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As an electrical engineer, a function generator is a tool you'll find yourself turning to regularly. It's essential for creating various electrical waveforms, crucial in your daily tasks of designing, testing, and troubleshooting circuits. The function generator you choose can greatly affect the success of your projects.
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Imagine this scenario: You are working on a critical project with tight deadlines. Your current function generator, that you've been using for years, struggles with accuracy and reliability. Testing drags on, each delay ticking closer to that looming deadline. The pressure mounts as you realize you're at risk of not finishing on time.
While the project doesn't fail outright, these delays put strain on your team and could even affect your reputation. Now, you're left wondering, "Could a better function generator have made the difference?"
What is a Function Generator?
A function generator is a tool that generates different electrical waveforms over a wide range of frequencies and is the most common type of signal generator. It's a fundamental piece of equipment for anyone involved in electronics or electrical engineering.
With it, you can simulate various conditions for circuits, making it invaluable for design, testing, troubleshooting, and education. The right function generator can make your work more efficient and reliable, helping to keep projects on track.
Types of Function Generators
Function generators are vital tools for electrical engineering, offering a variety of options tailored to different needs and applications.
The main types available in the market include analog, digital, arbitrary waveform generators (AWGs), and software-based function generators. Each type has unique strengths and limitations, making them suitable for various applications.
Choosing the Right Function Generator
Analog function generators: These are best suited for straightforward tasks where basic waveforms like sine, square, and triangular waves are sufficient. They're ideal for educational purposes and basic circuit troubleshooting.
Digital function generators: These offer more precision and a wider variety of waveforms, making them suitable for more complex projects that require detailed signal simulation.
Arbitrary waveform generators: (AWG) are the top choice for applications requiring the utmost flexibility and precision. They can generate any waveform, modeled after real-world signals, which is essential for research and development in cutting-edge technologies.
Software-based function generators: These provide a good balance between flexibility and cost. They are suitable for environments where customizability and upgradability are key, such as in educational settings or startups.
When selecting a function generator, consider the specific requirements of your application, including the complexity of the tests, the precision needed, and your budget. Here's a comparison table to help you understand the differences between each type of function generator:
TypeProsConsBest ForAnalog
- Simple to use
- Often more affordable ' Immediate waveform output
- Limited waveform variety
- Less precision and flexibility
Basic circuit testing and educationDigital
- Greater precision ' More waveform options
- Easy integration with digital systems
- Can be more expensive than analog
- Slightly more complex to use
Advanced circuit design and digital system testingArbitrary Waveform (AWG)
- Maximum flexibility in waveform generation
- High precision
- Ability to simulate real-world signals
- Higher cost
- May require more expertise to fully utilize
Complex and precise testing, research, and developmentSoftware-Based
- Highly customizable
- Can be updated or upgraded easily
- Lower hardware cost
- Dependent on computer system
- Potential compatibility issues
Flexible environments, education, and budget-conscious labs
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When choosing a function generator, it's important to understand the key specifications and performance parameters. These details not only determine the device's capability but also ensure it meets the specific needs of your projects.
Let's consider some of these critical parameters to understand their importance and impact on a function generator's performance.
Wave Frequency, Range, Resolution, and Precision
- Wave frequency: Refers to the number of cycles a waveform completes in one second, measured in Hertz (Hz). It dictates the speed of the signal generated by the function generator.
- Range: Indicates the spectrum of frequencies a function generator can produce, from the lowest to the highest frequency. This range is essential for ensuring the function generator can cover the necessary frequencies for various applications.
- Resolution: This is the smallest increment of frequency that the generator can handle. Higher resolution means you can make finer adjustments to the frequency, which is critical for applications requiring precise signal tuning.
- Precision: This relates to how accurately the function generator can produce the set frequency. It's a measure of the device's ability to generate signals that closely match the specified settings without significant error.
Real-World Applications and Impacts
An engineer might use a function generator to simulate different audio signals when designing a new audio amplifier. Here, the range of the function generator needs to cover the full spectrum of human hearing (roughly 20 Hz to 20 kHz) to test the amplifier properly. The resolution is important when the engineer wants to precisely pinpoint the frequency at which the amplifier might introduce distortion or lose efficiency.
