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H: How can I determine if this computer fan is dead?
Desktop computer fan started making noise then stopped.
We noticed it requires 12V and will run at 200mA.
I wasn't sure about that at first. Does that mean it has an internal resistance of :
12V / 200mA = 60 Ohms?
If so that means I could supply it with 12V and it... |
H: Testing spice model for common mode rejection ratio?
I've been trying to create a circuit to simulate common mode rejection ratio of an op amp to test the spice model's accuracy. While I've seen online that being able to use exact resistors only a simulator could use can be very helpful in determining CMRR, I can't... |
H: The relationship between power, heat and efficiency
I've been thinking about this conundrum.
Given we use joules to move a metal block over a surface, we do work.
So imagine a motor, that spins and pulls a string, moving said metal block over one meter toward itself.
We supply it with 1 volt, 1 amp and it needs 5 s... |
H: Edge-lit LED panel best materials?
I'm trying to replicate the effect of this LED panel I found at Home Depot with a different set of LEDs and use a differently sized panel. It's basically just a diffused light that mimics a window or skylight.
It's 2x2ft and produces 4250 lumens and has selectable color temps (d... |
H: How to Size Line Reactors and Understanding Reactor Specifications
I've got a 600 VAC, 75 HP VFD that I want to place line and load reactors in series with. Usually, I find charts like this that give me a horsepower table to follow as they are the easiest to use. However, today I googled sizing electrical reactors ... |
H: increasing output voltage of a schmitt trigger op amp
I have the Schmitt trigger circuit below that I read the output as 1.6V for the logic High. I wonder how can I increase the output voltage of the comparator below without changing the threshold of the Schmitt trigger?
AI: This might not be exactly right, but bec... |
H: Is this arduino motor driving circuit correct?
I got an Arduino Pro Micro and some parts to play with. I want to control a little 5v motor from an external power supply by using the Arduino to trigger a transistor. Like this:
Is that at all correct? Will it work? I want to experiment but I don't want to break my ... |
H: A phototransistor with LED and resistance in emitter
Earlier I used a simple phototransistor arrangement to detect an on/off signal via a laser pulse.
I connected the collector to Vcc(5V), and emitter was grounded through a resistance. The base was unconnected.
As soon as the laser would bias the transistor, I wou... |
H: What is the function of a capacitor in a motor circuit?
I read a manual of how to connect a speed controller to a motor. I see there is a capacitor as shown below. My question is what the function of the capacitor is? Thanks
AI: I think the speed controller is built to control a three-phase motor from a single phas... |
H: Why does the led turn dim gradually and then turn off when attached to a capacitor in series?
I connected an LED in series with the capacitor (any type of capacitor. I used one of 10 μF) and connected them with the 9V DC battery. I connected the positive pin of the capacitor directly to the positive side of the bat... |
H: Looking to get started with ARM microcontroller development on Linux
I am looking to get started in developing for ARM microcontrollers on Linux.
Keep in mind I really enjoy the low level. Right now I have some experience with PIC16F series and 8 bit AVR. This is on the assembler level. I much prefer the PIC ove... |
H: Ideas for a cheap, simple, common temperature sensing component?
I'm looking to make a device to regulate a heater to maintain 100-110 degrees Fahrenheit in a small, moderately insulated container. Specifically, I'm wondering what I might have in my parts drawer that would make a suitable temperature sensing device... |
H: Transistor Delay
I'm attempting to make an alarm for a freezer so that if the door gets left open, after 1 minute or so, an alarm will sound.
I've got something similar to the schematic below. When the switch is open the capacitor starts to discharge through the base of the transistor but I have the LED in parall... |
H: how many resistance do i need to safe the LED of PC814?
if i have a input of 5v (arduino HIGH) on the LED of a PC814, how is the value of the resistance that i must use before that, so i don't burn the led?
http://www.datasheetcatalog.org/datasheet/Sharp/mXtzyru.pdf
i couldn't find the voltage that it supports on t... |
H: How can a simple operation such as moving data from one register to another can be encoded into an instruction and executed in a single clock cycle.?
