Beating Heart





Introduction: Beating Heart

About: Im a freelance electronics designer who loves to do photography and spends the day working for his college Solar Car Team apart from studying the B.Tech course in Electrical Engineering.

I made this good looking beating heart (.. Accidently invented near the valentines day. ;)).The device has 20 LED`S that blink at a hardware specified rate. Unlike the conventional approach of using micro-controllers i though using a simple 555 Timer would be great ..adding to it would simplify the design and make it less cuber-some for those who either have no prior knowledge or dont want to waste time gathering the same.
Here`s the thing you might get after going thru the rest of the instructable.

Step 1: Getting the Supplies

Things that are required:
1 x NE555 Timer 
2 x 10k Resistances
1 x 100uF Electrolytic Capacitor (25V)
1 x 10uF Electrolytic Capacitor (25V)
1 x 9V Battery / 3 x CR2032 Li-ion
1 x Through hole board
1 x 9V Battery connector
1 x  IC Base (8 pin)
1 x  Push Switch ( to avoid ur heart beats in front of everyone:D)
20 x  "identical" Red LED ( Identical is the catch in here.. as if they are sourced differently u might end up having uneven brightness..which will be disappointing) 
Wires as required..( it goes to like " Salt to taste")\
And lastly  "Spare Time"

Other Things that might be available at hobbyists are:
soldering Iron, Solder, Flux, Tweezers, wire cutters, Helping Hands ( Clamp tool)and hot glue gun.

Step 2: The Concept

Now that u have stuff..lets find out what actually is this-
NE555 is the most generic of all timers . Its supply range is 5V To 15V ( We are comfortable with 9V..).Its output current from datasheet is about 200mA which is enough to drive those 20 LED`s of mine..
Using an externally coupled circuit it can be used to decide the time a particular pin goes high or low( Thats called Timimg).

The rate of charging and discharging are determined by the RC Circuit.
To calculate your own custom timing which is subject to availability of components-
The timer runs in the Astable mode in our project ( to know more on this -

Now the circuit-
The LED`s are connected in parallel (so that one apple doesnt spoil the basket )  which makes connections easier.
I would suggest you to please pre-prototype the circuit on a breadboard and then make it towards the next steps( it adds to the motivation part)

Step 3: Building It-1

After you have pre-prototyped it need to do the following things..
1. In order to make the heart look a heart( specially for people with bad sketching as mine) please draw a heart on the non etched side of the PCB using a permanent marker and then proceed in laying the LED`s.. 
2. Since LED`S are round they are ought to follow the line as they can be placed with the two legs either vertically or horizontally.
3. Solder the legs and mark the positive ones.
4. Then clip the legs.( Thats the exciting part)
5. When you are done..solder the IC Base.

Step 4: Building It-2

Now that you have soldered it will..Its time for the nasty thing..
 and all -ve together.
You might have to make some common grounds somewhere and other modifications.
At the end of the exercise do test the +ve and -ve terminals with a continuity tester and say "crap" if the beep sounds.C

You will end up with something like this.

After all`s well..put hot glue gun to further reinforce the wiring..( That`s optional)

Then solder the components as in the circuit given earlier.
BEWARE- Do not connect the +ve of the battery supply to the LED.. Becoz thats what we have 555 for!

Step 5: Final Looks

Beating Heart from Indian Tinker on Vimeo. have done you have ur beating heart.
The completed Pics are-

You can keep this in your pocket ( if u wear a  shirt) and switch it the right time..
Also if you need to add more Leds you can use FETs and other things.

Hope you get your heart beating..

Thanks for being through this..

Please give your comments and suggestions.
Thats my First Instructable!
Hope i was able-to-instruct well..



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    14 Discussions

    Nice Ible....

    It jst doesnt seem to work.. Tink ill try doing pcb then see its working

    I'm beginner in electronics. I tried your ckt directly soldered it bt not leds. It didnt work. So bought new set n tried it on breadboard twice. It stil doesnt work. Tried with 2 555 time ICs. Pls help

    1 reply

    This may be a stupid question (it may be obvious to some) but how does the switch go into the circuit? I'm using a tactile switch and I hooked it up the way I thought it went but it didn't work. Any help would be great. Thank you.

    1 reply

    The switch is a not a tactile switch,Its a simple power switch i.e SPDT. When On(Pressed) the power is connected and when Off(Pressed Again) the power is disconnected. Tactile is SPST. So, when u press it , it will connect the circuit to the battery but when u release it, It will disconnect it. Try, Pressing(Holding) it longer. Else you can replace it with a SPDT switch.


    I'm a beginner in electronics. I tried your instructable and after 3 times I finally got it to work properly. I breadboard the circuit before I soldered it together. I should have done that first before I soldered it the first and second time. I read the schematic wrong the first and second time I tried it too. If you're a beginner like me breadboard it first like he suggest to save yourself a headache.

    1 reply

    Yeah! Bread boarding is the first acid test to the circuit.You can make some quick alterations as it happens very often while working with OPAM`s where you need to change some components to get the desired response. It saves a hell lot of time later on! Hope you enjoyed building it :D

    one question, how many watts is the resistance? I noticed in the video that the LEDs light up very fast, I just put a 200uF capacitor without changing anything else?

    2 replies

    Thanks for trying my instructable..
    All the resistors are 1/4 Watt since the current is not enough to blow any of them..I guess u have used a 200uF capacitor in place of the 100uF one..If that`s the case then the reason why your LED`s are beating slowly is as follows:
    In the Astable state of operation of a 555 timer the capacitor (100uF) is used for timing and decides the On Time and the Off Time. It appears in both the equations. So doubling the value will double the time constant and hence they beat slowly..I would suggest that you shud replace it with a 100uF one only..If you have another 200uF spare the connect them in series..To get a net capacitance of 100uF..
    The other capacitor is to not let CV terminal pick any stray voltages!

    Happy Tinkering!

    Thanks, I did and really got the show, will be allowed to create a post explaining how it does and of course keeping your credits, I made a change to create a gift for Valentine's Day. Sorry for the english, I am Brazilian.

    I guess a 555 timer Ic is the most awesome IC ever invented. I will make this

    This is cool. If you want to get a better heartbeat, make this circuit instead. It is supposed to be like a bomb but if you substitute the LEDs for the speaker, it will look much cooler.