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The same thing happends. :confused:
Here in Europe it is the same.
10x or 1x probe makes no difference. Anyway, the compensation is spot on.
Again, looking at the high voltage measured, this is a bit of concern to me. Could this be a fault in the signal generator?
If I attach the scope...
Thank you. I'll try when I get home. But that sound strange... look at the voltages measured: 90 V peak! I've seen circuits picking up noise, but 90 V peak looks like a powerful noise! One of my DMM measures a high DC voltage too (around 50 V), so it is not something related to my scope reading.
Hello everyone.
I just realized something strange playing around with a simple voltage doubler.
The doubler works fine. I use a signal generator as input. A simple DMM measures the DC output.
The thing is: just cliping a scope's probe clip to the circuit can make it go crazy.
Attached, two...
That's the point I missed. Thank you.
And that one too. I understand now.
Right. But I do need relative measurements, and that require flat frequency response. If some frequencies were attenuated, how could I know that some relevant frequency is really higher than some other, or just seems...
Doesn't the 10x probe have to be terminated too?
Even if it is probing a 50 ohm resistor, the signal travels through the 10x probe cable (from the tip to the BNC connector on the scope).
If the 10x probe cable is 1 meter, and the signal is 60 MHz (5 m wavelength), wouldn't there be trouble?
That leads me back to the initial question: What is the proper way to do this, considering the reflections?
Another point is, If using an spectrum analyzer, a 50 ohm is imperative. Would it be a correct tool?
What about reflections?
Simple test: if I probe a 50 ohm sig gen output directly using a 10x probe, a point in frequency is reach when the reading is not accurate. If using a 50 ohm termination right at the probe tip, it works. So does using a coax and 50 ohm at the scope's input.
Well, I can...
Well, I'm using a test signal of 0.1 V, which is high enough, and using the FFT of the scope (140 kpoints) I can easily follow the signal level.
I compared to a cheap spectrum analyzer (using the exact same coax), and the levels read are close enough.
The problem I see with 50 ohm and the scope...
Probe the signal (level) going through a radio receiver (from input to audio stages), for instance.
For some sensible things such as analog oscillator output, I know I have to use an active probe or there'll be a frequency shift due to parasitic capacitance.
Right now I'm using DDSs as...
Hi everyone.
- A 10x probe is meant to isolate the circuit from the scope as much as posible (using pasive probes), but the problem is the impedance mismatch (a 50 ohm termination at the scope input is not enough).
- A 1x probe is not 50 ohm, and has low bandwitdh.
- so it seems that a simple...
Hi there.
I found a website that uses Miller's Theorem to analyze a simple collector biased transistor (voltage shunt feedback). There's something about the ouput Z that I don't understand.
https://wiki.analog.com/university/courses/electronics/text/chapter-9#example_972_using_miller_s_theorem...
Yes.
You were absolutely right in that the inductor widens the capacitor tunning range a little bit.
It doesn't seem so. At least not in this particular circuit. But I've seen other topologies where that seems to be the case.
Yes. "Practical Oscillator Handbook" is good one too, not only crystal related.
With a 50 pF variable cap I can slow down the frequency a couple of kHz.
Strange... I thought that adding series capacitor increases crystal's resonance frequency.
It is part of an amateur CW transmitter.
Yes, it makes sense.
Any idea why that inductor in series with the xtal?
It must be some kind of frequency compensation, but I've seen many many circuits like this, with the variable capacitor but no inductor...
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