Voltage limiter / Clamper

 Doepfers DIY page

http://www.doepfer.de/DIY/a100_diy.htm

 

it's two low forward voltage diodes and a protection resistor.

You clamp the signal line to the rails using diodes.

Use two 5V zeners. One to +V and the other to -V.

This is a circuit that limits an incoming voltage to the range U1-UD2 ... U2+UD1. The voltage U1 has to be less than U2. UD1 and UD2 are the forward voltages of the diodes D1 and D2. To keep these voltages as small as possible Schottky diodes (e.g. BAT42) ore germanium diodes are recommended because their forward voltages are in the 0.2...0.3V range. R works as a serial protection resistor. A typical value for R is 1k.

A typical application is the limitation of an analog voltage to 0...+5V (e.g. for the inputs of Pocket Electronic or USB64). In this case U1 is connected to GND and  U2 to +5V.

Another application is sound distortion by voltage clipping. If U1 and U2 are variable voltages (e.g. outputs of operational amplifiers of one of the circuits in this document) the clipping levels can be voltage controlled too.

 

A 7805 will do a great job of limiting voltage and adding a current relator as well doesn't require too many extra components. .... +5V

 

or

LD1117V33 voltage regulator, a low drop positive regulator with a 3.3V fixed output voltage.