How to use LM317T?

I have a robot on wheels that uses 7.2v battery. The battery runs it for good amount of time it is a 2000mah nimh vex battery. I want to supplement and charge it during peak hours. I bought 4 solar panel that can produce 2 V near my window and 3 volts outside. They produce 200mah at full sun. I want to series the solar panel up and have voltage regulator that can regulate it. I was told that the current also needs to be constant and so I ordered a LM317T. Here is the datesheet of lm317t How does the lm317t react when my solar panel hit shade and current goes under 200mah. What voltage should I put on my voltage regulator that I will connect to LM317T. Should I make it 10 V or 9 V? I really am new to this and want to use solar energy to charge my battery while it is connected to my robot in parallel. What current should be held constant to charge 7.2v 2000mah nimh?

Question by DELETED_MakiY2   |  last reply


Trouble with LM317?

Im having trouble in finding a heatsink for an LM317M chip and was looking for suggestions on where to find one that would be good for it. this is the datasheet for the chip...it should be the DCY Package (top view) http://www.ti.com/lit/ds/symlink/lm317m.pdf

Question by diabloboy   |  last reply


How to configure LM317T to deliver 5 amps?

Hi guys, I'm new to the site. I wonder if someone could help me resolve my problem. Well, I'm trying to build a Laptop AC Adapter, but I can't get these components right now: -A Transformer -A voltage regulator other than LM317T and I have no experience with other ICs. So I'm using a DC to DC converter. The input power supply is a Z12 Lexmark printer AC adapter. It gives a DC output current of 830mA under 30 volts (actually it's 37.5 volts, I've checked this with my multimeter). However, the output I would like to get is 4-5 amps under 19.5 volts. I would like to mention that I've already given it a try. But the output current I've got wasn't enough to feed the laptop. I've used an LM317T and adjusted the voltage with a 6.6k resistor and a 47k potentiometer down to 19.5 volts. If there is a way to boost up the current with a joulethief or using a set of transistors or parallels LM317Ts, please tell me. Also, I hope that you give me the part number of all the components to match up with the LM317T because I must use this type of regulator. Thanks for your help and please consider my situation.

Question by junkrecycler   |  last reply


Why do my lm317T and lm78XX regulators die so easily? Answered

While using my last 7808 voltage regulator as nothing more than a voltage reference for a breadboarded linear power supply design, I noticed that after a few small modifications, that the 7808 was no longer outputting 8V, and was instead floating 14.8V (kinda close to the +15V supply rail). At no point did the regulator overheat, and it was simply connected to the a 200K potentiometer to ground and a noninverting input of a LT1112. In the past, I have killed at least 3 LM317T regulators in my velleman 3-in-1 lab thingy, (it is a relatively simple circuit and was the first board I have ever fully reverse engineered.) The heatsink never did get too hot, but I used to always connect heavy loads to it that caused the overload lamp to come on. That LED was basically in series with a large resistor to the input of the LM317 so when the LED has enough bias voltage, it comes on when around 1A is being pulled. Anyways, I have killed countless other small 78xx regulators, one way or another, and even made some of them literally explode right away. (generally by getting the pinout wrong.) I blow up these regulators so commonly I even have video evidence lol! click to around 3:30 for the FAIL! https://www.youtube.com/watch?v=lPHHvVTVbwM So is it just me and my luck, or are these regulators which supposedly have all sorts of thermal protection, current limiting, and short circuit protection just not as rugged as they seem they should be?

Question by -max-   |  last reply


Adjustable Voltage on PSU ATX

I have an old Rockford P450.4 amplifier that I salvaged an LM317T and LM337T from. It also had some two (2) potentiometers that I salvages as well. I have a 400W Coolamx PSU ATX that I turned into a bench supply. I have read that people have been using these two (2) IC's to maintain a constant voltage through variable adjustment. I have seen several tutorials on instructables, but that all lack clarity, instruction and do not provide enough detail. I could really use a good tutorial, but have failed to find one of great interest.

Topic by bprins   |  last reply


Which Circuit Is Best To Use? Answered

I am trying to configure a LED circuit that allows me to charge 1.2v batteries using a solar panel. But i also want the solar panel to be used as a light sensor(detector) so during the day it charges..then at night the battery kicks in and lights up my LED strips. This is my first upgraded version using a schematic software.. Please help. Should i add 2 indicator LED's to let me know when the battery is being charged and when the battery is in use? I attached two images..one containing a LM317T and the other without. Just need some advice! Thanks

Question by islandboii242   |  last reply


How to make led lighting on your bike with a rechargeable battery?

