- on Miscellaneous Electronics
- Published in issue 7/2003 on page 0
Keypads are needed for a variety of applications and DIY projects. Particularly for selecting the measurement range of an instrument or setting the output voltage of a laboratory power supply, as well as for many other uses, potential-free relay outputs are desirable. In addition, break-before-make switching should be used to avoid short circuits. This cannot be guaranteed by simple relay circuits, since the pull-in speed of most relays is greater than the dropout speed!