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H: Calculating the resistor for a 12V pushbutton
Please note: Although this question tangentially involves a Raspberry Pi, this is really more just a pure electronics question at heart.
I'm trying to connect my Raspberry Pi 1 Model A to this pushbutton. I believe my pushbutton will be wired to the voltage source (PWR... |
H: Computing a mathematical expression using half and full adders
I am new to logical desing and I am not sure how to start the exercise.
The problem:
Assume that we have 2 assinged numbers of 2 bits (A = a1 a0 and B = b1
b0). Desing a combinational logical circuit that computes the S = 4A +
3B and uses half and ... |
H: What is this broken component?
This is an IP Camera circuit and after i put accidentally 12vDC instead of 5vDC this component has died with smoking. I want to replace this component with new one but i didnt figurate it out what is this component and have a closer look under magnifier find some clues as u can see pi... |
H: Getting CL of XTAL
I'm using a dsPIC30F4011 in my project and I want to put a 6MHz XTAL between OSC1 and OSC2 pins. The circuitry goes like this:
I want to know the values of C1 and C2 in the circuit, and I read somewhere that the formula is:
The XTAL I've bought came with this datasheet. There it says:
The thi... |
H: Does a capacitor store voltage?
I’m a bit confused about capacitors. I understand they store energy in a field by accumulating opposite charges on the different plates. So a 1 farad capacitor will store 1 coulomb of charge if subjected to 1 volt if I understand the math right.
1 coulomb is also 1 amp-second, so thi... |
H: If you plug in a bridge rectifier directly to a power outlet, and touching one of the outputs, isn't it like touching live wire?
If you touch the output of the Full bridge Rectifier, and the circuit is powered directly from the city power, does it shock you with every positive wave of the 120ac? How about a half br... |
H: Testing a 32-bit (or any "square" shaped) microcontroller
I know there are certain shaped microcontrollers that can fit onto a breadboard without using an actual PCB, like the Arduino. One can use normal jumper wires and utilize the breadboard to their own discretion with this type of microcontroller below.
This i... |
H: Battery life when using voltage booster
I have connected a 3.7v-4000mah battery to a load via a voltage booster MT3608 (3.7V to 12V) . load current is 100ma. how long does battery can work?
AI: For this you will need to consider your batter capacity in watt-hours. So for your 3.7V 4000mAh battery, plugging into the... |
H: Split Collector Lateral PNP Transistor SPICE Subcircuit
This question relates to the book Designing Analog Chips by Hans Camenzind.
I need to simulate a simple (one transistor) lateral PNP current mirror:
I am trying to understand how one can model a "split collector lateral PNP transistor" (Q1) using a SPICE sub... |
H: How to measure the inverse saturation current of a diode?
I'm trying to measure the inverse saturation current of a diode, for using it in the Schockley equation. I would like to know what is the best circuit for doing this. I already tried the following circuit, but I can't detect anything.
simulate this circuit ... |
H: How to implement a filtered user button
I want to add a user button to my schematic design, so I first take a look at what I consider it could be a good source: the ST Discovery board schematic.
Their use case is the same as mine: user button, microcontroller configuration unknown, Vdd at 3.3 V.
Their button looks ... |
H: How do power generators generate AC at a constant frequency?
As far as I know, alternating current is generated at power plants by converting rotational energy to electricity. The frequency of the AC depends on the rotational frequency of the rotor. In USA, the frequency must be 60 Hz, correct me if I'm wrong.
Howe... |
H: Charging an ideal capacitor through an ideal diode, forever
Some context for why I am asking the question:
I have application in which I am to charge a supercapacitor from a voltage source which is equal to the the cap's rated voltage. As such I considered using a diode in series with the voltage source in order to... |
H: Atmel UART - use interrupts or cyclic implementation?
I want to write a program that intercepts serial communication between two microprocessors. Therefore I chose the Atmega 162 featuring two UARTS. Now I want to decide if I write the code using interrupts (which makes things more compilacted)
or just in a cyclic... |
H: Star delta phase difference
All I read online is that in a Y-Δ connection of a 3-phase transformer the voltage(phase and line if I'm correct) on the secondary side leads the primary one by 30 degrees phase.