Output Characteristics
Understanding the output characteristics of a function generator, such as amplitude, load impedance, and waveform distortion, is crucial for ensuring the accuracy and effectiveness of your experiments or projects. These characteristics define how the signal interacts with the device under test and can significantly affect the outcome of your work.
- Amplitude: Refers to the maximum height of the waveform, indicating the strength of the signal output. It's essential for matching the signal level required by the device under test.
- Load impedance: The resistance the function generator expects at its output. Matching the generator's output impedance with the load impedance of the device being tested is crucial for accurate signal transmission.
- Waveform distortion: Occurs when the shape of the waveform deviates from the ideal due to various factors, including the function generator's limitations. Minimizing distortion is critical for applications where signal integrity is paramount.
Users should look for function generators that offer high-quality output with the flexibility to adjust these characteristics according to their specific needs. The ability to fine-tune amplitude, properly match load impedance, and minimize waveform distortion ensures the reliability and accuracy of your testing and experimentation.
Comparing Output Characteristics of Different Function Generators
FeatureBasic AnalogAdvanced DigitalArbitrary Waveform Generator (AWG)Amplitude RangeLimitedWideWidestLoad ImpedanceFixedAdjustableAdjustable, with detailed settingsWaveform DistortionHigherModerateLowest
Advanced digital and AWG models typically offer better control and lower distortion levels, making them suitable for more demanding applications.
Frequency Stability and Phase Lock Capability
Frequency stability is a measure of how consistently a function generator maintains the set frequency over time. This stability is vital for applications requiring precise and consistent signal generation, such as in communications testing, where even minor frequency drifts can lead to significant errors in data interpretation.
Phase lock capability refers to a function generator's ability to synchronize its output phase with an external signal or another generator. This capability is crucial when working with multiple signals that must be coherently aligned, such as in phased array systems, complex modulation testing, or when simulating multi-channel scenarios.
Importance in Applications
In a radar system test, frequency stability ensures that the simulated signals remain consistent, allowing accurate measurement of the system's sensitivity and response over time.
With phase lock capability, engineers can synchronize multiple function generators to simulate complex environments or signals, such as coordinating the signals in a multi-antenna communication system to test beam-forming algorithms.
Choosing a function generator with robust frequency stability and phase lock capability is essential for ensuring the precision and reliability of your work, especially in advanced and high-precision applications.
Modulation and Sample Rate
Modulation is the process of varying a waveform to encode information. In function generators, modulation capability allows the user to simulate real-world signals more accurately by applying amplitude, frequency, phase modulation, or more complex modulation types.
This feature is crucial for testing communication systems, electronic components, and control systems where the signal's behavior under various modulation schemes is of interest.
Sample rate refers to the frequency at which the function generator samples the digital representation of the waveform. A higher sample rate means that the waveform is represented with more data points, leading to greater fidelity and accuracy in the generated signal.
This is especially important when creating complex or high-frequency waveforms, as it ensures the waveform's nuances are accurately reproduced.
Scenarios Requiring High Modulation Capability and Sample Rates
Communication systems testing: High modulation capabilities are essential for simulating the various modulation schemes used in wireless communication, such as QAM or PSK, to test receiver sensitivity and error rates.
High-fidelity audio equipment testing: High sample rates are crucial when testing audio components to ensure the generated signal accurately represents audio frequencies without aliasing or distortion.
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Bandwidth and Record Length
Bandwidth, in the context of a function generator, refers to the range of frequencies it can accurately generate. Higher bandwidth allows the generator to produce a wider range of frequencies, from very low to very high, allowing it to test devices across a broad spectrum of applications.
Record length is the total duration of the waveform that can be stored and generated by the function generator. A longer record length allows for the generation of more complex or longer-lasting waveforms, which is crucial when simulating signals that change over time or when a precise simulation of real-world signals is required.
Impact on Waveform Production
- Broadband RF component testing: High bandwidth is necessary to test components in broadband RF systems, ensuring they operate correctly across their entire frequency range.