The simple point I'm trying to make for an essay Im writing. I'm completely at a loss as to how to answer this. Any help available? Sorry, I know this is not a well f... |
H: Add a Tunable delay to a TTL pulse?
How can you add a tunable delay to a TTL pulse?
My understanding is that this is the job of a PPL. I am not sure if a digital PLL delays a square wave or if it can also delay a single rising edge (which is desired). I am hoping to tune the delay from 0ms to 10ms with accuracy in... |
H: Solving for RC circuit transfer function
How do I calculate the transfer function of this circuit? \$H(s) = \dfrac{V_o}{V_i}\$
I apply the Kirchhoff's law at the node \$V_x\$ but I still have \$V_x\$ as unknown :
\$\dfrac{V_x - V_i}{R1}+\dfrac{V_x - V_o}{R2}+(V_x - 0)sC = 0\$
simulate this circuit – Schematic c... |
H: Why UPS for sensitive SMD development?
My friend suggests me UPS for SMD development. I already have a a surge protector over all devices. He recommended the UPS that transmit all energy through its battery and he recommend to find some silent UPS: some UPSs have a spinning coil or something like that.
Why UPS?
P... |
H: Total Harmonic Distortion
If a specific project specification says "...amplifier must be linear such that the harmonic distortions are maintained below -40dB...", does that mean that a THD of -30dB would meet the requirements or would something like -50dB be correct?
I ask this because I know with gain, \$ A_v \$, ... |
H: Do I have to keep an AGM battery on float charge 24x7?
I have a 50 Ah AGM battery that I use rarely (lighting during power failures, off grid camping, etc) - I use it a few times/year.
To prolong the life of the battery, do I need to keep it on a float charger all the time, or is it sufficient to use a timer to t... |
H: Error while trying to program my ATmega16A with extreme burner
Whenever I want to burn the hex file on my chip, the following error message always appears:
Power On Failed
Cannot communicate with target chip
The programmer I am using is AVR USB programmer, from ABLab Solutions. The software I am using for program... |
H: Ethernet communication between 2 controllers
I'm working on establishing communication via ethernet between 2 microcontrollers.
Its a stand alone system. Controller1 will interface with the user via a keypad. Controller2 will be interface with a couple of motors(via drivers).
When Controller1 receives keypad pres... |
H: Tuning an electric organ keyboard
I have an old (1960's) Whippany Dart combo organ. Each set of three keys has a tuning pot that raises and lowers the pitch of those three notes (turning clockwise lowers the pitch, and counterclockwise raises the pitch). I'm not sure what determines the pitch of the three distinct ... |
H: Do engineers still design for volume using discrete through-hole bipolar transistors?
As a hobbyist who likes plugging BJTs and discrete components into solderless breadboard for entertainment and education, I recognise that people like me are an insufficient market to make it worthwhile for manufacturers to contin... |
H: How step-down voltage regulators behave when their input drops below their output voltage?
How do the common low-dropout LP2950 and buck LM2596 regulators behave when their input voltage drops below their output voltage?
I'm driving a micro-controller board rated for 3.7-5.5 V with a 4.8V battery pack built from f... |
H: Can Transmission gates be used to implement 3 State Logic?
In my application, I need to use a common line shared between two peripherals, I have to indicate to the devices whenever the bus is free or not, hence I can't have push-pull output where the output is either 0 or 1 , as these states are generally used for ... |
H: How to know which element replaces which for a cache?
If I assume that the first element of the matrix that is fetched to the D-cache is a[0][0], for associativity 4, please tell me which element in which matrix that will write over a[0][0] in the D-cache. Since the formula for set associativity is
In a set-associ... |
H: Arduino IR practice vs. application circuit on 1838 datasheets
There is an explanation of wiring up IR remote controllers for beginners at arduino-info.wikispaces.com/IR-RemoteControl, which suggests wiring the output pin directly into an Arduino pin. I've tried this, works fine.
The application circuits given in ... |
H: BJT Amplifier Input/Output
In a CB Amplifier, the Base is common to both Input and Output. Why is Input applied at the Collector and Output at the Emitter?
Could it have been the opposite?
Similarly, for CC and CE amplifiers why are the chosen Input and Output terminals selected?
