53

Power dissipation will be the driver. Using six in parallel allows use of standard resistors which may be a stock item. Using standard parts allows use of automatic assembly equipment. Lower profile. Heat spread out over larger area resulting in lower peak temperatures. Ability to combine to make a non standard value. The 20 Ω in your question is not an E12 ...


24

Let's have a look at the pcb... It looks like they used several resistors for higher power dissipation. This is quite common, as several low power resistors may be cheaper than one high power resistor, especially if you already use the value somewhere else in the design, which means you already have them loaded on the pick and place machine so you don't ...


20

The cathode of the LED must be connected to the ground not Vcc


18

A brake is an electrogmagnetic component. It has a resistance but is mainly inductive. When the brake is turned off the current will tend to continue flowing and a spike or back electromotive force will appear which will overheat or destroy the transistor after it is blocked. Adding a freewheeling or flyback diode will allow current flow in this condition ...


12

In addition to the flyback diode problem, the fact that VCE (collector/emitter voltage) is 5.64V when the transistor is on means that it's not fully on. This greatly increases the amount of power dissipated in the transistor, which causes it to heat up more. Overheating can also damage a transistor. You might need to increase the base current by decreasing ...


9

If you look at the datasheet, you'll see a few important tips: This flux must be cleaned after you apply it, since its corrosive, and shouldn't be used on bits that you're not soldering. The latter is true for most (all?) fluxes. The reason that water solubility is important for this flux is so that you can clean the pcb with water, and dont have to use ...


8

Parallel resistors, greatly imbalanced in value, can be for trimming. If 1% at 1,000 ohms, then 1MegOhm in parallel will reduce the total by 0.1%. Parallel resistors will have a greater area, thus more vulnerable to electric field aggressor flux inflows. Parallel resistors may have more underlying Planes, to which HEAT CAN BE DUMPED through the insulating ...


8

An additional point that noone has yet mentioned: Redundancy If one high power resistor fails, the circuit is probably affected significantly. If one of your 120 ohm resistors fails (and nothing else does) then the 20 ohm effective resistance increases to 25 ohms, not an open circuit. Of course the chance of a single component failing and not causing general ...


8

For 10 watts into 8 ohm speaker, you can do this system design P = Vrms * Vrms / Rload 10 watts = V * V / 8 10 * 8 = V * V thus Vrms_out ~~ 9 volts RMS, or 2.828 * 9 peakPead You will need headroom. So have at least 40 volts VDD. Now for the gain: The topology of common_emitter amplifier, into a resistive load, has maximum voltage gain of VDD / 0.026; ...


4

SMD pros: smaller size, can be assembled by pick-and-place machine, no lead inductance or smaller inductance for packages containing leads. Through-Hole pros: bigger package - better power dissipation (e.g. resistors). Although it depends on PCB design. If SMD component is mounted on copper plane it may have better thermal drain as mentioned in comments ...


4

Could someone please explain to me why do we need a resistor at the non-inverting terminal of the summer amplifier The resistors R7 and R10 are there to remove a voltage offset at the opamp input terminals due to the 'common mode input bias current.' This is a dc current drawn (equally) by both terminals. The resistor is chosen to have the same value as the ...


4

This difference amp circuit should do the trick for you: I have simulated the thermistor R4 to vary over time from 8k to 12k ohms. The resistor R1, R3, and R5 were chosen to match the center of the thermistor range. This sets the common mode voltage to 2.5 volts, and amplifies the differential voltage caused by the thermistor varying with gain set by R2, I ...


4

For typical component sizes, E12 vs E96 or the selection of 5% or 1% components makes very little difference, since the cost of placement is much more significant than the cost of the resistor. However, while a 4000-part reel of resistors up to 1206 costs a few USD, prices go up very rapidly for larger components, although the performance does not. Using ...


4

Yes it does matter. Your two sections are rather oddly matched, as Tony says. I presume you know you'll have quite a bit of passband ripple, and it's the right decision for your application. If the high Q section is first, then high amplitude signals around the pole frequency will be amplified by the Q, and cause the amplifier to clip, i.e. become very non-...


4

As already mentioned, parallel resistors (of a given power rating) offer greater dissipation than a single one. Saves having to inventory 'special parts' too. Another advantage is that any heat generated is spread over a wider area. Helps avoid 'hot spots' on a circuit board. You can also use parallel or series resistors to produce unusual resistance values ...