- Long-duration signal simulation: Long record lengths are essential for simulating signals that vary over time, such as the output of a varying sensor in environmental testing or long communication signals in network testing.
Noise and Jitter
In electronic signal generation, noise and jitter are critical factors that can significantly affect signal integrity and the accuracy of test results.
- Noise: Refers to any unwanted variation or interference in the signal. It can be caused by a variety of sources, including electrical interference from other devices, thermal fluctuations, or inherent imperfections in the function generator itself. Noise can distort the signal, making it difficult to accurately measure the response of the device under test or to simulate real-world signals accurately.
- Jitter: A specific type of temporal noise that affects the timing of the signal. It refers to the variability in the time position of the signal's edges, leading to uncertainty in the signal's phase and frequency. Jitter is particularly problematic in digital communications and any application where the precise timing of signal transitions is critical.
Effects on Signal Integrity
- Noise can reduce the clarity and accuracy of the signal, leading to errors in measurement and potentially masking the effects you're trying to observe or simulate.
- Jitter can cause bit errors in digital communications, disrupt synchronization between signals, and degrade the performance of systems that rely on precise timing.
Specifications to Minimize Issues
Users should look for function generators with:
- Low phase noise: This indicates the generator produces a stable frequency with minimal short-term variations, crucial for applications requiring high-frequency stability.
- Low jitter specifications: A function generator with low jitter is essential for digital signal applications, ensuring that timing errors are minimized.
- High signal-to-noise ratio (SNR): A high SNR means that the signal is much stronger than the background noise, ensuring clearer, more accurate output.
Understanding User Interface and Ease of Use
A user-friendly interface in a function generator significantly reduces setup time and improves overall efficiency. Whether you're conducting complex experiments or routine tests, the ease with which you can navigate settings and adjust parameters directly impacts your productivity and the accuracy of your results.
1. Touchscreen interfaces: Offer intuitive navigation and easy access to a wide range of features and settings. Ideal for complex applications where multiple parameters need adjustment.
- Pros: Easy to use, visually appealing, allows quick adjustments.
- Cons: Can be prone to fingerprints and smudges, potentially less durable than physical controls.
2. Physical knobs and buttons: Provide tactile feedback and can be easier to use without looking, which some users prefer for quick adjustments.
- Pros: Durable, precise control, works well in environments where gloves might be worn.
- Cons: May require more time to navigate through menus for complex settings.
When choosing a function generator, consider the following based on user preference and application complexity:
- For applications requiring frequent and rapid adjustments, physical knobs and buttons might offer better control.
- For complex setups with multiple parameters, a touchscreen interface could simplify navigation and reduce setup time.
- Consider the environment in which the device will be used. In labs where users wear gloves or where equipment might be subject to spills, physical controls could offer advantages in durability and usability.
Selecting a function generator with an interface that matches the user's preference and the complexity of the application can greatly enhance the testing and development process, making it more efficient and less prone to errors.
Power Requirements and Connectivity Essentials
Understanding the power requirements and connectivity options of a function generator is crucial for ensuring it fits seamlessly into your work environment, whether that's in a laboratory, in the field, or as a portable solution.
Power Requirements
- Laboratory applications: Typically rely on standard AC power sources. Ensure the function generator matches your lab's power supply in terms of voltage and frequency.
- Field applications: May require function generators with battery options or those that can operate on a wider range of power sources.
- Portable applications: Look for devices with low power consumption, battery operation capabilities, and lightweight design for ease of transportation.
Connectivity Options
- USB: Universal and easy to use, ideal for direct connection to a PC for data logging or control with custom software.
- Ethernet: Suitable for integration into networks, allowing remote control over LAN, which is beneficial for automated test systems or environments where the generator is part of a larger setup.
- GPIB (General Purpose Interface Bus): Though older, GPIB is still widely used in laboratory environments for connecting and controlling multiple devices in a test setup.
Relevance for Integration
USB and ethernet connections are essential for modern test environments where integration with computer-controlled setups is common. They offer flexibility in controlling the function generator from software, enabling automated testing and data collection.