AI: Radio Frequency amplifiers quit... |
H: How do I calculate battery life allowing for duty cycle?
I have a battery rated at 2610mAh.
The device it's powering transmits to the network for 35ms during this time it uses 1.95mA of power. the rest of the time the device draws 0mA. I want to workout how long the battery would last in seconds.
Here's what I've d... |
H: SM8 package orientation
I've received chips PCA9306DCTR (from Texas Instruments) but they don't have any dot or notch to define it's orientation (i.e. where is the pin 1).
In the datasheet there is a picture of this chip (in SM8 package) and it has a notch. However chips I've received has only strip of different co... |
H: Inductor equivalent of capacitor's charge
Because inductors share similar equations in their charging/discharging cycles, I am wondering if inductors have something like charge.
Capacitors have capacitance and charge while an inductor has inductance and _?
Is there a V = Q/C function for inductors?
AI: Magnetic flu... |
H: Motor Driver, increase output voltage
I have a sabertooth motor controller and it is rated max 33v input. I need (at max) almost double that on the output. Can I hook up one of these to the output port, between the sabertooth and the motor and get up to 60 volts?
If so, What happens if the input voltage is less tha... |
H: Max switch current
I am in the process of designing my first PCB and I need to include some switches to open or close a circuit with a max current of 500mA at 5v. I have found a DIP switch that I want to include on the PCB but I am not sure if the switch can support the current of my circuit. The specification of t... |
H: Does a photo-coupled SSR need a series resistor for the internal LED?
I am trying to control an LCA710 SSR with an Arduino digital output. The data sheet says the control inputs are "CMOS and TTL compatible". It also has a schematic of the internals of the chip, showing an internal LED and photo-sensitive something... |
H: Invert a 555 Astable Output Signal
I can't believe how much trouble I've had figuring out how to do such a simple thing.
I have a variable frequency, variably duty cycle 555 configuration in astable mode. I'm using a set of pots to get a wide range of control. It works beautifully. The output is great, but I hav... |
H: Why do capacitors lose capacitance in series?
Unlike rechargeable batteries, capacitors have a lower capacitance in series. Why is this and if I charge each cap separately and then put them in series, will it still be a lower capacitance?
AI: The answer to this comes from considering what is capacitance: it is the ... |
H: TLP280-4 Optocoupler on 12/24V inputs
There is a STM32 device which has to detect several signals from other devices. The voltage of these signals can be 12V or 24V. Also these signals can be positive (i.e. 12/24V) or negative (connected to GND).
simulate this circuit – Schematic created using CircuitLab
First que... |
H: Making a K type thermocouple
It has been said that a K type thermocouple is just 2 wires of different types twisted together (basically). If this is so then can such a thermocouple be made with a copper and steel wire twisted together? What about copper and nichrome?
AI: A thermocouple is made from two different co... |
H: Difference between Ethernet and USART?
As i made literal study about protocols, I came across lot of protocols and there differences but i'm not sure of what is the major merits of Ethernet over USART. lots of websites explained about all the serial protocols such as I2C, UART, USART, SPI, CAN, RS-232 and there's m... |
H: Eagle: How do I make a component from a board?
I recently discovered the fantastic Arduino shield components in LadyAda's latest Eagle library. Now of course I'd like to make my own, using the mechanical layer from an existing Eagle board file. But the Google has been unhelpful on this topic. And my fumbling around... |
H: Does heat affect the magnetic field of an electromagnet?
I know that heat destroys perm magnets, but how about electromagnetics? Does heat affect the strength of an electromagnetic field?
AI: No, heat has no influence on the strength of a magnetic field produced by current flowing around a coil of wire. The streng... |
H: Circuit analysis of mono audio preamp (K1803 Velleman)
For a school project I have a question about the first part of the circuit below (amplifies at 20*log(220k/2.2k)=40dB). I know that U2A is the amplifying part of the circuit. The problem is U1A and what is the role of this? I think in many ways it resembles an ... |
H: Does this device which claims to reduce reactive energy from a house work?
