the act of pressing and releasing is a cycle.
If you press the button longer or shorter, or cycle your pulses slower or faster, you are modulating your pulse width.
A pwm pulses the coils for you, pure and simple.
This is not a DC to AC converter- AC(alternating current) Changes the flow of electrons in a push-pull fashion. There is only a push-stop pulsing with a pwm.
So lets look at a video showing these pwms at work, to get a better understanding.
So here we see the output of a pwm circuit. Notice how it differs from a converter. Either the power is on, or off. At no time is the power partially on. Converters take an input voltage and convert it to an output voltage. A pwm just changes how often the input voltage is applied.
Lets get these out of the way right now
My mod and build can handle 200w but I'm at 50% on my pwm so I'm vaping at 100watts right?
No, you are not. You are averaging 100 watts, but you are still vaping at 200watts.
This is a very important point to make, because vapers can hurt themselves with this mindset.
If 2 vapers side by side are vaping exactly the same setup, but one holds down the button for 5 seconds, and the other holds down the button for 1 second, is the one who held down the button for 1 second vaping at 1/5 the wattage of the one who held it down for 5 seconds? No, the same voltage and amperage were applied to the same coil, but the amount of time it was applied is different. This is exactly how a pwm works. By adjusting the amount of time power is applied to the coil, you can adjust how hot your coils will get in the end.
Now, here's where the danger factor comes into play. Some of us have gotten used to our dc to dc converters with adjustable output so much that they have chosen batteries that are safe within our normal vaping range. If our device goes up to 200 watts, but we never ever vape over 75 watts, we choose batteries with enough amperage to safely vape at that power level and get a bump in capacity in return. Since the power drawn from the batteries is less to produce a lower voltage output, neglecting all other factors, this is safe.
PWMS DON'T DO THAT! There is no voltage conversion in a pwm circuit, it only turns power on and off.
Make sure your battery can handle the maximum amount of power your build is going to draw!
You Are Vaping At Full Wattage, No Matter How You Adjust The Duty Cycle
My Voltage Meter Changes As I Move the Pot
Yes, it does. This is because it is showing the AVERAGE voltage, please refer back to the video above. Volt meters smooth out the readings, because of voltage fluctuations. If your power fluctuates in a circuit, your meter would just be a blur of changing numbers, especially if it was trying to display 8.4 volts and 0.0 volts over a hundred times a second.
The proper tool to display pwm circuit voltage is an oscilloscope, what is used in the video above
And in the video, we can see the power is at 10 volts, or zero volts. Adjusting the duty cycle only changes the average voltage.
I'm firing massive 10 wrap fused claptons at 5 volts!
This is the real beauty of the pwm setup. If you have one and are reading this, try putting that exact same build on a regulated mod and adjust the voltage to match your pwm reading. Notice the difference? You should. Is there magic or trickery in your pwm mod that makes 5 volts greater than it is in your regulated mod? No.
OHMS LAW IS THE LAW
Your coils heat up faster in your pwm that reads a ridiculous voltage because the volt meter is deceiving you.
But that is why people love pwms and swear by them, because they crank out a ton of power and eliminate almost any ramp up.
How does A PWM Work?
I will keep this very general, and link more detailed explanations and videos.
I will focus on the most common type in the vaping world, the 555 timer pwm.
Here's a very simple example of a pwm-not used for vaping.
The 555 timer measures time on and off by how long it takes to charge, and discharge capacitors. These capacitors are labeled c1 and c2 in the diagram. The combination of capacitor size, and the resistors that slow down the rate of charge of those capacitors, determines how long power is switched on, and how long the power stays off. Notice R1 has 3 connections. That is the potentiometer. By changing the rate at which Capacitor 2 charges and discharges, you change the duty cycle.
The 555 timer stays at the same duty cycle even though the voltage drops during use. Meaning the speed at which it switches will not slow down or spped up because the battery starts to get low. If you set it for 200hz, it'll stay that way until you adjust the potentiometer
The pwm circuit is a signal circuit. You do not connect the atty to the output pin of the timer. You need a mosfet to do the switching for you.
If you change the values of r1,r2,c1, or c2, you change how long the signal out stays on or off.
The umber of duty cycles per second, or frequency, can be measured in hz.
Thats the simple explination. Heres a whole bunch of links to learn more, with all the details.
555 Theory
Simple (and dirty) Pulse Width Modulation (PWM) With 555 Timer
The Pros
Minimal ramp up, but still control over power
Unlimited power capabilities, since it just signals an external switching device.
Cheap! seriously, the parts to make one are extremely affordable
Compact-depending on your skills and what you buy, they can become very small
The Cons
It's not variable voltage. Your battery will be at maximum draw no matter where you set the pot.
