texts: What is the speed that can be supported with 10G 1000 Base KR. I am trying to understand how many diff pairs are required for TX and how many for RX to support full 10G speed.


texts:
I recently installed an LED strip light to replace a fluorescent lamp in my garage.
It works great and I highly recommend them, however, I am curious why there is such a noticeable delay between turning on the AC wall switch and the thing lighting. I have seen folks on here before reporting a significant delay between application of AC power and lighting, and in my case the delay is close to a second.
However, I can't really figure out why the long delay. It's not LED turn on time, that ought to be a lot less than an incandescent bulb and I realize there is a constant current driver in there, but again, I'd think that would only take something in the order of tens of milliseconds to wind up.
So what else could be going on?
ADDED INFO
I played with it a bit more, turning the power off and on quickly I can make it stay off for over two seconds. I'm starting to wonder if these things have some smarts built in with significant delays to ensure stability of supply before LED activation.
Just wondering if any of our readers have some commercial design experience in this department and can shed some light on any higher design criteria that others, like me, might not be aware of. Perhaps safety or lamp life issues or some such.


texts:
I have a question about the details of microprogramming and hard wiring in CPU architecture.

In hardwiring, we write a code, the compiler translates it to the ISA, then the ISA is run in the hardware.

In microprogramming, we write a code, the compiler translates it to the ISA (which is much more complicated than the ISA in hardwiring), then a device (I don't know the name) translates it to the hardware language.

Am I correct?


texts:
In a DC circuit, current starts to flow, and some time is needed for current to stabilize based on the time constant, there is EMF induced due to current changing over time.

As soon as the current stabilizes there is no longer EMF due to self inductance?


texts: What typ of Diode would I use ? I don't know much about Electronics.

texts: I have a motorcycle that is running a 12V system. My question is, What type of diode would I use for my cooling fans for my radiators. The power comes from the ECU on my bike. I want to install another positive wire and switch to the end of the power wire on the ECU power wire and a switch so I can keep the fans running even when the ECU turns off the voltage to that system if need be. The Power wire is connected to a relay and then on to the fans. I would like to Have the switch power in the same line just before the relay. I hope someone can understand my crappy explanation.


texts:
I designed a USB dual host based on a FTDI's VNC2-32L1B. I'd want to protect its firmware from being read/copied cause it contains pretty sensitive data (private keys, etc.), but the VNC2 has no read out protection option at all - everyone who has a debugger interface is able to download the flash image.

So my question is wheter is there any hardware or software possiblity to protect the chip from readout? I've thought about cutting out the programming pins and writing my own bootloader, but I'd prefer a simpler or (perhaps) better solution.
Thanks in advance for any ideas.


texts: Issue with avr spi slave interrupt in proteus ATmega8

texts:
I want to get some data from spi, but spi interrupt doesnt work. I get a message and a pause in proteus instead of a signal on LCD. How to fix this?
My code:
void spi_init(){
    DDRB = (1<<PINB4);
    SPCR |= (1<<SPIE) | (1<<SPE);
}

ISR(SPI_STC_vect)//
{
    str_lcd("            ");
    setpos(0,0);
    str_lcd("SPI"); //signal
    setpos(0,0);
}

int main(void)
{
    spi_init();
    sei();
    while(1){}
}


texts:
I found the following circuit which acts as a "retiming flip flop". A similar version exists which uses the CLEAR (instead or PRESET input), data tied to VCC (instead of GND) and output taken from \$Q\$ (instead of \$\overline{Q}\$).

simulate this circuit – Schematic created using CircuitLab

How does this circuit exactly work? The truth table of a flip flop with asynchronous reset is (here given for the NL17SZ74):

Specifically, the clear (or preset) inputs are asynchronous and hence affect output immediately, independently of the state. Only when \$\overline{PR}\$ and \$\overline{CLR}\$ are both high, the flip flop responds to the edge of the clock and works as a flip flop.

How does this flip flop synchronize the CTRL0 signal to the clean clock?

Second question: Is there a preference between the two versions mentioned (the one shown in the circuit vs. the one with \$D\$=GND, \$\overline{CLR}\$=Input, \$\overline{Q}\$=Output)?


texts: How did rotary converter commutators conduct electricity?

texts:
I've been reading about rotary converters and examining photographs, but I've noticed that nearly all have a very strange (to me) commutator design. It looks like a piece of wire screen rather than solid commutator plates. Compare:

rotary converter commutator vs a normal motor commutator

It doesn't seem likely to me that a commutator could have so many connections, or that a continuous metal screen connecting all the brushes could be of any use. How can such a setup conduct electricity to/from the rotor windings? The mesh/screen thing definitely spins; see this video.


texts: tracking error state space, linear control example

texts:
I am trying to understand a detail from an example, from the control textbook Slotine and Li (1991) "Applied Nonlinear Control", Prentice-Hall, Example 6.4, pag. 220. A linear system is given:

$$\eqalign{
   \left[ {\matrix{
   {{{\dot x}_1}}  \cr
   {{{\dot x}_2}}  \cr
 } } \right] =& \left[ {\matrix{
   {{x_2} + u}  \cr
   u  \cr
 } } \right]  \cr\\
   y =& {x_1} \cr}
$$

where the output \$y\$ is desired to track \$y_d\$. Differentiating the output, an explicit relation between \$y\$ -output- and \$u\$ -control input- is obtained:

$$\dot y = {x_2} + u$$

Until here it is clear. Now, the authors choose a control law:

$$u =  - {x_2} + {{\dot y}_d} - (y - {y_d})$$

and say that this yield the tracking error equation:

$$\dot e - e = 0$$

with the \$e\$ being the tracking error, defined as \$e=y-y_d\$ and the internal dynamics:
$${{\dot x}_2} + x = {y_d} - e$$
... and the problem continues.

My question is: how does one define the control law \$u =  - {x_2} + {{\dot y}_d} - (y - {y_d})\$ ?? And how does this relate to the two following equations (\$\dot e - e = 0\$ and \${{\dot x}_2} + x = {y_d} - e\$)?

Any clarifying answer is much appreciated.

Thanks


texts: Input Capacitance in LM 2596 Step Down voltage regulator

texts:
What is the significance of the input capacitance (680 uF) (uF = microFarad) at the input of the LM 2596 ? LM 2596 is step down voltage regulator.

Please refer:
http://www.ti.com/lit/ds/symlink/lm2596.pdf

The 680 uF (microfarad) capacitor is the leftmost capacitor on the circuit on page 1. Usually to 'kill' the high frequency noise from supply voltage 0.1 uF is used. I am sure 680 uF serves different purpose. What is that ?

Any intuitive explanation would be great.


texts:
I made a circuit for LED Driving (current controlling), based on
this circuit. Everything works fine except that the LED is suddenly blinking when the circuit is turning on and off. How can I prevent
this blinking?

I can't calculate the blinking current but I  think it is about 10-20 mA which is very high for me and can damage LED.


texts: If a transistor is in the "active" region and the current to it's base -> emitter is reduced, will the resistance between collector -> emitter increase in a proportional way?


texts: How to drive high voltage transistor with low voltage op amp?

texts:
I'm trying to drive a darlington pair with 24 V collector voltage with an low voltage op amp. I tried adding a PNP transistor so the op amp just have to drive that single transistor, but haven't had any luck.

simulate this circuit – Schematic created using CircuitLab
How can I drive the transistor with low voltage op amp? is it even possible?


texts:
For background I am not an engineer, and reading about linear predictive coding, so this question may be very trivial.

I am trying to understand what a textbook means by referring to something as an "all pole source".

It says that speech (in the frequency domain) is not typically an all-pole source because there are zeros present in the spectrum due to glottal pulses and the physiology of the vocal tract.

As I have looked into this, it looks like "poles" are when an equation (transfer function?) blows up to infinity, and "zeros" are when it approaches zero. The textbook says that there are both poles and zeros present in a spectral representation of speech. Does that mean the energy present in the spectrogram? If this is so, there are no times when there is infinite energy, and no times when there is an absolute loss of energy, so I find this pretty confusing...

Given that context, my question is this: what does an "all pole source" mean in this context? And what does it mean to have poles and zeros in a spectral representation of human speech?


texts: Setting correct operating frequency for LLC resonant SMPS

texts:
I need to figure out if an LLC half-bridge resonant SMPS is designed (more or less) correctly.  I am not an SMPS designer, and neither is the manufacturer, so I'm just reading a bunch of app notes and learning what I can.  It's producing ±35 V 400 W from a constant 400 VDC PFC output.

As I understand from my reading:

The resonant frequency is a property of the LLC transformer network, increasing with load from fp (unloaded resonant frequency) towards f0 (shorted resonant frequency).
The switching frequency is controlled by the driver IC, and decreases with load to regulate the output by riding up the resonant gain peak, getting closer to resonance and increasing the output as the load increases.
The switching frequency must never drop below the resonant frequency at any given load, or it will enter capacitive ZCS mode, which is Bad.

Is this all correct?

They've set the switching frequency to always be below f0.  They claim this is ok, because Fairchild AN-4151 says you can do above or below resonant operation:

  "Below resonance operation is preferred for high output voltage applications, such as Plasma Display Panel (PDP) TV ... above resonant operation ... can show better efficiency for low output voltage applications, such as Liquid Crystal Display (LCD) TV or laptop adapter"

Would 70 V out be considered low or high voltage in this case?  I'm guessing high voltage means hundreds of volts, so this is low voltage.  So does that mean it would ideally be operating always above f0?  Maybe as long as point 3 is met (ZVS mode), it's not too important?  This article says:

  Most of these converters are operated above resonance so that at light-load conditions the switching frequency is higher than the resonant design points (region 1) [fs > f0]. As load increases, the switching frequency droops. At maximum load, the converter operates slightly below the LlkCr resonant point [fs < f0] in region 2 [but should never enter region 3].


texts:
1) I have a project to build a time clock based on the TDF signal on 162kHz, from Allouis, France. The time coding is similar to DCF-77 so I will send it to an Arduino with proper code. I managed to build an antenna and i can get the phase modulated signal but I don't know how to demodulate it ?
Any help would be apreciated.


texts: Is silver actually used for coating copper wire?

texts: I heard stranded copper wire would be silver-coated for better conductivity at high frequencies (skin effect). But silver is at least an order of magnitude more expensive than copper, yet only has 5% more conductivity. Is silver actually used for this?


texts: How to reduce noise in SMPS (Switching mode power supply) circuit

texts:
I am just using a reference design of SMPS (from Microchip) to boost input voltage from 12V to 90V as the image below:

It's working normally but the problem is the noise at the output of 90V.
I measured the amplitude Vpeak-peak of noise around 150mV and the repetition frequency is 110kHz = switching frequency of HV9110 controller.

