Questions tagged [darlington]
A structure containing two of the same BJTs, used for increased current gain compared to a single BJT.
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What have I built exactly?
I was fooling around with cmos inverters and then I saw what was happening when I tried to increase the gate voltage past Vdd/2 so I tried to take advantage of it and connected it upto a darlington ...
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Designing a 12AU7 Tube Preamp with Stable 120V Plate Supply – Seeking Suggestions
I'm designing a small preamp using the 12AU7 tube. For my plate voltage, I'm using a rectified output of 132V DC from a transformer, which I want to regulate down to a stable 120V. The goal is to ...
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Darlington transistor for low side switching of LED light
I have a circuit that is aimed to switch on a 48V LED light (front/rear) for a bike.
Basically a low side switch using a darlington transistor to be controlled by a 3.3V microcontroller.
On my ...
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Contactless AC line detection using a single transistor
I have seen circuits that are used to detect the presence of AC voltage without any contact, like the one below.
Non-Contact AC Line Detector using BC547
I have tested this circuit and it works fine.
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Darlington control with Op Amp and DAC
The purpose of my circuit is to control(current) a servo motor with the 4096 steps of the DAC MCP4725. Currently this circut is not turning on the NPN Darlington, I don't know why that.
The DAC is ...
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Darlington NPN preregulator for LDO step down 42v to 12v ~ transistors keep blowing up
this is a follow-up from the original post about this circuit which can be found here. the purpose of this circuit is to reduce the voltage to a lower level that is more palatable for the LDO. and it ...
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Output Current of Darlington Amplifier
I'm working with Darlington amplifier and when I try to simulate the circuit using LTSPice. The result is as below. When I remove the resistor at Emitter of Q2, the current is constant, but if I add a ...
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Netlisting errors in Pspice "ERROR(ORNET-1163): Unable to create netlist file."
I'm simulating a simple BiCMos Darlington Circuit from the "Analysis and Design of Analog Integrated Circuits" book in Pspice Orcad Software. I don't know why when I'm trying to run the ...
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TIP120 excessive voltage drop
I've been trying to make my own H-bridge using a TIP120. With the test circuit below, I was expecting to get ~6V at minimum across the resistor but I'm getting less than 3V.
The circuit still outputs ...
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How is this circuit generating a voltage seemingly from nothing?
I made a Darlington pair from two 2N3904 transistors, and connected the collector (of the entire Darlington pair) to the 3.3V output of a breadboard power supply (powered by an adapter that plugs into ...
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Need help with audio amplifier design for loud volume
I'm trying to design an audio amplifier. The preamp stage is a voltage divider CE, while the power stage is a Darlington Class A:
My goal is to amplify a \$48.7\ \mathrm{mV},\ 1.07\ \mathrm{mA}\$ (...
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How to determine the collector current limiting resistors for the Darlington's pair of transistors?
How were the resistors in the circuit calculated?, I would like to come up with a similar circuit but for a 5VDC power supply, and I would like to resize the resistors as per my load requirement, my ...
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How to design BJT common collector amplifier?
I am working on a school project and I am struggling to design what is supposed to be an easy CC-amplifier. All other parts of the circuit are calculated and should work. The power amplifier is what's ...
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Problem with Darlington Pair Experiment using Two BC547Bs
simulate this circuit – Schematic created using CircuitLab
In schematic (a), the LED illuminates dimly on holding the 2 probes and gets brighter the harder one squeezes. My understanding of why ...
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Finding Vbe for a darlington pair?
I'm looking for guidance for a homework problem. I have invested several hours into it, and the feedback from the professor hasn't been constructive. I modeled the circuit with LtSpice to verify my ...
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Darlington configuration using BJTs [closed]
Does a Darlington configuration using two BJTs, say a BC548, override the total power they could dissipate?
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Darlington Amplifier circuit (TIP 120) [duplicate]
I'm trying to wire a darlington TIP120 just to see if I can get the 1000 hfe dc gain at 100mA like it said on the data sheet. I made the circuit like it appeared in the data sheet, but wasn't ...