GPIB remains relevant for setups that rely on this traditional standard, especially in labs with existing GPIB-controlled equipment, ensuring compatibility and ease of integration.
The Importance of Channel Options
Channels in a function generator allow you to output multiple waveforms simultaneously, significantly expanding the device's capabilities. Each channel can operate independently, enabling the generation of complex signal scenarios, such as simulating multiple sensors or communication signals at once.
Available Options
- Single channel: Basic option, suitable for straightforward applications where only one waveform is needed at a time.
- Dual channel: Allows for two independent waveforms to be generated, useful for comparative testing or simulating two-part signals.
- Multiple channels (four or more): Ideal for advanced applications requiring the simulation of several signals or complex multi-channel communication systems.
Balancing Quality with Cost
Function generators vary widely in price, influenced by their capabilities, precision, brand, and additional features. Prices can range from a few hundred dollars for basic models to several thousand for high-end, feature-rich options.
Factors Affecting Cost
- Precision and range: Higher precision and wider frequency ranges typically increase the price.
- Number of channels: More channels add to the cost due to increased versatility.
- Connectivity and interface options: Advanced connectivity (Ethernet, USB, GPIB) and user-friendly interfaces (touchscreen) can raise the price.
Tips for Balancing Budget and Features
- Assess core needs: Focus on function generators that meet the essential requirements of your projects to avoid paying for unnecessary features.
- Consider future projects: Investing a bit more in a function generator with advanced capabilities can save money in the long run if it means avoiding the need to upgrade sooner.
- Look for deals on bundled software: Some function generators come with software packages that can add value.
- Explore used or refurbished equipment: Purchasing from reputable sources like the Keysight Used Equipment Store can significantly reduce costs while still providing quality and reliability. These options often come with limited warranties, offering a balance between cost savings and peace of mind.
"All of the equipment I sell is Premium Used. I don't like to call it just 'used', because it's so much more than used equipment." ' Keysight Account Manager
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Choosing a function generator from a reputable brand with excellent customer support is crucial. It ensures reliability, durability, and access to help when you need it, affecting the long-term value and usability of your investment.
Factors to Consider
- User reviews: Research what current users say about the product's performance and reliability. User experiences can offer insights beyond the specifications.
- Warranty terms: Look for brands that offer comprehensive warranties. The length and coverage of the warranty can signal the manufacturer's confidence in their product.
- After-sales support services: Ensure the brand provides accessible and helpful customer support. Availability of technical support, repair services, and software updates are key for long-term satisfaction.
- Community and resources: Brands that foster a community or offer extensive resources (tutorials, forums, FAQs) can enhance your user experience and provide valuable troubleshooting, and help.
Selecting a function generator from a brand that values quality and customer satisfaction not only secures your investment but also ensures a smoother, more supported user experience throughout the product's life.
"Customers come to us and buy used, because they get premium KS quality, with a lower price, and we ship within 2 weeks. New equipment right now takes up to 14 weeks to ship." ' Keysight Account Manager
Conclusion: Engineer Your Success with the Perfect Function Generator
Thinking back to that opening scenario about projects dragging on past deadlines because of unreliable equipment, it's clear why getting this decision right matters so much. Armed with the knowledge from this guide, you're ready to choose a function generator that won't let you down, ensuring your next project is on track for success, without the stress and strain of before.
Choosing the right function generator directly influences the efficiency and success of your projects. We've gone through everything you need to think about, from the nuts and bolts of wave frequency and modulation, to ease-of-use features, power demands, and how it'll fit with the rest of your gear. We've also looked at why the number of channels matters, how to weigh up cost against features, and the importance of picking a brand you can trust.
Engineer your success with a Keysight function generator that's as ambitious and forward-thinking as you are. The right choice will elevate your projects, streamline your workflow, and allow you to tackle challenges with confidence, precision, and efficiency.
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nour
what should I look for when buying function generator?
