Tagged Questions

1
vote
1answer
112 views

Keeping the output of a heated LM317 constant

I have built a power supply using an LM317: simulate this circuit – Schematic created using CircuitLab When the supply is on for a rather long time (several hours) with a respectable ...
4
votes
2answers
207 views

Power Supply Diode Keeps Burning Out

I am trying to replicate the circuit I found here: This is a photograph of what I have built: In my photo I have labeled one diode in the bridge rectifier which has burn out twice now. ...
1
vote
1answer
150 views

Using a 12VAC Transformer For a LM317T Power Supply

I have found a circuit diagram for a regulated power supply using a LM317T regulator which I wish to build as my first electronics project. The only problem is that instead of a 24 VAC transformer ...
3
votes
1answer
869 views

What use are the transistors in this (LM317 based) power supply circuit?

I am looking to do a small bench power supply project and am studying various designs based around a LM317. Basic I know but I still seem to manage to have have some questions. Fig 22 on page 8 of ...
2
votes
2answers
2k views

Add on/off indicator LED to circuit

I'm working on my first small electronics project; building a small LM317 based power supply. I've built the circuit as shown in the data sheet (black part of the circuit diagram below) on a ...
1
vote
3answers
424 views

LM317 Ground Problems

I have a LM317 setup as a 3.3V regulator. I am getting 12V input from an Agilent Technologies E3631A Variable DC Power Supply. On this same board I also have a LM7805 regulating to 5V. All of my ...
3
votes
1answer
799 views

LM317 current limiter, driving with uC

I am somewhat confused on how the current limiter configuration works with the LM317. It's configuration looks as so: Datasheet: http://www.ti.com/lit/ds/snvs774l/snvs774l.pdf The formula given is ...
1
vote
1answer
2k views

Dual polarity vs dual rail power supply

My previous post turned out to contain too many questions, so I'll focus on the main one first, and figure the rest out as needed. I'm looking at building a DC lab power supply, roughly 1.2-14 volts ...
6
votes
4answers
973 views

LM317-based adj power supply output takes a while to stablize

I recently built-up a quick little LM317-based adjustable power supply schematic: However I've noticed the output can take several seconds (on the order of 10 or so) to "settle down" after turning ...
3
votes
2answers
2k views

Is this 7805-based design correct?

I found this design on internet: It is said to be a regulated power supply with variable DC output 5-15 V, 400 mA. My first question: Is this design around 7805 correct? I am asking because it ...
2
votes
2answers
2k views

LM317 Heat sink, how big?

Thanks to the help of a few of the other guys I have my AC to DC rectifier working, and the rest of the power supply working. Now while testing the power supply, my 18V AC transformer gets rectified ...