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0

I see this as a “mechanical” problem often faced by EE’s , that being the ambient noise of high velocity fans with Eddy current acoustic noise on the safety grids. Techie details But being EE’s we are much more familiar with Eddy current noise than ME’s. what you want is a longish laminar plenum tube (square or round) air exit and remove the safety grid ...


0

The voltage will drop at a rate of dV/dt = Ic/C and if current is limited by 1k then Ic (max) =V/R where a power interruption or switch to battery becomes worst case dV=V so the time constant for 64% voltage sag = RC=Tau = 10ms so a 1ms interruption is only 6% and less for a FET bridge. Also any ripple > 1/RCf is attenuated by 20 dB/decade in f, which may ...


1

Section 14.1 of the datasheet tells you why - the supply is monitored to allow it to switch over to the backup battery if and when it fails, and needs to not fall by more than a specified rate, such that the monitor circuit has time to make the switch over before power is lost.


0

Your Bridge rectified 3 phase DC bus volts will be around 500 VDC .This is too much for an isolated flyback SMPS using orthodox parts .Some countries use 480 VAC meaning even higher DC bus voltages .A two transister Flyback will be reliable if 1200V switching devices are used .Efficiency wont be brilliant but it will cope with wide mains variations .


1

Look into a multiwinding flyback converter. That is likely to be least cost option. You should further consider isolation voltage requirements, isolation capacitance requirement, and required power ratings also.


1

The circuit is easier to understand if it is redrawn so that voltages increase strictly from bottom to top. I've drawn the rectifier as a floating voltage source for simplicity. Since ground is defined as the point between the two output capacitors, then D15 establishes the most negative voltage as -13V. D14 then puts the ADJ pin of the regulator at +12V, ...


1

For consumer use, it is not popular, for light industry it is not common, but for heavy industry (MVA generation) as long as somewhere in the system design there is isolation and safety earth ground, there is no restriction for isolation if no service access is needed or safety hazard imposed in use. You are likely never to see the latter unless you are ...


0

As you calculated correctly, the 1.5kohm resistor will dissipate 0.384W if there is 24V across it. So, about 10% of its rated power. Will it be damaged? Not at room temperature, however, at higher ambient temperature you should check the power deration curves. E.g. the SMW520RJT made be TE connectivity, a 20 ohm, 5W resistor, has the following ...


5

Like Aaron said, a topology with a transformer allows for better control of the step down/step up voltage. A duty cycle of 7% seems fine on paper, but in reality you should aim for closer to 30%. In an application with changing load that 7% nominal duty cycle can drop down to 1 or 2% with low or no load. When using a PFC, especially a boost PFC, the 400V(...


4

With a simple buck converter, you only have one degree of freedom, the duty cycle. And as you are noticing, the duty cycles for those input:output ratios are very small. With a transformer design like a flyback, you get two degrees of freedom, the duty cycle and the transformer winding ratio. Usually you design the winding ratio so that you can be in the ...


0

There are different kinds of generators. Some do supply constant electricity with monthly schedules like nuclear and thermal power plant, these can't dynamically change the production. The variable part of the demand is supplied by power plants that can quickly turn on and off, these are gas turbine, hydroelectric plant, diesel. In case of increased demand,...


2

Power line transient is also a major fuse blower with Z1 OVP protection. The 3 phase bridge produces 6f frequency ripple which is used to drive the FET as a BUCK regulator with Zeners to limit Gate drive, LDO input max and forward current to power tthe load. Given the LDO operates at 1.25 between Vout and Vadj, with a short circuit between these the ...


0

PWM may cause current measurement errors and long wires can introduce inductive voltage/current errors. I suggest you use a TO-220 transistor so it doesn’t get hot, and bias the base current with a Voltage control Rseries or a pot and series R to limit the base drive, in order to dim the LEDs . A voltage divider to 0.4V will turn off the transistor ...


2

Figure 1. LED I-V curves. According to my Figure 1 a typical white LED could be expected to drop about 3.5 V at 37 mA. Four in series would drop 14 V which is in pretty close agreement with your 13.6 V measurement. Accurate figures for low currents aren't often published but if my graph is any way accurate you should see a voltage drop of about 1.5 V at 1 ...


1

Assuming the voltage drop of the zeners are the exact voltage drop, then. with respect to GND (text between C3 and C4) D15 subtracts 13V, D8 adds 43V and D7 subtracts 10V again, leaving 0-13+43-10 = 20V


1

I really want to understand is how the +27V is generated... R1 and D8 are a simple zener regulator to 43v. Then D7 subtracts another 10v off of that for about 33V. 20% isn't out of the realm of tolerances for zeners. I'm betting that the 27v varies depending on what is going on. It's just a pre-regulator to the LM317. and how the FET is turned on D1-...


