Does this basic scematic look right?

[KarrMcDebt]

This would be a multifunction mod. It would work as a usb passthrough/charger and a 3.7v/5v mod.

It will use 2 x 14500 batterys wired in parallel, outputting 3.7v (4.2v on a fresh charge) @ 1800 mAh.

A 3 way switch will select between 3.7v (dirrect to atomizer)/ off / 5v (run through T.I. 5v Booster chip). All 3 options are available regaurdless of the power source.

When ever the mod is plugged in to USB power it will trickel charge the batterys.

Anyone see any errors on the circuit?

 

[Rocketman]

atch the polarities of course, but looks good to me (the guy that almost cost you an atty ).

Some models of the TI booster need a programming resistor (adjustable output models), and anything 10uf or over would probably work on both ends. Switches will have to handle the current (which will be higher than atty current on the input side of the booster).

Go for it, but use an old atty at first

Rocket

 

[WillyB]

Well if this is the booster you are using, why not use it to it's full potential.

Digi-Key - 296-20500-ND (Manufacturer - PTN04050CAZ)

3.7V seems un-needed. Why not use a 4 position switch, off- plus 3 voltages of your choice. The range can be determined by using small resistors. Let's say 4.1, 4.5 and 4.9V. You can go lower and a bit higher.

You also show a 'USB pass through circuit' which would denote a direct firing of the atty which would require about 1.8A+. But later you say 'trickle charge' your batteries. You can't trickle charge Li-ions. You need a legitimate charging circuit that outputs about 4.2V and will cut-off when the battery gets there.

Peruse Nuck's guide (one of the best I've ever seen). You should be able to glean a ton of worthwhile info.

https://docs.google.com/Doc?docid=0AXdaMZo4FKMVZGhqdnE4YnNfNDNjN2Q0cHBoZg&hl=en

Also the correct and spec sheet recommended LOESR caps are much smaller and easier to fit that the RS cans.

Here's a pic from tinear's work w/caps installed.