My question is how can I reduce this noise to 20mV because it will affect on my signal analysis.

Please help me and thanks in advance!!!


texts: MCP23017 INT Pin always high - INT cannot be cleared

texts:
trying to enable INT on MCP23017 so that, in case of a state change on any PIN from Port A (e.g from low to high) an interrupt should be triggered on INTA.
Unfortunately the INTA pin remains high as long the pin on port A is high. So I can not clear the INTA pin
What I have done so far. Requirement is to use pure CMD and no framework for it.
I took i2cset and i2cget tools from raspberry pi 4.
wrote a simple script for configuration and added an oscilloscope to INTA.
#!/bin/bash
i2cset -y 1 0x20 0x00 0xff # all ports bank A to inputs
sleep 0.5
i2cset -y 1 0x20 0x0a 0x02 # set Bit 1(INTPOL) to HIGH
sleep 0.5
i2cset -y 1 0x20 0x08 0xff # set Bit 1(INTCONA) to HIGH
sleep 0.5
i2cset -y 1 0x20 0x04 0xff # High on all pins to enable all pins to interrupt on a change of polarity (i.e switch change)

After executing the code, the level on INTA is low.
Adding a high level via cable (so connecting +3.3V to any pin of the port A ==> all pins are wired via 10k to GND) to a pin of PORT A triggers a high level signal on INTA.
It goes back to low if also the high level on the pin from PORT A disapears.
No way of resetting (clearing) the interrupt via CMD like
i2cget -y 1 0x20 0x10  # ==> this is always showing the pin who was triggering the INT
or
i2cget -y 1 0x20 0x12 # ==> this is always showing the right state of the inputs (so which pin is high and which is low... )
Any ideas what's wrong?

I am using IOCON.BANK = 0 therefore IOCON Register for Port A should be according to table 3-5 IOCON Address=0x0a.
According to datasheet the bit 1 should be set to 1 or 0.
In my top post I think I must have a bug.
i2cset -y 1 0x20 0x0a 0x02 # set Bit 1(INTPOL) to HIGH

I must set it instead of 0x02 to 0x01 but how can I define to set exactly the bit 1 to value 1?
i2cset -y 1 0x20 0x0a 0x01 1 # ????? that does not work :-(


texts: Are Lithium Thionyl Chloride Battery usable in my vibrating environment? Are they safe?

texts:
I have to power a circuit subject to constant vibrations (10-15 Hz with an amplitude of ca 10 millimiters) with a battery and I was thinking of a Lithium Thionyl Chloride Battery.
The circuit has to be attached under a vibrating table.

The circuit is made of an accelerometer and a gyroscope (MPU6050) with a bluetooth module (HC-06) all smd-soldered, and the battery.

The circuit is going to sample and send data I get from an accelerometer and a gyroscope to an Arduino through a Bluetooth connection (once every hour, then I enter in power-saving mode and switch off the sensors).

I found many batteries online around 7,5 Ah that could theoretically power my circuit for 38 years (My max current consumption would be 30-40 mA only when pairing to the Arduino; in normal circumstances the power consumption should be around 8 mA)

Are they safe in my vibrating environment?
I am going to pot the circuit, so also the battery will be potted with the rest of the circuit.
Is it going to have problems with that?


texts: Li-ion 3s Battery Charger with Load Sharing

texts:
I am requesting help to create a battery charger and load sharing circuit with the following specifications:

3s Lithium Ion battery
12 V at 2 Amps to power TPA3128D2 Class-D Amplifier (this is for max volume. Possible to lower the voltage/current to accommodate design constraints)
2.7 V at 50 mA, low noise to power STM32F4 microcontroller as well as external DAC and analog circuitry
Charging done via USB Micro-B port with USB 2.0 (5 V at 500 mA or 1.5 A)

I am currently considering this design:

Power Circuit Module to handle battery charging and balancing.
BQ25713 to handle the load sharing/power path management as well as 12 V boost converter
TPS62125 to output the 2.7 V from the BQ25713 power path
BQ24392 to handle USB charge detection/enumeration

I would appreciate any help on confirming or denying the viability of this design as well as any suggestions on any improvements that can be made for simplicity.

Edit: Simple block diagram as requested.


texts:
simulate this circuit – Schematic created using CircuitLab

Suppose I have a series RC circuit with a current source.

The function of the current provided by the current source is:

$$I(t) =
\begin{cases}
I_0  & (0\text{s}\leq t \ (\text{mod}\ 2) < 1\text{s})  \\
0 & (1\text{s}\leq t \ (\text{mod}\ 2) < 2\text{s})
\end{cases}$$

According to the current function, voltage across resistor is \$V_R=I_0R\$ and voltage across capacitor is \$V_C=\frac{\int_{0}^{t} I(t) dt}{C}=\frac{I_0t}{C}\$, when \$0\leq t\leq 1\$.

I have two confusions regarding this circuit:

According to Kirchoff's voltage law we need: \$V_R = V_C\$ i.e. voltage drop across resistor is equal to voltage drop across capacitor.

That is, we need \$\frac{I_0t}{C}=I_0R\ \implies t/C=R\$, which is obviously not true since \$R\$ is constant. So, where am I going wrong?

I think that to make Kirchoff's voltage law hold I need to consider voltage drop across current source too. But, I'm not sure. Anyhow, are my expressions for \$V_C(t)\$ and \$V_R(t)\$ correct?
In this kind of a circuit the voltage across capacitor \$C\$ will keep increasing with time, according to the equation \$\frac{\int_{0}^{t}I(t)dt}{C}\$. Is this practically possible?


texts: At what currents should NI-MH batteries be charged?

texts: So I bought one of those cool chinese battery chargers that can charge any type of battery and in a lot of sizes. By default it charges it at 500 mA but i can be set up to 2000 mA. Is it safe to discharge-refresh AA and AAA batteries to 2000 mA to speed up the process?


texts: Heathkit SL-5798 Motion Sensor Wiring Diagram

texts:
The motion sensor was salvaged and has four wires:

Black
White
Red
Green

Only the sensor was salvaged.  The rest was discarded.

Is the convention black or red = hot, white = neutral, green control wire applicable here?  It would be nice to understand the voltage associated with the control wire (AC / DC and voltage range).  It would be sad if applying 120V AC were to damage / fry this sensor.

Any references or analytical techniques are appreciated.  Thanks


texts:
I'm looking to sample a 0 to +15 V analog input signal, and it is not sinusoidal, rather it is impulse driven.  I don't need to sample at a high rate (< 1kHz), but I need to sample over the full range of the signal.  The way I see there are two options:

Buy a more expensive ADC with a +/- 10 V range and try to bias the input to fit into that swing.  This would require two voltages supplies though I think.  I may be wrong though...
Attenuate the input signal to make the signal swing fit in the range of normal low-cost ADCs

While 2) seems more difficult in the design, it certainly seems to have a better cost benefit based on what I've seen from Analog and Linear's offerings.

By attenuating the signal, do I risk losing anything though?  I was thinking that if the ADC has the same sample bit width as that of the larger swing ADCs, the samples could be scaled digitally in software so that it appears the initial signal voltages are sampled.


texts: How can U_CE be smaller than U_BE in this circuit?

texts:
Recently I was wondering why UCE can be smaller than UBE. I've drawn a small diagram with the typical values of the BC547 NPN transistor.

This amazes me all the more as UBE shares its PN-regions with UCE.

Can someone shed some light on this "miracle"?


texts:
So from what I understand transistors are one of the most important electronic elements for computers because of TTL (Transistors-Transistors Logic).

Is this true? If so, how exactly does this work? I have heard the terms "logic gate" and "logic block" tossed around.


texts: Choosing appropriate capacitor value from ripple

texts:
I have a H-bridge driving a 12V motor that at 100% duty cycle draws around 15A. To start the motor I am applying a soft-start, the duty cycle of PWM to H-bridge goes from around 60% to 100% and PWM frequency is around 500Hz.

How can I calculate the needed capacitor value on 12V for 10% ripple? At such high currents and low PWM frequency would it be better to go for more than 10% ripple (this 12V line isnt driving anything else than motor)?

I am aware of: $$I=C\times\frac{dV}{dt}$$
But plugging the numbers in I get: $$C=\frac{I\times dt}{dV}=\frac{15*\frac{1}{500}}{1.2}=25mF$$

Which seems quite high to me, is this correct?


texts:
We have an off the shelf display and touch screen (Projected Capacitive).

It has passed a contact test at 4kV but failed at 6kV.

Are there an measures that we can take to potentially improve the ESD protection without relying on the vendor of the screen?

It is currently in a metal box with just the screen showing.


texts: Can we use pir sensor while it's moving?

texts:
I fixed the pir sensor on the top of servo motor.while the servo motor's rotation the pir was also rotated by servo motor's motion.but the problem I had founded that pir sensor had always indicated  motion of human which I realized through a buzzer. When I take of the sensor from servo motor it had worked as well.
So my question is that can we use pir sensor while it's moving?


texts:
For a while I thought I could distinguish between USB 2.0 and 3.0 (or 3.1 gen 1) standars from the hardware point of view. Now I am confused however, because I have noticed that my USB 3.0 hub has the additional differential pairs contacts on its male plug (device side, goes to the host) but does not have them on its 4 USB female connectors host side, goes to the devices). At first I thought that this is a fake 3.0 hub, but the USB Tree Device viewer reports the connected devices through the hub are at SuperSpeed bus. How is that possible? I also did notice that connecting such hubs in series makes the last device in the chain to nor support SuperSpeed anymore (at least this makes sense to me).

