2
votes
1answer
20 views

Could use some help on what should be a simple LED wiring scenario

First off, I'm new here - found this site while researching to figure out why my circuit isn't working as I expected. I appreciate any help you can provide... The picture is the wiring diagram for ...
0
votes
1answer
14 views

help with QT1070

I am using AT42QT1070 touch IC in comms mode with I2C communication.I have used 10k pullups with SDA and SCL line and 47k pullup with CHANGE line(active low) as mentioned in datasheet. The CHANGE ...
3
votes
3answers
34 views

What does the “phase margin” parameter of an opamp imply?

I was reading datasheet of MCP6072. I saw a parameter namely "phase margin" (table 1-2, page 4). As far as I know, "phase margin" is a control engineering term, and implies the phase difference ...
0
votes
1answer
17 views

Power supply noise caused by external heat pad

I have a circuit that switches a 50W Sunbeam heating pad via a relay (for regulating temperature). My circuit is driven by a 5v AC/DC switching converter. The AC input to the power converter is shared ...
1
vote
0answers
27 views

NPN BJT Relay Circuit will not turn off

I'm applying a 3.3V signal with my Raspberry Pi to the base of an NPN transistor to activate a SPDT 6V relay (relay data sheet, model G2R-1-S-DC6(S)). The relay pickup/dropoff voltage is 4.4/0.9V. ...
0
votes
1answer
12 views

What is the ALS and BLS pin for on the ISL83204A full-bridge driver chip?

The datasheet for the ISL83204A full-bridge driver chip documents "low sense" pins that connect to the source of the bottom N-channel MOSFETs. As those are typically connected to ground, what is the ...
0
votes
3answers
32 views

Circuit for a DC motor with 2 microswitches reversing direction

So here is what I am trying to do... have a DC motor wired to an on/off switch and 2 microswitches. Each switch will reverse the direction of the motor, so one switch tells the motor to go forward, ...
1
vote
1answer
20 views

How do I direct input/output to correct circuit module. (2 bit calculator circuit)

I am designing a 2-bit four function calculator. With separate modules for division, multiplication and add/subtract. Subtraction is performed by adding 2’s complement to input. So I have 3 modules. ...
0
votes
1answer
36 views

Identifying DC electrical power connector

I have here a PowerFilm 10 Watt F15-600 Solar Panel, and attached to the panel is this connector: The male end attached to the panel has a little green rubber gasket on it and the female end ...
0
votes
1answer
20 views

Find four current mesh

I have to find the 4 current mesh in this circuit V1= 12V R1= 1/12Ω R2= 1Ω R3= 1/3Ω I1= 6A R4= 1/3Ω R5= 1/2Ω R6= 1/13Ω I2= 6A I tried a source transformation and got this I3= 144V R1-2= ...
0
votes
2answers
21 views

Conductance in a transmission line

I'm just trying to clarify the transmission line concepts in my head. Now wikipedia (that great source of always reliable information) defines the conductance in the transmission line as ...
-1
votes
1answer
42 views

Is it possible to increase voltage without changing the current?

If we have a certain power applied to a circuit, and we would only like to increase the voltage applied by large factors... can this be done? Maybe by increasing only the resistance? Or maybe by ...
2
votes
2answers
40 views

Using a motor as a generator: How fast does it need to rotate?

I have a dc motor with the following specifications: ...
1
vote
3answers
23 views

Biasing resistors for RS485

I know I should have a terminating resistor but do I need biasing resistors on the +/- lines of an RS485 differential signal?
1
vote
4answers
26 views

Current limiter for NiMH battery charger

I am trying to learn about electronics by making my own MCU controlled battery charger for standard AA 1.2V NiMH and NiCd batteries. The supply voltage is 5V from a USB battery pack. I did a lot of ...
0
votes
1answer
16 views

Simple sound pulse (or frequency) to voltage for switch

I am building a tiny project using an android phone -- it simply has to drive a transistor switch on and off. Instead of going down the route of trying to interface to a micro controller via ...
0
votes
0answers
42 views

PC as USB Target? [on hold]

