#1213 Filter Frequency Response with Oscilloscope and Generator

Episode 1213
How to do a filter response sweep. I use my HP33120A in sweep mode which outputs a sweep signal and start of sweep sync pulse. the sync pulse is used as an external trigger signal on the oscilloscope

[sbelectronicaindustrial]

A little less than a month ago I subscribed to your channel, and all your videos are very captivating, very good information and very professional explanation.

[sbelectronicaindustrial]

Hello, the video is very good, like all the other videos on your channel, the information you provide is very valuable and important... Greetings from Buenos Aires....

[adrianvonino]

Wow, i never would have thought about such a trick. Thanks for sharing

[brainndamage]

It's like a simulator, but IRL! I often use LTspice to work out designs initially, it saves a lot of time.

[markmaister]

Best video I found about this matter, thanks

[nowt]

I did a similar thing to make a tape for setting up the resonance of the heads on early vhs recorders. I made a circuit that generated a ramp triggered by the video field sync and fed the output of that to the vcrs fm modulator and recorded it. I fed the sync to the vcrs servo circuit as well so it had something to lock to. You can see the frequency response of the heads and preamp on the scope and you set it up to peak at 5mhz. I had to put a marker on the tape so I could tell where 5mhz was. I used a comparator for that to briefly pull down the input to the record amplifier when the ramp reached the voltage that corresponded to 5mhz output from the modulator.

[aduedc]

You could use white noise generator as your source and Spectrum Analyzer for monitoring the output, I think your oscilloscope should have FFT function or Spectrum Analyzer.

[ketv]

I came late to the party, so obciously I've not seen your whole back catalog. Have you done episodes on log amps? An envelope detector and log amp is what you really need there - in which case you've built a DIY scalar network analyzer.

(The next step would be to have I and Q signals available for vector analysis, but that's harder, of course.)

(And yes, I know you have a VNA and I know why you're not using it here.)

[jp]

Don't you have an external trigger input on the scope? I thought that was where you input sync pulses so you don't burn a channel on the scope. Especially if you only have a 2 channel scope. Thanx for showing how to set this up. Most channels show the signal but not how to set up the gear. I would love to see how to setup scope/generator to measure signals when aligning FM tuners.

[amins]

I dont fined any data of Voltcraft Dscope 707 Scopemeter, you help me?

[pilobond]

My cheap function generator doesn't have the proper "sync" output. But it can have channel 1 frequency modulate on channel 2. So what I do is I put on a sawtooth on Ch2, let's say 0V to 5V. Then I frequency modulate on this to Ch 1 (enter proper parameters to set frequency spread corresponding to 0v-5V.) Then I trigger on Ch2, while looking at Ch1.

[benrasmussen]

Thank you, very educational. Would you have an idea about how to get a pattern that is 4 waves that are syncronized , that are 90 degrees apart could be generated?

[marcorademan]

You have a nice scope, so I'm guessing FFT with persistance mode is an option? This might require you to slow down the sweep though

[tonyfremont]

Setting a trigger hold off should do what you want, as far as not retriggering after the first sweep.

[chopperlw]

What a great visualization. I've never seen that shown on a scope before. Must be nice to have a sweep generator :)

[davidbeauchesne]

How about the Bode plot built in to your Rigol scope?

[jeremycyclist]

You could add a peak detector in front of the oscilloscope input, you will see only the envelope. I suggest to use germanium diode(s).

[tsusec]

For this i used EXT trigger input on my 2CH Rigol. Other than that, all the same methods as yours were used.

As far as i can remember MSO 5k can bode plot this for you.

[kunalblack]

I want to learn radio electronics from the scratch ..what do i need ..?

[AlessandroAllegretti]

Very interesting and inspiring! Thank you!
What are your intentions? 😊