Hello all. I am using a Raspberry Pi microcontroller to drive a mosfet switched solenoid valve circuit which will deliver a sucrose solution to a lab rat. While the rat is working, I am monitoring its neural activity. The problem I have is that the recording equipment is picking up the voltage spike from the solenoid switching, but not exactly consistently. The circuit I am using is below:
V1 = RPi GPIO, 3.3 V pulse
V2 = 12 V battery
R1 = 100k
R2 = 68
D1 = 1N4001, standard diode
MOSFET = IRLB8721PbF
Solenoid = 12V DC valve, 3.6 W power rating, 50 ohm DC resistance, <300 mA rated current
What I'm recording is something like this:
where there is no spike for several trials, then the spike appears and has a variable amplitude.
All the grounds in this circuit, including the power supply to the pre-amp in the neural recording rig are tied together to earth ground.
If anybody could offer insight to help me understand this problem or to improve this circuit, I would be eternally grateful. Thanks for your time.
V1 = RPi GPIO, 3.3 V pulse
V2 = 12 V battery
R1 = 100k
R2 = 68
D1 = 1N4001, standard diode
MOSFET = IRLB8721PbF
Solenoid = 12V DC valve, 3.6 W power rating, 50 ohm DC resistance, <300 mA rated current
What I'm recording is something like this:
where there is no spike for several trials, then the spike appears and has a variable amplitude.
All the grounds in this circuit, including the power supply to the pre-amp in the neural recording rig are tied together to earth ground.
If anybody could offer insight to help me understand this problem or to improve this circuit, I would be eternally grateful. Thanks for your time.
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