I've opened a device that states that it can reduce the reactive energy from a house, by plugin it directly to the power outlet/wall socket. I think it is a con, so I've opened it and I saw this black box. Inside this box that I've opened ba... |
H: ReRAM CMOS compatibility (vs phase change memory)
When ReRAM is described as having good compatibility with CMOS processes, it means that ReRAM can be constructed with "standard" manufacturing processes, correct? Meaning that it can be grown with typical thin film deposition methods?
This, as opposed to phase chang... |
H: What can the source of 100Hz noise be?
I'm making data acquisition with an amplifier (amplifier is amplifying a transducer and is connected to a data acquisition hardware).
After I make data aq. I am plotting the output signal data in fast Fourier transform. It is a DC output from the amplifier. I observed a sinus... |
H: Problem graphing inductor current-time
I am trying to graph the equation VbackEMF = L di/dt
When SW1 is off and has been off since negative infinity, I realize that there is no current in the system.
Now I imagine SW1 being pressed. The switch can probably make a good connection in 0.1 seconds, and current in the ... |
H: Source for a 6-pin DIL "stackable" header (for Arduino ICSP header)?
Does anyone know of a source for a "stackable" 6-pin DIL header? I would like to use one on an Arduino shield I am designing, in order to carry the ICSP header from the Arduino up through the shield so it's usable with the shield still installed.
... |
H: Does an SD card in SPI mode respect chip select/slave select? Seems to be resetting in my application
I have an application where I have a microcontroller (NXP LPC1343) which is connected to an FPGA via 16-bit SPI. There is also an SD card using the same SPI port (MISO/MOSI) but with a different CS/SS pin (both are... |
H: Servo position with no pulse
I am using a PIC 16F884 to run 2 motors and 2 servos. The motors are using the onboard PWM module, and I am bit banging PWM for the servos on Timer 2.
With only one servo being controlled, it works perfectly, but when I add a second servo control, the timing becomes off because of th... |
H: Electret microphone with class a amplifier has no speaker output
I' m a relative beginner trying to build this audio amplifier, using this electret microphone, and output my sound to this 8 ohm speaker.
I'm getting no audible output.
I tested the microphone only, with no amplification, and there was indeed a small... |
H: Microcontrollers with extreme high temperature range
I am looking for components which works at high temperature. Especially I am looking for microcontrollers which works at 180 °C to 200 °C. I need to found microcontroller which works fine at extreme conditions. If the microcontroller have built in CAN interface ... |
H: Is there any possibility of dissecting a microchip to get data from its internal memory?
There are many devices that perform various cryptographic operations inside their microchips. One of their key feature is that the secret keys are stored inside of the hardware and never leave it. Since it is possible to revers... |
H: Signal bus in Kicad
I would like to know how does one design a signal bus in schematic in KiCad. I only worked in Eagle before and I cannot figure it out. E.g. - I have 5 digital signals going to another part of circuit and I want to connected them all to some other part without necessity to route them one by one. ... |
H: Long Range RF communication
After playing with Arduino and different kind of sensors for my garden, now I'm starting a new project for my free time.
I want to work with RF communications because I need a long range device for my application, about 2 Km distance.
The idea is to make only an identification of which u... |
H: Use old PC power supply for 24v solenoids?
I'd like to use the +12 and -12 leads from an old PC power supply to power 24v irrigation solenoid valves. The values are rated 0.22A inrush current and 0.1A holding current.
I only plan on 1 or 2 solenoids being energized at a time. I can arrange for them not to be initi... |
H: Can leaving rechargeable batteries in the unplugged charger for a few weeks cause batteries to lose their charge?
Is it okay to leave rechargeable batteries in charger even if it's not plugged in?
AI: Depending on the charger you won't know until you examine it, but generally I would say yes, it hurts your battery.... |
H: transistor loop to limit the current
I am trying to implement the DALI TX/RX circuit below.
The description says:
The other transistor (T2) is controlled by the current flowing through the
resistor (R1). If a DALI slave unit is connected, this current will be the
same as that flowing through the power transi... |
H: Triangulate with Ping
Is it hypothetically possible to triangulate the location within any accuracy of a server at an unknown location by using ping times?
9 computers with location known log on to a multiplayer server. The 10th player (unknown location) arrives. Can the pings to that machine acts as radii of circl... |
H: Why is it desirable in an amplifier to have high input impedance and low output impedance?