I would like to experiment with creating novel devices that act as USB targets. I want to start by using an existing old-PC to prototype my software. are there PCI boards that I can install into an ...
1
vote
1answer
32 views

Supply voltage of stepper motors

I'm going to use the following stepper motor drive chip: http://www.st.com/web/en/resource/technical/document/datasheet/CD00255075.pdf And I have choosen the following AC/DC converter: ...
2
votes
3answers
76 views

PCB design consideration for a SMA antenna

I am designing a PCB with the transceiver SX1231 (868MHz) with a SMA connector for the antenna. I don't know much about antennas. I would like to know if there is some parameters I need to be careful ...
0
votes
0answers
5 views

Could a missing segment of a fan result in hardware failure [migrated]

I'm using an example that I have just encountered, but it involves a more general question regarding computer hardware and airflow. For some reason my NVIDIA 9800 GT fried, I've actually no idea why. ...
0
votes
0answers
32 views

How to deal with asymmetrical slew rate in 2-stage op-amp?

I made sure to take slew rate into account when designing this op-amp, but the slew-rate appears to be asymmetrical, as apparently the fall time is much slower than the rise time. How do I rectify ...
2
votes
0answers
50 views

Faradays Law: How Does Curl E Change Over Time In a Coil? [migrated]

I think I am currently making a mistake regarding my interpretation of Faraday's Law. \$\vec{\nabla}\times\vec{E}=-\frac{\partial\vec{B}}{\partial t}\$ Assuming we have an electric field \$\vec{E}\$ ...
0
votes
2answers
60 views

What is the difference between Vss and Vs?

I know the difference between Vdd and Vcc and all the other ones,but I cant figure this out? Whats the difference between Vss and Vs?
0
votes
1answer
35 views

What is each pin's output voltage of an ATmega328P?

I would like to operate an ATmega328P in 3.3V supply alongside some other 3.3V non-5V-tolerant-peripherals. I looked up in the datasheet but I couldn't find an answer as to what is the output voltage ...
0
votes
1answer
31 views

Arduino Serial connection

I've written a small program for Arduino, in which it receives a two digit number from serial, for example ""26". Then it set's HIGH voltage to pin 2 with the duration of 6*100. That works fine, ...
1
vote
1answer
57 views

Battery chargers that can recharge disposable batteries. How do they work and are they safe?

A few years ago a product called SecondWind appeared, which claimed that it could recharge disposable batteries. To a layman like me that sounded like a great idea, but does such a product really ...
0
votes
2answers
34 views

L293D Problem- cant run both motors together

I am making rf based metal detecting robo and i had used 8051 for controlling the operation. The rf is fine and programming is also i think okay as i am getting desired outputs at 8051 output pins and ...
0
votes
2answers
62 views

How to choose optimum length for op-amp design?

I've heard that minimum length is discouraged in analog design due to matching problem but what's the drawback of using very long transistors apart from the size and resistance? Based on the ...
0
votes
1answer
61 views

How these circuit diagrams in the datasheet was made? [on hold]

I've seen so many IC datasheets, and so appreciate the elegant reference circuit diagrams they've made. I'm not meaning the 'function' of the circuit, but the 'beautiful' schematics itself, such as ...
-1
votes
3answers
65 views

how much time it will take to charge a 48v 35amphr battery using a solar panel of 20w

please help me out with this problem.I have tried several sites , but i didnt get a specipic method.please kindly include formulas used also.
0
votes
2answers
34 views

Testing a transformer

I have a 3-phase transformer with primary and secondary windings both star(neutral connected). When connected to 3-phase source whose line volts is 415V, I got the following readings at secondary ...
1
vote
1answer
32 views

Loss of speed on error-free aDSL line [on hold]

Is there such a thing as an old telephone line? Does a POTS cable deteriorate over time? I am talking about lines in area where no one lived 75 years ago. Sometimes a customer using an asymmetric DSL ...
1
vote
1answer
42 views

AVR SPI slave with interrupt

For a project I want to have two microcontrollers talk to each other via an SPI interface. I wrote the following code for the slave: ...
1
vote
0answers
24 views

Circuit with coupled inductors, need help with mesh equations

Are the mesh eqations in the image below correct? It gets a little tricky with the mutual inductance and my textbook gives no solution (American textbooks..). Click the image below for a larger view. ...
0
votes
2answers
77 views

How this circuit works?

