This Make: project describes a portable analog function generator powered by one 9V battery, with sine, square, and triangle outputs. Its published specifications are approximately 20 Hz to 11 kHz and an adjustable output from 0 to about 3 V peak-to-peak. The guide below explains how the circuit works and what the published construction instructions cover; these specifications are not independent bench-test results.
What the 9V function generator can do
Gretchen Giles’s Make: project, published December 14, 2013, is intended as a small signal source for basic electronics troubleshooting and experimentation. The circuit offers three waveform outputs and a level control. Make: reports an overall frequency range of about 20 Hz to 11 kHz and an output level adjustable from zero to about 3 V peak-to-peak. These are approximate values reported in the article.
The article gives more specific approximate ranges for its two frequency settings: about 16–590 Hz on the lower range and about 400 Hz–10 kHz on the higher range. The overlap lets the controls cover frequencies near the transition; the project’s headline summary rounds the overall range to about 20 Hz–11 kHz. Do not treat these figures as calibrated limits.
The output is deliberately modest. This is a battery-powered, low-voltage source, not a substitute for a laboratory generator when precise amplitude, frequency accuracy, low distortion, or substantial load current is required. The Make: article does not specify a sine-wave distortion measurement or a battery-runtime estimate.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
#1 Best Overall
- Never Let a Dead Battery Ruin Your Drive. The LISEN 4 in 1 Retractable Car Charger delivers reliable power for your entire journey. Compatible with standard 12V cigarette lighter sockets, it keeps phones, tablets, and devices charged during daily commutes, road trips, and long drives — the perfect practical gift for dads, truck drivers, and anyone who lives on the road.
- Daily Driver Essential: Always Ready When You Need It. Featuring two retractable cables ( USB C & Old iPhone Charging Cable ) that extend up to 31.5 inches and dual USB ports, this charger solves cable clutter while charging up to 4 devices simultaneously. Ideal for busy fathers, commuters, and families who want a tidy car and never worry about low battery again.
- Deliver full-speed PD fast charging for iPhone 18 Pro Max & iPhone 18 Pro Max & iPhone 18 Pro right inside your car. The built-in 45W PD USB-C port hits the peak charging speed for these latest iPhone models, juicing up your phone to 50% power in just 15 minutes while you drive.(Note: Maximum 45W PD output is available under 24V vehicle power supply. When used with standard 12V car sockets, the peak output is limited to 36W.)
- Standard 12V Power Solution: Designed as a dedicated USB power supply for charging devices. Note: Does NOT support CarPlay, Bluetooth, or data transfer. Compatible with most phones, tablets, and small electronics. This retractable charger is a core car organization tool, keeping your vehicle tidy. Not compatible with Micro-USB devices.
- Clutter-Free Tech Organization: Featuring dual USB ports and retractable cables, the LISEN 4 in 1 charger provides a clean car storage solution. Perfect for truck enthusiasts or as a thoughtful gift for drivers, it supports fast USB-C charging for devices like the iPhone 18Pro & iPhone 18 ProMax. Keep your vehicle organized while ensuring efficient power delivery for all your tech on the road.
How the circuit makes its waveforms
Virtual supply from one battery
The circuit uses two 4.7 kΩ resistors to create a midpoint reference from the 9V battery. Two 220 µF electrolytic capacitors serve as charge reservoirs. Make: describes the resulting arrangement as approximately +4.5V and −4.5V around virtual ground. This is a split reference made from a single battery, not two separate 4.5V batteries.
That limited supply explains the circuit’s constrained signal swing. It is designed around the available battery voltage rather than to provide a large output amplitude.
Rank #2
- High Quality Material: The coaster is made of environmentally friendly silicone, safe, non-toxic and odorless. Soft with toughness, easily embedded in the cup holder. Very durable, wear-resistant, long service life. High temperature resistance, can withstand 100 ℃ high temperature water cups.
- Wide Compatibility: The coaster has a diameter of 3.15 inches and a height of 1.18 inches, which is widely used in most vehicles, such as SUV, sedan, MPV, etc., as long as the size fits your car cup holder.