A full power spike at the lowest duty cycle might toast a coil if you decide to run a kanger subtank mini on a 3000 watt mod, but realistically, who would?
Power spikes can feed back through the mosfet and toast your 555 timer chip, so it's best to put those into a soldered socket, and keep a spare handy. There are also ways to reduce this risk, which will be covered in the mosfet section.
It's a lot of soldering! well, lets get to that right now
Premade Packages
If you feel that building a pwm from scratch is a lot of work, than you are in luck, because you have options.
Here's a few options I have found:
meet the Tiny PWM
For $9, and only 5 wires to solder, it's hard to go wrong. At 12.7*9.7mm, it even lives up to it's name. This one came from here:
Mod PCB Tiny PWM
here's another option
Found it here:
Ebay- Diyfancylights (ebay link does not work)
This one comes as a pre-soldered unit, or a kit, that has all the pieces you need, plus detailed instructions and a blank breadboard for those do it yourself that don't want the headache of soldering jumpers or calculationg the capacitor and resistor values.
Don't want to figure out that pesky mosfet?
Mosfet included smart pwmv2, found here:
Smart PWM V2.2
I do have one issue with this setup. I cannot find how many amps this mosfet can safely handle. That is a very important piece of information to have. So, if you do decide to use this chip, I BEG YOU to contact the manufacturer for more information.
Ok, so what if you don't want to have to solder a button, or volt display, or potentiometer, or shut off?
Well, here's as plug and play as I've found so far
Meet the NLPWM. digital potentiometer, fire button, remote switch options, dual mosfet, low voltage cut off, cruise control, power windows, etc. For $40 bucks, you can hook up 3 wires(positive, negative, and 510), And vape like a boss!
This setup is rated for a maximum current of 60 amps, and a 4s lipo. that comes to 1,008 watts at .28 ohms on a fully charged battery! I would never run it at it's max myself, I prefer to never run a component at more that 80% of it's capabilities. But, here's where I found it:
NLPWM
There are instructions and wiring diagrams on that page.
I hope this information answers some of the questions people have about pwms.
Please thoroughly research any product before you buy or use it!
This just shows what is available on the market, it does not review or test any of the claims made by the manufacturer.
Pulse width Modulation
I think we've all done it before. Put huge coils in and cranked the power all the way up. Then we fire the device 3 or 4 times while inhaling, because if we don't, it would just be too hot, and if we turn down the wattage, we are waiting for the coils to heat up.
Well, that's exactly how a pwm circuit works!
Lets break down the term.
Pulse-a single vibration or short burst of sound, electric current, light, or other wave
Width-the measurement or extent of something from side to side
modulation- a regulating according to measure or proportion
So, lets go back to the fire button analogy.
The time between button presses is the pulse width, the act of pressing and releasing is a cycle.
If you press the button longer or shorter, or cycle your pulses slower or faster, you are modulating your pulse width.
A pwm pulses the coils for you, pure and simple.
This is not a DC to AC converter- AC(alternating current) Changes the flow of electrons in a push-pull fashion. There is only a push-stop pulsing with a pwm.
So lets look at a video showing these pwms at work, to get a better understanding.
So here we see the output of a pwm circuit. Notice how it differs from a converter. Either the power is on, or off. At no time is the power partially on. Converters take an input voltage and convert it to an output voltage. A pwm just changes how often the input voltage is applied.
Lets get these out of the way right now
My mod and build can handle 200w but I'm at 50% on my pwm so I'm vaping at 100watts right?
No, you are not. You are averaging 100 watts, but you are still vaping at 200watts.
This is a very important point to make, because vapers can hurt themselves with this mindset.
If 2 vapers side by side are vaping exactly the same setup, but one holds down the button for 5 seconds, and the other holds down the button for 1 second, is the one who held down the button for 1 second vaping at 1/5 the wattage of the one who held it down for 5 seconds? No, the same voltage and amperage were applied to the same coil, but the amount of time it was applied is different. This is exactly how a pwm works. By adjusting the amount of time power is applied to the coil, you can adjust how hot your coils will get in the end.
Now, here's where the danger factor comes into play. Some of us have gotten used to our dc to dc converters with adjustable output so much that they have chosen batteries that are safe within our normal vaping range. If our device goes up to 200 watts, but we never ever vape over 75 watts, we choose batteries with enough amperage to safely vape at that power level and get a bump in capacity in return. Since the power drawn from the batteries is less to produce a lower voltage output, neglecting all other factors, this is safe.
PWMS DON'T DO THAT! There is no voltage conversion in a pwm circuit, it only turns power on and off.
Make sure your battery can handle the maximum amount of power your build is going to draw!
