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H: The importance of knowing that charges only occur in nature as integral multiples
So I read the following about electric charge from Fundamentals of Electric Circuits (fifth edition) by Charles K. Alexander and Matthew N.O. Sadiku :
"According to experimental observations, the only charges that occur in nature are... |
H: PIC microcontroller voltage drop
It is my first project with a PIC microcontroller, so I am sorry if my question seems too basic.
I have programmed the PIC as a frequency counter with two inputs: one input for a PLL, and another input for a clock (I am not using an external oscillator... This clock is used as a win... |
H: Parallel resistor algorithm
I have build a circuit that functions as a variable load. It consists of 4 resistors in parallel - let's call them R1,R2,R3,R4 - each with an activation switch (implemeted with a transistor). R1 has the lowest value, the other resistors have value: Rn = R1*2n-1.
I'm currently trying to f... |
H: Oscilloscope probe compabitibility
I bought a very old Philips oscilloscope some time ago (see my post. This is a Philips PM 3253). Although this Philips really has a lot of features, I cannot really use it well, since I cannot do good readings below 1 MHz because of the bad screen (focus problems, lines stay very ... |
H: how to connect i2c peripherals to digispark Attiny85
I am new to micro controllers and I have problem with understanding and connecting I2C devices to Attiny85 digiSpark micro controller.
According to this picture SDA and SCL are on the same pin and I am confused how can I connect any i2c device to this controller.... |
H: How does this CMOS OTA with common-mode feedback work?
In class I learned about the circuit shown below. It is basically a simple CMOS OTA with a common-mode feedback realized by a resistive divider. But I am not quite sure how it works.
Lets say that I have a VDD of 1.8V and I want my common-mode level ideally at ... |
H: Why is this opto isolator input turning off so slowly?
I feed a nice square wave into Q1/2, and on U40/1 I see a full turn off take almost a millisecond! What is happening, and can I fix it (ideally by not adding components)?
AI: There is some capacitance associated with the input. When the transistor turns off, th... |
H: How to do Non contact USB wiretapping?
I am relatively new to electronics but came up with this project, not for nefarious purposes but simply as a cool project. Simply put I want to try and read the data traveling through a USB cable with a non contact device (like a digital clamp meter but for dc). I have looked ... |
H: what is the main differences between the capacitors?
I have read many documents on these terminologies. I find almost same working for these capacitors.
Please make me clear what is the main difference between bypass capacitor, decoupling capacitor & smoothing capacitor?
Thanks
AI: They are all capacitors with diff... |
H: Can AC floating ground be used as a common ground to a DC circuit?
I'm designing a system that uses a power supply to convert 120V AC current from the wall socket to 12V DC current. I'm looking at a Jameco SP-240-12.
Originally I thought pins 4 and 5 output negative DC current, meaning I would have to ground my c... |
H: The reason for multimeters to have a high input impedance
My question applies not only to multimeters, but all devices which require a low or a high impedance at the input or output.
Based on my understanding, a device would require a high input impedance, so that the input signal does not get affected by it. In ot... |
H: 240VAC to 240VDC
When a 240 Vrms mains voltage is rectified with a bridge rectifier and reservoir capacitor, the output voltage becomes 340 VDC, on average. Then, I would put a buck converter that oscillates at 20 kHz (say) and step it down back to 240V. But how would you regulate that 340V down at 240V AND elimina... |
H: 120v DC to 5v DC conversion
For our e-Kart project we need to power a raspberry pi 3 (5V 2A) of a battery of 120V.
We are having trouble finding a good solution as these high voltages seem to high for a conventional (self made) SMPS and its not AC voltage that needs conversion.
Someone suggested using a normal USB... |
H: How do I generate ~50 microamps of DC across dynamic resistance?
How do I generate ~50 microamps of steady direct current across a load (tissue sample) with dynamic resistance that varies between 2kohm and 20kohm with good visibility into circuit operating conditions and safeguards against elevated current and volt... |
H: Converting pulse into volt?
I am working on the lab which is allowed to ask other people for hints.
Below picture is part that I don't understand.
In the image, program called "Audacity" is used to capture that waveform.
