Makerspaces.com has some terrific electrical circuit templates, especially for the holidays. They are ready to be printed and all you need is LED diodes, Coin Cell batteries, and copper tape to easily create electrified cards.

Check out Makerspaces.com Valentine’s templates available for free download.

As an alternative that doesn’t require any additional supplies, search circuits on a site such as pexels.com that has images available for reuse. Choose an image you like and download. Open up Google Drawings and Insert your downloaded circuit image. Then crop your image in the shape of a heart. (Not sure how to crop images into shapes, here’s a quick tutorial.). You can add text over your heart shape and print or download as an image to share.