I've learned that it's desirable in an ideal amplifier to have high input impedance and low output impedance. Why exactly? What are the implications an amplifier has the opposite- low input impedance and high output impedance... |
H: GEDA - cannot edit attributes
I'm trying to design a circuit in GEDA/Gschem in Ubuntu. I could insert new components in the circuit but I cannot in the name change or add values. For instance when opening the window for attributes of a resistor, I cannot see 'value' on the list. I tried to add 'value' but the fiel... |
H: What is the difference between an alternator and a generator?
What is the difference between an alternator and a generator ?
AI: Realistically, not a lot. An electrical generator is any electro-mechanical device that converts mechanical energy (typically a spinning shaft) into electrical energy (a current). This is... |
H: Confusion over SMPS controllers/regulators
I am looking at datasheets for ICs like FAN4800 or NCP1337. Some of these are PFC boost converters and others are for other types of SMPS topologies.
My confusion is that I can't tell if these ICs are actually supposed to be regulating the output voltage. There is never ... |
H: Transfer Function Of Multiple Feedback Filter
Can someone please give me tips on how I could prove that the transfer function of the multiple feedback filter below is
\$
T(s) = \dfrac{ -\dfrac{1}{R_1 R_2 C_1 C_2 } } {s^2 + s\dfrac{1}{C_1} \left( \dfrac{1}{R_1} + \dfrac{1}{R_2} + \dfrac{1}{R_3} \right) + \dfrac{... |
H: Does a capacitor in an inverting op-amp make a difference?
Just a quick question, does a capacitor in an inverting op-amp make a difference to the transfer function? Or, are just the resistors taken into consideration?
Non-Inverting op-amp:
\$ \dfrac{R1 + R2}{R1} \cdot V_{in} \$
simulate this circuit – Schematic c... |
H: Would a capacitor labeled 470K be 47pf or 470pf
I have a cap labeled 470K. I would have thought for sure that it would be 47pf until I saw this link where it said if a capacitor has a 0 as the last digit, it is the whole thing in nano-farads. How can I figure out this without a capacitance meter. 470K 100V C is the... |
H: USB charging and powering circuit with MAX1555 and MAX1881
I'm new to (rechargeable) battery powered devices, but I found the following article about using the MAX1555 and MAX1881 for building a charging (via USB) and powering (µC-circuit, 3.3V, max. ~70mA) circuit. They describe the following diagram:
The MAX1555... |
H: Peak voltage rating means voltage drop?
This LDR is said to have Peak voltage rating of 400V in the description. Does this equal the voltage drop, meaning that I need to supply at least 400V or is it the maximum voltage value?
AI: 400 V seems a stretch for that. The LDR is claimed to be able to dissipate 400 mW, w... |
H: Sizing MOSFET gate resistor
I have an N-MOSFET gate connected to a 4043 logic. Id is about 100 mA. Both the 4043 and MOSFET have +5 V. I plan to use a 2N7000.
How large a gate resistor do I need between the 4043 and MOSFET? The logic output is sometimes switched rapidly. How fast? A motherboard HDD LED controls it... |
H: Op-amp input stage for Arduino Due ADC - guitar signal
I am trying to design an op-amp input stage to capture a guitar through an ADC, specifically the ADC on an Arduino Due (3.3V, 12 bit). I am aware there are numerous ways to configure and bias the op-amps. I have designed a simple circuit based on a inverting am... |
H: Doing FFT of electroencephalogram signal at 200Hz - what window size to use?
I got a brainwave EEG(ElectroEncephaloGram) sensor that is continuously sending data over to my program at about 200 data points per second. Can someone suggest what window/bin size I should be using if I want to do a Fast Fourier Transfor... |
H: ratiometric ADC, is it feasible to separate reference voltage and excitation voltage by an amplifier
I have a variety of bridge transducers (pressure, strain gage) with sensitivity of 1mV/V. Also, most 24-bit ADCs and analog frontend chips have a PGA with programmable gain between 1-128. This means that at the hi... |
H: What the name of this connector?
