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Shadowlife25
07-06-2010, 02:03 AM
IIRC, you do electronics yes?

I need some major help and have a definite deadline. :(
I won't lie, I am not sure I am up to the task.

I will wait until you replay to post details.

klapa
07-06-2010, 02:20 AM
IIRC, you do electronics yes?

I need some major help and have a definite deadline. :(
I won't lie, I am not sure I am up to the task.

I will wait until you replay to post details.

Here is my reply - yes I design electronic hardware and I know all about deadlines - tell me what you need and I will try to help.

You can post here - send PM - or email - your choice.

4thgenceli
07-06-2010, 02:22 AM
He had me boggled... but then again I'm a computer nerd (oh wait..what does that say to my computer skillz...:onsnap:

Best of luck Mario!

Shadowlife25
07-06-2010, 02:28 AM
Good god I hope you're ready... sigh.. here goes:
This needs to be in the absolutely smallest package possible. FML...

Power is from 2 Li-po protected cells rated at 3.7V (single) and 900mAh
5-7V booster circuit to
5-?V 5A Regulator with control pin (for use with momentary microswitch)
Female Micro USB charging circuit to suit charging at 200mA while simultaneously using the device.
LED driver to monitor charge level of power source (3 LEDs)
Adjustable voltage to suit 3.7V to 7V output with 5A max.

My brain is scrambled right now.... :(


*EDIT*

Needs to handle a continuous 2-5A drain.

Use of a PWM circuit to pulse the current would be *ideal*

klapa
07-06-2010, 03:01 AM
OK - so trying to "sort things out" here -

You need to design a boost switching regulator that is driven by lithium-Ion batteries.

The load is 3 LED's - not knowing what type we will assume here for the time being that they are ~3.25V each.

I'm not sure if you specified what current you want to run these LED;s at - they are HB LED and you want to run them at ~500ma - ~10000mA?

Everything is no prob to do "fast" - except the "USB charging" part - that might not be so quick.

Else all is a simple boost regulator which I have built in the past - and have a good selection of part and circuit possibilities right here at my fingertips for you.

Generally speaking - PWM is always used in a switching regulator - and also secondary PWM is used for dimming LED in selected designs.

I will post a couple of circuits for you here.

Shadowlife25
07-06-2010, 03:01 AM
It isn't to drive the led's, I just need those to indicate:
Master switched power: ON
Momentary power: ON/OFF (Illuminated/off)
Battery Charge level indicator: FULL/HALF/LOW (BLUE/GREEN/RED)

It is to have a coil across the output rated from: 1.2-4.2Ohms (varies on coil used)

Current to the coil will be from: 3.7V-7V

PWM circuit to pulse the power to the coil to preserve battery life.

Batteries will be 2 (two) Ultrafire 3.7V 900mAh Protected cells.

Shadowlife25
07-06-2010, 03:08 AM
some things I was looking at that may or may not work...


Also there is a TI chip that may work out well for the booster

Shadowlife25
07-06-2010, 03:10 AM
Another pdf I have will not load. It's too large... meh

Shadowlife25
07-06-2010, 03:19 AM
Klapa?

Where'd ya go bud? :)

klapa
07-06-2010, 03:36 AM
It isn't to drive the led's, I just need those to indicate:
Master switched power: ON
Momentary power: ON/OFF (Illuminated/off)
Battery Charge level indicator: FULL/HALF/LOW (BLUE/GREEN/RED)

It is to have a coil across the output rated from: 1.2-4.2Ohms (varies on coil used)

Current to the coil will be from: 3.7V-7V

PWM circuit to pulse the power to the coil to preserve battery life.

Batteries will be 2 (two) Ultrafire 3.7V 900mAh Protected cells.

OK - I'm trying to get my arms around this one - and some things are easy - others are rather difficult to understand the meaning.

What is the difference between "master switched power" and "momentary power"?

The battery charge level indicator is easy - so long as you are able to "throw money at the problem" you could just use the old LM324 quad op-amp and with a voltage divider and drive your three charge indicator LED with up to 50 mA.

Whats up wit this "coil" that seems to be our main load - what does it do - what is it for?