My question is, is there a way to convert each Y-axis values of each pulse in signal in audaci... |
H: Charge battery with AC
EDIT:
Question 1: what type of current will be created when passing magnets past a coil? AC or DC?
Question 2: What is the best way of storing the electricity generated with a contactless dynamo?
I'm working on a contactless dynamo project for my bicycle, (similar to this project: http://www.... |
H: LVDS Displays - Swapped EVEN and ODD Channels?
A friend of mine gave me 2 LCD display driver boards (VGA/HDMI to LVDS). One has RTD2553V chip (from Realtek) and the other has RTD2660H (I cannot share the datasheets because they are not public). The main difference between them is the latter one accepts HDMI input. ... |
H: incorrect voltage applied, dev board still worked
I took this guy from here - http://rlx.sk/en/accelerometer-gyro/3582-vibration-sensor-module-801s-er-sen801svs-.html and without noticing I have applied 3V3 instead of the advertised 5V to it. It also seemed to me it has worked fine. Can anyone tell me why it has st... |
H: MOSFET with Integrated Driver for Boost Converter
simulate this circuit – Schematic created using CircuitLab
Trying to build a boost converter using a PIC microcontroller with minimum number of external components. Was hoping to find an NMOS with integrated driver (dashed rectangle above) in a small surface mount... |
H: SDHC over SPI: OCR Register Reading 0x000000FF, nBusy bit 0 even after IN_IDLE_STATE clears to zero
Has anyone else enoucntered this problem before?
I'm using an STM32F105VC, SPI port 1 at a speed of either ~100kHz, ~200kHz and ~800kHz.
I've tried using a 16GB Sandisk microSDHC and a 2GB Transcend microSDSC both p... |
H: Testing an oscilloscope
This question is a bit related to an earlier question: Question
With my current scope (Philips PM 3253, 20 MHz 2 channels), I cannot measure the quality of edges from square waves from the test signal, because if I put the time to less than 1 ms, I either don't see anything or a straight lin... |
H: Digital voltage/current controller for DIY bench power supply
I'm trying to design a portable rechargeable bench power supply. I have a 12V sealed lead-acid battery (WP7.2-12) which I can use as the main power source. These batteries are cheap and easy to source, and have reasonable power output specifications.
I ... |
H: How to determine the nominal current of an LED?
I salvaged the LED disk from a defunct LED light bulb. (The problem was an arced transformer, the LEDs are intact.) It has several unmarked white SMD LEDs soldered on it: 5 lines parallel, with 3 LEDs in series on each line.
I want to use this disk in a strobe. My aim... |
H: Is current calculation in copper wire for AC simple or not?
I'm trying to learn electronics by myself, and I'm starting with simple current calculations. Let's assume we have a straight wire of length L connecting a source and a sink. I know the voltage (V), and for finding the current I need to apply Ohm's law:
$$... |
H: pulse response of opamp integrator
I was simulating the below opamp integrator circuit with pulse current.As this is an inverting integrator I thought it would integrate the input current and give me a triangular waveform.
But after simulation in PSpice I got the following result.
Can anyone explain why the curren... |
H: LC oscillator versus Kirchhoff's law for meshes
Analyzing the behavior of an LRC-circuit I got stuck on a seeming contradiction between the vector diagram of the circuit and Kirchhoff's law for meshes.
Please consider the circuit shown below and follow the description:
In its initial state, at t=0, the capacitor ... |
H: Beginner question about CPU clock
So I just started learning AVR and I am currently working with the ATMega328P. I have a question regarding the CPU clock. Currently I am using the 8MHz internal clock. Now I know that F_CPU tells the compiler what my clock speed is. The problem here is that the CLKDIV8 fuse is prog... |
H: Beginner PLC: Configure Ethernet/IP Connection
I am really new to PLCs programming, connecting, etc. I received a 1756-L72 with Logix5572 Processor and an EthernetIP card. My goal here is to connect it to my laptop along with another device (a Bar Code Reader). Both devices are connected to an unmanaged ethernet sw... |
H: Is 0603 vs 0402 assembly mass production cost optimization still relevant?