I've spent a load of time looking for the answer to this question, but I cannot find it. What is the official name of this connector?
AI: It's a female crimp terminal (sometimes called an open barrel or u-barrel crimp connector). More specifically, since it has the plastic housing, ... |
H: What is the meaning of "Register.Rd"?
Reading Hennessy's book "Computer Organization and Design" it is mentioned "Register.Rd" and "Register.Rs" but what does it mean? The .Rd, .Rt and .Rs parts I can't understand, on page 365:
AI: They are just generic ways of referring to cpu registers:
Rd is usually denotes a d... |
H: Wireless transmission of energy through a layer of non-conductive material
Is it possible to effectively transmit energy by electromagnetical induction?
I have a plate of nonconductive material (5-10 mm) and I would like to transfer electrical energy from circuit on one side to circuit on the another side without d... |
H: how to represent a bridge in eagle pcb schematics?
i'm trying to show that points 7,8,10,11 are connected to ground and point 9 is connected to R18 resistor. but the visuals is misleading. how to create that "jump"
(sorry i don't know the correct lingo for that operation, please edit if you know, thankyou)
AI: Ea... |
H: Can a linear regulator in shutdown mode have the output in parallel with a switching regulator
I am trying to design an efficient battery powered circuit using a 3.3V microcontroller (NXP LPC1343). One of the requirements is that the microcontroller periodically read a value from an ADC and based on this, power up ... |
H: Why Characteristic Impedance must be 50 ohms?
Where does this number come from?
For single ended it must be 50 ohm and for differential pairs 100 ohm. Why?
For PCB with controlled-impedance these are that common numbers. Outside of the PCB you can find others numbers for characteristic impedance. But what is the re... |
H: Why does grounding my switch cause the fuse to blow?
I'm working on restoring an old ATV, and I'm having a bit of trouble with the wiring. When I got the ATV it was missing the ignition switch, so I decided to replace it with this awesome looking switch instead.
Which I'm guessing, internally looks something like... |
H: Sensor decoupling and noise reduction
I have an Arduino UNO board, and I wanted to design a simple 'sensor shield' --since all simple sensors has 3 pins (namely, SIG-5V-GND) and it is convenient to connect bunch of them directly-- and thats where things got ugly.
Below you can see my very basic design,
As you can ... |
H: What is the reason that Bus resistance is normally small
I have seen typical bus resistance as few ohms. For example on MAChX02 1200 ZE board the bus that connects FTDI chip and the FPGA has only around 11 Ohm resistance.
Is there any specific reason for keeping bus resistance small?
Thanks in advance
AI: Unless... |
H: 1-pole and 2-pole DC circuit breaker
My question is rather simple, when and why do one use a 1-pole or 2-pole circuit breaker in DC (+24VDC and GND)?
AI: In many applications, it is reasonable to assume that under any plausible fault conditions breaking one particular power supply connection will safely interrupt a... |
H: How to connect 4MHZ crystal oscillator to get 16MHZ
I've 10 4 MHZ crystal oscillators. I need a 16MHZ clock signal. Can I connect multiple 4MHZ oscillators somehow (serial, parallel) to get 16MHZ?
AI: No, connecting them in series or parallel won't get you a higher frequency.
What you're looking for is a Phase Loc... |
H: Routing the circuit for a snubber diode on a PCB?
I understand that the "ideal" place for a snubber diode is across the terminals of the inductive device that generates the flyback. But in the interest of making my PCB design for an Arduino shield as "bulletproof" as possible, I would like to have a suitable diode ... |
H: Possible measures to make power supplies safe
I'm looking for a list of ways that mains-powered ELV power supplies with touchable terminals can be made safe in the case of transformer failure with primary and secondary coils becoming connected within the transformer.
One method I'm aware of is a feedback control ci... |
H: Charge LiPo battery with solar panel
I've a solar panel of 5.5 V and 100 mA. Could I use it to charge LiPo batteries using the MAX1555?
Of couse that the voltage will drop due to the the Schottky diode.
AI: I see no reason this wouldn't work. Of course, you can only charge a single cell at a time with the Max1555, ... |
H: Is De0-Nano an alternative to Arduino/RaspberryPi?
