Beating Heart LED Valentine Ornament




About: Part software developer, part maker.

In this Instructable I'll show you how I've built an LED ornament for Valentines day that I gave as a gift to my wife.

The circuit is inspired by another Instructable:

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Step 1: Prepare the Circuit

The circuit is very simple and it is based on the classic astible multivibrator that uses two transistors with two capacitors to alternatively flash two sets of LEDs. The circuit is most commonly done with just a single LED per transistor but you can add more without issues. The only difference is that the more LEDs you add the faster those blinks will be but that can also be addressed with bigger capacitors.

The full schematic is available on the link below:

Step 2: Layout the Components

I used a small perforated circuit board as the base for the project where I placed the LEDs in a heart pattern. The rest of the components are placed in the bottom to achieve a better look.

Step 3: Solder the Top Side

I first soldered all of the components in place from the top. This way I can prevent them from falling out when I turn the board to solder the back side and make all of the connections.

This worked well for most of the components but not for the LEDs as their pins are not exposed on the top side. To solve this, I've used a painters tape to keep the LEDs in place and I only soldered one leg of each. I then removed the tape and by pressing on each LED individually, I re heated the solder to make every LED flush with the board for a cleaner look.

Step 4: Solder the Circuit Connections

This was really tricky as I did not had a clear plan how to layout all of the connections and I just went with the flow and connected as they came. The interesting trick is that you can use some heat shrink to add over the exposed leads of the components to prevent any shorts.

When the mess was too great I continued making the connections using some insulated wire.

Step 5: Add the Battery Holder

I used 2 AA batteries to power the circuit but you can also use a LiPo or a 9V battery.

Step 6: Insulate and Assemble With Hot Glue

When I finished and tested the circuit to make sure everything works, I used my hot glue gun to flood the back side of the board and prevent any of the connections from moving. This way I know for sure that there won't be any shorts later on with using the ornament.

Also I used hot glue to mount the board to the battery holder so I can place the entire thing up right.

Step 7: Enjoy!

This was a really fun project and I truly recommend it for any electronics beginners that want to practice their soldering skills.

I hope that you liked it, so please follow me here on Instructables and subscribe to my YouTube channel for more projects in the future.

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10 Discussions


6 months ago

sorry but this is a MULTIVIBRATOR in A STABLE circuit, i think you need to change the name.
has nothing to do with a beating heart.

2 replies

Reply 6 months ago

I would suggest to rename this instructable to "blinking heart"


Reply 6 months ago

Yes, "MULTI-VIBRATOR" makes you think of other things. Blinky are known to a lot of people.


Question 6 months ago

I'm still rather new to circuit design.
It would be nice if you could show a schematic where it's laid out. I Don't know how to change the simpel diagram into the finished circuit.

2 answers

Answer 6 months ago

As you can see from the video above and the image attached, the layout turned quite messy on the back side, thus nothing to really see or understand. What I did is to just follow the schematic and connect one connection at a time.


Reply 6 months ago

Yes you are correct, I've used the wrong symbol but the number was correct. Anyway it is fixed now. Thanks!


Reply 6 months ago

I agree, it appears the incorrect transistor is depicted in the schematic.


Tip 6 months ago

Nice transition from multi-vibrator to valentine day theme.
A suggestion for next level (next year) - the leds could brighten and fade slower. Google "lm358 breathing leds" - lm358 is a very popular and cheap op amp IC - the rest of the components you probably already have. The idea of the circuit is similar - the op amp use the voltage on the capacitor as a feedback to drive the transistor gate. Charging and discharging (time also configured by the resistor value - RC time constant) causes the feedback delays leading to the hysteresis loop.