texts:
I have been implementing a control software in C programming language. One of
the software modules represents a communication table for some proprietary
communication protocol. Each record in this table has one item (among others)
consisting of 8 bits. This item represents properties associated to this record.
Each record can has below given properties:

reported,
event_logged,
time_logged,
archived,
global

I need to define the communication table and for sake of readibility I don't
want to fill the properties of each record with values 0-31. My idea was to
at first define below given bit masks for individual bits in the properties
byte:

#define REPORTED       0x10
#define EVENT_LOGGED   0x08
#define TIME_LOGGED    0x04
#define ARCHIVED       0x02
#define GLOBAL         0x01

Then I wanted to define a macro with parameters which will prepare the content
of the properties based on human readable values

#define Create_properties(reported, event_logged, time_logged, archived, global){ \
  (uint8_t)reported | (uint8_t)event_logged | (uint8_t)time_logged |              \
  (uint8_t)global                                                                 \
}

The planned usage is following. For example one of the records in the communication
table will be event logged and time logged so I will write the macro in this manner

Create_properties(0, EVENT_LOGGED, TIME_LOGGED, 0, 0, 0)

and the expected result is 01100. I have been facing a problem that I am not
able to compile this source code. I always receive compiler error
"braces around scalar initializer". I have been using the gcc compiler. Does
anybody know why does this error occur? Thanks for any ideas.


texts: How to get max. throughput form SPI FLASH memory?

texts:
I have a number of arrays that are going to get stored on an external FLASH IC.

Important info about how the data is read:

The data from each array is read in ascending index order. So I might read index 0, 1, 10, 12... but never 0, 1, 12, 10.
The arrays are different in length.
After the array was read to it's end, it starts all over again.

During normal operation, about 353,600 bytes will be read per second from the FLASH to the MCU. With SPI Clk @ 4MHz this would take 88.4msec which leaves time for the MCU do to other things.

In fact there's a command byte + 3 address bytes on top of every transfer. This overhead makes the said transfer unrealistic.

Most of these SPI FLASH devices, such as the W25X40CLSVIG TR I'm about to use, have a hardware feature called hold. One can halt the transfer and resume it without having to re-send a commands & address.

If we'll assume there're 10 arrays, one could arrange the data on the FLASH like so:

array0[0] ,array1[0]..., array9[0], array0[1], array1[1]...

This would solve some of the issues because I'll have a much lower overhead, but after the 1st pass of the shortest array I'll be facing the same problem again.

Does anyone have a suggestion how to implement a solution that might make the transfer possible?


texts: Wiring colors for 'intermediate' connections

texts: It seems to that red is the color usually used to connect to the positive terminal and black is usually used to connect to the negative terminal. However, I have seen numerous other colors as 'intermediate' connections. What is a good coloring scheme to use when wiring various (basic) components into a breadboard. For example, here is an example of a circuit I've done below with red meaning direct connection to [+] and blue/black meaning direct connection to [-].


texts:
im new in here go easy on me,

I plan to securely erase an HDD with a microcontroller.

The ATA secure erase commands can be used to securely wipe HDD, is there a way that it can be reproduced by a microcontroller  to wipe a HDD
or
are there any microcontrollers which have SATA interface?

if so will there be bandwidth issue?


texts: Reading AC signal from a XBee analog input pin

texts:
I'm trying to use a ACS756SCA-100B - 100A Hall Effect-Based Linear Current Sensor IC (SCT-013-030) with a precision of 20 mV/A.

My objective is to read input voltage coming from the sensor into the XBee Analog input.

I was wondering if that would be possible by making precision half-wave rectifier, to rectify the sensor output into the XBee. I know that even with half-wave I still get a variation, so I guess that's far from perfect...

On the other hand I've seen these type of projects working with arduino, but as far as I understood, it will basically sample the AC wave a number of times and applies the RMS on it afterwards.

Is it possible to use XBee directly or must I process the wave first on a microcontroller?


texts:
I am reading Electronic Principles by P.E. Gray and C.L. Searle and I came across the following statement.

  If there are n capacitors
  and no capacitor loops, the highest power of s in the characteristic equation
  is n

Is there a proof of the following statement? and also what is meant in a capacitor loop?


texts:
What happens to electricity generated in solar panel when no load is connected?
How does it get dissipated?


texts:
I am trying to make a sensorless control system for a BLDC, using "Trapezoidal control", see here:
https://www.ti.com/lit/an/sprabz3/sprabz3.pdf?ts=1610192643720&ref_url=https%253A%252F%252Fwww.google.com%252F
The schematic looks like this,

PWM is applied on the top transistors during a commutation, while lower transistors are ON during the whole commutation.
Anyways, I need to measure the back-emf of the BLDC. In this document on page 2,
https://www.cypress.com/file/71631/download
one can read that the back-emf can be measured by measuring the non-energized phase. 3Ec = 2Vc. But when I measure this on the oscilloscope it doesn't really look like anything I can use.
I am measuring directly on one of the phases. During time period 1, the lower transistor is ON, and the voltage is zero. In time period 2, I suspect I see the back emf. In time period 3 the upper transistor is switching. And in time period 4 I think it is the back EMF again, but this time negative. Due to the mosfet diode the back emf is clamped to -0.7V during time period (I think).
has anyone here done anything like this? I need some guidance on how to properly measure the BEMF.

Edit: Another method is comparing with Vbus (mentioned in one comment below):

I measured now between Vbus/2 and one of the phases, and it looks like below. I set the "ground" of the oscilloscope probe to Vbus/2. The red circle marks where the phase equals half of Vbus. So that's what I need to trigger on in the MCU?
Edit2:
It seems starting the BLDC sensorless control is more complex than I thought. What I am doing now is simply switching between commutations to get speed. But I have read now somewhere that I need to accelerate the motor at a certain rate because "The angle between the stator and rotor magnetic fields must be in 90deg±30deg.". Otherwise I won't get a correct measurement of the BEMF. Page 25,
https://www.nxp.com/docs/en/application-note/AN1913.pdf
Is this really the case? Seems to make things substantially more difficult.


texts:
What are the required parts on a circuit to get a square wave out of a sine one following the constraint shown in the image?
Schmitt triggers seem to work on continuous sine wave but as you can see, I need to keep the variable volume information as is.
Do you know any part(s) that could do it?
Edit:
Oldfart corrected my graph. This is what I want to achieve. To me, the net result is the same but I understand how wrong I was with my waves looking into the future. My mistake.
I currently solve that situation in C++ but I was curious if HW could do it.


texts: How to mount an OLGA package IC for development

texts:
I need to mount an IC with an OLGA package in a protoboard or wirewrapping board for development. There is no development kit in the manufacturer's website for this IC, so all I have is two samples of the IC. The package is a really small 14 pin OLGA, defined in this diagram.

What options do I have to mount this little IC? Maybe there is a PIN socket for this kind of package? Or the only option would be to layout a custom PCB?


texts: How do you calculate the resistor value for a bicolor led

texts:
R4 and R5 have equal values. For both LEDs the forward voltage is 2V and the forward current is 30mA.

I know how to calculate the correct resistor for a single LED. However in this case I am using a voltage divider to create a 2.5V line so that the bi-color LED can show red or green when LOGIC is 0V or 5V. I am confused as to how to calculate the correct values for the two resisters.

I would appreciate a formula explaining how, and an explanation as to why it is that way.

Datasheet for the LED


texts: Is it possible for a voltage multiplier to be used to provide both positive and negative voltage?

texts: What I was wondering is it is possible to use a single voltage multiplier to provide a negative and positive voltage.  Referring to this voltage doubler circuit, if you connect a capacitor to the top right node, and an ac source to that capacitor, can it produce dc voltage with the reverse polarity? I think it looks like it would because the diodes would be in the opposite polarity relative to the capacitor.


texts:
I am performing a Load test on an LDO. I will be measuring:

Input current
Input voltage
Output current
Output voltage.

In the oscilloscope measurement settings I can see MAX, MIN, MEAN, RMS, PK-PK etc. Which one is the most appropriate one for measuring the above parameters, and why?


texts: Calculating Power and Setup using resistors as heating elements

texts:
I looked around at other questions, and either I didn't understand what all I was reading, or it didn't answer my question so if there is an article that I've missed feel free to redirect me.

I'm fairly new to electronics, and came in through Arduino so I'm pretty fuzzy when it comes to the actual electronics behind how things work.

I'm trying to create a heating device for heating a chest freezer that I'm trying to convert to a incubator. I have the "coding" side done with Arduino, now I'm trying to build the electronics. I have some relays that I'll be using to turn things on.

HERE IS MY QUESTION

I have a 12v 6a DC power supply that is powering my entire project. I'm trying to use 4 x 10W 12ΩJ Cement resistors. How should they be configured to produce my needed heat.

So I thought to myself, "I have 12v * 6a = 72w power supply, if I'm using 4 x 10w resistors 72 watts would be too much for them." I hooked them up this way though, the resistors in series, and they barely heat up, so I must not know how these things work even though I thought I did.

Is there a good way to calculate how much power a resistor should get for me to reach a specific temperature. Is there a calculator, or anything that can be used, or a formula, or is it resistor specific?

If I connect Just 1 or 2 in series they get ALLOT hotter, but then I'm worried about burning out the resistors.

Any help would be great, even if its a bunch of "Go look and read over here." comments.

Thanks all.

ADDITIONAL DETAILS as Requested

The space being heated is about 1.5 Cubic meters, I don't know the insulation type, its a freezer, and the other unit I'm looking to make this for is a wine cooler.

The reason for using 12v DC is incase of prolonged power outage that it can be easily run off of a battery back up, or a solar panel / battery system.

The space can be heated with a 40w light bulb fairly well. There are other commercial devices like this, that use a similar setup.

The temperature I'm hoping to achieve varies depending on the egg, but no more then 100F.

