LM196 voltage regulator?

[cloudzy1]

Would this be a good choice to make a driver for 6 sst-90's? Any input would be appreciated.

 

[Norm]

:welcome:

Moved to Flashlight Electronics - Norm

 

[Mr Happy]

You have not provided enough information to answer the question. But can you even buy one? As far as I can tell, that part is not available.

 

[rushnrockt]

Same question as above, where are you going to get it? This is an old linear regulator, so heat dissipation will be an issue. If that is not an issue for your application, then you might be just fine, assuming that you'll know how to build the circuit.

 

[alpg88]

short aswer is no.

 

[cloudzy1]

What about a circuit that had a 7805 but also had a bypass transistor like a TIP3055 with proper heat-sinking

I'm trying to wire 6 sst-90 in series and i want to make the driver for it. It will be powered by a batteries any recommendations would be great.

The circuit I'm trying to base my driver on I found here http://www.rason.org/Projects/vreg/vreg.pdf

 

[Mr Happy]

Well now, the SST-90 costs about $30 retail, not including heat sinks and reflectors. You want to try driving six of them with a home-made circuit, and you don't know what you are doing. So you want to let the magic smoke out of $200 worth of parts so you can learn from the experience?

As for battery recommendations, I think the answer would be "a very big one". If you are successful at all you are going to have about 60 W of light that needs powering.

Have you thought of starting smaller and building up to the big stuff, learning as you go? It gets very frustrating when people with obviously insufficient knowledge ask how to build something really complicated and think there is some short cut that can magically be provided. I'm afraid there isn't. The way to drive an SST-90 is to learn how the driver is specified and then buy a ready made driver to the right specifications.

If you want to do something advanced and difficult like building a driver yourself you must go away and spend the time, however many weeks or months or years it takes, to learn how to do it. Sorry about that.

(By the way, the circuit you linked to is a voltage regulator, which is completely wrong for the job. For LEDs you need a current regulator. However, for that kind of power demand on batteries you don't want a linear regulator at all, you need a switching regulator. You can design one of those if you are an electronic engineer, otherwise you should buy one.)

 

[cloudzy1]

Thanks for the concern and safety of my wallet but that really isn't the issue here. I never asked for shortcuts or simplicity. http://talkingelectronics.com/projects/200TrCcts/images101-200/5A-AdjustableSupply.gif would that be a possible constant current driver? And by the way I think I'll stick around and learn form the people who are willing to share their knowledge. I'm an Aerospace engineering student so make it as complex as you want I'll be able to understand. Thanks

 

[MikeAusC]

Standard Linear Regulators like this have minimum of 1.5 volt loss across them, then an extra 0.5 volt across the 22 ohm resistor - that's 18 watts wasted if driving ONE SST-90. Give up now on this approach.

 

[Mr Happy]

Thanks for the concern and safety of my wallet but that really isn't the issue here. I never asked for shortcuts or simplicity.

I beg to disagree. That is exactly what you are doing in this thread.

http://talkingelectronics.com/projects/200TrCcts/images101-200/5A-AdjustableSupply.gif would that be a possible constant current driver?

No, it wouldn't. Those supplies are adjustable voltage supplies without current regulation. LEDs need a supply with current regulation, not voltage regulation. A circuit similar to that could be extended and changed to include current regulation, but that would be the wrong way to go as Mike R points out.

And by the way I think I'll stick around and learn form the people who are willing to share their knowledge. I'm an Aerospace engineering student so make it as complex as you want I'll be able to understand. Thanks

That's great. Please do. But why not start at the beginning with reading up on the characteristics of LEDs and how to follow an LED datasheet, then building a simple circuit to power a standard 5 mm LED of different colors and making sure you understand how that circuit works? Then extending to more LEDs and bigger LEDs in stages. Coming along and asking how to make a driver for 6 SST-90s powered from batteries is like going to NASA and asking "How can I build a rocket ship to take me to the moon?"

Very few people actually build drivers for that sort of job from scratch. What nearly everyone here does (except for people who manufacture and sell modules) is search around for a ready made driver with the right specifications and purchase that. Two reasons for doing so are that the purchased driver may work better, and that purchased drivers may use parts that are very hard to obtain any other way.

 

[cloudzy1]

I'm sorry for being stubborn but is this circuit more applicable if I modify it for my input output voltages and amps. http://cds.linear.com/docs/Application Note/an30fa.pdf its on page 22 fig.34 and it is a switch regulator.

 

[MikeAusC]

At these power levels a switching regulator is the only viable option.

To drive LEDs you need current regulation - not voltage regulation.

 

[Mr Happy]

I'm sorry for being stubborn but is this circuit more applicable if I modify it for my input output voltages and amps. http://cds.linear.com/docs/Application Note/an30fa.pdf its on page 22 fig.34 and it is a switch regulator.

Not exactly. It is a voltage regulator, not a current regulator. You are missing the most important fact, that LEDs are driven by current not voltage. Try looking for LED driver circuits instead of voltage regulator circuits. You will likely turn up more relevant results. That application note dates from 1989, which is more than 20 years ago. It will not have LED driver applications because high power LEDs did not exist back then.

 

[VegasF6]

I have never built and designed my own switching regulator so I can only be of limited help here. It really is a very big project you want to take on :)
I am partial to National Semiconductor. I would suggest you visit their website and sign up for the web designer tools. Pretty darn useful. Take a look at the "simple switcher" line for one. And what they simply label "buck converters."

