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1 vote

Power supply delivering more voltage than indicated even when loaded

It depends on the type of power supply. For example, an unregulated full-wave bridge supply with capacitor filtering,such as this, will charge the capacitor to 1.414 times the root-mean-square (RMS) ...
DrMoishe Pippik's user avatar
1 vote

Power supply delivering more voltage than indicated even when loaded

The most unexciting answer is that it's perfectly normal for a good old unregulated transformer supply. None of this fancy regulated linear supply or newfangled switch mode supply stuff we have these ...
Justme's user avatar
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0 votes

Power Integrations Spice Model

Power Integrations website Q/A: Spice files of ICs Posted by: atulp16 on 07/07/2020 Hi, As their is no spice files available of ICs online. How can we get the spice files of ICs so we can simulate ...
Spehro Pefhany's user avatar
8 votes
Accepted

Does a power supply wear out?

Essentially all electronics have a limited lifetime. The manufacturer specifies conditions for use of the electronics – for power supplies, these are, for example, input voltage (and frequency of AC ...
jwo's user avatar
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3 votes

Matching power supply to a four pin connector

You’ve got a supply with positive and negative and remote voltage sense capability. The connector has four pins, so you could either connect two pins to positive and two to negative to double the ...
GodJihyo's user avatar
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13 votes

Does a power supply wear out?

Yes, power supplies do wear out. For example LED lamps may start blinking or don't light up because their power supply is not working any more. Components such as electrolytic caps will degrade over ...
Justme's user avatar
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1 vote
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Usage of two PSU in parallel for WiFi router using Schottky diodes

What you measure is perfectly normal. While Schottky diodes have less forward voltage drop than a standard diode, they leak current in reverse much more than a standard diode, which is what you ...
Justme's user avatar
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1 vote

Do you know this circuit?

The 2 PNPs form a simple comparator; comparing the emitter voltages. When the 3V3 level is higher than ext_3V3, the right-hand PNP will have a higher VBE than the left-hand one (since the bases are ...
jp314's user avatar
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1 vote

Maximum power transfer with constant source power

Is this correct? No, the only time you can get maximum power transfer is when Rm=Rl (with AC you also need to include Lm which will change the current phasor) An infinite resistance (which would mean ...
Voltage Spike's user avatar
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1 vote
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Distribute power from one battery to multiple devices

All these components on that system, works in certain amount (range) of voltage, right? Right. how can I create a system - above the main system - to distribute power correctly Do not power the ...
Davide Andrea's user avatar
4 votes

What are these resistors used in this flyback converter?

The resistors power the IC initially, before switching start. (After switching starts, the IC is powered by the third winding, the one at the bottom.) Spec sheet
Davide Andrea's user avatar
0 votes

How to isolate RS485 (A and B) from existing transceiver? Check attached circuit diagram, is it correct?

This will be hard. You cannot know when either side has enabled transmitter and will soon transmit something on bus, you only see when something gets transmitted. Perhaps if you know about the ...
Justme's user avatar
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2 votes

How to isolate RS485 (A and B) from existing transceiver? Check attached circuit diagram, is it correct?

If I've understood your goal, you have a controller device which is half-duplex RS-485 (on the left), and a slave device, similar, on the right. The controller is not isolated, and you want it to be. ...
jonathanjo's user avatar
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0 votes
Accepted

Please help me identify this IC - top marking "APKZ LS23"?

It's an Intel EP53F8QI step-down converter. (Source: aliexpress.com)
nanash1's user avatar
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3 votes
Accepted

Power supply gives at most 20 millivolts

The PAB 250-0.25A has an input and an output fuse. Check the output fuse, it's a normal 1/4" x 1-1/4" type rated at 300mA. If it is open, replace it with the same type and rating.
Spehro Pefhany's user avatar
1 vote

error in stlink utility

You are not supposed to use pin 19, it is not a standard to have 3.3V output. And you need to use pin 1 to MCU VDD, or the ST-Link cannot communicate with the MCU. So you have basically swapped pin 19 ...
Justme's user avatar
  • 158k
3 votes

Is it possible to build consumer-ready, non-PC modular power supplies for generic external devices?