Recently, i see such a circuit in a board schematic, but can't figure out how it works, why the first Op Amp has positive feedback ???? Thanks.
0
votes
1answer
40 views

doubt about using both watchdog timers in pic

I want to use the conventional WDT and deep sleep WDT. I will be using WDT to prevent any code lock cases if any. And the other after entering deep sleep mode.? My question is whether the WDT ...
1
vote
1answer
51 views

Aluminum winding in inverters

I am planning to buy inverter. I finalized one model; however, I was told that it uses aluminum windings whereas the other model has copper windings. They recomended I should buy the one with copper ...
1
vote
1answer
28 views

Q3.24 (d) Signals & Systems 2ed by A. Oppenheim

3.24 (d) Determine the Fourier series representation for the following signal: a_k = 1 (k is even), 2 (k is odd) The solution (see attached) breaks down the answer to two components: y(t) and z(t). ...
1
vote
0answers
27 views

Communication between FPGA and OMAP 3530 using GPMC

I am working on a project which requires communication of data between Xilinx Spartan 6 FPGA (XC6SLX45T-2FGG484) and OMAP 3530, I have a ULK dev board on which The 32Kx8 (256Kbits) serial ...
6
votes
3answers
406 views

What is Overmodulation?

The Wikipedia article is very short and doesn't explain the concept very well, and there aren't any other sites that I can find that give a simple explanation. What does it mean by 100% modulation? I ...
1
vote
2answers
49 views

Help understanding switching voltage regulator (OKR-T/1.5-W12-C)

Looks like I need help understanding how to use the OKR-T/1.5-W12-C DC/DC voltage converter, b/c I just burned two of them. I am obviously doing something wrong, but I don't understand what. Here's ...
0
votes
1answer
36 views

Any good resource for MOSFET op-amp design? [on hold]

I've been trying to design a two-stage op-amp for a week, but I haven't been progressing much. Does anyone know good resources that teach you how to design an op-amp (transistor level), preferably ...
0
votes
1answer
30 views

Meaning of control pins: CE, OE, WE

Just understanding some syntax. On my Ram (6116) and Rom (27C64) it has a asserted low CE and OE pins. These I believe are control pins. I'm assuming to use the RAM for example, chip enable (CE) has ...
1
vote
1answer
58 views

Scrapping conponents from an iphone

I have an iphone 4 that no longer works. I know that selling it is always an option, but i'm curious if i can scrap spare parts from it instead (especially sensors). I've looked online, but haven't ...
1
vote
2answers
66 views

Is an AB amplifier feedback like this (image inside) possible?

Whole question in the title, don't know what more information is possible: Is an AB amplifier feedback like this possible?
0
votes
2answers
49 views

Transistor for 4-20 mA voltage drop resistor connection?

This is for converting a 4-20 mA current loop signal to a voltage. Is it okay to connect the resistor for measuring voltage drop with a transistor to allow for switching between voltage and current ...
0
votes
0answers
53 views

8x40 led matrix [on hold]

I am building an 8x40 led matrix for a project and have run into some trouble coding. I have been using an arduino and I cant seem to get the code to run properly. I have been to several other sites ...
2
votes
0answers
46 views

How do you calculate ICMR?

Let's say the Vdsat = 0.2V for M1 to M4, but 0.5V for M5. VT is 0.5. I think it's: ...
5
votes
1answer
483 views

What does “OC” mean?

My Bluegiga WT-32 manual ("Stereo CODEC ADC characteristics" table) says: Allowed Load --> Resistive, min.:16(8)Ω , max.: OC What does OC mean in this case?
0
votes
1answer
48 views

2.4GHZ US Wireless Device in EU [on hold]

I want to buy the Fishman Triple Play (a 2.4Ghz wireless guitar hex to MIDI pickup) and there are two versions, the US one and the EU/UK one. The US one is loads cheaper and I live in Malta (Europe) ...

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