VLF MD with digital signal processing : Bee-Buzz 1

[pito]

If you want an exact description of how the circuit works then do a search for "Marshall Leach moving coil preamplifier". Richard Lee adapted the circuit slightly but there should be a link somewhere to Leach's original circuit description...

I don't need description just modification of original is wrong

[pito]

The power supply vee and vpp are unreferenced to ground.

Parallel to battery there are 2 capacitors 100uF in series = 50uF for 10kHz that will be less than 1 ohm shorting AC signal

[Olly]

If you want an exact description of how the circuit works then do a search for "Marshall Leach moving coil preamplifier". Richard Lee adapted the circuit slightly but there should be a link somewhere to Leach's original circuit description...

[pito]

Source: https://www.hifisonix.com/articles/r...e-mc-head-amp/
head amp = audio amp 20Hz to 20KHz = That's why they are using large capacitors

[moodz]

...but you don't need years for a powered version.

[moodz]

The power supply vee and vpp are unreferenced to ground.

[Olly]

Those are two different vesions. The first uses a battery to float the biasing supply and the second is a powered version where a more standard power supply is used. According to the originator of the design the floating battery version has superior noise performance. He says build the first then use it while you try for years to get a powered version to work as well.

It's a very, very clever and simple bit of circuitry...

[pito]

No, it is for defining the collector current.

those resistors do 2 jobs the second one is AC separation from power lines, in your drawing they are missing

this may work,
100uF for 10 kHz ? = bad idea, should be in nF

[Aziz]

original = prevented from short circuit for AC

No, it is for defining the collector current.

[Aziz]

Look at the circuit simulation. Make the sim and inspect all the current flows. It isn't a short circuit nor is a "black hole".
Aziz

[pito]

original = prevented from short circuit for AC

[Aziz]

Hi all,

ok, it's really time to make the circuit simulation by yourself and investigate the pre-amp. Below is a working spice file for download. But be careful and don't fall into the current "black hole".

Below picture shows my first real working prototype (above) and the next in preparation with the op-amp driver (below).



Cheers,
Aziz

[pito]

[Aziz]

Aziz,
Maybe you go far from serous logic - to amplify signals via power supplies lines - or I'm not right? Don't trust in every cases on software simulation.

This is not my idea. It's been used for ages. And my first prototype is working too. But I need the improved version.

[Detectorist#1]

Aziz,
Maybe you go far from serous logic - to amplify signals via power supplies lines - or I'm not right? Don't trust in every cases on software simulation.