You say the coil is ~1 ohm to 4 ohm - that is a really low ohm coil that would take allot of power to drive!

What the hell is it - is this a "hypothetical University" circuit - or something real?

Either way - i want to help - just want to know what i am up against.


Klapa?

Where'd ya go bud? :)

Still here.

Shadowlife25
07-06-2010, 03:52 AM
It's real.

The "coil" is a nichrome wire that is used to atomize a liquid.

The "master switched power" is a simple on/off switch.
Idea being, the momentary switch can not activate without it on.

Momentary switch is solely to apply power to the coil at user determined intervals.

I have other ideas as well, but I need this hammered out before I can make my presentation.

Deadline is August 7th for me to have a real shot at seeing something come of this.

klapa
07-06-2010, 03:52 AM
OK - I have looked at those links and they are common regulators which is fine - but what is the load? That IS the question - it is a coil that is 1 ohm to 4 ohm but is this a continuous load or is it an intermittent (switched) load?

Shadowlife25
07-06-2010, 03:53 AM
You're welcome to call me if you have the time :)
PM for my # if you like, though it is likely late for you.

Shadowlife25
07-06-2010, 03:55 AM
It is a switched load sir. :)

Push momentary switch to activate circuit and apply load to coil.

klapa
07-06-2010, 03:55 AM
Ok - nichrome wire makes sense - but for me - that is a resistive heating element - not a "coil".

Just a matter of semantics - and the important thing is that we understand each other.

Shadowlife25
07-06-2010, 04:03 AM
Ok - nichrome wire makes sense - but for me - that is a resistive heating element - not a "coil".

Just a matter of semantics - and the important thing is that we understand each other.

Yessir. :)

I called it a "coil" as that is the typical arrangement for it in this instance.
More by necessity to achieve the required form factor and provide maximum surface area.

We don't need to reinvent that though. ;)
Those are pre-made. Hence the listing of potential values being 1.4-? Ya know?

But yes, you are correct 100%. It is a resistive heating element.:beerchug:

klapa
07-06-2010, 04:09 AM
So - for the first part - the "battery charge indicator" with the three LED.

If you want - I will make you a circuit. I would base this on the relatively inexpensive LM324 quad op-amp ($0.25). To do that - I need to know the "nominal" battery voltage range that would be green - the middle battery voltage range that would be yellow - and finally the threshold for the low "red" voltage. I can make the circuit and explain it too - as it would only be a voltage divider "ladder" with op-amp inputs on taps to drive the LED indicators.

Note that if you actually need copper here - I have the chips and prototype materials on hand - but I'm not sure if I actually have the time to do it ALL.

Tell me what you need and I can deliver it - because that is what I do everyday.

rizin
07-06-2010, 04:10 AM
What is up the mad scientists sleeve? Following t.his

Shadowlife25
07-06-2010, 04:11 AM
PTNO4050C is the pn# for the Texas Instruments Booster i was referencing.

klapa
07-06-2010, 04:14 AM
So - now lets just "hone in" on the load requirements.

The load is a nichrome wire heating element.

This load a) IS b) IS NOT continuously "energized".

Assuming "B" is the answer - the load is PWM controlled - but what is the feedback? What determines the "on-time"?

I'll look above - perhaps the answer is already there.

Shadowlife25
07-06-2010, 04:22 AM
So - for the first part - the "battery charge indicator" with the three LED.

If you want - I will make you a circuit. I would base this on the relatively inexpensive LM324 quad op-amp ($0.25). To do that - I need to know the "nominal" battery voltage range that would be green - the middle battery voltage range that would be yellow - and finally the threshold for the low "red" voltage. I can make the circuit and explain it too - as it would only be a voltage divider "ladder" with op-amp inputs on taps to drive the LED indicators.

Note that if you actually need copper here - I have the chips and prototype materials on hand - but I'm not sure if I actually have the time to do it ALL.

Tell me what you need and I can deliver it - because that is what I do everyday.

Nominal = 4.8~7V
Median = 3.7~4.7V
Low = 2.7~ 3.6V

Somewhere in the rest of the mess, I'd like a "cutoff" (shutdown) at the 2.6V point.

