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Background (with a little speculation) Inside the TV's switch mode power supply will be one or several Y capacitors that connect the internally produced DC voltages to either live or neutral. They are there to reduce the common mode noise produced by the high frequency switching transformer from affecting the DC outputs. Without the Y capacitors, all the ...


8

The one on the right is an older Samsung Adaptive Fast Charger. It communicates on the data pins to allow for the faster 9V charging voltage. Its a proprietary Samsung protocol. The one on the left is a newer USB C with Power Delivery standard (PD) 3.0 (or newer) with PD 2.0 PDO charging (fixed profiles) and PD 3.0 PPS charging (arbitrary voltages in a range)...


4

The best way to turn a motor with a speed controller on and off repeatedly is to use the controller to do that. A good controller should have an electronic start/start input. If the controller doesn't have that, see if you can command zero speed. It is not the best practice to repeatedly disconnect either the power input to the controller or the power output ...


3

Prior to the invention of the transistor, DC motors were started by putting a resistor or several in series with the motor and then shorting them out either manually or with timed relays. The diagram below shows a manual starter for a DC motor. The resistors connected in series with the armature of the DC motor are progressively bypassed by manually moving a ...


3

The optocoupler 1st-order model is a simple current-controlled current source whose output is decoupled by a parasitic capacitor. This is what has been represented in the post. This capacitance needs to be characterized and accounted for when adopting the compensation strategy. The below circuit shows how to extract this parasitic element. More details can ...


3

The recommendation given in the application note is not new and the phenomenon well known. A capacitor is made of several parasitics among which you find the equivalent series resistance (ESR): This ESR can be revealed by an impedance graph or be extracted from the capacitor data-sheet. For an electrolytic capacitor, the ESR varies significantly with age, ...


2

What you need is a variable duty cycle, which is part of the control loop. If you have that but don't know how to implement the PWM part, here's a start: If you don't have the control loop, then you'll have to build one: voltage mode, current mode, karma mode, etc.


2

TL;DR ( get an 8 Ohm @ 25'C, not the hot R " @ current ", Inrush Current Limiters ICL from D-K) These come like radial ceramic caps or in SMT format. (TL;DR is the modern vernacular for Too Long {and lazy}; Didn't Read) These are Metal Oxide NTC's (Neg. TempCo's) that have the opposite thermal characteristics of PTC's used for soft current ...


2

You can use a power supply which restricts output current but doesn't shut it off. Even in that case the power supply should provide enough current to create torque. The start current is just voltage divided by active resistance, measured with ohmmeter. In your case the motor has a gear drive as a load, so the start current should be bigger - 5 amperes is ...


2

It does not work with such low voltages. It even has an under-voltage lockout to specifically prevent that, so it requires more than 4.5V to start. While some regulators have that feature, this regulator is not built to pass input to output. There is a NMOS doing the high side switching and it cannot turn on unless the gate voltage is made by switching and ...


2

The inductance is way too high compared to suggested values. Refer to Fig.32 at p.17. A 22uH inductor is fine, but you placed 470uH. I know, the values suggested are given as "minimum", but remember that increasing the inductance is not always the preferred way. A very large inductor may result in unexpected behavior. I'll answer only the 1st ...


2

That is a long shot, but the high ripple voltage you are seeing is because of the electrolytic capacitor \$C_4\$ you picked. According to the its datasheet it has an \$ESR=160m\Omega @ 100kHz\$ The capacitor used in the reference design is a tantalum one, with an equivalent \$ESR=18m\Omega @ 100kHz\$ Although you are switching at a lower frequency (\$\...


1

Why couldn't I employ these toroids in a half bridge or push-pull topology as opposed to the E cores in the photo? Three reasons that spring to mind: - It's a lot easier to manually wind turns onto a bobbin then add that bobbin to the cores compared to manually winding a transformer on a toroid. With core-sets, you can apply gapping to give you superior ...


1

As a working example, the ATX PSU spec gives a hold-up time of 17ms, which corresponds to one 60Hz cycle. Any other supply you will need to check on this, but it's likely to be similar to ATX. So an instant electronic switch could work - there will never be a case of a full-cycle dropout regardless of the inverter vs. line phase. Could a mechanical switch do ...


1

You will need enough input capacitance, and It also depents on the load. You can try to calculate It but I Think it's easier to Just try it out. However I would not reccomend using handswitch, because it May be possible to vary switching time a lot. Instead Relay + latching circuit can be used. Ac to dc smps works like this: rectyficate Input 50Hz to dc (...


1

The main purpose is to measure the input current (i.e. the current drawn from the source). T101 is a current transformer. When the input current (a switching current) flows through T101's primary, a non-zero current proportional to the input current (and, in-phase of course - look at the dots) flows through the secondary: $$ n=\frac{N_p}{N_s}=\frac{V_p}{V_s}\...


1

The capacitance and ESR forms an RC lowpass filter. If the ESR changes by tenfold, then the cutoff frequency of RC will too, so it changes the filtering frequency. Which leads us to 2) It requires that the regulator, or the external compensation circuitry it has, is designed to allow for this variation in the ESR and the variation in the lowpass frequency ...


1

As I stated in the comments, a little background of Control Theory is required to fully understand. This document from On Semi could be a good start. That's because of the self-resonance of the capacitor. An ideal capacitor has only a capacitive part, but a real capacitor is nothing different from an RLC circuit. Looking at the Z-f graph of a capacitor, you'...


1

The control circuitry is internal to the IC; on page 12 of the spec it's in the lower and center left of the block diagram. It takes the feedback signal and uses it to adjust the switching frequency or duty cycle, depending on the chip. It may also introduce other control or filtering techniques. The loop can be considered a sampled system at the switching ...


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