How is it possible that the USB 3.0 hub doesnt have the additional diff pairs for the devices and support SuperSpeed anyway?


texts: TL431 - negative and positive references point

texts:
I am a musician who likes to play around with electronics.
For some synthesizer circuits I am working on I need to create two references points using the TL431 - one for negative 2.5V and the other for positive 10V. I have a power supply of +-12V dc.
After looking around the web I came with these two circuits:

I checked both with DMM and both gave me the voltage references I needed.
There are two things I would like to ask in both circuits:

Should I add a resistor before the references points in order to limit the current? In the top circuit from the anode lug and in the bottom one from the cathode lug . If so what should its value be?
Can I use those references points at other points in the circuit without resistor?
I placed a 1.5k resistor from the power rails to the TL431 (in the top circuit from the -12V rail to the anode and in the bottom circuit from the +12V rail to the cathode) but I'm not sure why other then it was recommended to me earlier. I guess different values will limit the current that goes to and out from the TL431, but how do you know what value to choose?

Thanks!


texts:
I'm looking to replace the cable of a mains (UK 230V nominal +10/-6) appliance, essentially just a motor, rated at 180W.
The existing cable has a 3A fused plug; my options to replace it (restricted since I'm looking for a coiled type) are 1A or 6A. At maximum deviation on the supply, (and assuming the appliance draws a constant power) I calculate 180/224 = 0.8A.
However, I know motors can/do draw a high 'in-rush' current as they start up; I don't know whether this peak or the 'normal operation' is what's specified, nor whether that's standardised at all? (And I'm not really  equipped to measure it.)
Can I replace the 3A fuse & cable with 1A; or should I use the 6A (or look harder for a 3A or closer) variant?


texts: Higher KW on the secondary winding of a transformer

texts:
I have a step down 3 phase Delta/Wye transformer. 400 volts on the primary and 208 volts on the secondary. I have about 4 amps per phase on the primary and 13 amps on the secondary.

How is this possible? It should be around 8 amps on the secondary but the amperage has more than tripled. This means that the transformer is generating over 1 KW of power by itself.

Has anyone else seen this?


texts:
I'm using a 10kv ignition transformer for a jacob's ladder.

It works great! Currently though I've only tested it on its own circuit. But I would like to have this thing running in my lab. (I know not to run for more than a minute at a time due to ozone generation, and my lab is well ventilated)

However my lab is only one circuit, and I'm worried about the flyback from unplugging it harming my rpis, etc.

How do I isolate this thing / compensate for the flyback?

This transformer is old style, not like a solid state NST.


texts: Part number of a connector in an Asus laptop

texts:
While trying to repair a laptop, the connector linking the power button to the motherboard of a Asus x54h has burnt.

I am a software developer, I do not have very much knowledge in electronics, but I would like to repair that myself.

So I could change the connector, but I am afraid I may not have sufficient tools (just a basic soldering iron).
I could also just wire pins which power on/off the laptop.

What is the name of the connector on the motherboard? And also what are the ways to repair the connection?

Some pictures:


texts: Can my 3.2V LiFePo4 battery power my cell phone through the cell phone's micro USB port?

texts:
I have a large LiFePo4 battery cell made by Headway (model 40152S 15AH single CELL, 3.2v).  I'd like to use it to power my Samsung Galaxy S3 phone.  On the original phone battery it says that it is a 3.8v.  The phone has a micro USB input to charge the phone.

I bought a cable that has a Micro-B connector at one end.  I haven't cut it yet, but after cutting the cable I'm hoping that there will be about 4 or 5 wires, where one of them would be for the positive and one for the negative power.

Can I use this 3.2v battery to power the phone even though the battery that comes with the phone works with 3.8v? Will using just the two power leads be enough to make the phone work?

If my headway battery is too low of a voltage to work, would I need to use a 3.7 volt Li-ion battery instead?  Is 3.7v close enough?  I haven't been able to find any batteries that are exactly at 3.8 for a single cell.

edit after searching for a DC-DC Regulator Module:

I found a module that is designed to do this:

Step up DC-DC regulator
Designed for convert 1 cell Li-Ion / LifEPO4 battery pack to 5.0VDC output
Running / charging most popular 5.0VDC devices such as cell phone/MP3/MP4/PDA/iPod/PSP/GPS from Li-Ion / LifEPO4 battery pack

Input Voltage
2.0 ~ 4.2VDC  via "VIN+" / "VIN-" Soldering spot

Output Voltage
 5.0VDC 2.0A Max via USB Female Jack
5.0V 1.0A Max each

Will this module be enough to place between my 3.2V battery and the cable that I can use to go from the USB in the regulator to the micro USB on the phone?

Thanks very much for your help.


texts:
I have designed/cobbled together a small BT receiver for my vehicle which is getting some RPM dependent alternator whine due to stray A/C. Though I know this is likely an issue with the battery, the alternator or a ground loop, I would like to build a filter for the power input. I have a couple questions:

I am looking at the TDK ACM70V-701-2PL-TL00 common mode choke as an input filter for my D/C line. Would this be sufficient on its own, or am I wasting my time without adding a large capacitor to complete the LC filter?
If I absolutely need a large capacitor on the input, what's the smallest I could get away with? I'm trying to stay away from electrolytic capacitors due to their large form-factor.

Finally, here is schematic of the D/C input of my circuit:


texts: Why Johnson's noise is not uniform when plotted in log mode?

texts:
I have a 2 resistors of 1000 k each , I have connected them in series and biased one end with +9 V and other end with +9 V.

The output is taken from connection point of two resistors and I have given that to amplifier with Gain 20000 then to spectrum analyzer.

In log mode of operation I should get a flat signal which is independent of frequency (x axis) , but the signal is gradually decaying.

Does anyone have any idea where I am going wrong and what should I do so that the plot comes flat.


texts: Can the Arduino be used to "spy" on a UART connection between two devices?

texts:
I have a need to install an Arduino (actually just the IC) into existing hardware to enhance functionality.

What I would like to do is connect the Arduino so that it "spys" on the I/O lines between two chips on a board. If the Arduino picks up a specific keyword on that UART connection, it will perform a specific action on a separate set of output pins.

What I'm uncertain about is how to connect the Arduino in such a way that it can decode an existing UART connection without participating?  If not possible, I am interested in theories, ideas, etc.


texts:
I'm using the following eeprom FM25CL64
http://www.tme.eu/at/Document/f170062ad2f9464359d3dc53837256d8/fm25cl64ds_r3_2.pdf

I try to write data, read data by polling but it stays in infinite loop and the status register is always 0, and that's why I stay in infinite loop when I read the register.

here is my driver and here is how I use it

// extract a low byte from a 2 byte word.
#define Lo(X)   (unsigned char)(X&0x00ff)

// extract a high byte from a 2 byte word.
#define Hi(X)   (unsigned char)((X>>8)&0x00ff)
#define SPI_EEPROM_SELECT      0xFBFF          /* select EEPROM value */
#define SPI_EEPROM_DESELECT    0x0400          /* deselect EEPROM value */

#define EEPROM_CMD_WRSR        0x01            /* Write Status Register */
#define EEPROM_CMD_WRITE       0x02            /* Write Memory Data */
#define EEPROM_CMD_READ        0x03            /* Read Memory Data */
#define EEPROM_CMD_WRDI        0x04            /* Write Disable */
#define EEPROM_CMD_RDSR        0x05            /* Read Status Register */
#define EEPROM_CMD_WREN        0x06            /* Set Write Enable Latch */

struct  STATREG{
        unsigned    WIP:1;
        unsigned    WEL:1;
        unsigned    BP0:1;
        unsigned    BP1:1;
        unsigned    RESERVED:3;
        unsigned    WPEN:1;
};
union _EEPROMStatus_{
        struct  STATREG Bits;
        unsigned char   Char;
};

I'm using it with blackfin 533

void spi_eeprom_select_new(void)                        /* select EEPROM */
{
    *pSPI_FLG   = (*pSPI_FLG & SPI_EEPROM_SELECT );
     ssync();
}

void spi_eeprom_deselect_new(void)                      /* deselect EEPROM */
{
    *pSPI_FLG   = (*pSPI_FLG | SPI_EEPROM_DESELECT);
    ssync();
}

///////////////////////////////////////////////////////////////////////
unsigned char  spi_trans_byte_bw_new(const unsigned char tx)
{
   *pSPI_TDBR = tx;
    int i;
    while ((*pSPI_STAT & 0x0001) == 0) ;
    for( i = 0 ; i < 100; i++)
    {
    }

    unsigned char d = *pSPI_RDBR;
    return d;
}

// enable writeing to EEPROM
void EEPROMWriteEnable(void)
{
    unsigned char Local_8;
    spi_eeprom_select_new();
    Local_8 = spi_trans_byte_bw_new(EEPROM_CMD_WREN);
    spi_eeprom_deselect_new();
}

void EEPROMWriteDisable(void)
{
    unsigned char Local_8;
    spi_eeprom_select_new();
    Local_8 = spi_trans_byte_bw_new(EEPROM_CMD_WRDI);
    spi_eeprom_deselect_new();
}

// read status register
union _EEPROMStatus_ FM33256readStatus(void)
{
    unsigned char Local_8;
    spi_eeprom_select_new();
    Local_8 = spi_trans_byte_bw_new(EEPROM_CMD_RDSR);
    Local_8 = spi_trans_byte_bw_new(0);
    spi_eeprom_deselect_new();
    //printf("status %x\n",  Local_8);
    return (union _EEPROMStatus_)Local_8;
}

// write a byte to address (16 bits)
void FM33256write8(unsigned char Data, unsigned int Address)
{
    unsigned char Local_8;
    EEPROMWriteEnable();
    spi_eeprom_select_new();
    Local_8 = spi_trans_byte_bw_new(EEPROM_CMD_WRITE);
    Local_8 = spi_trans_byte_bw_new(Hi(Address));
    Local_8 = spi_trans_byte_bw_new(Lo(Address));
    Local_8 = spi_trans_byte_bw_new(Data);
    spi_eeprom_deselect_new();
    // wait for completion of previous write operation
    while(FM33256readStatus().Bits.WIP);  // it fails here
    spi_eeprom_deselect_new();
}

// read a byte from address (16 bit)
unsigned char FM33256read8(unsigned int Address)
{
    unsigned char Local_8;
    spi_eeprom_select_new();
    Local_8 = spi_trans_byte_bw_new(EEPROM_CMD_READ);
    Local_8 = spi_trans_byte_bw_new(Hi(Address));
    Local_8 = spi_trans_byte_bw_new(Lo(Address));
    Local_8 = spi_trans_byte_bw_new(0);
    spi_eeprom_deselect_new();
    return Local_8;
}

here is how I use it

unsigned char data = FM33256read8(15);
FM33256write8(10,15);


texts: How can I tell a n channel MOS varactor from a p channel MOS varactor using the CV plot (gate-source capacitance on gate source voltage)?

texts:
I couldn't find the differences of the 2 types of varactors (varicaps). I used the CV method and got the curve, but I don't know if I have a n type or p type. How can you tell?