«
on: December 20, , 11:26:26 am »
Hi, I would like to own function generator for the hobby and I don't know anything about what should I look for in function generators when buying them
I see gen. begin from around 50-60$ on ebay up to s $
I need to know what should I look for when buying function generator?
thanks
EDITBy the way, for now I will not set a price limit, I just want to know what is the things that I should care about and the things that I should avoid
« Last Edit: December 20, , 12:14:46 pm by nour »
if what I have wrote doesn't make sense for you or you think there is something wrong, please correct me, I am still beginner and what I know probably less than what you know
The following users thanked this post: Doogs
tautech
Re: what should I look for when buying function generator?
«
Reply #1 on: December 20, , 11:54:01 am »
If you want a well featured unit this might interest you:
http://www.siglentamerica.com/pdxx.aspx?id=&T=2&tid=16
I might add if you buy the 40 MHz unit you might be able to improve it.
https://www.eevblog.com/forum/testgear/the-siglent-sdgx-thread/msg/#msg
Avid Rabid Hobbyist.
Some stuff seen @ Siglent HQ cannot be shared.
PA0PBZ
Re: what should I look for when buying function generator?
«
Reply #2 on: December 20, , 12:43:20 pm »
Excuse me saying this but if you have no idea what to look for, do you really need one?
If you do need one you must have an idea what you want to use it for and then you have a starting point: "Can it do what I want to use it for?"
Tell us why you want one and then maybe we could give you some advice.
Keyboard error: Press F1 to continue.
jpb
Re: what should I look for when buying function generator?
«
Reply #3 on: December 20, , 01:03:01 pm »
The approach I took was to decide what sort of frequency range I might want to go up to in my electronics and then I kitted my lab out (gradually) with appropriate kit.
So I decided I wouldn't be doing GHz rf stuff but might want to run things up to around 50MHz at most. To look at 50MHz square waves (say clocks) needs a scope that can show 3rd harmonic and perhaps 5th harmonic without too much attenuation so I (a bit extravagantly) went for a 350MHz scope but my signal generator is the Agillent one that goes to 30MHz including square waves.
Apart from bandwidth you need to decide whether or not you're bothered by jitter, whether you want low phase noise at audio frequencies, if you will want more than one channel and whether you might want to play back long arbitrary waveforms or perhaps have short pulses spaced by large intervals (which can be problematic for some signal generators). Do you want to have modulation and different wave shapes (square, triangular, arbitrary as well as sine)?
It is worth reading up about how these things work - an article I found most helpful was :
http://www.edn.com/design/test-and-measurement//09-01-98-Choosing-a-waveform-generator-The-devil-is-in-the-details
I don't know if the link is working but Google the title. There are also many guides from Agilent/Keysight and B&K Precision on line.
nctnico
Re: what should I look for when buying function generator?
«
Reply #4 on: December 20, , 01:26:54 pm »
IMHO you can't go wrong with the Feeltech FYS as a first function generator. Even if you decide to buy a more fancy generator later on it will stay handy to have around.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
nour
Re: what should I look for when buying function generator?
«
Reply #5 on: December 20, , 03:16:09 pm »
Excuse me saying this but if you have no idea what to look for, do you really need one?
If you do need one you must have an idea what you want to use it for and then you have a starting point: "Can it do what I want to use it for?"
Tell us why you want one and then maybe we could give you some advice.
I am creating my own lab and I am buying the basic insterments
for the fun. gen, I used one before 15 years ago and it was very simple some knobs and buttons I remember it was 1 megahertz so I know what was function generator used to be
for know I need to know more about modern function generator what do they provide so I can decide
For know I am intersted in digital electronics, power circuits and building test equipments
I don't want a brand name, I want some basic guidelines for deciding my self, after that I will as you guys to recommend one for me
thanks
if what I have wrote doesn't make sense for you or you think there is something wrong, please correct me, I am still beginner and what I know probably less than what you know
nour
Re: what should I look for when buying function generator?
«
Reply #6 on: December 20, , 03:19:19 pm »
The approach I took was to decide what sort of frequency range I might want to go up to in my electronics and then I kitted my lab out (gradually) with appropriate kit.