Does that happen regardless of which connection is the primary? I mean does it matter if the star is the pri... |
H: Perfboard/Stripboard insulation techniques and what material to use
I most often make circuits on perfboard.
Below is an example of a circuit, both bottom and top sides:
This circuit will be in a case but outdoors for many months.
In case of some rain leakage or humidity or rust ect, I want to protect this circui... |
H: SPI timing of 25LC1024
I'm using an EEPROM chip from microchip, it's doc gives the read/write timing as below:
I'm a little confused. From FIGURE 1-2, I think it will read data in at the rising edge of SCK. But from FIGURE 1-3, it only gives a "holding" time (t13) from the falling edge, and the minimum value of \$... |
H: How to limit current for voltage regulator/decrease power dissipation?
I need to power a 5V device that needs more or less 1.2A in order to work correctly. I'm using a 13.8V power source with two diodes in series (1N4007) to limit the voltage to roughly 12V. I tried using the voltage regulator AZ1084T, since it has... |
H: How do I do to solder the adapter in the port and still use the same usb port without ruining the notebook?
I have a laptop that the wireless network card does not work, but I do not want to use my usb input for putting an external adapter, my idea is to open the laptop and solder the adapter inside the notebook in... |
H: Are S/R flip flops still relevent in digital design?
As I understand it, and please correct me if I'm wrong, one of the main drawbacks of using an S/R flip flop is that it can find itself in an illegal state with both S & R both with a logic value of 1.
The J/K flip flop remedies this by having a clock circuitry p... |
H: 5V to 3.3V and 5V to 1.8 or 5V to 3.3V and 3.3V to 1.8V buck converters
I have a 5V power supply that is converted to 3.3V using a buck converter. Now I want a 1.8V supply. What is the industry standard way to feed a 1.8V buck converter? Do we feed it from the 5V supply or from the 3.3V supply?
From an efficiency p... |
H: Relay Contact Rating (DC Power) at different DC voltages
To note, I have Google searched this question for the last 2 hours with many contradicting answer and searched Stackexchange with no clear answer.
I need to determine if a relay with a Contact Rating of 10A 250VAC/30VDC can handle 25A at 12VDC and if it woul... |
H: Why is the current control knob in DC voltage source kept at maximum initially?
In a DC Voltage Source(0-15-30V), why do we need to keep the current control knob at maximum at the beginning?
Note : I am using this DC Voltage Source for basic experiments of electronics like getting characteristics of P-N junction di... |
H: Replace laptop's usb surge protection chip
I am fixing an old laptop from 2008 (eMachine e525) on which everything works fine expect the 2 usb ports that are not powered.
I found this video¹ from Ingmar M. on youtube (very helpful video, thanks!) and I tried, like him, to desolder the 6 pin chip that is said by thi... |
H: Grounding and unisolated power supply
Okay I need to understand this concept because I'm playing with mains and I do not want to fry myself...
A little background : I'm quite good with low voltage stuff as well as logic level design but I've a big lack on switch mode power supplies . Due to a project requirement to... |
H: When to use milliamps or just amps?
So I'm doing this assignment that requires me to find missing elements in a power formula (Power = I (Current) * E (Voltage). The formula is easy enough but I'm not sure on the units to use for I.
From what I understand there are 1000mA (also equal to 1 amp) in 1 Watt. So if that... |
H: MOSFET Mode determination
I am looking into using a MOSFET in the ohmic region at a given VGS. However I am having trouble interpreting the typical I-V curve of a MOSFET.
Surely the y-axis parameter, i.e. the drain current, is generally the parameter that is changed by the x-axis parameter. But in this case, surely... |
H: opamp heating in voltage controlled current source
Well, I have a serious problem with heat in my circuit. I was trying to build a voltage controlled current source. Everything went fine in the building process. But when I turn ON the power supply the TIP122 gets very warm and so do the IRF820. I know this guys ten... |
H: How to find the equivalent resistance for this network of of resisitor using the basic parallel/series combination?
You can only use the simple techniques you use to combine parallel and series resistors. Nothing else.
