- on Power Supplies
- Published in issue 7/2003 on page 0
78xx Voltage Regulators
The voltage regulators from the 78xx-series are found in many analogue power supplies. It seems, then, somewhat superfluous to say much more about them. But on the other hand, it can be very useful to highlight the important points, just because they are so ubiquitous.The 78xx is almost always used ‘bare’, because additional components are almost unnecessary. In fact, only one additional component is required, and that is capacitor C2. Based on the manufacturer’s recommendation, this capacitor should be 220 nF in order to prevent oscillatory behaviour. In practice, you will almost always see that a 100 nF capacitor used here. This is a value that does not cause problems.