I need DIY passthrough advice, STAT

[interestingfellow]

DIY Pt, no problem, right? well......

My riva batts are dying but still usable, and I have a 5 hour drive on saturday. They won't make the cut (I'll end up having to wait for the batteries to charge in order to keep vaping*.

So I need to build a DIY Pt, and need some help with the 3.7v portion.

I'm gonna build a Pt with no battery, 3amp switch, 510 fitting, and a cord w/usb plug. i know 2 amps is needed, and I think I have a car adapter that'll do that. But I need 3.7v because all I have are 2ohm boges.

So, what's the best way to go from 5v to 3.7v. I was thinking of a LM317T from the radio crack. Dunno, but whatever it is I do, I gotta do it by Friday night (7/8/11).

Any help would be greatly appriciated!

I have already ordered the parts to build my next ecig mod, but don't have time to wait on shipping on a Pt, so I have to mcguiver it NOW.

 

[bstedh]

That may not be able to handle the amps of the atty as it states 1.5A but as you will be using the lower end voltage you might be good. Otherwise bring a usb 12V adapter and keep one on the charger while using the other. Look to see if Rat Shak has a 3.7V or close fixed regulator as you don't need to worry about efficiency. You may need to put a heat sync on it however.

 

[Java_Az]

The LM317T has a max of 1.5 amps so it might just go into protection mode while vaping. 3.7 volts with a 2ohm atomizer = 1.85 amps. Maybe with a big ... heat sink it will be ok. Other then that there is a PWM circuit in the battery section on the mod forum that you can build with Ratshack parts, might be worth looking at.

 

[interestingfellow]

I've got to220 5v & 12v + & - regulators laying around, as well as heatsinks. I'll look again, but I don't think the crackshack has 3.7v..... looked again;they ain't got'm online.

What about just chucking a resistor in there? all i've got lying around are 1/4 watt size though.

 

[bstedh]

I've got to220 5v & 12v + & - regulators laying around, as well as heatsinks. I'll look again, but I don't think the crackshack has 3.7v..... looked again;they ain't got'm online.

What about just chucking a resistor in there? all i've got lying around are 1/4 watt size though.

Go with a couple of high wattage diodes over resistors. They are smaller and handle more power.

 

[bstedh]

You can get just about everything you need to build a PUCK at RS.... This might be the option to look into.

 

[Java_Az]

I've got to220 5v & 12v + & - regulators laying around, as well as heatsinks. I'll look again, but I don't think the crackshack has 3.7v..... looked again;they ain't got'm online.

What about just chucking a resistor in there? all i've got lying around are 1/4 watt size though.

You would need a 10 watt resistor of higher or else it would just fry. Diodes can work but your a slave to the voltage drop of the diode So you might not get as close as you like to 3.7 volts. Two or Three in series should get you kinda close to the ballpark.

 

[Dalton63841]

Go with a couple of high wattage diodes over resistors. They are smaller and handle more power.

Exactly what I was thinking. 1 diode would bring it down to ~4.3v. 2 in series would be 3.6v...

 

[interestingfellow]

You can get just about everything you need to build a PUCK at RS.... This might be the option to look into.

Ok, I googled it first. DO you have a link to said puck?

 

[bstedh]

http://www.e-cigarette-forum.com/forum/battery-mods/105465-now-puck-cheap-parts-easy.html

 

[Stosh]

http://www.e-cigarette-forum.com/forum/battery-mods/106016-how-build-puck.html

easiest mod you'll ever build

 

[bstedh]

http://www.e-cigarette-forum.com/forum/modders-forum/192940-flashlight-mod-extras-keep-mind.html

I was able to put everything for this together at the hardware store minus the battery and connector.

 

[AttyPops]

Yeah, the 317 will only give you 3 volts to begin with. At 2.0 ohms that's 1.5 amps at 4.5 watts (all theoretical). Might work. I'd puck it. Even 3 NiMH batteries will give you 3.6 volts. You can get the chargers at radioshack too (with car adapter????). Batteries sold everywhere. Not sure about using 3, so I'd research which batts to get and ask if 3 will work 1st.

