Hotwire LDO driver! 13mv drop with 1185

[andrewwynn]

yup about 9W is what i estimated.. i didn't do all the math but my estimate was that it would run about the same time just w/o dimming... actually the switch that the mosfet would be replacing has more resistance so that's a wash. And yes.. no more insta-flash but also.. could set the output voltager higher than the nominal voltage if the bulb can handle it.. i.e. 11 cells = 13.2V... with 12 cells i could use 13.5 or something.. that is still way less than the 15.2 that 11 cells are going to have fresh off the charger.. the voltage 'ramps up' to full with this regulator.. probably in just like 20-40 miliseconds but still not instantaneous as well. I haven't done peak measurements with the current yet but the voltage measurements my meter only goes down to 1msec and there is no peak whatsoever.. does not overshoot the set voltage.

back to the non-dimming.. i've noticed that with heavy drain that NiMH are really exhausted at 1.1V... so.. 12 cells x 1.1V = 13.2.. coincidentally the exact same as 11 x 1.2... in other words i 'just now' did the math.. and it works out to no dimming 'til exhaustion.. when we've pulled 7-8A out of the CBPs we have been measuring 1.2V/cell still.. that's pretty exciting.. i'm sure the body will get warm around the switch from the mosfet heat sinking but as the bats. drain the FET losses drop, so it might not be that terrible, and like you said.. no worries about the bulb blowing.

-awr

 

[StoneDog]

hmmm... So does this Kiu socket work in a "C" sized mag? A 2C w/ 2x18650 and an 1160 would make a nice little light.

Jon

 

[andrewwynn]

There is a socket like KIU for C.. not sure if it's actually KIU.. and yes... 1160 and 2 18650s would be able to get you at least 800 lumen, the testing is going to start soon to see what realistic battery life you can get but i've been running the one on the bench hot enough to melt my breadboard.. about 860 lumen.. I got some advice that it's good to keep the bulb below 6.3V but when the regulator keeps the voltage below your set voltage i'm thinking it'll be higher possibilities.

-awr

 

[andrewwynn]

Ok.. finally had a bit of time between nano building to 'take a break' yeah right.. and fix the bug in the driver that was driving me MENTAL!

(the bug: the shut down ckt defaulted to 'off'... if it was connected at 'startup' it would say.. 'oh.. there is zero volts on the shutdown pin i must have already shut off' and the hysteresis program held it off no matter what the voltage.. aaarrrgh..

So.. squashed the bug.. glad i was doing the testing at low voltage (1160 bulb).. because as it turns out.. much harder to fix at lower voltages.. when i moved up to the 1166 bulb the problem was much less of a problem.

Oh.. i managed to bump off the voltage setting resistor with the 1160 bulb in there... and it puts Vbat to the bulb in such a case.. i couldn't figure out why it didn't seem to be regulating but the only way to be sure it so turn up the voltage 'til the output voltage stops climbing... well.. the voltage stopped climing at about EIGHT VOLTS... it went right to ZERO! oops! well fortunately i had a different bulb to finish the work... i think i need some more 1160s though i'm clean out.

Oh i just have to know so here i go look.

8.0V on the FIVE volt 1160 stats look like this: (yes i'm completely aware the calculations aren't that accurate when going more than 20%, but it's still interesting!)

4.47A... 35.7W.. 1700 lumen.. 47.4 lumen/watt.. 3761 CCT.. 107% overdrive.. and 66 degrees Kelvin above the melting point.. it did last approximately 1.0 seconds... but i was 'ramping' the voltage.. and in the mid seven volts.. wow did that look pretty!

Now onto the more serious...

First i tested out the circuit with a $4 westinghouse 12V 20W bulb.. and preset the voltage to about 12.5.. so it would be close so i could run the 1166.. the voltage was within 1/10th of a volt when i switched to the 1166..

Setting the voltage input to 14.47 V to simulate running from 4x LiON.. the bulb was getting 12.5V.. at 2.04A.. changing the input voltage from 16.8V to 14.0V (dead cells).. there was no appreciable change in bulb voltage.. 12.50V the whole time..

