When 5V really isn't 5V

[a2dcovert]

I have been wondering why the Prodigy was definately hitting harder than my pass through. They are both supposed to be 5V devices. I got to thinking that maybe this wasn't the case. We've already seen Steve's demonstration of the actual voltage of the Prodigy with 2 X 3.2 volt and the resister.

I decided to test my pass through to see what the actual voltage is at the atomizer under load. I was surprised to find 3.7V to 3.8V even though it was supposed to be supplied by a regulated 5V power source. I tested it connected to my PC and to a Kensington power pack. I tested both power sources and they both put out 5.01 to 5.02 volts unloaded.

So my question has been answered.

I also tested my nicostick for the same conditions. With one 14500 900 mAh battery the unloaded voltage was 4.10v and the loaded reading was 3.68v.

Don't consider all these readings to be precise because the volt meter i'm using is not deamed a precision instrument. But the readings are accurate enough to make the point.

This should answer others questions too.

Kevin

 

[markarich159]

So, basically, the 6ft 20gauge wire on the USBPass offers more resistance then the actual resistored switch on the Prodigy V1?

 

[Nuck]

The current from a USB is very low (0.5a). The voltage is a function of the current so you see a large drop. It has nothing to do with resistance as the resistance of wire is extremely low and will not affect the output.

 

[a2dcovert]

So, basically, the 6ft 20gauge wire on the USBPass offers more resistance then the actual resistored switch on the Prodigy V1?

I'm sorry if I misled you, my passthrough is not the PS PT. I wired a USB 2.0 cable directly to the momentary switch and connector on a nicostick without a battery.

The current from a USB is very low (0.5a). The voltage is a function of the current so you see a large drop. It has nothing to do with resistance as the resistance of wire is extremely low and will not affect the output.

Nuck the USB port is capable of much higher current than that. USB adapters I have tried including a 0.5 amp ac adapter and a 1 amp ac adapter won't even fire the atty. Besides the Kensington is capable of 1.5 amps. The wiring in the USB cable approximately 28 guage.

The importance of this info is simply, I thought my PT was equal to the Prodigy. I have proved that it isn't.

Kevin

 

[VapingMike]

The current from a USB is very low (0.5a). The voltage is a function of the current so you see a large drop. It has nothing to do with resistance as the resistance of wire is extremely low and will not affect the output.

While I know you are correct for the PC's USB ports, I thought one of the major advantages of using a power pack is that you can draw 1.0 amp or more, instead of being limited to 500 mA. I might be wrong, as I don't own one of these, though.

 

[a2dcovert]

While I know you are correct for the PC's USB ports, I thought one of the major advantages of using a power pack is that you can draw 1.0 amp or more, instead of being limited to 500 mA. I might be wrong, as I don't own one of these, though.

You are correct. The Kensington is rated at 1.5 amps.

Kevin

 

[Robert]

Have you put the meter on the PS with the 5v switch- and see what it reads?

Do you know what kind of a resistor they use?

 

[VapingMike]

The current from a USB is very low (0.5a). The voltage is a function of the current so you see a large drop. It has nothing to do with resistance as the resistance of wire is extremely low and will not affect the output.

While I know you are correct for the PC's USB ports, I thought one of the major advantages of using a power pack is that you can draw 1.0 amp or more, instead of being limited to 500 mA. I might be wrong, as I don't own one of these, though.

 

[VapingMike]

Sorry - accidently hit "post" twice. I want one of those Kingsenton power packs if they are rated at 1.5 amps!

 

[Liscab]

To my Knowledge a pt receives 5 volt but its output to the atmy should be 3,7 or less, my atmys work better on batteries.I don't know why most people state that a pt supplies 5 volts

 

[a2dcovert]

Have you put the meter on the PS with the 5v switch- and see what it reads?

Do you know what kind of a resistor they use?

Here is the data Steve posted on the PS PT:

PS USBpass PT (20g Wire -- 6ft) <-- Standard USBpass From PureSmoker
At Atomizer -- 5.07v
Under Load (True Voltage) -- 4.28v

As far as I know he doesn't use a resistor in his PT.