- Protection Function: Our car cup holder coaster has a carry handle design and a stand-up ring edge on its edge to effectively prevent food crumbs, drinks and water from leaking out and preventing the car cup holder from getting dirty.Meanwhile,Thickened design effectively prevents the cup holder from being scratched by the cup when driving on bumpy roads and eliminates the annoying thumping sound, making your journey more enjoyable.
- Easy to Use and Clean: With embedded installation, you just need to put it flat on the car cupholder. It is also very quick to remove, there is a small bump on the coaster, pinch it and you can easily remove the coaster. It is very easy to clean, rinse with water or wipe with a wet towel (be careful not to clean with sharp tools).
- 100% Satisfaction: Our products have quality assurance, if you have questions or are not satisfied after receiving the product, don't worry, please contact us as soon as possible, we provide after-sales service.
Triangle and square waves
Two sections of a TL074 quad operational amplifier form the oscillator core. One section integrates a changing voltage to produce the triangle wave; another acts as a comparator and switches state to produce the square wave. A pair of diodes helps balance the feedback level in both directions, supporting a more symmetrical triangle.
The range switch changes the integrator timing by placing a larger capacitor in parallel with the integrator capacitor. This changes the frequency band available from the tuning control.
Rank #3
- ✅【Designed for Magsafe】 - The most fashionable iphone car mount in 2026 Magsafe is designed for iPhone 18 Pro Max/17/16/15/14/13/12 Pro Max Mini and official Magsafe cases and other magnetic phone cases and can be fixed directly to these phones without the need to affix metal plates. All Android Phones Will Work: Metal rings are provided; they fit cases and other phones without magsafe. Based on Unique Grandmaster Design (Protected by US Design Patent No. US D1,112,194 S)
- ✅【STRONG MAGNETIC MagSafe Car Mount】 - This powerful magnetic phone holder can create a powerful attraction that firmly supports your device while allowing you to drive without distraction. it easily and securely holds your phone through bumps, sharp turns or even sudden stops, no worrying of dropping your phone.
- ✅【SUPER STICK FORCE】 - VHB Dash Mounted Holders adhesive provides strong stick force between the dashboard and the car phone holder, which can firmly stick to any plane in the car, fix your device, adapt to a variety of road conditions such as sudden braking, speed bump, and rugged mountain road.
- ✅【SAFE DRIVING VIEW】 - Mini-size, not taking up space, it is placed in the dashboard without blocking the view at all, and does not need to look down at the device to ensure your safe driving. Cell Phone Car Mount is suitable for most cars, pickups, SUV, taxi; It is the best assistant for Uber and Lyft drivers
- ✅【360° FREE ROTATION】 - With an adjustable swivel ball joint, you can rotate your smartphone or device at your own will, providing the best viewing angle. Quickly pick and place with one hand, free your hands and make calls and GPS navigation more convenient
Sine approximation and output selection
An LM13700 transconductance amplifier shapes the triangle wave into an approximate sine wave by overdriving it so the triangle’s peaks curve inward. The project describes three sine adjustments: distortion amount, top-to-bottom symmetry, and amplitude. This is a shaping method, not evidence that the output meets a particular distortion specification.
A third TL074 section scales the square output, while the fourth provides the selected, level-adjusted output with low output impedance. The article reports about 3 V peak-to-peak maximum output, but does not establish drive performance for a particular load; avoid assuming it can directly drive low-impedance equipment.
