Introduction: Analog Heartbeat Gauge

About: I teach electronic Toy Design at the Parsons School Of Design.

Experience the rhythm of life with the Analog Heartbeat Gauge, a hands-on bio-feedback device that transforms your heartbeat into the motion of a classic analog needle. From the slow, rhythmic dance of controlled breathing to the quick tempo of aerobic exercise, the Analog Heartbeat Gauge voltmeter offers a window into the fascinating world of human physiology. This project brings a touch of old-world charm to modern science, providing a unique and visually engaging way to observe your pulse in real time.

Designed for simplicity and ease of use, the Analog Heartbeat Gauge requires no programming or soldering. It's perfect for quick assembly and ideal for tabletop demonstrations, combining the aesthetics of vintage science with user-friendly functionality. Whether it's a weekend project or a classroom activity, it offers an accessible and educational experience.


2 x AA Battery Holder with Knife Switch

  • Description & Purpose: This unique battery holder powers the device and features a retro knife switch.
  • Why Used in Education: Illustrates electrical circuit concepts and engages students in learning about open/closed circuits in a hands-on manner.
  • Source: Adafruit

Mini Solderless Breadboard

  • Description & Purpose: Ideal for DIY projects, matching jumpers, and prototyping circuits, electronic, and electrical experiments without soldering. Works great with Arduino and similar platforms.
  • Why Used in Education: Facilitates hands-on learning in electronics by allowing students to experiment and prototype without the need for soldering. Enhances understanding of circuit design and functionality.
  • Source: Amazon

Small Alligator Clip to Male Jumper Wire

  • Description & Purpose: Essential connectors for linking components without soldering.
  • Why Used in Education: Simplifies the process of making connections, good for demonstrating circuit assembly.
  • Source: Adafruit

Large 3V Analog Panel Meter

  • Description & Purpose: The visual display for pulse rhythm.
  • Why Used in Education: Visually engaging way to demonstrate the measurement of physiological data.
  • Source: Adafruit

PulseSensor Kit

  • Description & Purpose: Precision sensor for detecting heartbeats.
  • Why Used in Education: Introduces students to biometric sensing and data collection.
  • Source:

2 x AA Batteries

Step 1: 3 Project Files to 3D Print

Device Enclosure, On/Off Lever, and PulseSensor Holder

  • The steps below walk through each 3D part, that was designed in Fusion 360. It's using the Fusion's share feature, so you can open, and edit, copies of these files in Fusion 360.
  • Why Used in Education: Engages students in modern manufacturing techniques and design thinking.

Step 2: Unibody Enclosure

The Analog Heartbeat Gauge voltmeter's enclosure blends vintage aesthetics and practical design. Inspired by old sci-fi movies, it features a retro-style analog voltmeter and a 'Dr. Frankenstein'-like Knife Switch AA battery holder. The design focuses on ease of use and 3D printing:

  • Vintage Science Look: Emulates the classic look of old science equipment.
  • User-Friendly Design: Ensures easy access to internal components.
  • 3D Printing Compatibility: A unibody design optimized for simple and efficient 3D printing, requiring minimal supports.

This step is about creating an enclosure that's both nostalgic and functional, ideal for educational purposes.


Step 3: Install the Panel Voltmeter

Remove Back Screws: Begin by unscrewing the back of the panel voltmeter.

Align the Voltmeter: Position it correctly in the enclosure.

Mark Polarity: Identify and mark the positive (+) and negative (-) terminals on the back of the voltmeter with a marker for easy reference.

Secure in Place: Reattach the voltmeter to the enclosure, ensuring it's aligned and the screws are snug but not overly tight.

Step 4: Threading Battery Cables and Installing the Battery

Install Batteries: Insert two AA batteries into the knife switch holder. Note the color coding of the cables: black for negative (-) and red for positive (+).

Carefully thread the color-coded cables from the AA battery holder through the designated openings in the enclosure.

Push into place until the knife switch and 3D printed handle has just enough clearances to open and close.

Step 5: Install the Knife Switch Batteries

Attach Frankenstein-Inspired Handle: Fit the handle onto the knife switch for a cool look and easier operation.

