walid Posted August 5, 2012 Report Share Posted August 5, 2012 The circuit in the following figure (from: http://www.hobby-circuits.com/circuits/power-supply/dc-power-supply/891/variable-dc-power-supply) represents a variable power supplyTransistor Q1 is npn type This was corrected in the following figureI have thought carefully about this circuit, but I could not get to the mechanism of how it work!I think that when the transistor Q1 operates, it must turn off Q2.I try to simulate it using multisim10, but it didn't work, that is when I change the value of any of P1 or P2 the output is fixed at near the retectified voltage.Any help in clarifying the way this circuit work would be welcome, thanks Quote Link to comment Share on other sites More sharing options...
indulis Posted October 29, 2013 Report Share Posted October 29, 2013 Think about it this way... first remove the current limit stuff (Q3, R4, P1). Then what to do with Q1... the collector-base looks like a diode... that "kinda works". I don't see how making Q1 a n-p-n will work at all. Then add the current limit function back in. Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted November 15, 2013 Report Share Posted November 15, 2013 A center tapped transformer is perfect for producing a negative dc supply voltage. This one doesn't have one. Quote Link to comment Share on other sites More sharing options...
Hero999 Posted November 15, 2013 Report Share Posted November 15, 2013 A center tapped transformer is perfect for producing a negative dc supply voltage. This one doesn't have one.This circuit uses a bi-phase rectifier. Each diode acts as a single phase rectifier but the AC voltage applied to D2 is 180o out of phase, thus full wave rectification is achieved. Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted November 17, 2013 Report Share Posted November 17, 2013 Hello Walid, the circuit you found was I think novice. Q3 is an NPN. Indulis recommends removing the resistors and I agree. The load has to be high impedance. Most versatile regulators need to sink current sometimes. Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted November 18, 2013 Report Share Posted November 18, 2013 Try this circuit. It is good for analogue only. Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted November 20, 2013 Report Share Posted November 20, 2013 Here's a better circuit. Quote Link to comment Share on other sites More sharing options...
login
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.