Electronics > Beginners
Oscilloscope oddities
Ian.M:
--- Quote from: JohnPen on August 13, 2018, 09:46:36 am ---An extra thought if you have a function generator like the FYxxx series which has 2 separate independent outputs. Using both outputs on say 100 Hz, with 8v sine waves on each, set one output offset by 180 degrees. Connect the 2 outputs to a bridge rectifier's AC inputs, load the output of the rectifier with a 10K load and monitor with your scope.
--- End quote ---
That setup is equivalent to a transformer with a 16V secondary with its center tap grounded. It will give equal positive and negative DC rails out from the bridge rectifier symmetrical with respect to ground, and you myst not ground the bridge rectifier negative terminal. If you only want to demo full wave rectification, *DON'T* use a bridge rectifier. All you need is two diodes, one from each output, cathodes towards the common load.
DannyTheGhost:
I, as an owner of DSO138, suggest you to use DC mode instead. In AC mode input there is capacitor in series, so you won't see any DC part of voltage (in your case, rectified part of your wave).
JohnPen:
Oops! My enthusiasm jumped to far. Agreed I should NOT have used a bridge rectifier especially as my set up does have a common ground connection for my test equipment. Fortunately in this set up it only loads the generator outputs rather badly without any lasting effect. Real world AC it would be rather different. The better way to show things would be a small low voltage mains transformer, say 6vac, and a switched selection for each category of rectification using a 10K load.
alsetalokin4017:
Well, if one is trying to demonstrate such things for students, or even for a technical YT audience... perhaps using a toy oscilloscope and an unknown FG isn't the best way to go. On the other hand if one is trying to demonstrate the features and capabilities of the toy scope, perhaps characterizing a FWB, or even two diodes, isn't the best way to do it.
Careful study of the scopeshot I posted above will reveal many things, both about the rectification function of the diodes and about using an oscilloscope to display the phenomena.
By the way the scopeshot was obtained using a packaged FWB and an analog FG.
IanMacdonald:
If your sig gen output is capacitor coupled, placing a diode in series will cause the series capacitor to become negatively charged until no more current flows. Which could explain your lack of a waveform.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version