As far as the 72 WATTS I was just saying that is what my DC supply is putting out, It would be much more convenient to run it on less obviously.


texts:
The BJT Current equations are given as :-

IE = IC + IB

IC = \$\alpha\$ IE

IC = \$\beta\$ IB

Does the relations with \$\alpha\$ and  \$\beta\$ parameters include the reverse saturation  current ICBO  also ? Or should it be added separately ? Thanks.


texts: I read about distributed amplifiers. I know they are used in MMICs, but I wonder whether it would be possible to build a distributed amplifier with discrete components. In my opinion, it would have the advantage that the output power of the amplifier is distributed to the individual transistors. Would it be possible to construct a distributed amplifier with discrete transistors, say, for 2 GHz?


texts: I am using a twin lead folded dipole antenna for an FM receiver. I have a few questions regarding impedance matching. I know impedance matching is needed to have maximum transfer of power between stages, such as from the antenna to a band pass filter stage before the signal is feed to a RF stage. I know that the antenna has an impedance of 300 Ohms, so if I connect it a coaxial cable of 50 Ohms via n:1 balun transformer which will be connected to my pcb by a connector, do I still need to worry about impedance matching from the output of the coaxial cable connector to the input of my band pass filter? If so, do I place a 50 ohm resistor(50ohm from inductor or capacitor) before the input of the next stage to match, Or can I just connect the signal to the input of the next stage an no additional impedance network ? Also is it possible to just take the feed line of the antenna (300 Ohm) and match it with an impedance network to connect to the input of the next stage on a pbc, or would this be unwise and ineffective?


texts: How can I limit current on a 24VDC motor at start up?

texts: I am trying to lift a platform hydraulically with a mini power unit that has a 24VDC motor.  We are using a converter box to convert 110VAC to the DC of the motor.  These converters are only rayed to 40 amps.   We have a roughly 200 amp, 24VDC inrush current that lasts between 0.5-1 second and it is too much for the motor at start up.   I am desperately looking for a solution.  I have looked at capacitors with no success.  Someone suggested  “soft start”/voltage regulators, integrated load switches, or thermistors.  I have no knowledge or experience with any of these.  I am not an engineer.  I'm searching for solutions for my friend.  Any help or suggestions would be greatly appreciated. GXC


texts: I saw this as a package type for an attiny microcontroller in the digikey catalog. I'm pretty sure that "QFN" stands for Quad Flat No leads. However, I'm not sure what prefixed "WF" means. Is there a standard reference that would have this information?


texts:
I am currently using pin 13 and the ground pin to connect an old salvaged buzzer from an old stationary phone. Also I am using this command to power it's tone(13, 59, 30000).

Does this have the potential to damage the pins or the microcontroller itself? I aim for the loudest sound possible. Is there any other way to do this maybe through different pins (5V, Vin, etc) in order to avoid using a resistor?
Or HAVE I to use a resistor to not damage the Arduino no matter what?
Maybe I could use a transistor setup to control the buzzer? Or is the Arduino safe anyway and I should just carry on doing what I am doing (pin 13 and ground)?


texts: DC-DC Converter - Why is the input voltage called Vg?

texts: In the textbook I'm reading (Fundamentals of Power Electronics 2nd Ed, Erickson and Maksimovic), the input voltage for several different types of converter circuits is labeled Vg. The textbook gives no explanation for what the g refers to. Does anyone know?


texts: Can I identify an LED's characteristics from the transistor used as its current limiter?

texts: I'm a total NOOB, but I am teaching myself electronics while in retirement. I want to change the color of the "Power ON" LED in my mod of an ATX-PSU, but I don't know the characteristics of the LED. Current to the LED is controlled by a Fairchild C1815 NPN transistor. Can I use the C1815 data sheet to ferret out the LED's numbers?


texts: What features of C++ lead to extra resource usage that I should be aware of when developing for an embedded system?

texts: Some features of C++ have implied run-time cost or can lead to significant code size increases.  Which features should I consider avoiding when developing for a bare-metal resource constrained microcontroller? And why?


texts: What is the function of series inductors on the motor phases of a commercial brushless EC/BLDC motor controller?

texts: While designing my own BLDC controller I got curious about how the big boys do it and opened up a commercially available one (Maxpos 50/5). Most things were quite straightforward, except a 11.3uH series inductor in series between the the current measuring resistor of each half bridge and the motor phases connector. I have never seen anything like this ever before, and am very curious as to what the function of it might be. Any ideas?


texts:
We are going to use GAP PAD HC 5.0 thermal pad to transfer the heat from a FPGA (XCKU040) to a heatsink. My question is regarding the thickness I should choose to obtain best performance.

On the one side, I understand that lower thickness = lower thermal resistance = higher heat transfer. On the other side, higher thickness allows it to absorb more deformations in the chip / heatsink surface, but it is worse in terms of heat transfer.

Is this correct? Any more ideas?

Thank you very much.


texts:
My question is very specific but I might face difficulty framing it well so hope I dont get penalized.

Background: Playstation 1, houses 32-bit RISC MIPS R3051 processor, running at 33.8688 MHz with 2 MB RAM, 1MB video RAM. The games targetted for this platform runs smoothly. On the other hand an Ingenic 32-bit XBurst MIPS processor runs at 600MHz, with 128MB RAM, and can support the games for Playstation 1 in emulation.

Concern: Now both are MIPS processors, one running at 34MHz and other at 600Mhz, The Ingenic cpu with its specs is an overkill for PS1, however the performance of games running under Ingenic cpu, running embedded linux, is quite poor in various cases.

Question: My question is, in such cases, does the performance depends on the fact that one is running an operating system with operating system overhead and the other running proprietary firmware? Or the fact that the emulation software has to perform dynamic runtime compiling which utilizes too much CPU time and hence result in poor performance?


texts: Why longer stubs cause more intense ringing?

texts:
Why connection of longer stub lengths cause more intense ringing in a Communication Network like CAN?

As stub lengths increase won't the attenuation increase and lead to less ringing? Also the time taken for the multiple reflections will increase so won't the ringing be less?

Please explain in terms of reflections.

One more doubt regarding multiple reflections I have is that if there is no attenuation will these multiple reflection cause continuous increase in amplitude of ringing?


texts: how must I connect a USB micro b connector to reach 5v?

texts: I'm designing a circuit and want to power it through a USB Micro B connector. I have already installed the connector on my board, but after connecting the USB female connector of the wire to my computer, I don´t get any voltage on the Micro USB B connector. How must I connect it? I used to use a USB B connector on my through hole prototype and it worked very good but it had only 4 pins. Can anyone help me?


texts: Meaning of dB while dealing with amplifier(Op-Amp)

texts:
I have found a question in MIT open-course material.The question is to

  Design an amplifier(Op-Amp) with a gain of 20dB

While searching about db in the Internet I have found out that 20db is defined as follows:(in this case they are dealing with sound wave)
20dB = 10log(100I0/I0)

But The MIT open-course material has  provided answer .While dealing with dBit approaches as follows:
From the definition of dB we have: 20dB = 20log(Vout/Vin)

But, from my above searching it should be
20dB = 10log(Vout/Vin)

Moreover the questioner of this question says that db in amplifier is meant to be 10*log(Pout/Pin). What is the thing I am missing here?(which factor? 10 OR 20?)

Link to MIT material is Here (Page-20)


texts: What's wrong with my input circuit? LTspice

texts:
I am designing my first power electronics board in LTspice to convert single phase AC to DC. This DC is fed to asymmetric bridge to drive an SR motor which is connected to a flywheel. This flywheel stores energy and supplies stored energy to the grid when required. The H-bridge inverter uses freewheeling diodes as a bridge rectifier to convert input AC to DC (Motoring operation). Where as the inverter chop up the DC voltage from DC link into an unfiltered AC voltage(Motor acting as generator). This chopped AC voltage is then passed through an output filter in order to smooth out the current waveform passing into the grid. This is the idea of the project.

But in beginning itself the input from the AC mains is not giving a sin wave but giving a rectified AC. Am I missing something in my circuit?

I would be very grateful if somebody could help me.

Thank you.

Note: Eventhough the gate voltages are in a controlled by a DSP, inputs of gates are fed with voltage sources for simulation purposes.


texts: Why an antenna is used in this electronic electroscope circuit?

texts:
Why is an antenna is used in this electronic electroscope circuit?
I would like to do this as my mini project.


texts: Anti-aliasing filter with a higher corner-frequency (>10 MHz)

texts:
I'm currently working on a design with an adc3424 ADC with 125 MHz sampling frequency. This is my first design with an ADC and I assumed picking an anti-aliasing filter (AAF) would be a trivial task. Linearity or passband ripple is not a critical factor. How come it seems to be a rare thing with AAFs with corner frequencies above 10^5 Hz? Something like 60 MHz would make sense here.

On digikey, there are not many active AAFs. Other filters with higher corner frequencies do not seem to be for anti-aliasing. Could anyone direct me to where I can find what I'm looking for? Thanks!


texts:
The circuit below is the beat frequency oscillator in a superhet receiver. Q1 is a Colpitts oscillator whose output is buffered by Q2. C3 is a trimmer to fine-tune the frequency.

simulate this circuit – Schematic created using CircuitLab
The circuit oscillates at the expected frequency of about 20MHz, but the output amplitude is very unstable and jumps around randomly by at least an order of magnitude, seemingly without provocation. It's also too low: I'm getting about 3-30 mV(rms), and I'd need about 300 mV at least. How can I predict the output amplitude of this oscillator, and what can I do to obtain a more stable and higher amplitude?
Another thing I've noticed is that the oscillator around Q1 produces a relatively pure sine wave if I cut it off at R2, but as soon as I add the amplifier stage, it gets significantly distorted. Can I do something to fix that? And Q2 runs quite hot.
This question is related, but I'm not sure the advice given there applies in this situation:
How to increase the amplitude of a colpitts oscillator circuit?
EDIT
Some experiments based on KD9PDP's suggestions. I got a bit more consistent amplitudes of about 200mV today, so there could be a problem with some of the earlier measurements. It's possible I didn't always have the correct load on the output (if it wasn't just the weather). Nevertheless, I still need to increase the amplitude by at least 50%.
Increasing C1 has little effect on the output up to at least 570 pF (100+470 parallel). The amplitude changes by no more than about 10%. After adding 2.2 nF in parallel to C1, the oscillation doesn't start.
After increasing R6 to 1k, Q2 goes into cutoff and distorts the negative half wave. However, I can get away with raising R6 to 390\$\Omega\$ before distortion sets in, and then Q2 stays noticeably cooler.
Eliminating R2 also causes cutoff and distortion for all values of R6 I tested.


texts: percision timing ratio of multiple lights blinking with different durations and intervals

texts:
I'm learning a lot of this as I go, my background is mostly in programming.  I'm trying to setup a timing circuit for two sets of lights going into a model, and am trying to determine the best way to go about it. The setup is this: The first light set starts on, then goes off at 0.5s then stays off for 1s.  The second set of lights come on for 0.025s in the middle of the on and off periods of the first lights so on at 0.25 sec for 0.025s and then again at 1s.

I've done some rough prototyping using a 555 oscillator, a digital counter, and logic gates to hard code the timing for the shorter strobe lights. I know I can hard-code a sequential logic for the longer lights, but that seems as it would take up a bit of real estate using just straight logic gates.

I've considered possibly using a programmable logic array or FPGA to handle the logic for the counter output, but don't know enough about either to know which would work best.

Ideally I want to avoid using an Arduino unless I can put a small processor on the board instead. I need to keep the design as compact as I can since it will be installed inside some very tight spaces inside a model.

The overall timing period of the lights can change a little, the key is the ratio between the two.