Rank #4
- Buyer's Guide: The seat guard for car seat between seat & console measures 15.75*2.7*1.53", suitable for gaps of 1.43-1.53" in width, please double-check carefully the distance between your seat and the center console before placing an order
- Storage and Filling in One: Differ from traditional single-function gap fillers, gap filler for car incorporates storage function, offers you the convenience of storing phones and various other items, so that you can access them at any time while driving
- Avoid Items Slipping: With the bumps and vibrations of the car, phones, keys may fall into the seat crevices, which is difficult to pick up, and distracts the driver's attention. Car gap seat filler fills gaps seamlessly to create an effective barrier
- Easy to Install: Car side seat gap filler is easy to install, simply insert it into the gap between the seat and the center console, gap seat filler for car can fit tightly without affecting the normal adjustment of the seat and the use of the seat belt
- Premium Material: Crafted from premium EVA material, our car seat side gap filler boasts a combination of wear-resistant, softness&durability. Maintenance is effortless, simply rinse and wipe to quickly clean the dust and debris in corners and crevices
Parts and construction approach
The Make: bill of materials specifies TL074CN and LM13700N ICs, two 1N914 diodes, resistors, 100 kΩ controls and trimmers, ceramic and electrolytic capacitors, SPDT and SPST switches, banana jacks, hookup wire, a board, an enclosure, a 9V battery, and a 9V snap connector. The article says capacitors should be rated for 16V or higher. Check the original project’s component list and circuit drawing for exact quantities, values, and connections: Make a 9V Battery Powered Function Generator.
The project can be assembled on experimenter board or on an etched PCB. Ray Wilson’s 2014 construction companion adds guidance on PCB artwork orientation, component placement and designators, wire jumpers, and wiring the panel controls: Constructing the Battery Signal Generator. It recommends connecting a conductive faceplate to circuit ground with a wire to help reduce noise.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsBest Value
- 🔰 UPGRADED SIDE STORAGE DESIGN - Our console cover is thinner than the old one, universal for all seasons. There is an 8.66*5.12 inch storage pocket design on each left and right side, expanding the storage space, convenient and practical. Meet the storage needs of the main passenger seat, you can store your cell phone, keys, tissues, ID and some other small daily items.
- 🔰 PREMIUM MICROFIBER LEATHER MATERIAL - This car center console cover is made of quality microfiber leather material, soft and skin-friendly touch. Exquisite and fashionable diamond shaped stitching, every detail is in place. Inside the car center console cover is made of thickened memory foam, even after squeezing, it can slowly recover to its original shape.
- 🔰 RELIEVE DRIVING FATIGUE - The arm rest cover for car adopts ergonomic design, giving just the right amount of arm support, effectively dispersing elbow pressure and relieving driving fatigue. Protect your car's center console from getting dirty or scratched. Especially suitable for long time driving or long distance traveling, bringing you a new experience of relaxation and comfort!
- 🔰 NON-DESTRUCTIVE INSTALLATION - This car console cover is designed with an elastic band for a firm fit and not easy to shake. And the back side is full of protruding dots, which can effectively avoid the armrest cover from slipping and shifting. All you need to do is to open the center console cover, put the elastic band directly into the cover and then close it.
- 🔰 BUYER'S GUIDE - You will receive a car armrest storage box with the size of 12.13*7.80 inch, please measure the size of your car's armrest storage box before you buy. We have prepared five simple and beautiful colors for you, you can choose according to your own preferences. Suitable for most of the vehicles on the market, such as car, truck, SUV, RV, van, etc.
If you choose chemical PCB etching, the construction companion advises gloves, goggles, good ventilation, and proper chemical disposal. Follow the current safety instructions for the specific chemicals and products you use; those general precautions do not replace them.
What to expect from battery use and adjustment
Make: reports current draw of about 11 mA with the LED fitted and about 9 mA without it. These are article-reported figures, not independent measurements. Current draw alone is not enough to calculate dependable battery life: runtime depends on the battery, its condition, circuit behavior, and use, and the project does not publish a runtime figure.
The sine-shaping controls require adjustment for distortion, symmetry, and amplitude. If you need repeatable output specifications, verify the assembled unit with suitable test equipment; the project article does not publish measured distortion, frequency accuracy, or calibration results.
Keep other function-generator designs distinct
A separate XR2206 DIY kit manual specifies a regulated 12V supply and advises adding a buffer stage for low-impedance loads. Those are requirements and recommendations for that kit, not for the Make: 9V circuit: XR2206 DIY Kit manual.
Recommended Free Tools
The Renesas ICL8038 datasheet search result lists a 10–30V single supply or ±5V dual supply. That supply statement alone is not enough to treat the IC as a drop-in substitute in this one-battery design; changing the generator IC may require a different power arrangement. See the Renesas ICL8038 datasheet.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
