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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2answers
97 views
Will the PNP and the diode circuit behave differently?
Need to repair a legacy system that has been discontinued and am considering replacing the PNP based circuit with the diode based circuit.
The input signal (max. freq = 20Khz) is applied at IN and is ...
0
votes
2answers
54 views
Common Mode Differential Analog Input
I'm using the LTC5598 IC for modulation. I am confused as to how to properly feed my BaseBand analog signal into the chip.
According to its datasheet:
The circuit is optimized for a common mode ...
7
votes
1answer
1k views
Can the Common Emmiter Amplifier use a PNP Transistor instead?
This is a simple Class A amplifier using an NPN transistor:
Is there a way this can use a PNP transistor, instead (with only 0V and +Vcc, not 0V and -Vcc)? Why or why not?
5
votes
4answers
537 views
Can I use a PNP Transistor with an Electret Microphone to get an non-inverting output for my Arduino?
I'm looking to simply read the generic sound level from an Electret Microphone. I've seen a number of schematics with NPN transistors, that will provide an inverted output (~5V when quiet, ~0V when ...
3
votes
1answer
81 views
Connecting a N.O. grounded switch to a scanning switch matrix
I am working on a project that includes a scanning switch matrix. It also includes a joystick with an integrated push button. I am out of IO pins on the micro, but there are gaps in my switch matrix, ...
3
votes
1answer
280 views
Shortcircuit protection with PNP
R1 became RS
R2 bacame R
1)Is this a correct shortcircuit protection?
2)What is the max current that can flow before the transistor enters in saturation?
3
votes
2answers
112 views
Voltage at common node in transistor
This is a rather elementary question but I think my fundamentals are not clear on this. What is the voltage at the common node?
Firstly, I thought voltage was taken across something i.e it's taken ...
3
votes
3answers
304 views
Why not to use a P-Channel MOSFET in this circuit?
Why not to use a P-Channel MOSFET in this circuit? It makes more sense, to me since the MOSFET act as a resistor when turned on which is better then the constant volage drop of a PNP.
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1answer
94 views
Will a MMBT5087 saturate with a 1K resistor in the base?
I am using the configuration in picture and the MMBT5087 PNP transistor. I am not using the top base resistor, just the lower one, so there will be 5V on the base.
My question is: Using a 1K ...
3
votes
2answers
159 views
How to calculate a PNP transistor thermal dissipation?
I am working with a dual power circuit for using USB and a LDO at the same time with a PIC18F2550. The circuit is the same as the one in the PIC's datasheet. My question is:
How do I calculate the ...
-5
votes
1answer
283 views
Is it possible to attach PNP counter to an NPN encoder? [closed]
As a follow-up of my previous too generic question
I have a signal generator (shaft encoder) that has 2 NPN outputs.
I have a high speed counter that needs PNP signals.
How can I convert the encoder ...
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3answers
1k views
How can I convert a PNP to NPN transistor?
I have a circuit which requires a PNP transistor.
I only have an NPN transistor.
Is there a way to convert one to the other given that they have the same characteristics (apart from the npn/pnp ...
0
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1answer
93 views
Which part of a pnp-transistor is the buried layer connected to?
I am preparing for exam and one of the questions is this: "Which part of a pnp-transistor is the Buried Layer normally connected to?"
According to the lecture notes handed out, the correct answer ...
2
votes
4answers
763 views
PNP transistor to command LED
Usually I use NPN to drive LEDs but in my project I have to use PNP because the cathode of the LED is tied to GND.
Then I have a question, is it possible to have a command of 3.3V and the PNP tied to ...
0
votes
1answer
137 views
Exam question: measure amplifier \$h_{oe}\$ using a signal generator and oscilloscope
I'm running through some old exam papers at the moment and one of the questions are:
The parameter \$h_{oe}\$ is needed to calculate the output impedance of an amplifier. Explain in detail how to ...
1
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1answer
386 views
LM3915 to drive more LEDs / basic questions about PNP transistors in saturation
As a few others here, I'm trying to drive a few (10) LEDs from each output of a LM3915 vu-meter chip. I've read different posts, and it seems the universal recommendation is this great answer.
I ...
3
votes
2answers
471 views
Can someone help me understand this H-Bridge?
I have an old RC car but without the transmitter so I built my own Rx/Tx using MCU and 2.4Ghz transceiver, however, I want to use the car's original H-Bridge but not sure if I understood how that ...
1
vote
1answer
238 views
Pulling a pin to 12 V using 3.3V
I'm building a boost converter and want to implement a shutdown feature. The particular chip I'm using, LM3478, has a shutdown feature which is activated by a high level on the frequency adjust pin. ...
3
votes
3answers
560 views
Basic PNP transistor on a microprocessor output pin
I have a 5v microprocessor that needs a PNP transistor between it and the common anode of an LED display, as it can't source enough current to drive all of the LED's without burning up. I understand ...
3
votes
2answers
515 views
PNP transistor switching time - puzzler
Updated based on feedback with better screenshots (I hope) - I am also working on getting the files onto a file sharing site so they can be accessed at full resolution
I am really confused about the ...
6
votes
3answers
291 views
How to design for a component that says “Electrical Design: DC PNP” in the datasheet?
I'm not a guy from electrical engineering and I'm having a little trouble with a small garage project that I'm working on.
I want to use a photoelectric sensor to measure distances. I'll probably ...
1
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3answers
455 views
Do PNP transistors have low noise?
I read somewhere that PNP transistors have lower noise than NPN transistors. The majority carriers in NPN are electrons where as in PNP they are holes, so I thought the noise would be much be less in ...
3
votes
3answers
523 views
How to use PNP transistor as a switch for serial communication
I am trying to interface a 3.3volt TTY bluetooth dongle to my arduino. The dongle requires 3.3volt but the arduino's Tx and Rx signals are 5 volt. Apperently the 3.3volt is enough for the arduino ...
1
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1answer
159 views
Calculating node voltages
This question is somewhat modified from the original which was asked by someone else. Note that there is more to this than meets the eye. The OP07 or OP070xxx is a 30+ year old op amp, the transistor ...
7
votes
2answers
196 views
Is one circuit better than the other to drive the PNP transistor?
Of the two circuits, would you prefer one over the other?
1
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1answer
6k views
What's the difference between NPN and PNP transistors?
This is not a duplicate of this question.
I would like to know what the differences in their characteristics are. I'm thinking for example about their majority carriers (electrons for NPN, holes ...
4
votes
4answers
1k views
Is this a proper use of a PNP transistor?
I'm attempting to use a transistor to switch on and off an SSR, which in turns switches on and off a solenoid. I originally used an NPN transistor (2N222), but this caused problems when the MCU ...
9
votes
2answers
810 views
What's the difference between NPN and PNP transistors?
Suppose that I know how an NPN transistor works.
How different is a PNP transistor? What are the operational differences between a PNP and a NPN?
3
votes
1answer
797 views
Using a P-channel mosfet instead of a PNP
With the LPC1343 microcontroller (Cortex M3), there is a USB_CONNECT line which goes low when the micro is ready to connect to the computer via USB. This "soft connect" feature is implemented on the ...
4
votes
4answers
2k views
Switching relay with a PNP and TTL levels
I can not wrap my head around the fact how I can drive a relay (24V, 160ohm) with an tip32a PNP transistor which has TTL inputs from a controller.
I can easily calculate my resistors when I use the ...