The difficult thing about this network of resistor is that: every node besides a and b has 3 or m... |
H: Power connection vias on 4 layer PCB
I am new to PCB design. I am creating a 4 layer PCB with the following layer stack:
Signal (1) - GND (2) - Vcc (3) - Signal (4)
Now, I'll need Vcc and GND on both the signal planes. This means I'll need blind vias from 1-2, 1-3, 2-4, 3-4 but the PCB manufacturer I chose said t... |
H: Electric Fan Power Consumption
I am not sure but I believe the usual electric-fan switches its resistance value to change the power output.
Q1. With that case, does the resistor consumes the power?
Q2. Do switch #1, #2 and #3 consume same amount of power?
If the answer for both Q1 and Q2 are true, then turning the ... |
H: Power Supply Card of Float Charger 150A
Please, can someone explain me how the transistors here reduce the voltage from +40 VDC to +15V in the positive side (upper part of circuit)
These are the voltages observed across different components of the power supply card.
O/P Positive side : + 15.40
O/P Negative side : ... |
H: How does a CM choke reject common-mode noise while allowing the signal of interest?
As far as I know a CM choke is nothing but a transformer(?).
How does it block common-mode noise and pass the signal of interest? Should we think of it as an LR filter? And how to size it if we know the signal of interest? A pictori... |
H: IO Cathode PINOUT
I have to connect a peripheral 1-Wire 13.56Mhz RFID Reader
https://doc.ruptela.lt/pages/viewpage.action?pageId=884781) to a device.
The only info I have from the device ((FM-eco4/4+ ruptela: http://www.ruptela.com/product/fm-eco4/) ) is this one:
PIN WIRE COLOR DESC
10-32 V Red ... |
H: Why a CrowBar is called a Crowbar?
I know the naming can be funny , but still it amuses me why a over voltage protection circuit is called a crow bar . https://en.wikipedia.org/wiki/Crowbar_(circuit)
AI: Which part of the very first paragraph of the Wikipedia article is not clear?
... much as if on... |
H: Several questions about the ADC LTC2323 function, I'm new in electronics
http://www.manuallib.com/pdf/2014/0707/linear-ltc2323-16-input-adc-datasheet.pdf
this adc is part of a little project I have to interface and fpga with this adc.
I want to understand how does the source signal input in the ADC and how does it ... |
H: Problem with mixed CMOS op-amp supply voltages on a square to saw wave converter
I am designing a square wave to saw wave converter by first integrating the square wave into a triangle wave, then toggling between the triangle wave and it's inverse, using 2 CMOS 4066 switches triggered by the original square wave.
... |
H: How to allow a motor to free spin?
In my circuit my motor terminals are connected to the output of a VNH5019A motor driver https://www.pololu.com/product/1451. When the circuit is no longer powered I want to allow the user to freely rotate the motor (a dc motor) output shaft (which in my application has a load atta... |
H: When would I not want to replace a PN diode with a Schottky diode
When repairing or maintaining equipment, or even during design revisions, why would I, for electrical reasons (not interested in the potential financial aspects) not want to replace a PN junction with a Schottky diode? Three reasons I can come up wit... |
H: PIC32MX Timer 1 Interrupt on Uno32
I have Chpkit Uno32 with PIC32MX320F128H, I am trying to enable interrupt and I have written the following code:
// PIC32MX320F128H Configuration Bit Settings
// 'C' source line config statements
// DEVCFG3
// USERID = No Setting
// DEVCFG2
#pragma config FPLLIDIV = DIV_... |
H: VL6180x sensor breakout stays on despite removed VIN
I'm experimenting with a couple of VL6180x distance sensors on breakouts (http://www.ebay.com/itm/172823051918, the blue ones).
Because the sensor resets its i2c adress when the power is removed, and because I want to use more than one, I need to be able to set t... |
H: Using Bench Power supply to charge NiCd pack
I have an 18vdc battery powered drill hat works fine but the charger has died and a replacement is $54. Almost double what I paid for the drill plus battery plus charger two years back. Battery was still holding a good charge.
The label says, 18vdc 1.2Ah Battery pack
I d... |
H: Input coupling to Class AB amp with diode bias. One capacitor or two?