How do you calculate the capacitance curve with CV voltages?


texts: NE555 Circuit stops working after random time

texts:
i finished my NE555 circuit and created some pcbs. After a few attempts i could get the circuit working, and tested it successfully.
I placed my circuit between a 12V 1.5Hz square wave signal and a 12V LED strip.
Everything worked fine, the circuit delayed the on-time of my led by a few hundred milliseconds.
Then I went for a week on vacation and when i came to test my circuit a second time, and nothing worked... (The circuit was laying on my desk and no one was at home)
The output voltage was not delayed any more and the output voltage was synchronous to the input voltage.

Luckily, i had ordered 10 pcbs and had parts to solder a few more...
I did so, and tested my circuit with my lab bench power supply and measured every pin/trace with my oscilloscope. Everything was fine and with my R1 potentiometer I could change the delay time of the output signal.

I decided to connect the new circuit between the +12V square wave and my led strip and now nothing worked any more!?
But in difference to the first pcb, the output voltage of this one stays at 0 volt for the whole time.
Back on my lab bench power supply and my oscilloscope i could reproduce this problem. The circuit did not work any more.

The strange thing now is, that the capacitors voltage changes if i change the resistance of the potentiometer. If i set R1 to 0Ohm, the Capacitor i charged up to 12V.
If i set R1 to 5k Ohm, the capacitor only charges up to something like 8V!?
The higher I set R1, the lower gets the Capacitor voltage?
If is test the same combination of capacitor and potentiometer on my breadboard, everything works just fine and the capacitor gets charged up to 12v every time, just the the charging time varies when i set the resistance higher or lower (How it should be).

Maybe someone can tell me what is going on and what i did wrong? I am really freaking out because even with my oscilloscope i can't find the root of the problem.

Thanks!!

I attached my scheme and my pcb design ;)


texts: How to store array of values in EEPROM of ATmega16 and then read it in sequence

texts:
I have this program in which I can store a single value in EEPROM. Can I store an array of values in EEPROM? How?

    #include <avr/io.h>
    #include <avr/eeprom.h>

    // macro for easier usage
    #define read_eeprom_word(address) eeprom_read_word ((const uint16_t*)address)
    #define write_eeprom_word(address,value) eeprom_write_word ((uint16_t*)address,(uint16_t)value)

    //declare an eeprom variable
    unsigned int EEMEM   my_eeprom_word;

    int main(void)
   {

    write_eeprom_word(&my_eeprom_word,OCR1A);       // store value in eeprom

    OCR1A = read_eeprom_word(&my_eeprom_word);     // restore from eeprom

    while(1)
    {

    }
    }


texts: Flat band voltage due to arbitrary charge distribution in the Oxide of a MOS

texts:
I am trying to calculate the flat band voltage due to arbitrary charge distribution in the oxide. but the actual result is somewhat different as you can see in the equation 6.3.5 of this link. what is the mistake am I doing can anyone help?
https://ecee.colorado.edu/~bart/book/book/chapter6/ch6_3.htm#:~:text=The%20proportionality%20constant%20between%20the,be%20the%20gate%20oxide%20capacitance.&text=Charge%20density%20due%20to%20electrons,layer%20of%20an%20MOS%20capacitor.


texts: Need transistor circuit to supply pulse/gnd signals to optical switch

texts:
I am a digital designer so anything analog is out of my expertise. I need to control an optical 2x2 switch with the following truth table:

The pulse is in the msec range and the driver current is about 200mA.
Link to data sheet shown below:
https://agiltron.com/PDFs/CL%202x2%202-Stage%20Series%20Switch.pdf
I have an FPGA that can control the transistors but not sure how to arrange them?
Any ideas?
Thanks!


texts: What are the operational differences between a battery and a plug-in voltage supply?

texts: I have a neat little circuit with which I am powering an electromagnet. Below is the schematic for the PCB I created. The positive lead of the electromagnet is connected to 12vdc and the negative lead of the electromagnet is connected to the MAGNET GROUND on the schematic (which is connected to real GND via the Darlington Transistor). The issue I have run into is that when I use a 12vdc plug-in voltage supply, the circuit works perfectly. However, when using a 12v battery (200Ah so the 300mA the magnet draws is not an issue) the output pulses, creating a high pitched whine from the electromagnet. I have determined the source of the pulse to be the 220 uF capacitor as the circuit does not whine when it is removed, but I am unsure why there is a difference between the plug-in supply and the battery.


texts:
I need to perform circuit simulations and from what I have been able to see the programs that are most used for this practice are Proteus and Multisim.
But such programs are not open source.
I have found several open source programs but to perform PCBs, they do not incorporate the circuit simulation option.

Are there open source circuit simulation programs similar to Proteus or Multisim?


texts: How do you calculate the required gain for an electret microphone amplifier?

texts:
Given that for example I have a -38dB mic such as this one, how can you calculate the gain needed to match the range of the ADC(5v)?

I found this page explaining some basics, and some other questions on this site that give some ballpark numbers but not much background.

From my understanding -38dB=10-38÷20=0.0125V/Pa, which agrees with this calculator.

Now I looked up in some table that normal speech is about 60dB SPL, which  would be 1060÷20×0.00002=0.02Pa which corresponds with another calculator.

This would mean a sound of 60dB SPL gives a voltage of 0.0125×0.02=25mV which means you'd need a gain of 4000 to gain even 1V (amplitude, rms, p-p?) and up to 20000 for 5V.

Designs I've googled had gains ranging from 40-1000, with a 200 gain breakout sitting on my desk. Sparkfun sells a board with a gain of 60, while the one by Adafruit goes from 25 to 125. This seem far cry from the 20000 I need according to my calculations to reach a range of 5V. Did I mess up my math somewhere, picked the wrong microphone, or is that just how much I need?


texts: Understanding a switched-mode power supply datasheet

texts:
I'm trying to make an AC/DC converter (230V AC to 5V DC). As part of this converter, for the first stage, I've decided to use a switched-mode power supply like https://www.digikey.com/product-detail/en/wurth-electronics-midcom/7508170312/1297-1174-1-ND/5700118

If you take a look to the datasheet, you'll see this:

As I understand, I can apply any AC voltage from 78V to 375V, and I will get two fixed outputs: 15V (DC) and 16V (DC).

Is that right?


texts: Why is air pump making high pitch when it is overloaded?

texts:
Coming back from a nice camping trip, I noticed all air pumps made higher and higher pitch when the air bed were about to be fully inflated. It is heard like the the motor is speeding up when it is overloaded. I opened the pump but it seems very simple - electricity from the batteries are directly feed into a motor through a switch. However, my understanding about a electronic motor is that the speed should decrease when load increases. Is there anything I missed?

10/4/2012 Update

Finally, I made my poor man's power supply by a computer PSU and went through a test. Driven by 3.3V, the air pump draws 4.5A when it runs with a free airway; when the output nozzle is blocked, the current drops to 3.3A. The test supports Dave's answer and I agree that this question is more related to physics.

The picture is the test setup.


texts: Please help me identify this connector type

texts:
Can anyone help me identify this connector types? I have tried finding this connector online and the closest one seems to be tamiya connector. But the ones I found being sold online has different locking mechanism.

This is the female counter parts:

It's used for a washing machine coin sensor.


texts:
Hello i have issue how i locate the variables on karnaugh maps.I know what to do but i have the problem how i locate it.What i mean by that as you can see i have this:

  F=A'B'C'+B'CD'+A'BCD'+AB'C' this
  is
   F=B'D'B'C'+A'CD'

what i want to understand because i can't and why happens this is.
I know how work the Karnaugh but i cant have the ABC in first line?or A'B'C' or B'CD what i wrote..And how much lines for this specific exercise?I have 4 so i think i will do 4.What i think is ABC',AB'C',A'BCD',thats how the lines will be my thought


texts: Molex 5039600695: What is the SIM card stopper referring to?

texts:
On some SIM card holder datasheets, I've seen references to a card stopper feature that prevents users from inserting a SIM card incorrectly. This card stopper appears to be a mechanical feature built into the body of the SIM card holder itself. Example on page 4:

The detail drawing for Molex 5039600695 also refers to a card stopper. However, this particular datasheet indicates that the card stopper is 1.4mm away from the body of the SIM card holder. I am not sure how to interpret this recommended card stopper position. I understand the idea of a card stopper as a mechanical feature of the SIM holder, but not in this context of something separated from the SIM holder.

In this case, is the card stopper a distinct component from the 5039600695 SIM card holder that would need to be purchased separately?


texts: What test can I do to determine a malfunctioning E bike motor?

texts:
It's gonna take a while to get a replacement controller module from China so I thought I could do some tests to determine what is not functioning properly.

Info: 3 phase brushless motor, 36volt rated controller, cutoff 30volts.

It's a typical set up, 3 wires to power the motor, 3 wires to get hall effect sensor state, 2 additional wires to power the hall effect transistors.

The problem: Suddenly the motor lost power and makes a loud noise suddenly. Then within a few seconds power dies as if the controller is preventing a short or something. You have to kill the throttle and hit it again for it to turn the motor again until it dies again.