Position the Knife Switch: Install the switch to face the same direction as the voltmeter, pulling the cables through and positioning the battery holder correctly.

Test Switch Operation: Ensure the knife switch opens and closes smoothly without any issues.

Check Battery Health: Use the voltmeter to test the battery pack's strength. The meter should quickly jump to 3 volts when switched on. If it's slow or doesn't reach 3 volts, replace with fresh batteries.

This step is key for both the aesthetic and functional setup of your Analog Heartbeat Gauge, ensuring the power system is reliable.


Step 6: Insulate Surface of PulseSensor

Apply the vinyl dots included in the PulseSensor kit to its surface. These clear dots insulate the sensor, preventing direct skin contact while maintaining its functionality.

Step 7: Sensor Holder Base and Shade

Snap the PulseSensor into its holder. It's designed for a secure snap fit with the sensor.

Thread the PulseSensor wires through the small hole in the enclosure for neat cable management.

Attach the top shade over the sensor to reduce light pollution, enhancing its effectiveness. Depending on your printing settings, you the shade should snap in place like a lego piece.

This setup ensures the PulseSensor is securely installed and functions effectively, free from light interference.


Step 8: Threading PulseSensor Cables Into Unibody

Thread the PulseSensor cables through the designated opening in the unibody enclosure for neat and secure cable management. This ensures organized wiring.

Step 9: Setting Up the Mini Solderless Breadboard

Utilize Solderless Breadboard: Use the compact breadboard for simple connections, replacing larger ones. Only 3 columns are needed for this setup.

Create Ground Rail: Connect all black cables to form a ground rail, including the black gator clip.

Create Power Rail: Connect all red cables from the battery to form a power rail.

Connect PulseSensor's Purple cable to it's own row. This row also connect the blue gator clip. This connects the purple cable to the positive side of the voltmeter.

Step 10: Test Your Circuit and Hide the Wires, Make Things Look Pretty

Put the solderless breadboard and assoicated cables into the "trunk" of our new device.

Step 11: Flip the Switch and It's Alive!

Activate the Device: Flip the switch to power on your Heartbeat Gauge. It's now alive and functioning, Mwahahaha!

Initially, the gauge will shoot straight to 3 Volts, similar to the battery test. After 3-4 seconds, the pointer will settle around 1.5 Volts.

The PulseSensor works by translating reflected light into voltage, making it readable by both microcontrollers and analog voltmeters. Its baseline reading is 1.5 Volts when no finger is present. As a sensitive light sensor, you can observe needle movement by altering the light exposure on the sensor, like moving your hand back and forth over it.

Step 12: Operation Basics, Identifying the Pulse

Steady State at 1.5 Volts: Wait for the needle to stabilize around 1.5 Volts, indicating it's ready to read a pulse.

Placing a Finger: Put a fingertip over the sensor. The voltmeter will initially react strongly for 1-2 seconds as it recalibrates in real time, then settle back to around 1.5 V.

Observing the Pulse: Once stabilized, the needle will show the pulse rate in real-time.

Ensuring Reliable Readings: Maintain even pressure on the sensor for accuracy. Inform others, especially new users, that the real pulse signal stabilizes post-recalibration.

Step 13: Easily Calculate BPM

To calculate beats per minute (BPM) using a 15-second recording, you can use the following formula:

  1. Count the number of heartbeats (pulses) you detect in 15 seconds.
  2. Multiply this number by 4 to estimate the BPM.

Formula: BPM=Number of Beats in 15 seconds×4

BPM=Number of Beats in 15 seconds×4

This multiplication is necessary because there are 60 seconds in a minute, and you are measuring for only 15 seconds. So, multiplying by 4 scales your count to a full minute.

Step 14: Fruitful Future Directions for Biology and Life Science Students

Project: Measuring Resting, Active, and Controlled Heart Rates

Objective: Use the BPM formula to measure and compare resting, active, and controlled heart rates through deep breathing exercises.

Project Overview: Students will record their heart rates at rest, after light exercise, and following deep breathing exercises to understand the impact of physical and relaxation activities on the cardiovascular system.