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Who would cover the electricity difference if the generator does not end up producing the quantity stated in the trade or where would the overproduced electricity go, if the consumer has estimated his consumption poorly? This is why continuous grid management is needed. Electricity in the grid in most cases cannot be stored for later use. It is a ...


0

The simple answer to "where would the overproduced electricity go" is that the generator will not produce excess electricity and that causes a reduction in the fuel that feeds the driver of the generator. It is more complex than that. Some types and sizes of generating equipment are easier to "throttle back" than others. Suppliers or groups of suppliers have ...


1

where would the overproduced electricity go, if the consumer has estimated his consumption poorly? It doesn't go anywhere - if the consumer under-consumes compared to the original prediction then, that under-consumption is physically less-current being taken and less-power being supplied by the generator. Electricity isn't like a delivery van setting ...


0

Question: Does this modification disable safety features? NO. Not if done exactly as stated. It enables a status resistor loop to enable the supply and only removes the secondary earth bond and not the primary AC safety ground to enable series DC connection of 12+12=24V @ 75A (850W at 120Vac, 1200W out at 230Vac rating high efficiency) making the two ...


1

Although computer cooling fans draw low current, you can not feed them directly with Arduino. Typically, you need a buck or buck-boost converter that can be controlled by Arduino to change the input voltage of the cooling fans. But, you can simply use a ULN2803 L293, or L298 to control the fans by PWM. The speed of the fans is controlled by the duty cycle of ...


1

I think sstobbe is on the right track here - something in the supply likely has a “sneak path” to the chassis. I would start troubleshooting this by connecting a high value resistor (100 k perhaps) between the minus output and the chassis ground. That shouldn’t make the supply turn off and you can measure the voltage across the resistance- check for both AC ...


2

There may be problems if you have unpowered peripheral devices connected to a powered microcontroller. You need to make sure that all microcontroller pins that are connected to these peripherals are set to a low voltage (logic 0) before removing power to the peripherals. Otherwise, significant current will flow through the input protection circuits of the ...


1

This diagram is incomplete as it is missing bypass capacitors. Typically they would be 100 nF to 10 uF. The 1K resistor limits charge current to just 12 mA max, much less if battery is close to full charge. This would be an unregulated 'trickle' charger. The diodes are used for reverse polarity protection.


3

The two diodes (D2 & D3) work to OR the voltages, the idea being your 12V_IN will be slightly higher than 12V_BATTERY, so current will flow from 12V_IN to power the device when its present... Minus a diode drop. When 12V_IN is removed current will flow from 12V_BATTERY through D3 R1 is probably there to act as a current limiting resistor for charging ...


1

Below is the final design based on iput from responders:


2

We've designed piezo drivers for many years. The piezos are typically driven with a triangular or sine wave for use with interferometer alignment. If this old post is still of interest I can try to have a schematic reduced to a B size.


4

Depending on the supplies, cabling etc. it's quite possible that adding diodes to the USB 5V supply may well reduce the voltage enough to put it out of spec. And you don't need them anyway if J1 is always present as J3 has its own source of power. Hence:


4

Do I need both diodes D1 and D2? Or Just D2? Even if D1 might not be necessary, I would retain both for protection of each individual circuit (If the device can tolerate the voltage drop caused by the diode). I, personally, would want D2 to ensure protection to my computer USB port. Furthremore, since J1 will power the microcontroller continously and J3 ...


-1

I returned this power supply and purchased another 10A12V power supply. It is able to supply 10A as expected.


1

A related question: Is a typical 120v wall outlet not truly sinusoidal either due to noise / harmonics / etc? Typical wall outlets do have harmonics, and this is mostly dependent on the quality of the grid and other loads near whatever the device is plugged into. Harmonics are not usually an issue, devices with a rectifier and then a filter probably ...


1

Yes. Increasing the load on your battery, either by adding more fans and pumps or replacing the existing fans/pumps with fans/pumps that require more current, will lower the voltage available to all of these devices, including the cooler module. The reason is that your battery is not an ideal voltage source, so as the load current increases the terminal ...


2

This is what I get out of the setup you envision: SMPS -> VReg* -> SMPS And your asking about the rail with the * on it. In this case, the last SMPS will affect the regulation of the Vreg because it is switching current and because the Vreg has source impedance, and cannot respond infinitely fast to regulate the voltage. The question then becomes, how ...


0

Strange but using RCD clamp instead of Zener Clamp solved the issue for me.


