Going for VV.

[vereybowring]

After many weeks of procrastinating, I am going to try to build some variable voltage mods using the boxes I already have.
Parts have been ordered and I nervously await their arrival.

There are two types I am looking into;

voltage limiter based VV where a circuit controls the power from two batteries in series cutting them down to the required level - this should fit in the triple AA size box but if I use a pair of 16340's I could get it smaller.

the other method is to use a boosting circuit to raise the voltage from the standard battery up to the level required - this will need a bigger box since the circuitry is more complex.

I have parts on the way for both types and will let you all know how I get on.

Cross things folks, I hope I can get working prototypes soon.

[curtisdon1]

Good luck I'll be interested to know how you get on

[deejay]

Good luck with this mate... Sounds promising!

[MIDIManNI]

Look forward to seeing this Verey...

Later...

[vereybowring]

The first part arrived already, a TI PTN04050CAD.
It is best suited to being a 3.7V booster to achieve that lovely 5V output.
It can however be made to have a range between about 4.5 to 6.5 V which is nice.
I notice some people got several as free samples but texas instruments only let me have one - wonder if they've noticed all the free samples they've been giving out and are now limiting the freebies.

Anywho, I'll play with it once other parts arrive and let you know how I get along - it's really small so could even fit in the 2AA case alongside a single 14500 battery which is nice.
Can only make one though since I only blagged one chip.

[ian]

Good luck with your VV mods mate.Im very interested in anything VV so if they are a success then please count me in for a purchase.

[mikrosoft]

Aug 17, 2011 15:22:36 GMT vereybowring said:

The first part arrived already, a TI PTN04050CAD.
It is best suited to being a 3.7V booster to achieve that lovely 5V output.
It can however be made to have a range between about 4.5 to 6.5 V which is nice.
I notice some people got several as free samples but texas instruments only let me have one - wonder if they've noticed all the free samples they've been giving out and are now limiting the freebies.

Anywho, I'll play with it once other parts arrive and let you know how I get along - it's really small so could even fit in the 2AA case alongside a single 14500 battery which is nice.
Can only make one though since I only blagged one chip.

Have used a few of these chips got my last lot from ti free yesterday,You have to order all the range the only difference is the solder pin length here is a good circuit diagram

[vereybowring]

Yeah the TI chips are excellent.

I was thinking of building the VV circuit using one into one of my monster mod cases.
Instead of two batteries in parallel I would only have one 18650 battery in it but that would leave room for the boost circuit as well as the charging circuit and an LED voltage readout - instead of a rotary potentiometer I would use a slide one on the side of the casing making adjustment more intuitive.

I am a great believer in having my units as self contained as possible and this would make for a powerful and rechargeable VV device.
Won't know for sure if I can get it all in the case till more parts arrive but it should all fit.

If it works it would also be worth actually buying some of the TI chips to make the production versions - yes it would raise the price but I think people would still go for it.

[vereybowring]

I now have several of the TI chips so will start experimenting with them once I have a supply of smaller sized potentiometers to hand.

Also today I got a couple of circuit boards from china I won on ebay.
One circuit is a step down one which isn't any better than what I made myself with an LM350T so I won't be using for anything since it's bigger.
The other circuit was a boost one which was very surprising, I wired it up to a single 16340 battery and at max it was outputting 14.9 V just not for very long - would be great if the board didn't normally cost £6.00 and was so big. It's a similar board to one many have used for VV devices before me including steeljan's.
The pre-made chinese boards are all right except the potentiometer they use are those cheap multi turn screw types which are crap for easy adjustment.
So after an experiment with buying pre-made circuits I now know I am better off building my own since I then control the parts used and the form factor of the finished product.

[vereybowring]

I now have plenty of the TI chips to play with and have smaller potentiometers on their way.

This means I should be able to start actually making VV devices with them next week.

Also I will make a few of the step down voltage VV's since I have the parts but this is a less useful layout since it's unlikely I could have a charge circuit built in too.