Historically, choosing a design avoiding 0402 and finer pitch components was advantageous for mass production cost savings. The yields were improved and accuracy requirements for pick and place machines were reduced. This allowed vendors to ... |
H: Op. Amp. read variation when Earth is connected with Signal GND
I've made this simple circuit to read the line voltage (the 1 pin is conected in a uC by a resistor):
In the image NEUTRO is Mains Neutral AC, FASE is Mains Line AC and TENSÃO is the signal to the uC (microcontroller).
The circuit worked very wel unti... |
H: How to make precise holes in Eagle
I need to create 3 circles in Layer 20 in eagle, of witch one should be in the center of my board and have a diameter of 10 mm and the other 2 should have a diameter of 4,8 mm. The two circles should be symmetrical spaced from the circle in the middle (the one that is 10 mm) and ... |
H: Rectifying diode for boost converter in nixie clock
I've been working on this schematic to create a nixie clock. But I don't understand the need for recifying diode D5 in the schematic. Wouldn't a standard diode work? Does it have to do with the "back emf" produced by the inductor?
AI: D5 is part of a high frequenc... |
H: KICAD PCB coil design related
My almost completed pcb design in KICAD requires a coil which needs to be accurate in dimension (coil is optimized using a optimization calculation algorithm developed in our lab which needs to be realized as is). If I draw using gui tools in KICAD, it is hard to make it accurate in te... |
H: Application of the Sampling Theorem to a System
I have the following system:
$$G(s)=\frac{1}{10s^{2}-5s+2}$$
that I want to discretize. How do I apply the sampling theorem to a system so I can choose the correct sampling period?
Furthermore if I use a wrong sampling frequency how can I demonstrate that there is som... |
H: Designing an LED Driver
I'm a beginner in electronics, and started the 2nd chapter of AoE, regarding transistors. I've decided to design my own LED driver, as mentioned on page 76 (3rd ed.)
simulate this circuit – Schematic created using CircuitLab
Some specs:
V1 = +3.3 [V], V2_LOW = 0 [V] , and V2_HIGH = +3.3 ... |
H: EEE-INST-002 Wire Derating - Single Wire vs. Bundle/Multi-Conductor
We have an aerospace application and are having trouble defining EEE-INST-002's current derating guidelines in regards to wire.
The issue that I have isn't about stranded versus solid. MIL-W-22759 does seem to classify tinned, copper strands as one... |
H: Transistor as switch and voltage drop
I've started studying basic electronics, and in this video I noticed he had a similar example as in my textbook: https://youtu.be/sTu3LwpF6XI?t=3m28s
Above is a screenshot if you don't bother to click on the link.
So, in essence.. when the switch is off, the LED to the right on... |
H: safety relays and PLCS
I am having trouble trying to get my head around using safety relays in PLC controlled machinery. I want to install a PLC into a machine that needs upgrading, it is straight forward enough, well i thought so until i ran into two safety relays im just not sure how or if i should tie them in to... |
H: Is it legit to use DC source with voltage regulator to create dual power supply for op-amp?
My op-amp needs +12V and -12V voltage supply. I have only one DC source which can output 24V (I can use simple voltage divider to get +12V). I also have one voltage regulator. Is my approach above correct?
AI: If you're a l... |
H: 7 position switch, only one position active at a time?
I am wiring a 6 channel camera switcher (http://www.brandmotion.com/360-vision/blind-spot/6-way-video-switcher-9002-6118.html)
And in addition to the automatic triggers (there are 6 trigger wires, when one receives 12v, it switches to that camera) I want to add... |
H: Capacitor plates; smooth or rough?
I am building an aluminium capacitor for fun and it got me thinking. Is it better for the plates on a capacitor to be rough or smooth?
My thinking is that it is better for the surface to be rough as it increases the surface area? I think that is why the carbon nano-tube super-cap... |
H: What would "push to open" mean in the context of this switch?
I'm not an electrician, but I have a basic understanding of circuits
I had bought a switch that was labeled NC, and when it was unpressed, the light connected to the switch turned on
When it was pressed, it turned off the light
I'm looking at this produc... |
H: Why modern cellphones do not have an externally visible antenna?
Old phones had either a fixed antenna inside a housing which was externally visible, or a retractable antenna, which was visible when used. I'm assuming this was needed to obtain a certain total length.