I've looked around and found questions here about 1 set of lights with verying timing, but not a situation like I have here. Any help or suggestions is much appreciated.


texts:
I'm learning to control a servo (SG90). I read at this tutorial: http://www.seattlerobotics.org/guide/servos.html

  The servo expects to see a pulse every 20 milliseconds (.02 seconds).
  The length of the pulse will determine how far the motor turns. A 1.5
  millisecond pulse, for example, will make the motor turn to the 90
  degree position (often called the neutral position). If the pulse is
  shorter than 1.5 ms, then the motor will turn the shaft to closer to 0
  degrees. If the pulse is longer than 1.5ms, the shaft turns closer to
  180 degrees.

Is this true for SG90 ?  I can't find this info at Specification :

Operating Voltage : 4.8~6.0V
Operating Speed : 0.12sec/60 degree(4.8V)~0.1sec/60 degree(6.0V)
 Torque :  1.6kg/cm(4.8V)
 Dead Band Width : 5usec
 Temperature Range : -30~+60?
 Cable Length : 25cm
 Servo Type : Analog Servo
 Brand Model :                 SG90


texts: Why is the duty cycle much wider than it should be? PIC32MZ & PWM

texts:
I'm working with the PIC32MZ2048EFM100 and XC32.
I'm using some outputs as PWM signal generators.
There are frequencies for which the pwm works fine, but not for others.
For example to get 24.4 kHz, I make the following configurations:
PR2 = 255 (I use timer 2)
TCKPS<2:0> = 011 = 1:8 prescale value
TPB = 1/50 MHz
Duty Cycle = OC1RS = 0x05.
If the period is given by PR2 plus 1, which would be 256, the duty cycle is very small, but when analyzing this signal with an oscilloscope, the duty cycle is very long, greater than 50% of the signal period.
Any suggestion of what's up?
I attach an image of the signal displayed on the oscilloscope and a capture of the registers T2CON, OC1RS , PR2 & OC1CON.


texts: Properties of an Ideal Transformer and the reasons behind them

texts: Why should the  magnetising reactance of an ideal transformer be very large i.e. approach infinity? What practicality does  this imply?


texts: Adjustable constant current source using a lm317

texts:
I am looking to provide constant current source, I am using a LM317 right now and it seems to be doing the job just fine. however I need to switch it between 2 or 3 different current levels. I can not seem to find any information on this or figure it out(I cant help but think I am missing something simple)

It needs to be switchable with a 3v3 micro controller, and the voltage coming out of the current source may need to be higher then 3v3(up to 5V depending on current selected).

Can anyone help me out or point me in the right direction.


texts:
I was trying to create a low voltage (30V) rail-gun. I have quite a hard source of power that doesn't drop voltage upon current drain, further more, this source is re-inforced by big Tesla capacitors.

Unfortunatelly, I've achieved nothing using my setup. I used materials at hand for the purpose.

The rails are pieces of a construction set for kid-engineers. They are made of iron. The projectile was a very thick piece of copper wire.

Obvious failure is, that the inital spark solders the set together. But even after further attempts to move it (poking it with my finger) it doesn't appear to be forced in either direction.

Is my rail-gun shape good? And is my low-power capable of moving anything this way?


texts: Solving a block diagram problem of an LTI-System

texts:
I have been trying to solve this particular question for about 2 hours, but I am missing something.

I am supposed to calculate the total transfer function of this network, with the total transfer function defined as Y/X .

The two nodes at the top right confuse me, as in, I couldn't figure out which signal is being transferred to the adder in the middle. I got halfway there before I made a mistake, because my solution indicated either an endless loop or the transfer function wasn't linear.

What am I missing here? Thanks!


texts: How to understand the EIRP criteria in 47 CFR § 15.519 for UWB device?

texts:
I have difficulties to understand the EIRP critera in 47 CFR § 15.519 for UWB device.It says,

(c)...a device...shall not exceed the following average limits when measured using a resolution bandwidth of 1 MHz:

+------------------+-------------+
| Frequency in MHz | EIRP in dBm |
+------------------+-------------+
| 960 -   1610     | −75.3       |
| 1610 -  1990     | −63.3       |
| 1990 -  3100     | −61.3       |
| 3100 - 10600     | −41.3       |
| Above 10600      | −61.3       |
+------------------+-------------+

and

(d)...shall not exceed the following average limits when measured using a resolution bandwidth of no less than 1 kHz:

+------------------+-------------+
| Frequency in MHz | EIRP in dBm |
+------------------+-------------+
| 1164-1240        | −85.3       |
| 1559-1610        | −85.3       |
+------------------+-------------+

and
(e) There is a limit on the peak level of the emissions contained within a 50 MHz bandwidth centered on the frequency at which the highest radiated emission occurs, fM. That limit is 0 dBm EIRP.

for this (e), as further explained in § 15.521 part (g) that if a resolution bandwidth is not 50MHz,
one can use 20*log*(RBW/50) dBm, where RBW is the real resolution bandwidth in use.

My understanding is:

(1)for example for 960-1610MHz, <-75.3 dBm with resolution bandwidth of 1MHz means
the power density is -75.3 dBm/MHz, which means
in every 1MHz section of this frequency range, the total transmitted power of the device in this 1MHz range should be less then -75.3 dBm.

(2) But I don't undersand why with 1KHz resolution bandwidth, in 1164~1240MHz, EIRP in dBm is -83.5. I would guess -75.3dBm-30dBm=-105.3dBm because 1KHz is just 1/1000 of 1MHz, and the total power in this bandwidth would be 30dB less.

(3) I don't understand § 15.521(g), why use 20*log*(RBW/50) dBm, rather than 10*log(RBW/50)

Would you please help me to understand this?
Thanks!


texts: Should wires be tinned to under the insulation?

texts: When tinning a wire with solder, is it better to allow the solder to go under the insulation (so long as it doesn't bulge or burn the insulation)? I've heard arguments for both, but never really got a final answer.


texts: Should I connect RXD to TXD and vice versa?

texts:
The circuit below is used to flash firmware to a microcontroller. There is a Micro-USB port on the PCB used to connect to a host computer. The USB lines (D+, D-, etc.) then go through a bridge chip (datasheet) and form a UART connection with the microcontroller. Should I take the RXD output of the logic bridge and connect it to my microcontroller's TXD or what?
This application doesn't require flow control (correct me if I am wrong), but if it did, would I cross the RTS and CTS lines?


texts: Sending data through the iphone headphone jack

texts:
I recently bought a TRRS Pigtail on sparkfun and I want to have two buttons attached to one end of the cord and another end connected to the iphone in the headphone jack. I would like to be able to have an app detect when a button is pressed.

How would I be able to do that?


texts: I have a voltage of 9v output from a solar panel and another 2v from a stepper motor wind mill, if I connect the two together will the output then be 11v?


texts: Can polarity be reversed to effectively reverse the output of its intended/motored function?

texts:
For "simple" electric items/tools with motors -- ones without complex electronics -- can the polarity be reversed to effectively reverse the output of its motor? In particular, I'm wondering about an electric duster:

http://www.amazon.com/Metro-Vacuum-ED500-500-Watt-Electric/dp/B001J4ZOAW/

It's a high-powered blower duster, however, I've wondered about the possibility of reversing its polarity to essentially have it double as a handheld "vacuum".

In general, could this be done, and if so, is it a simple matter of reversing the polarity or would it not be a simple "backwards==forwards" matter?


texts: What is problem with NRZ and how manchester line coding handles out of sync tx and rx clocks.?

texts:
I am reading about physical layer of the OSI model. Specifically the different ways in which digital bits can be represented as voltage levels, among the multiple types are:

NRZ.
Manchester encoding.

My understanding of NRZ encoding, when both tx and rx clock are synchronized, is as follows:

It is stated that tx and rx clocks might go out of sync in which case NRZ encoding will have issues when decoding long strings of 0's (or) 1's, and manchester encoding addresses this problem.

I am having hard time understanding the logic. A picture is worth a thousand words, so can you please help me understand this with a clock /signal diagram that shows.

tx clock.
rx clock (drifted)
tx data (nrz)
rx data (nrz)->how drifted clock has affected data.
tx data (manchester)
rx data (manchester) -> how manchester handles rx clock going out of sync.


texts: How do I proceed when the current is Io = 2cos (wt)?

texts:
I have this problem:

And I would like some help with how to proceed.

My own thinking:

I think Io = 2cos (wt) mA should be 2 mA. For VR (t) I think it should be VR (t) = 2 mA * 1000 = 2 V and for the capacitor I think I should use 1 / jwC = -j 1 / wC = -j 1/10 ^ 5 * 10 * 10 ^ -9 = -j10 ^ 3 ohm = -j kohm and to get Vc (t) it becomes Vc (t) = 2 mA * -j kohm = -2j V.

Am I thinking right or am I on the wrong path?


texts:
I posted a question about a week ago about impedance and have a follow up if you will indulge me.
I'm comparing input and output impedance from TTL and CMOS ICs, specifically 7401 and 4011 NAND gate ICs.
I know that the frequency plays a part but generally I am led to believe that Vcc-Voh/Ioh gives me the high logic output impedance and Vcc-Vol/Iol gives me the low logic output impedance. Right?
For the 4011, the datasheet gives a min Voh of 4.95 at Vcc 5V. So 5-4.95/Ioh(0.88) = 0.05/0.00088 = 56 ohms. Sounds about right. Right?
For the low logic, Vol is max 0.05V @ Vcc 5V. so 5-0.05/Iol(0.88) = 4.95/0.00088 = 5625 ohms. From my internet research, the output impedance from CMOS ICs is low in either logic state so the value of 5625 can't be right. Right?
Also taking the input impedance I'm using Vcc-Vih/Iin and Vcc-Vil/Iin which gives me a high logic impedance of 13Mohm and 36Mohm @Vcc15V (15V as that's all that's provided for Iin) Is this about right? I can't help but think that I should be doing something with Vo as it's specified in the conditions for Vih and Vil.
Datasheet attached

If you've read this far perhaps you'll do me another solid. Why does the output impedance matter? I understand that the high input impedance is important for driving other logic gates but what about the low output impedance?
Thank you so much. Appreciate the help I receive here


texts: Regarding transistor RC Phase Shift Oscillator

texts:
I have been recently studying about the transistor RC phase shift Oscillator. I calculated the attenuation provided by the RC network to be equal to 29. But when we use a transistor to make the circuit the attenuation will not be equal to 29 because the input impedance of transistor is not very high. Correct me if i am wrong. I have been following this website. It mentions that the the gain of the transistor to be around 56 which is way off from 29 but it doesn't tell how to derive the formula. I have searched various but i couldn't find any source which explains it in detail.

Since i am very new to electronics this is very confusing to me. Can you please tell me how to derive the formula.


texts:
Currently I have a 60W amplifier for the 400-500MHZ band with a 50Ω impedance. In order to prevent jamming other frequencies I will need a low pass filter to block any frequencies above 500MHZ. I just made a full Internet search and haven't found any low pass filter capable of supporting 60W preferably 100W.

