Voltage divider question

[dwinstonwood]

Hey all, I was looking at some schematics and I can't get my head around this. I'm sure it's really simple.

I know that the resistors in diagram "A" form a voltage divider.

I know that the capacitor and the resistor connected to ground in diagram "B" form a high pass filter. But, do the resistors in diagram "B" also form a voltage divider even though the resistor connected to ground comes first?

I assume the capacitor and the resistor connected to ground in diagram "A" also form a high pass filter. So, are the two resistors in "A" acting in parallel, so that they act like one 235K resistor to ground?

Is there anything else going here on that I'm missing?

Thanks!

[WimWalther]

In A, the signal exiting the cap is divided in half by the pair of 470K.

In B, the cap & first 470K form a voltage divider, the ratio of which is determined by the impedance of the cap at a given signal frequency. The second 470K doesn't do anything other than increase the output impedance of the circuit by 470K at all (within reason) frequencies.

[shooter]

it's been 40years, wasn't going back for 'ol time sake 

[PRR]

Draw the whole circuit, the source and the load.

[dwinstonwood]

Thanks WimWalther.


Basically what I saw in "A" was a coupling cap and a voltage divider. In "B" I saw a coupling cap, a high pass filter, and a grid stopper.

Until now, I really never thought of a high pass filter as also being a "CR voltage divider." But, I guess if you are attenuating lower frequencies then there is an attenuation of certain signal voltages happening as well.

Thanks!

[dwinstonwood]

Draw the whole circuit, the source and the load.

Thanks PRR. Yep, I can see now that I need to include those too, in order to get the whole picture. More thinking is required! Gotta hit the hay now (alarm goes off at 5am weekdays).

[WimWalther]

Now.. you can also view A as a 2-pole voltage divider, with a tap on the second pole. The cap & first 470k form a single element the impedance of which is the sum of the cap's reactive value at the signal frequency  summed with 470K.

This then forms a divider with the 2nd 470k. The only thing you know for sure about the output signal is that it will never be greater than (just under) 1/2 of the input level.

As frequency rises, the ratio approaches 1/2 as an asymptote. As frequency falls, so does the output level, again asymptotically.

[joesatch]

which gives better tone a 68k/68k voltage divider or a 470k/470k ?

[WimWalther]

which gives better tone a 68k/68k voltage divider or a 470k/470k ?

Folks here will need more information to answer that question. In short, you can't select a load impedance without first characterizing the driving impedance.

[HotBluePlates]

which gives better tone a 68k/68k voltage divider or a 470k/470k ?

Sometimes.

If my answer seems incomplete, it's because the question is incomplete.  You need to specify the things PRR mentioned here.

[tubeswell]

which gives better tone a 68k/68k voltage divider or a 470k/470k ?

:-)

[JPK]

This is a good read. Mostly about resistor types but he does get into how values affect noise. Only mentions tone once. Noise is not good tone. 


https://www.aikenamps.com/index.php/resistor-types-does-it-matter#:~:text=The%20most%20significant%20contributor%20to,that%20of%201%2F2W%20resistors.
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