I was told that disconnecting the hall sensors would still allow the motor to run, at a stand still without the sensors connected when I hit the throttle it creates a magnetic lock the wheel is frozen in place.

Opening the motor and inspecting everything mechanically speaking seems sound.
Power drain is minimal from the li-ion battery dips only 3 volts under full load to the motor. The failure is predictable there is nothing random like a short so I can reproduce the tests as needed. Maybe it is just a blown capacitor, maybe a blown hall sensor. If I can pin point it by testing then I can perhaps repair the sensors or its module.

What tests can I make to narrow the problem to find out what has failed exactly?

I have a multimeter but no scope.


texts: What is the use of SENSE + and - in a PSU?

texts:
I was in search of a good power supply for my radio. Apart from the batteries I have tried all the AC wall adapter or the SMPS based supplies seem to introduce noise in the radio. The SMPS being the worst.

I have an old PSU as in below pic unused in my collection. As per the data sheet its a high quality voltage source which made me think of using it for this purpose.

It has pins A,1,2,3,4,5,6,7 which corresponds to Adjust, - Sense, B-, +Sense, B+, Not Used, AC, AC. AC is rated for 115V. Its max current is 150mA, which is well within my current draw.

What is the use of the _ and + SENSE pins? I've seen this on an old PSU unit I had with me back from the 1960s. Will it improve my output in any manner?

Datasheet here.

Update: So, I unpacked the PSU today and did some adjustment and checking now.I connected the (-SENSE & -B) and (+SENSE & +B) together and adjusted the voltage to 8.8V. Now, I tried removing the SENSE lines from both +B and -B terminals and measured the voltages across the each terminals:
-SENSE & -B: 13.6V,
+SENSE & +B: 8.1V,
+B & -B: 22.4V,
-SENSE & +SENSE: 0V .
So, as our members have explained the sense lines seem to be very important in this case.


texts: Can an electrolytic capacitor withstand 0.1 V reverse polarity?

texts:
Let’s start the question with a brief description of my application.
I am trying to attach a headphone jack with a detect pin to a RDA5807 IC based FM radio project. I am using a separate microcontroller (ATmega8) to detect the insertion of headphone jack into the socket.
After a lot of searching, I came across this implementation which will work for me:

When the headphone is not plugged in, the detect pin (pin 4 of the socket) is connected to ground via pin 2 to the 2.2 kΩ pull-down resistor. When the headphone is plugged in, pin 2 is separated from pin 4 and is pulled up by the 100 kΩ resistor which is detected by the microcontroller.
Now, the problem is, the FM IC is controlled via I²C and can be put in a powered down mode (which will be the case most of the time.) While in power down mode, the audio outputs are grounded internally. So, while measuring the coupling capacitors in this state, I am reading about 0.1 V of reverse voltage across its pins, due to the 100 kΩ pull-up resistor (shown in the picture).
Will this cause the capacitor to significantly degrade over time or even pop?
I am using these capacitors and the only information I have about them is what they look like:

NOTES:

Yes, I understand that the 2.2kΩ pull-down resistor will waste some output power, but I'm fine with it.
Some implementations I saw actually made use of the headphone resistance of 16 ohm or so to detect insertion. That won't work for me, because I might insert an aux cable and connect it with another amplifier too, which will likely have a much higher input impedance.
The only type of headphone jack that I can get hold of is the type shown in the picture. I know that there exists jacks with the detection mechanism on the sleeve pin, and truly that would make life a lot easier for me, but they are super rare and I can't get any.


texts: How do I implement a feedback to keep the DC gain at zero for this conceptual passive filter?

texts:
Regarding an example passive LC ladder filter, when I sweep the source resistance, Rs, the filter characteristics changes as follows as expected:

On the other hand, if I sweep the load resistance, Rload, it seems the characteristics does not change, but the DC gain changes as follows:

For ease, I showed the above plots in linear Bode plot instead of dB. So 1 V corresponds to 0 dB.

I'm not trying to build a filter so this is just out of curiosity.

The Rload resistance forms a resistive divider and causes attenuation. If Rload was known to be 1 ohm then I could add a gain stage with a gain of two and compensate for the attenuation. But if Rload is not known and there is no buffer, can there be a feedback between the input and the output which would prevent any DC gain attenuation?

In other words such a feedback which would set the DC gain to zero regardless/varying of Rload so that the frequency response will start from 0 dB at DC. How could that be realized with any behavioral elements (like VCVS) or op-amps in LTspice or any other simulator?

I have written at the beginning of the question that sweeping Rload does not change the filter characteristics (besides DC gain), but am I actually wrong? Because I noticed that the phase and group delay plots vary with Rload, and below is the group delay for different values of Rload:

I thought the load resistance has no effect on any filter characteristics besides DC gain. Could you also expound on this?

Buffering solved both the DC gain, phase and group delay's dependence to Rload:


texts: Switching 2 momentary outputs sequentially with one momentary input... how?

texts:
so I have two buttons I need to trigger momentarily with a relay for each, the triggering needs to be done with a foot pedal that has a NO and a NC state
with each press of the pedal it needs to activate alternately one of the two outputs momentarily
the power already available is 24v


texts:
I am currently salvaging parts from a husqvarna automower 305 to use in later projects. Among the parts is a variation of this battery: https://www.amazon.de/Green-Werkzeug-Husqvarna-Automower-McCulloch/dp/B07HY1T4WL

It has 4 Pins, + and -, a T-Pin which I suppose gives me a tempereature reading, and then there is a pin simply labelled R. I have no idea what this one's supposed to be. Does anyone have any idea what this pin is used for? I got nothing.

Edit/Update: In the "adapter" used to connect the battery to the robot, the pin is designated "h". Maybe that can help identify it.


texts: Why does the 802.11 wifi spec allow for 11 channels?

texts:
The general wisdom is that it is better to only ever use channels 1, 6, and 11 as they are the only three non-overlapping channels for 2.4ghz wifi (in the US), and two adjacent networks on the same channel would perform better than two adjacent networks on different (but overlapping) channels.

So then, why would the IEEE even allow for 11 channels in the specification? Is there any possible use case where it would be desirable to use one of the in-between channels? Even if you were completely isolated from other networks, it wouldn't make sense to use other channels because you would then be limited to only two, rather than three non overlapping channels/access points.

I have read many articles explaining why its better to stick with 1, 6, and 11, but I have yet to come across any explanation for why they didn't just make three channels to begin with (1, 2 and 3 mapping to 1, 6, and 11 respectively).


texts: Convert a PWM to analogue with double the voltage range?

texts:
I have a PWM output (0-5v) that I need to convert to an analogue voltage. Simple = RC filter. However, the voltage range from that analogue voltage needs to be twice that of the input voltage, and I'm just not sure of the best approach.

Basically: 5v PWM to 10v analogue

A colleague suggested to use a voltage doubler (such as 7660) to power an op-amp, configured with a gain of 2.

Any other suggestions would be greatly appreciated.

Thanks


texts:
Possible Duplicate:
  Maximum attainable delay with Micro controller

I need to generate delays for one hour, two hours, etc. What is the maximum possible delay that can be generated in the STM32F207 controller?

Also, what is the procedure for the implementation using any of the timers available in the STM32F207 controller?


texts: How to check (with DIY methods) if an Inverter returns a Square or a Sine Wave?

texts:
I do not have an Oscilloscope, but I want to check if my 12V DC to 230V AC inverter does produce a sine or a square wave. Any way to verify that?

I know how a sine wave and a square wave sound, so converting this to audio might be a possibility? Maybe with a transformer? Just some input ideas.


texts: Why is noise is considered to be a "Common Mode Signal"?

texts: I learnt that the magnetic interference due to the Earth causes noise in the cable but I wonder why this is considered to be a 'Common Mode Signal' and why differential amplifiers are used to eliminate it?


texts: Comparing heating soldering with high current cold heat soldering

texts: which is more harmful to electronic components, mainly semiconductor ones, heat of heating solder iron or substantially high current of cold heat soldering (basically just miniature arc welding)


texts:
I am doing an experiment on Monostable Multivibrator using IC 555. But, I need to generate a trigger source (which goes into pin 2). I have a 5V supply and IC 555 timer.

I have used R1 as 100K and C1 as 0.1ufd.

The yellow line is the output from pin 3 and the blue line is the trigger input.

Another image:

So, basically, I am obtaining a reverse of the trigger input as the output. Why is this? What needs to be done to obtain the correct output of the monostable multivibrator?


texts:
I am trying to build this code on MicroC using Pic16f877. It is a code using Kp and Ki values to control a motor. But when building, i keep getting the error main function is not defined.
Below is the code:

#ifdef PID_H
#define PID_H

#define epsilon 0.01 //time elapsed before the next loop
#define Max 5
#define Min -5       //for saturation

#define dt 0.01
#define kp 20.0
#define ki 1.0
#define kd 0
void main(float output){
float PIcal(float setpoint, float actual_voltage);
{
  float pre_error = 0.0;
  float integral = 0.0;
  float error;
  float output;
  float actual_voltage;
  float setpoint = 5.0;
  TRISA.F0 = 1; //Configure 1st bit of PORTD as input
  setpoint = TRISA.F0; //setpoint is the input
  TRISA.F1 = 1;
  TRISB.F0 = 0; //Makes PORTB0 or RB0 Output Pin(forward motion of the motor)
 TRISB.F1 = 0; //Makes PORTB1 or RB0 Output Pin(reverse motion of the motor)
 {
//calculate P,I
  error = setpoint - actual_voltage;

//if error is greater than the epsilon
  if(error > epsilon)
  {
   integral = integral + error*dt;
  }
   output = kp*error + ki*integral;

 //saturation filter
  if(output > Max)
  {
   output = Max;
   }
  else if (output < Min)
  {
   output = Min;
  }

  if (output > 0)
  {
   TRISB.F0 = 1; //forward rotation of the motor
   }
   if (output < 0)
   {
    TRISB.F1 = 1; //reverse rotation of the motor
    }

   }
}
#endif


texts: How do I switch a PIN diode using a TTL control signal?

texts:
I'm designing a transmit/receive switch for an antenna using a PIN diode.
The PIN diode I'm using is UM7512 make: Microsemi.
I need to switch between -400V (off) to +5V (on). The switching time should be 50usec.
On current  is 200mA.
Off current is 1-2 mA.
I need a reference circuit idea or design about this requirement.
How do I approach this design?


texts: Transistor as switch with solar panel charging

texts:
I'm designing a circuit that charges a battery with solar power. Im using the TP4056 for this.
My question is the following. I want to use a transistor as switch to cut off the power if the battery is fully charged. (to prevent overcharge). And to drain the battery. (for demo purposes)
The transistor is controlled by an arduino pin.
I have the following schematic:

The solar panel is 5.5V and 170mAh.

