Constant current for LED light

[Norm]

Being a little short on electronic know how a thought
that I've tried in various steps except for the hoist...
thanks for looking
Norm.



(fixed it, G-)

[Norm]

sorry the print is too small

[Fused]

What are you building Norm?
Whats the purpose for the LED light?

  I cant figure it out.

Looks like your having fun any way.

Good luck!
Happy Holidays

Fused

[richhagen]

Hi Norm, It is an interesting method of trying to drive an LED while limiting current.  If the stepper motor is properly selected it would likely work to some extent as the output from the stepper would be limited.  The light would flicker out at the top and bottom as the motor stops to change direction, and the whole thing has a few mechanical parts, the failure of any one would cause the light to fail.  What current are you aiming for and approximately what voltage?  

By the way, the batteries that you built from the bruce packs are all installed over in the Philippines, and at some point Bruce or I will post a story on that trip.  We got 41 kits there, and installed about 23 of them that we were able to get through in our limited time, we had our trained team of local installers install the last few save one, to ensure that they could get the rest of them up without our intervention.   Jerrick, our guide out in the boonies, wrote me that the remaining 18 have mostly been installed at this point.  Rich

[Norm]

Rich: Here is a clearer sketch....

when the car suspended by the pulley connected to the stepper motor
runs downhilll and almost reaches the bottom the cable moves and
brings the car up faster than it is rolling downwhen the car hits a top
limit switch the cable stops allowing the car to roll down to almost the bottom
until it hits the bottom limit switch.
the car with the stepper motor rolls downhill continuously giving a constant current.
....Guess I'll have to make a model.....

BTW I really enjoyed making those batteries alto they didn't turn out as nice as
I wanted them too.  Thanks for letting me participate....gave me a good feeling

[richhagen]

The reason I asked about the current an voltage you were looking for for the light is that I am making another batch of those lights I made for the trip, and one of them will have your name on it.  They are 12V, and I can adjust the current from zero to about 700mA or so.  The ones we took to the philippines had a range of about 350 to 400 mA of draw basically because of component tolerances.  These use a driver based on Commanda's design from her 'Master Class' series of posts.  I can also post you one of those driver circuits if you let me know what you are aiming for in terms of current and voltage.  I already have a few assembled, and can just change a component or so based upon what you wish for.  Rich

[Bruce S]

Rich;
 good seeing you back on here. Still sorting pictures here at work and at home.
WOW did you take some awesome pics! Hooked little notebook up to 32" LED TV and boy do they really shine!!
Glad to see Jerrick and all were able to get the rest installed.

Norm;
  Rich is very correct on the batts; they worked out very well. After the New Year, I will be able to get the battery tester back online to start the next batches.

Rich's light is a very durable one, even the one that's been in a wood smoke filled environment still works. Can't seem to find the pic of the encrusted one from 2009 trip, but it was still working.

Cheers!
Bruce S




 

[Norm]

The reason I asked about the current an voltage you were looking for for the light is that I am making another batch of those lights I made for the trip, and one of them will have your name on it.  They are 12V, and I can adjust the current from zero to about 700mA or so.  The ones we took to the philippines had a range of about 350 to 400 mA of draw basically because of component tolerances.  These use a driver based on Commanda's design from her 'Master Class' series of posts.  I can also post you one of those driver circuits if you let me know what you are aiming for in terms of current and voltage.  I already have a few assembled, and can just change a component or so based upon what you wish for.  Rich

Rich....excuse me for not answering right away so I'd like one that uses one of the 2.6 amp/hr. batteries where the light will
last from dusk till dawn. about 8 hrs. at least.
The lights that I have do that....I am gradually getting the idea WHY a driver circuit is needed for LED lights....ta dah !

[richhagen]

I've been toying with the idea of adding another switch to a few of those lights to give it two stages of brightness.  Basically taking the resistor that determines the current and paralleling two resistors in its place, one through a second switch.  In that way you could through that switch and change the resistance, which would in effect allow you to set up two current (or brightness) settings.

A 2.6 Amp hour battery discharged half way is 1.3 amp hours, and divided by 8 hours yields 162.5 mA draw.  The lights as they were built for the trip drew more than double that current.  They would draw less current and the light would stay lit a bit as the voltage of the battery dropped, but the battery would be mostly depleted at that point already. 

I will make one in the next batch with a switchable current between a full bright setting of about 375 mA and a lower light setting which I will target near your 163mA goal.

Rich

[Norm]

Thanks Rich.....
  I get to messing with lights and my head starts spinning.....so many different ways.
I have one $1 flashlight takes 3AAA alkaline or carbon zinc gives a bight pale blue light 3LEDS
another$1 one has 9 LEDs better more white also with 3AAA.
Either one works good as long as you use the alkaline or carbon zinc for which they were designed
but you start using rechargable batteries....of course whole new ball game .
 Looking forward to the light.

Norm

[Bruce S]

Rich & Norm;
  During the tests with one of the lights way back while covering nights. I found that because of the voltage holding abilities the 2.6Ahr battery would easily keep the light at full brightness for a good 6hrs+. at about 7 hours of being on, the light would begin to dim just a bit, but the light would stay on 9 hrs.
At 9hrs it was pretty easy to look directly at the LEDs unlike it when the batteries are fully or even 1/2 charged.