Since I'm new to electronics and have no experience in building Low Pass Filters or have an oscilloscope to fine tune. For the 60W amplifier I was thinking in buying separately 12 identically low pass filters  (8 watts max each) and then put them in parallel so that each one shares only a load of 6W and all the system a total load of 60W and a theroretical max load of 96W (8w*12units). In case I would need more power it would be just a question of adding more low pass filters in parallel. Feasible?


texts: What are the Benefits of a Two Dimensional Silicon-Based Transistor?

texts: It is in the news that now a group of researchers were able to create a two dimensional silicon-based transistor. A question come to mind that, what are the benefits of a two dimensional silicon-based transistor?


texts: computing shunt resistence for a microammeter

texts:
Let's suppose I have a dc microammeter with a range of 100 ua that claim to have an internal resistence of 1Kohm.
I want to use this instrument to measure a range of 1A. I'm assuming I need a shunt resistence producing a voltage drop makinga 100 ua current flowing in the instrument:

i*Ri=I*Rshunt

where i is the instrument range, Ri the internal resistence RShunt the unknown shunt resistence and I is the desired range. For a range of 1A this yield a resistence of 0.1ohm, am I wrong ?


texts: RGB Controller, switching frequency interferes with IR receiver

texts:
I am trying to build a color fading RGB controller with an ATmega328, three MOSFETs and an TSOP4838 IR receiver. The RGB LED is 50 Watts and is driven by a 45 Volts off the shelf switching power supply.

The IR decoding I have programmed works perfectly if the RGB LED is not lit. It also works if the LED is running with 100% PWM duty cycle. But as soon as I change color to some RGB mixture where duty cycle is not 100% (at around 350 Hz or so), the IR receiver seems to provide junk signals and so the IR remote doesn't do anything. The MCU still works because the color is still shown correctly. Also, the coupling doesn't seem to by optical (I guess a tiny little bit of visible red might go through the IR filter of the receiver, especially at high brightness) because shading the LED doesn't improve anything.

But the oscilloscope shows that the 5V operating voltage for the MCU and IR receiver is oscillating with the PWM frequency in the range of several tens of millivolts. And on top of that there are very sharp spikes, several tens of nanoseconds in length, in the several hundred millivolts range that seem to come from the switching power supply for the LED (but the spikes don't seem to be the problem because they are also there at 100% duty cycle). Overall I guess it could be called a truly messy nightmare of an EMI scenario.

But my electronics knowledge as opposed to my programming knowledge is not good enough for me to know what to do against these problems. I have tried several things, to no avail. For example, I have put an active filter (R, C and Transistor in common collector circuit) before the converter that provides the 5V. Also putting big electrolytics to the 40V and the 5V did not help. In fact I am not really sure if I have understood the coupling path(s) that cause the problem. Is it via the power traces directly, or is it coupling via the MOSFET gates back into the MCU and from there disturbing its digital inputs or the IR receiver? I guess the PWM frequency (300 something Hz) is too low for parasitic impedances to become important. But other than that, no idea.

What could I do?

PS: in the meantime, I have increased the value of the bypass capacitor on the TSOP from the recommended 4.7 uF to up to 220 uF in order to stabilize the supply voltage of the IR receiver. The cap and the resistor of this RC-filter have been soldered directly to the IR-receiver. But still no success. Using a battery improved things a little bit, but there were still operating states where there was interference from the PWM frequency. I am out of luck...


texts: What happens if I connect a transformer in reverse?

texts:
I was thinking the other day. A transformer is just two coils, right? There is no polarisation or anything else fancy? The ratio of the number of windings on the input to the number of windings to the output reflects how many volts are outputted given the input?

So if I connect my 250V to 7.5V transformer to the mains in reverse, will I simply get 8.33KV? I assume so.

More practically, what will happen? From memory, the breakdown voltage of air is approx 1KV/cm. Doesn't this mean there would be all sorts of streamers between the transformer output terminals? What about between the windings themselves? Surely the thin layer of insulation around the transformer windings tightly wrapped doesn't insulate that much?

And say there are streamers between the 8KV outputs of the transformer. What then? Fire? Blown fuse?


texts: 66 GPS channels for 22 satellites - why the factor of 3?

texts:
Modern GPS chips can use signals from many satellites at the same time to obtain a solution. While typically 4 are necessary, a larger number helps improve the solution with some types of errors.

As an example for this question, the Adafruit Ultimate GPS uses a GlobalTop FGPMMOPA6H chip. The Module is said to have 66 channels and be able to track 22 satellites simultaneously.

My basic understanding of (at least the coarse acquisition stage) of GPS signal processing is that the antenna signal is amplified, possibly shifted in frequency and demodulated. All satellites broadcast in the same frequency band, but the signal from each is modulated by a unique Gold code. The signals are identified by correlation - the chip decides which satellites might possibly be above the horizon and loads those Gold codes into the correlators.

There are about 32 GPS satellites, so 22 is more than enough from the surface of the earth (space is a different matter).

But why are there 66 channels for 22 possible satellites?

Reading this answer "You need one channel, per frequency, per satellite." it looks like the factor of three (66/22) might come from the ability to track L1, L2 and L5 signals, but I am not sure that's what is happening here. However this answer The number of channels inside a Navigation receiver is definitely more than a marketing gag suggests that L5 requires two correlators by itself.

Why 66/22?


texts: How to measure resistance across a capacitive load using an Agilent 34410A in GPIB mode

texts: I'm trying to measure resistance across two test points in a circuit that has an overall capacitive load. This is for a very specific application and it is to ensure there are no shorts in the circuit. When I use my Agilent 34410A manually (continuous triggering) I have to wait for a few seconds for the capacitors to charge up and then I get a high resistance value as expected, showing there are no shorts. But I need to do the same thing using GPIB. The trouble is, when I use the GPIB commands such as "MEAS:RES?" or "CONF:RES; READ?" or "CONF:RES; INIT?; FETCH?", they all take a quick snapshot of the resistance and don't provide the capacitors enough time to charge and so they show a very low resistance reading. Is there a way I can mimic the continuous trigger reading that I can do manually, but using the GPIB mode?


texts: How can I convert an audio signal from a phone to 0-5v for a microcontroller?

texts: I am trying to build a micro controller system where I input music from a phone/tablet and control the volume using a hardware keypad and do other stuff with the audio. I am trying to understand how to convert the +/- 2.5 V audio signal from phone to 0-5V for micro controller input. Thanks


texts: ADC0808 IC working correctly occasionally

texts:
I am using ADC0808CCN for a project on converting analog signal to digital signal. It has an inbuilt multiplexer using which we have to provide an analog signal to one of the pin. However what happens is ;

Sometimes it latches to a particular value say 1000000 and remains at there no matter how many times Start of Conversion is pressed which should set the inner counter to 0.

Sometimes it gives slightly wrong output off by 100 or 1000 and when I press Start of conversion, it gives correct output, so its not reliable every time.

And most seriously , Suppose the control for multiplexer according to Datasheet are such that input pin 1 should be active, instead, it works only when the input is given to pin 5 for one particular IC and pin 3 for other.
I have been trying to fit it in logic since 3 days however each day some new error happens. I have replaced it twice from my college lab and now the technician doesn't want to replace it anymore . What is amiss here ?


texts: Does the base-emitter connected BJT have the same built in voltage as the base collector connected BJT? Why or why not?


texts: A basic question about inductor current in a switching circuit

texts:
Regarding the circuit below, when the switch is opened very fast according to the formula V(t) = L (di/dt) how can we interpret why the inductor current changes direction?:

During the switch is closed, the current flows in steady state from the upper terminal of the inductor to the lower terminal of the inductor. But the moment the switch is opened the current "wants" to flow the opposite direction. By "wants" I mean something causes it to flow that way. How can we relate this and the formula V(t) = L (di/dt) to explain what is happening more clearly?

Edit:

Does the inductor polarity really reverses here:?

Edit 2:

This is regarding an answer:


texts: I bought a relay and until home hasn't noticed that its limited to 1A 125VAC. Then I found this datasheet which says that it can be used for 250V. I live in Europe so I thought that maybe that relay was produced for American market and despite that indication on its casing, it can be used with 250V. Is this possible?


texts: I am working on a project and I need to measure the light from a light source as a human would perceive it. I was considering using a luxmeter (https://www.amazon.com/Leaton-Digital-Luxmeter-Illuminance-Display/dp/B018QLIVSC/ref=sr_1_5?ie=UTF8&qid=1486326183&sr=8-5&keywords=lux+meter). Will a luxmeter give me accurate readings? Will it work for a light that is dimmed with PWM (will it return the average value, or will it fluctuate)? Thank you!


texts: 11GHz,100 watts microstrip power divider

texts: is it possible to build 100 watts, microstrip power divider work in 11GHz?


texts: Why OLED/AMOLED screen technology create ilussion colour?

texts:
OLED and AMOLED screen unit is pixel that made by three main LED colour. They are RED, GREEN, and BLUE.
For other color, like YELLOW it combined from RED and GREEN. But, is it really combined? I mean it combined by special glass that each emitting light through it then combine them and create new light (yellow) .
Or, every LED directly emitted to our eyes without through that special glass?
If it directly, then how can our eyes detect it as yellow while in nano scale we see it as RED and GREEN are turning ON?


texts:
I have two P89V51RD2 microcontrollers, Out of this only one is working fine and in the other one the bootloader is corrupted. How can i replace the corrupted bootloader using working P89V51RD2.

Can i use MOSI, MISO & SCK pins of P89V51RD2 microcontroller ?


texts:
I have the following problem:

MY ATTEMPT

Okay on this site, https://www.jcalc.net/motor-current-calculator, I found a formula for the motor current with full load and a 3-phase supply:

\$I=\frac{P\cdot 1000}{\sqrt{3}\cdot V\cdot pf \cdot \eta} \$, where \$ P\$ is the motor power rating, \$ V\$ is voltage, \$pf \$ is the power factor, \$\eta \$ is the efficiency. Plugging my values into the equation we get:

\$I=\frac{P\cdot 1000}{\sqrt{3}\cdot V\cdot pf \cdot \eta} =\frac{12\text{kW} \cdot  1000}{\sqrt{3} \cdot 220 \text{V} \cdot 0.89 \cdot 0.87}=40.67 \text{A}\$

This seems like a VERY large current and it made me doubt my answer.

Have I used the correct formula, and used the information correctly - at the moment I don't use the fact that there is a slip of \$5 \% \$. I hope someone can help me with this.


texts: I have a microcontroller and an FPGA on the same board.  If they're both going to run at the same clock speed, can I just use one oscillator to clock them both?  There seems like there is something I should watch out for here, but I can't immediately think of any problems with it if I just keep the traces short.  Has anyone done this before?  What would be some common pitfalls of doing this?


texts:
I know the add instruction in mips32 will do overflow detection, i.e. add $t0, $s0, $s1; I want to know whether this feature will make it slower than addu $t0, $s0, $s1, which won't detection overflow.

