0
votes
0answers
11 views

Easy circuit question

Find the current IA in the circuit in Figure: http://i.stack.imgur.com/AcydV.png so far I have started the problem by combing the 1kohm and 2 kohm to create a 2/3 resistance. I am currently stuck ...
0
votes
1answer
10 views

Understanding pull-up resistors and the 7489 memory chip

I have been learning about the 7489 memory chip. I had two of these that turned out to be broken (see here for previous question on this). I got more and I have finally gotten everything to work. ...
2
votes
3answers
25 views

Are there any open / unrestricted radio frequencies that are free for any use?

The only 'free radio frequency' that I could think of are the HAM radio bands. But they really aren't free, for they are regulated by laws that require you to hold a license, restrict what purpose you ...
0
votes
0answers
20 views

Transistor behavior in Current Limiting Circuit

I have a circuit that I think will work, but I am worried that if I am overlooking or misunderstanding something about transistors in current limiting applications. The following is nothing original. ...
1
vote
3answers
18 views

What are the underlying physical principles of a constant current power source?

I´m currently looking for a led driver to drive a 34,25 W High-Power LED at 38.06 V / 900 mA. Browsing trough various online shops i found a constant current source and i don`t get how it works. The ...
0
votes
1answer
11 views

Semiconductor Experiments and Theory Textbook Recommendation

What are good textbooks that talk about semiconductor theory and the experiments that support the theory? Experiments that agree with both the conclusions of semiconductor theory, and with the ...
0
votes
0answers
9 views

8051 Microcontrollers question about TH0/TLO flag values

Welcome all, I know, that i'm in a right place to ask about something which is related to microcontrolers programming area. I'd like to know how can I calculate TL0 values. For example, when we have ...
0
votes
2answers
16 views

Dual output with Center Tap transformer

I have a transformer with dual input 115v and dual output 9v and rating power 1.15va. My goal is to connect it in parallel to produce single input 115v, single output 9v and rating power 2.3va. The ...
-2
votes
1answer
21 views

Bundle phone lines to create one cable

Could the phone company use its bundled pairs to create a single wire like Cable and run everything over it instead of using them for individual lines? I know they would have to change out there ...
0
votes
0answers
15 views

How to pick good LED modules among the many low quality ones?

I would like to build a replacement for a 300W halogen using multiple LEDs. Using the rule 4:1 to be safe (75 lm/W vs 19 lm/W), I need a total LED power of 75W, that means two or three 100W LED ...
-1
votes
1answer
13 views

Compare numbers using flag registers

Suppose I have a four bit number. How Will I check whether the number is greater than or equal to zero logically by using flag registers? I can check if the number is equal to zero or not by Or ing ...
1
vote
4answers
63 views

Lower than 0.7-0.6V voltage drop on sillicon diodes

I am trying to understand how voltage drop happens. From what I know, there should be about 0.7-0.6V drop across a silicon diode. This is exactly what happens when I remove the LED from this ...
0
votes
1answer
21 views

Interfacing to a Microprocessor Bus without an 8255

There are 32 doors in a building each having a sensor attached with it. Each door outputs a signal 1 if it is open and O if closed. I want to design a pc based system to display the condition of each ...
1
vote
2answers
28 views

Measurement of power dissipation in a resistance

In the above figure (step up transformer), We can calculate \$V_s\$ using \$\frac{V_s}{V_p}=\frac{N_s}{N_p}\$ and \$V_s=50 V\$ So, power dissipated in the resistance, \$P=\frac{V_s^2}{R}=2500 W\$ ...
1
vote
2answers
47 views

Designing a 8 bit ALU

I have started designing a 4 bit Arithmetic and logic unit. The sample image is as follows: The function Table: My question is: Is it possible to design an 8 bit ALU having the same ...
-1
votes
0answers
60 views

adc connected to dac [on hold]

I wish to connect adc directly to dac so that I can transmit audio as digital pulse's , I thus bought these (Analog RCA L/R Audio Converter Adapter to Digital Optical Coaxial Toslink) AND (Digital ...
-4
votes
0answers
35 views

bulk micromachining Question [on hold]

Could anyone give me any hint on how to answer this question?
-1
votes
1answer
30 views

Two-port circuit analysis. Voltage gain

I am trying to find the general equations for the voltage gain(Not sure if it is the write word for it). My textbook offers an derived equation but not the procedure. I would appreciate it if ...
1
vote
4answers
58 views

Advantages of filtering signals using analog or digital methods?