When AC coupling the input signal to a Class AB (Push-Pull / Complementary Pair) which is diode biased I see two different approaches:
Signal connected between biasing diodes with single decoupling capacitor:
Signal connected directly to each t... |
H: Driving a Strange 12-Pin, 7-Segment, 4-Digit LCD display
I am putting together a project that requires a 4-digit numeric display and wound up ordering this. Unfortunately, something I completely failed to notice when ordering the LCD was that its pin assignments seem to be... incredibly bizarre. At least to my rela... |
H: What does the "2" indicate in 2:4 format for Excellon drill files?
For Excellon drill files, I know that the number after the colon indicates the precision, i.e.
2:3 has 1 mil resolution
2:4 has 0.1 mil resolution
2:5 has 0.01 mil resolution
However, I don't know what the number before the colon indicates. What... |
H: Adjustable LDO output became unregulated
I designed a simple LDO circuit using LM1084 (circuit A as in the picture) to power a small MCU board (circuit B) and the two circuits are connected with a 40cm wire because of installation constraint.
When the circuit B is not connected, circuit A can output 7V as expecte... |
H: Need detailed working or explanation of SCAN register in DSPIC
I am not able to figure out the working of SCAN register in DSPIC30F2010.I need to read 4 analog inputs in ADC and for that need to set the sampling and conversion
AI: From dsPIC30F2010 datasheet,
The inputs are selected by the ADCSSL register. If a pa... |
H: Reliability and MTBF
For an electronic device the the MTBF requirement is 4500 hours per year for 10 years, what does this MTBF mean and how to convert it into hours?
AI: MTBF means mean time between failures, so on average every 4500 hours there is a failure. This is for the first 10 years. Since there are about 3... |
H: A weird heat sink
I recently come across several items employing a special type of heat sink structure .
Usually I see plate fin heat sink or pointy fin heat sink, they all have fins that are uniformly distributed.
Like this(Wakefield-Vette 655-53AB)
or this (Wakefield-Vette LTN20069)
.
But the ones listed belo... |
H: Does a rated 5V, 2.1/1A charger provide a constant current?
I use power banks often to charge my iPhone. The default charger is a 5V/1A charger (which I assume provides constant current).
However, the power bank has 2 output ports - able to provide 5V=1A and 5V=2.1A - Does this mean it provides constant current or ... |
H: Measuring Low Magnetic fields
Im working on a project where I want to measure low magnetic fields in a wire. The range I want to measure is 0.1 - 10 mG or 0.01 - 1 µT in low frequencies (DC - 500Hz) (This range (0.1 - 10 mG) can be larger but I want a accurate measurement in this range).
I looked into hall sensors... |
H: Is it always good to have positive slack in STA?
You may find this question easy. But it has been confusing me for a while now I really wanted to make it clear out of my mind. The problem is: Is it always good to have a positive slack along a timing path? Since slack is calculated as Required_Time - Actual_Arrival_... |
H: Pole calculation -180 not +180 phase
Gain in feedback system is defined by:
\${V_{out} } /{V_{in}} = A / (1+Af) \$
We have a pole when \$|Af|=1\$ and \$\angle Af =-180\$
Any complex number can be expressed as \$z=r(cos \theta +j\sin \theta)\$
But when \$\theta=180 or -180 , cos \theta=-1\$ in both cases and sine is... |
H: Lightning Rod Hack By Using Satellite Dish
Our condos' rooftops don't have lightning rods per se, but they do have satellite dishes and AC units mounted there as well. Would these, if properly grounded (and these should be) act as lightning rod "hacks?" This question just hit me like, well, a bolt of lightning !... |
H: Arduino and motor driver l298n separate power supply circuit
I have an inquiry regarding the l298n motor driver.
I encountered a problem while using it. It's like this: every time i attach the wires of my dc motors into the board's "motor A" and "motor B" connectors, my dc motors wont move. I re-checked my code to ... |
H: What does a slash over a line in a circuit diagram mean?
In the following diagram (from the book by William Stallings, Computer Organization and Architecture), what does the slash / over the lines mean?
For example, there is a / through the line labeled s + w on the top. Why is it there, and what does it mean?