Clarification:

For make anything faster: I assume that overflow detection in done by hardware. Then I want to know the hardware components itself for add, addu which is faster.
For Which implementation: The book I read mention about R2000, but think the solution is an general hardware design principle, which should not be restricted to a specific version. (i.e. I think there should be some requirement that clearly state whether it should cause delay.)


texts: Mass liftable by a \$15 \,kg\cdot cm\$ torque stepper motor

texts: I'm working on a project for automated welding and I'm using a stepper motor. I am confused in relation to its rated \$15\, kg \cdot cm\$ torque. Can you explain what does it signify?


texts: What is the purpose of these diodes in half bridge

texts:
I am checking out a schematic for a full bridge and I noticed these diodes at the gate of every mosfet and I do not understand their purpose there. Can someone elaborate please.

The IC to the left is a half bridge driver... the output to the motor is at the far  right.


texts: Make-Before-Break Relay with Very High Continuous DC Current

texts:
I need to use a relay in order to do field sweeps with my electromagnet, which is hooked up to a couple very beefy monopolor power supply. (My magnet's impedance is  ~2 Ohm, and I am putting ~40 Amps through it at maximum power).

Initially, I figured the Potter & Brumfield T92 Series Two-pole 30A PCB Relay would work for me.

A cursory glance at the contact data revealed:

Rated Current: 30A
Limited Continuous Current: 40A
Limited Making Current: 40A
Limited Breaking Current: 40A

I assumed I would be pushing the limits, but this relay is $13 and I had one laying around.  However, then I looked at the contact ratings, and I saw, under the 'Load' header:

40A, 277VAC, resistive
30A, 120/277VAC, resistive
10A, 600VAC, general purpose
20A, 28VDC, resistive

Where I have italicised the rating that concerns me. Is this to say that I should not use this relay? Does anyone have any idea what kind of relay I should use? When I look at "power relays," they all seem to have just two contacts, rather than the eight that I would expect... Also, how do I tell if the relays are make-before-break or break-before-make? I know that the one I have now will work, only because I know someone else who is using it for the same thing...

Thank you for your help!


texts:
I was watching one of Razavi's online videos

https://youtu.be/gjKTAx9FQHo?list=PLO4mxQzfcml_56XSGcA8ULOv7qEtZd0Hy&t=2627

At time 43:45

He considers two scenarios (part of the same differential movement):

The gate of M1 increases. Thus, the current in the left branch increases, hence due to the current mirror, the current in the right branch increases. Thus, if we remember the Id-Vds curve of an NMOS, if current increases, Vds increaes, our drain of M2 is the output voltage. Thus, the output voltage increases. This makes sense to me too.
The gate of M2 decreaeses. Thus, the current in the right branch must decrease. Razavi says that due to this, the output voltage will increase as well. I don't understand why? If M2 current decreases, then surely from the Id-Vds plot, Vds should fall and hence the output voltage on the drain should decrease too? Why is he saying it will increase?


texts: What is the best design practice to view multiple clocks that are generated from a single PLL within an FPGA?

texts: Assume we have two clocks of 100 mhz and 200 mhz both generated from a PLL within an FPGA. If they are seen as two independent clock domains, then everything should work fine in the design, but there will be added complexity due to async fifo's or other metastability prevention techniques. If they are seen as belonging to a single clock domain, then l guess  we will have to do deskewing by adusting the phase offset within the PLL which according to my experience will be troublesome due to the required post-route simulation, and which is near to impossible for big designs ( unless you are willing to wait for the long simulation time). So I'm just curious as what is the best design practice in such a case. Also if the obtained clocks are not a multiple of 2^n, say 50 mhz and 150 mhz, then what solutions are used in practice. I appreciate your kind answers.


texts: Is the calculation of weight to be suspended inorder to produce electricity from an alternator correct or not?

texts:
I bought a alternator with the following specs:
power: 5 hp
rpm: 1800
voltage: 220V
The formula for finding the horsepower is:
horsepower= (RPM X Torque)/5252
By substituting the value of horsepower and RPM (as provided) in the above formula i got
Torque= 14.5 N-m
suppose that a wheel is connected to the rotor of the alternator such that when the weight is suspended on the wheel it makes it rotate.
Let us assume that the radius of the wheel is 50 cm.
Now we have,
Torque = (R)(F) sine(theta)
=> 14.5 = (0.5)(F)(1)
hence the force comes out to be 29 N
and now we can calculate the weight as
29/9.8 = 2.9 Kg
So i just want to ask whether suspending a 3 kg weight to the wheel generate 220 V electricity?
I have also seen that if any load is attached to the alternator the torque required to rotate the rotor also increases but i do not know whether the formula stated above by me consider it or not?
Please guide me.


texts: Powering a bbc micro:bit with coin cell batteries

texts:
Would it be possible to safely power the bbc micro:bit using coin cell batteries?  Out of the box it requires x2 AAA batteries, although an earlier prototype did use cell batteries.

I was wondering if connecting x4 3V CR2032 batteries in parallel would work? I believe this would increase the typical capacity to approx 900 mAh and maintain a 3V output.  Would this be safe if one of the cell batteries was faulty and discharged?  Would using rechargeable cell batteries in parallel reduce any safety concerns?

This is for a home hobby project.

Many thanks


texts: Output resistance of common-emitter amplifier

texts: Assuming the circuit here is correct, would the output resistance be Vout/Iout where Iout is Voutg0+VoutGc?


texts:
I've played with AVRs before with my atmel development kit and have seen recently the use of Arduinos increasing. I have a few questions from users:

Is it the same as using a microcontroller?
Are there any restrictions with the use of the Arduino instead of using the microcontroller?

I am interested in moving to them but also which should i get as there are so many to choose from.


texts: Firmware design for OBD2 - available PIDs request to ECU

texts:
According to many documentations, we can request a vehicle ECU to respond with the PIDs it supports. Link.My question is in the end.
I have designed an OBD2 scanner using STM32 and CAN. And it works flawlessly when I use the broadcast request ID (0x7DF) and request for individual PIDs (like RPM, Speed etc). But in this case, if multiple ECUs support a particular PID then my scanner will receive multiple responses for a single request. And so I decided to choose an ECU (not the broadcast ID). For this approach, we need to know the supported PIDs in an ECU and so I use 0x00 in Mode 1 (refer link).

Testing with emulator
This request when tested with an OBD2 emulator I was receiving an expected OBD2 frame. In which the data[0] is the msg-type [idicating if it's a CAN single frame, can consecutive frame or of any other type] data[1] is the byte that differentiates between PID response or DTC response. Data[2] is the requested PID value. And finally, the rest is the actual data bytes. Eg: A PID request 0x0c (RPM) has 2 bytes returned and so will have data2 and data4. And in my case I requested for PID 0x00 Mode 1 and got Data[3:6]. Because this was an emulator every PID was supported by the ECU.Bench testing my logic with the emulator worked.Received data:
Testing in a car
When I tested this same code in a car the response I got was not in accordance with what I received while testing. I tested for two cases: 1. Requesting a single ECU (0x7E0) for its supported  PIDs
2. Using a broadcast request (0x7DF)
In case 1
The response I received:

I can't understand what each of the bytes represents.

In case 2

Here the data received seems correct, except the fact that data[0] and data[1] is repeated. But the rest is correct, I checked the supported PIDs using a scanner I bought.
My questions
1. Am I only supposed to request for available PID using a broadcast request ID?
2. Why was the response from ECU 1 not in standard to other ODB2 frames?
3. If you have any experience or know of any project in which an OBD scanner was designed, could you share the link?

EDIT/PROGRESS
The above test was done for Maruti Suzuki Swift. Just a while back I tested the same code in a Hyundai Accent and I received the same response as seen in "case 2", i.e. I tried using broadcast and tried communication to the ECU directly, which resulted in a similar frame as seen in case 2 picture.
But still, I'm receiving two bytes with data 16 instead of a single byte with data 6. Any idea why there might be an extra byte? I'm not sure if I'm asking the right questions.


texts: Sensing signal from computer > triggering a MCU

texts:
I am to develop a system that senses an alert from a software running on the computer and triggered the MCU

In more detail, there is a program that is running on the computer that alerts the person with a really loud sound(like a siren), so what happens is this person could be away sometimes. so I need to find out when that alarm is going off and signal my MCU to do "it's thing"

The problem that I am having is how to make that triggering;
1- Reliable
2- Secure
so it won't go off by any other noise. I need to make it as easy as possible, do you think i have to write a program to read the sound card and triggers the MCU when the alarm went off or can I use a microphone, and analog sig. Find the Freq of the 'siren', and signal the MCU when it heard a sound in that freq from the computer?

Any help will be much appreciated


texts: Is 74LS139 a DeMUX? If yes then how can I give it input and select lines?

texts:
I am trying to learn DEMUX.

So, I have a 4 Channel DeMUX Diagram:

From this diagram we can clearly see that a DEMUX needs 2 Select Lines and 1 Input to give 4 output lines.

After that I have taken a look at the datasheet of 1:4 DeMUX IC 74LS139, which describes a diagram as shown below. Here is the link to take  a look at datasheet.

In second image we can clearly see that it has two input lines A0a and A1a on left DeMUX and A0b and A1b on right DeMUX. There is no select lines. Also we cannot see a logical connection between any input lines of Left and Right DeMUX.

Can someone explain me, how to use this IC as DeMUX?


texts:
In my house I have a climate system and I want to control the     modes using RPI. I'm not very strong in electronics so my question is - How can I connect RPI GPIO to this hardware X2 switch?

Like you see there is simple hardware switch with 13.5V in OFF state and 5mA current in ON state. Since there is small voltage and current I think relay or triac is too "hard" solution and I tested with NPN transistor  .Also I would appreciate advice on electrical safety .

but I'm not sure if it good schematic and solution...


texts: PIC 32 interface to Logitech force feedback USB joystick

texts: I am doing a project which requires interfacing the Force feedback USB joystick to a microcontroller, I came across pic32 which has USB hosting capability, now my question is: do I need to develop the device driver for the scratch or can i modify it from the existing to make this work? If so please could you provide the link for the same.


texts: Help with Voltage Divider driven NPN emitter follower

texts:
I am trying to solve the Exercise 2.5 in Art of Electronics. Use a voltage divider and emitter follower with 15V supply to make a 5V output, and within 5% of 5V at a 25mA load. This has been solved before in this forum: Designing a stiff voltage source using an emitter follower

They seemed to use a guess-and-test method for choosing the voltage divider resistors and I am wondering if there is a way to work backwards, saying that the emitter voltage is 4.75V with the 25mA load (worse case, 5% below the 5V target, and say a worst case beta of 30), to algebraically figure out the exact and most efficient resistors to choose to meet these requirements.


texts: How does electric current flow through a potentiometer?

texts:
I'm very new to electronics so I'm still grasping some of the fundamentals. I'm trying to figure out exactly how a potentiometer works and how the current flows through a circuit with a potentiometer in it.

