New answers tagged

1

Usually an unused comparator (like U6B) is connected thusly to keep it's output stable. If left unconnected or tied to the same rail internal noise could make it switch states randomly and perhaps quickly. However it really shouldn't be necessary as the comparator is open drain. Just leaving R22 open should give the same effect. Biasing the inputs like that ...


1

Hook up a current probe on the AC line, and look at the AC voltage and current simultaneously. If they're the same shape, then the supply has PFC (or, at least, doesn't inject harmonics of the voltage into the current).


6

You measured the loudspeakers' DC resistance at 12 ohms each, which means they're "16 ohms" speakers. Note the speakers' impedance varies with frequency, it includes an inductive part and reactive parts due to mechanical resonances, cabinet, etc. So, it is normal you don't get 16 ohms on your multimeter for a "16 ohms" speaker. Here's a "8 ohms" speaker ...


0

Found someone with the exact same issue here EEVBlog Caps suggested RS 871-2748 CPC MAL205858472E3 I would still be interested if anyone has comments about how to determine the specs for a replacement


0

Your question is over 1 year old, so you most likely have a solution already. If not, here is my advice:


2

"Best guesstimate" is that the 12V regulator is being overloaded. You do not tell us What Vin is for the +12V regulator What heatsink you are using on the 12V regulator Bonus unknown: Heatsinking on +5V regulator. The 5V regulator with 12V in dissipates (12-5) = 7 mW/mA. So at 140 mA power dissipation is 7 mW x 140 mA = 980 mW (if Vin remains at 12V). IF ...


4

China is similar to most of the EU. Phase-to-phase voltage for 3-phase is 380V 50Hz; Phase-to-neutral is 220V. Wye (4 conductor) and delta (three conductor) are supported; for a residence it would always include a neutral. The standard single-phase wall plug has one 220V hot and a neutral, and optionally a safety ground.


0

I can personally¹ suggest the LTC3637 if you want to build a circuit yourself. The quiescent current is 12µA (so pretty low), and has some nice additional features like current limiting, if you happen to require it. But keep in mind that both the TI and LT chips require that you design a PCB around them, you can't really solder it on a prototype board. So ...


0

In most DCDC converters there will be a feedback loop that controls the output voltage. Your design has such a loop as well, R9 and R10 are a voltage divider and the output of this voltage divider feeds back into the FB pin which compares the DC voltage on FB to an internal reference voltage (see the block diagram on page 16 of the datasheet). In a ...


3

The high frequency switching used in the SMPS can inflict some quite considerable high frequency common-mode noise on the DC output. This is due to the interwinding capacitance of the internal isolation transformer (aka flyback transformer). To reduce this noise (and obtain EMC approval) requires that the DC output is either grounded or capacitively ...


0

This is due to inrush current. To get a good feel for what you are actually dealing with a simulation is always a good help! (LTspice is worth looking into) As you can in the simulation the capacitor takes in (approximately...) 20 A peak at 24 V. To limit a high rate of change in current, an inductor can be used. But this will induce voltage oscillations ...


0

What if your 24VDC power wires had significant inductance causing a voltage spike of almost 48V at turn on When C7 has zero initial volts .This is why it was accepted old school practice to use 60 Volt parts for good reliability .Now that you have committed to the 32 Volt chip you must adress the peak volts across C7 by whatever means.


3

Measure the cold resistance of the bulbs. You’ll find that it is much lower than the wattage would imply. Incandescent filaments have a much lower cold resistance that increases as they warm up. This means that your 4.6 amp bulb will probably draw well over 10 amps at startup. Your power supply can probably supply additional surge amperage at startup but not ...


0

You are correct that the negative inductance is just a result of the modeling, it is a correct result. The only place i have ever seen an impact (other than computer modeling problems which are just numerical integration problems) of the negative inductance is in regards to polarizing of earth fault relays in power system protective relaying. Specifically, ...


2

It can't because 130 W is how much the adapter can supply not how much it consume. Your car's plug only supply 1.35 A 110v but adapter needs 1.8 A (198 W ) .


1

Strictly from an engineering standpoint, you have an outlet that says it can supply up to 150 watts, and a load that claims to only need 130 watts. So, it may work. There's all sorts of caveats (like, the power supply may take some inrush current above what the outlet can supply), but unless someone's been messing with your car electrical system it's ...


3

The 5V tolerant means you can use pull-ups in the open drain configuration, and doesn't work with push pull. This means you could possibly use a pull up to 5V and open drain, keep in mind that this method can be slower if you have too much capacitance on the digital line, the RC time constant will need to be calculated. This means if you remove the buffer, ...


