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Showing posts with label current. Show all posts
Showing posts with label current. Show all posts

Sunday, September 21, 2014

Current Controlled Boost LED Driver and Black Soldermasks

The MAX16834 is a neat little chip (its not the only one, there are plenty of others out there) that allows high efficiency designs for LED string driving. It provides a platform for a Buck or Boost converter design, as well as brightness adjustment via analog/PWM input pins, as well as a fault output (in case of open/short circuits for example) and also diverse other functionalities that can be quite useful. [Link]


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Friday, April 12, 2013

Current Monitor And Alarm

These circuits are intended for remote monitoring of the current consumption on the domestic mains line.

Fig 1 Current Monitor And Alarm-Circuit Daigram
The circuit in Fig. I lights the signal lamp upon detecting a mains current consumption of more than 5 mA, and handles currents of several amperes with appropriate diodes fitted in the D, and D2 positions. Transistor Ti is switched on when the drop  across D,-D2 exceeds a certain level. Diodes from  the well-known I N400x series can be used for currents of up to I A, while lN540x types are rated for up to 3 A. Fuse F, should, of course, be dimensioned to suit the particular application.

A number of possible transistor types have been stated for use in the Ti position. Should you consider using a type not listed, be sure that it can cope with surges up to 700 V. As long as Ti does not con- duct, the gate of the triac is at mains potential via  C,, protective resistor R2 and diode Da, which  keeps C, charged. When Ti conducts, alternating current can flow through the capacitor, and the triac is triggered, so that Lai lights.
Fig 2 Current Monitor And Alarm-Circuit Diagram
The circuit in Fig. 2 is a current triggered alarm. Rectifier bridge D4-D7 can only provide the coil voltage for Re, when the current through Di-D2 exceeds a certain level, because then series capacitor C, passes the alternating mains current. Capacitor C, may need to be dimensioned otherwise than shown to suit the sensitivity of the relay coil. This is readily effected by connecting capacitors in parallel until the coil voltage is high enough for the relay to operate reliably.

Finally, an important point: Many points in these circuits are at mains potential and therefore extremely dangerous to touch.

Source :http://www.ecircuitslab.com/2012/08/current-monitor-and-alarm-circuit.html
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