Am I correct that there is no current flowing between the panel and the charger ?
How do I determine what the exact transistor should be if I want to interrupt the circuit. (5.5V before transistor, 5.5V after transistor) ?
Is this even necessary. Does the TP4065 automatically shuts off ?

Many Thanks in advance !


texts: Need help understanding how motors, sensors and other components of a prototype design factor into certifications for industry sale

texts:
I have built a prototype and I now need to create a production prototype that I can use as my template for a small 10-15 product unit batch order. I am in the United States where I plan to market first (UL and FCC certs).
My primary point of confusion is around the integration of a 269oz-in NEMA 23 class motor in a production design. My prototype currently integrates an Arduino, a TB6560 motor drive, OLED display, and HC-06 BlueTooth device (w/button press) along with this motor. What I really need help understanding are the following:

Custom PCB design or off-the-shelf PLC? What warrants using a PLC? I do not know if it is a viable option considering the other electrical components and functions that are required.

If I should design a custom PCB, how do I determine what needs to be re-designed into the board?

How do know if my OLED display, HC-06 BlueTooth, or any other selected components jeopardizes obtaining end-product certifications?

I get the feeling that using components like HC-06, which requires 4 quick pin-to-pin wire or solder connections out of the box, seems too good to be true. I greatly appreciate any additional insight into this.


texts: Sense resistors in system-side Li-Ion charger/gauge circuit

texts:
I'm working on designing a charger and fuel gauge circuit for a premade 3S3P Li-Ion battery pack. The battery pack has basic protection circuits onborad (over/undervoltage and a PTC) and only the pack positive and negative leads are exposed to the outside. I'm planning on using a TI BQ24735 for the charger and a Maxim MAX17205 for the fuel gauge based on clear documentation showing connection to a pack without using the balance inputs.

Battery charger circuit:

Fuel gauge circuit:

I'm confused as to how the current sense resistors in these two circuits are going to interact. The charger current sense (RSR in the first circuit) is on the high side and then the fuel gauge RSENSE is on the low side. Both circuits measure voltage across their respective resistor so I'm not too worried about having to account for the values of both resistors in a given circuit. What I don't quite understand how a low-side current sense in the fuel gauge is going to understand that the charger is doing its thing in this configuration. Is that actually going to work, or do I need to go a different route with this?

Also, what do I need for the protection circuit mentioned in the fuel gauge schematic given what's already in the battery? I'm assuming just reverse polarity protection.


texts: How do switches respond when more than 10 dial pulses are sent?

texts:
Forgive me if this is off topic but this is actually about circuitry design:

My understanding is that electromechanical Strowger SxS switches have 10 "steps". What would happen if 11 pulses were dialed, either from a phone that happened to have 11 holes in the dial and could send 11 pulses or by tapping and depressing the switchhook/hookswitch rapidly 11 times in succession?

Similarly, what about 12, 13, etc. pulses in succession?

I'm not sure if 11 pulses would dial 10+1 or simply 10 and then stop listening.

I've tried and failed to test this out, even though I have 2 PBX systems at home. I can dial the lower five digits easily using the switchhook but I fail more than half the time simply dialing 0 using the switchhook. And because the PBXs are electronic, they may automatically recognize 11 as invalid and default to a reorder signal.

If there is a difference between how electromechanical switches and electronic switches would respond, please contrast them. (I don't know how many people just have a SxS switch at home to test with though...)


texts:
I have a battery (3v coin cell) powered device with a digital input to a microcontroller. There is a pull down on the input of 10k.

It is connected to a switch outdoors which, when off, could have a resistance of 5k when its raining. The 5k resistance is enough for the microcontroller to think the switch is on.

How can I reduce the sensitivity of the input without reducing the pull down resistor. I could make it 1k but then if it rains it would mean it always pulls 0.5 mA which depletes the battery in about 2 weeks. Is there a way to make the input less sensitive without reducing the pulldown resistor?


texts: Lets say I want to test out a sine wave 120V 15Amp inverter by drawing 15 amps of resistive load. How can I draw this without generating very much heat, and optimized for as small as possible.


texts: sensitivity of ultrasound transducer related to output

texts: Can any one explain to me how is the sensitivity of an uktrasound head related to the Output pressure Level?


texts:
I got a few 2SD1048's, as I wanted to add a switch to an LCD project I have, so that I could turn the LCD screen on and off via a microcontroller pin.
The LCD screen is this and pulls ~100mA (rounded up).  I'm operating it at 3.3v and the 2SD1048's were selected for their very low Vce(sat), since I can't afford to drop much voltage across the switch into the screen.  I'm still pretty new to reading transistor datasheets, but it looks like the Vce(sat) for the 2SD1048 is 80mV at max, so probably 3.22V should reach the LCD screen.  Marginal, but it should power on and work.
However, what I'm seeing is instead 3.3V at the collector, but 2.60V at the emitter, which isn't enough to power the LCD enough to function.
What am I doing wrong here, or what am I misinterpreting in the datasheet?  Here is my circuit, voltages measured at Vin and Vout.


texts: why the wire didn't remain negatively charged when we disconnect them from current conducting wire?

texts:
Suppose when we connect one wire with current conducting wire then it also becomes negatively charge which has potential to accept electrons. But when we break the circuit, the wire becomes neutral again and doesn't have potential to conduct current.
How at one time it is negatively charge but when we break the circuit then suddenly it becomes neutral ?


texts:
I'm trying to build the classic-ish radiant energy receiver (as depicted in the picture). I've searched extensively, but everyone just seems to make the circuit with random C values and wire antenna.

My question is...since the circuit picks up wifi, radio,...waves, wouldn't it make sense for it to be in some sort of resonance? I'm pretty sure the C and L values (for the antenna) should be exact if we wanted to draw power from let's say the closest radio station.

Does anyone know how to calculate these values and construct the antenna winding (or should it just be a straight wire pointing up?)


texts: DMA on Cortex M4 for continuous UART transfer

texts:
I've never used a DMA before and I'm reading the datasheet for the Atmel SAM 4E
This question does not necessarily have to pertain to this device, it can apply to any device that supports DMA if they all essentially work the same.

But how much data can I transfer ?

If the transmitter and the receiver have a 4 deep FIFO, then I can transmit 4 bytes safely, without having to worry too much about lost data. I'd then have to wait until I can get some indication that the fifo is clear and ready to accept more data.

This then brings me to using flow controlled UART.

If I setup both transmit side and receive side to support flow control, then will the transmitter pause transmitting, when it sees that CTS is not set from the receiver and resume when the CTS is set?

If this is true, then I would assume then its possible to send as much data as I want without having to directly read the UART receive registers and send as much data as I want.


texts:
I am studying chapter 4 of Dorf title Modern Control systems(11 edition)

I am trying to use MATLAB or Labview to implement block diagram for open loop control systems for speed control of an armature controlled DC motor

I have also attached the figure of book

I understand that the rightmost block \$\frac{1}{js+b}\$ will be in feedback with \$K_b\$ block.
But what will be the relation of feedback block \$K_b\$ with the two left most blocks (\$1/R_a\$ and \$K_m\$ in series) ?? Independent individual feedback relation with the two left most blocks (\$1/R_a\$ and \$K_m\$ in series)  or the series combination of rightmost block \$\frac{1}{js+b}\$ and \$K_b\$ will be in feedback with the two left most blocks (\$1/R_a\$ and \$K_m\$ in series)


texts: I am currently doing layouts in CMOS VLSI Design and I have gotten to drawing stick diagrams. The schematic of the 2 input NAND gate is shown below. In drawing the layouts I have trouble deciding between the Source (S) and the drain (D) terminals of the MOSFET. I wanted to ask if these terminals are interchangeable or not. If they are, then are the two layouts shown below functionally identical?


texts: Saving Node Voltage For Different Circuit

texts:
I have 2  circuits. The resistance and capacities of the 2. circuit are voltage dependent/controlled from some nodes of the first one, eg. Rcircuit2= 10*V(C1V1); Q= 50E-10*V(C1V1).

I am using LTspice for the simulation.

Now I want to simulate only the first circuit and later the second one (I know you can have/simulate multiple circuits simultaneously, I want to have 2 separate simulations).

How do I store / save the voltages from the first circuit and import them to the second one?

As far as I understood .wave can only store +1/-1 V, which isn't enough.


texts: Detection of two different frequencies using oscilloscope

texts:
My signal has two different frequencies: 660kHz and 80 MHz.

How can I make the oscilloscope just display the 660kHZ frequency? Right now all I see is 80MHz.

Thank you


texts: Sensing state of an electrical appliance

texts:
I know nothing about electrical engineering however... Is there a way I can detect when an electrical appliance is on? For example when I turn on my tv, a small blue light turns on so I know, but say I have a device that doesn't show it is on, such as a printer, but there's no display. Is there something (a component) I could put that can sense when something is using power?
And where would the best place be to place such a device?


texts:
Had a few issues with a high side using darlingtons etc - what would be simplist
 3v3 logic driven hi side (12V output) driver (I'm thinming fet) that can handle 1-2A for running a solenoid, as a switch - frquncy is VERy low like on for 10 mins, off for 5 etc.
tia


texts:
What is an LTspice directive and how can you add it?
I am asked to set the simulation spice directive to a linear DC sweep between -10V and 10V with increments of 0.1V.


texts: Combo Indicator LED / Fuel Pump Relay Kill Switch

texts:
I'm looking to wire up simple on/on DPDT switch in my car so that in one position, power is cut to the fuel pump relay and power is sent to a fake alarm LED, and in the other position the fuel relay is enabled and the LED is disabled.