Rich I have my test 2.6Ahr battery still here in my office if you need one sent to you.

Cheers
Bruce S

PS>> No luck so far on getting the seeds to sprout, but the other pepper plants LOVE the light 

[Norm]

 When you get right down to it....those LED bulbs for 2 cell
flashlights were the best weren't they Bruce? You know whose
I mean don't you ? Don't want to mention any names in case
he's sold out...I'd get chewed out up one side and down the other !
Most people didn't seem to appreciate them .....2 'D' batteries would
last 6-8 hrs. a day for nearly a month...cheap batteries at that.
I guess they kind of spoiled me for any other type LED bulbs...
Norm.

[rossw]

A 2.6 Amp hour battery discharged half way is 1.3 amp hours, and divided by 8 hours yields 162.5 mA draw. 

Just in case nobody ever told you this.... a 2.6 amphour lead-acid battery CANNOT gives 2.6 amphours for any significant number of cycles.

If you're planning on discharging and charging daily for a year or more, you really want to limit the depth of discharge to no more than 10 or 20% of the batteries rated capacity. "Deep cycle" cells can usually discharge to 80% a few hundred times. Normal duty cells can make it perhaps a few tens of times.

If I didn't read back far enough, and you're using LiFePO4 or similar technologies then disregard my comments

[Bruce S]

A 2.6 Amp hour battery discharged half way is 1.3 amp hours, and divided by 8 hours yields 162.5 mA draw. 

Just in case nobody ever told you this.... a 2.6 amphour lead-acid battery CANNOT gives 2.6 amphours for any significant number of cycles.

If you're planning on discharging and charging daily for a year or more, you really want to limit the depth of discharge to no more than 10 or 20% of the batteries rated capacity. "Deep cycle" cells can usually discharge to 80% a few hundred times. Normal duty cells can make it perhaps a few tens of times.

If I didn't read back far enough, and you're using LiFePO4 or similar technologies then disregard my comments

RossW: No worries you are absolutely correct with due regards to LA based batteries,
                                                      MY bad for NOT making sure the NiCd symbol was inserted here.
Norm < the NiCd rebuilder guru> helped Rich Hagen & I with rebuilding some 18V 1.3Ahr batt packs < NTL labeled as bruce_packs> using these we rebuilt them into 12V 2.6Ahr & 3.9Ahr packs for our trip to the Banaue Region in the Philippines. There was a post in the old forum of some of the posted testing I did with the 3_LED 3Watt light Rich built using Commanda's circuit from her master class and both the 3.9 & later 2.6Ahr NiCd batteries.

Cheers;
Bruce S
We are both trying write up more than the little post I did back around the first of December.

[Bruce S]

When you get right down to it....those LED bulbs for 2 cell
flashlights were the best weren't they Bruce? You know whose
I mean don't you ? Don't want to mention any names in case
he's sold out...I'd get chewed out up one side and down the other !
Most people didn't seem to appreciate them .....2 'D' batteries would
last 6-8 hrs. a day for nearly a month...cheap batteries at that.
I guess they kind of spoiled me for any other type LED bulbs...
Norm.

I know the secret you speak of and don't tell the internet, but I still have one in it's original shipping, hoping that is a short while I too can become a dozen aire by selling it to the highest bidder 
I agree those buggers due make even rechargeable batteries last a long time.

I do wonder if <HE> has any left 

[Norm]

Maybe we should ask <HIM> LOL !
I have one flashlight with 'D' cells that I only use occasionaly....
I put new cells in it.....3 or 4 years ago cheap ones ...4 for a $1
how long they last only depends on the shelf life in this instance
I tried it a little while ago light is just as bright as if I just put them in....
1.46v each battery DG heavy duty?
the other is one I use every day several times using your little yellow AAs
I recharge them like once a month....
Norm.

[ghurd]

The last time <he> looked,
he only had somewhere around 600 left?

Not really flying out the door anymore. 
They are a hard sell now that HF regularly gives
away those little 3-AAA 9-LED flashlights... for free.

[Bruce S]

The last time <he> looked,
he only had somewhere around 600 left?

Not really flying out the door anymore. 
They are a hard sell now that HF regularly gives
away those little 3-AAA 9-LED flashlights... for free.

Well Dang if I knew he had 600 left I'd be doing a little horse trading.

Just think what a PVC tube with some reworked NICds would work out . Might even be some real cool gifts for next Christmas 
Being that they're already setup for 6Vdc those B_packs single sticks are already perfect for wiring up a simple switch on the end.

Just thinking out loud 

[Norm]

The last time <he> looked,
he only had somewhere around 600 left?

Not really flying out the door anymore. 
They are a hard sell now that HF regularly gives
away those little 3-AAA 9-LED flashlights... for free.

Yeah wonder what they do with them when the batteries
are shot....(yeah get another free one)
these don't work so good if you want them to last for 6 hrs.
every night for a month at a time 'tho.
 What a nice windup flashlight with one of your bulbs would be
or solar powered? Well in fact....I do charge up those little
yellow batteries with a small solar cell and use in the small
flashlight with one of your bulbs

[Norm]

Bruce....See ? Like I said.....maybe we should ask <him> LOL !
Norm.

[zap]

<He> does know <his> stuff when it comes to low power stuff!