So I decided I wouldn't be doing GHz rf stuff but might want to run things up to around 50MHz at most. To look at 50MHz square waves (say clocks) needs a scope that can show 3rd harmonic and perhaps 5th harmonic without too much attenuation so I (a bit extravagantly) went for a 350MHz scope but my signal generator is the Agillent one that goes to 30MHz including square waves.
Apart from bandwidth you need to decide whether or not you're bothered by jitter, whether you want low phase noise at audio frequencies, if you will want more than one channel and whether you might want to play back long arbitrary waveforms or perhaps have short pulses spaced by large intervals (which can be problematic for some signal generators). Do you want to have modulation and different wave shapes (square, triangular, arbitrary as well as sine)?
It is worth reading up about how these things work - an article I found most helpful was :
http://www.edn.com/design/test-and-measurement//09-01-98-Choosing-a-waveform-generator-The-devil-is-in-the-details
I don't know if the link is working but Google the title. There are also many guides from Agilent/Keysight and B&K Precision on line.
that was very helpful
thanks a lot
if what I have wrote doesn't make sense for you or you think there is something wrong, please correct me, I am still beginner and what I know probably less than what you know
Tom45
Re: what should I look for when buying function generator?
«
Reply #7 on: December 20, , 04:10:46 pm »
The frequency range is important, both maximum and minimum frequency.
Also think about whether you might need two output channels or just one. And what maximum output voltage would you want.
I was about to buy a Rigol function generator until I realized that its 10 volt maximum output was only for channel 1. Maximum for channel 2 was only 3 volts. So I got the Rigol DG instead because I needed 2 channels with 10 volt maximum.
TAMHAN
Re: what should I look for when buying function generator?
«
Reply #8 on: December 20, , 04:51:42 pm »
Well, I can say nothing bad about my TEK AWG.
For me, the reason why I like it so much is that it has a very cool user interface. I do a lot of work with superimposed sine waves...and being able to generate one with the GUI (aka without the PC) is worth a lot to me.
Re price; I lucked out and got mine for 200 bucks. The case cant be opened due to dents and the NVRAM is fucked, but I stuck in a floppy for waveform storage between sessions and am a happy camper for now.
Re the Chinese: never had one. But I never bought Chinese for large instruments...and while most of my AliExpress orders worked for some time (eventually, every supplier starts to fuck up)...I would not buy a SigLent. Hell, I am even paranoid about Rigol even though their (sometimes VERY asinine) distro lives next door and is fluent in German and English.
Feel like some additional tamile wisdom? Visit my YouTube channel -> https://www.youtube.com/user/MrTamhan for 10min tid-bits!
Smith
Re: what should I look for when buying function generator?
«
Reply #9 on: December 20, , 07:01:40 pm »
I like trigger outputs (for scope triggering), and 10MHz reference in/outputs for devices with less stable clocks. Also trigger inputs can come in handy, so you can start a slow ramp/triangle at an digital input for example.
What I like for testing filters and amps is a frequency sweep. I have 2 FG's with sweep options, and I use them quite frequently.
Its your call if you want/need RS232/USB/LAN/GPIB etc. It can come in handy for automated measurements.
Trying is the first step towards failure
Fungus
Re: what should I look for when buying function generator?
«
Reply #10 on: December 20, , 08:03:41 pm »
a) Write down what you need from a function generator, and why you want one.
b) Find one that matches that specification, at a price you're happy with.
That's it.
If you're not sure about (a) then better not buy one yet. Get a $10 AD module on eBay and play with that.
http://www.ebay.com/sch/i.html?_nkw=ad
You need an Arduino or similar to control it, there's dozens of downloadable programs on the 'net.
nour
Re: what should I look for when buying function generator?
«
Reply #11 on: December 20, , 10:35:53 pm »
a) Write down what you need from a function generator, and why you want one.
b) Find one that matches that specification, at a price you're happy with.
That's it.