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Darlington transistor configuration
Can two 2n2222a transistors output more than 1amp of current if biased properly; supposing 1.4v to 1.5v is applied to the base?
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What is the use of the PNP transistor in this circuit?
The schematic below describes the structure of a single channel from the 8-Channel Darlington Current Driver TD62783A.
Image source: 8-Channel Darlington Current Driver TD62783A
I understand most of ...
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switching multiple supply voltages on same low-side darlington array IC
Say I have an MCU switching a couple SSRs using the ubiquitous ULN2803 at 5V on the "common" pin, but I'd like to switch a 12V mechanical relay with the same chip as well. Checking the ...
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What is the purpose of the resistors in a Darlington transistor [duplicate]
I come across with a transistor circuit as shown below. Does anyone know what is the purpose of R1 and R2?
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Variable output voltage regulation - does this solution make sense?
I want to use a switching power supply that has a fixed 24VDC output. I want to add a simple circuit that will give me an adjustable voltage between 0-24VDC. The power supply allows the consumption of ...
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Driving 10ch outputs with 5V AVR
I use a 5V AVR (ATmega1284p) to measure some data. Depending on the data I would like to switch one of 10 outputs.
Each of these outputs should have a LED (as an indicator and for debugging purposes) ...
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Protecting voltage regulator circuit against broken neutral
I have a simple voltage regulator. The voltage input is on the left side and the output is on the right side.
Input voltage (Vin) can be as high as 400V (rectified AC) and output voltage (Vout) is ...
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Microcontroller driven circuit that opens a charging circuit and closes a resistive circuit simultaneously from the same I/O pin
I'm working on a project that charges a capacitor with an external 5V DC power supply and then discharges it across a very low resistance. Since I don't want to close the circuit while the power ...
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Increasing current from a linear regulator IC
I'm designing a device that will use a common "yellow" 20V tool lithium battery pack (which I know contains an array of 18650 cells, and is actually an 18V pack,) both for its internal ...
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Why don't we use MOSFETs in the Darlington configuration?
Why is it not practical to connect the two drains of the MOSFETs together? Is it not practical to connect the source of one MOSFET to the gate of another?
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Linear regulator darlington
I don't know if such a regulator should be sinking current in the first place,
I can't get any example on the web that shows a similar example of an op amp sourcing current
to the base of the NPN to ...
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Darlington Pair TIP41C at op amp output not amplifying current
I am trying to make a variable voltage regulator with the TL081CP op amp. When I add a single TIP41C transistor the max current I can get at the 20 ohm 20 W load is about 625 mA.
But when I want to ...
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How to drive a small 8 Ω load given a CE-CE amplifier?
I want to amplify a 25 mVpp input signal with a source resistance of 1 kΩ to anywhere from 2.5 Vpp to 3 Vpp to drive an 8 Ω load (though at this point I am willing to sacrifice gain to just drive my ...
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PNP TIP126 transistor hot to touch while in use
I have a 7-segment mechanical 'vane' display andbgot it working using a circuit originally suggested to me here. The diagram below is a slightly modified version.
Each vane draws around 0.2A of ...
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I made a darlington transistor in LTspice. But, that has different values from theoretical values
As you may see from title, I made a darlington transistor like this.
I set each transistor(Q1 and Q2) to have β = 150.
So, total darlington β must have 22500 or thereabouts according to a formula ...
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Is this TIP102 Darlington Transistor Circuit Correct?
Objective: Power on Pi Zero by setting pin 13 of Arduino to HIGH.
I plan on using the Arduino to measure the Li Ion battery voltage and, if well charged (so, say over 4V), then it will pull pin 13 ...
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Darlington triplet - static electricity detector?
simulate this circuit – Schematic created using CircuitLab
I built this circuit. Different versions of this exist on the internet, some using an MPF-102 JFET instead of the 3 NPNs. The various ...