That works out to:
914 bulb lumens
594 torch lumens.. of course in my case there is not torch.. just the bulb sticking up out of the melting breadboard).
25.7 watts.
2.05 amps
35.6 lumen/watt..
8.2 hr expected life span
3533 CCT
12% overdrive
162K from melting point
86.8% driver efficiency. (just about 4W lost on the circuit)

I plan to run this bulb in a 2D host with a modamag 8AA->2D hacked into series-parallel... that will get me a 1.4AH 14.4V source.. running at 2.04A means about 40 minute runtime.. 900 lumen 2D flashlight.. (600 torch lumen).. it will also not dim in the least 'til the last minute where it'll plummet like a rock down to about 700 lumen before shutting off.

For fun i took a LionHead i had handy and held it over the bulb while i lit it up.. and holy cow what a nice bright light!

here's a picture of the thing operational on the bench:

the rest of the slide show is HERE

Darn, just noticed i unhooked the second meter which was typically either showing the bulb voltage or the LDO (which btw was 0.006V once the Vin is 12.506V or lower.. however the 15V is the current Voltage IN, not bulb voltage!

Oh some fun trivia on that picture!

Lot's of fun things to see.

the heat-sink for Fivemega's BAM is in the bottom left.. some progold sitting on top of a panel of nano PCBs just above that..

TWO fluke 87s.. a III and a V..

A bunch of nanos almost completed... i love the look of the chargers chips when still attached.. like solders in rows.. the light heads are on the board to the left of the chargers..

Looks like there is a bit of a spool of 10µF caps. .

The heatsink on the FET on the hotdriver got up to at least 182F!.. I was pushing it to the limit to see how much power it dissipated with fresh cells (16.8V!).. answer: 8.77W!

Just above the breadboard is my welders plate held onto a machinist square by a rubberband.. that is normally between me and the bulb for protection both from light and possible explosion of the bulb. It is really wonderful to see the likes of an 1166 running at 12.5V from less than a foot away but through a welder's plate!

In the magnifying lens.. you can see one of my favorite tricks, i hope somebody copies.. you can see the jaws of the vice i use to hold circuit boards while soldering.. and there is a spool of no-clean Kestrel (sp) solder... but see the round circles? those are stacks of magnets.. you can only see the 'top' magnet, but this is the arrangement.. i have 1/4 inch tall stack of 1/8th inch diameter magents.. two of those stacked near each other.. and on top.. a 1/4 inch diameter 1/8th inch thick disc magnet.. arranged like a 'stone henge' arch.. there are two of these and of course they are on the vice 'sideways' so 'top' is actually toward you..

This allows me to pull the solder around in a circle almost effortlessly.. but the magnets 'grab' the solder so it doesn't move much when i'm wetting the tip of the iron

Oh last mention on this picture... the bench power supply.. i honestly have no idea how i survived before getting it.. most useful tool in the shop.

It was less than $200.. it can do up to 60V at 3A or up to 6A at 30V.. has 4 digital displays showing the two independent supplies and their voltage and current..

So.. now that the circuit is completely operational and working exactly as planned.. I suspect in a week or so when i get around to maybe batch 4 of the nanos i'll take another break and finally get the driver assembled into my KIU socket into my 2 1/2D FiveMega.. so i can stop melting my darn 1185 bulbs!

Check back in a week or so.

-awr

 

[NewBie]

Setting the voltage input to 14.47 V to simulate running from 4x LiON.. the bulb was getting 12.5V.. at 2.04A.. changing the input voltage from 16.8V to 14.0V (dead cells).. there was no appreciable change in bulb voltage.. 12.50V the whole time..

That works out to:
914 bulb lumens
594 torch lumens.. of course in my case there is not torch.. just the bulb sticking up out of the melting breadboard).
25.7 watts.
2.05 amps
35.6 lumen/watt..
8.2 hr expected life span
3533 CCT
12% overdrive
162K from melting point
86.8% driver efficiency. (just about 4W lost on the circuit)

-awr

To use your 35.6 lumen/watt, thats at the bulb.

IMHO, it is always proper to calculate for losses in the circuit/"ballast"/regulator.

This drops to 30.96 lumens/watt, once you include your circuit losses.

Why did you choose to use 14.47V battery voltage for all the calculations? Did you figure that as an average voltage?

Lets say the 4.2V 18650 cells drop to 4V under load. 4x Li-Ion gives you 16V.
Losses for the regulator are 16V-12.5 = 3.5V, so you take 3.5V * 2.04A= 7.2 Watts loss. (1-(7.2Watts/25.7Watts))*100 = 72.1 % Efficiency. At this point, the total efficiency drops to 25.7 lumens per watt.