In modern cellphones all the antennas are inside... |
H: Power Supply (220vac to 5v dc/2A)
I'm designing a power supply for a smart switch project which requires a 5v dc/2A supply for usb charger and 12V dc for relay operation. is there any way i could do that? my input is 220ac, which will be rectified to 310(approx) dc. any suggestion will be much appreciated. Thanks
A... |
H: Maximum current draw from 12v sealed lead acid battery?
I am currently building a "battery box", for camping, and kayaking, etc. It has a few different features on it, such as a 150W inverter, a 48W spotlight, 12V accessory outlet, and strobe lights. The inverter and the spotlight seem to draw quite a bit of power,... |
H: How overvoltaging makes graphic processing unit operate faster?
My teacher told me that we are trying to make transistors smaller so that they require less electricity to operate, hence make them faster (because changing form 1 signal to 0 or vice versa need less energy, or so he said). Meanwhile, cryptocurrency mi... |
H: Multi-emitter transistor: does the transistor turn on per-emitter or as a whole?
In a multi-emitter transistor (like in TTL ICs), does the transistor switch on and conduct through the emitters independently or together? That is, if there's a base current through emitter \$E_1\$, does this result in collector curren... |
H: Can a rocker switch with two positions be an SPDT?
I have rocker switches that look very similar to this:
In my current understanding, a 2-positions rocker is meant to be an SPST, and a 3-positions rocker (see below) is meant to be an SPDT:
From this source, I find the following image showing an SPST rocker switc... |
H: A problem with charging
I am beginner in this field. I made a charger with 7805, 10 uF, 100 uF, 100 nF capacitors and 9 V non-chargeable + 3 V rechargeable batteries. The output current is 0.6 A (I used battery instead of solar panel in picture).
And the phone charges but it is hanging on previous percentage. What... |
H: Powering LED strips with 5v power supply - safety question
I am making an LED strip installation. I will be using 15 meters of APA102 LEDs. They require constant voltage, I believe. https://cdn-shop.adafruit.com/datasheets/APA102.pdf
I calculated that I need 23.4A at 5v, or around 120w. Adding 20% for safety, I... |
H: Why laptop reboots after electrostatic discharge
So why does this happens when my laptop is plugged to the charger? Typical charger scheme looks like this:
What is the path for discharge current? Low voltage part seems to be isolated from power lines.
Some forums says that the reason the laptop was not connected ... |
H: Snubber Circuit working
How does snubber circuit work in phase control circuit of Single Phase AC Motor? I have tried to know the causes but I was confused with RC circuit function with this phase control circuit.
AI: Very simply, the snubber provides a load to dissipate energy from rapid changes in voltage associa... |
H: Intermediate frequency
I'm a newbie to communication systems and circuitry. I was going through superhet receivers while trying to undertand AM/FM/DAB receiver architecture. For FM, IF is fixed to 10.7 MHz and AM 455 KHz. Once the carrier wave is shifted to this IF frequency, it is amplified and filtered. In DAB, i... |
H: Modbus c terminal
I have to communicate with a device. There are A,B,C Terminals.
A and B are standard. But What is The C Terminal? Is it ground?
AI: "C" is usually ground in RS485 configurations that need ground: -
And, given that MODBUS uses (or can use) RS485: -
I suspect "C" means ground for MODBUS too. I don... |
H: How to Estimate Power to Ground Current?
I need to automate a power to ground test for a device which outputs 12V / 30A.
There is a .4 ohm resistive load connected to the device which it is driving, however if I remove that load and go straight to ground, the current will be much larger.
I = V/0 = Infinity
Of cou... |
H: Problem with MAX756 Boost converter
I'm using MAX756 as a DC-DC boost converter to provide 3.3V from of a single 1.5 AA battery. I've implemented the circuit on page 1 of datasheet with 1N5819 instead of 1N5817 and 144uF caps between Vin and Gnd instead of 150uF. Also Vin comes from bench power supply.
I've teste... |
H: Need help to calculate a proper fuse for a 19v transformer
I've successfully installed my Ring Door Bell Pro yesterday.
Ring Door Bell Pro integrates with an existing door chime. I used a voltmeter and confirmed the transformer's output voltage is 19 V AC.
