Circuit board to handle charging with batteries installed?

[cadcoke5]

I am designing a smoke generator for someone with a puppet dragon, so it can breath fire. It will use a small fan to blow air into a pair of "clearomizers" like one of these; Vision eGo Clearomizer 2.1-2.4 Ohm

I realize that if I put these in parallel, I am looking at a very high current set-up. If my decades-old electronics education serves me now, that would be perhaps a 1.1 Ohm load, at 3.7v = 3.4 amps and 12.4 watts.

But, this parallel set-up really is preferable, so that if one of the atomizers fail, the other will still be working.

It may typically run at full current for 20 seconds max, but I should allow for the possibility that the user may hold the button too long... perhaps much too long.

To make the maintenance as easy as possible, I would prefer that the batteries be charged in place. This should be usable by someone with no electronics knowledge. So, a simple plug-it-in and it starts to charge is needed. It does not need to "vape" while charged in, so that is not an issue.

I have been looking for some circuitry that would allow me to charge with the batteries installed, and also provide for some other types of protection, such as running at full current for too long. I know batteries can come with self-protection, so that does not need to be in the circuit.

I have not been successful so far. Any recommendations?

Joe Dunfee

 

[jmarkus]

evolv sells the "dna charger"

if your running parellel batts it should work fine (wont work in a series):

Our Products « Evolv

DNA Charger

Our Micro-USB charging module lets you add the functionality of onboard charging to your DNA 12 project or can be used as a standalone charger for non-DNA projects. It is designed for charging 3.7V 1S Li-Ion and Li-Poly cells. An onboard status LED illuminates red when charging, green when fully charged, and orange when no battery is present. Mounting holes for #2 screws are provided for easy attachment.

sparkfun.com also has a few mini/micro usb charger boards.

 

[cadcoke5]

Thanks for the reply. I had come across some references to the DNA and also the Nivel as I continued to research after that posting. Then I just spent about 4 hours unsuccessfully trying to find a place to buy either and to get a price.

I am now also aware that these systems allow the battery to charge in place with any of the USB chargers.

So, there is the sticker shock for the whole system, but at least there is a solution. I may actually start the system with simpler electronics, and then upgrade it later if warranted.

By the way, I always find it ironic when people like to invoke Darwin or evolution, when they really are hoping to promote their own intelligent design.

Joe Dunfee

 

[tumbleweed65]

I'm trying to come up with something like this for the front of my bike.....I have a dragon head I would like to fog at will.I'm pretty good mechanically but electronically challenged.

 

[bapgood]

I just spent about 4 hours unsuccessfully trying to find a place to buy either and to get a price.

The DNA charger can be purchased here for $8.50 shipped anywhere. The DNA charger is tinny and simple to use.

 

[MorpheusPA]

You could, I suppose, use a simple 555 timer to activate the transistor that fires the atomizers. Done in monostable mode, you could design an X second pulse.

You wouldn't be able to fire the atomizers directly with the 555, the chip won't handle that much power. But it can certainly activate the base of a MOSFET transistor that fires the atties!

 

[cadcoke5]

I'm trying to come up with something like this for the front of my bike.

See a separate thread I started about this.
http://www.e-cigarette-forum.com/forum/modding-forum/339709-pipe-emits-smoke-while-untouched.html

But, as soon as you start taking something like this outside, even a small amount of wind quickly overwhelms the fog. You might be better off trying out a commercial product that can produce fog with a 12v supply (typically by battery). Of course, be prepared for sticker shock.

"Tiny Fogger" by Look solutions. I have seen these for $300 to $400 used on E-bay.
The Antari M-1 fogger. Around $300 used, and new around $800.

A possible alternative for you might be to spray out water, if you can rig up a set-up that will put out a fine mist with enough force.

For the "fire" part of the display, I am using super-bright LED light sources. For your needs, there is an abundant supply of 12v ones out there. However, they may not have the narrow beam which is best for this sort of thing.

Joe Dunfee

 

[DrSeuss]

Someone has already said it, but sparkfun do a single cell charger for a few bucks. Uses Micro USB and stops charging when the device is in use. Thinking about it, I would recommend using an ultrasonic atomizer to generate a good volume of mist. I think clearomizers will not give the volume of smoke needed for an impressive effect.

 

[cadcoke5]

I think clearomizers will not give the volume of smoke needed for an impressive effect.

I agree. The plan is for the smoke to accumulate in a container in the puppet's belly for perhaps 10 or 15 seconds. I also plan on using two or more clearomizers at once. Then, a canned-air duster will blow the smoke out of the container.

The ultrasonic mist idea is a problem because we can't seal it up in such a way that it won't leak if the puppet is tilted over. Also, it just doesn't look right, since it is a very heavy and cool fog, that tends to look like dry-ice fog. Smoke should rise, not sink.

The dragon in this case, is a Chef. She uses the fire-breathing to do her cooking. Also, when you cover something with dense smoke, the smoke tends to linger on the object and rise from it. This which would really help show the idea that it is being cooked by the fire.

I have attached a preliminary sketch of the system. However, note that we are moving the smoke generator and container out of the head and into the belly. We are also considering using a solenoid to actuate the air can. But, that probably means going to a 12volt battery, which I would like to avoid if I can.

Joe Dunfee