Author Topic: Looking for good cheap Function Generator  (Read 19394 times)

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Offline WakeUpWolfgang

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Looking for good cheap Function Generator
« on: June 25, 2013, 02:01:55 pm »
I have a very limited budget and need a function generator I do speaker repairs. I need to run a sine wave through a speaker and adjust the frequency  so I know what ranges are not working. I don't have a function generator and was looking at the DG1022 from Rigol.

Is it any good? Is it like the DS1052E in build quality vs price?
 

Offline c4757p

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Re: Looking for good cheap Function Generator
« Reply #1 on: June 25, 2013, 02:04:43 pm »
From what I've seen it's quite good, but serious overkill for running a sine wave through a speaker. Literally any FG will do audio frequency sines.
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Offline Stonent

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Re: Looking for good cheap Function Generator
« Reply #2 on: June 25, 2013, 02:07:56 pm »
Sounds like overkill. You can already do that with cheap audio software and a PC sound card.
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Offline Mechatrommer

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Re: Looking for good cheap Function Generator
« Reply #3 on: June 25, 2013, 02:31:29 pm »
Is it any good? Is it like the DS1052E in build quality vs price?
its good but its overkill and "non-optimum" for the purpose you stated. but hey if you can afford it why not? it can do alot more. but for your job, if you are doing hundreds of speakers at a time, you need something with analog trimpot to adjust freq very quickly. we can suggest either the DIY one or the ready made like you proposed, but we cant since we dont know your background, skill and tools ;)
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Offline WakeUpWolfgang

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Re: Looking for good cheap Function Generator
« Reply #4 on: June 25, 2013, 02:43:32 pm »
I do have other needs for one but been getting by I am mostly using this as an excuse to get one but I can't afford too much.

I know I can do it with some DIY kits or my my own really cheap but when you are working on speakers that are $1500+ each you are really concerned with liability. I don't want to get blamed for breaking it because I did not use a "real" function generator. There are a lot of people that come to me who don't  like anything DIY for repairs and like to point the finger.

I do more then speaker repair I do everything from installing security and fire systems, sound systems and repairing security systems  fire systems, sound systems and Amps. Also make some small electronics if we can't find it on the market.
 

Offline don.r

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Re: Looking for good cheap Function Generator
« Reply #5 on: June 25, 2013, 02:55:36 pm »
Buy an old Wavetek from the 70's. They look the business and will do everything you need. Easy to repair as well.
 

Online nctnico

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Re: Looking for good cheap Function Generator
« Reply #6 on: June 25, 2013, 03:25:51 pm »
I have a Siglent SDG1010 (with Lecroy firmware) and I'm very happy with it.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline dfmischler

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Re: Looking for good cheap Function Generator
« Reply #7 on: June 25, 2013, 03:46:32 pm »
I got a BK 3011B 2 MHz function generator for $40 on ebay.  Here is a manual for it (402KB pdf).  I paid a bit more for an HP 8111A 20 MHz pulse/function generator.
 

Offline Anson

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Re: Looking for good cheap Function Generator
« Reply #8 on: June 25, 2013, 04:09:00 pm »
Buy an old Wavetek from the 70's. They look the business and will do everything you need. Easy to repair as well.

 :-+

Or a Dana Exact. Less than a $100 easy to fix and work great.
 

Offline saturation

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Re: Looking for good cheap Function Generator
« Reply #9 on: June 25, 2013, 04:22:13 pm »
Since you're in the USA, I'd recommend looking at a used Global Specialties FG.  For these reasons:

They are often used in trade schools, and built like tanks
It was first designed in the 1980s, and still made nearly unchanged, to this day
The 1980-1999 ones are dirt cheap and made when ICs were made with higher quality than today; they last "forever"
The older models are made in Taiwan, who overall, still do better QC than PRC devices
They are easy to repair, if ever need be
typically sold used for $20-$50, S&H included