Shadowlife25
07-06-2010, 04:24 AM
So - now lets just "hone in" on the load requirements.

The load is a nichrome wire heating element.

This load a) IS b) IS NOT continuously "energized".

Assuming "B" is the answer - the load is PWM controlled - but what is the feedback? What determines the "on-time"?

I'll look above - perhaps the answer is already there.

"On-Time" is determined by the user and is actuated by the momentary switch.

klapa
07-06-2010, 04:30 AM
I will make a pSpice circuit as a model - which is easy to do - this will serve as our "block diagram" and a starting point for us to refine and further understand each other.

The good thing about doing it that way - is we can also simulate different conditions and see the circuit waveforms.

Shadowlife25
07-06-2010, 04:33 AM
Sounds good. :)

I have just gotten Ultiboard and Multisim, but I haven't used them in over 10 years, so I am pretty lost.

I'll be waiting in here.

Alone...

In the dark...

;) lol

rizin
07-06-2010, 04:51 AM
Something that I might throw in with using Li-po is I thought the voltage drops off like a wall with them.

Shadowlife25
07-06-2010, 04:54 AM
Exact batt I am plannig to use (though others similar can be used) is:

UltraFire LC 14500 900mAh 3.7V with Protected Circuit.
Full charge and Empty condition is 4.2V and 2.7V respectively.

joe's gt
07-06-2010, 04:55 AM
Is Li-po battery technology reliable yet? Don't they have specific charging requirements that require a battery management system?

Shadowlife25
07-06-2010, 04:58 AM
LiOn is this model and is what will be used :)

But the design we are trying to hammer out here includes a management system.

Joe, I may have some 3d modeling stuff for you later once this is done, if you are up for it :)

Simple compared to the stuff in the intake thread. :D No flow analysis!

joe's gt
07-06-2010, 05:05 AM
Joe, I may have some 3d modeling stuff for you later once this is done, if you are up for it :)

Simple compared to the stuff in the intake thread. :D No flow analysis!

Sure, np. Its just the trial and error in the flow analysis that is tedious. Modeling goes pretty fast.

klapa
07-06-2010, 05:05 AM
Ok - to reiterate and articulate the requirements of the circuit here:

This circuit is powered by Lithium Ion batteries of ?? Volts.

Such circuit requires an three LED indicator of high, middle, or low battery voltage - and such an indicator will be provided by the TI chip you cite.

The load for this circuit is a nichrome wire heating element with a resistnce that is variable between 1 to 4 ohm - and the voltage is applied to the load by means of a human actuated momentary switch.

The battery shall be rechargeable vi the USB connection to PC (5V nominal) - but there is no requirement for USB communication to this device.

So - last - but not least - what mode is the nichrome wire heating element to be driven - constant voltage from the battery - or constant current from a regulator driven by the battery?

Shadowlife25
07-06-2010, 05:14 AM
Ok - to reiterate and articulate the requirements of the circuit here:

This circuit is powered by Lithium Ion batteries of ?? Volts.

Such circuit requires an three LED indicator of high, middle, or low battery voltage - and such an indicator will be provided by the TI chip you cite.

The load for this circuit is a nichrome wire heating element with a resistnce that is variable between 1 to 4 ohm - and the voltage is applied to the load by means of a human actuated momentary switch.

The battery shall be rechargeable vi the USB connection to PC (5V nominal) - but there is no requirement for USB communication to this device.

So - last - but not least - what mode is the nichrome wire heating element to be driven - constant voltage from the battery - or constant current from a regulator driven by the battery?

2x 14500 batteries in series to provide 7.4V at 900mAh

USB is for charging/pass through only.

Heating element is powered by the regulator.

There should be a POT to adjust the regulator from 3.7~7V

rizin
07-06-2010, 05:43 AM
Hey look at the Graph of discharge characteristics of li-po's to its cut off. Your led voltages might have to be diffrent for the half and dead led that is all I was saying. 2.7 is no more power. http://www.fmadirect.com/lipo_handbook/FMA_Lipo_Handbook_Section3.htm#_Toc109185763.

