heart shaped pendant circuit

Electronic Heart Shaped Pendant

heart shaped pendant Remember, a sweetheart is waiting in the wings to receive an unusual gift from you not only on Saint Valentine’s Day! Here is an inexpensive circuit of a Heart Shaped Pendant built around the tiny microcontroller PIC 12F675. The pendant is nothing but a small LED artifact, changes its (limited) visual output pattern in play with the built-in tilt sensor. Only one CR2032 lithium battery is required to energize the lovely e-heart.

heart shaped pendant circuit

Working of the electronics is very simple like the wiring. An ultra simple code is used by the microcontroller for running the heart, based on PWM technique. Here, activity of the tilt switch changes the LED output pattern. The microcontroller code (ready-to-use hex code) can be downloaded from here. The source code is not included with this article due to commercial reasons. The test points (TP 1-2-3) in this pendant is reserved for future. Stay tuned to get some updates regarding new versions of this little project, ofcourse with the full source code at that time.

Major Components List

  • PIC 12F675 microcontroller – 1
  • 10uF/ 16V Electrolytic Capacitor – 1
  • 100nF Ceramic Capacitor – 1
  • 1K Resistor – 3
  • 10K Resistor – 1
  • 3mm/ 5mm Red/ Yellow LEDs – 3
  • CR2032 Lithium Battery – 1
  • CR2032 Lithium Battery Holder – 1

Every now and then I look for some enhancement on my design ideas. As usual, my first 9Vprototype (with on board voltage regulator) was built around traditional leaded-components on a small FR4 common circuit board. For the second prototype, an ordinary common circuit board -cutted into heart shape- was used. Finally, I am in a plan to build the pendant on a dedicated minuscule circuit board using SMD components, like 0805 package resistors, capacitors, and LEDs. Fortunately, PIC 12F675 is also available as an SMD (8-lead SOIC) chip.



  • PIC 12F series microcontrollers typically run at 5 Volts, and lower voltages at reduced speed
  • Try to put the 100nF decoupling capacitor as close to the microcontroller on the circuit board as possible

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