In the picture, if I move the wiper (B) down - further from A - will the resistance increase (and hence voltage drop increase) between A and B meaning a lower voltage will be supplied to the power amplifier.

I'm trying to visualize the path that the current is taking within this circuit. Does the current flow as I have drawn on the picture in blue?


texts: LM317 - Getting the lowest possible Vout

texts:
The LM317 can produce a Vout from 1.25V to 37V. I have a small piezo pickup I'd like to step down to as close to 1V as possible. The formula for the LM317 is roughly Vout = 1.25(1 + R2/R1). Can I just omit the resistor on the adjust pin so that R2=0, therefore getting me 1.25V? Do I still need to provide a resistor on Vout so that R1 is non-zero?

Am I going about this wrong?


texts: output is affected by the next clock period

texts:
I am trying to write verilog code or or thinking about a circuit to do the function below.
In the clock period n, if there is a falling edge on S1 then OUT is high for the next clock cycle (n+1), if no falling edge  is detected then OUT is low for the next clock cycle (n+1).

Is this possible? Can anyone show me how to do this?


texts: How can I create a moped DC source from the alternator using the chassis as common GND for both AC and DC?

texts:
I need to convert from AC to DC the output of the red wire coming from the right stator coil (marked with R) which is the one that feeds the lamps.
The idea is to convert to DC then regulate the output to be able to use LEDs.

Figure 1. Honda PC50 wiring diagram.


texts:
I'm building a small sensor setup that is able to measure the transmission of light through a (clouded) solution.
I currently have a laser light that shines through the solution and a LDR on the other side. This works pretty well but there is quite a variation between batches of LDRs and the response is also not very linear.
Therefor I started to play around with a photodiode instead of a LDR. (The output is connected to an 12bit ADC)

Currently I have VTB8440BH photodiode connected to a LTC1050 opamp. It's wired up in a current-to-voltage setup and the photodiode in photovoltaic mode as depicted in the datasheet of the opamp on page 13. The sampling frequency is very low somewhere around 1Hz.

The opamp and photodiode will be placed in an environment with a pretty constant (+/- 1C) temperature of 60C. I read in the datasheet that increasing temperatures introduce increasing amounts of noise. I was wondering what the best strategy is to build this circuit, will this circuit that I showed here already be very low noise or do I need additional components to stabilise the output?

(Another small questions, what is the purpose of the 500K resistor between pin 3 (+) of the opamp and the ground? If I check the opamp calculator of Analog Devices (www.analog.com/designtools/en/photodiode/#/photoDiode) that resistor is not present)


texts:
I am very new to electrical engineering, only have been tinkering with Arduino and Raspberry Pi's in such an extend that applies to complete tutorials and smaller DYI's.

I am doing a part of an art-project and has been looking into schematics of how to make a LED-matrix.

I found a schematic that might suit the structure.

If I was to light up diode number: 2.2, 2.1, 1.2, I'd wanted to send power to the whole 1. and 2. column. Then I'd let 1. and 2. row be the GND and then the circuit consists. But doesn't that also light up the 1.1-diode?
How would i be able to make a matrix where the individual diode is being selected so that a Letter can be written? (fx R)


texts: LTSpice Syntax Error: function if(): requires exactly three arguments

texts:
This is a LT-spice Nestlist subcircuit code was found on a research paper. However, when I run a simulation on this subcircuit code, I keep running into error "Fatal Error: Syntax Error: function if(): requires exactly three arguments". I spent a long time in figuring out the cause of the error but failed. The only think I find is that it seems to be caused by the line defining F(V1,V2). The subcircuit code is the following. Can somebody help me to find out what's the problem with the subcircuit nestlist code and is there a solution to rewrite the code so that the error doesn't occur?
The code is following: I can't identify nor sovle the if statment error in this code.
.subckt mem_dev TE BE

.params a1=0.17 a2=0.17 b=0.05 Vp=0.16 Vn=0.15 Ap=4000 An=4000 xp=0.3 xn=0.5 alphap=1 alphan=5 xo=0.11 eta=1

.func wp(V) = (xp-V)/(1-xp)+1
.func wn(V) = V/(1-xn)

.func G(V) = if(V <= Vp, IF(V >= -Vn, 0, -An*(exp(-V)-exp(Vn))), Ap*(exp(V)-exp(Vp)))
.func F(V1,V2) = IF(eta*V1 >= 0, IF(V2 >= xp, exp(-alphap*(V2-xp))*wp(V2) ,1), IF(V2 <= (1-xn), exp(alphan*(V2+xn-1))*wn(V2) ,1))

.func IVRel(V1,V2) = IF(V1 >= 0, a1*V2*sinh(b*V1), a2*V2*sinh(b*V1) )

Cx XSV 0 {1}
.ic V(XSV) = xo
Gx 0 XSV value={eta*F(V(TE,BE),V(XSV,0))*G(V(TE,BE))}

Gm TE BE value = {IVRel(V(TE,BE),V(XSV,0))}
.ends mem_dev

To test the subcircuit, the asc file for the simulation testing circuit has the following code:
Version 4
SHEET 1 880 680
WIRE 256 304 -48 304
WIRE 256 320 256 304
WIRE 224 384 -48 384
WIRE 256 384 224 384
WIRE 224 432 224 384
WIRE 0 0 0 0
FLAG 224 432 0
SYMBOL diode 240 320 R0
SYMATTR InstName D1
SYMATTR Value mem_dev
SYMATTR Prefix X
SYMBOL voltage -48 288 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value SINE(0 0.5 100)
TEXT -64 24 Left 2 !.include Memristor.cir
TEXT 16 -16 Left 2 !.param initialY=0
TEXT -80 416 Left 2 !.tran 100m


texts: 220 volt step-down transformer with 6 secondary wires

texts:
I am an electronics novice. :)

I opened a working Casio vintage desk calculator (likely from the late 1980s/early 1990s).  It has a 220 volt step-down transformer with six secondary wires.  The two mains wires go into the transformer at the bottom.  The 6 wires come out from the sides (three on each side).  Following are the related images:

I found out continuity among the secondary wires as follows:

Purple-Grey-Purple: Continuity (side one)

Orange-Red-Brown: Continuity (side two)

However, the wires are wired to six separate contacts on the circuit board.

Are there differences in terms of voltage among each set of wires coming from the same side? If each carries a different voltage, how can I test this with my multimeter? I would appreciate guidance for using my multimeter safely/correctly.

If there are no differences among each set of wires exhibiting continuity, why were they wired separately?

Also, do the markings on the transformer mean anything?  There's also another, smaller marking (not visible in the images) that says "E41-2L11/2".

Update: The calculator has an integrated printer, and therefore a motor.
(Thank you TimWescott.)

Update: Calculator display:


texts:
I am designing a PCB with the ICS-43434, and would like to do, at least, some simple signal integrity simulations. I asked the manufacturer for impedance, IBIS or V/I curves, but they do not have that data available.
The PCB needs some distance between the mcu and microphone, probably 30cm. The SD clock speed is about 3MHz.
I will connect the SD pin to the MCU input using a 50 ohm pcb-trace line, but how do I simulate the output impedance of the SD pin. ?
From the datasheet, the digital output is specified as below.


texts: Reset Port Identifiers in Altium Designer

texts:
Lately I have been working on a new design in Altium (a derivative of my last ARM board) but I have run into a problem. I am at the stage of compiling the schematic documents and checking for discrepancies before making the PCB document and routing.

I am getting the error where the the identifiers of schematic ports do not match up with the corresponding port. I can seem to find a way to globally reset the identifier values inside the properties of each port. Does anyone know how to do this?

At my job this past summer we used ports in lieu of net labels it may be bad practice but it worked flawlessly with the designs we did at work. I've spent a while searching for an answer online as well as manually searching the Atlium menus but have not found a solution, if anyone knows I'd appreciate it, if I should just redo the whole thing with netlabels then I'd like to know about that to.


texts:
I'm trying to design the isolated SMPS circuit. I'm a newbie on power electronics and I'm using a circuit design tool to design SMPS. I have confusion about grounding and earthing. My system will have a PE(Protective Earth) connection but I'm not clear to where I must connect it?
The auto-created circuit designed by the tool is below.
As schema shows that Y1/Y2 safety capacitor is connected through the rectifier ground (I called it Primary Ground)

I got and SMPS and investigated the circuit. They connected safety capacitors to PE not to Primary Ground. And they made connection between all grounds and PE by other safety capacitors.

Which way to I use?
As I guess the auto-created circuit for Class 2 applications. My design will be Class 1 (PE connected) so I must design something like the second one. I need expert advice about this grounding issue.


texts: Recover battery management system for screwdriver without external power

texts:
I used one of many (Battery Management System) BMS on the marker to convert my Ca-Ng battery to Li-ion one.
An example: this

When bit is stuck or when you want to fixate a drill on drilling position you can trigger safety mechanism and BMS will disconnect your screwdriver from the battery. I suspect that this is over-current protection. And I am very happy it exists rather than burning motor.
But drawback of this is that to recover to normal operation mode i need to connect BMS back to an external power source, even for a second to unblock protection circuit.

On another screwdriver I have (branded, Li-on) when drill is stuck or other over-current activity happens power will be disconnected but in less then 1 minute screwdriver is operational again without any extra actions.

What can be done to implement such functionality? I suspect that there should  be some sort or multiple-use (thermo-)fuse that would recover on its own?


texts:
I have been working on a circuit design that would allow me to charge my iPhone/iPod classic 120 GB from my car. I am going to use power from the back of the cigar lighter sockets and put it into this circuit.

The plan is that it will step the voltage down the a usable charging voltage for the iPod.  I have also had to use a voltage divider to provide power to the D+ and D- pins on the USB plug, apparently the phone will not charge with out it.

There is also an audio out section there that will basically use the GND, L Audio and R Audio and this will be wired into a 3.5 mm plug to go to my car sound system.  There is also a 1 M Ohm resistor going from pin 21 on the iPod to GND to tell the iPod to shutdown when power is lost.

I am unable to breadboard this ATM as I don't have the voltage regulator or any rated capacitors.  I have drawn up the breadboard design with Fritzing (see below). Now to the question, can anyone see any issues with my design? I am a little worried about how hot the LM7805 will get and also concerned about if the common ground is going to mess with my audio? For reference here is the iPod Pin out.