3

Because lab supplies will actually be tested by people with unpredictable loads and high-quality measurement equipment. Thus, the quality of voltage stability and accuracy needs to be significantly higher for lab supplies. Do a test: get a 2 Ω power resistor and attach it to your notebook supply to draw ca. 10 A; measure the voltage with that load, and ...


2

"is your PC properly grounded"? I would say that your problem is that your equipment is "too much grounded". Likely you have several ground loops that create ground spikes as you turn on-off other equipment, through so-called "ground bounces". Try to power your PC and CNC from the same power strip (even is you need a long power cable to your CNC, and don't ...


2

L1 reduces the noise generated by the converter. If too much electrical noise gets into the mains cord the product will fail EMC. L1 is far too small to reduce mains frequency artifacts. If L1 had enough inductance to attenuate mains frequency harmonic noise, the small cheap SMPS could double in size. Passive mains harmonic filtering is not cheap and when ...


0

Automotove alternators almost all have a regulator that varies the current through the wound field coil in the rotor, producing enough excitation in the stator to generate the required voltage for the system. Once the battery is fully charged, the field current drops to the point that the alternator is only producing enough output to address the remaining ...


1

If you are powering your modules over a fairly long wire, when the relay actuates there will be an additional voltage drop across the power feed wires. Therefore I suggest you generate the required 5V locally at each module derived from a raw 9V supply derived from the Arduino. A search of Ebay, Banggood or possibly Alibaba should turn up some suitable cheap ...


1

You need to be looking at the trip curves for MCBs when planning for inrush: https://studyelectrical.com/2014/07/miniature-circuit-breakers-mcb-types-characteristic-curves.html#Selection_of_Right_MCB You can see that 10ms and below is not on the graph. Inrushes below 10ms will not cause a trip, by design. From having designed similar equipment I would ...


1

Multimeters measure resistance by applying a known voltage across and measuring the current, or vice versa, a known current being applied and measuring the voltage. You can't measure devices that are on this way because the voltage of the device is almost always higher than the voltage being applied, overriding it. On top of that semiconductors can have ...


1

More twisting means more contact surface betwen magnetic radiofrequencies polarities which can be assumed as less output voltage as the twisting decreases conductance ratio developing a closed magnetic field which converges to more inductance. eventually showing a predictable extra current than driving a bare load with no twisting at all... Interestingly the ...


2

I simply used a $3 freq generator (aliexpress.com) and a N-FET, connected one phase to 12V, the other to drain, and source to ground. Very simple. There is two issues, no self starting (I set to 60Hz and give it a light spin), and there is a acceleration limit, you cant go to quick or it loses sync. Quick testing showed 1000Hz freq was no problem (about 6W ...


0

You might want to have a look at IEEE Std 315, "Graphic Symbols for Electrical and Electronics Diagrams". Of course, this is a U.S. standard and other countries may have their own standards.


2

You can't measure resistance between VCC and GND when power supply drives voltage between VCC and GND. The multimeter is confused because there is an external voltage source. Also, measuring resistance of anything that is not a resistor will give weird readings, as they can have nonlinear behaviour like LEDs or semiconductors. At most you can measure if ...


1

What could be causing this? When the board is off this is a little unusual because most often the leakage current through transistors or loads when the power is off is in the 1-100kΩ range for most of the boards I have with voltage regulators on them. If you had something with a high side switch or a relay this could explain why the numbers are so high. ...


3

There are really two parts to this question. Will it work without risking damage to IC2B Will it function properly. The voltage at both inputs will be within the power supply range so the +/-32V absolute maximum rating is easily satisfied, so it is not close to damage from differential input voltage. There is another constraint- input voltage must be ...


0

Is it only a motherboard ? could explain why you want to do that to a desktop instead of just using a laptop. Since you want to get rid of the AC part , the motherboard run off DC voltage (12V max) (-12V min) ATX PIN Layout ATX pin layout reference Instead of taking the route of inverting Low DC to High DC and back just to supply a PSU , you ...


4

This is certainly possible. There are DC/DC converters made exactly for this purpose. You might want to google for "dc/dc atx power supply 12v". These converters are available at different power ratings. Many of them are designed for carputers (computers in cars). In the picture you see a small one providing 80 W power. It is mounted as part of the ATX main ...


0

First, lets check the feasibility. I put a power meter on my new desktop computer. It is a large tower, but it isn't loaded up with cards. The OS is running on a SSD, this helps keep the power down. It also has a traditional HD. The power varies between 23 and 110 watts. The average is probably about 40 W when doing a mixture of realistic tasks. My large ...


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