Introduction: Love Lamp - Motion and Darkness Detecting

Picture of Love Lamp - Motion and Darkness Detecting

Place this near your favorite cuddle spot (works well in the bathroom, bedside, or anywhere you can use some gentle illumination) for instant soft light. Imagine bringing a loved one (or intended loved one) to your home and not having to make a spectacle or be obvious turning down the lights to set the mood. Or maybe you just want to share a romantic glass of wine as a reward with your significant other, having cooked a delicious meal or even washed the dishes. Also if could be a fun project for a parent and child making a toy into a night light for their bedroom. Use your imagination and you will think of many objects that can be used to make something wonderful and an inventive addition to your home.

Step 1: A "Set the Mood" Lamp

Picture of A "Set the Mood" Lamp

To start find a small lamp (this one was designed for a tea candle) or anything you think would like nice as a romantic light, child's night light etc. Thrift stores are an excellent place to find low-cost items to use in your project.

Step 2: Parts Needed

Picture of Parts Needed

The components needed are few to build this lamp.

  • PIR - Passive Infrared red motion detector. Generally they require a voltage of between 5 and 20 volts. Power consumption is 50 65mA (suitable for battery power) and can be adjusted to turn on an LED (or buzzer etc.) from about 20 seconds to 5 minutes. And the range of detection can be adjusted as well up to around 23 feet (7 meters) and has two settings for triggering. One setting triggers when motion is detected and then turns off after the set period and then triggers again if motion is again detected. The repeatable setting will trigger when motion is detected and if during this period further motion is detected it restarts the countdown. The signal sent is 3 volts which is enough to light an LED or several if wired in parallel.
  • LED(s)
  • NPN3904 transistor
  • 100k ohm resistor
  • LDR - Light dependant resistor that prevent the LEDs from coming on when the room is bright enough a light is not needed.
  • Wiring - 22AWG is more than heavy enough. In fact very thin wire will suffice.
  • 9 volt battery

Step 3: Put It Together

Picture of Put It Together

As you can see putting the circuit together is very easy. The emitter of the transistor goes to ground. The signal wire coming from the PIR is sent into two directions (splits or forks) with one going to the resistor, then on to the base of the transistor, but between the resistor and the base lead of the transistor it branches off to one lead of the LDR with the other lead of the LDR going to ground. The other half (wire) of the split goes to the positive leg of the LED (the longer of the two leads) or in the case of the bayonet style LEDs it goes to the lead without the flattened or beveled corner (chamfered) and then to the collector of the transistor. The negative leads of the LEDs just go to ground. The power to the PIR is provided by the 9 volt battery and so far mine has been running for several weeks on the original battery which has been probably subjected to more usage than normal because I am just trying to see how long it will last. I've added a link to the Frizting file so if needed you can get an close look at the circuit and components.

Frizting file

Fritzing Circuit Design Software

PIR Datasheet

HC-SR501 Infrared PIR

NPN3904

LDR Model: GL5528 - Bright Resistance (10Lux) (KΩ): 10-20 / Dark Resistance (MΩ): 1

Step 4: Extra Soft Light

Picture of Extra Soft Light

I cut a ping pong (table tennis) ball in half and hot glued it over the two LEDs on the protoboard and dropped the third LED down into the glass base of the lamp.

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Bio: Electronics have always been fascinating to me. Things that get my attention are clocks, lamps, motion activated devices, light activated devices, laser intruder alert systems ... More »
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