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35

No. A linear regulator works by burning off excess voltage as heat, therefore current in equals current out. The linear regulator is essentially throwing away the excess energy in order to regulate, rather than converting it to the output. You need a switching regulator if you want to take advantage of power in equals power out in order to convert a high ...


32

You can get 8 kV rated (at several thousand amps) thyristors for use in HVDC converters. The gate is optically coupled for the obvious reasons and also because, when used in tandem on HVDC links, the gate driving speed differences between series connected thyristors is important and optical is a little bit more clear cut speed-wise: - Stack a few together ...


28

RL1 is a relay, a type of electrically-actuated mechanical switch. The swirls are the relay's coil, and the two lines indicate that it's wrapped around a magnetic core. The thing labelled N/O and N/C is also part of the relay; N/O is "normally open", which means that switch contact is open, or disconnected, when the relay coil is not energized. N/C likewise ...


25

You can pick anything you want and call it ground. This power supply box has two power supplies in it. Shorting the + of one to the - of the other puts the two power supplies in series. That gives you a so-called "split" power supply. You can call the middle connection ground and then you have +15V, 0V and -15V wires. Or you can call the right connection ...


25

Negative on the outside of the barrel connector, positive on the inside of the barrel connector. It is the standard method of showing the polarisation of the barrel connector. The positive pin is usually (as in this case) the inner contact, and negative is usually the outside of the barrel. If you look at the image, it shows a surrounding area labelled "-",...


24

This is neither Kosher nor Halal. It should actually be explicitly forbidden in the Electrical Engineering code of ethics. Some certification standards explicitly frown upon this. Besides the wires probably being extremely under-dimensioned for the delivery of power, using narrowly-defined standard connectors for non-standard uses is a sure way to cause an ...


23

Twisting wires reduces the magnetic loop area of the wires, this has two implications: Reduced susceptibility to noise from magnetic fields, with twisted wires an a smaller magnetic loop area, external magnetic fields will induce less current in the loop made by the wires than straight cables. Reduced magnetic radiation from loads that are switching. A ...


22

To be compatible with the original standard, USB devices should not draw more than 100mA (which is plenty to power the logic interface), until they have negotiated with the host, to find out what it can supply. After successful negotiation, they can draw up to 500mA. This is to protect the operation of a 4 port hub, should it be plugged into a PC with all ...


17

Ferrite Beads and LDOs are typically solve two different kinds of noise problems, so very rarely will you be able to "replace" an LDO with only a Ferrite Bead. LDO's ability to filter noise is typically characterized as Power Supply Ripple Rejection (PSRR) and most LDOs are generally good attenuating Low Frequencies, but due to their bandwidth limitations ...


16

Historically: really old mainboards connect USB power pins to the 5V power rail, with no protection power on by keypress was added, which added a jumper or a BIOS setting that decided whether USB ports would be powered from the standby power or from the regular 5V rail. Since standby power was introduced in ATX, this does not exist on AT mainboards. USB ...


16

This is a fiber optic splicebox. It is a weatherproof enclosure where two (or more) ends of fiber optic cables are connected. Yes - electricity poles also carry optical fiber for control of the network and often internet access.


15

It's a junction box for fiber optic cables. Here you can buy a similar one.


15

Most certainly a surge (or in-rush) current problem. Electric motors, at start-up (when they are not spinning yet) and especially when driving a load (like turning the pump's impeller against water) draw enormous short-term (surge) current. This surge quickly dies out once the motor "gets going". From wikipedia When an electric motor, AC or DC, is first ...


14

Is there a reason this schematic uses an op amp (AD8031) for the reference voltage of the op amp (AD8544) filter when the voltage divider already brings down the voltage anyways? The usual reason to use an op-amp to buffer a divider like this is to ensure the reference voltage doesn't change if whatever it's connected to sinks or sources current. Can the ...


14

They’re adjustable power resistors. You loosen the screw and move the ring to or fro to get the resistance that you want and then tighten the screw. Probably a dummy load for various supply rails.