Due to the Ring Door Bell Pro size, my installation at th... |
H: Why are there no 256-bit or 512-bit microprocessors?
In an 8-bit microprocessor its data bus consists of 8 data lines. In a 16-bit microprocessor its data bus consists of 16 data lines and so on.
Why is there neither a 256-bit microprocessor nor a 512-bit microprocessor? Why don't they simply increase the number ... |
H: 20 Amp automotive thermatic fan PWM controller
I have an older car which tends to over heat in the summer, so a 20 Amp electric fan was added in front of the radiator. Currently its driven by a on / off relay.
I want to build an Arduino PWM controller but I am not confident switching that much current especially in... |
H: How do you resize a part in PSpice?
I have a number of parts that I want to re-size so as to fit on paper. How would you resize a part?
AI: Ah you can't really re-size a part unless you open up the part itself and move some pins around and redraw it to be smaller. I assume you were wanting to scale it instead of ... |
H: Driving PWM lights with parallel darlington arrays
I am building some service light arrays, which I want to operate using the Arduino's PWM outputs.
This lighting is going to be powered by 5V OR 12V with a nominal current of 700mA per array. There will be 4 arrays total.
Elsewhere in my design I am using ULN2803s... |
H: 18f4550 comm clarification and advice
Please excuse my ignorance. I need your advise and clarification on something. I'm using the 18f4550 and I'm a little curious about the communication protocols. I am not using the USB features. It has 1-EUSART, and 1 (SPI/I2C) comm. My question is, the EUSART and SPI seem ... |
H: What difference does it make to an appliance whether the supply is sinusoidal, or any other shape?
Just what the title states.
I understand some appliance/s may be damaged if the supply is any shape other than sinusoidal. E.g. sawtooth, square ...
Why is this the case? How does the shape of the supply signal matter... |
H: How to go from a development board to a production board?
Ok, I am a software guy and new to electronics. My product needs a small computer and currently I have developed everything on development boards like raspberry pi and such. As the development board does not have all the hardware that I need, I have added th... |
H: Easier-to-machine alternative to pogo pins?
My project has a rectangular 5 x 6 grid, 1mm pitch pin header. Unfortunately, it needs to be cycled by the user over 300 times!
We've looked at pogo pins, because of the high cycle count, but the three moving parts per pin and the tiny size of the precision spring makes p... |
H: Directional pickup of human ear?
Given the following:
x, y, z of omnidirectional source source
x, y, z of center of listener's head
pitch, roll, yaw of head
What is a simple fuction that will return the decibel attenuation and the delay of the left and right ears' perception of this source?
AI: The accurate funct... |
H: Measuring distance at angle
I have a question, I want to measure a distance from an object of unknown shape and material, and I want to measure it under different angles, I want to measure a distance to just one specific point of object and accuracy has to be good.
Can someone please point me to right direction?
AI... |
H: Why do many electronics operate on 5 and 3.3 volts?
Many modern appliances use a 5V power connection, but internally they work with 3.3V. Wouldn't it be easier to have 5V everywhere?
Examples are many USB devices or routers (they use 5V for power but 3.3V for serial communication.)
AI: 5 V became much used in early... |
H: Can I use 16V power adapter for scanners that need 12V?
Possible Duplicate:
Choosing power supply, how to get the voltage and current ratings?
Will they be damaged? The two HP deskjet 2400 and 4300C scanners need 12V, 1.25A as I read. I only have a 16V, 3.36A power adapter with the connector they require.
Will I... |
H: Microphone replacement
I have a device containing an active mic, an amplifier, and an AD converter. I would like to swap the microphone with another completely different mic. I have no tech specs on the microphone that I'm replacing. Would it be a good idea measure the voltage output of the original mic in response... |
H: What is wrong with this MSP430 code?
I am using the MSP-EXP430F5438 evaluation board, which has pushbuttons connected to P2.6 and P2.7 and LEDs connected to P1.0 and P1.1.
I want to make it such that P2.6 sets the LEDs on and P2.7 resets them. To do that, I wrote the following code:
#include "msp430x54x.h"
int ma... |
H: MOSFET or bipolar to drive a solenoid valve?
