I am building a diode detector circuit in order to detect ASK signal with 125 KHz carrier frequency and 8 KHz data rate. However, I realized I would say a strange behaviour and discharging of capacitor. The setup is following: Function generator set to sine wave 3 Vp-p and f=125 KHz. Function generator is connected to anode (1N4001. From kathode goes C=1nF to ground as well as 330k ohm resistor. This value is for sure not correct but it was an experiment. Here is schematic:
The generator has 50 ohm input impedance. So, here is the waveform:
As you can see, capacitor is charging, but then suddenly discharges really fast until certain DC level at capacitor is reached. I would at least expect that charging stops as soon as capacitor is charged to the voltage that can't any more provide forward voltage for diode. In that moment it should start to discharge via resistor which should be pretty much slower than shown.
So, my question is why this happens and is there any feature of the diode that comes into game near the point of shutting off?
So, you were all right guys. I changed to 1n4148 and now it works fine, although I cant realize how can this voltage drop.