Also, charging the not-being-used Riva sounds like a good idea. Should be able to use the car adapter for that with the charger for it.

 

[CraigHB]

For a battery-less USB pasthru, one standard rectifier diode (i.e. 1N4001) will drop a volt at atomizer currents. If all you can get is the round 1A through hole rectifiers, you can parallel a couple of them to handle the current. Though, you should try it just hooked up straight to your USB cig lighter adapter. At that current, the wiring and adapter will probably drop enough voltage to work well with the 2 ohm cartomizers anyway.

 

[interestingfellow]

Few things:
Thank you everyone.

@Bestdh:
I'm glad to see google working well. The links posted for the puck were the only real result I had found of worth, but thought "the puck" was a "buck" for driving LED's, which is why I asked for a link, but it turns out I had already found it.

@Attypops
I don't think I was clear about my Riva. It's what I use all the time, and the only Pv I've got for the moment. On the car trip, I'm going to vape battery A till it dies, and move on to battery B while charging battery A. Battery B will be dead before battery A is done recharging, and I'll have to man up, and just not vape till something is recharged.

I dunno. I'll rumage around tomorrow, see what I can come up with, and report back....

Thanks agian, everyone, but i'm off to bed.

 

[Java_Az]

After thinking about it sitting here sipping on my beer. I have a USB 2 amp hub , or it is supposed to be anyways. It actually only puts out 1.65 amps fully loaded. If your's is close to being the same you would be ok just making a straight through PT. You could do a load test on your car USB adapter and see what your max output really is. Seeing how china loves to over rate there crap these days you got a good chance of not needing any kinda regulator or extra circuitry to make you a PT.

Edit: just ran the numbers even if your adapter can put out 2 amps. A 2ohm atomizer will make it drop to around 4 volts under load. Not too far off of 3.7 volts you might just like the vape at that voltage.

 

[AttyPops]

Cool. Guys...For future reference, what about the 3 NiMHs for mini-puck idea? Does that work? That's 3.6 volts. I think NiMH's have plenty of amps....

@interestingfellow: OK, I'm surprised, but you did say they are on their last legs. Sorry to hear that...I thought the Riva recharge time was quicker than the vape-time. I'd still puck it. Then you are portable and not tied to a car.

 

[interestingfellow]

@Java
You are correctish. I need to start closer to 4v and then get the drop down into the 3's, or I'm afraid I'll scorch my juice/carto filler.

I was thinking of winding a small transformer, but don't know enough about the math. 4 secondary windings for 5 primary windings would drop me down to 4v and up the current available. But Im not sure how big it'd need to be to handle 2 amps?

Attypop;
You are correct, and thank you for the condolences. I have to say though, I've been riding these 2 batteries pretty hard for 3 months (3-5mls/day, 2 batts per day), and they are just now performing noticeably less.

 

[bstedh]

A transformer only works for A/C current. They are used in switching regulators by switching between positive and negative giving a sudo A/C current. DC will have no effect on a transformer.

 

[interestingfellow]

uhhhh....I thought xfrmrs work in ac or dc; otherwise car audio amplifiers, automotive usb power supplies, and a ton of other things wouldn't work. Correct me if I'm wrong, please.

Well, anyway, I decided to build a puckish device. 1 4AA holder, with 3 cells at 3.6v total, and 1 AA worth of space for other guts; that way I can also take it on the boat with me too,and not worry as much. I went and got the 3amp switch and box this morning. I was going to go to harbor freight or AA NiMh, but found two 9.6v 1000mah battery packs in my "bin" (collection of random shizzle). They are the 14500/AA size, so it should be ok physically. Would NiCad be ok to use (instead of NiMh)?
If so, then I have 16 rechargable 1000mah batteries!