Arduino and Raspberry Pi are touted as ideal programming boards for beginners and hobbyists. Could De0-Nano fit in that role, too?
What does Arduino or RaspberryPi have that De0-Nano does not?
AI: Trying to compare the Arduino series and RPi to an FPGA of any capab... |
H: Interpreting the power rating of the refrigerator
My refrigerator is rated as 130W of power. I need to know how to interpret this. Does that mean if the compressor works for a whole hour then only it consumes 130W? Or is 130W the average power considering that the compressor will be sleeping for most of the time? T... |
H: Searching for standalone unix development board to connect DC motors
I though a bit about the board and came to the conclusion that it may be more intelligent to use a stand-alone component which provides serial ports and an unix os which I then can control over the network. I want to write the port driver myself s... |
H: MIDI sequencer timing accuracy using the Arduino
I build these music sequencers.
Only it's not exactly a sequencer, it's a physical interface for a sequencer. The sequencer is an application that runs on a laptop that the sequencer connects to, this thing lets the user make drum loops on the fly. It's pretty fun, ... |
H: Trigger Monostable 555 When Capacitor Raises above 0.5 Volts
So I want to trigger a monostable 555 to fire when a capacitor raises above 0.5 volts. My plan was to use a Zener diode to bias an NPN transistor that would trigger the 555. But I discovered the smallest zener voltage you can buy is 1.8 Volts.
Is there ... |
H: Best practice to switch +V or GND connection?
Consider LAMP1 and LAMP2 in the simple example circuit below:
Which is the "better" practice, using the switching component (here RLY1) to break the +V connection to a component that's always connected to GND, like LAMP2; or use it to break the GND connection to a comp... |
H: How can a Live-Neutral transformer fault cause 2000 Ampere to flow?
In this critique of an ELV PSU design, it is suggested that a "Live-Neutral" fault could result in a fault current of thousands of amps.
It says:
Fire – (d) the plastic had a UL94-HB rating ( which limited its use to a decorative enclosure); (e) t... |
H: Home made USB charger based around LM2596: Smoothing caps
I'm embarking on building a home made mains USB charger based around an LM2596 DC:DC converter. I had a couple of Newbie questions.
Can I connect 5 or 6 USB plugs to the output of the LM2596 (assuming it's set at 5v and I respect the aggregate current limi... |
H: Breadboards and ground loops
The book Practical Electronics by Scherz and Monk states (3rd ed., p 48):
A ground bus, or bus bar found in breadboards... serves as an adequate substitute for a single point ground.
Is this statement correct?
AI: No, the statement is not correct. A single point ground is used specifi... |
H: threshold problem on a Schmitt trigger op amp
I have the Schmitt trigger op amp on the below diagram. (channel A & B refers the oscilloscope probes on the following figures).
The resistor values are selected to set the trigger threshold as ~9.5 V and ~5.1 V and I use this page to verify the threshold values.
Howe... |
H: ATTiny45 Quadrature Decoder Pull-Up resistors
I am trying to use the ATTiny Quadrature Decoder from here.
The schematic that I have attached here has two external 10K Pull-up resistors.
I have looked into the ATTiny45 datasheet and it seems that the I/O pins already have pull-up resistors that you can enable. My qu... |
H: Current flows from the source towards the sink
I happened upon the following schematic:
simulate this circuit – Schematic created using CircuitLab
It's supposed to reduce the max.voltage between the GPIO input pin and the current source to 3.3V, since 5V * (10K/(10K+5K)) = 3.3V. The thing is - 3.3V is the voltage ... |
H: Power consumption of Arduino Nano (current draw low power)
Anyone got measurements of Arduino Nanos power consumption?
It guess it should be less than e.g. of the Uno or Mega as the USB part only get powered when connected via USB and so does the 3.3 regulator.
Also I should be able to easily disconnect the 5 V reg... |
H: How to light an LED when a voltage hits a certain point
Lets say I need an LED to indicate when a DC voltage reaches 5 volts or more. I don't want the LED to be dim when it is at 4.5 or anything. I just want it to be full bright at 5, 0 bright at anything below 5. Is there a way I can do this with discrete componen... |
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