If you're not sure about (a) then better not buy one yet. Get a $10 AD module on eBay and play with that.
http://www.ebay.com/sch/i.html?_nkw=ad
You need an Arduino or similar to control it, there's dozens of downloadable programs on the 'net.
very helpful thanks, but I don't think I am willing to buy the module that you have mentioned
I want a real one not something to play with, and I have mentioned the fields that I am intersted in
no specific task to have function generator, thats part of building my lab
and btw I don't think I will spend much on it, just something decent for now
thanks
if what I have wrote doesn't make sense for you or you think there is something wrong, please correct me, I am still beginner and what I know probably less than what you know
nour
Re: what should I look for when buying function generator?
«
Reply #12 on: December 20, , 11:04:36 pm »
After searching about the topic on google (thanks to jpb) I have found this article
http://www.bkprecision.com/support/downloads/function-and-arbitrary-waveform-generator-guidebook.html
very very good article about exactly what I was looking for
I encourage everyone to give it a try, it is very helpful for people like me who have a basic understanding of function generator insterment
I think after reading this article I will have a very good understanding and will help me to decide what I am looking for, at least will clear some fog
one thing though it didn't tell me about is what should I avoid when choosing function generator
what makes a function generator distinguished from another one, I am not talking about the max frequency range or the features, but I am sure there is other factor, may be the noise or other stuff that I am not aware of
if what I have wrote doesn't make sense for you or you think there is something wrong, please correct me, I am still beginner and what I know probably less than what you know
cs.dk
Re: what should I look for when buying function generator?
«
Reply #13 on: December 21, , 08:11:51 am »
I'm a newbee too, but i thought i would chime in.
I've been building my self a little "hobby-lab", just to learn electronics and repair simple stuff. One thing that i have noticed is, multimeters and powersupplys, you can't have enough of them. (with some decent probes/test leads). I've got some good handtools, a decent soldering iron, and a DSZ.. A function gen would be one of the last thing i'm gonna buy, unless some specific task forces me to do so.
IMO there is a lot of other stuff, that are worth spending money on, to get started. Buy a FG when you actually have a need for it.
Just my 2c
TAMHAN
Re: what should I look for when buying function generator?
«
Reply #14 on: December 21, , 09:22:11 am »
About my TEK AWG (which I really like). I bought it cause: a) cheap and b) had excess loot to burn for tax reasons.
I have built MULTIPLE DDS/AWG units with an MCU, some Opamps and shit. Doing so is a very interesting learning exercise...and if a) and b) werent met, i would probably still do so
Feel like some additional tamile wisdom? Visit my YouTube channel -> https://www.youtube.com/user/MrTamhan for 10min tid-bits!
Smith
Re: what should I look for when buying function generator?
«
Reply #15 on: December 21, , 12:47:10 pm »
IMO there is a lot of other stuff, that are worth spending money on, to get started. Buy a FG when you actually have a need for it.
Indeed, I managed to do 10 years without any FG. Yes it's handy, but I've always managed by building some circuit to fulfill the (temporary) need.
Only reason to go get one immediately is for audio purposes. It's so easy to check amps, filters and such.
Trying is the first step towards failure
jpb
Re: what should I look for when buying function generator?
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Reply #16 on: December 21, , 08:04:05 pm »
one thing though it didn't tell me about is what should I avoid when choosing function generator
what makes a function generator distinguished from another one, I am not talking about the max frequency range or the features, but I am sure there is other factor, may be the noise or other stuff that I am not aware of
Most modern function generators (at least the ones that do different wave shapes) are DDS. These are good for sin waves given the right filters. They are good for square waves where the frequency fits in with the memory and the natural cycle of the instrument - where it doesn't you can get a lot of jitter. Keysight/Agilent have a good (but expensive) approach to sorting this. Siglent have what looks like an effective solution for pulses. The thing to look out for is can they have a fast rising edge with slow pulses? If you have a short pulse stream but with a long gap between them can it get uniform pulse widths?
Another area DDS generators (as apposed to the old analogue ones) is in triangular waves. You will notice that the frequency specs for these is much lower than for sin or square waves - you need a lot of harmonics to get a good sawtooth.