You Are Vaping At Full Wattage, No Matter How You Adjust The Duty Cycle
My Voltage Meter Changes As I Move the Pot
Yes, it does. This is because it is showing the AVERAGE voltage, please refer back to the video above. Volt meters smooth out the readings, because of voltage fluctuations. If your power fluctuates in a circuit, your meter would just be a blur of changing numbers, especially if it was trying to display 8.4 volts and 0.0 volts over a hundred times a second.
The proper tool to display pwm circuit voltage is an oscilloscope, what is used in the video above
And in the video, we can see the power is at 10 volts, or zero volts. Adjusting the duty cycle only changes the average voltage.
I'm firing massive 10 wrap fused claptons at 5 volts!
This is the real beauty of the pwm setup. If you have one and are reading this, try putting that exact same build on a regulated mod and adjust the voltage to match your pwm reading. Notice the difference? You should. Is there magic or trickery in your pwm mod that makes 5 volts greater than it is in your regulated mod? No.
OHMS LAW IS THE LAW
Your coils heat up faster in your pwm that reads a ridiculous voltage because the volt meter is deceiving you.
But that is why people love pwms and swear by them, because they crank out a ton of power and eliminate almost any ramp up.
How does A PWM Work?
I will keep this very general, and link more detailed explanations and videos.
I will focus on the most common type in the vaping world, the 555 timer pwm.
Here's a very simple example of a pwm-not used for vaping.
The 555 timer measures time on and off by how long it takes to charge, and discharge capacitors. These capacitors are labeled c1 and c2 in the diagram. The combination of capacitor size, and the resistors that slow down the rate of charge of those capacitors, determines how long power is switched on, and how long the power stays off. Notice R1 has 3 connections. That is the potentiometer. By changing the rate at which Capacitor 2 charges and discharges, you change the duty cycle.
The 555 timer stays at the same duty cycle even though the voltage drops during use. Meaning the speed at which it switches will not slow down or spped up because the battery starts to get low. If you set it for 200hz, it'll stay that way until you adjust the potentiometer
The pwm circuit is a signal circuit. You do not connect the atty to the output pin of the timer. You need a mosfet to do the switching for you.
If you change the values of r1,r2,c1, or c2, you change how long the signal out stays on or off.
The umber of duty cycles per second, or frequency, can be measured in hz.
Thats the simple explination. Heres a whole bunch of links to learn more, with all the details.
555 Theory
Simple (and dirty) Pulse Width Modulation (PWM) With 555 Timer
The Pros
Minimal ramp up, but still control over power
Unlimited power capabilities, since it just signals an external switching device.
Cheap! seriously, the parts to make one are extremely affordable
Compact-depending on your skills and what you buy, they can become very small
The Cons
It's not variable voltage. Your battery will be at maximum draw no matter where you set the pot.
A full power spike at the lowest duty cycle might toast a coil if you decide to run a kanger subtank mini on a 3000 watt mod, but realistically, who would?
Power spikes can feed back through the mosfet and toast your 555 timer chip, so it's best to put those into a soldered socket, and keep a spare handy. There are also ways to reduce this risk, which will be covered in the mosfet section.
It's a lot of soldering! well, lets get to that right now
Premade Packages
If you feel that building a pwm from scratch is a lot of work, than you are in luck, because you have options.
Here's a few options I have found:
meet the Tiny PWM
For $9, and only 5 wires to solder, it's hard to go wrong. At 12.7*9.7mm, it even lives up to it's name. This one came from here:
Mod PCB Tiny PWM
here's another option
Found it here:
Ebay- Diyfancylights (ebay link does not work)
This one comes as a pre-soldered unit, or a kit, that has all the pieces you need, plus detailed instructions and a blank breadboard for those do it yourself that don't want the headache of soldering jumpers or calculationg the capacitor and resistor values.
Don't want to figure out that pesky mosfet?
Mosfet included smart pwmv2, found here:
Smart PWM V2.2
I do have one issue with this setup. I cannot find how many amps this mosfet can safely handle. That is a very important piece of information to have. So, if you do decide to use this chip, I BEG YOU to contact the manufacturer for more information.
Ok, so what if you don't want to have to solder a button, or volt display, or potentiometer, or shut off?
Well, here's as plug and play as I've found so far
Meet the NLPWM. digital potentiometer, fire button, remote switch options, dual mosfet, low voltage cut off, cruise control, power windows, etc. For $40 bucks, you can hook up 3 wires(positive, negative, and 510), And vape like a boss!
This setup is rated for a maximum current of 60 amps, and a 4s lipo. that comes to 1,008 watts at .28 ohms on a fully charged battery! I would never run it at it's max myself, I prefer to never run a component at more that 80% of it's capabilities. But, here's where I found it:
NLPWM
There are instructions and wiring diagrams on that page.
I hope this information answers some of the questions people have about pwms.
Please thoroughly research any product before you buy or use it!
This just shows what is available on the market, it does not review or test any of the claims made by the manufacturer.