I see the small MoliCell ICR-18650J drops to 4V at 2A load, in the beginning, so thats why I used 16V. Figure you did everything at what you figured was the average?

 

[andrewwynn]

don't read too much into a 'freeze frame' of a non-static event.. 14.47 was just the Vin at that particular moment in time... that wasn't a battery.. it was my bench power supply and it was me aiming for 14.4 and over shooting.

LiON will drop to 3.6-3.7 within a minute of heavy use... i use AVERAGE voltage for my AVERAGE efficiency.. i always use 3.6V for nominal LiON voltage for such calculations.

yes.. the 35.6 lumen/w is the bulb.. i was just talking about the bulb in those numbers.. wasn't interested in the lumen/W of the whole circuit though it is a valid and interesting number.

The far more accurate calculations for that circuit are here:

Nominal Vin: 14.4V
Nominal Vout: 12.5V
Nominal Current: 2.05A.

Power in: 2.05 x 14.4 = 29.52
Power out: 2.05 x 12.5 = 25.625

That makes for 86.80 % nominal efficiency.. which is actually outstanding considering the amount of voltage i'm shedding at the current drive levels.

getting 914 bulb lumen from 29.52 W = 31 lumen/watt.

Yes.. at first.. when the batteries are actually 16.8V and about 9W is dropped on the regulator it's 'quite ugly' but that lasts less than a minute.. what you are not taking into consideration very well is the overall average.. since when Vbat gets close to Vbulb... say.. right at the LDO cutout.. 12.507 Vin and 12.500 Vbulb.. now it works out to:..

2.05 x 12.507 = 25.639W in
2.05 x 12.500 = 25.625W out..

that is 99.94% efficient.. dropping a mere 14mW on the FET! (there is only negligible other resistance in the circuit.. i will be using 18ga wire.. a total of maybe 2-3mohm resistance.. which will be about another 12mW loss.

When calculating for runtimes etc where it's important.. i always calculate the total circuit.. this was just to show the BULB values..

In the end.. the important thing is the average power figures and the average efficiency so i use average values for the calculations... the result.. very useful important real-world details like running 900/600 lumen from a 2D size light for 40 minutes.. that's pretty awesome!

-awr

 

[NewBie]

Ah good, so you do understand the 30-31 lm/W concept for the average lumens. This is important, as most incandescent setups don't have a converter, so it is essential to include it in the lm/W calculations.

Now taking this a little further. As you get into higher powers, than are used with LEDs, you get into an area where it is much easier to get into the 95-98% efficiency range with a switcher.

Remember that loss that is in your linear regulator? I think we said it was 7W or so at the beginning, slowly dropping to 4W, and finally petering off to nothing. Well, if you utilize a switcher, you can reduce that loss to under 1.25W, and with a little work, 0.5W.

Carefully selecting a switcher chip that can run to 100% duty cycle (and there are a number of them out there), you'd be able to recover an average of 3.5W or so during the drain, and lowering the load on the batteries, which increases the runtime.

You could even use a set of jumpers to select different regulation voltages, to accomodate a variety of bulbs, and even cell packs, making five or six cells, with low losses, quite possible.

Anyhow, something to think about.

 

[wquiles]

Andrew,

Is the circuit shown in post #12 above ready to go? Fully tested? I want to know since I want to start ordering some parts to build one

Will it work well in the 4.5-4.8V range for a WA1319 in a 1D running from 4 CBP1600 high current cells?

Thanks in advance,
Will

 

[andrewwynn]

there is one small modification to the circuit... in the 'optional' shutdown ckt i stole the 47uF cap from C4 (which is not used) and I'm using 50kohm for R3. In addition because i was having issues with load affecting output voltage i changed R2 to 4.7k.. but when i make the actual-size ckt w/o all the xtra wires i'll be trying to go back to 8-9 kohm.

One last change from the schematic currently listed is that the switch is reloacted to between C5 and pin 14... basically.. pin 3 is wired to hot via R3 and parallel to C5 (now 47uF).. and a switched jumper goes from pin3 to pin14... that's the enable or 'on' switch... the circut is powered continuously. It was only drawing like 17uA when disabled last time i tested but i'll be doing further testing wheni have the unit operational in a light of course.

