Showing posts with label voltage. Show all posts
Showing posts with label voltage. Show all posts

Urg Negative Output from Positive Input Voltage

Friday, September 26, 2014 | Labels: , , , , , , | 0 comments |
There are some applications, such as double-ended sensors and audio amplifiers that require a negative voltage for operation. With limited space on today’s system boards, creating a dedicated negative supply rail would add to the cost and space of the PCB. Hence, it makes sense to generate the required negative voltage from existing positive supply rails in the system.


One such solution using a traditional synchronous step-down regulator is provided by Texas Instruments in an application note entitled “Creating an Inverting Power Supply Using a Synchronous Step-Down Regulator”1. It shows you how to generate a negative voltage from a positive input voltage to the synchronous buck regulator. [Link]
Continue reading...

Simple 110 and 220V AC LED Voltage Indicator

Wednesday, May 29, 2013 | Labels: , , , , , , , | 0 comments |
This circuit, designed on request, has proven to be useful to indicate when the voltage in a power supply line is changing from 120V to 240Vac. It can be used in different circumstances and circuits, mainly when an increase in ac or dc supply voltage needs to be detected. D3 illuminates when the line voltage is approaching 120V and will remain in the on state also at 240V supply. On the other hand, D6 will illuminate only when the line voltage is about 240V and will stay on because the latching action of Q1, Q2 and related components. C1, D1 and D2 provide a low dc voltage in the 4.5V - 6V range in order to allow proper operation of latch circuit and LEDs.

Circuit diagram

 

Parts:

  • R1_____________470R 1/2W Resistor
  • R2_____________220K 1/4W Resistor
  • R3,R7__________470R 1/4W Resistors
  • R4_______________1K 1/4W Resistor
  • R5_______________2K2 1/4W Resistor
  • R6_____________330R 1/4W Resistor
  • C1_____________330nF 630V Polyester Capacitor
  • C2______________10µF 25V Electrolytic Capacitor
  • D1,D2________1N4007 1000V 1A Diode
  • D3,D6___________LEDs (Color and shape at will)
  • D4_________BZX79C10 10V 500mW Zener Diode (See Notes)
  • D5___________1N4148 75V 150mA Diode
  • Q1____________BC547 45V 100mA NPN Transistor
  • Q2____________BC557 45V 100mA PNP Transistor

Notes:

  • D4 value could require some adjustment in order to allow precise switching of the circuit at the chosen voltage. If the case, please try values in the 8.2V - 15V range.
  • Warning! The circuit is connected to 240Vac mains, then some parts in the circuit board are subjected to lethal potential! Avoid touching the circuit when plugged and enclose it in a plastic box.
Continue reading...

110 and 220V AC LED Voltage Indicator

Saturday, April 13, 2013 | Labels: , , , , , , | 0 comments |
Useful for power traces control, Simple, transformerless circuitry
This circuit, designed on request, has confirmed to be useful to indicate when the voltage in an influence supply line is changing from 120V to 240Vac. It can be utilized in numerous situations and circuits, mainly when an increase in ac or dc supply voltage must be detected. D3 illuminates when the road voltage is drawing near 120V and will stay in the on state also at 240V provide. On the opposite hand, D6 will illuminate best when the road voltage is about 240V and can stay on for the explanation that latching motion of Q1, Q2 and related elements. C1, D1 and D2 present a low dc voltage within the four.5V - 6V vary in order to permit right kind operation of latch circuit and LEDs.

Circuit diagram:

110 and 220V AC LED Voltage Indicator Circuit Diagram
Parts:
R1__________470R 1/2W Resistor
R2__________220K 1/4W Resistor
R3,R7_______470R 1/4W Resistors
R4__________1K 1/4W Resistor
R5__________2K2 1/4W Resistor
R6_________330R 1/4W Resistor
C1_________330nF 630V Polyester Capacitor
C2_________10µF 25V Electrolytic Capacitor
D1,D2______N4007 1000V 1A Diode
D3,D6______LEDs (Color and shape at will)
D4_________BZX79C10 10V 500mW Zener Diode (See Notes)
D5_________1N4148 75V 150mA Diode
Q1_________BC547 four5V 100mA NPN Transistor
Q2_________BC557 four5V 100mA PNP Transistor

Notes:
  • D4 price could require some adjustment to be ready to permit precise switching of the circuit at the chosen voltage. If the case, please try values in the eight.2V - 15V range.
  • Warning! The circuit is connected to 240Vac primarys, then some phases within the circuit board are subjected to lethal potential! Avoid touching the circuit when plugged and enclose it in a plastic field.


http://www.ecircuitslab.com/2011/07/110-and-220v-ac-led-voltage-indicator.html
Continue reading...