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Darlington Triplet
I was playing around in Falstad Circuit Simulator with powering a 2.5V incandescent lamp with a Darlington Triplet. I tried it two different ways and got slightly different results.
I'm not sure if ...
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Switching 3.3V 150mA efficiently
I have a load (from 20 LEDs with 20 resistors) that I want to switch on/off as a single block, using a GPIO pin from a micro-controller.
I have measured the current to be 145mA at 3.3V Vcc.
simulate ...
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Darlington Transistor hybrid parameters from BJT h-parameters
I'm trying to analyze the Darlington transistor model, so I need to calculate the hybrid parameters for this circuit.
For example $$h_{ie} = \frac{v_{be}}{i_b}\bigg\rvert_{v_{ce=0}}$$
So which is the ...
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What does a Darlington pair do in a DC power supply circuit?
I really don't understand the role of the Darlington pair (T1) in this circuit. As it is a DC power supply circuit, I always thought that the pair is useful to have a high gain in audio and AOP ...
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What is this unusual NPN-PNP transistor pair?
I was looking for the datasheet for a transistor I'd discovered during some reverse engineering, a DK52T. Unfortunately I can't find its datasheet, but I found one for the DK52D. See the image below; ...
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How to set loading(resistance) when i try to simulation Darlington pair limit current between Voltage 9 to 36
How do I set my loading (R13) value for simulating Darlington limit current between 9 to 36 V?
If there is no loading (R13), the result of Q1 current (C to E) would not show correctly, but a placing ...
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How does a Zener diode and NPN BJT control circuit provide current limit or thermal shutdown via an NPN Darlington pass transistor?
Background Application: 1995 Ford Ranger Manual Control Blend Door Actuator
This 1 page pdf guide shows the block level function of a manual blend door actuator (my component is from a Ford Ranger.)
...
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Unused pins of FMBA14
I am using NPN Darlington array FMBA14. I am only using B1,C1 and E1 pins for my application. The other pins B2,C2 and E2 can be left floating?.
Can someone suggest anything on this?
Thank you
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Replacing Darlington with MOSFET for capacitive discharge circuit into a solenoid?
I have the following circuit and criteria and am wondering if it makes sense to replace the Darlington transistor with a MOSFET, and if so how would that change the circuit? This circuit turns on T1 ...
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Have I understood transistors correctly?
These are what I know and what I've concluded about transistors. Correct me if I'm wrong:
It's all about current. When we have a determined voltage differential source, BJTs are used to boost the ...
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Simple question about Darlington BJT
I have this circuit for a pasive balancing battery cell with 2 PNP Darlington transistors with switching role.
When I close the circuit with the optocoupler the transistors are open.
R7 and R1 are ...
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Which one would be better for 3.3V outputs among ULN2001 and ULN2003?
I intend on driving 24VDC relays with darlington arrays of the ULN200X series. Since the darlingtons will be driven by a 3.3VDC outputs I am hesitating on whether I should choose ULN2003 or ULN2001.
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H-bridge failing under load
I have made two H-bridges following this schematic.
I have replaced:
TIP107 with TIP147
TIP102 with TIP142
The opto-couplers are P785.
I have not included the diodes as they are internal to the TIP.
I ...
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Making a Darlington transistor (eg: TIP120) with D882 to drive 12V LEDs with 3.3V or 5V input RPi
I am getting into circuits and trying to improve my knowledge but even though it might sound like a silly question but here is my story short:
What I am trying to do
I am building a circuit to drive ...
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Touch switch for hanging lamp (touching metal bar): Ideas?
A few years ago, we have bought an IKEA Glimt hanging lamp that operates with halogen lamps. It has a "touch dim" functionality, so when a person touches the metal bar of the lamp, it dims (...
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Darlington biasing design error in a commercial frequency counter oven control circuit?
I am repairing a commercial frequency counter (brand to remain anonymous) that had the crystal oven visibly overheat. There is a small PCB in the oven that holds the crystals, the oscillator circuit, ...
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