Showing posts with label ac. Show all posts
Showing posts with label ac. Show all posts

Friday, November 14, 2014

Simple 110 and 220V AC LED Voltage Indicator

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.
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Thursday, October 2, 2014

Simple AC Line Circuit Using LED Indicator

The circuit in the figure illustrates to power a LED from the 120 volt AC line using a capacitor to drop the voltage and a small resistor to limit the inrush current. This circuit can operate one or two LED. There are three concept to operate the LEDs. Operation of this circuit is when the capacitor must pass current in both direction, a small diode is connected in parallel with the LED to provide a path for the negative half cycle and also to limit the reverse voltage across the LED. A second LED with the polarity reversed may be substituted for the diode, or a tri-color LED could be used which would appear orange with alternating current.


The circuit is fairly efficient and draws only about a half watt from the line. The resistor value (1K / half watt) was chosen to limit the worst case inrush current to about 150 mA which will drop to less than 30 mA in a millisecond as the capacitor charges. This appears to be a safe values, I have switched the circuit on and off many times without damage to the LED. The 0.47 uF capacitor has a reactance of 5600 ohms at 60 cycles so the LED current is about 20 mA half wave, or 10 mA averages. A larger capacitor will increase the current and a smaller one will reduce it. The capacitor must be a non-polarized type with a voltage rating of 200 volts or more.
The lower circuit is an example of obtaining a low regulated voltage from the AC line. The zener diode serves as a regulator and also provides a path for the negative half cycle current when it conducts in the forward direction. In this example the output voltage is about 5 volts and will provide over 30 milliamps with about 300 millivolts of ripple. Use caution when operating any circuits connected directly to the AC line.
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Saturday, September 6, 2014

110 and 220V AC LED Voltage Indicator

110 and 220V AC LED Voltage Indicator Circuit Diagram. Useful for power lines control, Simple, transformer less schemary. This schema, 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 diagram, 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 schema and LEDs.

Circuit diagram:
110-220vac-voltage-
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 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 schema at the chosen voltage. If the case, please try values in the 8.2V - 15V range.
  • Warning! The schema is connected to 240Vac mains, then some parts in the schema board are subjected to lethal potential! Avoid touching the schema when plugged and enclose it in a plastic box.
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Sunday, August 24, 2014

12VDC to 220V AC 500W Inverter Circuit

Circuit Inverter 500 Watt 12VDC to 220VAC is made using a transistor.
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Wednesday, August 20, 2014

AC DC POWER SUPPLY MINIATURE ISOLATED


AC/DC POWER SUPPLY MINIATURE ISOLATED

AC/DC POWER SUPPLY MINIATURE ISOLATED CIRCUIT uses a novel approach to produce a fully isolated and regulated 5 volts @30ma from the 120vac power line. It uses two tiny SCRs that alternately discharge two capacitors through a miniature high frequency transformer. The voltage spikes produced through the transformer are rectified, filtered and regulated. A very common 8 ohm audio impedance matching transformer can be used for the transformer.
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