TV Pattern Generator
This single-IC TV pattern generator can help find problems with TVs. With the help of this circuit, you can fix the alignment of the TV's timing circuits. The pattern generator makes the…
Know the mission before touching a wire.
Understand what you are making, prepare the right tools, and make the workbench safe.
Project details
TV Pattern Generator is a electronics project. This single-IC TV pattern generator can help find problems with TVs. With the help of this circuit, you can fix the alignment of the TV's timing circuits. The pattern generator makes the…
- Source pages
- 65-66
- Named parts
- 2
- 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.
- This project may involve hazardous voltage. Work only with qualified supervision and proper isolation.
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
CD40106
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 CD40106; 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
PART LEARNING VIEWVR1, VR2, VR3, VR4, VR5 - preset potentiometers identified in the circuit
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 VR1, VR2, VR3, VR4, VR5 - preset potentiometers identified in the circuit; 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.
TV Pattern Generator: 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 noteThis single-IC TV pattern generator can help find problems with TVs. With the help of this circuit, you can fix the alignment of the TV's timing circuits. The pattern generator makes the TV screen show vertical stripes (bars) that help you line up the vertical scanning synchronization circuit of the receiver. To test the TV, you have to connect the video and audio outputs of the circuit to the TV's video and audio inputs one at a time. If the TV's video section is working, the circuit shows white lines going up and down the TV screen, and if the audio section is working, you can hear sound coming from the TV's speakers. You can also change the width of the lines going up and down.
The hex Schmitt inverter IC CD40106 is used in the circuit (IC1). Pulses that are horizontally synchronized (Hsync) for the PAL video signal are made by NOT gate N1. With the presets VR1 and VR2, you can control how long the oscillator is on and how long it is off. For PAL, you need to set VR2 so that it is "off" for about 4.7 s and set VR1 so that it is "on" for about 60 s. When you connect the video output of the circuit to the video input of the TV, if you see vertical lines on the TV screen, the video part of the TV is working. Potmeter VR3 lets you change where the lines start. Potmeter VR4 lets you change where the lines end. Potmeter VR5 lets you change the line width and the number of lines. If you don't have an oscilloscope, set VR1 and VR2 to 150k and 22k, respectively, to get the required "on" and "off" times for the oscillator and see the vertical line pattern on the TV. The NOT gate N6 is the main part of the audio frequency oscillator. The frequency of its oscillation is set by resistor R6 and capacitor C5. Connect the sound from the circuit to the TV's sound input. If you can hear sound coming out of the TV's speakers, the audio part is working.
You built TV Pattern Generator.
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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