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Questions tagged [pnp]

A type of bipolar transistor comprised of p-type semiconductor in contact with n-type semiconductor which in turn is in contact with a p-type semiconductor -> thus PNP. The transistor has three terminals, the Emitter, Base and the Collector. Current injected into the base controls the flow of ...

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1answer
18 views

Voltage alarm with LT1017

With help of this site, I have redeveloped my voltage alarm circuit (see my previous question for the history). I started off with an 741 Opamp and it did not work as I wanted it to work (Thanks for ...
1
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1answer
80 views

What's the purpose of using PNP transistors on I2S bus?

What could be the reason of using these 3 PNP transistors on I2S bus (LRCK, BCK and DATA pins)? The DAC used in this schematic is PCM5102. I know for sure that this DAC would work without these ...
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0answers
39 views

Is this discrete mosfet driver ok?

I've come up with this mosfet driver, mostly inspired from other designs using push pull configuration. It consists of four transistors (1 pnp, 3 npn) + an optocoupler. Its intended operation is ...
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1answer
56 views

PNP Transistor switch circuit

I have been learning about transistors a lot lately. Following that I have managed to design a simple circuit that uses PNP transistor as a switch. Basically this is going to be a door alarm where if ...
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1answer
58 views

Is pulling current from Collector to Base allowed? (PNP transistor)

I am building a P-Mosfet gate driver and I have a question regarding the behavior of a PNP transistor connected in this way: This circuit might look pointless, but it's a good representation of a ...
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2answers
132 views

PNP load switching circuit that uses opposing PNP transistors

Background: This circuit uses two input signals to create a 0, 2.5, or 5V output signal that switches ON/OFF periodically to control for example an LED. I saw a transistor circuit example that had ...
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1answer
120 views

High voltage linear regulator (with pre-regulator)

I need to build a linear voltage regulator like this: The problem with the usual linear regulators (LM317, LM337, ..) is the limited voltages they can withstand. I have taken inspiration from a ...
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0answers
33 views

Switching HCSR04 with a PNP transistor and ESP8266

I want HCSR04 sensor to work for once in 10 minutes. So I thought I could use a transistor and reduce power consumption. But I could not use a NPN transistor because HCSR04 works even if the ground ...
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4answers
125 views

Toggle two LED status lights with two transistors

I have an input that is either floating, or grounded. The switch is fixed, it's either open or closed. Ie, I can't replace with a double throw. Here is the schematic / sim. If the switch is closed, ...
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1answer
55 views

Enable one or two of the same output via switch (minimalist schematic)

I'm making a PCB and my real estate is limited. I am using an AT89C2051 microcontroller, and it only has one serial transmit output. What I need is a way to set whether the output from the serial ...
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3answers
128 views

PNP instead of NPN in series voltage regulator

I have a question regarding PNP transistor, since I am not very familiar with it. What would be the difference in the circuit below, if we switched NPN to PNP? Right now the output voltage is equal ...
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2answers
277 views

How to calculate this two transistors Constant Current Source circuit?

I came across a constant current source calculator at Electronic Product website:enter link description here For example, for a 13.5V input, 300mA output, it comes out the following parameters: <...
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4answers
128 views

What kind of fan filter is this?

This schematic is part of a fan controller. simulate this circuit – Schematic created using CircuitLab FAN_POWER: 3.3 V (or 5 V for higher loads) PW_FAN: goes to the fan What kind of filter ...
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1answer
67 views

How to double the collector current of a BJT in LTSpice?

I am trying to model a multi-collector lateral PNP in LTSpice. The link here suggests to put 2 PNP transistors in parallel and split up the IS into two parts. http://pallen.ece.gatech.edu/Academic/...
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5answers
169 views

Transistor toggle by NPN and PNP - how is it build?

I want to toggle between 2 devices using one GPIO 3.3v pin and powering them with 5v. I thought about using an NPN and PNP transistor, tying up the base and collector/emitter to 5v power supply. If ...
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2answers
96 views

Am I right with select of base resistor?

simulate this circuit – Schematic created using CircuitLab I did add the NPN 2N3904 because I want to put on sleep the Arduino. So I need to put LOW the GPIO when goes in sleep. This is a ...
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1answer
167 views

Mixed NPN and PNP H-Bridge DC Motor Driver

I've briefly looked at including an H-Bridge circuit in one of my designs and I see that most (if not all) have N-Type transistors (either Darlington or MosFets). This however needs two separate ...
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2answers
771 views

Can someone explain this microcontroller ADC interface (for reading solar panel voltage)?