Cons
These are analog FG, and have higher distortion and frequency instability typical of analog frequency generation

http://www.ebay.com/itm/GLOBAL-SPECIALTIES-2001A-FUNCTION-GENERATOR-SINE-SQ-TRI-200-KHZ/231002423522?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D261%26meid%3D8629273829926417366%26pid%3D100005%26prg%3D1088%26rk%3D2%26sd%3D121123993969%26

http://www.ebay.com/itm/GLOBAL-SPECIALTIES-2002-FUNCTION-GENERATOR/121123993969?_trksid=p2045573.m2102&_trkparms=aid%3D555003%26algo%3DPW.CAT%26ao%3D2%26asc%3D277%26meid%3D8629254251381961189%26pid%3D100034%26prg%3D1079%26rk%3D1%26sd%3D390565912871%26

http://globalspecialties.com/test-equipment/generators.html

If you need a new one, general purpose, I still highly recommend the GW Instek SFG-1003, I use it very often.

Its output frequency is ppm stable, low distortion down to ~ -50dB.  Not "audiophile" quality, but that's a whole other issue  :phew:

Cons
No sweep or modulation
No voltage controlled oscillator

http://www.tequipment.net/InstekSFG-1003.html

$145 sale price, $5 cheaper than when I paid list for it at $150  ;D

Best Wishes,

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Offline WakeUpWolfgang

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Re: Looking for good cheap Function Generator
« Reply #10 on: June 25, 2013, 05:52:23 pm »
Thank you for all of the suggestions. I will go over all of them later today. 
 

Offline Radio Tech

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Re: Looking for good cheap Function Generator
« Reply #11 on: June 25, 2013, 05:55:55 pm »
I am in need of one also to play around with different scopes. But I am a tight a$$. Really thinking about  one of the free programs to run from sound card but have not seen one that works decent yet. if someone has tried one that works good please post  up a link.

Also thinking of building something along the lines of a 555 timer chip.

Offline WakeUpWolfgang

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Re: Looking for good cheap Function Generator
« Reply #12 on: June 25, 2013, 06:14:19 pm »
I am in need of one also to play around with different scopes. But I am a tight a$$. Really thinking about  one of the free programs to run from sound card but have not seen one that works decent yet. if someone has tried one that works good please post  up a link.

Also thinking of building something along the lines of a 555 timer chip.

I am too so I am trying to get my business to buy one so I don't to and want to take the paperwork to them saying this is what you need and why.  But if I could build my own for my self that would be really cool.
 

Offline Winston

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Re: Looking for good cheap Function Generator
« Reply #13 on: June 25, 2013, 06:57:01 pm »
I have a very limited budget and need a function generator I do speaker repairs. I need to run a sine wave through a speaker and adjust the frequency  so I know what ranges are not working. I don't have a function generator and was looking at the DG1022 from Rigol.

Is it any good? Is it like the DS1052E in build quality vs price?
For what you need to do, this would probably suffice.  It's already built, not a kit, and can "generate frequency sweeping signals of selected waveforms, start frequency, stop frequency, and sweep rate can be independently set."  Very simple and intuitive to operate (I own one):

http://www.ebay.com/itm/Paneled-Portable-miniDDS-Digital-Function-Generator-Servo-Controller-DDS-USA-/160708631160?pt=LH_DefaultDomain_0&hash=item256afb1a78

More tech details:

http://www.jyetech.com/Products/085/e085.php

YouTube reviews:

https://www.youtube.com/results?search_query=fg085+function+generator
« Last Edit: June 25, 2013, 06:59:49 pm by Winston »
 

Offline dfmischler

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Re: Looking for good cheap Function Generator
« Reply #14 on: June 25, 2013, 07:03:13 pm »
I am in need of one also to play around with different scopes.

I suggest that for scope evaluation the best thing is to have a fast rise time on the square wave.or pulse waveform.  Sub-nanosecond if possible.  You might need a device just for fast rise time pulses separate from your function generator.
« Last Edit: June 25, 2013, 08:06:10 pm by dfmischler »
 

Offline Radio Tech

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Re: Looking for good cheap Function Generator
« Reply #15 on: June 25, 2013, 07:17:15 pm »
I am in need of one also to play around with different scopes.

I suggest that for scope evaluation the best thing is to have a fast rise time on the square wave.or pulse waveform.  Sub-nanosecond if possible.  You might need a separate device just for fast rise time pulses separate from your function generator.

