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26 votes

How to convert a digital signal from 5V to 24V?

Converting to a "24 V signal" is missing the point. The real problem is driving a 24 V relay from a 5 V digital signal. Fortunately, that is easy. Here is one way: You didn't say how much coil ...
Olin Lathrop's user avatar
20 votes
Accepted

Is it a good idea to connect a line buffer to ground?

You should always tie unused inputs to a valid logic level. That could be tied to GND or to the VDD voltage rail. Never leave unused inputs floating in that it can cause excessive power dissipation in ...
Michael Karas's user avatar
15 votes

Why are USB devices slower than 480 MBit/s

This is a very old topic, but it has no answer yet. This is my attempt: Why are today's implementations not capable of streaming at 53 MB/s? The calculations are nearly fine, but you are ...
Ale..chenski's user avatar
14 votes

How to drive 1080p with only 540 pins?

Typically there are long skinny driver chips for row and column. They may be on the outside COF (Chip-On-Flex) or inside COG (Chip-On-Glass construction) the panel itself. Here's an HD TV panel from ...
Spehro Pefhany's user avatar
13 votes

Resistors getting hot in this MOSFET driver circuit

Here is your circuit being discussed: R3 and R5 should not be getting "hot". Do the math. Even if Q1 were a perfect switch, there would only be 5 V across R3. (5 V)2(1 kΩ) = 25 mW. Unless ...
Olin Lathrop's user avatar
13 votes
Accepted

Does a MAX485 need decoupling capacitors?

Yes. All almost ICs need decoupling capacitors. Devices such as these '485 drivers especially need them due to the current surges the device experiences when switching the signal states due to the low ...
Michael Karas's user avatar
13 votes
Accepted

Is it OK to use internal pull-down as part of voltage divider?

Schematics like the one that you show should be regarded as simplified schematics - the actual implementation is likely more complex. Anything that is not specified in the tables, graphs or text --- ...
le_top's user avatar
  • 3,161
12 votes

Resistors getting hot in this MOSFET driver circuit

Figure 1. When Q1 is off both Q2 and Q3 are forward biased (green) and will turn on. The result will be shoot-through the two transistors (red). If the supply voltage doesn't collapse (1) will be at ...
Transistor's user avatar
  • 175k
11 votes
Accepted

When do you need buffers/drivers on buses in a microprocessor design?

Large is when the processor cannot drive the various signals properly and that comes down to a number of things but primarily it is the number of devices on the bus. They all present a load to the ...
Peter Smith's user avatar
  • 22.2k
11 votes
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What vendors make anti-counterfeit drivers for USB-UART ICs?

Prolific did, we ended up holding some "PL2302" USB-RS232 cables that were "Linux only" around 2010 some time, the windows driver didn't try to break the chip. I recall Silicon ...
Jasen  Слава Україні's user avatar
10 votes
Accepted

MOSFET not turning off

Even though this a a 'simple' circuit there are still lots of things that can go wrong. Finding a fault is quite an art. Let's start by breaking the circuit into two parts. The BJT switch and the ...
JIm Dearden's user avatar
10 votes
Accepted

I²C bus buffer vs extender P82B715 vs. P82B96

82B715 is a rather older device, with a limited specific function: It increases the bus current 10x. It does not however improve the threshold noise immunity (threshold levels remain the same). We ...
Henry Crun's user avatar
  • 5,353
10 votes
Accepted

Is this circuit linear or not?

\$R_{\theta JA}\$ is one small part of the story. The main part of the story is \$R_{\theta JC}\$ (at 1.5 °C/W), because this is the junction-to-case thermal resistance and it adds to the heatsink ...
Andy aka's user avatar
  • 453k
10 votes

Is it a good idea to connect a line buffer to ground?

With any CMOS logic IC, you MUST connect unused logic inputs to a known logic level. You may connect unused inputs to either High or Low, whicever is convenient (or whichever is necessary to make the ...
Peter Bennett's user avatar
10 votes
Accepted

How Does an Adjustable Transistor Size CMOS Driver Work?

The approach to do this is alluded to in the datasheet snippet you linked, which mentions "fingers", or separate parallel gates in a wide MOSFET that forms the output driver. These fingers ...
nanofarad's user avatar
  • 19.4k
9 votes
Accepted

Russian к2лн641 VFD (Vacuum Fluorescent Display) driver pin out help

I'm Russian, so I'll help you out with this one. First of all, the first link google gives when I search for that is the museum of soviet electronics. Interesting choice of parts haha. Secondly, this ...
Ilya's user avatar
  • 3,523
9 votes

Transistor Driver - what is the purpose of Q2 on the included schematic?

Q2 is not simply a B-E diode, it is an emitter follower. Without Q2, R1 pulls up with about 10mA, driving the load rather modestly. This is okay for small loads, like logic-level inputs, or even ...
Tim Williams's user avatar
  • 32.1k
8 votes
Accepted

Trying to increase amperage of Arduino Uno digital pin (20mA) to control a cabinet lock that is rated at 12v / 2A

simulate this circuit – Schematic created using CircuitLab All you need is a Logic Level MOSFET. I use N-channel AOD5xx to sink current thru a load. 508, 510, 514, any would work well and can ...
CrossRoads's user avatar
  • 3,571
8 votes
Accepted

Relay coil fast demagnetisation

The higher voltage you allow the coil to spike at, the faster the current will turn off. Something, usually a transistor, is driving the inductive load. You have to keep the maximum spike voltage ...
Neil_UK's user avatar
  • 165k
8 votes

What vendors make anti-counterfeit drivers for USB-UART ICs?

The question is certainly of historical interest but of little current relevance. It’s troublesome to design for anything but standard USB class - CDC. Even if say FTDI may not be offering a chip for ...
Kuba hasn't forgotten Monica's user avatar
7 votes

How to drive a linear actuator in both directions

Use an H-bridge. It is cheap and straightforward to build. http://www.bristolwatch.com/k150/port4.htm I use this for high current switching: http://www.bristolwatch.com/k150/pics1/mosfet_hb2.png ...
user400344's user avatar
7 votes

Resonant Solenoid Drivers

In no case would a coil driven at resonance be better than one driven with DC. This is presuming that the job of the coil is to make a magnetic field, and that this requirement exists regardless of ...
Olin Lathrop's user avatar
7 votes
Accepted

Driving a 6V relay from an 3.3v GIO pin of Raspberry PI3

The item you linked in your question is a logic level converter and so this would probably be unsuitable as it wouldn't be designed to work with currents around 100 mA. The simplest implementation I ...
Andy aka's user avatar
  • 453k
7 votes

How to convert a digital signal from 5V to 24V?

The circuit in your schematic will work fine except that the relay coil should be connected to the output and to +24, not the output and GND. Pin 9 is not shown on your schematic and must, of course, ...
Spehro Pefhany's user avatar
7 votes

Ohms law and LED driver efficiency? How can this possible be true?

He's trying to sell you something that consumes > 30 W as a "30 W driver", whereas it actually can only supply less than 30 W. The ratio between power that goes in and goes out is called the ...
Marcus Müller's user avatar
7 votes

Simple LED driver, transistor and GPIO

BJT's as switches aren't complicated. One input is the value of your power supply voltage -- call it \$V_\text{CC}\$. Another input is the desired operating current of the LED -- call it \$I_\text{...
jonk's user avatar
  • 77.8k
7 votes
Accepted

Output drive vs. absolute max output current

On page one, the datasheet is telling you that the output can supply 4mA and still respect VOH(min). In other words, it can supply 4mA and still provide an output voltage that will be recognized as a ...
user57037's user avatar
  • 29.3k

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