The circuit is designed for use as low as like 1.5V but i've only tested it down to about 6.5V.

I would do like me and buy the DIP14 chip from like arrow or future electronics.. the other parts from anywhere.. RS makes a perfect little perfboard that you could use to solder onto and have a dip-socket you could use rather than using a breadboard.

I bought all SMD devices and plan to build my first prototype by soldering the SMT chips directly actross the legs of the device.

The picture above is the exact circut as shown in the schematic with a tiny modifcation to the shutdown ckt and the R2 as described above... it works absolutely brilliantly.. even when running the 1166.. the voltage at cutoff is 2.9V/cell on the batteries..

The shtudown/startup issue is more of a problem at lower voltages.. example.. if the batteries get low enough to 'shutdown'.. it would take about 6-8 seconds for C5 to charge enough where it would allow me to restart if voltage is applied... so it's conceivable you could put the batteries in and press the button fast enough that i won't startup... but waiting 10 seconds absolutely always worked... when running the 1166 bulb at 12.5V.. that reset 'wait' time is less than 2-3 seconds.. so there is a chance it will be a longer wait to first use after first installing batteries (this is only an issue after the low-voltage cutoff triggers and only the first time using the light after replacing power). That was the problem i had to fix.. before finding the right combination of where to cut power and what R and C to use.. it would only fire up like 20-60% of the time after reapplying power after a low volt cutout sequence (basically they hysteresis that keeps it off after the event kept working even after replacing the power!).

So.. now it works and it's awesome and perfect.. i've run my 1166 for well over an hour now at 12.6V.. and the 1160 before i melted it by accidentally applying 8V.. ran for more like two hours at 6.5-6.6V.. both of those are about 900 bulb lumens at that point... it was quite a sight to see.. you can get some idea from the pictures.. most of which the flash did not fire because of the bulb.

-awr

 

[andrewwynn]

every time i try to 'quote' somebody exploder crashes me dang it.. just lost a 30 min. post.

ok.. yes i looked into switcher chips.. but the LDO is so much more convienent.. for a bunch of reasons:

1) simpler to construct
2) fewer parts
3) far less in-line resistance.. important because many of my 'uses' are really for just holding back fresh bat voltage.. i.e. regulating 3LiONs to 10.8V like they are supposed to be.
4) no inductor or diode.
5) no RF noise

The primary benefit would be able to switch bulbs w/o switching battery packs.. that would be a very cool thing.. i've definitely and i'm sure i will continue to look into switcher solutions they are marvy.

I just 'fell in love' with the little LDO controller used here.. has everytihng a boy could want.. current regulation, voltage regulation, soft start.. low voltage cutout... i don't think it has thermal cutout or regulation..

The low volt cutout is an ABSOLUTE MUST since i use RAW cells or NiMH.. either of which over discharge is a no-no.

I have some really creative solutions of batteries and bulbs.. like a mag85 in a 2D host using 8 primary Lithium AAs... 900 lumens (bulb).. 54 min runtime... the best parts.. one-two punch.. 1) zero maintenance on the batteries.. so it can sit around for months w/o use.. and 2) like 36 hr estimated bulb life when only driven to the 9.87V required to get 900 bulb lumen! The other one in a simlar class is the 1160 run from 9 123s.. 863 lumen for 58 minutes.. in a 2D host.. primary cells.

I want to make some really nice hotwire lights for people that don't use their light daily or even necessarily weekly.. the light you leave on your night stand for instant access if you really need it but don't use it for daily chores, that sorta thing.

In any event.. 800-900 lumen (500-600 torch lumen) from primaries in a 2D host is doable.. just need the regulator to make sure that that resting 9V on the batteries doesn't get to the 5V 1160 bulb! under load the CR123A sags a LOT! 2.5V at an amp is the number i use for my calculations.. so.. 9 batteries is 3x3 or 9V resting.. but 7.5V under load.. looks like the 1111 would even be better.. could run that at about 900 lumen for about an hour from 3x3 Lithium 123 primaries!

-awr

 

[NewBie]

every time i try to 'quote' somebody exploder crashes me dang it.. just lost a 30 min. post.

ok.. yes i looked into switcher chips.. but the LDO is so much more convienent.. for a bunch of reasons:

1) simpler to construct
-awr

Definitely, essentially basic electronics.

