# Tagged Questions

68 views

### Difference between op-amp and MOSFET? [on hold]

1.S An operational amplifier (op-amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. 2.S A transistor is a ...
87 views

### Will this motor controller take more motors?

If I was to connect two motors in parallel instead of just the one motor it currently has on each H-Bridge,, would the transistors on the motor controller blow? I have this motor controller - here is ...
195 views

### Need help calculating resistance for transistor base

I have 3 12VDC/40A automotive relays (datasheet) that I want to use with my Arduino. Based on the tutorial I am following (link) I need transistor, resistor, and diode. I am not an electrical engineer ...
260 views

### How to calculate current through an H-Bridge

Given the below H-Bridge, how do you calculate the current through the conduction paths? This particular IC, the L298, has a per-bridge limit of 2A - so I know the upper limit. If I were to place a ...
165 views

### Transistor not giving enough current

I am using a TIP120 Transistor with pwm from my Arduino to fade an led strip. The RGB led strip requires 12 volts and 1.6 amps of current. I bought a 12 V / 2.5 Amp power supply from Radio Shack and ...
186 views

### 2N2222 Base Current Maximum Tolerance [closed]

I have a 2N2222 transistor that I plan to use with an Arduino Uno. My question is how much current can this transistor handle at it's base?
292 views

### How to sense the zero crossing of current?

I am trying to sense the power factor angle using microcontroller. Now the mechanism that I have thought it that Measure the zero crossing of voltage When the voltage zero is sensed, start the ...
472 views

### Using a transistor to add to max current output from a opamp?

I thought I understood transistors but now I'm confused again. I have a basic opamp circuit to amplify the input of a electret microphone. The output of the opamp will vary within 1-4V. Now I want ...
182 views

### Is this switch circuit correct?

This is a follow-up question to How high is "high impedance" on this chip (CD74HC125E) I finally decided to use a pn2222 transistor to act as a switch that activates the transmitter. The ...
160 views

### transistor loop to limit the current

I am trying to implement the DALI TX/RX circuit below. The description says: The other transistor (T2) is controlled by the current flowing through the resistor (R1). If a DALI slave unit is ...
209 views

### arduino pulse to transistor power maximum

Hello I want to get a confirmation that what I am doing is not going to fry my Arduino Mega. The sketch I am using to send a pulse out on pin 8 to a 2n3055 that is switching 12 volts is this: ...
433 views

### Transistor current mirror circuit

simulate this circuit – Schematic created using CircuitLab Can somebody please explain me how a transistor mirror circuit works and how can it be used as over current detector? I badly ...
187 views

### Transistor varies with Temperature

My questions pertains to the $\beta$ value of a transistor. On page 162 of this book, it says that $\beta$ increases as temperature of the transistor increases. But it doesn't explain why. Can ...
613 views

### Problems with Transistor TIP122

I was testing some things on my protoboard to learn a little about transistors. I made this: The batteries are two AA 1.5V in series. The resistor is a 1Kohm. The transistor in a TIP122 npn ...
417 views

### Purpose of these two transistors

Hi does anybody know what's the purpose of the Q1 and Q2 transistors, sounds to me like they are constant current sources. Am I wrong? Could somebody explain me the purpose of those Q1 and Q2 ...
211 views

### Current flow priorities in PSU / PSU review

Being an electronics hobbyist, I'm having quite a challenge to design a PSU, which must run both on batteries (during the night time) as well as on Solar energy (daytime). The device is intend to run ...
2k views

### Arduino/Atmega with TIP120/121/122 transistors: base current question

I am learning about transistors, and can't seem to find the answer to a few questions which are stumping me. I will be referring to the TIP120/121/122 Darlington Transistor. As I understand ...
409 views

### safety margin in transistor base current

In this answer poster calculates a safety factor of 10 for the minimum base current in a transistor used as a switch. Seems like a lot to me, and for higher collector currents this may mean that a ...
414 views

### BJT in Active/Linear mode — How can it still conduct current?

So I've read quite a few books on how BJT's work and all of them seem to gloss over how a BJT in the linear mode with the base/emitter junction forward biased and ...
223 views

### Understanding a transistor configuration

I started watching this video series on a DIY lab power supply by Dave @ EEVBlog. On his video he's analyzing mostly simple constant current circuit. However, at the top of the circuit there's two ...
2k views

### Transistor current limiter, microcontroller controlled?

I've come across a few transistor current limiter schematics, similar to this one: However, I am not entirely sure how I could implement microcontroller functionality to control this. I think ...
1k views

### How does transistor amplify current? [duplicate]

Possible Duplicate: I don't care how a transistor works, how do I get one to work? Basic questions about transistor amplification I have heard transistors are used in many electronic ...
450 views

### Transistor in saturation mode?

I was wondering why do we so often want out transistor to work in saturation mode? Ie. For a MOS Current Steering Circuit we want our transistors to operate in the saturation region....