Electronic Heart
If you have this electrical heart that glows on and off, you are sure to win the affection of that one person you have your eye on. In this particular circuit, a NE555 timer is set up to…
Know the mission before touching a wire.
Understand what you are making, prepare the right tools, and make the workbench safe.
Project details
Electronic Heart is a electronics project. If you have this electrical heart that glows on and off, you are sure to win the affection of that one person you have your eye on. In this particular circuit, a NE555 timer is set up to…
- Source pages
- 155-157
- Named parts
- 3
- Build goal
- Working, tested prototype
Tools you need
- Digital multimeter
- Wire stripper and side cutters
- Soldering iron with a fine tip
- Current-limited bench supply
Use eye protection, good lighting, and a clean insulated surface throughout the build.
Safety precautions
- Disconnect every power source before changing a connection.
- Check component polarity, pinout, and supply voltage twice.
- Use a current limit for the first power-up.
- Keep liquids, loose metal, and uninsulated wires away from the bench.
Gather, identify, and understand every part.
Use the standardized inventory, then open What's this? to learn each part's role, advantages, limitations, handling, and specifications.
What's this?Image, role, pros, cons, handling & specifications
SEMICONDUCTOR LEARNING VIEWNE555
A semiconductor stage performs switching, amplification, regulation, rectification, or logic.
What it does hereIt controls current or signal flow at a defined point in the circuit.
Buy / compare this part ↗Advantages
- Fast and efficient
- Compact
- Can control larger loads from smaller signals
Limitations
- Pin order varies
- Sensitive to overvoltage and reverse polarity
- May need cooling or bias components
Handling
- Verify the datasheet pinout
- Avoid static and soldering heat
- Check notch, stripe, or flat-face orientation
Specifications to verify
- Use the exact model, value, package, and rating listed for NE555; similar-looking parts are not always interchangeable.
- Confirm pinout, maximum voltage/current, dissipation, gain or forward voltage, and package.
What's this?Image, role, pros, cons, handling & specifications
SEMICONDUCTOR LEARNING VIEWBC548
A semiconductor stage performs switching, amplification, regulation, rectification, or logic.
What it does hereIt controls current or signal flow at a defined point in the circuit.
Buy / compare this part ↗Advantages
- Fast and efficient
- Compact
- Can control larger loads from smaller signals
Limitations
- Pin order varies
- Sensitive to overvoltage and reverse polarity
- May need cooling or bias components
Handling
- Verify the datasheet pinout
- Avoid static and soldering heat
- Check notch, stripe, or flat-face orientation
Specifications to verify
- Use the exact model, value, package, and rating listed for BC548; similar-looking parts are not always interchangeable.
- Confirm pinout, maximum voltage/current, dissipation, gain or forward voltage, and package.
What's this?Image, role, pros, cons, handling & specifications
MAXIMUM
A named project component whose exact role is defined by the source circuit and build guide.
What it does hereIt performs a documented electrical, control, interface, or construction function in this project.
Buy / compare this part ↗Advantages
- Selected for this project
- Can be checked independently
- Supports modular troubleshooting
Limitations
- Substitutes may differ
- Generic names can hide variants
- Pinouts and ratings vary
Handling
- Compare the received part with the source
- Keep it labelled
- Do not force connectors or adjusters
Specifications to verify
- Use the exact model, value, package, and rating listed for MAXIMUM; similar-looking parts are not always interchangeable.
- Confirm dimensions, ratings, connection method, polarity, and environmental limits.
Connect one verified path at a time.
Explore the named components and standardized signal flow, then use Source Check to verify exact physical pins, values, and topology before applying power.
Trace this circuit.
Electronic Heart: interactive parts, standardized terminals, responsive anchored wires, student explanations, and the original circuit reference in one shared system.
Trace before wiring
Follow power, ground, inputs, processing, and outputs in that order. Never guess a pin from package shape alone.
Connect with power off
Make short, labelled connections and share a common ground only where the schematic requires it.
Inspect every joint
Check continuity, polarity, adjacent shorts, and loose connections before the first power-up.
Open all source diagrams and build views 1 visuals
Confirm the hardware-only control path.
This project does not include firmware in the source. The circuit itself provides the required behaviour.
How to connect
- Match every controller label to the circuit view and source pin map.
- Join grounds before signal wires when separate low-voltage supplies are used.
- Keep motors, relays, pumps, and other loads on a suitable driver and external supply.
Common mistakes
Reversed VCC/GND, board-label versus GPIO-number confusion, missing common ground, and charge-only USB cables.
Troubleshoot
Disconnect loads, continuity-test one path at a time, then test with a current limit.
Software preparation
No IDE, board package, library, or firmware upload is required for this project.
If you add a programmable controller as an extension, document its pin map separately.
How to upload code
The original design is implemented entirely in hardware, so proceed after verifying the circuit and supply.
Assemble, deploy, test, and troubleshoot.
Use the complete source notes in build order, then pass the final checks before calling the project finished.
Build in functional stages
- Power and regulation
- Controller or processing stage
- Inputs and sensors
- Outputs and loads
- Enclosure and strain relief
Power up safely
- Inspect unpowered continuity first
- Apply the lowest safe current limit
- Measure supply rails before signals
- Add one load at a time
- Record expected and actual results
Work from simple to complex
- Confirm power, ground, polarity, and orientation
- Compare each pin with the source
- Test inputs separately from outputs
- Replace only one variable at a time
- Power off before every correction
Follow the documented instructions.
These notes come from this project's source and remain in their original order.
Project overview
Project build noteIf you have this electrical heart that glows on and off, you are sure to win the affection of that one person you have your eye on. In this particular circuit, a NE555 timer is set up to function as an astable multivibrator. The values of its resistors R1 and R2 as well as its capacitor C2 decide the frequency of its oscillations. In this case, the frequency is somewhere about 0.2 Hz. Each phase is slightly longer than 4 seconds in total duration. The capacitor C2 charges and discharges at a rate that is exponentially increasing as time passes. As a consequence of this, a sawtooth waveform looks more like a ramp. No matter what the voltage is across the capacitor, it cannot be used directly because doing so will only result in the capacitor being discharged or drained of its charge. A buffer is created by the transistor BC548 when it is set to operate in the common- emitter mode. This prevents the capacitor C2 from becoming loaded, which keeps the frequency of operation of the NE555 unaffected. Its emitter is connected to the four red LEDs that are wired in parallel with a resistor that is 100 ohms. A sawtooth waveform is generated here using the output from IC1's pin 6, which is used as the source. As a consequence, the LEDs will gradually and smoothly decrease to full brightness or return to their previous state. You can achieve the maximum voltage across the LED by making adjustments to the emitter resistance. If the value of the resistance is too low, the light output of the LEDs may have the appearance of a
sawtooth that has been clipped. In the event that it is excessively huge, the LEDs will switch off for a portion of the allotted time. The LEDs provide the impression of seamlessly following the voltage when the resistance is kept at 100 ohms. Build the circuit on a PCB that may be used for a variety of purposes, and then insert it within a styrofoam heart. Install the switch S1 on the left side of the heart. When you press it, the heart will begin to glow alternately on and off. When the lights go off, the results will be easier to see.
You built Electronic Heart.
You followed the full workflow from understanding the mission to testing the finished project. That is a real engineering achievement - well done.
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