Author Topic: Function Generator question  (Read 1693 times)

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Offline mmilejski

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Function Generator question
« on: June 27, 2013, 05:25:04 pm »
Hi,

I got a function generator and oscilloscope recently and I am wondering about the connecting cables. Does function gen also need some capacitance compensating like an oscilloscope when I want it connected to a breadboarded circuit? (I guess not, but asking does no harm)
How do you guys connect your function gens to circuits? Do you have some BNC -> crocodile clips adapters?
 

Offline KJDS

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Re: Function Generator question
« Reply #1 on: June 27, 2013, 07:07:23 pm »
There's no need to compensate, however it is possible that if you're not driving a 50 ohm load then some ringing could occur. Usually I'll put a BNC socket onto the breadboard and connect the cable to that. Sometimes I'll have a ground cable and clip from the socket body to provide a ground and then press the centre pin onto the point I want to inject the signal into.

Offline Mechatrommer

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Re: Function Generator question
« Reply #2 on: June 28, 2013, 12:24:15 am »
for the start... search, download and read AN47.pdf (High Speed Amplifier Techniques)
- Unterminated Pulse Generator AN47-7
- Poorly Terminated Line AN47-8

if you have more spare time, search for member like w2aew and jahonen etc and look out for precious gems in their posts. they are very sharp at the physics of this subject, also they have website and videos. above all... practice. trust me the gems are meaningless without practising it, you wont get it at the first sight. hope it helps.

edit: ei i forgot the real question... yes, for few tens MHz work and above you need BNC, coax, termination, pain and suffering...

Q: Does function gen also need some capacitance compensating like an oscilloscope?
A: depends on your connection, long coax needs compensation aka terminator at the end. Jim said, the best probe is no cable at all, so possibly no need terminator but... it depends.

Q: How do you guys connect your function gens to circuits?
A: coax cable and termination, some time direct to BNC connector on the board, alligator clips if the signal is slowish and again... it depends.

Q: Do you have some BNC -> crocodile clips adapters?
A: oh yes we have a lot, some by intention most by mistake, collected during a long span of time. variety of brands and mods ;)

ei and for the last edit, an advice... also make sure you have a solid PSU, the best is non-faulty LA battery for low power circuit. whacky PSU is quite enough to get you into hair loss problem.
« Last Edit: June 28, 2013, 12:44:29 am by Mechatrommer »
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline mmilejski

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Re: Function Generator question
« Reply #3 on: June 29, 2013, 12:02:03 am »
Thank you for your answers.

I always thought of Application Notes as a documents regarding specific ICs, it seems that all those app notes are great source of useful information. Is there anywhere on the internet some list with worthwhile app notes like this AN-47?

I hope to get much practice now that I will have 3 months long vacation. Before I got myself an oscilloscope I was using SPICE to simulate my "ac circuits" and all I did on my breadboard were "dc circuits".

For now I won't exceed those tens of MHz you said about but for when I will I have got a lead-acid battery ripped out of an UPS to act as a noise free power source.
 

Offline Mechatrommer

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Re: Function Generator question
« Reply #4 on: June 29, 2013, 04:41:16 am »
I always thought of Application Notes as a documents regarding specific ICs, it seems that all those app notes are great source of useful information. Is there anywhere on the internet some list with worthwhile app notes like this AN-47?
its quite difficult to list them all, others may give other suggestion. google high speed circuit, google chracteristic impedance, google anything. while practising you'll know what you want to look for, your practice will guide you, different man different problem. ;)
For now I won't exceed those tens of MHz.
why not? its fun experimenting! the mistake you made, the misteries and all, when learnt will stick hard in your memory. not like if i tell you some secret today, you may forget it by tomorrow ;)
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 


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