In my understanding, it seems that there are, broadly speaking, two primary ways in which signals are filtered for analysis by computers, which are software-side filters and hardware-side filters ...
0
votes
0answers
50 views

What is an appropriate switch for usage in a residential, low-voltage, DC lighting system? [on hold]

I'm in the process of designing a 24VDC LED lighting system for a small 600sqft cabin. The biggest issue I'm having is that I can't seem to find any residential light switches rated for 24VDC. ...
-6
votes
0answers
19 views

Relationship between two Alternators with different frequencies and different voltages [on hold]

A detailed relationship between two alternators having different frequencies and different voltages, with mathematical equations to support.
6
votes
2answers
33 views

Using the ST-LINK Utility to configure the RTC to current time

What I was doing I am using a STM32 microcontroller and for my project I need to be able to send data at specific times of the day (say, at 11am and 2pm). The microcontroller needs to know what time ...
-5
votes
0answers
30 views

DC motor not working

My circuit is not working as expected. Only one motor is working. Every element is well soldered and well connected except one of the resistors and replaced it with a different resistance. So does it ...
0
votes
1answer
13 views

In HDB3, does a 1 have opposite polarity to the last 1, or to the last V?

I am trying to understand HDB3, and in particular trying to find out whether the picture below which shows the encoding of a bitstring in HDB3 is correct or not: From what I understand, a ...
0
votes
1answer
36 views

Externally controlled RFID Tag

I have a project requirement to use open protocol RFID tags to control doors handling of a light rail train (also called a tram in Europe). The application must sync and control 2 different doors: one ...
0
votes
4answers
68 views

Where do these grounding wires go?

In the following schematic the two Vss pins where are supposed to be the grounding pins don't connect to anything. Does this mean that the circuit is self-grounding (if that's even a thing)? I'm ...
1
vote
4answers
62 views

What is the schematic symbol for resettable fuses?

I have seen symbols for one shot fuses and circuit breakers, but not for resettable fuses that reset themselves when the fault goes away. What is the recommendation of the symbol to use?
0
votes
1answer
24 views

Intermediate Frequency in transceiver?

When I learn the transmitter and receiver architecture? They have each own heterondyne architecture they use intermediate frequency to upconvert to higher frequency or downconvert to lower frequency? ...
1
vote
1answer
25 views

Measuring RF and heterodyned frequencies

I have a question about RF measurement techniques. The partial schematic above is the front end of an AM radio receiver kit. I have assembled the kit. The kit manual states, Transistor Q7 not ...
0
votes
0answers
26 views

question on “Intercom” circuit I am planing to build

I am using Voice Record Module to save messages and then play them to one from selected outputs ...some kind of weird intercom system. My OA is LM386 [can only do 2 links but I'll post image relevant ...
0
votes
2answers
40 views

What does J1, J2 and J3 represent on a Schematic?

I'm looking at this schematic for the TSL1401 line scan camera module and trying to understand what the various pins do. I understand what the labels SI, CLK, AO and Vdd mean but I'm totally lost when ...
-2
votes
0answers
23 views

Value and type of unidentified Diode [on hold]

I need to know the value of a component for a PLC monitoring ckt. Please help me.
-1
votes
1answer
49 views

SCR drop voltage

unfortunately there is a voltage drop for the SCR , as I used an opto with a single SCR , when I checked the open anode cathode voltage without any load it was about 5V instead of 12 volts, when I add ...
0
votes
0answers
20 views

Convert byte by byte CRC-15 to table driven

I am attempting to convert a byte by byte CRC to a table driven method for speed, and am having issues with that. The provided information for the CRC is: Polynomial (\$x^{15} + x^{14} + x^{10} + ...
-1
votes
0answers
27 views

variable dual contact circuit needed [on hold]

Looking for a circuit that will toggle between 2 switches using a potentiometer. I've found similar circuits for video game (called "auto-fire" or "autofire" circuits), but that only involves 1 ...
0
votes
1answer
36 views

How to match impedance when driving 75ohm differential video amp with single ended RS-170 video output?

