AC to DC & DC to DC

This nonisolated, unregulated, minimum component converter fills the void between low-power zener regulation and the higher power use of a 60-Hz input transformer. It is intended for use where)"er a nonisolated supply can be used safely. The circuit operates~by conducting only during the low-voltage portion of the rectified sine wave. ..

Views: 13 | Votes: 83 | Comments: 0 | Rating: 2 | Rank: 5 | Added: Feb 16, 2013 |

This circuit uses two comparator pairs from an LM339N quad comparator; one pair drives the yellow positive (+)and negative (-)indicators, the other jointly drives the red warn LED3. The circuit draws its power from the unregulated portion of the power supply. The four comparators get their switching inputs from two parallel resistor-divider strings. Both~strings have their ends tied between the power supply"s positive and negative output terminals. ..

Views: 3 | Votes: 107 | Comments: 0 | Rating: 8 | Rank: 5 | Added: Feb 14, 2013 |

The circuit behaves like a zener diode over a large range of voltages. The current passing through the voltage divider R1-R2 is substantially larger than the transistor base current and is in the region of 8 mA. The stabilizing voltage is adjustable over the range 5-45 V by changing the value of R2. The total current drawn by the circuit is variable over the range 15 mA to 50 mA..

Views: 1320 | Votes: 19 | Comments: 0 | Rating: 4 | Rank: 5 | Added: Feb 12, 2013 |

This circuit utilizes the quasi-complementary output stage of the popular LM380 audio power IC. The device is internally biased so that with no input the output is held midway between the supply rails Rl, which should be initially set to mid-travel, is used to nullify any inbalance in the output. Regulation of Vout depends upon the circuit feeding the LM380, but positive and negative outputs will track accurately irrespective of input regulation and unbalanced loads..

Views: 842 | Votes: 100 | Comments: 0 | Rating: 4 | Rank: 5 | Added: Feb 7, 2013 |

This power supply uses an LM317J adjustable regulator and an MJ2955 pass transistor. Ql and U2 as..

Views: 19 | Votes: 80 | Comments: 0 | Rating: 1 | Rank: 5 | Added: Feb 2, 2013 |

It is usually desirable to have the remote transmitter of a 4 to 20 mA current loop system powered directly from the transmission line. In some cases, this is not possible because of the high-power requirements set by the remote sensor/transmitter system. In these cases, an alternative to the separate power supply is still possible. If the remote transmitter can be operated in a pulsed mode where it is active only long enough to perform its function, then a charge.....

Views: 1 | Votes: 12 | Comments: 0 | Rating: 2 | Rank: 5 | Added: Jan 30, 2013 |

In this circuit, a full-wave bridge is switched to a full-wave center tap to reduce regulator dissi..

Views: 7 | Votes: 72 | Comments: 0 | Rating: 5 | Rank: 5 | Added: Jan 30, 2013 |

This supply can serve as a battery eliminator for various devices (such as tape recorders, small..

Views: 8 | Votes: 44 | Comments: 0 | Rating: 8 | Rank: 5 | Added: Jan 29, 2013 |

These circuits provide overvoltage protection in case of voltage regulator failure or application of an external voltage. Intended to be used with a supply offering some form of short circuit protection, either foldback, current limiting, or a simple fuse. The most likely application is a 5 V logic supply, since TTL is easily damaged by excess voltage. The values chosen in A are for a 5 V supply, although any supply up to about 25 V can be protected by simply choosing the.....

Views: 5281 | Votes: 30 | Comments: 0 | Rating: 4 | Rank: 5 | Added: Jan 27, 2013 |

Positive output step-up and step-down de-de converters have a common limitation in that neither can handle input voltages that are both greater than or less than the output. For example, when converting a 12-V sealed lead/acid battery to a regulated +12 V output, the battery voltage might vary from a high of 15 V down to 10 V. By using a MAX641 to drive separate P-and N-cbannel MOSFETs, both ends of the inductor are switched to allow noninverting buck/boost operation. ..

Views: 15 | Votes: 41 | Comments: 0 | Rating: 5 | Rank: 5 | Added: Jan 25, 2013 |

When equality of two equations shown in satisfied, full-wave output of circuit is symmetrical. ..

Views: 1947 | Votes: 78 | Comments: 0 | Rating: 0 | Rank: 5 | Added: Jan 23, 2013 |

This circuit derives 5 Vdc from 2-AA cells—even at their end-life voltages of 1.05 V, and is approximately 80% ef..

Views: 1 | Votes: 106 | Comments: 0 | Rating: 4 | Rank: 5 | Added: Jan 22, 2013 |

The circuit provides accurate full wave rectification. The output impedance is low for both input polarities, and the errors are small at all signal levels. Note that the output will not sink heavy current, except a small amount through the 10K resistors. Therefore, the load applied should be referenced to ground or a negative voltage. Reversal of all diode polarities will reverse the polarity of the output..

Views: 3226 | Votes: 69 | Comments: 0 | Rating: 3 | Rank: 5 | Added: Jan 18, 2013 |

A simple 120 V: 24 V, center-tapped control transformer and four additional components can do the job. This circuit outputs a clean 200 V pk-pk square wave at 60 Hz and can supply up to 20 W. The circuit is self-starting and free-running. If Q1 is faster and has a higher gain than Q2, it will tum on first when you apply the input power and will hold Q2 off. Load current and transformer magnetizing current then flows in the upper half of the primary winding, and.....

Views: 11 | Votes: 6 | Comments: 0 | Rating: 7 | Rank: 5 | Added: Jan 18, 2013 |

This circuit responds to the difference between Vj and V2. Rq on sets gain. Resistors XR2 and (1 -X) R2 pro..

Views: 1 | Votes: 102 | Comments: 0 | Rating: 7 | Rank: 5 | Added: Jan 16, 2013 |

By coupling two back-to-back diodes in series with an ac power circuit, a voltage of about 1.4 Vpp can be obtained. This..

Views: 4 | Votes: 7 | Comments: 0 | Rating: 0 | Rank: 5 | Added: Jan 6, 2013 |

Each stage provides ° to 180° phase shift. By ganging the two stages, 0° to 360° phase shift is achieved..

Views: 5539 | Votes: 4 | Comments: 0 | Rating: 6 | Rank: 5 | Added: Jan 2, 2013 |

The circuit powers the load via the regulator"s input instead of its output. Because the regulator"s output sees constant dummy load R1, it tries to consume a constant amount of current, no matter what the voltage across the actual load really is. Hence, the regulator"s input serves as a constant-current source for the actual load. ..

Views: 4 | Votes: 53 | Comments: 0 | Rating: 2 | Rank: 5 | Added: Jan 2, 2013 |

The value of the design lies in the use of IC1, an LM317HVK adjustable s.eries-pass voltage regulator, for broad-range performance remainder supplies voltage-setting and current-limiting functions. The input to ICI-comes from the output of BR1, which is filtered by CI and C2 to about +60 Vdc, and the input for current-sense comparator IC2 comes from BR2,..

Views: 34 | Votes: 79 | Comments: 0 | Rating: 9 | Rank: 5 | Added: Jan 1, 2013 |

A TMOS power FET, Ql, and an LM393 comparator provide a high-efficiency rectifier circuit. When V,. exceeds V,, Ul"s output becomes high and Ql conducts. Conversely, when VB exceeds V,., the comparator output becomes low and Ql does not conduct. The forward drop is determined by Ql"s on resistance and current I. ..

Views: 9 | Votes: 30 | Comments: 0 | Rating: 1 | Rank: 5 | Added: Dec 29, 2012 |