otherwise it wouldn't be measured!) so there should be no current flow at all. You would still want the pull-down resistor from the base to ground, but when a pin is in INPUT mode it has a very high impedence and won't have any bias towards ground or Vcc (well, tiny tiny tiny amounts.
When you want to guarantee that a transistor has no current flowing from a pin into its base, place the pin in INPUT mode using a call to pinMode(.) and only set it as an OUTPUT using the same function when you want to turn the transistor on. Here's a more advanced way to go about it and I'll bet it would work with the TIP120 you have: It is widely used by engineers and hobbyists for general-purpose amplification and low-speed switching. That should be enough to turn the transistor completely off as long as there is no current coming from the pin. TIP120 is a popular NPN Power Darlington transistor. You bet! I'd still try the 1K and a ~27K or something between the base and ground. This is my first time working with transistors, and I'm stumped. The I2C sensor ( SHT40 ) works fine ( I can read from it without issues ).The 5v connection comes from the ESP's 5v pin ( which is connected directly to a battery, that can supply enough current. This only happens when there's an I2C device inserted into the header. When driving the pin HIGH, the transistor turns on ( as expected ), but when I drive it LOW, the transistor reads ~1v.
Tip120 transistor arduino code#
The esp I'm using is a TTGO T7 Mini32, and the code I'm using is here. Features High DC Current Gain hFE 2500 (Typ) IC 4.0 Adc CollectorEmitter Sustaining Voltage 100 mAdc VCEO(sus) 60 Vdc (Min) TIP120, TIP125 80 Vdc (Min) TIP121, TIP126 100 Vdc (Min) TIP122, TIP127 Low CollectorEmitter Saturation Voltage VCE(sat) 2.0 Vdc (Max) IC 3.0 Adc 4.0 Vdc (Max) IC 5. This original Arduino Due has the size of Mega with a higher processing power than. could R1 be the issue here? I did try several diffrent values) Buy TIP120 NPN Transistor TIP 120 60V 8A in Sungai Buloh,Malaysia. I have everything connected as depicted below ( my DMM is broken, so I don't have a way of checking resistance. Hey all! I'm trying to build a weather station, and to save power, I want to have a transistor to turn off the power to the sensors, RTC, and transiever when the esp32 is in deepsleep.
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