Breadboard  layout

Schematic

Parts list

12-14v power   Car Battery
C1             4.7uF 50V Electrolytic Capacitor
C2             0.1uF 50V Electrolytic Capacitor
J1             Generic female header - 10 pins (Ipod)
J2             Generic female header - 3 pins (Audio)
LM7805         LM7805
R1             1MΩ Resistor
R2             47kΩ Resistor
R3             47Ω Resistor
R4             150kΩ Resistor
R5             100kΩ Resistor

PCB layout


texts: Flash programming for a custom design with SAME70

texts:
How can I add flash programming capabilities to a custom-design board witg the SAME70 or SAMV71?  For example, with the UC3-A3 (AVR32), I just expose TDI, TDO, TCK, TMS, RESET, GND/VDD, and voila: I connect a JTAG programmer and done.  This option seems to be unavailable with the SAME70/V71.

What would be the equivalent for these SAM Cortex-M7 microcontrollers?  The datasheet is non-explicit at best.  I would seem that I need to connect the SWD interface as shown in Figure 60-1 or 60-2 of the SAME70 datasheet.  However, every reference to this SWD feature (including the description of the SWD tag in electronics.SE.com !!) mention debug and test only.  The evaluation board uses EDBG via USB, but that does not seem like a viable option for a custom design.

Any tips or pointers will be appreciated!


texts:
Is this an active or a passive circuit?
Is this an active or a passive circuit?


texts: Can 12V car windshield wiper motor be powered using PC power supply?

texts:
As title says, can 12V car wiper motor be powered using PC power supply?
According to amperage of typical car wiper motor I would say yes, but I want to check :)
Thanks in advance


texts: How to strip pieces of insulation in a wire?

texts:
I would like to strip some insulation from a wire (like shown in the image below, the green area should be only the metal inside, no insulation). I was wondering how I could possibly do this. Cutting at both edges (of the green highlighted part) is no problem, however, how do I remove a the insulation that is now stuck in between the insulation. I was thinking about burning at the green highlighted parts, but would that be hurting my health if it heats up later on when the wire is being used?

I could not find anything on the internet (some people mentioning "multicore", but that leads me to other results), nor anything on this forum. I do not have extensive knowledge, I just do this as a hobby so please go easy.

I would like to connect some items in serie, so I therefore thought: Why not cut in between the wire and solder those to the pins. If this is wrong, please tell me.

EDIT:
As suggested, slicing the wire in the direction of the wire and then peeling it of seems to work. This is how it should look like:


texts: Identifying 4 coil 2 wire motor and run it from DC

texts:
Motor has 2 wires and 4 coils connected in series.
Rotating part with permanent magnet ring with 2 N and 2 S poles.

It does not rotate when DC-powered.

I want to make it rotating somehow without much requirements in torque and speed.
I prefer DC power. And if this is AC motor may be some simple alternating using H-bridge (L298).


texts:
I'm creating a simple circuit, where a microcontroller drives a piezo speaker. I couldn't find a datasheet for the piezo (the part number is HKDZ-G) but I know it has a internal oscillator and it's rated at 3V.

The speaker beeps are loud and clear 80% of the time. Occasionally, however, the sound will come out distorted (with a non-fixed higher pitch and lower volume, much like a teenager changing his voice). I can't really identify why.

This is the circuit schematic:

This is the circuit:

And this is the back of the circuit. The green wire is the one that leads from the MC to the speaker. While my soldering job is not so good, I tested all connections to see if their are not crossing. I also tried replacing the green wire (the photo is before the replacement) but with no success.

What causes the sound to come out distorted? Is it possible that there is some interference going on here? (I don't have an oscilloscope to test)

EDIT: I don't know if it's important to mention, but since the piezo has a internal oscillator, I'm not oscillating my signal, just plugging "1" on the MC pin output for a few hundred microseconds.


texts:
I notice that when downloading a footprint from Ultra-Librarian that it often includes a set of 3. When downloading the models for the ITS414N for example it includes three slightly different footprints: Sot223, Sot223-M, Sot223-L.

Are these footprints meant for different layers or are they alternatives based on the needs of the designer? If so, why should one footprint be chosen over the other?


texts:
Is the impulse response different from the output y[n]? Is the input x[n] all the delta function at different values of n?
From Signals and Systems by Robert Oppenheim, Linear Time Invariant systems


texts: Colliding fasteners in electronics retrofit project

texts:
I have a mechanical problem with securing a Mini PCIe card into an adapter which then goes into a legacy product's connector.

Look carefully at the orange PCB in the picture below and you'll notice that the screw passes through a cranked out "wing" that sticks out of the side of the adapter and fouls the pillar in the legacy product...

If I tilt the adaptor by 1.85 degrees or so then I can clear the pillar but I'd rather have the Mini PCIe laying parallel to the carrier board if possible.

Our normal method is to use M2.5 machine screws, nuts and washers, but in this situation an existing M3 pillar is colliding with the new M2.5 screw, so I need an alternative.

Is there a fastener type that can fit a pair of concentric M2.5 mounting holes but leave minimal material sticking out of the holes?

Notes:

There is almost no wiggle-room to move things around, the legacy device was never anticipated to have to support this new device and so I'm basically painted into a corner.  I have no more than 0.5mm freedom in any axis on any feature!
Doing it this way means I don't have to take the legacy device's threaded pillar out.  Removing that pillar would be a major hassle during the upgrade of hundreds of units.  With this hack I can reduce a 15 minute installation to less than 3 minutes!  But it is still a hack and that's nagging away at me.

Edit: @Transistor's suggestion looks like it'll do the job...

Might put a dab of silastic in the gap to stop it rattling :)

Final outcome: success!  Nice one @Transistor :)


texts: Audio voltage dimmer trickery! (Potentiometer not working as expected)

texts:
I'm a hobbiest with litte resources for parts, so I'm short on things I can use.

Therefore I'm trying to rescue an old amplifier's case and use it for a different project. The potentiometer on the front has got me stuck though. It's a slider style, with some weird trickery.

It has 6 pins. Four on the left, two on the right. Across the four on the right I get a linear taper but never much change in resistance. Across the far-apart pins (the ones coincidentally or not also in a parallel line geometrically speaking) give me a really weird audio-taper. The issue is: The frequency response is really low (cuts off high frequencies) and the sound isn't dimming how it's supposed to.

The pot changes resistance from 192k to 2.2 ish k. It never goes down fully.
I'm not sure if I need to replace this with a linear taper (as I like Linear better for sound myself as a personal preference) or if someone can help me get this working correctly.

I read about the voltage divider stuff and I'm not sure how to implement that as I do not understand how this potentiometer works.

Either way, if I can replace the pot to a nicer newer one (although the old one is of a brand like Porsche is to cars and mitutoyo to measuring instruments) and get it working correctly. THIS has had me STUMBLED for SO long!

Edit: Thanks Transistor for your input! here's some of the things you requested.

Here you can see the original layout. I may just be seeing something over the head however. Note: Any measurements with probes ACROSS the blue line are NOT connected. The both sides of the blue line are seemingly two different potentiometers.

I will measure the resistances in the morning. It's a quarter to five here.

Oh and voltage divider: If I ground half the signal isn't that kinda like a small short circuit?

PS: If you'd like any more explanation on something specific or any pictures, feel free to let me know. I'm all about that helping.


texts: Setting a Motor so that it spins at a certain RPM

texts:
I'm making a record player for a school project and I'm having trouble with the motor that will spin the platter.
I'm using a belt drive system, so I have two circles connected by a pulley system. Using the velocity ratio and pulley formula (knowing that the platter had to have a diameter of 100mm and spin at 33.3 RPM, and the motor spindle would be 5.55mm diameter) I worked out that the motor would have to spin at exactly 600 RPM.

I have no knowledge in electronics so any help would be massively appreciated. Could you please suggest a way I could buy a motor online and a way to control the motor so that I could get it to spin at exactly 600RPM? I've been looking at motors like these and adjustable motor speed controllers like these but I am unsure what motors would have the right voltage and amps, and whether the variable controllers would be compatible with them?

If anyone could suggest a combination of motor, and an adjustable motor speed controller and possibly even a way to put them together I would be so grateful. This is for a school project to finish.


texts: Input stage for ADC with operational amplifier

texts:
I am trying to make a voltmeter with a 10-bit ADC. The ADC can measure only positive voltages so I have made an input stage with Operational Amplifiers.

The idea of the circuit is to transform any negative voltage to positive. V1 is the voltage output and V Detect is 3.3V or 0V if the input signal is negative or positive, respectively.

The input frequency will not be more than 200 KHz. Will this circuit work ok whit the TL084? Is there any special parameter I should take into account?

Also I need V1 not to exceed 3.3V, will a zener diode work or it will cause any problems with regards to capacitance? I know ADC are very sensitive to any external capacitance because of the internal sample-hold capacitor they have.


texts: How can I control high voltage signals? (1 to 15kV.)

texts:
I'm an embedded s/w guy, but I'm able to do low voltage circuits without too much trouble. So I will try to ask this question on high voltages!

I've got a power supply running at 1 to 15kV. It runs constant voltage, always on. The power supply provides a charge for ejecting water droplets. See this video to see what I'm talking about: http://www.youtube.com/watch?v=5h8I6J_p6AM

I need to control the charge (on or off) for the electrode. What approaches might work?

Spec wise: 1-15kV, KHz-level frequency for switching.

Here's what I got brain storming wise:

Control from the low voltage side. Don't apply an AC signal to the
transformer. (But currently using off the shelf PSU.)
IGBT. They're on the expensive side the higher max rating. Also seem
to be focused on high current applications. And apparently they
can be slow (haven't gotten very deep with the specs).
Cascode. I saw some circuits and papers that seemed to suggest I
could use this approach, but there is a lot I don't understand.
Some kind of virtual ground method? Say 10kV and 9kV. (AC coupled
control signal?)

This is a beyond my abilities. Some thoughts would be very useful. :)


texts:
I have a two-coil LVDT where the position of the rod relates to a level of vacuum.
I excited the LVDT with a 2V ptp AC sine wave and measured the Vrms in (700.6V per Picoscope) and Vrms out to calculate the coupling ratio k. The value of k varies depending on the vacuum with a value of 0.498 when there is no vacuum.
I also measured the resistance and inductance of the two coils with no vacuum.
Here is the spice circuit. I have set the coupling ratio to 1.0 because if I set it to 0.498 the output Vrms is very small. This made me think that when using the coupling ratio in Spice I need to make the inductance of both coils the same. Is that right?
The simulated input waveform is a 2V ptp AC sine wave. With this simulation I get an output with Vrms of 322mV which gives a k value of 0.467. I expected to get a value of 0.498. The simulated value of 0.467 corresponds to more than 15inHg of vacuum which is the other end of the scale for this LVDT.
Do I have a flaw in my approach?
Is there a way to improve the accuracy of the simulation?
Thanks!
UPDATE - I have found that if I change the load from 500 Ohms to 1.6k then I can get a matching output. But what does this mean? Am I making the simulation meaningless or am I matching the load of my scope?


texts: Wrong pin configuration of LM317 and LM337

texts:
I have a problem with the circuit i was given
it seems that i made my circuit connection wrong. the pinconguration of LM317 and LM337 are on the left picture with 1-2-3 while i am suppose to connect it to the circuit but its required to have 2-1-3 connection, how can i connect the LM317/LM337 is there some sort of hold of transistor that can swith the 1-2-3, into 2-1-3


texts:
Could somebody explain how an FTDI chip converts USB signals into JTAG signals please (is that a correct statement)?