My plan is to connect the fuel pump wire to terminals 1 and 3 and the LED to terminals 4 and 6, but do I need to connect terminals 2 and 5 to anything for this to be safe/functional? For that matter, is it preferred to connect the loads and supplies to specific terminals or are they interchangeable?

Thanks in advance and sorry for my English.


texts: Do narrow-band single-chip bandpass filters for audio frequencies exist?

texts:
I am looking for a single-chip implementation of a bandpass filter for audio frequencies, but unsure if they even exist. All the filters I've seen seem to be at least in hundred KHz range. So my question is, do such filters exists?

An ideal filter would be something like:

A single-chip implementation with minimum extra elements added;
Reasonably priced (let's say under $10 a piece in bulk);
Narrow enough (+/-500 Hz is fine for my purposes)
Offer the binary output - i.e. when the input frequency is 0-350Hz or 450+Hz it outputs logical "0"; otherwise outputs logical "1".

The ultimate goal is to control a block of relays from the soundcard audio output by outputting a specific frequency.

Thank you for reading, and sorry if the question sounds lame - my EE degree is really dusted.

UPDATE: Thanks everyone for answering, but it only took an extra hour of thinking to understand that I can use DTMF. Extra five minutes to find about MT8870. Feeling really dumb now; you guys are awesome!


texts: How is power generation computed in a circuit?

texts: I have made a simple circuit of by attaching a 10 ohm resistor in series with an LED and then attaching it to the solar panel. I use an AVR Microcontroller to measure voltage across the resistor through ADCs and then measure the current flowing at that point in time. I do this at a frequency of every 1 second for now (though I could do it at higher frequency). So I were to calculate the power generated by the solar panel over some time, how would I go about it? How do you calculate power generation or consumption digitally through a circuit in very basic setup?


texts: Is probe compensation of a scope only for 10X setting?

texts:
I can understand that the idea of probe compensation is to make the sensed signal to be frequency independent as shown below 9C * R = R * 9C:

Does that mean that probe compensation should be done only in 10X setting? And what happens if the probe is only used at 1X setting? In that case we cannot rely on the waveform seen on scope as much ass in 10X case?


texts: Pulse width modulation and textual expression of resulting stimulus level

texts:
So we have been using pulse width modulation (PWM) as a means to digitally change the driving voltage of vibration motors. Usually, afaik, the resulting voltage from PWM is expressed as %duty cycle and not as a voltage (i.e., some % duty cycle, instead of Volts). We have used the expression %PWM in our manuscript.

Now one of the referees of our manuscript (indeed reviewer #2), is confused by this notation. Perhaps because they would like to call it % duty cycle (which is a valid argument). For technical reasons, I would like to replace the % notation entirely and call it voltage instead. So instead of saying 50%PWM (or 50% duty cycle), I'd like to simply say 2.5V (assuming the input was 5V).

Is it valid to use voltage as a unit (V) in scientific papers, while in fact PWM was used to emulate the voltage?


texts: Can TV antenna be used as Radio Antenna?

texts:
I tried the Coax Cable that is used for our television - make its copper core have contact to the antenna of my radio... but nothing happens, it doesn't improved the signal...

I also tried this, still nothing.


texts:
I am working on an NEC v850ES/JH3 controller for testing an SD card driver in SPI mode.
We interfaced the SD card slot directly to the v850ES/JH3 controller without any pull-up resistors. Does it have any negative effects?

I am able to initialize the SD card in SPI mode. I am also getting a 0x00 response for CMD16.
After SD card initialization I am changing the clock frequency to 4 MHz.
I am checking SD card busy or not (if the response is 0xFF then the SD card is not busy).
When I am sending a read command (CMD17) and dummy data, I get the response 0xC1, and after that, the next byte is 0x3F. That means the read command failed.
If we don't send dummy data after the read command then I am getting response 0x04,  meaning an illegal command. In this case also, read is failing.
If we won't check the SD card is busy or not then I am getting response 0x00 for the read command, which means the read command was accepted. And I am also getting the start token (0xFE), meaning the SD card will send a block of data. If I read 512 bytes of block data then I am getting all zeros. I am trying to read the boot record. That means some data is there other than zeros.
I am also facing the same issue with SD card block write.

What is the problem and how can I fix it?


texts: Need second set of eyes on 555 50% duty cycle soldered protoboard

texts:
I'm a hobbyist trying to learn the basics of the 555 timer, and am working off of the 50% duty cycle circuit from the National Semiconductor data sheet for the 555 (PDF pg. 10 Fig. 14) and have successfully prototyped the circuit on a breadboard, but am having difficulty identifying why my soldered protoboard version isn't working properly. Here's what I've looked at:

Schematic from the datasheet:

Below is how I've laid out the components and soldered them to the protoboard (as part of a larger design which is why explicit V_cc and GND are omitted):

(Bold lines are soldered connections, arrows are wire based connections. Red for V_cc, Black for ground, blue for intermediate connection and gold for primary output.)

Pins 1, 5 are connected to ground (I recognize that 5 should go to a capacitor to ground, but have omitted it here as it worked without it on the breadboard and space was limited)
Pins 2, 6 are connected together and their junction is placed between R_A  = 10 k Ohm and C = 100 uF.
Pin 3 is outbound.
Pin 4 and 8 are connected together and to R_A with a 5V regulated source.
Pin 7 is connected to R_B = 2.2 k\Ohm which is in turn placed between R_A and C.

I've gone through and taken voltage measurements and from ground

Pins 2 and 6 are 0.9V
Pin 3 is 0V
Pins 4, 8 are 5.01V
Pin 7 is 0.01V

My first thought was that I damaged something during the soldering process, so I went through and verified that the resistors and capacitor were functioning. The 555 sits in a socket, and each of the socket connections is going through.

So the big question is, what did I screw up in translating from the datasheet to this design? And, in general, what tests can I conduct myself to identify how to solve "why isn't my protoboard working" kind of problems in the future?


texts: HFSS - 50 Ohm Coaxial line terminated with 50 Ohm impedance boundary. |S11| too large

texts:
I'm modelling a 50 Ohm coaxial cable in HFSS that is excited with a waveport and terminated with a 50 Ohm impedance boundary.

The Z0 of the wave port is 50 Ohms (refined through tweaking dimensions of the teflon and pin size around standard SMA 50 Ohm cable designs).

The problem is that S11 mag in dB (at 4 GHz) is only -3.26 dB.. I'd expect that to be much lower given the 50 Ohm impedance boundary.

This result doesn't change when changing the following:

Changing the length of the cable (S11 mag doesn't change, but phase
does, as expected)
Changing port characteristic impedance - Zpi, Zpv,Zvi, Zwave
Changing PEC to copper Using curvilinear coordinates for curved
surfaces  Deembedding (same on and off)
Normalizing port to 50 Ohms (no change, as expected due to Z0 being very close to 50 already)
Mesh density (smallest tried is Lambda refinement of 0.25)
Doing a full 3D analysis (not utilizing symmetry)

I feel I'm missing something obvious..


texts: What effect does using two different forms of solder mask on the same PWB have?

texts: We found some PWBs that seem to have both film and liquid solder mask applied on the board. I have never encountered this before and was curious to see if this is acceptable for use.


texts: Reduce/Remove Sparks in AC and DC Contacts of Relays

texts: I see that there are sparks being generated whenever there is a connection established between two contact points in the relays. So is there a way to reduce/remove those spark generated in the relays.


texts:
I have a battery holder, 3 x 1.5V AA, connected to a resistor (100 Ohm or close), LED and Adafruit INA219 breakout board.
The bus voltage reading from the INA219 reports 1.0V. Where does this number come from?
The voltage measured at LED tips is 2
The voltage measured at the tips resistor is ~2.6V
Shouldn't the bus voltage be 4.5V?
The INA219 Breakout board Vcc and GND are connected to the ESP32 5V and GND respectively.
If I connect Vcc to the 3.3V the bus voltage shows 0.8.
(Removed the part related to Shunt Voltage since they are milli-Volts)

simulate this circuit – Schematic created using CircuitLab
  if (ina219.begin())
  {
    ina219.setCalibration_16V_400mA();
    Serial.printf("current (mA), Voltage (V): %f %f\n",
    ina219.getCurrent_mA(), ina219.getBusVoltage_V());
  }

output:
 current (mA), Voltage (V): 25.700001 1.012000


texts: Finding right component package in Multisim

texts:
I have started using Multisim.

I designed a 5V regulator and it works in simulation, now I want to export it to UtilBoard but I can not find the right package or footprint for my component as there are thousands of them in the database.

What I am looking for is common 1/4 Watt resistors, a pair of 100µF and 10µF electrolytic caps and one 0.1µF ceramic capacitor.

I only succeeded finding the right package for K317 regulator which happens to be TO220 package.

What is the best way and best place to look to find a package for the component. For example, how can I find the package type of a normal 1/4Watt resistor?


texts:
I don't really know electronics, so please excuse my lack of probably even basic knowledge
Ive modified a guitar, with SP3T/DP3T switches, which connect guitar pickups in different configurations (series/parallel/combinations/phases etc.).
i used Mini toggle switches.
everything is passive - no active electronics.
so, i have a new idea to make a 'computer' controlled version of the same thing (maybe with raspberry pi, or something, i did not think about the 'controlling' part yet).
but i need SP3T relays - and here i need help - there is so many types - most of them are industrial stuff, big bulky.
Can you recommend, or guide me to what type of relays i should be looking for? even proper naming for the stuff i'm looking for will help (googling SP3T relay does not help...)

i think that i need physical connection, not solid state (its just my guess) - i think that i want a good old mechanical connection here because the switches will be connected to a pickup, so sound quality is important, and i guess solid state may harm the quality...
i definitely need 3 positions - ON-OFF-ON
i think i want it to be latching (i don't want to keep applying voltage to keep the switch in ON position)
i believe it better to get some low voltage activated ones (idk - 5 volts or less?) i don't think battery powered controller (whatever it will be) will have enough oomph.