I have to drive a 12V solenoid valve. In the datasheet it's written: Power: 8 W. So the current drawn by the solenoid is 0.666 A.
Usually, to drive small relay (about 10 or 20 mA) I use a bipolar transistor but with this kind of current is it possible? Or do I have to us... |
H: Resettable latching switches
I don't know if self-contained units like this exist, but I'd like to think they do, and I just don't know what they're called, who makes them, or where to find them.
Please bear with me, for a moment. Imagine a lamp, a simple On/Off latching switch, and a battery connected in series.... |
H: Square wave / Sine wave is more audible
Consider you have 50 Hz both square wave as well as sine wave put on to a same speaker at different time. Which signal is more audible and what is the reason behind that ?
We know that by taking the Fourier series of the square wave we get multiple periodic sinusoidal wave, ... |
H: Replace UM 66 IC
I'm trying to build a circuit of a Doorbell, but it's very hard to find ICs from local stores.
I didn't find UM 66. So, someone told me to look for:
3481 series
HT3820
4822
AM993-9A
Neither of them was found, also.
So my question is:
What other ICs could I possibly use in this circuit?
Also, is... |
H: Purpose of these two transistors
Hi does anybody know what's the purpose of the Q1 and Q2 transistors,
sounds to me like they are constant current sources. Am I wrong?
Could somebody explain me the purpose of those Q1 and Q2 transistor
configuration there?
Note, This is a simple preamp circuit.
AI: They act like ... |
H: What do I need for a basic RF circuit?
I'm looking for any resource that can help me build a very very basic RC circuit. I'm talking as simple as using RF to turn on/off an LED. The purpose of this circuit is for research and education. If anyone knows where I can get parts for simple RF circuits or even a tutorial... |
H: Interfacing microcontroller with 1.8V logic
I am in the process of selecting a microcontroller to interface (~30 signal lines) to an FPGA that operates at 1.8V voltage levels.
I have found NXP's Cortex M0's to operate down to 1.8V which is great, but the bulk of Cortex M3 chips out there have a minimum operating vo... |
H: Getting 3.3 (V) from a 5(V) rail - Emitter Follower, or something else?
I am using a Bluetooth module (RN-41 SM) that is spec'd to run at 3.3(V).
I can operate this module at 5(V) however, due to another part of the circuit, I need to run the micro controller at 5(V)
The issue I have is that the only rail I have av... |
H: Need chargeable momentary 15 watt regulated voltage source
I'm working on a RF telemetry side-project that requires an amplifier IC to be run for about 5 seconds bursts between charges. The system is portable and runs off of a 3.3V battery that can supply about 100 mA. The IC runs at 10V and draws 1.5 Amps, so 15 W... |
H: Fixing/Replacing Conductor Ribbon Cable
I tried to fix a keyboard that was having some intermittent issues by cleaning the conductors on the ribbon cable. I used an emery-board to rub off the rust and patina on the pins at the end of the ribbon, but it turns out that the pins are really soft metal and I ended up ru... |
H: How is this design for a basic PCB pick and place?
I have zero experience with any serious mechanical design, but out of necessity and curiosity, I'm attempting to build a pick and place machine (for my hobby projects as well as low-volume PCB production) -- but a very basic version of it, customized to my own typi... |
H: Leaving a RC servo motor idle for long term?
I've been searching for awhile and can't find an answer so hopefully someone here can help me :)
I just want to know if leaving a servo motor idle, powered but no input, is bad for it? I'm planning on leaving a servo motor powered indefinitely and only sending it a signa... |
H: interfacing MMA7361L with PIC ADC
I'm trying to interface an mma7361L accelerometer (on breakout board with caps) to the analog inputs of an 18f46k20. According to the PIC datasheet, the Vmax input voltage is Vdd + 0.3 which means I have to get the signal between 0V - 3.6V.
I only need to measure the Z-axis an... |
H: Watchdog Signature in Flash memory or RAM?
We used to use Watchdog signatures in our control applications.
Basically we used to allocate a reserved memory in RAM(uninitialized) and used to store the watchdog signatures.