I am trying to understand the functionality of a circuit found in TIDA-00121 (you can download the design file from here) I assume that this has to do with the fact that the PV is not directly tied ...
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1answer
45 views

Need a bit of guidance in regards to this PNP transistor question

simulate this circuit – Schematic created using CircuitLab Hello! I'm currently stuck trying to answer this question. The question asks for me to find the resistance of R2 for R1 to be at 4V ...
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7answers
6k views

What's the purpose of these two diodes in this circuit?

What's to point of using these two diodes? Can't you just replace them with a resistor?
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1answer
211 views

How to connect a PNP inductive proximity sensor to a PC? [closed]

I have a PNP metal proximity sensor. I am using it to test a door lock mechanism. I need a way to connect this sensor to a PC and make a user interface to show me the signals and the values. I haven'...
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2answers
359 views

NPN or PNP transistor for Common Cathode Seven Segment Display LEDs?

I've read a bit about this but there seems to be much ambiguity. When using common cathode seven segment display LEDs would you use NPN or PNP? Or can you use either? Can someone please give a ...
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1answer
109 views

Why is my RGB LED strip passing current through the transistor?

I am following this schematic: http://www.electronoobs.com/eng_arduino_tut13_sch2.php It uses a BD140 PNP transistor. I checked the wiring was correct. Basically, the transistor boosts the current ...
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0answers
62 views

Transfer function of loop-back bias circuit for RF amplifier

I am trying to implement a current mirror as part of a bias circuit for a RF amplifier. I want to do a transfer function of the bias circuit since it creates a loop from the amplifier fet drain to ...
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3answers
390 views

Light up an LED with an NPN transistor in active low?

I have a circuit which is turned on at a logical zero. I would like to have a LED indicating this circuit is on, but I only have NPN transistors at this moment, which conduct when there's a logical ...
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4answers
282 views

How to safely measure VCEO or VCES of a transistor?

As an example, NPN Silicon Power Transistor TIP31 VCEO (Collector-Emitter Voltage) is rated at 40Vdc Maximum. I have many unknown transistors for which I would need to measure the VCEO. Many are power ...
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1answer
238 views

Inverting schmitt trigger with pnp transistors

I have a question regarding Schmitt Trigger. I am trying to design an inverting output (at UTP=Low, at LTP=High) Schmitt Trigger for an application. However, I need to use PNP transistors since the ...
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2answers
161 views

PNP transistor with audio signal output on collector is used to drive opto-isolator. How does it work?

I have tried assembling the circuit but it doesn't work. Now I need to understand how it works in order to debug it. The part that confuses me is: Channel 1 is a standard audio output from a ...
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3answers
398 views

Baker Clamp application for PNP Transistor

I have an issue related to Baker Clamp application for PNP Transistor. I know how to implement the Baker Clamp for NPN Transistor. However I do not know how to do it for PNP. So could anyone can ...
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2answers
143 views

12v PNP- switching with MCU

Hey I got a question about switching a 12V supply to a low power circuit with an MCU. My requiaments are: - switching has to be on the High side. - switch should stay "closed" when MCU is powered ...
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2answers
93 views

NPN-switching 4V with a 3.3V signal

I have a project where I need to switch the + side coming from the battery (single cell LiPo) to a consumer (ESP8266) with a 3.3V signal (common ground). I have loads of NPN and PNP-transistors here, ...
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2answers
61 views

Solenoid driver heating issue [closed]

This is regarding an automotive transmission control module(TCM) solenoid driver. The schematic diagram of the driver is very similar to the below image. Only difference is the TCM has the low side ...
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1answer
270 views

Using 2N2222 as level shifter for TIP127: simulation works, circuit does not [closed]

I'm building an H-bridge with complementary Darlingtons, TIP122 and TIP127, as they are cheap and the nearby shop has them (i know about the high power dissipation, it doesn't matter), and i found ...
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2answers
181 views