4

Ideally yes. If you look closely, you may find it's some small but roughly constant voltage away from the input. This is known as the "input offset voltage" and can be up to 5 or 10mV in some opamps, 1mV in others, or microvolts in "chopper stabilised" opamps where DC accuracy really matters. (Check datasheets for the details) Some opamps ...


4

Gate Driver will not produce 0.2 nanosecond edges. The required charge must flow from 2nanoHanry to 10nanoHenry inductances in the gate driver's GND, VDD, Vin (03/3v?) and Vout (0/12v?). Given 2nH and 2nF are SLOW edges ( 60MHz ringing), you should alter your edge rate expectations.


4

Most electronic systems can be operated continuously if within their design ratings. The most common cause of concern is heat. Unlike say a high computational power desktop/laptop/server/mobile processor, a typical microcontroller doesn't consume more power than it can effectively radiate heat without needing additional cooling design. Provided that the chip ...


3

Use 2 Pcs HV5222PG-G, which is a 32-bit shift register ic. Or you can use any microcontroller to do so. You will need 42+3 = 45 Pins in total.


3

It’s probably simulating the op-amp balanced on a knife-edge, a valid solution mathematically but unstable and a situation that won't occur and can’t persist in real life. If you remove the initial condition calculation that usually gets rid of the issues .uic or add a voltage step to nudge the circuit.


3

Well, we have the following transfer function: $$\mathcal{H}\left(\text{s}\right):=\frac{\text{X}\left(\text{s}\right)}{\text{Y}\left(\text{s}\right)}=\frac{\left(1+10^{-\alpha}\cdot\text{s}\right)\left(1+10^{-\beta}\cdot\text{s}\right)}{\left(1+10^{-\gamma}\cdot\text{s}\right)\left(1+10^{-\epsilon}\cdot\text{s}\right)}\tag1$$ Where \$\alpha\in\mathbb{R}_{\...


3

Overview block diagram of single supply class AB amplifier. This is representative of a 4W into 8R amplifier which I built and so the shown 24V supply would be too low for your requirements.


2

An 'NC' contact of a contactor or relay, energised by the utility supply, is to be used to bypass the fan switch and automatically switch it on when the inverter is enabled. Since mains wiring is involved, it would be advisable for the modification to be carried out only by competent personnel.


2

Those are all the same* diode, just in different package. B330 in SMC B330A in SMA B330B in SMB B330C in SMC * The only difference I've noticed so far (in Diodes Inc's datasheets) is a lower peak forward surge current (I_FSM) of 80A for the B330A,B and B330C compared to the 100A rating of the B330 (nothing). I wonder why there is a difference in the ...


2

this causes some relays to stay energised for a second or two after power supply is cut off which is not ideal. ... what can cause a relay to stay energised after supply is out? Relay coils have pick up and release voltage ratings. Most relays can pick up at 75% of rated coil voltage and can remain until the coil voltage drops down to even 30%. The ...


2

You want to multiplex your LED's. This http://lednique.com/display-technology/multiplexed-display/ (Simple introduction) and this https://www.instructables.com/Practical-Guide-to-LEDs-4-Matrix-Multiplexing/ (more in-depth) are what you want to do. It's not complex or unknown. You just didn't know what to call it ;) You'll probably need some line ...


2

Headphone drivers (Class D or otherwise) for portables are limited in swing by the power supply. They do however use a few tricks to achieve greater loudness: (more expensive ones) full H-bridge drive (cheaper ones) common-mode bass drive To answer your voltage-conversion question, Class-D drivers use a kind of PWM-to-analog conversion that basically ...


2

First, I never used LTspice on Mac OS X so I can't 100% confirm, but I watched a video and the rotate command looks to be the same as it is in Windows. To rotate, either while you are first placing the component or while you are in the process of moving it with the move tool, you press CTRL-R to cycle through each of the 90° orientations. Second, it looks ...


2

For what it's worth, not an answer but more detail than a comment., If there is a signal where Q is highest, and any chance of saturation, it would be better last, as stage 1 attenuates at Qmax(f). But in linear use , they are interchangeable as there are no loading effects between stages.


2

Yes, absolutely. Only FLASH/EEPROM has write cycle resource usually. So care must be take if you write to these areas during operation with a some sort of wear leveling and managing. Other thing should last as long as they can if they are operating under normal conditions.


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