1. Change the current of LED only using 16 mA then the total current is I = 16 mA * 21 = 336 mA.
2. Change the regulator to LM2576-05.

 

1. Change the current of LED only using 16 mA then the total current is I = 16 mA * 21 = 336 mA.
2. Change the regulator to LM2576-05.

Building a switching supply will be beyond the capabilities of the SP. SP can't just simply swap out the part, there will be additional supporting components.

Something like this

http://www.ebay.com/itm/1pcs-LM317-...040029?hash=item3aa5ef815d:g:KkEAAOSwEeFVEiw4

Would be a better solution.


One of those car USB chargers could probably be hacked in a pinch.

 

Hi.

Don't need the transistor with a LM317T and 420ma load.
See attached.

 

Building a switching supply will be beyond the capabilities of the SP. SP can't just simply swap out the part, there will be additional supporting components.

Something like this

http://www.ebay.com/itm/1pcs-LM317-...040029?hash=item3aa5ef815d:g:KkEAAOSwEeFVEiw4

Would be a better solution.

One of those car USB chargers could probably be hacked in a pinch.

If the TS take the suggestion then the current will be reducing to the crossing line as normal heat, then using LM317 is one the option, otherwise if still using the LM317 then the heat will be still there.

The circuit of LM2576-05 is not that complicated, otherwise I won't given the suggestion.

 

If the TS take the suggestion then the current will be reducing to the crossing line as normal heat, then using LM317 is one the option, otherwise if still using the LM317 then the heat will be still there.

The circuit of LM2576-05 is not that complicated, otherwise I won't given the suggestion.

Agreed...an SMPS would be a better choice...

 

Agreed...an SMPS would be a better choice...

And there are some LM2576-05 products already made and they can be found on ebay.

 

The circuit of LM2576-05 is not that complicated, otherwise I won't given the suggestion.

Completely agree that those TI chips are wonderful in their simplicity. But I still say built, off the shelf will be a better choice in this case.

 

Completely agree that those TI chips are wonderful in their simplicity. But I still say built, off the shelf will be a better choice in this case.

We just given ideas, let the TS do the choice.

 

I have small project where I used a power supply supplying 15Vdc wired to LM318T to output 5.1Vdc. I am trying to drive a load of 21 LEDs. Each LED is wired in parallel with 100 ohm resistor. I was trying to "turn on" the load with a transistor hook up with a photo-resistor so it turns the LEDs on at night. By my calculations: 3.2V with 100 ohm resistance = 19mA = ~20mA. Load total = 20mA x 21 = 420mA. P = 3.2V x 0.420A = ~1.3W. The transistor is 1300d. I hooked up 100 ohm resistor to same 5.1V supply to the base of the transistor. The load is between the 5.1V supply to the collector. Emitter to ground. The LM318T begins fine but then begins to heat up rapidly. I do have the LM318T mounted to a heat sink. Is it suppose to get really hot? Did I miss calculate?

Hello
1)i think that if you use lm338 replace lm318t. its best. becuase you can use heatsink .
2)or maybe your lm318 is devastated
3) you sure .know that each led has 20ma current.

 

Hello
1)i think that if you use lm318 replace lm318t. its best. becuase you can use heatsink .
2)or maybe your lm318 is devastated
3) you sure .know that each led has 20ma current.

Are you missing something?

 

Or use a HEATSINK!

 

Hello
1)i think that if you use lm318 replace lm318t. its best. becuase you can use heatsink .
2)or maybe your lm318 is devastated
3) you sure .know that each led has 20ma current.

I suggest you re read the thread carefully.

 

I have small project where I used a power supply supplying 15Vdc wired to LM318T to output 5.1Vdc. I am trying to drive a load of 21 LEDs. Each LED is wired in parallel with 100 ohm resistor. I was trying to "turn on" the load with a transistor hook up with a photo-resistor so it turns the LEDs on at night. By my calculations: 3.2V with 100 ohm resistance = 19mA = ~20mA. Load total = 20mA x 21 = 420mA. P = 3.2V x 0.420A = ~1.3W. The transistor is 1300d. I hooked up 100 ohm resistor to same 5.1V supply to the base of the transistor. The load is between the 5.1V supply to the collector. Emitter to ground. The LM318T begins fine but then begins to heat up rapidly. I do have the LM318T mounted to a heat sink. Is it suppose to get really hot? Did I miss calculate?

Yes, LM318 is wrong. LM317 would work. What is the transistor for?

 

Looks like the load is well known and constant. Why not use a resistor ahead of the LM317 to drop Vin to just above the drop out voltage needed to power the leds and let the resistor dissipate most of the power? Probably still need a heatsink though.

 

Yes, LM318 is wrong. LM317 would work. What is the transistor for?

lm318 can give voltage and current more than lm317.please read data sheet

 

lm318 can give voltage and current more than lm317.please read data sheet

Are you missing in the jungle?
Have you read carefully for all the posted and you asked other member to read the datasheet, have you ever check the datasheet, do you know what is LM318 and what is LM317?

 

Are you missing in the jungle?
Have you read carefully for all the posted and you asked other member to read the datasheet, have you ever check the datasheet, do you know what is LM318 and what is LM317?

yes

 

yes

Ok, then what is LM318 and what is LM317, what's the difference between LM318 and LM317 and their purpose of design?

 

Sounds familiar. Doh!

I like the episode where Homer became the fat guy working from home.

He set up a novelty bird ornament to hit the vent reactor button - which fell over. (that might actually be the same one).

 

Ok, then what is LM318 and what is LM317, what's the difference between LM318 and LM317 and their purpose of design?

ohh. Excuse dear scott. i want to say you. use LM338 no LM317. please read datasheet LM338 and best for you. my powersupply is by LM338. again Excuse very much.i upload its datasheet for you.it can give to you high current and voltage. and you can seting voltage by file.