I am trying to feed RS-170 video signal from a single ended amp to a differential 75 ohms video amp. When I connected RS-170 signal to + of the differential and RS-170 return to - of differential, ...
-7
votes
0answers
49 views

Programming an electric meter based on 8086(asm) [on hold]

I need to write a program for this schematic, but my assembler skill is bad. Can somebody give me any tips? I read emu8086's tutorial, but still I cant figure out what to write. It is needed for my ...
1
vote
1answer
59 views

MPLAB 8.9 won't launch

I am running windows 7 professional 64-bit and up until this week was running MPLAB 8.92 IDE. Now I get a brief look at the splash screen and the IDE refuses to launch. I downloaded and ran the ...
0
votes
1answer
68 views

Why we can't use AHB in the Cortex M0 MCU?

I found coretex M0 MCU module's bus interface has not HBUSREQ and HGRANT, and HRESP when i trying to implement with AHB Bus. Is there any way to use AHB not AHB_lite. I can't use multi-layer ...
0
votes
0answers
28 views

RC Servos' potentiometer model/information [on hold]

I have a few disassembled RC Hobby Servos lying around, and started using their parts for different projects. I've become especially interested in the mechanical characteristics of their feedback ...
0
votes
1answer
42 views

Continuous-conversion vs Single-Conversion mode

I am working with an LSM9DS1 9DOF IMU and was wondering about some of the choices about operating the magnetometer. This is my first time working with an IMU, so I am having some trouble understanding ...
1
vote
1answer
35 views

How do charge controllers work?

I am creating a small wind turbine, I will be using a stepper as a low-efficiency generator. I have found off-the-shelf "wind charge controllers" but would rather roll my own because I would enjoy the ...
3
votes
2answers
63 views

Effective resistance seen by capacitor

I needed to find time constant of the above circuit. I guess we should first draw small signal analysis. The book found time constant as (RD+RL)*Cc. It says that we can find time constant using ...
2
votes
1answer
70 views

Using an array of resistors to give priority on a bus

I remember that the ZX Spectrum used an array of resistors to let the output from one chip override the output from another chip (on a bus) when both had the ¬oe pulled low. ...
-2
votes
3answers
207 views

What does this symbol refer to?

What is the symbol that is below the C1 capacitor and R1 resistor. Is it the symbol of grounding?
0
votes
1answer
59 views

INA155 reference pin not working

To test the INA 155 I gave a sine wave of amplitude 0.2 V p-p 100Hz. It was operated at 5 V single supply. The reference pin was connected to 2.5 V from an op amp buffer. There seems to be no offset ...
6
votes
2answers
888 views

Why are infrared LEDs used in optocouplers?

I read that optocouplers and optotriacs use infrared LEDs with infrared sensitive transistors. What is the idea behind using IR frequency but not visible light freq. LEDs inside a completely closed ...
0
votes
3answers
48 views

Measuring state of charge of a non rechargeable CR123A lithium battery

Is there a method (voltage, resistance, other...) of measuring leftover charge in a non rechargeable lithium battery? Background: I'm trying to get a general overview of power consumption for few ...
0
votes
0answers
16 views

Jfet switch common gate with dynamic load circuit [on hold]

I need to draw a circuit for jfet switch common gate design with dynamc load if there are used impulse generator! Can someone please show the design with dynamic load?
-1
votes
4answers
60 views

Motor control using potentiometer characteristics

I am trying to control a dc motor using potentiometer(armature control). Increase in voltage leads to increase in speed of motor. Even though this seems in accordance with general understanding, but i ...

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