  1. Understanding BPM Calculation: Review the BPM formula (BPM = Number of Beats in 15 seconds × 4) for converting short-term heart rate measurements to a per-minute rate.
  2. Resting Heart Rate Measurement: Students measure their heartbeat for 15 seconds while at rest and calculate their BPM. Record these rates for later comparison.
  3. Active Heart Rate Measurement: After light physical activity like jogging in place, students immediately measure their heart rate for 15 seconds and calculate their active BPM.
  4. Deep Breathing for Heart Rate Control: Students then engage in a few minutes of deep, controlled breathing. Following this, they measure their heart rate for 15 seconds to calculate the controlled BPM.
  5. Data Analysis: Compare the resting, active, and controlled heart rates among students. Discuss how physical activity and deep breathing affect heart rate differently.
  6. Class Discussion: Explore why heart rate increases with exercise and decreases with deep breathing. Discuss the implications for stress management and cardiovascular health.

Learning Outcomes: Understand the heart's response to rest, exercise, and relaxation; learn manual heart rate measurement and calculation; develop insights into managing heart rate and stress.

This project offers a comprehensive look at cardiovascular health, involving students in practical data collection and analysis to understand the effects of different activities on heart rate.

Step 15: Fruitful Future Directions for Design Students

Objective: Utilize Fusion 360 to redesign the Heartbeat Voltmeter, focusing on innovative form, intuitive user interface, and futuristic styling.

Project Overview: Students will take the existing components of the Heartbeat Voltmeter and reimagine it, considering form factor, material, switch placement, and overall style.

Enclosure Redesign:

  • Challenge: Create a new embodiment for the Heartbeat Voltmeter using different materials, colors, or original design concepts.
  • Considerations: How do material and color choices impact the user experience?

Reconsider the User-Interface:

  • Task: Rethink the placement and design of the Knife Switch (and On/Off Lever) and/or the Voltmeter Gauge.
  • Goal: Enhance user experience changing the position of the Knife Switch and the Voltmeter Gauge.
  • Focus: Consider how the change in style alters the device's appeal to different end-users.


  • 3D Models/Sketches: Detailed sketches or 3D models of the redesigned Heartbeat Voltmeter.
  • Design Description: A summary discussing design choices, materials used, and the rationale behind the placement and styling of existing components.
  • Prototype (Optional): If resources permit, 3D print and create a physical prototype of the redesigned device.

Learning Outcomes:

  • Gain proficiency in 3D modeling and design customization.
  • Explore the interplay between design, materials, and user experience.
  • Innovate in blending modern aesthetics with functional technology design.

This project encourages design students to think outside the box, applying their skills to a real-world device while considering sustainability, ergonomics, and modern design trends.

Step 16: Fruitful Future Directions for Engineering Students

Project Ideas for Mechanical and Electrical Engineering Students

Exploring Alternative Display Mechanisms:

  • Objective: Investigate various low-power devices like meters, actuators, solenoids, electromagnets, toy motors, or lights that can be integrated into the project to represent the heartbeat in alternative ways besides the traditional needle gauge.
  • Activities: Design and implement alternative mechanisms to display the heartbeat, such as LED arrays, digital screens, or mechanical movements.

Solar-Powered PulseSensor:

  • Objective: Modify the project to be powered by a small, inexpensive solar cell, similar to those used in toys.
  • Challenge: Determine the feasibility and efficiency of powering the device solely with solar energy.
  • Spoiler Alert: Yes, it’s possible. The project explores green energy applications in low-voltage electronics.

USB or Lightning Cable Powered Circuit:

  • Objective: Redesign the circuit to be powered via a USB connection or a repurposed lightning cable, potentially from devices nearing end-of-life.
  • Innovation: Focus on sustainability by repurposing cables for power supply, exploring how everyday items can be reused in new technological applications.

Learning Outcomes:

  • Develop a deeper understanding of low-power electronics and their applications.
  • Explore renewable energy sources and their integration into small-scale devices.
  • Innovate in repurposing and recycling electronic components for new uses.

These projects provide mechanical and electrical engineering students with hands-on experience in designing and modifying circuits, encouraging innovation and sustainability in engineering practices.

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