This amplifier, from Philips Databook is suitable for automotive applications. The input resistance is 60k ohms and the frequency range is 20 to 20 kHz.
This circuit appears elsewhere on this site. Although the 8038 is not an easily obtainable...
The Texas Instruments TPS80 LDO (Low Dropout) series (www.ti.com) can provide fixed or adjustable output...
Found in Radio Electronics, this simple indicator circuit uses general-purpose transistors common today....