Questions tagged [darlington]

A structure containing two of the same BJT, used for its increased current gain compared to a single BJT.

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2answers
393 views

How to localize cause of short circuit in proto board design?

I'm working on a basic application with a microcontroller controlling several components including a: 12V DC pump (Darlington array) 12V PWM fan (Darlington array) humidity sensor (I2C) and LED ...
0
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2answers
355 views

Guitar Amplifier Peavey Backstage Plus

The fuse of this guitar amplifier blows. Changing the output transistors had the amp working for a while, but then after a while the fuse blew again. The output transistors that were changed are new....
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2answers
157 views

QUCS Darlington pair

I'm modeling a Darlington pair in QUCS to understand better how to use it in practice. The model is below: The DC analysis predicts a current in the base of T1 of about 1uA and a collector current on ...
1
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1answer
37 views

Powering 4 modulated IR LEDs through transistor

I've done some research but can't seem to find an answer to my specific problem. I'm using an Arduino as a beam-break sensor. In order to do that it modulates the IR LED at 38kHz by code and listens ...
1
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1answer
79 views

How to get current flowing through the darlington transistor as a switch for a stepper motor?

I have a 17PM-K307-05VS unipolar stepper motor. I am building the driver for the stepper motor. The exact rated voltage and current are unknown, it seems the motor is old or discontinued, but the ...
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1answer
60 views

Drive a resistive heater from a low power IC

I'd like to drive a resistive heater using an IC operating at 3.3 V. The heater may need to dissipate up to 18 W, and will be powered by a 28.8 V battery. The IC is able to generate PWM signals, but ...
0
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1answer
50 views

Understanding the Design of Common ULN2803a Motor Driverboards (use of the capacitor in particular)

I'm studying a popular motor driver board based on the ULN2803a Darlington Array chip (top and bottom pictured below). A capacitor is between the common diode/flyback trace and GND. Does the ...
0
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1answer
398 views

Latching/Non-Latching Relay Driver Circuit with darlington optocoupler

I'm designing a circuit where an ESP8266 controls two types of relays, a single coil latching relay and a normal non-latching relay. The relays are power relays use to control low power electrical ...
0
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1answer
414 views

calculating input resistance of darlington pair (TIP120) from datasheet values

I've tried to find a way to calculate the input resistance of a darlington pair (TIP120), using the values given in the datasheets. https://www.onsemi.com/pub/Collateral/TIP120-D.PDF After Searching ...
0
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1answer
68 views

Darlington Transistor \$ A_I , A_V \$

For a darlington configuration: $$h_{ie}=1k,h_{fe}=\beta=50,h_{oe}=25 \times 10^{-6},h_{re}=0 \quad for \quad both \quad transistors,R_L=3k.$$ how can we find the current and voltage gain? My ...
0
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1answer
40 views

What is this UP 4B2 smd chip in dfn8 case?

Acts probably as a driver to power the motor. There a two of this kind on the board. One burned, the train drives only in one direction.
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1answer
216 views

Circuit to boost PWM voltage using ULN2803a

I am trying to convert 5v PWM signal to 10v using ULN2803a IC. My target device (a dual channel LED light)expects two 10v pwm signal and GND via a 3.5mm audio connector. The part I am struggling with ...
1
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0answers
539 views

Esp8266 and uln2003 restarts

I am trying to drive 6 LEDs from an Esp8266 (esp201 break out board). Because of the Limit current of 12 mA the esp can do i want to use a 7way darlington Array to Power the LEDs. I have programmed ...
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0answers
73 views

Find high current latch or use Darlington array?

Looking for best practices here. I'm building a common-anode LED matrix. I've got a current sink LED driver, and I'm looking for a latch that will provide enough current to drive an array of LEDs. All ...
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0answers
25 views

FG servo motor speed issues

I have been trying to get a 40-year-old turntable back to life, with relative success until now. Everything works fine but for an intermittent issue with the motor. The motor has two modes (for 33 1/...
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0answers
60 views

PNP darlington pair calculations

I have a 20ohms discharge resistor connected to my PNP darlington pair. I have simulated the circuit in my mobile (every circuit app).please find the attachment for circuit. But here I'm unable to ...
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0answers
91 views

Darlington Transistor TIP142 same type but different values

I have a bunch of Darlington NPN Transistors TIP142 that are removed from two separate identical boards. The 1st one have the TO−218 CASE (left side of the image) and the 2nd the TO−247 CASE (right ...
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0answers
101 views

Darlington pair. Purpose of components

Giving the following schematic: What is purpose of R1 and the diodes ?
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0answers
71 views

How to test if a, in circuit, complementary darling transistor is still functioning properly?

I think a transistor broke down. My knowledge of electronics is not sufficient to solve my issue, so it seems. Hopefully some better educated mind can help me on this. This question is about ...
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0answers
258 views

Driving a DC motor (in one direction) with a microcontroller pin and an opto-isolator

I'm supposed to design a circuit for driving a DC motor with an opto-isolator and a microcontroller pin. The motor is supplied with 12V, and its power is 5W. The opto-isolator has to isolate the ...