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Please explain : DC to DC vs PWM

Xhalin

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I have some basic electronics (very basic only because of vaping lol)... But could somebody be kind enough to break down the difference for me? I have a couple of ipvs that can do this but have no idea of what the difference is.... Thanks in advance for your knowledge....
 

Jackson

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If you have that option, the only way you can go below your battery's voltage (step down) is by having it in PWM mode. With IPV/YiHi devices the PWM is only used when stepping down, as soon as your required voltage is above the battery's voltage (boosting) it will automatically switch to the flat DC-DC signal. In the straight DC-DC mode some lower volt settings will seem too hot/high.

Although it doesn't offer the option to choose, I believe the new iStick 50W uses the same combo approach.
 

rdsok

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PWM is pulse width modulation... it's one method of averaging the output of the PV by quickly pulsing the output. There are two methods to calculate what the output is... RMS is the default one that is almost like a DC output of the same value... then there is AVG or MEAN ( same thing, just a different term ) that calculates it off of the percentage of time the pulses happen which result on the lower settings being actually higher than what a DC output would actually be.

DC-DC is just a DC to DC power/voltage conversion used to either step up or down the output. Most of the cheaper mods/chipsets use a combination of PWM and DC-DC... using the PWM to perform the step down and then DC-DC for all other outputs above the voltage level of the battery. The higher end mods/chipsets use DC-DC for both step up and step down but they are less common at this time. Jackson was incorrect that all step downs are done with PWM... some are not.
 

Jackson

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Jackson was incorrect that all step downs are done with PWM... some are not.
I made no such blanket statement. I was responding to the OPs post concerning the IPVs that have the PWM choice option available.

I have a couple of ipvs that can do this
As I noted:
If you have that option,
 

lordmage

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DC - DC Direct current is applied to the circuit that includes the wiring and the device it is attached to. in a very basic sense mechanical mods do this the limiting factor is usually the power sources amp limit

PWM is pulse width modulation and in a very wide scale most of your vari voltage ego's and the like do this.
 

rdsok

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I made no such blanket statement. I was responding to the OPs post concerning the IPVs that have the PWM choice option available.


As I noted:

Sorry... the way it was worded... it sounded as if that was the only method for step down
 
Simplified : DC - DC means 3.7 Volts in... 3.7 Volts out.. PWM = 3.7 Volts in... 3 Volts out because the Pulse Width Modulation is pulsing the 3.7 Volts at a frequency that causes the other side to receive 3.0 Volts.
 

Xhalin

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Again all your knowledge is appreciated! Thanks to all who helped here!!!
 

Dissonance

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Again all your knowledge is appreciated! Thanks to all who helped here!!!

I notice very little difference between the two with the mods I use. DC signal is more flat and PWM gives greater power efficiency. Both the Provari and Evic use PWM and both are highly regarded APV's in the community. It's just that a small percentage of people are picky over the slightest detail. For most it's not an issue, just personal preference. Adjust your power to your sweet spot and keep it simple. All the best:)
 

rdsok

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I notice very little difference between the two with the mods I use. DC signal is more flat and PWM gives greater power efficiency. Both the Provari and Evic use PWM and both are highly regarded APV's in the community. It's just that a small percentage of people are picky over the slightest detail. For most it's not an issue, just personal preference. Adjust your power to your sweet spot and keep it simple. All the best:)

The output on the Provari's is still essentially flat with the additional filtering they do... can't say on the Evic... But looking at the opposite end of the PWM mod's like the Vamo... the output even when it's RMS is still a harsher vape at a specific setting than the same flat DC output would be. So this is as much about how well engineered the device is and it's output as anything.
 

Drone

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Like anything else, PWM can be done very well or it can be done badly. Like Dissonance said, there are some mods that do it very well like the Provari which is arguably the most accurate regulated vaping device on the market. And then there are others that don't do it so well. A lot has to do with the frequency of the pulses. For example the Provari 2.5 uses a pulse width frequency of 800 Hz, or 800 time per second which is fast enough to provide extremely smooth regulation. Many cheaper devices use 33hz, or 33 times per second which is noticeable while vaping and has a common label of rattlesnake vape. So nothing wrong with PWM, it just has to be done well.
 

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