0

From my understanding, the 5V tolerant domain is generated by an internal charge pump which runs from the internal regulator (presumably). So I'm not sure how what will happen if you drive a pin with 5 V if the device is unpowered otherwise. One could argue with the absolute maximum ratings table: the input voltage specification for a FT pin (five Volt ...


0

Is this an assignment? ZD1 "triggers" Q1 when V_zd1 + Vgate_Q1_trigger equal the desired trigger voltage - here about 6V. So Vzd1 needs to be about Vtrigger - Vgate_Q1_trigger Q1 needs to be an SCR rated at usefully above Vin_max (here 30V) and able to smile at Ioverload (here 5A) C1 is meant to deal with the odd voltage spike - OK as is - somewhat ...


0

You can measure the rpm with a tachometer, the cpm is the same as the rpm. And what noise is it you are looking for ? physical noise or electrical noise. The physical you can just measure, with your phone.


0

Connecting motors in series probably won't work anyway, because current draw is proportional to torque load so whichever one has the least load will hog the voltage. Also the same power is still required so it won't change the size of power supply required. Next problem is that though the motors might draw 4-6A each while running, at startup they may try to ...


0

Quick answer: You need to connect two wires to the (+) side of your power supply, and two wires to the (-) side. If your physical supply has an output cable with only one pair of wires, you'll need to splice the wires together somehow. Connect all the (+) wires together in one group, and the (-) wires in another group. There are lots of ways to do this. ...


0

I think there are some wires coming from the photocell that get attached to the power supply, and some wires go from the power supply to the relay. It sounds like there are black, white, and red wires already connected to the photocell...the black goes to the + side of the 12V supply, the white goes to the - side of the 12V supply, and the red wire is the ...


7

Look into the Bourns SRF1260 datasheet: Multiple applications: parallel, series, dual-inductor and transformer. Clearly the designer opted for parallel connection, thus doubling the current rating.


13

It's a "power" inductor because it needs to carry a significant amount of DC current. Connecting the windings in parallel gives you the same inductance as either winding alone, but with twice the current capacity and half the DC resistance. It's exactly equivalent to a simple coil with the same number of turns, but twice the cross-sectional area of the wire.


10

Unless the designer is here, there is no way to really know for certain. Perhaps it was a cheaper option. Maybe it had the best performance under tests conditions compared with other inductors? If the company that designed this already use that component in another design, it makes sense to re-use it on another product. It saves having to buy a new ...


4

I am using a 6V 6W solar panel with the Particle Boron microcontroller with a battery pack. I want to ensure that the voltage supplied by the solar panel does not surpass 6.2V, as that is the max Vin rating for the microntroller. What is a good and simple way to go about this without sacrificing too much power from the solar panel? The question suffers from ...


6

Such a slow decrease allows many possibilities for the MCU to "go nuts" and corrupt the EEPROM. It has enough supply voltage to do bad things (like write to EEPROM), but not enough supply voltage to operate reliably. The same thing could happen with a relatively fast decrease, just less often, so you may be lucky to have caught it before it caused field ...


5

The simplest is a shunt voltage clamp. The power from the panel is free, the panel is a high impedance output, and the power is low enough for a reasonable sized heatsink on the clamp to do the job. That way you lose no power at all while the output voltage is below the clamp voltage. Use a TL431 (or TLV431 the low voltage version) as the voltage sensor to ...


1

You have already described linear power supplies transformers rectifiers and smoothing capacitors, then you are half way there. A switch mode power rectifies the mains to give a high DC voltage. This voltage is then "switched" or converted back to AC at a high frequency. The high frequency AC is reduced in voltage using a transformer and this low voltage AC ...


1

Short answer: if you can't explain inductors to your grandmother, then you cannot explain switching power supplies. Can you explain resistors? Capacitors? Yes? Well, first you have to "own inductors," and understand them as totally as you understand resistors, but without math and without lingo. Most people understand resistors, but less about ...


4

The stuff you see around the capacitors is an epoxy potting compound to keep them from making noise while the PSU is operating (it’s on the filter toroid too, for the same reason.) When big electrolytics fail, they vent out the top. There is an ‘X’ scored in the top to allow them to vent if that happens. This would be super-obvious (and smelly) if that ...


5

That tan colored buildup is a 'hot glue' and for hotter temps than regular hot glue. You can also see the glue holding down the inductor. Usually capacitors will exhibit corrosion or a bulge when defective, it usually comes out from the top or bottom on electrolytic capacitors. The capacitors look fine from the pics shown above. Here is what a bad cap ...


1

The basic-basics: input -> magic -> output, except the magic part doesn't violate the laws of thermodynamics, so power out = power in * efficiency. Meaning you can't get 10 watts out with one watt in, for example. It explains why a boost converter generates high voltage/low current on an output with low voltage/high current on the input, it explains why a ...