On the development board for my micro-controller the USB connector goes to the FTDI and JTAG signals come out of a port and go to the chip.

I thought FTDI only converted USB to the UART.

Thank you


texts:
After being fine for several days and picked up after transport, I found that one part of the Altera DE2 display is not working, you see where it is a 9 there should be an 8 so it is just like that part should be lit be isn't and that part of the display always fails to light:

So it fails the test, should I try and contact Altera for a warranty or something since the board is brand new? Any ideas? I think everything seems that the fourth unit from the right is broken in the southwest position. Do you agree?

There are ways to programmaticly light that part of the display as described in the manual but I didn't try, is that any idea if it fails the test? It is broken isn't it?

Update

after some more tests and contact with the supplier's support and sales, the supplier has decided to send me new parts i.e.

Part No.    Description Quantity    Reference
MDL-3015-ELG    7-Segment (Common Anode), RoHS  5

Do you think this will work to replace the faulty part? How do I replace the part once I've gotten it from the supplier?

Update 2013-07-29

I took it to a computer shop and they could solder on a new segment and now it's working. I'm real glad. Now I got two FPGA and I'm going to contact Altera if they want the DE2-115 back since all my development is for the DE2.


texts:
I am starting a project up at the moment, where i need to develop a metal detector for tracking purposes. In other words, i need the ability of knowing exactly which direction the metal is being dragged with basis from the metal detector.

Basically the image above explains my "idea", if its feasible or stupid is something else.
It should be possible to drag the metal in any direction (360 degrees).

Is there a different approach to detecting the absolute direction of where the metal is being dragged towards or does this seem possible?

EDIT: Omni-directional metal detection


texts: How to debug a transmitting configuration?

texts:
I'm using a CC1101 radio to communicate with an existing protocol. The settings I've used to configure the radio seem sound, as I'm able to receive messages from the 'other end' without errors. My returning transmissions, however, are detected less than 20% of the time. The receiving end has a debug option that shows all data received after detecting a start-byte, and when a start-byte is actually detected, the data received is correct. The amount of detected start-bytes is far too low, though.

I've confirmed my own transmissions are occurring when they should using a logic analyser, a spectrum analyser and an oscilloscope, but I can't figure out why my answers aren't detected. Other devices communicating with the receiving end do so without any problems.

How can I debug my transmitting configuration? Specifically, what steps can I take to rule out potential problems?

Details:

I've tried tuning the following settings, to either no effect or worsening the problem:

Deviation
Frequency
Number of preamble bytes
Transmit power

I've also implemented the CC1101's FREQEST feature, which required me to filter values beyond a certain threshold to prevent disabling reception altogether.

The datasheet seems to elaborate far more on reception than it does on transmission, which, in this case, isn't very helpful either.


texts:
I'm developing a measurement application with the TI MSP430 and I would like to hear some suggestions on what type of memory I can use.

The idea is to use it for logging during a certain time and then download the data to a PC when the device is connected via USB. The estimate is to hold up to 5MB of data, every sample being around 25 bytes of data.

Would a simple EEPROM chip do or is there something better out there?


texts: What are the highest DC and AC voltages or currents that can be considered as safe?

texts: By safe I mean safe for us when we touch a wire that is not insulated. I have heard that human body resistance is normally 50k Ohm when dry and 20K Ohm when wet. Therefore, these voltages or currents should be safe for a person who is wet. It should be considered when no insulator is present to protect the body.


texts: Could an ELM327 usb to serial interface be used instead of a D+K Can Interface?

texts:
I have an elm327 20 pin cable(uart) to usb interface,but it doesnt work with INPA that is a BMW diagnostic software,
I wonder if I could manage to use it as a D+K Can with some sort of minor changes.
Since both ELM327 and K DCan cables are doing the same job (uart serial to usb) as far as I know, I guess there should be a way to convert them to each other.(Hypothesis : these cables just do a serial2usb data conversion and nothing more!!, May be the hypothesis is not right)

ELM327 is an OBD II COMPIANT interface which is based on FT232RL chipset.

OBD Standard : Every car company support this standard to deliver diagnostic data to a hardware/software connected to ECUs m, since 1999
OBD II background

INPA : is a diagnostic software that is specially developed to work with vehicles produced by  BMW company.
Ther is a lot of INPA compatible cables on the market.


texts: Why is this potentiometer and comparator circuit not working?

texts:
I'm quite new to electronics and I'm afraid I'm missing some basic knowledge. (also please forgive me if I'm not always using the right terminology)

I'm trying to use a potentiometer (R1 in the schema below) to divide input voltage and divide it between the two other terminals.
The idea is that when the wire to comp1 has almost no resistance, the LED1 will light up. When moved to the other end, LED1 should be unlit when the voltage drops to a theoretical 4V (that's what the voltage divider connected to both V- terminals of the comparator is for).
When the voltage for comp2 is higher than 4V, LED2 should be lit.

When I create this on my breadboard, none of the LEDs will light up, no matter how I position the wiper of the potmeter.

What am I doing wrong?
Is it wrong to use the 5V for both the Vcc of the comparator and the "logic voltage" for its pullup resistor?

simulate this circuit – Schematic created using CircuitLab

EDIT

I implemented this circuit as follows:

The yellow wires are connected to the inverting inputs of the comparator, the blue and orange wires are meant to distinguish the circuits for both LEDs.
The grey and black wires are connected to the potmeter.

(btw I see I've placed the resistors "after" the LEDs, but I don't think that would make any difference in this case?)


texts: Built difference amplifier "tail" vs. SPICE models

texts: I am working on a difference amplifier example lab 5L.1 from Art Of Electronics Hands on Lab Course (I am not a student). I simulated three types of "tail" circuits using SPICE. Then I built the three types of "tail" circuits using MMPQ3904 array for the Q1 and Q2 pair and discretes 2N3904 for the mirror and sink circuits. I see basically the same clean output in physical circuits for ALL 3 scenarios (no common mode noise on the output). However, in SPICE, as I assume is more correct, I see the "long tail" circuit with common mode signal on top of the output. The sink and mirror are clean in SPICE. I thought the physical implementation of the "long tail" would show at least some noise as well. Is that a correct assumption?


texts: 33 LEDs in parallel over-heating unprotected Li-Ion Battery

texts:
I'm flummoxed. I have 33 LEDs (17 "lagoon blue" and 16 white) wired in parallel on 22 AWG stranded stereo wire. Blue LEDs have 20 ohm resistor in series, white have 27 ohm. The circuit has a slide switch in-line and the whole thing is powered by a 3.7V Li-Ion battery.

I did this once before, no slide switch and only 21 white LEDs w/ resistors. My on/off was to unhook the battery. Worked like a charm.

In my current project the big changes are 1) 12 LEDs added 2) two different kinds of LEDs used and 3) slide switch added.

Now, when I put a protected Li-Ion battery in the circuit the LEDs only light if I insert the battery while the switch is in the ON position. Then, if I switch the circuit off, everything turns off...and when I switch it back on, nothing. I have to pull out the battery and put the switch in its on position, then reassemble for the LEDs to light. In addition, if I leave it on, two of the cyan LEDs start to turn deep blue.

If I put in the unprotected battery it will turn back on but the LEDs fade on slowly to full brightness, and the battery gets hot.

What is going on?

UPDATE
One battery is protected AW Li-Ion 14500 3.7V 750mAh
Other is unprotected UltraFire Li-Ion 14500 3.7V 1200mAh

UPDATE 1/16/18
FYI this is an LED hoop. I disconnected the switch and ran straight from AW battery. LEDs still change color from cyan to blue, but sounds like that may be a separate issue with my resistor choice. Hard to fix or test that now. I wired another switch and the same issue occurred. Here is a sketch not to scale.


texts: PIC Microchip TCP IP Lite Stack on 8bit Microcontroller

texts:
I'm trying to learn about ethernet communication on a PIC micro following application note AN1921 however I'm getting compilation errors which seem to imply that the Microchip TCP/IP Lite Stack implementation isn't compatible with 8bit microcontrollers, despite the advice note specifically being for that use case.
Examples of errors:
mcc_generated_files/TCPIPLibrary/tcpip_types.h:58:22: error: bit-field 'vlanId' too large (12 bits)
    unsigned int vlanId:12; // not PIC compatible
                 ^
mcc_generated_files/TCPIPLibrary/tcpip_types.h:280:14: error: bit-field 'version' has bad bitfield type 'uint16_t' (aka 'unsigned short')
    uint16_t version:4;
         ^
mcc_generated_files/TCPIPLibrary/tcpip_types.h:281:14: error: bit-field 'trafficClass' has bad bitfield type 'uint16_t' (aka 'unsigned short')
    uint16_t trafficClass:8;// this is a problem
         ^
mcc_generated_files/TCPIPLibrary/tcpip_types.h:282:14: error: bit-field 'flowLabel1stNibble' has bad bitfield type 'uint16_t' (aka 'unsigned short')
    uint16_t flowLabel1stNibble:4;

The confuguration I'm using is a Curiosity HPC dev board + PIC16F18875 + ETH Click, and using XC8 compiler with TCP/IP Lite Stack versions 2.1.1, 2.2.8 and 2.2.12 (all of which have the same errors).
Any suggestions? I could understand if the TCP/IP Lite Stack library contained errors, but to have a appilication note specifically describe how to use it with 8bit micros it really makes me think I've got something wrong? I am fairly new to this and starting to doubt that the thing that's meant to be helping me learn is actually making things harder.


texts: EMC conducted emissions go up if input cable is close to inductor

texts:
I am measuring conducted emission at the input of a SEPIC converter.

At first, the emissions are only about 45 dBµV at switching frequency.

But when I put my finger on the SEPIC (coupled) inductor, the emissions go up to about 65 dBµV (!).

Even worse, if I move the input cable close to the SEPIC (coupled) inductor, the emissions can go up to 70 dBµV.

If I stick a piece of copper foil on top of the inductor and connect the foil to GND, then the emissions go only up to 48 dBµV.

In a larger production, it is not feasible to use copper foil. Also, I cannot stop the cable from touching the inductor. Therefore:

What else can could be done to solve my problem?
How can this behaviour be explained?