Hi, I want to build led lighting on my bike with a 9V battery that charges all the time. so i made a diode bridge and added some capacitors, and i measured about 45V DC when i cycled down a hill. thats way too much current to handle for a 9 volt battery, so i got myself a LM317T, but at this point I'm getting a noob. i get confused when i see ground and the - pole. and i haven't worked allot with transistors, so can someone build a circuit for me where i have; - The diode bridge - The 35V 560uF capacitor - 1 Bright white led up front - 3 Bright Red led's at the back Thank you!

Question by ingkiller   |  last reply


Strangely behaving circuit, why? Answered

I have a circuit with a Lithium battery driving 12 same LEDs in a parallel setup. The circuit looks like this: http://i.imgur.com/FoBT5C0.png (also visible at the bottom of the question) The battery is charged to 3.8V and the LEDs have all around 2.73 forward voltage and they're rated for 20mA. According to my calculations the resistance should be much higher for the circuit to have 240mA (20mA*12) current but even with this low resistance the current is not enough. And that is what I don't understand. I even used this (http://ledz.com/?p=zz.led.resistor.calculator) calculator according to which I should use 4.7Ohm resistor. But even in my circuit with such low resistance I only get about 194mA. The other strange thing is that when I measure current flowing through one of the LEDs it's about 25mA which doesn't add up. 25*12=300 not 194. Where is the current coming from? And why is the current so low when the resistance is only about 1 ohm? Thank you for any suggestions. PS: I also tried using a LM317T in a current regulator setup but it didn't work either. The current was calculated to be 240mA but was much much lower and when I tried to use 5V power supply the current raised (which it shouldn't when using voltage regulator) but still wasn't 240mA.

Question by amdlo   |  last reply


Solar Panel Battery Charger

I'm doing a solar panel cell phone battery charger project for school using a 9V, 3.3W solar panel that I bought from here: http://www.ebay.com/itm/3-3-WATT-9-VOLT-SOLAR-PANEL-3-3W-9V-Monocrystalline-Solar-Panel-/130612072684?pt=LH_DefaultDomain_0&hash;=item1e691610ec (I can get around 8V under a light bulb and 10.5V under sunlight.) The circuit is shown in the picture with four, 1/4W resistors because the output is going to a USB cable. The regulator I tried at first was a 7805 from radioshack I noticed I was getting exactly 5V on the output, but only getting 1.5mA of current on the output of the regulator. I've tried the MURATA 78SR, Fairchild LM317T, N.S. LM1804IS, and a few others specifying 5V and 1-1.5A of current but I still only get 1.5mA of current on the output (I need at least 500mA). The phones I'm testing will charge, including a ipod classic, but I'm afraid that the 1.5mA of current is far too small and will damage the battery. I have yet to try using 3W or 5W resistors but I still don't think it would help, I'm also considering using a boost converter to get the current up (also the voltage) and then feed that output into the 7805. Am I doing something wrong? Can I get around 1A of output current from the 7805 by doing something else?

Topic by dan1133   |  last reply


Cree XL-M RGBW LED - recommended LED driver?

Hello I live in Australia and am new to the electronics world. I recently obtained a Cree XM-L RGBW LED 20mm 12W (image). I want to wire it up, so decided to browse the internet for wiring information. This has resulted in a multitude of questions and I haven't been able to find any answers.  From what I can gather, each LED runs @ 100% ~350 mA, up to a maximum of 1 A. Doing some research, it seems I should use an LED driver to ensure that a consistent voltage is maintained. I have some LM317T MOSFET/Voltage regulators coming in, but after some further reading, they can be inefficient. I read I can use an Arduino for PWM to help set different colours by varying the brightness of each LED. Can the Arduino also be used as a driver? Looking for a driver is where I'm stumped. I'm assuming I need a driver per LED. Does this mean I need 4 separate drivers or are 4 channel drivers available? I've seen some single-chip IC drivers and some larger (multiple component) drivers, which should I be looking for? I would have thought that drivers for this type of multiple LED would be easily found, but I'm stuck :) Maybe I'm searching for the wrong thing? I emailed Cree, but they simply gave me an email address for an Australian LED company that no longer exists (at least the domain is no longer active). So I thought the next best bet would be reaching out to users who may have dealt with these LEDs. Thanks!

Topic by hendrikse.alex   |  last reply