2) fewer parts
-awr

Yes, and in trade, you burn up 4x or more power with your circuit

3) far less in-line resistance.. important because many of my 'uses' are really for just holding back fresh bat voltage.. i.e. regulating 3LiONs to 10.8V like they are supposed to be.
-awr

Somewhat less in-line resistance. There is one MOSFET and one inductor in line, during both phases of the switcher operation. So you use a nice N-Ch MOSFET at 0.003 ohms and a 0.0025 ohm inductor. Still the total is what, 0.0055 ohms? Again, your trade-off burns up the power, but yes, it is simple.

4) no inductor or diode.
-awr

Most modern switchers don't use diodes anymore anyhow. And you can get inductors with less resistance than MOSFETs. You are limited to how high you can go over the bulb voltage with your circuit, or you start burning some really serious power with your linear regulator. A buck switcher would convert the power, and draw less current from the batteries, which would reduce the losses in the batteries themselves.

In fact, if someone wants to run 9 cells with the 1185, it isn't much of a problem for the switcher, and you will utilize more of the cell energy, since you'd only be pulling 0.712 Amps out of them. At higher currents, the losses in the cells are greater.

5) no RF noise
-awr

Properly constructed, this isn't much of a problem anyhow. When folks were trying to constrain the circuit to fit in a 2AA Mag, trade-offs are made, which cause that problem.


Anyhow, consider it some day.

 

[andrewwynn]

already under consideration from the get-go.. i looked at several really neat switcher chips when developing this very circuit because i like all the benifits of switcher chips also, but i'll be able to make this one a lot sooner and with less grief.

In even the 1166 in 14.4V solution where there is quite a lot of power burned up on the FET.. efficiencies in the high 80s.. i'd be surprised to find one that can best that..

However efficiencies aside.. i like the idea of a buck/boost ckt that can run the likes of 1111 through 1166 from a 10.8V host etc.

that's a very interesting idea of using higher cell voltage to reduce internal resistance losses... but I wouldn't expect efficiencies higher than 90-92% in any switcher ckit like the type you are describing.

There is no way the case is closed on this subject.. just this round goes to LDO.

-awr

 

[NewBie]

that's a very interesting idea of using higher cell voltage to reduce internal resistance losses... but I wouldn't expect efficiencies higher than 90-92% in any switcher ckit like the type you are describing.

-awr

I'm currently holding in my hand, a stock eval board, which with no alterations and 25V input, I tested at 96% efficiency at 12V and 2A output, goes up to about 96.5% at 3.5A output, and 95.5% at 5A output. It matched the datasheet efficiency curves, within 0.5%.

With some tinkering, to optimize it for a particular output current, and spending an extra dollar on the inductor, I'm certain the efficiency could be pushed higher.

Not bad for a stock eval board.

True, linear regulators are always the simplest, and quickest to get working the way you want, with a very low level of complexity.

Good Job and Congrats!

 

[andrewwynn]

that's really awesome... i think the reason for the higher efficiencies ironcically.. higher current (the circuits i'm working with are always 1A because they are running LEDs).. when i get to 'round two' of the regulator for hotwire i will definitely explore the switcher version.. it would be so nice to have just one single battery and be able to run any bulb... can you try 14.4V input with 4A 6.5V output as well as 12.5V and 2A output?.. and what is the required overhead.. i.e. can i run 12.5V down to at most 14V input?

ps.. you type really well with one hand. (just teasin' cause you typed 'you are holding in your hand').

-awr

 

[NewBie]

that's really awesome... i think the reason for the higher efficiencies ironcically.. higher current (the circuits i'm working with are always 1A because they are running LEDs).. when i get to 'round two' of the regulator for hotwire i will definitely explore the switcher version.. it would be so nice to have just one single battery and be able to run any bulb... can you try 14.4V input with 4A 6.5V output as well as 12.5V and 2A output?.. and what is the required overhead.. i.e. can i run 12.5V down to at most 14V input?

ps.. you type really well with one hand. (just teasin' cause you typed 'you are holding in your hand').

-awr

You don't know the half of it... One hand has a 3/8" dia hole in it that was drilled about half an inch deep, ouch!