The third thing to look out for is amplitude vs frequency. In the old days generators went up to a given amplitude (say 10V p-p) for a given bandwidth. But Rigol (I think it was) introduced increased bandwidth but at lower amplitude. The output amplifier has a gain-bandwidth product so by switching in a lower gain you can go to a higher bandwidth. In some ways it is a bit of a cheat but even Keysight/Agilent are following suit otherwise they can't compete on spec sheets. It is not entirely a con - it is useful to be allowed higher frequencies as long as you're aware that you perhaps can only go to 1Vp-p.
The cheaper generators also tend to have more phase noise or harmonics though I think having an external clock reference can help. If you look on the Siglent thread (I forget the model number) on this forum you'll see some measurements taken on a spectrum analyser which are compared to (much better) output of an old bit of HP kit.
alank2
Re: what should I look for when buying function generator?
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Reply #17 on: December 29, , 01:42:19 pm »
I started with those small pcb based ones from ebay where you have a display and can adjust the signal type, amplitude, etc. They also have a TTL type square wave output. While they would get me out of a bind like bricking an AVR by changing the fuses to use a clock when there wasn't one, it falls so short to a decent AWG.
I bought a SDGX a few months ago and it is so much more capable. Knowing what I know now, there is no way I'd spend $100 on a small board or cheaper AWG when for $469 after discount you can get a SDGX that can easily go to 120 MHz sine by simply using an arbitrary wave file. The value and capability are so much higher.
bithead9
Re: what should I look for when buying function generator?
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Reply #18 on: January 01, , 06:48:59 am »
I picked up this unit off Ebay as a starting point. Been using it to tune the IF and basic 3MHz and less for AM radio repairs. UDBS Function Signal Generator Source Frequency Counter DDS Module Wave 5MHz - http://www.ebay.com/itm/UDBS-Function-Signal-Generator-Source-Frequency-Counter-DDS-Module-Wave-5MHz-/? for $34.00 you cannot beat that!
oldway
Re: what should I look for when buying function generator?
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Reply #19 on: January 01, , 08:28:36 am »
I have two units pm Philips and, in my opinion, they have everything anyone could want from a function generator.
http://www.surplus-electronics.co.uk/index.php/en/Products//
Detailed characteristics are described in the manual you can download here:
http://elektrotanya.com/philips_pm_sm.pdf/download.html
This can serve as basic criteria for a good function generator.
billfernandez
Re: what should I look for when buying function generator?
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Reply #20 on: January 01, , 05:35:32 pm »
Nour:
For your purposes you will at least have to make some guesses about what range of projects you think you might engage in. In that light, you should look at:
o cost: Buy something cheap just to get started, or buy something more expensive that you think might give you more long-term flexibility?
o frequency range: Audio (say 40kHz), Bluetooth (2.4GHz), wireless remote control (412 or 900 MHz)?
o frequency accuracy.
o waveform fidelity, noise, distortion.
o jitter. timing accuracy.
o voltage and current drive capability.
o waveforms: Function generators started out being sine, triangle and square wave because they were easy to generate with analog technology. Sine and square continue to be commonly needed. But these days there's also often the need for pulse trains, digitally-encoded signals, modulated waveforms (AM, FM, PWM, etc.) and for "complex" waveforms such as would be found in EEGs, seismic sensors, etc. In all these latter cases having arbitrary waveform generation capability is convenient.
o Might you ever want to control the generator by computer? To download complex waveforms or digital pulse streams? To coordinate a test setup with other equipment under computer control? In these cases it's useful to be able to connect via Ethernet, and use SCPI commands to control the unit.
o User interface. I find it a lot easier to punch buttons and get exactly what I want (digital, computer controlled generator) then to carefully twist knobs and read frequency and voltmeters to get what I want (analog controlled generator).
For what It's worth, I recently bought a Siglent SDGX because I wanted a general purpose function generator that would very versatile, be of good quality, have good performance, could be used for a wide variety of things, be easy to use, and that I could afford. I think this was a good choice for me, but then I could afford $500 for a general-purpose signal source, and I don't do any RF work where I'd need much higher frequencies.
« Last Edit: January 01, , 06:07:43 pm by billfernandez »
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