LEDs installation

[livehho]

I need to install some 12VDC LEDs on my dash to monitor the liquid level of the reservoir, circuit breaker, etc.. and wanna put a voltage regulator right before the LEDs so that they won't burn out in less than a week because of the fluctuating voltage of the car.

I was recommended a LM2937 voltage regulator (http://www.national.com/ds/LM/LM2937.pdf).

'Ideally suited for automotive applications, the LM2937 will
protect itself and any load circuitry from reverse battery
connections, two-battery jumps and up to +60V/−50V load
dump transients. Familiar regulator features such as short
circuit and thermal shutdown protection are also built in.'

The data sheet also recommends a low ESR capacitor (below 3Ω)

Are these two components all I need to make my circuit or there are more? like resistors and diodes

sorry if this question sounds stupid.. i'm new to electronics

Also, if somebody has a link to a schematic would be great.

[ridelong]

The LM317 is an excellent choice, I've used them many times.

If you get on the National Semiconductor website and get the LM317 data sheet, look at the circuit labeled "precision current limiter". It only has 2 parts, and works great.

If you want to pass 20 milliamps through the limiter the resistor calculates out to be 62.5 ohms.

The schemaitic is on page 19 of this: http://www.national.com/ds/LM/LM317.pdf

Good luck.

Russ

[livehho]

The LM317 is an excellent choice, I've used them many times.

If you get on the National Semiconductor website and get the LM317 data sheet, look at the circuit labeled "precision current limiter". It only has 2 parts, and works great.

If you want to pass 20 milliamps through the limiter the resistor calculates out to be 62.5 ohms.

The schemaitic is on page 19 of this: http://www.national.com/ds/LM/LM317.pdf

Good luck.

Russ

Thanks..

does this circuit has input or output overvoltage protection?

[ridelong]

The output is short circuit protected.

The input max is 40 volts, If your cars electrical system gets anywhere near 40 volts, the LM317 will be the least of your problems.

Russ