Help with selecting new equipment - signal generator - Page 1
Forum section: electronics / beginners

author: 妖怪女
author_rank: Newbie
timestamp: December 05, 2021, 05:43:08 am
content: I am new to electronics and I would like a signal generator that could perform a sweep that can be controlled by a jog dial. For instance I want to set the range from 1Hz to 20kHz and then use the dial to move back and forth along this frequency range - perhaps in a logarithmic interval or in a specified interval. A linear or fixed increment is okay though.Is there such a thing? Is any of this a common feature of digital signal generators?Optimally, I would like a generator that can do this and that I can mate to an oscilloscope and also generate bode plots, but this isn't necessary.I was hoping to spend ~$200-$300USD for the generator, but I can spend more if needed.Thank you for any help or suggestions!

author: bob91343
author_rank: Super Contributor
timestamp: December 05, 2021, 06:31:08 am
content: This is common. You need a function generator or a sweep generator, sometimes called an AWG (arbitrary wave generator). Most modern ones can do what you want; you needn't spend a whole lot.

author: ledtester
author_rank: Super Contributor
timestamp: December 05, 2021, 06:46:06 am
content: You can get good function generators for < $200. Have a look at the FY6900, Uni-T UTG962 or the Juntek PSG9080. They have been widely discussed on this forum.They all have the capability to perform automatic sweeps in either linear or log fashion. All of them use a rotary encoder to change values such as frequency, phase offset, etc. So you could perform a manual linear sweep with the rotary encoder. A manual log sweep is not directly supported. However, all of these units can be controlled from a computer (or microcontroller over a serial interface) so such a capability could be implemented with a little programming work on your part.Are you only interested in audio frequency wave forms? Perhaps you can just use your computer's sound card. There are a lot of programs to do this -- just do a web search for "sound card function generator".

author: tautech
author_rank: Super Contributor
timestamp: December 05, 2021, 07:16:52 am
content: Quote from: 妖怪女 on December 05, 2021, 05:43:08 amThe scope you have might determine the best fit AWG for your needs.Manually controlling the sweep is unusual although changing the time a sweep might take to repeat is more common.SDG1032X might well suit your requirements.

author: bob91343
author_rank: Super Contributor
timestamp: December 05, 2021, 07:36:07 am
content: ledtester, that link doesn't work. Well it does work but the download doesn't. There seems to be no way to ask for help. Have you downloaded that software?

author: ledtester
author_rank: Super Contributor
timestamp: December 05, 2021, 07:56:11 am
content: Quote from: bob91343 on December 05, 2021, 07:36:07 amNo, I haven't downloaded it myself. I'll change my answer to "search google". There are a bunch of PC programs to do this, e.g.:https://listoffreeware.com/best-free-signal-generator-software-windows/

author: 妖怪女
author_rank: Newbie
timestamp: December 05, 2021, 07:59:41 am
content: Wow! Thank you so much!Quote from: ledtester on December 05, 2021, 06:46:06 amThanks so much! I read these manuals' sweep sections and main wave sections to see if I can figure it out. Should I be in the sweep mode or just wave output mode? It looks like I can start the sweep with the knob, but then it just does the whole sweep automatically. Do you happen to have any of these three machines or any other machine even that can check this? I'm thinking maybe I shouldn't be in the sweep mode. Perhaps I have to do it from the basic output mode and then change the step rate of each turn?Also, my language isn't very good; maybe I asked the question wrong (maybe sweep is the wrong word). In this machinehttps://www.amazon.com/tenma-72-455a-signal-generator-frequency/dp/b008ex8uqqThe dial can go back and forth to any frequency I want and I can "sweep" from one end to the other. It can't do arbitrary waves or other cool things that a digital generator can though...At the moment I am doing audio. I'll do a research on an audio program on pc. This might be a great option!Thanks again so much for your help! I really really appreciate it!edit: Here is a better picturehttps://www.ebay.com/itm/265096280827?hash=item3db8f83afb:g:jpsAAOSw-SpgV4YRQuote from: tautech on December 05, 2021, 07:16:52 amYes this seems to be my concern. I don't want to buy something that won't fit my need :3

author: ambrosia heart
author_rank: Regular Contributor
timestamp: December 05, 2021, 08:04:02 am
content: I am new to electronics and I would like a signal generator that could perform a sweep that can be controlled by a jog dial.Knowing to write 妖怪女,monster girl, may be you knowChinese words. If yes, shop at taobao search type: DDS信號發生器.They are programmable and producing arbitrary waveforms.See photos They are excellent if you are not using them frequently.