3

I'd recommend trying to describe a simpler circuit than the one you posted in your question. A buck converter is a much simpler SMPS. It is also DC-DC, so you don't need to worry about AC rectification: (source: Wikipedia) In a buck converter, the output voltage is less than the input voltage. I might describe it this way: This type of SMPS works by ...


0

The short answer is, break it into smaller pieces, show how each one works, then tie them together as a system and show how they interact. Have a look at this video as an example of a simple, but thorough walk-through of a switch mode power supply. https://www.youtube.com/watch?v=KIilQrgJ-gg (Bonus: Commie test gear, and a cat.)


0

Well, it is an odd way of saying it needs 5V DC in the datasheet, but that seems to be what they mean based on the picture of the device itself. The connector is standardized, yes, and it is called a "DC barrel jack", or some variation of that. There is different sizes of the DC jack available, measured in inside diameter, outside diameter and length of the ...


0

It needs 5V 1A power supply. It does not say what connector and polarity. Officially HDMI sink devices may not consume more than 10mA (50mA when turned off) and sources must limit current to 500mA, so this HDMI switch violates the specs in many ways and simply can't work properly without external power supply.


0

Well, here’s a simple way: use a 10A PTC resettable fuse. Like these: https://m.littelfuse.com/~/media/electronics/datasheets/resettable_ptcs/littelfuse_ptc_radial_leaded_ruef_datasheet.pdf.pdf


1

In a general way, the earth is connected to a metal plate buried near the point of usage (in your garden for example). It is used to protect yourself from electrocution by connecting all metal plates of your device to the earth, this way, during an electrical short-circuit the current will "prefer" return to the earth through the cable than going to the ...


8

No, do not connect neutral to earth or digital ground. In some parts of the world the mains plugs are not polarized so there is a 50% chance it ends up connecting live to earth or digital ground.


2

It may depend where you are, but in the UK neutral and earth must not be connected together downstream of the supplier's intake. Joining N-E would trip any Residual Current Device (USA: GFCI) A surge protector circuit might be connected across L and E but this should not pass appreciable current under normal circumstances. The amount of residuial current ...


0

The first datasheet you refer to is the consumer of the power. The device will have another regulator on the board to regulate the voltage into required level. This is same as regulating a external supply from a wall adapter (probably alternate supply Input, not mandatory) . The second link is the power injector which has the capability to add the Power ...


0

Okay so for anyone looking for an answer for this question, finally i was able to put everthing in the right way . The solution : I have inserted the stick into port 2 (i monitor) and the other part in the left nail. you will get the clear picture by looking in the below figure. After that i started a test to make the devices work to be able to measure it ...


1

usb-c pd afaik has some IC on both ends that do the charging logic. without it I fear you might just fry whatever you attach to it..... easier to just get a solar panel with the usb-c pd ic integrated. Like: https://www.amazon.com/dp/B07SW3GZ64/ref=psdc_2407761011_t2_B0785WCZG7?th=1 or https://lifepowr.co/shop/sun20c/


1

If your lab power supply offers the needed voltage range for each lane (positive and negative), this is easily possible. Disconnect your former power supply (transformer + bridge rectifier). Select +41V on both power supplies (nominal supply voltage for your TDA8954, might differ in your application) connect the outputs of your power supply in serial, tap ...


1

simulate this circuit – Schematic created using CircuitLab Figure 1. The DC supplies can be connected in as shown by V1 and V2. You can leave everything else connected but disable the transformer AC supply so that nobody can reverse power V1 and V2 as they may not like it. Note that V1 and V2 need to be isolated and can't, for example, have both ...


1

Anything touching the power transformer primary side (line cord, connectors, switches, fuses, etc.; and of course the transformer itself) should be UL listed. Any conductive surface that might come in contact with the user must be double-insulated. There are spacing rules regarding how close together conductors can be, and there are similar rules for the ...


0

You're right to be confused; 5V at 900mA is only 4.5W. The specifications given are probably simply wrong. But it's hard to say for sure which parts of the specs are erroneous. This is part of the reason why on EE.SE we like to say "No datasheet? No sale!"; With a proper datasheet, you have much more information at a higher reliability. Even if the ...


1

At its core, a USB power adapter or "wall wart" is a 5 V power supply. They usually have a universal input able to handle AC power line voltages from 90 to 240 Vac (-ish), and an output current of at least 1 A. All USB warts are switching supplies, but there is no reason to stick to that for a home project. But An AC-to-DC power converter of any kind is ...


Top 50 recent answers are included