How to get 32Volts from 28.8 Volts

Hello, im a total noob!
Can anyone show me how to get 32 volts from 28.8 volts?

Ive looked at the LM317, but that just gives you any voltage lower than the one you have, i need to boost mine!
I just need the simplest circuit schematic!
Cheeers!

What current you need for the output ?. LM317 is just a regulator and will definitely regulate lesser than the Input. An SMPS will suite you.

You can check the MC34063

**broken link removed**
MC34063A design tool
MC34063 DC-DC calculator

Alex

Hey Dude!
Hi
You can use from multiplier with diode and capacitor and then use from LM317 for your desired voltage!
Best wishes
Goldsmith

Im liking this 34063 chip, very useful thing to have! i get the calculations, and i have the values, but there are a few things about the schematic that i dont get, as i am a total noob...
As i get it, whehre it says Vin i connect the negative terminal, but im not getting where i plug in the positive terminal of my battery pack... is that my ground ? do all the ground connections on the diagram indicate connections to the positive terminal ? if no, what do i connect them to ?
you see, im a total noob


Here is the diagram **broken link removed**

The input is shown as Vin at pin6 (positive) and the ground (negative)

Alex

aaah ok
so i conect the positive terminal to Vin and all the ground leads to negative terminal!
im so clueless, thank you!

---------- Post added 07-11-11 at 00:19 ---------- Previous post was 06-11-11 at 23:10 ----------

Raza said:

What current you need for the output ?. LM317 is just a regulator and will definitely regulate lesser than the Input. An SMPS will suite you.

Click to expand...

i want to connect 3 series of LED, each drawing 20mA, so i guesthats 60mA total.
I might go with the 34063 switching regulator and an LM317 to further stabilize the current, as i probably wont be capable of fine tuning the 34063.


on another note, ive come across another problem, coz im a noob,
i see an inductor in the schematic, but ive no idea what kind it is, when i search the web i get all sorts of wierd results... any help would be greatly appreciated!
If you can give me links for the parts i need, that would be the best!
here are the specs i got:
Ct=46 pF
Ipk=136 mA
Rsc=2.213 Ohm
Lmin=235 uH
Co=12 uF
R=180 Ohm
R1=1.1k R2=27k (31.93V)

Cheers!

When designing such circuits (that is: the ones parameters of which depend heavily on component values) you need to calculate desired values, then find what closest values you can get, and then enter those found values into calculation program to check if parameters of circuit don't change. I think first you need to consider inductors, as they are usually most expensive and least accurate, then capacitors, and resistors at the end, because they are the cheapest and come in widest value range.

What those value that you posted mean is shown on circuit diagram in the calculator.
Ct is the capacitor which sets oscillator frequency. Higher frequency desired = lower capacitance
Ipk i think is the peak value or current being switched. IMO this is listed because it sets the minimum current rating of the inductor
Rsc is probably the shunt resistance for measuring current (and probably also limiting it)
Lmin is the minimum inductance of the inductor. Higher frequency = lower inductance needed, lesser physical demensions of inductor
Co is the filtering/tank capacitor value. Again: higher frequency = lower value for given parameters
R, R1 and R2 are values of resistors used for voltage sensing. I think you can replace R1 and R2 with a precision potentiometer to get tighter control of the voltage

Current Plays vital role in this Conversion.....I think first check the load current that you are expecting from the 28.8 volts then you can chose ...regulator or even potential devider network with capacitor parallel to ....kindly please note that you need to choose the resistances of the potential devide network based on current rathing of your load .... It is very simple KVL based approach but need you need to have proper current rating of the component to work.....also you need to think of how much time you want hardware to be on ......as in case of potential devider approches.....there is by default power loss......

with regards,

Milind

I repeat my question as in post #2. What is your expected current ?

i want to connect 3 series of LED, each drawing 20mA, so i guesthats 60mA total.
I might go with the 34063 switching regulator and an LM317 to further stabilize the current, as i probably wont be capable of fine tuning the 34063.

Click to expand...

LEDs are generally operated with constant current rather than constant voltage. Are you sure about the minimum and maximum expectable LED series voltage at 20 mA? It will be temperature and type dependent as well. If efficiency is an objective, you would try to operate the LEDs with the switched mode converter without a linear post regulator. 34063 is one of the cheapest switched mode controllers available on the market, but not particularly high performant or convenient for the designer.

I repeat my question as in post #2. What is your expected current ?

Click to expand...

I heard 60 mA in post #7.

ooooops I am sorry I overlooked it. I agree for the 340xx series. FvM thanks for opening my eyes for my mind.

Well i guess there are alot of factors to consider, i was thinking of perhaps attaching a small fan to cool the box with the LED's , but im determined to use the 340xx series, its something i get, and learning another thingy... i dont have the energy
I want the devide to work for an hour, i dont care if it works longer. I just have one more question: Is it more efficient to step up the voltage of run a larger number of series for the 30 LED's straight from the battery?

would you like to tell us the source of 32 volt...........

qayyoum said:

would you like to tell us the source of 32 volt...........

Click to expand...

Already mentioned in post #5

but im not getting where i plug in the positive terminal of my battery pack...

Click to expand...

Alex

How to test LM317T (voltage regulator) ?

thanks

im going to be using 3 9V alkaline Duracell MN1604. Im considering using more heavy duty batteries in the future, i want to see how long these 3 will last.
there are a bunch of schematics for a voltage regulator circuit online ( using the LM317T), and there is a tool to help you calculate the resistor values for your voltage - ive seen a few tutorials about it, and it seems to me its a good idea to usa a variable resistor in there, so that you can fine tune the voltage output. it was only after all that, that i realized that it doesnt give out more voltage than you put in, you need atleast 1,5V more than you want to output, but it does provide a stable source. There is also a formula to see if you need a heatsink, the greater the voltage difference between input and output, the more heat the LM317T will produce.

My question is still: is it more efficient to step up the voltage and do 30 leds in 3 series, or to do it directly from the battery pack (28.8V= 9LED is 1 series) with 5 series? Cheers

To step up or not to step up 28.8V to 32V

im building an LED light, using 3 9V batteries, 28.8 volts total. ill be using 30 LED's , Vf=3.2V 20mA
My question is: is it more efficient to step up the voltage and run 3 series of 10 LED's, or to not step up the voltage and run 3 series of 9 and 1 series of 3.

Cheers!

The question is still related to the same problem, I don't see a reason to ask it in a new thread.
Threads merged [alexan_e]

Click to expand...

Re: To step up or not to step up 28.8V to 32V

I suggest a trial run, by putting 3 strings of 3 led's on one new 9V battery. That makes 9 led's.

They'll be bright for a short while. The battery must provide 3.2 x .02 x 9, equals .576 watts.

This is substantial drain on those 6 small cells. It won't be long before the battery has gone down to 8 V or so. The led's will get dim.

LED's have a relatively narrow operating range, voltage-wise. With a new battery they tend to get overdriven. The logical move is to put in a current limiting resistor inline. It wastes a small amount of power.

After operating a while the battery is low by just a volt or so. The led's are dimmer. Now you wish you could take out the resistor.

That's how it is with LED's.

Of course the better solution is a current source. It's like a variable resistor automatically feeding the led's 20mA whether the battery is at 9V or 8 or 7.

However as long as you bring in the idea of using long led strings, it should be possible to make a step up converter that has current limiting built in. Even if only in the form of what the 9V battery can provide as short current bursts.

It could be coil based or capacitor based. The capacitors might be small values, etc.

In any case you might have to reduce the total number of led's.