For this much power you are more than likely going to be using a buck circuit as I just can't imagine using a boost circuit. So, expect at the minimum a ~20v battery pack and I would think at LEAST 3AH cells. Perhaps a 6x18650 pack using Panasonic 2900 cells. Or nickel based, maybe some nice nimh D size. Or lead acid. It depends on your plans of course. Whatever you finally do, please take the time to read up on proper care and charging of your battery as well. In particular with lithium cells there is a very real potential for a LARGE explosion.

I don't know if this is a light you really need built or simply an exercise to see if you can do it, but either way, let me suggest you purchase a ready made driver. Please take a look at the fine products offered at www.taskled.com spend ~ $50 bucks or so and get a decent product. Then from there you can choose to sort of "emulate" that design if you still feel the need to build something. In the case of those drivers I mention, besides the power handling and current regulation, they incorporate different power modes, perhaps flashing or strobing, temperature monitoring to protect itself and the leds etc. Anymore discrete components are only a small part of the equation, you really must be able to program and use a micro-controller. Well, maybe must is a strong word, but it sure helps.

 

[Th232]

Having built a switching regulator, here're a couple of tips:

* Follow the recommended layout on the datasheet.
* Learn why they recommend certain inductors/caps.
* Use common (electronics) sense. Like why the high current paths should be kept short and fat. This may need to be balanced with what the recommended layout says and other restrictions you have (e.g. single sided vs double sided PCBs).

For someone who already knows electronics, how to follow the datasheets correctly and how to design/make their own PCBs, making a switching regulator is easy, if slightly tedious...

...making an efficient one is a lot more painful.

If this is purely educational, go for it, I certainly learnt a fair bit (it was also costly). If this is for a light you're going to use a lot, please consider just buying a driver. Especially if it's an important one.

 

[cloudzy1]

I have never built and designed my own switching regulator so I can only be of limited help here. It really is a very big project you want to take on :)
I am partial to National Semiconductor. I would suggest you visit their website and sign up for the web designer tools. Pretty darn useful. Take a look at the "simple switcher" line for one. And what they simply label "buck converters."

For this much power you are more than likely going to be using a buck circuit as I just can't imagine using a boost circuit. So, expect at the minimum a ~20v battery pack and I would think at LEAST 3AH cells. Perhaps a 6x18650 pack using Panasonic 2900 cells. Or nickel based, maybe some nice nimh D size. Or lead acid. It depends on your plans of course. Whatever you finally do, please take the time to read up on proper care and charging of your battery as well. In particular with lithium cells there is a very real potential for a LARGE explosion.

I don't know if this is a light you really need built or simply an exercise to see if you can do it, but either way, let me suggest you purchase a ready made driver. Please take a look at the fine products offered at www.taskled.com spend ~ $50 bucks or so and get a decent product. Then from there you can choose to sort of "emulate" that design if you still feel the need to build something. In the case of those drivers I mention, besides the power handling and current regulation, they incorporate different power modes, perhaps flashing or strobing, temperature monitoring to protect itself and the leds etc. Anymore discrete components are only a small part of the equation, you really must be able to program and use a micro-controller. Well, maybe must is a strong word, but it sure helps.

thanks for the input. if I fail at making this driver which apparently I will LOL, Ill buy a driver but I'm definitely going to try and make one first. As for micro-controller programing I have descent experience with that.

 

[VegasF6]

Well good luck with it. Part of the challenge is size. If you are building this thing on a breadboard and with components that normal human beings can solder, than cool! If you are trying to build something tiny to fit in a flashlight and with .1mm pitch and 30 pins, I shudder to think about that!

Here is a very cool home made light of proportions that man can actually handle.
http://www.candlepowerforums.com/vb...Rebel-LED-flood-light-with-red-and-cyan-boost
It's just a very simple transistor based circuit, nothing complicated but excellent results.

 

[cloudzy1]

I cant find a constant current switch regulator that will handle the 9A, so i was thinking of building the driver with this, LT3743, good up to 20A but it needs PWM, which I can do but just want some opinions or possibly a more reasonable choice.
thanks

 

[cloudzy1]

Well good luck with it. Part of the challenge is size. If you are building this thing on a breadboard and with components that normal human beings can solder, than cool! If you are trying to build something tiny to fit in a flashlight and with .1mm pitch and 30 pins, I shudder to think about that!

Here is a very cool home made light of proportions that man can actually handle.
http://www.candlepowerforums.com/vb...Rebel-LED-flood-light-with-red-and-cyan-boost
It's just a very simple transistor based circuit, nothing complicated but excellent results.

that is cool I'll have to take that into consideration

 

[Mr Happy]

I cant find a constant current switch regulator that will handle the 9A, so i was thinking of building the driver with this, LT3743, good up to 20A but it needs PWM, which I can do but just want some opinions or possibly a more reasonable choice.
thanks

If you carefully match the supply voltage to the LED emitter (e.g. a lithium ion cell has an operating voltage of about 3.7 V on average) you might get away with a simple linear regulation scheme like the one in the thread VegasF6 linked to. The problem with linear regulators in general is that they tend to waste power and need plenty of cooling. This doesn't mean you can't use them, but it is often undesirable in mobile battery powered devices.