AI:... |
H: 50 hertz sine wave in oscilloscope when I touch it
I bought a new PicoScope USB oscilloscope and noticed that when I touch the tip of the probe with my hand I see a 50 Hz signal of 2 volts on the screen. What is causing this? (Or rather, how is the mains 50 Hz sine wave getting through me to the scope?)
AI: There i... |
H: How to Plot X/Y in Java Circuit Simulator
Does anyone know how to select the Y variable when doing an X/Y Plot in Java Circuit Simulator? I tried many things and none have worked.
AI: To create an X/Y plot in Falstad's Java Circuit Simulator, do the following:
Right click on the component that you would like to me... |
H: Help with capacitor circuit calculations
Hopefully somebody will be able to help me better understand how to calculate capacitor change and everything else. I just started studying them. The problem and my attempt to solve it is below.
How would I go about to get E (energy) and Q for each capacitor? thanks!!!
EDIT... |
H: Recapturing side and back lobe radiation from a directional antenna
When you look at the radiation pattern for a directional antenna, you see a major lobe where the greatest concentration of radiation is found and side and back lobes that have much less concentrated radiation.
I was wondering what methods, if any, ... |
H: What are the things to be taken care of while buying a crystal oscillator?
I need an external crystal oscillator for PWM output of 10kHz using dsPIC30F2010
AI: Typically you can either buy a crystal and place your own components around it, as usually described in various MCU data sheets, or you can buy a self conta... |
H: Can a GPS receive its signal from within the engine compartment of a vehicle
I want to place the GPS and GPS antenna inside the engine compartment of a vehicle. Will the device acquire an accurate fix?
AI: Probably not, GPS works with extremely weak EM signals from the GPS satellites. These EM signals cannot pass t... |
H: What does this op-amp circuit do? (part of an ECG)
I would like create an ECG circuit based on this schematic (from the AD620AN datasheet):
I don't know this part of the circuit and how it works. I know this is called a right leg driven circuit which is reducing the effect of the noise. But I don't know exactly ho... |
H: Splitting induvidual WS2812B LEDs
My motherboard has a WS2812B header for use in addressable RGB LED strips. However I am not using them for those strips, as instead I would like to use the signal to separately control several other RGB LED devices (fans, reservoir, GPU, monoblock, ...). The WS2812B connector itsel... |
H: Damaged Solder Joint?
So I bought a SEGA CD off ebay and everything was fine until I decided that the duct tape that was holding the battery is was a poor substitute for a battery holder.
So I took my Model 1 apart begun to unsolder the joints that held the battery down. However, one of the parts snapped off and my... |
H: Converting 32 bit 2's complement to decimal number
I have data coming from a V9261F energy measuring chip (link to datasheet), that sends it data through a UART to my Arduino microcontroller. When I read register 0x0119, I read the active power measured by the chip. But the problem is that this feedback is in 32 bi... |
H: current through the smoothing capacitor in bridge rectifier
Can any one tell the reason for the current through the smoothing capacitor to be pulsating in the full bridge rectifier.
I have attached the screenshots of the circuit and the wave form obtained in Multisim.
AI: The diode will only conduct current to the... |
H: Ideal Transformer equations when the secondary winding is short-circuit?
This is my problem
Now I know that ideally $$V_1/V_2 = 1:α$$ and $$(J_1-J_3) = α (J_2-J_3)$$
where J1 is the current of the left mesh, J2 is the current of the right mesh and J3 is the current of the mesh in the middle(the one that passes t... |
H: Decoupling capcitance
Just a quick question about decoupling capacitors here, hopefully will be something nice and easy!
Let's say you are designing a circuit with 4 IC's that all need a decoupling capacitor. Some datasheets specify the minimum value of decoupling capacitor that should be on the PCB. Let's assume a... |
H: High power LED on aluminium core PCB
I'm working with a high power LED(40W heat dissipation) on a single layer aluminium core PCB.To calculate the required heatsink it did the following:
\$P = 40W\$
\$Rjc = 0.6K/W\$ (datasheet)
\$Rcpcb = 0.77K/W\$ case to PCB. This is the thermal resistance of the isolation layer(M... |
H: Using Matlab to send digital signal from National Instruments device
I currently have a circuit set up with an NI USB-6501 connected to a mux and was wondering how to use MATLAB to send a digital signal from the NI device to the mux.