On power on, the system checks for the watchdog signature and based on that we used to find out... |
H: Reviewing an AC dimmer - trying to understand
I'm apology if the title is kinda generic but I found a (on a AC) which use IC and a triac and there is some points I don't really get.
Image from this application note:
Datasheet used as reference.
About the PTA0 pin :
How can the pin accept 120v since the range of... |
H: Emulate many-pole, dual throw switch with transistors
How can I use transistors and other discrete components to make a circuit that functions like a DPDT (double pole double throw) switch, and can be extended for any number of poles required? For examples assume an input voltage of 12VDC, required current of 200mA... |
H: Fabricating control panels
Electronic projects that aren't in a box are fragile. I have a project completing soon that has a reasonably complex control layout. It's going to need some manner of control panel that includes plenty of writing and has different sections.
I can think of a few options:
Get a panel eng... |
H: Low voltage oscillator for joule thief
I have a transformer with 2 input leads and 3 output leads. I hooked up an LED to 2 of the output and put a dead AA battery on the input and the LED blinked for a second. I have no data on the transformer, but I am wondering if it is possible (and if so what is the schematic o... |
H: What limits the modulation of digital signals?
I am trying to understand why there are different speed on different frequency bands. I see that e.g. ZigBee can do 250kb/s for both 2.4GHz and 868/915MHz, but WiFi are also 2.4GHz with much larger speeds, why are they different? How come 2.4GHz is so slow for ZigBee a... |
H: How do I use an Arduino to switch another IC's pin (reset) to ground?
I'm a releative newbie. I'm using an Arduino to control a Cowlacious audio board that uses the ISD1700 chipcorder series of chips. Periodically, I need to pull the reset pin on the chipcorder to ground to reset it to it's original state. It se... |
H: emi standards/best practices for PC cases
According to an EE friend, the FCC specifies EMI tolerances (max outputs) for PC components, including cases. However, here it says that there are standards for a number of components but not cases.
1) Am I understanding correctly that there are no requirements for cases?
2... |
H: Use 3.5V power LED connection on motherboard to control a 12V lighting accessory in a computer case?
Background for the problem:
I rebuilt my computer in a new case where the components fit a bit better. Everything is great, and I have no issues with it. However, because of the way they engineered the front panel L... |
H: How do I choose my optocoupler to drive a solenoid with a MOSFET?
I need to drive a solenoid with a MOSFET. The solenoid is an 8W solenoid and it will be connected to a +12V voltage.
And this drive command have to be isolated with an optocoupler but I don't know how to choose it.
What characteristics do I need to ... |
H: Single-phase to 3-phase conversion
I have seen some boxes (with some capacitor circuits inside) which do single-phase power supply to 3-phase power supply conversion. The problem with them is that they cause the load motor to heat up, because the phase difference between the legs is 90 degrees instead of 120 degree... |
H: How does a TFT panel work?
I have to use a TFT panel but I have never used any before and I really can't get how it works and how I can interface it with a microcontroller.
I found INT057ATFT which seems to have an integrated TFT controller so I guess I just interface it with the 8080 interface of my microcontrolle... |
H: Protection of ADC inputs
I am using an ADC MCP3424.
After breaking one of the ADC inputs, I was saw this thread:
ADC input protection?
I also read Microchip app note TB3013. Figure 3 in particular:
The ADC's analog inputs need to be clamped at ± 0.3V of the supply rails.
The Vf of a schottky like BAT85 depends on ... |
H: How do I protect power out connector from having power in connected to it?
I'm building an adapter for rotary encoder that reads input of encoder and sends pulses by RS485. I'm using two RJ-45 connectors to provide power both for adapter and encoder. Both connectors have the same pinout. The right side connector r... |
H: How to improve torque and RPM of a DC motor?
I have an FA-130 motor (DC) with permanent magnet, my power source is a 2 AA batteries (rechargeable) so a total of 2.4v.
Assume that all cases will start from the same specification, theoretically, what would happen if I do the following?
Case 1: Increase/Decrease stren... |
H: Laptop charger with broken ground prong
I have an old house (1927) that has been completely renovated, but all the plugs in the living room are 2 pronged. I have a charger that had the ground prong broken off. I want to know if it's bad on my laptop or if it's a fire danger to my house. One I'm willing to risk, ... |
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