14

A quick look at the Radio Museum pictures and descriptions makes it look like it ought to be fairly easy to hook up. Here is the picture of the connections from the Radio Museum: You provide it with 4V through the jacks on the left side. You could use a battery pack with 3 normal AA or C cells in series. That's the easiest way, and will probably sound ...


13

The picture below should explain this: -


13

Is there a reason ... Yes. The two 10k reisistors give the voltage reference an impedance of 5k. This means that if the current drawn from the reference changes by 0.1 mA that the voltage of the reference would change by 0.1m x 5k = 0.5 V. This would be a very unstable reference. The op-amp buffer fixes this. The output impedance of the buffer is close to ...


13

If this is not possible, is there an existing type of cable that can achieve this (3 power leads and a ground), or will I have to solder my own? Cables will do whatever you want them to do, they carry current from one point to another. The biggest concern would be if someone accidentally plugged the USB cable into a regular USB device which would ...


13

To answer your comment to Puttafish, Why do they draw it on the power supply? Why not near the connector? The connectors are purchased with no polarity assignment. It's up to the PSU designer what the polarity is or if it is AC. Thus it makes sense for the PSU builder to label the polarity on the PSU along with all the other technical information. There'...


12

There are two AMS1117 fixed-voltage regulators on the board (the black SOT-223 packages). The jumper selects one of the two to go to the output.


12

20 watts delivered into a hand-cranked generator (enough to deliver 10 electrical watts after conversion losses) could be managed all day by a fit and motivated person. This would employ all of your arm muscles. However, you'd need reasonable length cranks, comfortable handles, a good secure mounting for the generator, it's not something you'd nonchalantly ...


12

NO = normally open contact NC = normally closed contact Normally open (NO) contacts connect the circuit when the relay is activated; the circuit is disconnected when the relay is inactive. Normally closed (NC) contacts disconnect the circuit when the relay is activated; the circuit is connected when the relay is inactive. All of the contact forms involve ...


12

C2, D5, D6 form a charge pump to produce the negative voltage required to allow the opamps to get down to the negative rail, it is a fairly popular trick when you want a supply that can vary right the way down to 0V (Which is otherwise a surprisingly hard thing to pull off). Charge pumps require the input to be AC (or at least pulsating DC).


12

No, it won't step up current. You can think of a regulator as a resistor that adjusts it's resistance to keep the voltage stable. However, you can buy DC to DC converters that 'boost' the current. But DC to DC converters are usually called by what they do to the voltage, not the current. A boost converter 'boosts' or steps up the voltage from a lower ...


12

You need two back-to-back P-channel MOSFETs for each power input. Here is an example from an Atmel eval board, though you'll want to scale up the MOSFETs considerably, and maybe reduce the resistor values to something like 10K: The VCC_USB input is dominant if both are present (in other words, if only one supply is present, that one will be used, if both ...


12

What are those parallel soldered-traces on the PCB traces? They are traces where some of the soldermask has been removed in order to allow solder to build up to improve the current capacity of the trace. The reason they left the narrow parallel lines of soldermask is so that the solder distributes itself more evenly across the width of the trace. ...


11

It seems you are making several beginner's mistakes in your understanding and application. You are using the LM2956 5.0 which is the 5 V version. This will output a regulated 5.0 V subject to meeting certain conditions including the required input voltage and current and having a load drawing between the rated minimum and maximum. The 3 A maximum output ...


10

What I wanted to ask, is such a circuit feasible? Practically not theoretically. I'll go with a "no". The time you'll spend in such an open-loop configuration to actually make things stabilize at the voltage you want will be quite substantial, and the slightest change in temperature will change how the transistor works, so: don't try this. Also, you'll ...


10

We've given your photo to the forensics lab and they suspect that it is a fibre-optic data cable using the electrical power distribution poles as the cable route. Photo 1. The enhanced image. The incoming cable. The cable clamp. The down-feed to the junction box where tap-off and through connections are made. The cable out to the next stage. The outgoing ...


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