My main goal is to produce sound via the atmega 328p chip (using PWM). I am building up my circuits step by step and trying to understand what is going on.
I am now at the stage where I have added an OPAMP as buffer to protect my Arduino output pin. The issue is that one of my two opamps is producing an output I don't understand.
* description of schematic *
You can see the schematic attached to this post (schematic.jpg). The status is that my arduino is powered by my PC (via USB). The arduino produces a Saw-tooth wave using my program. The pwm output is passed through 2 RC-filters to smooth the signal. At this stage the output is between 0v and 5v. The 2k resistor is added as a pull-up resistor and the resulting signal is between 2.5v and 5v (I wanted to be sure I was within operating range for the OPAMPs). The output is fed into an opamp with negative feedback (unit gain) and output is measured with my new oscilloscope (which most likely can make a screenshot - but I don't know how yet... well...). The OPAMP is powered by a 9V battery having common ground with the arduino.
Using JRC062d (taken from an old multimeter) as opamp seems to work as expected. It produces the same output as its input (see attachedment: JRC062d_works.jpg).
The other opamp: TS922 seems to have an issue. It does not produce the same output as its input. The output seems to have slew rate? = 2V/500us = 4 mV/us .. and datasheet sais MIN. 700mV/us... I am confused.
any suggestions?
I am now at the stage where I have added an OPAMP as buffer to protect my Arduino output pin. The issue is that one of my two opamps is producing an output I don't understand.
* description of schematic *
You can see the schematic attached to this post (schematic.jpg). The status is that my arduino is powered by my PC (via USB). The arduino produces a Saw-tooth wave using my program. The pwm output is passed through 2 RC-filters to smooth the signal. At this stage the output is between 0v and 5v. The 2k resistor is added as a pull-up resistor and the resulting signal is between 2.5v and 5v (I wanted to be sure I was within operating range for the OPAMPs). The output is fed into an opamp with negative feedback (unit gain) and output is measured with my new oscilloscope (which most likely can make a screenshot - but I don't know how yet... well...). The OPAMP is powered by a 9V battery having common ground with the arduino.
Using JRC062d (taken from an old multimeter) as opamp seems to work as expected. It produces the same output as its input (see attachedment: JRC062d_works.jpg).
The other opamp: TS922 seems to have an issue. It does not produce the same output as its input. The output seems to have slew rate? = 2V/500us = 4 mV/us .. and datasheet sais MIN. 700mV/us... I am confused.
any suggestions?
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