Shadowlife25
07-06-2010, 07:13 AM
LOADED VOLTAGES (@ 2.3ohms)
1. 4.26V - 7.89W
2. 4.65V - 9.4W
3. 5.23V - 11.89W
4. 5.49V - 13.1W

I would prefer the #1 setting be closer to 3.8~4V
Other loads are as low as 1.4Ohms...

Shadowlife25
07-07-2010, 12:36 AM
Afternoon bump :)

4thgenceli
07-07-2010, 12:49 AM
Is Li-po battery technology reliable yet? Don't they have specific charging requirements that require a battery management system?
I use lipo batteries in my brushless RC cars.

I have a charger/balancer that does all of that for me. Only thing to watch out for is damaged cells (indicated by swelling). Once it swells, wrap it in the fireproof lipo bag and dispose of (otherwise you have a mini grenade on your hands).


I see no issue with them being stable as long as they're properly used & cared for.

Shadowlife25
07-07-2010, 01:08 AM
Got in today a sample of Maxim Integrated Products MAX1811ESA+

Let me know what you think of that one as a potential part

klapa
07-07-2010, 01:41 AM
Hey - didn't mean to "run off" - just kind of "fell out" :)

Rizen has it right to state that Lithium Ion batteries and even more-so Nickel Metal Hydride have a "wall".

What that means is the "discharge curve". Look at some datasheets - Panasonic is pretty good for those.

For a regular alkaline type battery that is no rechargable - the voltage of the battery will decrease pretty much linearly as the capacity (charge left) decreases. When the battery is completely discharged - the voltage will be nearly nil.

This is not the characteristic of Lithium Ion batteries or Nickel Metal Hydride - these batteries will charge up to some voltage a bit higher than their characteristic cell voltage - and then on discharge quickly assume their characteristic cell voltage and maintain that voltage within a few hundred millivolts until they are exhausted. At that point - they cease to be able to supply the load current (power) and their voltage will be very low while loaded - but when the load is removed their voltage will be very near the cell voltage.

Nickel Metal Hydride has the "steepest" curve - followed by Lithium Ion.

So.what the above means is that really - you don't need the "high middle and low" comparators - just a "charged and dead" indicator.

Another aspect to consider is the desired use of the USB 5VDC to charge the batteries.

USB "hosts" (computer USB ports) don't "automatically supply 5VDC to the USB port red and black wires - there must be a communications protocol that transpires between the remote device and the host that "asks" for the power before i is supplied.

Also - the maximum current available from any one port is 500mA.

Thus - first to use the USB port voltage you will need some device with the "intelligence" to "ask" for it - and then to charge a 7V battery with 5V you will need a boost regulator.

Is it not possible to simply use a "wall wart" type power supply for the charging?

Shadowlife25
07-07-2010, 01:46 AM
Klapa, gimme a call if ya like. You have PM.

klapa
07-07-2010, 01:57 AM
Asking again about the load - as that is really where it all starts.

You know - for a fact - that the load varies between 1 Ohm and 4 Ohm during operation? Noting here that any resistive heating element - such as nichrome wire - has "cold ohms" and "hot ohms". That meaning that any resistor has a positive temperature coefficient - the resistance increases with the temperature - and the worst case "surge current" at cold temp must be taken into account for the driver.

I ask because such resistance spec for nichrome wires seems really low - but perhaps your heating element is only and inch or two and then it would make sense.

Shadowlife25
07-07-2010, 02:43 AM
PM'd you the link to a walkthrough on what I am talking about Klapa :)

klapa
07-08-2010, 01:25 AM
I'll check for PM's - I'm looking at the MAX1811ESA datasheet now.

I will tell you - I've been burnt by Maxim on a few occasions in the past.

The deal with Maxim is that - generally - they can't deliver their parts. It is said by many engineers and vendors too - that "they make great datasheets". Some of their parts have 40 week lead times!

This one you like has four package options and all but one have a lead time listed as "TBD" - which means "too be determined". One of those parts lists a lead time of 6 weeks which is not so bad - especially right now - but again - Maxim is NOTORIUS for not being able to deliver in time.

