Thank dear friends,
I got similar simulation result for oscillator(rectangular pulse with about 1kHz frequency) but the output result is different from yours, it contains a DC part around 800mV and a non-desired ~250mVp-p ripple. That's because you disregard the cap of last stage
Power supply voltage is +5V but it seems in your simulation it is +10V.
In reality when I short circuit the probe, I get about 3V and with 10k+ or open loop, I get 0V.
In simulation I used 10k for unknown impedance.
The whole device contains another board with 2 7-segments and some LEDs.
It connected to the analog board with 10 wires(the connection is recognizable at the bottom of attached PCB image).
The analog board has 3 LM324 and the display board has two CA3161 BCD to 7-seg driver.
So I think the OpAmps of analog board converts the unknown impedance to BCD.
The probe is simple as wire.
I don't have a dental maquette so I connect the probe to a trimmer.
The device is built to help dentist to determine the apical area of tooth.
Ok,
Replacing the 1uF with 47uF in simulation has a very nice effect on removing ripples, but in action it doesn't have so much effect.
So I want to use an active LPF to remove undesired ripple and noise.
**broken link removed**
With R1=47kΩ, R2=100kΩ, and C2=100nF the cut-off frequency is 1/{(2π)(R2)(C1)}≈0.16Hz so I think it'll remove noise and ripples very well.
Am I right?