Currently, I am using the above BJT circuit to find out the DC characteristic and I need to measure the DC voltage at the Vo. As per the instruction of the lab manual, I am told to adjust the variable resistor and keep the Vo at 1/2 Vcc value which is 10V. However, the problem occurs when I added in my own Arduino Micro oscilloscope. You can find the Arduino Code, the processing oscilloscope code and the connection here^ (Arduino Micro Oscilloscope: https://www.instructables.com/Arduino-Oscilloscope/#discuss)
Since I only need the 20V range, I removed the switches connecting 5V and AREF and just short it. I also removed the other switches from D3 and D4 as those are for voltage scaling which I don't need.
The problem is once I connected the BJT circuit to my Arduino Oscilloscope, the output voltage drops to 1.6V (Measured from an oscilloscope) and my Arduino Micro oscilloscope is also having a measurement of 1.6V. What is the reason for the drop of voltage from 10V to 1.6V?
I tried troubleshooting by connecting the Arduino oscilloscope to a 10V power supply, the waveform is maintained at 10V so I don't know where the problem occurs.
It sounds like there's a problem with the oscilloscope circuit. Can we have the link? Does it work otherwise? Can it measure 5V and 0V? Ro, maybe the 20V? (But "be careful"!)
The Arduino can be damaged by voltages greater than 5V or by negative voltages so there should be a voltage divider and a protection circuit on the input if you're connecting it to a higher-voltage (or negative voltage) circuit.
I tried to connect just the power supply of 20V and 10V to the Arduino Oscilloscope and I am able to see the DC waveform of 20V and 10V respectively. But once I connect the Arduino Oscilloscope to my BJT circuit, the output voltage drop to 1.6V.
You should explain what you really want to get. The circuit is sensitive to AC only, not DC.
If you want a usable scope then either buy one or add a high impedance amplifier to the Arduino scope. As long as you can't explain the behaviour of the circuit you can not sincerely measure any signal.
The 4k input impedance of the 20V range is ridiculous for any meter. Good meters should have at least 20k/V, i.e. 400k for 20V.
I will try the 400kohm for the voltage divider. Thanks.
For the BJT circuit, firstly, I am finding the DC characteristics of the BJT. At the start, I only switch on the DC power supply at set it at 20V and leave the AC generator off. For the output voltage, I need it to be at 1/2 Vcc which is 10V and from there I can measure the variable resistor ohm and the collector current. Therefore, I needed the output voltage to be 10V and from the normal oscilloscope I was able to measure it and found 10V. However, when I used the arduino oscilloscope, I only found it to be 1.6V.
