Hello,
I'm working on a project that involves the use of a digipot to control the current to the base of a transistor. Right now I just have an AD8402 14-port digipot, and I'm using it to blink an LED by switching the resistance from 0 to 10k every couple hundred milliseconds via SPI communication with an arduino UNO (the big box on the left in the circuit diagram attached below). I'm only using one of the two possible wipers on the digipot. For some reason, the digipot appears extremely sensitive to ambient capacitance (not sure if this is a real term), because the circuit is acting like a capacitance sensor. When I move my hand near it, or move it, it affects the function of the circuit. The LED will stop blinking, and instead slowly increase in brightness as I move my hand towards it.
Is there any way to prevent this? Ideally I want this to be a high-fidelity circuit that works as expected. Do I need to ensure all pins on the AD8402 are grounded or hooked up to something? Thanks so much, first time posting on this forum.
Also as a side note, it is necessary to use a digital potentiometer rather than an analog potentiometer for my project because I need to control resistance from an external input (eventually) wirelessly, and can't just adjust manually.
I'm working on a project that involves the use of a digipot to control the current to the base of a transistor. Right now I just have an AD8402 14-port digipot, and I'm using it to blink an LED by switching the resistance from 0 to 10k every couple hundred milliseconds via SPI communication with an arduino UNO (the big box on the left in the circuit diagram attached below). I'm only using one of the two possible wipers on the digipot. For some reason, the digipot appears extremely sensitive to ambient capacitance (not sure if this is a real term), because the circuit is acting like a capacitance sensor. When I move my hand near it, or move it, it affects the function of the circuit. The LED will stop blinking, and instead slowly increase in brightness as I move my hand towards it.
Is there any way to prevent this? Ideally I want this to be a high-fidelity circuit that works as expected. Do I need to ensure all pins on the AD8402 are grounded or hooked up to something? Thanks so much, first time posting on this forum.
Also as a side note, it is necessary to use a digital potentiometer rather than an analog potentiometer for my project because I need to control resistance from an external input (eventually) wirelessly, and can't just adjust manually.