AI: The link provided by Warren is for analogue. Click here for digital.
From what... |
H: class AB amplifier distortion
Building a simple class AB audio amplifier to drive a 16 ohm, 5 watt speaker from my phone streaming music. I have found many circuits on line, and am just building a simple version. The circuit is as below
simulate this circuit – Schematic created using CircuitLab
I am getting alot... |
H: What is the purpose of the gate runner on a semiconductor die?
With reference to the image of a FET die below, the gate pad is used to make connections from the die out to the device package. But what is the purpose of the gate runner? Why does the gate connection need to run around the device like that? Is any el... |
H: Calculating a good charge current for 3s156p 18650
I have built a 3s 156 p Samsung 22p pack to use as a house battery in my van. I'm trying to find a charger for it. Currently I am using my balance charger tenergy tb6b. Here is a screenshot with the data sheet on it. How would I use this information to calculate ch... |
H: When do I connect to negative terminal or ground?
Easy question (or at least I think). I've installed a siren in my vehicle which calls to pull power direct from the 12 volt battery. I currently have the circuit completed by connecting to the negative terminal on the battery. I've been told that sometimes it is ... |
H: Integrating on-off-on-off switch with Raspberry Pi GPIO pins
Please note: Although this question involves a Raspberry Pi, I believe it an electronics/wiring question at its heart.
I'm new to electricity & electronics and I'm trying to get this simple on-off-on-off switch to work as a pushbutton to my Raspberry Pi ... |
H: Range of 1 volt radio wave
I have a simple question how much radio wave produced by 1 VOLT can reach in KM , i mean it will be detectable in which range , without any mountains walls ..etc just on flat surface with air?
AI: Given 0.632vpp is 0dBm (i.e. exactly 1 milliWatt) across 50 ohms, we'll use that power level... |
H: Is a hardware register the same as a processor register?
I have tried searching for the difference between these two terms but everything I find gives ambiguous results. What is the difference between a harware register and a processor register, if there is any?
AI: A processor register is a storage element inside ... |
H: Analog circuit to maintain a minimum current?
I am looking to get a USB battery pack for use with both my phone and my bluetooth headset, but my bluetooth headset has a drain of only around 50mA when charging, and it seems that most battery packs have a minimum current draw of 50mA, below which they will shut off (... |
H: custom built computers
When buying an off-the-shelf computer I assume it gets tested to make sure for example that the power supply meets the regulation, the battery and usage does not exceed the limits etc.
How does it work when building or substantially customising a laptop/desktop, is it the case that the parts ... |
H: Thevenin network without resistance?
I'm trying to find the Thevenin equivalent network for the circuit below.
But whenever I solve the equations, I always end up with V(t)=2V_a - 3i_s and
can't get any expression showing V(t)~i(t) relationship. There's no way Thevenin resistance does not exist, but I can't get t... |
H: BGA prototyping practices
I'm working with a few BGA chips of a very fine pitch 0.5mm even smaller sometimes. What is the practices for being able to essentially breakout all the connections from these chips? I've just been dead bugging them for now but that's a very time consuming process and it has caused damage ... |
H: op-amp circuit explanation
Hi everyone I'm studying Op-Amp but I can't understand this point in the AC circuit :
In the first picture it says Vo = Ic * Rc,
and in the second picture I have the value of Ic,
when I try to apply this in the given formula before the answer is wrong. Why?
This second formula is used i... |
H: What is the practical advantage of using mirrored signal outputs eventhough what matters is balancing the wires?
Some devices output differential outputs since both wires carry varying signals which are mirrored. Most devices on the other hand output one signal carrying and one GND wire. There is also differential-... |
H: Why is there an extra resistor on the opamp in the LM399 datasheet?
While looking at the LM399 datasheet, I noticed on the portable calibrator application there is a 5k resistor between the output of the opamp and the noninverting input. It looks like it forms a voltage divider with the 200k resistor, but I cannot ... |
H: How to determine a current is AC or DC by use of analog multimeter?
How can one determine a current is AC or DC by use of an analog multimeter? Or its workaround with rudimentary tools or equipment ?