author: ledtester
author_rank: Super Contributor
timestamp: December 05, 2021, 08:17:55 am
content: Quote from: 妖怪女 on December 05, 2021, 07:59:41 amAll of the modern function generators allow you to change the frequency with the rotary encoder. The frequency will change by certain delta with each click of the encoder. You can specify the delta to be any power of 10 Hz -- like 1 Hz, 10 Hz, 100 Hz as well as 0.1 Hz, 0.01 Hz, etc.Here is a video showing how the rotary encoder is used to set and change frequency (at timestamp 10:22):FeelTech FY6800 60MHz Signal Generator / Counter Review -- Robert's Smorgasbordhttps://youtu.be/S9usQLFKZLk?t=10m22sNote that the frequency changes immediately when the rotary encoder is turned.

author: 妖怪女
author_rank: Newbie
timestamp: December 05, 2021, 09:59:43 pm
content: Splendid! thanks so much ledtester! You even put a timestamp on it. With the digit overflow, this should work! Thanks again!Thanks to everybody else too~!

author: rstofer
author_rank: Super Contributor
timestamp: December 05, 2021, 10:42:10 pm
content: A knob could be scripted but that's a lot of work. I will still recommend the Digilent Analog Discover 2 because it will generate the sweep signal and start with an external signal.Install the Waveforms software and play around with the WaveGen tool. Change from'Simple' to 'Sweep' and enter the parametersHere's the tool:https://digilent.com/shop/analog-discovery-2-100ms-s-usb-oscilloscope-logic-analyzer-and-variable-power-supply/Here's the software:https://digilent.com/shop/analog-discovery-2-100ms-s-usb-oscilloscope-logic-analyzer-and-variable-power-supply/Here's the Reference Manual:https://digilent.com/reference/software/waveforms/waveforms-3/reference-manualThis device is perfect for lower frequency applications and it's a heck of a lot cheaper than a controllable AWG and two-channel scope with Bode' Plot capability.For voltages outside the capability of the device, you can use the BNC Adapter Board with 10x probes. I bought a pair of FIXED 10x probes from ProbeMaster specifically for use with the AD2.Attached is a Bode' Plot from Waveforms

author: Electro Fan
author_rank: Super Contributor
timestamp: December 06, 2021, 04:07:13 am
content: A signal generator is a pretty useful piece of test equipment and the several models suggested above are all good candidates worth considering. If your work is going to be largely with audio you might be able to get by with software that works with a sound card in a PC. Below is a list of 10 possible programs. I have used TrueRTA (#4) and it was very useful in equalizing the acoustics of a sound system/room combination using the sweep function and other functions. There are several versions from fee to paid depending on the performance needed. These programs won’t be able to do everything the dedicated sig gens do but they are worth a look-see especially with the free/trial download versions.https://boomzi.com/best-audio-spectrum-analyzer-software/#4-truerta

author: Calvin
author_rank: Regular Contributor
timestamp: December 07, 2021, 04:48:50 am
content: Hi,for Audio it'd be quite useful to have a two channel generator with two identical outputs and which can be coupled.Unfortunately the latter is hardly ever specced in datasheets, or what and how the coupling works.A Hantek HDG2102 we have at work for example offers two outputs and a 'couple' button.In reality though its useless since it loses the coupling as soon as You try to change a single parameter!My own Siglent SDG2042 on the other hand allows to couple its identical two outputs by frequency, amplitude and phase etc. in either straight values or ratios.So when You change one parameter on one channel the second follows by the chosen 'offsets'.I doubt that any of the afore praised cheap chinese devices will offer You such functionality and a easy and(!) useable GUI.The Digilent -beeing a lot more than a function generator- or the Siglent SDG1032 will probabely fill the bill very well. At least those are two decent devices.regardsCalvin