Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [sinking]

20 questions
21
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6 answers

current sourcing, current sinking

I'm a student studying electronics and I'm having trouble understanding the concept behind current sourcing and current sinking. We've covered it in a lab using a 7404 and an LED and all that. Just having trouble getting an intuitive understanding…
user217
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8 answers

Sinking and sourcing current

I have been reading that NPN transistors are sinking and PNP are sourcing devices. I do not really understand this concept. It says current source device connects load to Vcc and current sinking device connects to ground (low voltage). So does…
Abhishek
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2 answers

How to redesign a circuit to use a current sinking IC rather than a current sourcing IC

I'm building a serial servo controller to learn about electronics and assembly language as part of my hexapod robot project. Quite early on I decided that I needed more I/O channels than my ATTiny2313 that I was using at the time supported so I…
Len Holgate
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0 answers

Sinking an input when pulses are above a certain frequency

I'd like to use a liquid flow meter of type YF-S401 at 12VDC. It produces 1.7-35k pulses per minute (rise time: 0.04us, fall time: 0.18us). I want to trigger a sinking input of a controller board if the frequency is above a certain number. While…
tcurdt
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3 answers

Driving Relay Board with Shift Register (Shift vs Sink)

I am trying to drive some ebay bought 8 channel relay boards. They are pretty simple, have a launchpad or arduino toggle a pin and the board turns on. However, I need to use a shift register with them. I have absolutely no idea how to think about…
Dan
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3
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6 answers

PNP as an inverting sink

I'm using a 74LS137 to drive a 7 segment LED (common anode.) Since it's a sink, it "inverts the demux outputs" as desired: I want to wire-OR two outputs, but you can't do so directly for 74LS137 (correct?) so I need diodes: Doing so reduces the…
John H.
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3
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2 answers

LED circuit stopped working when expanded

I built a small prototype as shown in my diagram with the Si926 n-FET, 250 ohm pull up resistor. In my prototype board I have only 4 channels connected (only two shown). Only one LED is ever turned on at a time. When I set 3 outputs off (ground)…
JoeChiphead
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2 answers

Microcontroller sinking current from another MCU

I have two microcontrollers, the beloved ATmega328p and an ATtiny85. The ATtiny85 does power management (toggling power to main MCU, get buttons clicks, and other things). The ATtiny85 disconnects VCC from the main MCU. The main MCU (ATmega328p) is…
Rokas Sondaras
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1 answer

Will this optocoupler circuit work for sensor and DC motor?

I am working on a project in which I need to operate a DC motor and some ultrasonic sensors. I want to operate the motor using motor driver DRV 8871 by giving logic signals and read sensor value on controller pin. I also need to maintain isolation…
user274774
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1 answer

Led must be mounted SINK or SOURCE so as not to interfere with communications?

I used 3.3v microcontroller. I want to add TX LED and RX LED communication on RS232, RS485, TTL/CMOS. My question: Led communication must be mounted as SINKING or SOURCING on I/O microcontroller for avoid interfere in communications? Picture in…
new bie
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2 answers

Matching sensor output with PLC input

I am trying to add a height captor for a line of my production where I work. I found this Banner captor (QS30LLPQ) and it has 2 bipolar discrete outputs (PNP and NPN). Now, I am trying to decide which of those two outputs I should connect to the…
RegularNormalDayGuy
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Rotary Encoder - Power Source for small Fork Light Barriers with NI 9401

Task In order to measure the angle and calculate the angular velocity and acceleration of a large metal wheel with a rotational frequency \$f = 0.01 \ldots 1.00~Hz\$, I try to build a custom rotary encoder located on the axis of the wheel. The…
Discbrake
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3 answers

"Source", "sink" or both?

Having solved the mystery of "pulling" and "pushing" devices, it would be interesting to do the same with "sourcing" and "sinking" devices. Background A transistor with a constant base-emitter voltage represents a constant current source (to be more…
Circuit fantasist
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How to read this figure (UDN2981 max current)?

This question is related to this question: why-are-the-pins-of-an-udn2981-related? In the UDN2981 datasheet, the figure below shows the maximum current (page 14, bottom left picture). Does this mean if I connect 8 pins (thus using the lowest line…
Michel Keijzers
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LED ULN2803 thermal / heatsink questions

I'm intending to use LEDs of 5mm, which have a max forward current rate at 30 mA, or a value of 100 mA, with 10% 1 kHz duty cycle, in a circuit like the one below except some changes: STM32F103C8T6 instead of PIC 2N7000's instead of UDN2981 3…
Michel Keijzers
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