Questions tagged [transistor-array]
Anything related to transistor arrays, i.e. small-scale integrated circuits containing a limited number (usually 8÷16) of well matched transistors. They are used for applications where component matching is paramount or to simplify the layout of a design where many transistors must be used in the same configuration.
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Driving an array of resistive loads on high side with as little parts as possible
I'm trying to switch an array of resistive loads at 12V as fast as possible using least amount of parts due to limited board space. I have tried to find sourcing darlington transistor pairs but they ...
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3answers
107 views
Problem of transistor thermal runaway in parallel connection
simulate this circuit – Schematic created using CircuitLab
I wanted to use two transistors in parallel to increase current rating.
So I simply put two transistors in PCB design. Later I found ...
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1answer
52 views
Am I doing something wrong or is there something wrong in this PMOS SPICE model?
I am trying to create a PMOS in Multisim based on a SPICE model.
The component itself is a DMC2400UV-7 from Diodes Incorporated (MOSFET N/P-channel array for 20V.)
The NMOS simulation didn't give me ...
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1answer
48 views
ULN2003 IC , should I stack it or should I divide the load?
I am trying to drive 7 led strips.
I saw in the datasheet that the ULN2003 IC can supply 500mA per channel. In reality this would be limited due to heat dissipation by the IC.
Should I drive 3 led ...
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1answer
108 views
Confusing 2N3773 transistor connection
We have a battery capacity tester (upto 30V battery & upto 25A discharge current) which when connected to a battery causes a heavy spark even in off condition (Control card supply off).
We have ...
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1answer
59 views
How would I switch between either of my two outputs into one input?
I am trying to design a circuit which will switch between two RGB outputs into a CRT TV's neck board. Each of the two outputs has three pins. I have tried using the 2N3906 PNP transistor, and it works ...
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1answer
88 views
Multi Transistor Circuit
I made a multistage transistor circuit to see, with such a high gain, what the output would be?
(Bottom Terminal to +5V, Top Right Terminal to Gnd)
I've seen circuits with three transistors in this ...
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153 views
Is it necessary to opto-isolate a darlington array output?
I've got the following circuit going:
A Vishay opto-isolator (CNY74-4) that takes input from buttons that work on 24V, and outputs to microcontroller pins (an Olimex ESP32-PoE-ISO in my case).
A ...
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1answer
360 views
How do pixels in a LCD display are individually controlled by a electrode?
How do tiny subpixels in the Led displays are controlled by those indium tin oxide electrode.How do they provide different voltage for each pixel
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1answer
197 views
led chaser with non-mechanical shut-off option
I've seen thousands of standard led chaser circuits online but I haven't seen one in which I can shut off all LED's in a non-mechanical way.
I'm wiring one pin of my chaser up to a microcontroller so ...
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1answer
89 views
MAT01 Matched NPN Transistors - Substrate bias voltage
I am working on a logarithmic amplifier based around the MAT01GHZ matched pair.
In the datasheet, a note states:
The collector to base and collector to emitter leakage currents can be reduced by a ...
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2answers
215 views
Damaged TPL7407LA Transistor Array (*Updated With Scope Testing Images*)
Application We have chosen the Texas Instruments TPL7407LA to drive groups of LEDs for an automotive lighting solution. The TPL7407LA inputs are connected to +12 VDC input signals to trigger the ...
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1answer
51 views
Controling where sound goes (darlington array)
source of sound (dealing with multiple sources) and six speakers. I want to control to which the sound goes.
The system has a DC offset with both sides of the wave within positive range
Question is ...
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1answer
533 views
What is the purpose of connecting the collector of an NPN to the base of another NPN? [duplicate]
In the circuit below, in the section inside the green circle,
it seems there's no purpose for connecting the NPN transistor's collector, to the base of the other NPN transistor on the right.
...
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2answers
135 views
DRAM -> However all I want is the capacitor array, (or does a circuit like this even exist)?
Sorry, this is a very odd question, I've however exhausted my google-fu and I don't even know what question to ask to get the information that I'm looking for. (I'm a programmer so pardon the lack of ...
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3answers
815 views
4017 Decade Counter Into Transistors Problem
I'm attempting to use a decade counter with each output connected to the base of a set of transistors in parallel. So that the counter will count up, and will allow current to pass through one ...
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2answers
494 views
Why is it not possible to find pnp bipolar and n channel mosfet transistor arrays in IC package?
I use a lot of 2N3906 pnp bipolar transistors and 2N7002 n channel mosfets on my pcb. I was suprised to see that there are no cheap and commonly available IC packages for these common transistors as ...