I'm not going to answer directly your question (I don't know such a product, but haven't searched for it either), but I will explain why, in my opinion, designing such a product seems complicated : ...
Sandro's user avatar
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1 vote
Accepted

Programmable pulsed current power supply

For currents of 100mA or so, at 1kHz or less, I don't think you need much more to make that Howland-like current source work well, using almost any op-amp: simulate this circuit – Schematic ...
Simon Fitch's user avatar
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0 votes
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Adding Resistor to Match Power Draw for Fan Replacement

Your calculations are correct: If you want to draw the difference in specified currents between the two fans (0.23 - 0.06 =) 0.17 A at 12 V then the resistor should be approximately 70 Ω. And it would ...
SamGibson's user avatar
  • 17.9k
1 vote

Programmable pulsed current power supply

Search for 'opamp current booster circuit' or 'opamp current booster schematic' (without quotes) to get dozens of examples, tutorials, and app notes. National Semiconductor (now part of Texas ...
AnalogKid's user avatar
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1 vote

Programmable pulsed current power supply

Made with microcap v12. If you want a "little" output voltage, something like this could be used ... Output transistors are allowed to ~ 10 W out. And here, the behavior with TIP120/TIP125 ...
Antonio51's user avatar
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1 vote

Connecting Two 24VDC Power Supplies

Having multiple supplies is possible, as long as you ensure common ground and avoid any cross-feed between the Supplies. Different question: Why not use a stronger supply to feed the whole circuit in ...
S_G's user avatar
  • 624
0 votes

Connecting Two 24VDC Power Supplies

It is better for you to connect both GND and make one reference GND. So you can avoid any noise in data logging part.
Nima Azad's user avatar
0 votes

Power supply for microcontroller

Microcontrollers are not like OP amps. They have a single power supply of 3.3 or 5V and a GND. Some MCUs have a maximum power supply tolerance of about 10%. Its better to consult the documentation of ...
Amit M's user avatar
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5 votes
Accepted

Power supply for microcontroller

No, because the ATMega328P MCU is not rated for 5V to 7V supply to begin with. It is rated for 5.5V max, and it does not have to work outside nominal range of 5.5V, and absolute max rating where it ...
Justme's user avatar
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2 votes

Can you help me understand W=I*V - house load

It says it's 150w, with 240v ac input and 2.5a. 2.5A * 240v = 600w - am I missing something? Several somethings, but the big one is that the ratings you find on the labels or nameplates of most ...
hobbs's user avatar
  • 7,637
1 vote

Does it matter if a fuse is on a positive or negative voltage?

One more try. Fuses will not work, but a TVS Diode will. A PSU will not generate enough fault current to operate a fuse promptly, if ever. The goal is to protect your device from overvoltages or ...
Dereck's user avatar
  • 652
0 votes

PCB inverter design

But how to design a PCB for an inverter or power converter without using separate power supplies for microcontrollers and gate drivers... designing only by using input supply Use is made of isolated ...
Andy aka's user avatar
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0 votes

How to protect a motherboard from an old power supply?

Use one of the TVS Diodes across each rail. Once it turns on, it will clamp the voltage or die trying. Select one large enough, like 5KVA, to blow up any PSU. It costs a buck or two on Mouser.
Dereck's user avatar
  • 652
1 vote

How to protect a motherboard from an old power supply?

A fuse at the output of a power supply, protects it from damage that could be caused by over-current or short-circuit. It definitely cannot protect the load (motherboard in this case). 'Crowbar ...
vu2nan's user avatar
  • 18.8k
0 votes

Does it matter if a fuse is on a positive or negative voltage?

Can I use a fuse 5V 0.5A for this -5V rail as if it was 5V 0.5A? Yes.
vu2nan's user avatar
  • 18.8k
8 votes

Does it matter if a fuse is on a positive or negative voltage?

The fuse does not care if it has + at one end or - (and the opposite). They do care about AC vs. DC because AC has less tendency to arc, but that is unimportant at 5V and not much more at 12V. You ...
Spehro Pefhany's user avatar
2 votes

Does it matter if a fuse is on a positive or negative voltage?

A glass fuse is a passive device; it is AC/DC and swings both ways. The question is, why would you do this? You are not protecting anything. An over-current protection device (OCPD) like a fuse can ...
Dereck's user avatar
  • 652
1 vote

Does it matter if a fuse is on a positive or negative voltage?

I have a power supply with +5 and -5 volts output. Can I use the same fuse for both of them rated 5v 2a? Is this a bipolar power supply with +5, 0, -5 V outputs? If so, you can use the same type of ...
Graham Nye's user avatar
  • 4,423
6 votes

Does it matter if a fuse is on a positive or negative voltage?