I agree. Especially when repairing scopes so you get things spot on. Guess I will have to bite the bullet and invest in a decent one.
In the mean time I am going to play around with some PC based ones. Here is a screen shot of one I found connected to my Owon.
« Last Edit: June 25, 2013, 07:21:25 pm by Radio Tech »
 

Offline rsjsouza

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Re: Looking for good cheap Function Generator
« Reply #16 on: June 25, 2013, 07:17:29 pm »
Buy an old Wavetek from the 70's. They look the business and will do everything you need. Easy to repair as well.
+1 for the Waveteks... They do the job flawlessly.

For a cheap one, check here.

When repairing audio equipment I also used some pre-recorded waveforms and a netbook as a playback device (not ideal, but I wasn't reparing $1.5k gear). Some useful pages for that are here and this excellent page with pre-recorded test tones
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Offline don.r

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Re: Looking for good cheap Function Generator
« Reply #17 on: June 25, 2013, 08:25:13 pm »
Buy an old Wavetek from the 70's. They look the business and will do everything you need. Easy to repair as well.
+1 for the Waveteks... They do the job flawlessly.

For a cheap one, check here.

When repairing audio equipment I also used some pre-recorded waveforms and a netbook as a playback device (not ideal, but I wasn't reparing $1.5k gear). Some useful pages for that are here and this excellent page with pre-recorded test tones

That looks like a nice one in that it has sweep as well.
 

Offline WakeUpWolfgang

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Re: Looking for good cheap Function Generator
« Reply #18 on: June 25, 2013, 09:12:11 pm »
Did Dave do a video comparing different  function generators? If not I think it would be a good VBlog. I bet there are more people out there who would like to get one but do not know what to look for in a good function generator.
 

Online nctnico

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Re: Looking for good cheap Function Generator
« Reply #19 on: June 25, 2013, 09:50:45 pm »
I'd stay away from the old RC generators unless when very low on money. In the end the buttons stop working and the pots get noisy.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline c4757p

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Re: Looking for good cheap Function Generator
« Reply #20 on: June 25, 2013, 10:01:25 pm »
I'd stay away from the old RC generators unless when very low on money.

Many of them are complete pieces of crap, too. I've got an old Simpson that's suppose to do sine, square, triangle to 5 MHz. Once you hit about 2 MHz, triangle becomes sine, sine becomes "WTF is this?", and square becomes "heavily distorted sine". Amplitude, frequency and symmetry controls are so ridiculously nonlinear that you spend a very long time fighting with the controls (and there's interaction between the latter two), and the sweep and modulation are so bad that they're useless. I was able to make it usable for very limited purposes by modifying the circuit in a few spots, but it's still worse than the cheapest shit imported via fleaBay.

Don't let yourself think that just because it's been around for a while, looks good and has a recognizable name that it will even meet its shitty specs.
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Offline WakeUpWolfgang

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Re: Looking for good cheap Function Generator
« Reply #21 on: June 25, 2013, 10:39:35 pm »
Don't let yourself think that just because it's been around for a while, looks good and has a recognizable name that it will even meet its shitty specs.

That is why I started this I wanted to know if the Rigol DG1022 is any good.
 

Offline mickpah

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Re: Looking for good cheap Function Generator
« Reply #22 on: June 26, 2013, 01:30:55 am »
HI
I've been looking for one too. John boxall did this review
http://tronixstuff.wordpress.com/2013/02/06/kit-review-jye-tech-fg085-dds-function-generator/

Looks ok for basic audio, but would be good to see it put to real test. but for less than  $50 ...
 

Offline WakeUpWolfgang

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Re: Looking for good cheap Function Generator
« Reply #23 on: June 26, 2013, 02:02:31 am »
I talked to my boss and he said if he lets me buy one it will need to have AM, FM and Sweep waveforms.
 

Offline sportq

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Re: Looking for good cheap Function Generator
« Reply #24 on: June 26, 2013, 01:57:22 pm »
Have you thought about the Digilent Analog Discovery? For $99 (depending where in the world you are) you get a good quality 5Mhz Function Generator and an Artibtary Waveform Generator, with a 10Mhz scope and logic analyser thrown in. I've had one for about a month and I can't stop playing with it, totally blown away.

The downside might be that it is PC based so it's not instant on and not portable (well, connected to a laptop it is).

Peter
 


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