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Can I expect SMD components from a same manufacturer to be identical?
I'm working on a project which requires at-least 2,000 ambient light sensors, and instead of using a microcontroler to manage and monitor the whole system I just want to amplify the output of sensors ...
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1answer
176 views
Array switch circuit design
I am attempting to design an "array switch" where a user can toggle a switch and a different array of LED's are turned on based on multiple reference traces. The picture is my best attempt so far. I ...
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2answers
301 views
How to efficiently power and arrange 100 multi chip LEDs in 6 different colors each color runnig off their own transistors
First time on here hope I have given sufficient information. I am trying to power 100x 5W high power multi chip LEDs and 8x 3W high power LEDs. I would like to do so off of 120v Ac house plug. The ...
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2answers
410 views
ULN2003 Used for security door magnets
I am building a project that will lock several cabinet doors using ULN2003AGP chips and security electro magnets similar to this:
AGPtek® 60kg 130LBs Holding Force Electric Magnetic Lock
This magnet ...
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1answer
3k views
ULN2803 - do i need COM(VSUP) for relays ?
I'm building a relay board with SRD-03VDC-SL-C relays and an ULN2803 Darlington transistor array. As I am a beginner I don't understand the purpose of the COM pin?
In the datasheet VSUP (Coil Supply ...
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3answers
614 views
Can I somehow use one PWM output to set various LEDs to different brightness?
I would like to build a project in which 15 groups of LEDs are set to a brightness level. I have an Arduino with digital PWM outputs (which can mimic a range of voltages.) How can I do this?
One ...
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1answer
831 views
Why my solenoid valves open only if power is turned on at last?
I have a set of eight 48Vcc solenoid valves that I'm controlling using an Arduino. The open and close signals are sent using the Arduino's SPI lines, which are connected to a circuit composed by a ...
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175 views
What it is the maximum “real” current by the collector that can be drawn from ULN2067B
I am building a 5-volt-to-24-volt DC converter using ULN2067B. According to the datasheet this device can support 1.5 A per darlington per collector.
Does that mean that all the darlingtons can ...
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1answer
675 views
BJT pre-biased arrays slower than discrete?
I've got a circuit that works - it's job is to convert a TTL square wave into a +/- 12 volt square wave.
simulate this circuit – Schematic created using CircuitLab
Note that the transistors ...
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1answer
2k views
Questions about a simple LED circuit using the ULN2003A
I'm a newbie, and am trying to drive several independent LEDs using a transistor array in a 5-volt CMOS circuit. Here's what I've come up with, showing only the first LED:
In the schematic, ...
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1answer
948 views
Why might the collector-emitter voltage for this transistor be so high?
I'm attempting to use an NPN transistor as a switch, to drive an LED load. So I am only interested in the off and saturated states.
My understanding is that when the base-emitter junction is ...
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1answer
396 views
Unable to keep 2nd shift register in chain of 3 from “leaking”
I am working on a word clock, and I am using 3 shift regsiters (CD4094BE) and 3 darlington transistor arrays (ULN2003A) to control whether or not 21 different words are on or off. The words consist of ...
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1answer
526 views
Custom device with multiple gates tied together in Eagle
I'm trying to create a transistor array device in a small library I'm working on in Eagle. The device has five P-Channel MOSFETs. The source of each MOSFET is internally tied together and connected to ...
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4answers
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Any IC similar to ULN2003A with latch or enable/disable?
I'm working on a project that uses a ULN2003A (darlington transistor array) and I need to enable/disable it. The point is that ULN2003A does not have enable/disable pin.
I think that a IC with latch ...
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1answer
424 views
Fet array operation [closed]
Can anyone explain to me the operation of the following FET arrray .
http://www.diodes.com/datasheets/DMN2019UTS.pdf
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2answers
3k views
What IC is good for driving an array of smaller solenoids?
I have a 7 segment display where all segments are driven with a solenoid. In order to switch each segment I have to pulse a short current on the solenoid. To change the segment I have to pulse it in ...
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3answers
932 views
Darlington Array IC that can sink 1.5A
I am looking for a darlington array IC like the ULN2803a that can sink up to 1.5A. It needs to be in a DIP. Any recommendations? Its needed because i am driving a stepper motor and requires 1.2A per ...
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1answer
771 views
Why do 0v have to be connected when using two power supplies and ULN2803A?
The other day I was playing with a ULN2803a and a stepper motor. I spent ages trying to work out why it wasn't working and why i was reading ~14V as an output on the PIC I was using. So why did I have ...
