Voltage regulater or capacitance multiplier?

[reubenm]

Hi,
      i'd like to know,
      is the following circuit a voltage regulator, or is it a capacitance multiplier? i saw it in the Neumann Handheld microphone schematic. secondly,i'd like to ask... does a voltage regulator remove AC ripple from mains? any help are greatly appreciated tx, reuben

 

[reubenm]

Neumann Handheld microphone schematic-from Gyraf's site:

 

[reubenm]

i think it's a voltage regulator (correct me if i'm wrong) ,but i cannot make out the reason for the capacitor in the bottom. on the other hand it may be a capacitance multiplier? any help is appreciated, thanks.

 

[JohnRoberts]

Hi,
      i'd like to know,
      is the following circuit a voltage regulator, or is it a capacitance multiplier? i saw it in the Neumann Handheld microphone schematic. secondly,i'd like to ask... does a voltage regulator remove AC ripple from mains? any help are greatly appreciated tx, reuben

This is a C multiplier smoothing filter with a programmed in 2 diode drop... 47K across 1 Vbe draws a constant current that forces a 2x Vbe drop across 100k, + base current times 100k. The extra drop insures it will clean up ripple voltage

JR

 

[reubenm]

so john roberts...i'm your fan,thanks for that explanation..i got it.

 

[reubenm]

does f=1/(2*pie*R*C) apply to the output?... say the collector resistor 100k as R and the cap as C? seemed like it in experiments. tx

 

[reubenm]

This is a C multiplier smoothing filter with a programmed in 2 diode drop... 47K across 1 Vbe draws a constant current that forces a 2x Vbe drop across 100k, + base current times 100k. The extra drop insures it will clean up ripple voltage

JR

the voltage drop you mentioned, 2 Vbe + (Ib x 100k) ...if it is 1V drop in total ,and the ripple was 45V ripple,would this circuit still be adequate to clean ripple? tx

 

[JohnRoberts]

does f=1/(2*pie*R*C) apply to the output?... say the collector resistor 100k as R and the cap as C? seemed like it in experiments. tx

Not exactly because ripple waveform is not a simple sine wave.

JR

 

[JohnRoberts]

the voltage drop you mentioned, 2 Vbe + (Ib x 100k) ...if it is 1V drop in total ,and the ripple was 45V ripple,would this circuit still be adequate to clean ripple? tx

no..

Voltages on schemo are DC... so  42V DC on output, 44 V DC on input side, this is close to my estimate of 1.5V  In fact a diode drop of .66V would work out perfectly to 2V total.

AC ripple voltage on top of the 44V DC will only be a volt or so (?)  If the bottom or lowest part of the ripple voltage dips lower than the base voltage the transistor saturates and stops being a super filter.

JR

 

[reubenm]

thanks alot JR, you've more than answered my query.tx