All Questions
Tagged with 12v transistors
17
questions
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Interface higher voltage signal to 5 V pull down input signal circuit using discrete hobby components
I have a microcontroller, TTL logic that expects its input to be connected to the ground via a brake lever to tell the microcontroller that the brake has been applied. I believe it uses an internal ...
- 286
2
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0
answers
167
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2N2222 NPN Transistor, no current flowing through collector
I have a 2N2222 NPN Transistor wired up in the most basic common emitter setting (emitter grounded, base hooked up with a 1k resistor to 5V, collector connected to load and load connected to +12V). ...
- 21
0
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2
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141
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How does one use a transistor connected in either series or parallel with the load in a linear regulated power supply?
Let's say using a transformer and a rectifier to bring the voltage supply to roughly 18 DC (little voltage ripple which solved by using polarised capacitors) and I use a LM7812 regulator to bring down ...
0
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1
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672
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Switch 12V with 3V control circuit
Edit:
I did a dumb-dumb. I got the emitter and collector mixed up on both transistors. Now it works.
What I'm trying to accomplish:
I'm planning to run a ESP8266 microcontroller in my car. The ESP ...
0
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1
answer
1k
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Replacing BD139 for TIP122 - Cooler speed control circuit
I'm using a cooler (=fan) to conduct heated air through a hose to a closed chamber using an Arduino UNO PWM . A PID system controls the current across an array of resistors to target the setpoint ...
- 35
-1
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1
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98
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Reversing the input of a transistor
I want to detect if a 12V DC line has power or not. I want the transistor to work like this: If pin 2 has 5-12V, pin 1 and 3 should be disconnected and should stop the flow of 5V 2A across pin 1 and 3....
- 141
0
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225
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Get signal from apartment intercom to know when someone ring
In my apartment I have an old intercom to know when someone is at the entrance of the building and to unlock the door. I waned to connect it to an esp8266 to let me know remotely if someone ring and ...
- 103
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292
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2n2222 with 12v 8mA [closed]
I have a circuit running on 12v 8mA and I want to get a signal to a GPIO of an esp8266 when current is running. So for that I tried to use a 2N2222 transistor with vcc of the circuit going to the base ...
- 103
1
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2
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8k
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Can i switch npn transistor using 12v
I want to switch on 5V when switch is connected to 12V. I have been using relay to do this, but I am wondering if I can use NPN transistor or something similar that is cheaper and smaller than a relay....
1
vote
1
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248
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Transistor switch - extra resistor required?
I am new to electronics and this forum, and am in the process of building a Raspberry Pi based homebrew controller.
Following the article in the eLinux wiki, here is the relevant part of my circuit:
...
- 13
0
votes
2
answers
4k
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Transistor use - Basic fan speed controller
Someone mentioned to me that they wanted to replace a fan switch with a potentiometer to adjust the fan speed. This seemed a reasonable request, and being eager to learn, I drew up a schematic using a ...
- 1,089
0
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2
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1k
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12 volt switched by 5 volt
I have an issue with 12 volt DC LEDs installed on a 5 volt DC circuit. Switching must be performed as close to instantaneous as possible.
So I searched around but nothing would do what I need. I ...
- 1
2
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2
answers
2k
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Basic 12V Step-Start Circuit For Automotive Fans: Troubleshooting
To keep this short and sweet, I wanted to make a circuit/controller to decrease the inrush current on a large powerful fan for my race car. I ideally just wanted something that wouldn't let the amps ...
4
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2
answers
12k
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Generating 12V PWM from 5V PWM
I am generating a 5V PWM signal from my MCU (an Atmel ATMEGA1284P). I need to convert this to a 12V PWM signal. For this I designed the circuit below, something very similar to a Sziklai pair, but ...
- 247
0
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1
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425
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Transistor shortcut
i would like to fade an led strip using pwm with a n mosfet led that is commanded by a two way switch ( relay and sw1 ) like this:
simulate this circuit – Schematic created using CircuitLab
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