Yes. Fuses are non-polar. The fuse is a thermal device. It contains a material that melts at a relatively low temperature. The heat for the melting process comes from the current (energy) passing ...
DrFriedParts's user avatar
  • 12.7k
1 vote

Does it matter if a fuse is on a positive or negative voltage?

Fuses do not care about conventional agreements of people regarding positive or negative voltage.
Stefan Wyss's user avatar
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1 vote
Accepted

Is a smoothing capacitor only useful when the trace has impedance

Smoothing capacitors are only useful if the trace has enough impedance to cause a voltage drop at the load, and only really for switching loads. If there is too much inductance in the trace/conductor ...
Voltage Spike's user avatar
  • 84.6k
1 vote

does rf remote transmitter power affect solenoid strength

No. The RF receiver portion of the device will simply supply a logic 1 or 0 to the circuitry controlling the solenoid. Increasing the transmitter power will only increase its range (and is illegal in ...
1 vote

Help me to identify SMD diodes marked '1DN'

The markings and package seem to match with a CITC B1DWGL-SN rectifier diode. The package is SOD-123S which seems about right from the picture.
nanash1's user avatar
  • 5,872
2 votes

Help me to identify an SMD component marked 'NM' in an SOT-89 package

I think @Tony is correct, the photos match lcsc's listing for the 2SCR533P5T100 and 2SCR533PT100. The latter is NRND and the difference between the two appears to be grade related- the electrical and ...
Spehro Pefhany's user avatar
1 vote

Does it improve safety to make a capacitative dropper symmetric?

I'd say it makes even more unsafe for variety of reasons. First of all, let's assume you live in a country where mains sockets and plugs are polarized and always wired correctly and there is never any ...
Justme's user avatar
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2 votes

Powering on a laser diode that exceeds PSU max current

To make a quick test of that power laser diode, put a small resistor in series, and a moderate size capacitor across the output of the power supply. In the diagram above, a 1µF cap charged to 10 or ...
DrMoishe Pippik's user avatar
0 votes

Does it improve safety to make a capacitative dropper symmetric?

If you use a circuit like this, then every node, before and after BR1, must be isolated from the possibility of touching it. Once that is done, it doesn't matter whether the capacitor is in the live ...
Neil_UK's user avatar
  • 169k
1 vote

What's the role of the transistor on power input in this schematic?

Q1 is a P-channel MOSFET that is normally used in this configuration as a form of reverse polarity protection (for example, if you reverse the cable connection on P1) that is more efficient than a ...
Ronan Paixão's user avatar
4 votes

Powering on a laser diode that exceeds PSU max current

Edit: See also comment by DrMoishe Pippik If pulsed operation is fine (as it is here), you can get away with a capacitor, inductor, Power MOSFET and a signal generator. The idea is to convert the 10A ...
AnttiP's user avatar
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4 votes
Accepted

How is it possible to supply an LM833D with +12V and -8V supply?

Think carefully: how can the op-amp tell that the supply is anything but 20V? As long as the inputs are within the allowed input voltage range, and the output is within the allowed output range, the ...
Kuba hasn't forgotten Monica's user avatar
6 votes

How is it possible to supply an LM833D with +12V and -8V supply?

Why shouldn't it be possible? The Op'amp only cares about the voltage between it's 2 supply pins (and that the voltages at input and outputs pins are within the allowed limits compared to the supply ...
Sandro's user avatar
  • 7,697
0 votes
Accepted

ADC pin protection when using external power supply

It's very unlikely that a spike on the ADC pin caused damage. The resistor and internal clamp diodes limit any excessive voltage to the supply voltage. If you are using the same power supply to power ...
Saadat's user avatar
  • 1,831
1 vote

What's the role of the transistor on power input in this schematic?

Q1 is a P-Channel Enhancement MOSFET is open in case your vgs is positive. In this case, you can ensure VIN > GND and protect the circuit from reverse connections.
Jessay's user avatar
  • 21
5 votes
Accepted

What's the role of the transistor on power input in this schematic?

It's to protect against an accidental reversed power connection. Normally, when VIN > Q1_threshold, Q1 will turn on and supply VIN to then'5V' line. Q1 will just act like a negligible resistance. ...
jp314's user avatar
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