Ball Speed Checker
This ball speed checker circuit uses the time it takes the ball to move from the bowling crease to the batting crease to figure out how fast the ball is going. Ball speed checker circuit…
Know the mission before touching a wire.
Understand what you are making, prepare the right tools, and make the workbench safe.
Project details
Ball Speed Checker is a electronics project. This ball speed checker circuit uses the time it takes the ball to move from the bowling crease to the batting crease to figure out how fast the ball is going. Ball speed checker circuit…
- Source pages
- 389-391
- Named parts
- 4
- 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
Buzzer
An output component turns an electrical control signal into light, sound, motion, switching, or displayed information.
What it does hereIt presents the circuit result or acts on the physical world.
Buy / compare this part ↗Advantages
- Makes system state visible
- Can be tested separately
- Supports clear troubleshooting
Limitations
- Loads may exceed controller current
- Polarity or driver direction can matter
- Inductive loads create voltage spikes
Handling
- Use the documented driver stage
- Check polarity and load current
- Add flyback protection for inductive loads
Specifications to verify
- Use the exact model, value, package, and rating listed for Buzzer; similar-looking parts are not always interchangeable.
- Confirm voltage, current, polarity, interface, driver requirements, and duty cycle.
What's this?Image, role, pros, cons, handling & specifications
MODULE LEARNING VIEWLDR
A sensor converts a physical condition into an electrical signal the circuit can measure.
What it does hereIt provides project input as an analogue, digital, resistive, frequency, or calibrated signal.
Buy / compare this part ↗Advantages
- Adds real-world awareness
- Can usually be tested independently
- Often supports calibration
Limitations
- Readings can drift
- Placement affects results
- Some sensors need warm-up or calibration
Handling
- Protect the sensing surface
- Observe supply voltage and polarity
- Keep signal leads away from noisy power wiring
Specifications to verify
- Use the exact model, value, package, and rating listed for LDR; similar-looking parts are not always interchangeable.
- Confirm supply range, output type, measurement range, accuracy, response time, and pin order.
What's this?Image, role, pros, cons, handling & specifications
Push button
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 Push button; similar-looking parts are not always interchangeable.
- Confirm dimensions, ratings, connection method, polarity, and environmental limits.
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.
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.
Ball Speed Checker: 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 2 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 noteThis ball speed checker circuit uses the time it takes the ball to move from the bowling crease to the batting crease to figure out how fast the ball is going. Ball speed checker circuit Figure 1 shows that the circuit is made up of two NE555 timer ICs (IC1 and IC2), a 74C926 (IC3), an LTS543 (display), and a few other parts. In bistable mode, the first NE555 timer (IC1) is wired. The output of IC1 is connected to pins 4 and 8 of IC2, which is wired as an astable multivibrator and makes a 1 kHz frequency. IC3 counts and shows what comes out of IC2. Around LDR1 and LDR2, there are two light barriers that send out signals when the ball blocks the laser beam as it moves from the bowling crease to the batting crease. Circuit operation When the ball goes through the bowling crease, it briefly blocks the IR beam from reaching LDR2. This sends a pulse to IC1's pin 2, which then
sets IC1. When IC1's output goes high, it gives +5V to IC2 and turns it on. IC2 then starts oscillating. IC3 keeps track of these pulses and shows them on 7-segment displays (DIS1 through DIS4). When the ball goes past the batting crease, it stops the laser beam from reaching LDR1. This sends a pulse to IC1's pin 6 and turns it back on. IC1's output goes low, which stops +5V from going to IC2 and turns it off. IC2 stops moving back and forth, and IC3 stops counting. On 7-segment displays, the time is shown. From 0 to 9999, which is 10 seconds, the counter counts up. About 18 meters separate the bowling crease from the batting crease. Now you can figure out the speed of the bowling ball by plugging in the distance and time it takes the ball to travel from the bowling
crease to the batting crease in the following formula
Project build noteTwo mirrors that reflect light can be stuck to wooden bases to make a sensor. Figure 2 shows how the mirrors should be set up on the sides of the bowling crease. Attach a laser flashlight to one of the mirrors. After hitting the mirror in front of it, the laser beam must make a small angle so that it bounces back and forth between the mirrors until it reaches the LDR at the bottom of the mirror. In this way, the laser beam makes a barrier of light. When the ball gets in the way of the beam, a pulse is made. Put another of these sensors on the side where the batter is.
Construction & testing
Project build notePut the circuit together on a PCB for general use and put it in a small cabinet. Connect the buzzer to the circuit and put this alarm watch somewhere convenient. You can power the circuit with a 6V adapter instead
of a 6V battery. Put the LEDs and the push button on the front panel and connect them to the board.
You built Ball Speed Checker.
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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