This particular one is not a 100% duty cycle version with the built in charge pump to keep the top MOSFET on for 100% of the time in an ultra low drop configuration. There are some controllers made for topside P-ch, which would not neet the pump, but it is harder to get the high efficiencies. I've got several controller/drivers that will do 100%, not sure where they are hiding, amongst thousands of parts right now. 94.1% at 15Vin with and output of 6.5V at 4A. At 15Vin, 12.5V at 2.5A out, 96%.

Even this could be customized and improved.

You could also do your own charge pump with a standard floating gate driver, and achieve the 100% duty cycle capability.

 

[andrewwynn]

as long as i can have full regulation i'm not concerned about a few % of efficiency.. The ability to pull the current from the batteries at higher voltage means the lower loss in the batteries will almost certainly counter the difference in efficiency..

lemme see how this would compare.. at 7.2V i'm pulling 1.2A out of the 17500 cells.. that's about 1.2C.. but if i can use a 14.4V solution in the same host.. means i need 8 15400 cells.. 27.6W (including converter loss).. means.. 0.96A.. or 1.27C... oh well.. I forgot need to use smaller batteries to get the higher voltage.. so i guess.. no improvement but not a big deal either... it would be of exceptional convenience to have one battery solution for all bulbs. I do favor bigger cells though.. so what about a buck/boost driver where i can use 7.2V to power a range of bulbs from 6V to 14V?

-awr

 

[NewBie]

as long as i can have full regulation i'm not concerned about a few % of efficiency.. The ability to pull the current from the batteries at higher voltage means the lower loss in the batteries will almost certainly counter the difference in efficiency..

lemme see how this would compare.. at 7.2V i'm pulling 1.2A out of the 17500 cells.. that's about 1.2C.. but if i can use a 14.4V solution in the same host.. means i need 8 15400 cells.. 27.6W (including converter loss).. means.. 0.96A.. or 1.27C... oh well.. I forgot need to use smaller batteries to get the higher voltage.. so i guess.. no improvement but not a big deal either... it would be of exceptional convenience to have one battery solution for all bulbs. I do favor bigger cells though.. so what about a buck/boost driver where i can use 7.2V to power a range of bulbs from 6V to 14V?

-awr

But a fella can grow the host, and take advantage of the lower cell loss and the higher efficiency of the switcher.

There are a few buck-boost parts that will maintain 90% efficiency over the range you mentioned, and one of them will do 95% on either side, pushing 98% at the crossover voltage.

Unfortunately, a boost increases the losses in the cells, as it draws more current from them to make the higher voltage. A buck is the opposite, the current goes down in the cells, increasing their efficiency.

 

[andrewwynn]

true but i'm stuck in a host.. so far i'm just making mods for mags.. so.. boosting voltage means using smalla batteries..

However i could see some neat possibilities including 3x 18650 in a 3C and bucking that down to run the 1111 for example.. you can hold it in overdrive to the likes of 900 lumen pretty easy that way.. whereas running from 7.2V it'll start there but quickly drop to 800 or so.

-awr

 

[NewBie]

true but i'm stuck in a host.. so far i'm just making mods for mags.. so.. boosting voltage means using smalla batteries..

However i could see some neat possibilities including 3x 18650 in a 3C and bucking that down to run the 1111 for example.. you can hold it in overdrive to the likes of 900 lumen pretty easy that way.. whereas running from 7.2V it'll start there but quickly drop to 800 or so.

-awr

But, can you fit 6x 14500 or 6x 18650 into a 3D? That could get you into the 2 hour runtime range, especially with the reduced losses in each cell, due to the lower current.

 

[andrewwynn]

can fit 9x 17500 in a 3D... you can fit 12 14500 in a 3D.. now that's a very interesting solution.. See.. with my LDO.. putting 1185 into a 14.4V solution is horribly inefficient.. oddly enough even so it's just as efficient overall as the 1154 which runs at 14V but is far less efficient in lumen/watt..

That would be a most excellent use of the switching driver.

What you can fit into that host is 12xR123 for 14.4V... you could also put in 12X NiMH... also for 14.4V.. at 35W and say 95% efficiency.. means you need.. only 2.55A from the cells vs 3.35.. that is not insignificant a difference.. very interesting though there.

In addition.. it would be nice for the primary based solutions like running the mag 85 from 12x 123 primaries.. which would be 12V no-load but 10V under load.

I will definitely be exploring 'version two' of the hotdriver in the form of a switcher.

-awr