Problem testing a DC Motor Controller

I want to build a robotic arm for a project, but I got stuck while testing the motor driver on the breadboard. I have followed the instructions from this instructable: https://www.instructables.com/...
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3answers
107 views

Understanding constant current circuit

I've been learning about different constant current circuit designs and just recently stumbled upon this one. All I know is that the highlighted resistor is the load resistor and when varied, like a ...
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1answer
517 views

Water level indicator with PNP transistor

I wanted to create a circuit that Lit's up an LED when water level rises to a certain level. I have created the following schematics following the https://www.electronicshub.org/water-level-alarm-...
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2answers
138 views

How to understand the parameters of a transistor [closed]

I am trying to design a circuit using a transistor but I don't understand the parameters of the transistor written in the program. Does anyone know what is the meaning of the following symbols? I_s,...
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1answer
400 views

Ideal diode - PNP emitter-base breakdown voltage question (PMOSFET)

I'm hoping to create this ideal diode. With 12V. However, I feel like this would require the two PNP transistors to have an emitter-base breakdown voltage of 12V or more. Is this correct? (Such PNP ...
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4answers
3k views

Control 5 V load with transistor 3.3 V - Raspberry Pi

I'm currently having this project where I put a Raspberry Pi, batteries and a touch screen inside a book that can fit my pocket. This screen is constantly on, and I want to be able to turn it on and ...
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0answers
45 views

Identify two National semiconductor transistors 506 220-0075, 452 220-0076

I am trouble shooting a power window amplifier circuit board for a Nissan Quest. The circuit board is relatively small, it has a few active component, most of which can be identified by simply ...
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1answer
64 views

pull to GND switch for PSU enable

I need a circuit to toggle an control line on a PSU. The existing control line turns the PSU OFF when pulled to GND, the PSU is ON when the control line is floating or between 2.5V to 5.5V. I want to ...
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2answers
472 views

What is the purpose of diodes D1 and D2 in this 8 Ohm amplifier circuit?

What is the purpose of diodes D1 and D2 in the 8 Ohm amplifier circuit below? Visit ZL2PD No IC Audio Amplifier for more information of this circuit.
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1answer
168 views

Choosing a transistor for a low power application

simulate this circuit – Schematic created using CircuitLab I have looked at a few guides, both on this forum and elsewhere, for choosing a transistor. I know to look for things like HFe and ...
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3answers
343 views

PNP wont turn off

I am somewhat new to electronics and I've got a problem. I made a H-bridge, I'm trying to control it indirectly with my Ardunio through a PNP (BC557). The motor spins once PNP is in place however the ...
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1answer
1k views

How can a PNP transistor work as Amplifier? [closed]

I am not understanding the concept of using PNP transistors as amplifiers. Could you please help me in this? Thanks
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2answers
318 views

Current gain characteristics versus Collector Emitter voltage. Where is the transistor saturated? Can a transistor be saturated with a VCE of -10V?

I'm fairly new to transistor usage and determining stages of operation for a BJT. However, from what I've learned, in order for a BJT to be saturated, both junctions need to be forward biased, and ...
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1answer
215 views

What is the best between a transistor and a pmos and which resistances

I need to create a switch to power on or off a moisture sensor. PIN 10 is HIGH or LOW to trigger either the transistor or the PMOS My sensor consume about 0.6mA Moisture sensor information My ...
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2answers
302 views

Maximum load resistor for a given single transistor circuit

Following parameters are given for the above circuit: R1=8.2 kΩ, R2=5.6kΩ, RE=2.7kΩ, VEB=Uj=0.7V, Vcc=10V, β=200 The question asks the maximum load resistance RL for the transistor in active mode. ...
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1answer
124 views

Question regarding transistor codes

I needed a 2N 2222A transistor. And from a electronics shop I got the transistor with following symbols, KSP 2222A -1426 I have already searched and know that KSP is the name of a manufacturing ...
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2answers
834 views

Complementary Transistor Pair

I am wondering, why is there no complementary transistor pairs to buy, since their use as individual devices is pretty common in audio amplifier applications. So for complementary transistor pair it ...