Regulator Circuit


Posted on Sep 1, 2012

The special characteristic of this regulator is that the output voltage can be adjusted down to 0 V. The regulation is pr


Regulator Circuit
Click here to download the full size of the above Circuit.

ovided by an integrated regulator Type LM317. As is normal in supplies that can be adjusted to 0 V, this IC is used in conjunction with a zener diode. This diode provides a reference voltage that is equal, but of opposite sign, to the reference voltage (U,) of the regulator, as shown in Fig. 74-1 (a). Potential divider R1/R2 enables the output voltage to be adjusted. In this circuit, the negative reference voltage is derived in a different manner: from the regulator with the aid of an op amp (Fig. 74-1 (b)). The op amp is connected as a differential amplifier that measures the voltage across Rl and inverts this voltage to Ur. An additional advantage of this method is that at low-output voltages, a change in the reference voltage has less effect on the output voltage than the circuit in Fig. 74-1 (a). The prototype, constructed as shown in Fig. 74-1 (c), gave very satisfactory results. The op amp need not meet any special requirements: a 741 works fine, although an LF356 gives a slightly better performance. The negative supply for the op amp can be obtained with the aid of a center-tapped mains transformer.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    HANGMAN schematic
    13.8Vdc 2A Regulated Power Supply Circuit
    Solid State Switch for magnet DC Generator
    50hz accurate oscillator circuit
    FET based audio preamplifier
    With a CD4011 dual-produced sound and light control delay lamp circuit
    Only one-way operation of the automatic control circuit of the motor
    Car or room timer alarm circuit diagram



    Top