Questions tagged [sinking]

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0 votes
3 answers
613 views

"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 ...
Circuit fantasist's user avatar
2 votes
2 answers
69 views

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 ...
Rokas Sondaras's user avatar
4 votes
0 answers
58 views

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 ...
tcurdt's user avatar
  • 201
3 votes
6 answers
159 views

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 ...
John H.'s user avatar
  • 141
2 votes
1 answer
356 views

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 ...
user274774's user avatar
0 votes
2 answers
139 views

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 ...
Michel Keijzers's user avatar
0 votes
1 answer
647 views

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 ...
Michel Keijzers's user avatar
0 votes
3 answers
442 views

Choosing pulldown resistor for 74LS86

I am trying to build a half adder using a 74LS86 XOR gate. Initially I connected both input pins that I am using (9 & 10) on the 74LS86 to the ground rail using 10K ohm resistors. I then connected ...
meyerman's user avatar
1 vote
2 answers
2k views

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 ...
RegularNormalDayGuy's user avatar
3 votes
2 answers
130 views

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 ...
JoeChiphead's user avatar
1 vote
1 answer
196 views

Rotary Encoder - Power Source for small Fork Light Barriers with NI 9401 [closed]

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 ...
Discbrake's user avatar
  • 211
0 votes
1 answer
186 views

LED switch with externally controlled current from sinking output

My device has sinking output (Vcc=3.3V), the LED current (and voltage) is controlled by another device (a voltage controlled constant current source) as indicated at VLED. The LED IV curves (as ...
JoeChiphead's user avatar
0 votes
4 answers
2k views

Oops! N-channel Mosfet on sinking output

I have designed a simple circuit to drive LEDs using a MAX6964 I2C LED driver/GPO chip. Unfortunately, I somehow missed missed that the outputs are open-drain current-sinking outputs. This is not ...
JoeChiphead's user avatar
0 votes
1 answer
662 views

Is it possible to sink and source from one output pin using a darlington driver

Sinking and sourcing with a darlington driver I asked a question about sinking and sourcing LEDs while using a darlington driver. The images were slightly unclear so i have redrawn it. I had too many ...
Hasan Imtiaz's user avatar
-5 votes
2 answers
378 views

How to increase microntroller pin Source and Sink Capacity

I'm working on a project but I've hit a block now. I need to drive a total of 169 LEDs using 26 pins at worst case all may be ON at once. I'm afraid that this may fry the MCU since 200mA is absolute ...
Lokanath's user avatar
  • 412
1 vote
1 answer
183 views

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

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 ...
new bie's user avatar
  • 237
12 votes
8 answers
53k views

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 ...
Abhishek's user avatar
  • 153
4 votes
3 answers
3k views

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 ...
Dan's user avatar
  • 41
9 votes
2 answers
2k views

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 ...
Len Holgate's user avatar
  • 1,078
21 votes
6 answers
13k views

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 ...
user217's user avatar
  • 211