Function Generators

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  • Last Post 27 December 2018
Chris posted this 08 May 2017

For discussing Function Generators, Makes Models Prices, and How To's / Best Practices

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pat1 posted this 11 May 2017

Hi Chris,

Thankyou for creating this equipment thread.  I ended up ordering a (immitation?) Feeltech FY3224S function generator and a 500w single channel hifi amp (IRS2092S) off ebay to start with.  Didn't wanna break the budget since I spent a bit more on the Oscilloscope  Not too expensive and lots of information available about this function generator on the net.  Something I have learned from 3d printing is to buy a toy everybody else has so come time for equipment problem solving the forums are an invaluable source of information.

cheers

Pat

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Chris posted this 11 May 2017

Hi Pat1 - Nice! We are very spoiled today with High Tech Equipment and excellent prices!

I also think the same, no point spending too much, it becomes a waste of money very quickly! Better off to get something that is affordable and usable.

   Chris

Fighter posted this 12 May 2017

Hi Pat1, it's exactly the model I have, please do not ignore the mini-cd from its box, if you install the software from it I think you'll be very pleased to find out you can control it from pc/laptop in real-time from the software interface through USB (see mine in action here: http://imgur.com/a/z121o)

Unfortunately the audio amplifier I bought seems to not work properly, the signal generator is sending correct signals to the amplifier's input (I verified this with my oscilloscope) but the output of the amplifier is always sine wave on both channels. 

Cd_sharp (he have the same function generator model) gave me another solution, a elegant one, to use on signal generator's outputs two MOSFETs which will drive the current provided by the power source, so I'll give up on using this audio amplifier and I'll build the MOSFET solution.

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pat1 posted this 13 May 2017

Hi Aurel, thanks for the tip about the disk.  When I was sourcing the FY3224s from within Australia I made sure to purchase one that sold it with the disk as a lot of them don't.  I thought the software might be handy.

I have also purchased two low cost class D audio amps.  One locally and one from china.  I'm guessing they will behave the same way as your amp - ie only outputs sinwave regardless of what signal you feed them.  When i get them i will do a test and let you know.

Chris - is the transistor MJL21194G of any use for any of the simple starting experiments here?  I bought a box of 100 from china a few years ago when i got excited about Bedini's work.  They cost less than $2 each so I can't vouch for their quality.

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Chris posted this 13 May 2017

Hi Pat1 - Not sure, I would say so, we are not High Frequency, 100GHz or anything, so no real problem for most Fets/Transistors.

Might be worth a check on the Datasheet for the MJL21194G - To me it looks fine.

The experiments each of us decide to do, are the decision of our own making. However, I would think about making another experiment also, can be a bit tricky and also needs a degree of understanding: The Wistiti POC Toroid

This is the same ideas and works as we have already talked, but in my opinion very much easier to get to a working state. Sometimes this works really easy, but you need to understand the whys and whats to be able to achieve the goal. Critical to see Opposing Fields.

Again some work is needed, a lot of understanding, but achievable!

Supporting Material:

Electrical Energy - What is it?

Magnetic Modulation of Charged Particles

   Chris

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Fighter posted this 13 May 2017

I have also purchased two low cost class D audio amps.  One locally and one from china.  I'm guessing they will behave the same way as your amp - ie only outputs sinwave regardless of what signal you feed them.  When i get them i will do a test and let you know.

Not necessarily, Pat1. I saw on internet many people are using audio amplifiers on their function generators so I guess I just found one which is not working properly with a function generator, that's all. I really hope you're more lucky than me and your amplifiers will work !

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parkham posted this 12 June 2017

So... is 2Mhz "good enough" for most everything that one might want to experiment with down the road or?

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Zanzal posted this 13 June 2017

2MHz sounds fine to me. I went with a 25MHz sine / 6MHz non-sine MHS-5225A at around $50 delivered which is total overkill for anything I plan to do.

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Chris posted this 13 June 2017

@Fighter, Parkham and Zanzal - 2MHz is more than enough to start with, for sure.

The Function Generator Amplitude is important when driving an Audio Amplifier! Too much amplitude and the Wave will go Squarish, and loose its Sine Wave shape, often a bad thing! Something we don't want!

Turn your Function Generator amplitude down until the wave goes back to sine, monitor the Audio Amp's output on the scope.

There is a lot of nitty gritty to this, Output and Input Impedance and so on, but the basic how to's are there to get a nice Sine Wave.

   Chris

 

P.S: Sorry for the late reply!

Zanzal posted this 27 December 2018

In another thread Wistiti asked about function generators. I just finished researching this subject and for budget these are the main choices:

1) $5 XR2206 based function generator (has sine wave for use with amplifier)

2) $20 FG-100, an upgraded version of the above with a display (probably not worth it)

3) $65+ JDS6600 (depends on model), all these are good for the price, IMO the one you are willing to pay for is the best one. (recommended for best value)

4) $132 A Hantek 2D42 3 in 1, an oscilloscope, FG, and multimeter combo starting at $132, don't use the included probes unless you are wanting to analyze very low signals instead  buy two 2KV 100X probes ($11 ea).  At 1X it has 150Vrms limit so using the higher voltage probes should give some safety up to 700V-800V. I may be totally wrong as that's a guess on my part. In fact that is the only reason I haven't bought one in that I don't know for sure what the safe voltage range would be exactly, too low and its just not suitable for anything I mess with. Read the datasheet closely, before choosing this option. Its a handy device but with limits.

All prices are US via Aliexpress, but sometimes Amazon sellers will sell near the same price. You almost can't go wrong with the lowest tier JDS6600 (or even a few tiers up). Just keep in mind it is a cheap product. That could be a good thing since if you damage it its less painful.

Also I found a cheap amplifier FPA0510S which is good up to 50kHz and 20Vpp 1amp.  It hasn't arrived yet, but I plan to use it with sine generator. No idea if its any good, but for $20 I'll try it out.

For square waves, I just bought some 12A TC4452 mosfet drivers  which very well may be powerful enough to drive loads directly through a 2ohm resistor at up to 18 volts. A gate driver is probably not really needed for the JDS6600 but will probably be needed for all the others at some point (for mosfets/igbt that are not logic level or for faster rise/fall times).

All the above are great starting choices depending on the budget. Above that its really difficult to choose, and given the higher prices its a personal choice with a sizable investment. I like the DG900 series from Rigol but they are not cheap.

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Ere many generations pass, our machinery will be driven by a power obtainable at any point of the universe. This idea is not novel. Men have been led to it long ago go by instinct or reason. It has been expressed in many ways, and in many places, in the history of old and new. We find it in the delightful myth of Antheus, who drives power from the earth; we find it among the subtle speculations of one of your splendid mathematicians, and in many hints and statements of thinkers of the present time. Throughout space there is energy. Is this energy static or kinetic? If static, our hopes are in vain; if kinetic - and this we know it is for certain - then it is a mere question of time when men will succeed in attaching their machinery to the very wheelwork of nature.

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