Kevin

 

[Robert]

I want to know what resistor is used in the 5volt prodigy switch

 

[ChefChris]

As far as I know he doesn't use a resistor in his PT.

Kevin

Check out this thread: Prodigy PT vs <every other passthrough>

To quote Steve:

"Yes, the PureSmoker USB Passthrough utilizes direct USB power -- No inline regulator/chip or battery. Meaning, you plug the PT in, grab a multimeter, and you will see 5.07v at the end Hope that helps bud!"

 

[a2dcovert]

The current from a USB is very low (0.5a). The voltage is a function of the current so you see a large drop. It has nothing to do with resistance as the resistance of wire is extremely low and will not affect the output.

Here is the data on USB 2.0 Nuck:

In Battery Charging Specification, new powering modes are added to the USB specification. A host or hub charger can supply maximum 1.5 A when communicating at low-speed or full-speed, maximum 900 mA when communicating at hi-speed, no upper current limit when no communication is taking place.

Taken from wikipedia. Took me forever to find that data.

Kevin

 

[VapingMike]

I want to know what resistor is used in the 5volt prodigy switch

It's a 2 watt 1/2 Ohm resistor

 

[ChefChris]

Have you put the meter on the PS with the 5v switch- and see what it reads?

Do you know what kind of a resistor they use?

I think what you're referring to is Prodigy with the 5v switch since the passthrough doesn't have different switches.
a2dcovert seemed to think you were talking about the PT...

Anyway, In that case, I'll take a reading from mine right now with *reasonably* well charged batteries...

I get 6.60 volts without the atomizer attached. It should be a heck of a lot closer to the 4.7-5.5ish range when actually in use, depending on how well charged the batts are.

 

[a2dcovert]

To my Knowledge a pt receives 5 volt but its output to the atmy should be 3,7 or less, my atmys work better on batteries.I don't know why most people state that a pt supplies 5 volts

Here is the post where Steve supplies the info. No need to guess.

http://www.e-cigarette-forum.com/fo...-device-under-load-prodigy-other-devices.html

Kevin

 

[Robert]

if they run 3.0 volt x 4 = 12volt and you want 5

Then 12/x (resistance needed) = 5 (volts wanted)/ 1 so
12/x=5/1
5x=12
12/5=x
x=2.4
resistor is 2.4 ohms

or if they use 3.0 volts x 4 and run 2 and 2 in paralell then you would put a 6 in place of the 12 I'm not sure exactly how there doing it?

I wanted to know exactly which resistor is used if any one knew.

 

[HaploVoss]

I can see low amperage, but I cannot see how you would be getting less than ~5 volts from a USB port without some sort of resistance or regulator. Is it possible you have several devices in use and you have a maxed out power supply, running this off of a computer? Even in this case, there would have to be an issue with the internals of the board (which I have seen before in a few cases when the board is under heavy load with an underpowered power supply).

Have you tried checking the output of your passthrough attached to say a USB power supply? (I mean like a wall adapter)

Take care,
- Hap

 

[a2dcovert]

I can see low amperage, but I cannot see how you would be getting less than ~5 volts from a USB port without some sort of resistance or regulator. Is it possible you have several devices in use and you have a maxed out power supply, running this off of a computer? Even in this case, there would have to be an issue with the internals of the board (which I have seen before in a few cases when the board is under heavy load with an underpowered power supply).

Have you tried checking the output of your passthrough attached to say a USB power supply? (I mean like a wall adapter)

Take care,
- Hap

If you were addressing my comments you missed the entire point I was making. Originally my assumption was the same as yours, that the 5v output would be present at the atty. That wasn't the case in my test. Is the voltage drop because of some resistance in my circuit, that is entirely possible.

I don't have an AC to USB power adapted powerful enough to use in a test. The PT trips the 1 amp adapter I have. I connected the USB port on my laptop, the laptop docking station, and a 1800 mAh 5v battery.


Kevin