AI: Analog multimeters are normally based around a DC microammeter. Each DC volt range adds a suitable series resis... |
H: Why AND gate is positive Logic?
Why AND gate is considered as Positive Logic and OR gate as Negative Logic
AI: What is de Morgan's Rule for AND Gate?
Answer:
AND = the negative logic rule using the OR gate.
Whereas the AND could replace an OR gate using the negative logic, where 1=true, 0=false for positive logic... |
H: Resistors before every led?
I'm working on lighting up an entire LEGO city from my nephew. But the problem is I need a lot of leds with different amperes and voltages ( I'm gonna put them in parallel). So my 2 questions are :
Do I need to put a resistor before every led? or can I just put a resistor in front of a... |
H: Are switched jacks ever used for in-system-programming connections? (If not, why not?)
It seems like a switched jack would be a straightforward way to make pins do "double duty" in a uC-based application. That is, the "normally closed" connections of the jack could connect the programming-related pins to the applic... |
H: Effects of using voltmeter w/ 20 kΩ impedance across 35 kΩ resistor?
Our professor assigned the following question:
Describe both quantitatively and qualitatively the effects of using a
voltmeter to measure the voltage across a 35 kΩ resistor if the
voltmeter has an input impedance of 20 kΩ. Assume the 35 kΩ r... |
H: Help identify oscilloscope
If someone could identify the following it would be much appreciated. I am
assuming it is an oscilloscope of some sort.
The device needs a lot of TLC; grounding the inputs leaves a small Lissajous like figure on the display, so all is not well.
If I could get a manual that would help, I d... |
H: When an open-drain output asserts low, where does the line capacitance discharge?
I was looking at the auto-retry functionality of the TI part TPS2553 (datasheet http://www.ti.com/lit/ds/symlink/tps2553.pdf) and came across something I didn't understand and thought it a good opportunity to ask a general question.
I... |
H: How to derive an equation for the delay time to LED shutoff?
The question asks to create an equation for the time delay for the LED to turn off in terms of capacitance(CT), reverse current (IL) of the 1N4148 and the threshold voltage (Vt) of the MOSFET for the circuit below.
The hint given was that we can treat the... |
H: Is this a flip-flop?
What does this circuit do? It looks a little bit like a flip-flop to me, but it doesn't exactly match the circuit for an SR flip-flop on Wikipedia.
Is this just a different way to implement an SR flip-flop, or is it something else entirely?
Thanks!
Edit: To clarify, DTR and RTS in this circui... |
H: Ferrite transformer at mains frequency
Is it reasonable to use a ferrite transformer from a big SMPS (LCD TV power supply) as a mains transformer, assuming I split the transformer in half and rewound the coils to provide the proper impedance? Ferrite transformers are generally operated at high frequency, but I don'... |
H: STM32 Flash mass erase from IAP
It might be a silly question but I can't figure out in what cases a flash mass erase from in-application programming (IAP) is relevant, as it would erase the user code as well?
For STM32 devices, ST provides example code in reference manuals like this one:
A.2.4 Mass erase sequence c... |
H: How can a common mode choke filter differential noise?
Consider the following schematic, where there is a 10V offset voltage source with 1V ripple, two selfs mounted in common mode choke and a 100 Ohm resistor. Everything here is "ideal" (no parasitic resistance or capacitance etc.).
Since the current that enters ... |
H: Output frequency of asynchronous and synchronous counter
I read that output frequency of asynchronous counter will be \$\frac{f_{in}}{2^n}\$ where \$n\$ is number of flip flops and \$f_{in}\$ is input frequency.
In synchronous counter will the output frequency always be \$\frac{f_{in}}{2}\$ ? As clocks are activate... |
H: MIC6270 comparator - input voltage higher than supply rail
I've read in various places (such as here) that you can't safely feed an input voltage to an op-amp / comparator that's above its supply voltage, even when within maximum ratings.
However, the datasheet for the MIC6270 states a 2-36V supply, and also states... |
H: How to identifiy this "2222 063 90025" vintage capacitor?
I am restoring an old stereo valve amp and would like to test (and replace if needed) some components. I don't know the history of the amp, but it's made in New Zealand and looks to be from the 1960's or 70's, but I could be wrong.
There are a couple of cap... |
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