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led night lamp schematic

LED Night Lamp Circuit

The design of the LED night lamp circuit (bedroom light) is similar to that of many commercially available products. However, the light circuit does not use any kind of bulky and noisy stepdown transformers, but a capacitive potential divider is inserted in a simple manner to provide a constant current for driving the light source. Here a high-efficiency, low current blue LED is used as the light source. The design is safe, simple and stable!

Night Lamp Circuit Schematic

led night lamp schematic

When input power (AC 220V) is available, capacitor C2 is charged through C1 and R2 and bridge rectifier assembly D1-D4. Zener diode D5 limits the voltage across C2 to a safe value of near 15V. This low voltage dc supply is then fed to the LED (D6) via current limiting resistor R3. When the input supply is removed, LED stays on unchanged for a short time and then diminishes gradually. No instant darkness when the supply is switched off!

Related Products: Lighting Solutions

After construction, enclose the circuit in a small plastic box. Drill a 5mm hole in the centre of the enclosure and fit the LED in a suitable LED holder in the 5mm hole. Finally fit a supply input socket and, optionally an on/off switch at the rear/side of the enclosure.

WARNING! Great care should be taken when working with this led night lamp circuit since it is connected directly to the fatal mains supply.

27 Comments

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  • Ignacio

    Hello!

    I am trying to power this circuit:
    http://electroschematics.com/5643/sensitive-clap-switch/

    with this exact same diagram. Instead I am using a 9.1v zener diode and 120vac (with the C1=.1uF, just like Jim told me) But I find out that the clapper switch only switches once and then it stays the same no matter what…

    At first I thought it could be the “excess” 0.28 volts given by the upper circuit. But then I thought…could it be because of the current? if so, how can I handle it?

    thanks!

  • Jim Keith

    Only a marginal difference in brightness –slightly dimmer

  • ignacio

    Good news, I just made this circuit and everything worked properly. There are no “time limits” in which it reaches maximum time it can be plugged right? can it be uses just as any othee electrical appliance?

    • Jim Keith

      It should have a 10,000hr life.

    • ignacio

      Mission accomplished. I’ve one more question. I have been using the LEDCALCULATOR.NET, and a 13v zener diode. According to the calculator, a 512Ohms resistor would be good, but my question here is: would it be safe?

      because there is a lot of difference between 2.7kOhms, and 512Ohms…

    • Jim Keith

      Yes, it is safe. Actually, there may be very little difference in brightness due to the way the circuit works. Use standard value 4.7K that is close enough.

    • ignacio

      I found a circuit that only uses:
      1 capacitor 1.5uF
      1 270 ohms resistor
      1 zener diode (5 volts)
      1 diode 1n4002
      1 1000uF capacitor

      *———-(1.5uF)–(1n4002)———–(+5vout)
      | |
      120vac | |
      (zener) (1000uF)
      | |
      | |
      *——–(270 ohms)———————————–(-5vout)

      my question here is, if I used a 1uF capacitor, would it make a big difference?

  • Jim Keith

    No problem with the 1M resistor –it is a safety bleeder to discharge the series capacitor when power is removed.

    On the 470Ω resistors, parallel (4) devices because these must limit the initial inrush when power is initially applied. The proper type of resistor for this application is carbon composition, but those are are no longer available. Ceramic composition are the preferred type but they are not commonly available. The commonly available carbon film are quite fragile in application –have low pulse energy rating.

  • ignacio

    I got all the resistors but “1/2 watt” will they still work?

  • Ignacio

    Hello, great circuit.

    I am really interested in building this circuit, but I’d like to know if parameters should stay the same if I have a 120v AC source?

    thanks

  • Muhammad Ashfaq Butt

    its better to use simple circuit: 3X 100K resistance in parallel, then attach in4007 in series with white LED +side and attach with 220AC. its tested.
    watch circuit at:
    http://youtu.be/aUaTXQPSxWU

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