11 votes

Find out value of pF capacitors

We regularly measure C(V) curves of some components such as transistors for validation purposes, where the target resolution is 0.1 pF or better. simulate this circuit – Schematic created using ...
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7 votes
Accepted

For below circuit, the simulation result is not matching with theoretical prediction

At \$ t=0^- \$ right before the switch opens, we're at DC steady state, so inductors are shorts and caps are open. The top capacitor has charged to voltage V, which means no current flows in the ...
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3 votes

Find out value of pF capacitors

Adding a bit more to Tobalt's answer, the following LTspice simulation shows what to expect. This type of meter is resistant to parasitic capacitance since the measuring node is at virtual ground. You ...
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3 votes

Difference between application of series and parallel (grounded) capacitor

As you correctly surmise, C1 and C2 are there to block DC on the input and output sides respectively. L2 and L3 form the "top halves" of voltage dividers, where the "bottom halves" ...
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3 votes

Difference between application of series and parallel (grounded) capacitor

So what you ask must be thought with the context that it is an RF device, such as RF amplifier. Yes, the capacitor in series is used to block DC and pass RF only. This lets the chip input to bias ...
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3 votes

For below circuit, the simulation result is not matching with theoretical prediction

The right-hand C has no charge at t=0 (L is short circuiting it at t<0), therefore this C looks like a short circuit at t=0. The upper C is charged to V, with + on its left-hand plate. This is the ...
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  • 7,274
3 votes

For below circuit, the simulation result is not matching with theoretical prediction

That's not the correct answer. I won't spoil it for you, but your approach with shorted inductances and opened capacitors is the right way to go. Then your LTspice approach is not correct, either. ...
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2 votes

Current surge protection for relay contacts when closing

I'll show you a naive MOSFET based current limiter, but it may be more of a liability than a solution, depending on how big those capacitors are. simulate this circuit – Schematic created using ...
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  • 7,843
2 votes

Find out value of pF capacitors

Just for fun, I tried doing this with a NanoVNA (a very inexpensive toy) connected to a short piece of coaxial cable. With the coax open, adjust the marker to the first half-wave resonance, where it's ...
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  • 1,601
2 votes

LC circuit with back to back diodes

Even a "simple" D+C circuit requires the LambertW function in order to determine its analytical formula (see jonk's answer, for example), but here you also have an oscillatory waveform. This ...
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2 votes
Accepted

Capacitor keeps exploding on nixie HV power supply

From MC34063 datasheet the 680pF cap on pin CT sets the frequency to something like 45kHz. It's not very accurate but let's go with that. A 45kHz period lasts ~22µs. With 12V input and 160V output, ...
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1 vote

Find out value of pF capacitors

This circuit can also be useful. It can be adapted for a lower scale ... calibration is needed. Or add a "doubled" circuit with the 2 diodes with the resistor of the same value for "...
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1 vote

Reset on lockup, by discrete analog components

You are describing a kind of watchdog timer. We have that function built into microcontrollers and discrete chips which perform that function autonomously. Generally they just pulse a reset input (or ...
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1 vote
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Inductor and Capacitor 3-digit exponent value codes: is there a standard?

I think there is at least a common sense for the base unit of a component. For capacitors it is pF, so 102 = 100 pF, 224 = 220 nF, 106 = 10 uF. If the component value needs digits below the base unit, ...
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