DIY USB Passthrough - Lowering Voltage?

[nash076]

Hey all,

Love the forum. Built myself a USB passthrough as shown by bastage and several others. My only concern is the 5 volts it's drawing, a high considering the Li-On batteries put out around 3.6 volts. I'm concerned not only about running my atomizer that high, but also about my computer. I'd be happy to keep it around 4 - 4.2, if there was some way to limit the voltage intake . . .

I noticed UKUSA had a diagram including an LED in parallel in the circuit. Does this limit the voltage pulled out of the computer? Does it reduce the amount going to the atomizer? If not, is there another way to drop the voltage?

Thanks,
Nash

 

[nash076]

Seems I found my solution:

Placing a 1N4004 rectifier diode in series with the positive power lead off the USB to the atomizer dropped the voltage by a comfortable 0.8v. It's running around 4 volts now, not causing the computer to complain that I'm drawing too much power, and draws more or less like it does off the regular battery.

And I followed the diagram UKUSA (Ben, I believe?) came up with in another thread, running an LED in parallel to the main circuit. So now I have a nice indicator for when power is running through the unit, and it's within specs.

I might build a burn-off unit out of a N Coaxial DC jack and a 4.5 volt Radio Shack AC adapter as I saw someone had done in another thread, but for now I feel confident that I have a USB passthrough that won't damage my computer or my atomizer. I play it safe sometimes, what can I say . . .

Thanks,
Nash

 

[Fox3]

Gave my original 801 passthrough to my neighbor and put together another last night and did put a 1n4004 inline and it works quite well without getting the atomizer as hot as it does using the 5V direct from the port. Vape seems just as good to me.

A bit of fun to solder within the space available, but with a little care no real problem. Might have made more sense to put wire on the connector end and then heat shrunk over it. Hindsight is a wonderful thing .

Next we give one of the 510 manuals a go and see how that works out.

 

[Catanonia]

I run my atomizer at 5.1volts and it is much much better.

Just remember no more than 5 second presses on the switch.

It is also great for burning off crap from the coil of the atty and reviving old attys/ Done 2 myself with this.

 

[Sumratio]

Nice idea with the diode. I just burned out 2 of my EVO atties with my first mod and was trying to think of a solution. I think I was vaping for to long too, maybe 7secs or so.

 

[nash076]

Nice idea with the diode. I just burned out 2 of my EVO atties with my first mod and was trying to think of a solution. I think I was vaping for to long too, maybe 7secs or so.

To be fair, I think someone else came up with it before I stumbled onto it. Might have come up with it at different times, but someone else got to it first.

Nash

 

[ceo51378]

My battery mod I made runs off of about 5v and the atomizer has lasted almost 2 months now - it still vapes like it did the first day I used it. I think the gunk build up is reduced because it is burning it off more efficiently - so you should be fine with running 5volts. I know mad dog is running 6volts with no issues.

 

[Sumratio]

My battery mod I made runs off of about 5v and the atomizer has lasted almost 2 months now - it still vapes like it did the first day I used it. I think the gunk build up is reduced because it is burning it off more efficiently - so you should be fine with running 5volts. I know mad dog is running 6volts with no issues.

Not really sure because all I have is M401 atties but I think they are smaller and a little less robust than the 901 and 801. That really is just a deduction from the experiences i have read about since my knowledge is just with the Pilot and EVO. I tried a diode that was supposed to drop the voltage 1.6 volts but under no load it just dropped about .4 volts not worth risking another atty after burning the only 3 I had on me in one weekend ... needless to say I freaked when the 3rd blew. I thought I was safe using the computer USB port and taking short hits. I need to dig out my electronics books, feeling very rusty, it has been to long since I tinkered. I was thinking about whipping up a small circuit so I can use a small 50mA tactile switch and have voltage regultaion at 3.7V.

 

[kinabaloo]

Some models of atomizer can survive direct USB connection but many will overheat as the power does not drop under load as it does with batteries. If the atty runs noticeably too hot, it would be wise to make this change.

A silicon power diode will normally have a forward voltage drop of between 0.6v and 0.8v; but some versions have a voltage drop nearer 3.5v. If cannot measure, try 2 in series first (or check the datasheet).

 

[zachari]

What about putting a resistor inline?

 

[morphector]

you could do it with a resistor in series , it would have to be around 1 ohms 1watt....

that way you would get around 3.7v to the atomiser

 

[zachari]

you could do it with a resistor in series , it would have to be around 1 ohms 1watt....

that way you would get around 3.7v to the atomiser

Thanks a lot. Do you know how many amps an atomizer should draw? I guess it all gets down to what is the resistance of the atomizer when it is hot, this makes the rest of the math quick and easy.

 

[Sumratio]

I am an idiot ... I didn't see the voltage drop from the diode because I did not have a load on it. It was rated at 1.6 voltage drop at 1 amp so with an atty hooked up it dropped from 5.2 volts to a comfortable 3.7 volts. My 401s seem to draw right around 1 amp. Vapes real nice now without the burning taste and destroying atomizers.

 

[EldarKinSlayer]

Not really sure because all I have is M401 atties but I think they are smaller and a little less robust than the 901 and 801. That really is just a deduction from the experiences i have read about since my knowledge is just with the Pilot and EVO. I tried a diode that was supposed to drop the voltage 1.6 volts but under no load it just dropped about .4 volts not worth risking another atty after burning the only 3 I had on me in one weekend ... needless to say I freaked when the 3rd blew. I thought I was safe using the computer USB port and taking short hits. I need to dig out my electronics books, feeling very rusty, it has been to long since I tinkered. I was thinking about whipping up a small circuit so I can use a small 50mA tactile switch and have voltage regultaion at 3.7V.

Do you have more info on that diode, part number and where you got it would help me a lot. Thanx