I'll finish looking through that datasheet and let you know my comments - but it does look like a very good solution for what you want to do - and already has the "charged" comparator output on-chip.

So - it looks real good - the statement is made that it "connects seamlessly" to the USB host and polls such for the current capability.

It has the correct regulator action to run in a constant current mode until the cell is charged and then switch to constant voltage mode for a "maintenance charge" and to prevent over charging.

It is in a "thermally enhanced" SO-8 package - and what that means is that it has what I call a "belly pad" on the underside of the IC body to help dissipate the power - that is fine for a PCB but a little more of a challenge for prototyping.

Note it is designed to charge a single cell - 4.1 to 4.2V at 500mA - thus while you might have two in parallel - you won't get your 7V output without some sore of a driver there.

Shadowlife25
07-08-2010, 03:58 AM
Ok, I actually have in my hand right now the following:

Maxim: MAX1811ESA
Texas Instruments: PTN04050CAS
Generic: 5V 3A Regulator (4pin w/control pin for low mA switch)
2x 3.6V 900mA Ultrafire Protected 14500 batteries (3C dc rate)
10mF 25V Capacitor (+-20% tol)
1 tri-color LED
1 470 Ohm Resistor

klapa
07-08-2010, 04:22 AM
Ok, I actually have in my hand right now the following:

Maxim: MAX1811ESA
Texas Instruments: PTN04050CAS
Generic: 5V 3A Regulator (4pin w/control pin for low mA switch)
2x 3.6V 900mA Ultrafire Protected 14500 batteries (3C dc rate)
10mF 25V Capacitor (+-20% tol)
1 tri-color LED
1 470 Ohm Resistor

I looked through your PM links - and I am still confused about what exactly we are "making" here.

You can call me anytime - let me know what I can do to help.

I have some "extra" boost regulator boards that I could send you just for testing purposes in case you need something like that.

Shadowlife25
07-08-2010, 04:26 AM
We are constructing a better mousetrap... aka electronic cigarette. ;)

Shadowlife25
07-08-2010, 04:28 AM
I think it needs a 5 position "click" style switch instead of a potentiometer...
May be easier to have just the 5 pre-set voltages.

*EDIT*
It is a 470kOhm Resistor, not 470 Ohm.

Shadowlife25
07-08-2010, 05:19 AM
Few bits of info...

Shadowlife25
07-19-2010, 01:05 AM
I have parts on the way Klapa. This thing may see a proto as soon as 2 weeks, so Your help is appreciated :)

JoesGt: If I send you a jpg of the casing with measurements, could you do me a solid and make a CAD file from it as well as a solidworks file?
I need one for the CNC at the machine shop and one for a visual to show proof of concept and interested parties.
You would be doing me a HUGE favor sir.

Thanks to you both in advance :)

celica9303
07-19-2010, 03:14 AM
Interesting read . No clue what were making or why but its interesting hope it works and you disclose the true mousetrap once complete

andy
07-19-2010, 04:25 AM
i was gonna guess a vaporizor.

Grot
07-19-2010, 04:33 AM
It basically is a vaporizer. It an electric cigerette.

celica9303
07-19-2010, 10:26 PM
Why? Sounds cool either way

klapa
07-21-2010, 01:07 AM
I have parts on the way Klapa. This thing may see a proto as soon as 2 weeks, so Your help is appreciated :)

JoesGt: If I send you a jpg of the casing with measurements, could you do me a solid and make a CAD file from it as well as a solidworks file?
I need one for the CNC at the machine shop and one for a visual to show proof of concept and interested parties.
You would be doing me a HUGE favor sir.

Thanks to you both in advance :)

Shadow - I looked at your boost converter - it seems good but is "pricey" and also - like the Maxim chip - in short supply (long lead times). The other part of that is the "power budget" for charging the batteries if you want to use USB - it would take a long time - depending on usage and discharge rate.

I will PM you later this evening - and send my phone in case you don't already have it. You will need some prototype materials to implement your "test bed" - I think I can help there.