Thanks in advance!


texts: A question on transforming a non-inverting comparator to an inverting one?

texts:
Here is the schematics for the question:

I was using the LM311 as a non-inverting comparator without problem.

It works fine and here is the output below:

But if I use it as an inverting comparator, I get the following output below. As you see the output pulses have distorted tips. I circled one of them with orange color.

Is my transformation of the non-inverting comparator to an inverting comparator just by swapping inputs correct? How can I fix those non-flat corners?


texts: 12v DC rocker switch with LED, how to use in an AC application?

texts:
I have ten of these 20A 12V DC switches:

I'd like to install them in a 120V AC (typical U.S. home) application where their entire function would be to light their own built-in LED when switched on… so, no need for the switch to actually power on and off a device as they're intended.

How can I do this safely?

FWIW: this would be for a simple tally board for use in a kindergarten classroom.


texts: I am building an electrostatic seperator for plant material. the two materials I am trying to seperate have a negative charge but one responds a lot more to positve charges so I feel there will still be sufficient separation. I have the general plan for it done, I just had a few questions in regard to the rectifier, and if anybody had any input with the other aspects it would also be greatly apreciated. So now let me get into the plan. I attached a diagram to give you all an idea of what i am talking about. I plan on running a 220V cord to a junction box. From there i will have three connections, one to each motor and then one to the rectifier.Then from the rectifier it will run to the positive electrode. Attached to the motors will be the electrodes, the negative charge rotating clockwise and the positive rotating counter-clockwise. Each electrode is going to be made of aluminum. the negative having a diameter of 6 inches and the positive a diameter of 12 inches. Each also will have a depth of 12 inches. I feel this is the max size to go with still keeping a sufficient charge on the positive electrode. Then the negative will be grounded to the steel frame. So to my questions, I was thinking of using a 35A 400V bridge rectifier and was wondering if that would be the appropriate one. Also would it be fine to run just a positive from the junction box to the rectifier then the the electrode without a ground on that side? the only ground for the electrodes would be the one on the negative charge side. If i do need one between the rectifier and positive electrode, what would be the best way of placing it there? Also do you all feel aluminum would be the best material to use for the electrodes? Any help would be much appreciated.


texts:
I'm replicating an open source pcba in order to learn how to build more complex PCBs and there is a part that is not recommended for new designs:

https://www.mouser.com/ProductDetail/TDK/VLS252012ET-4R7M?qs=uxmvvYJjMIsaASiY9mND9w%3D%3D

What would be the best part to replace it with?


texts: MC34063 dc-dc inverting - capacitor question

texts:
For a project I try to build a dual supply for opamps in a device. I bought the MC34063 to invert the DC. The device should be portable, however, the standard schematic in the datasheet uses some very big capacitors.

The Question:
Can I use smaller capacitors?

I don't know what the function of the capacitors is. Should they store charge or act as some sort of cutoff resistor? The datasheet has some formula to make calculations, but those include the frequency parameter, even though its DC power. I will require less than 8V and 20 mA from the IC.

Best and thanks!


texts: How to tell polarity expected of a DC barrel jack?

texts:
I'm sure this information is somewhere around the internet, but I can't find it.

I have a device that takes a DC barrel jack. I don't know the polarity it expects though. There is a marking though. It looks like this:

___
---  12VDC

I'm 99% sure it's a symbol to indicate the polarity, but which is it? Positive inside or positive outside?


texts: What is the difference between 1-bit SDIO vs SPI?

texts: What exactly is the between 1-bit SDIO vs SPI? Does one have advantages/disadvantages over the other?


texts: Base voltage peaks at about 0.8 volts, why?

texts:
I'm learning about transistors so I build the circuit in the image below and plotted the voltage at Vc (collector) as a function of base voltage, marked VBE. The transistor was a 2N3904.  I had two power supplies, one supplying the 5v rail and a second that I could adjust from 0 volts upwards (they had a common ground). I noticed that I couldn't get the base voltage to go much above 0.8 volts. If I pushed up the supply voltage to 5 volts I could get the base voltage to about 0.85 volts. I am sure there is a simple explanation but why does the voltage at the base max out at about 0.8v no matter what voltage I apply?

I know that the transistor is saturated by the time I get to 0.8 volts.

Update: I've also now plotted the base voltage as a function of the applied voltage via the 1K resistor.

Having now read the comments and thought more about this, the explanation seems straight forward. We see from the second graph that at a VBE around 0.7 v the curve starts to flatten out, this is of course when the transistor starts to open up and in doing so the BE resistance drops thus holding the VBE voltage constant after that. As others have pointed out this can't go on forever but will eventually start to rise again once the resistance stops dropping.


texts: (Experiment) What if I run a DC motor with unfiltered sine pulse DC voltage?

texts:
I have read a lot about using high frequency square/rectangular wave pulsed DC for motor speed control aka PWM-ing, but my question is a bit different.
What if I run a DC motor with a low frequency unfiltered sine wave pulsed DC? Let's say that I want to run a 12V linear actuator motor from the low frequency 50/60Hz AC mains voltage, using a suitable step down transformer and rectifying diodes but no capacitors or any sort of filtering. My assumption is that full wave rectification should work better than half wave.
What are the possible outcomes regarding energy efficiency and longevity of the motor with this setup?


texts: Avoiding heavy controller boards in a MEMS sensor circuit

texts:
I am very new to the circuit designing and the "Internet of things" world. I am trying to put together, for simulation purposes, a system that can pull information from a mems accelerometer sensor and pass it on to a bluetooth module, which then sends it to a mobile device.

So normally the setup would be:

MEMS Accelerometer -> Controller Board (processing here) -> Bluetooth transmitter -> phone

My question is since the phone is already a device that is capable of far superior computing, is it possible to avoid the controller board, resulting in the following setup?

MEMS Accelerometer -> Bluetooth transmitter -> phone (processing here)

Again, I am very new to this field. I just need a setup that records 2D accelerations (voltage level in analog mems, duty cycles in digital mems?) in a car and sends it to a phone inside the car, which then does some processing to calculate actual acceleration and velocity calculations.


texts:
I am trying to use a relay to power a RPi for the first time and just confused by how I should wire it. I am trying to control the relay with a ATtiny10 MCU (microcontroller) if that helps in explaining setup. My power supply input and both MCUs are 5V. Any help/guidance would be greatly appreciated.

Part # on Mouser: 769-DS1E-SL-DC5V

I am thrown off by the 2 positive ends in the datasheet circuit diagram.


texts: Correct SPI, I2C termination and EMI limiter for external bus?

texts:
[EDIT]
This question has been edited. The bus does not split anymore. The entire question and figures has been edited.

BACKGROUND
I'm using an ATSAM3U2E and want to include both the SPI and I2C bus in the expansion connector for future expansion boards. Since I don't know how many devices will be connected to each bus I'm looking for a guideline in how to terminate the bus correctly on the main board (and backplanes?).

There are actually two backplanes.

simulate this circuit – Schematic created using CircuitLab

Both busses (I2C and SPI) are connected to the two backplanes with a ribbon cable. On each backplane there are 1 resp. 3 edge connectors where the expansion board/modules are slided in.

The cable distance to the x3 backplane is about maybe 20 - 30mm but signal traces on main board might be about 50mm. The x1 backplane cable is about 50 - 60mm.

I want to keep down the amount of traces and wires so I don't plan to pair them with GND in the cables.

Since I don't know what these modules and expansion board would look like in the future, I guess we have to estimate an average amount of devices. There is already one SPI device on the main board and estimate 1 SPI and one I2C on each module and Expansion board to a total of:

Expansion board bus - 1 SPI and one I2C devices.
Module bus - 3 SPI and 3 I2C devices.

I aim to run the busses at max speed; SPI @ 20MHz and I2C at 400kHz if possible.

The expansion board is supposed to add new high speed ports such as Ethernet or other more advance expansions. It will most likely have it's own MCU.

The modules are for more simple tasks, such as keypads, LED indicators and maybe a small LCD.

QUESTION
Since the SPI and I2C pass through 4 ribbon connectors, I assume I will put some serie resistors close to the MCU. But how about EMI in the cables? Should I put something at the connectors on the main board and backplanes as well? How about the edge connectors, should I place anything there?

The I2C pull-up resistors, should I put them close to the MCU or close to the I2C bus end on the backplane?. Or at the expansion connector?

If the busses was only on the mainboard, I would have it covered. But since there are so many connectors/cables on the way I'm not quite sure of how to deal with this correctly.

(For the sake of discussion, assume that I have the SPI SS signals covered, no need to point out that I don't mention them.)


texts:
Quick question (hopefully!). I'm new to electronics, but getting quite interested. Coming from a programming background, it's always interested me...

Anyway. I have a circuit with two DC Power sources, one is 12V the other is 7.2. I have a regulator which turns that down to 5V. Now, the 12V power source isn't always available. The 7.2V however, is always available. But I would like to build a circuit that will use the 12V if it's there, and 'fall back' to the 7.2 if it isn't.

Once I have this sussed, I need to have a look into re-charging the 7.2V battery from the 12V source when it's available, but that is a problem for another day!

It sounds simple, but I'm guessing it isn't? Please help. :)


texts: Question regarding components in Advanced Design System

texts:
I am trying to use ADS to create the scheme of an amplifier which includes the following elements

B1:

Description = 100 MHz Short Ferrite Bead, Surface Mount

Part Number = 2743019447

Manufacturer = Fair--Rite

C1:

Description = 5.6 pF Chip Capacitors

Part Number = ATC600B5R6BT500XT

Manufacturer = ATC

However, I am unable to find ferrite beads in the components library (should I use simple inductors instead?). Also, what is the importance/relevance of the part number and manufacturer? How should this information affect the components I select from the components library?
I'd appreciate some insight on this, please.


texts: How do I use this voltage regulator with a digital pinout?

texts:
I'm trying to learn about electronics, so please bear with me and keep in mind that my idea may be completely nonsensical...

I have this voltage regulator: T317CM

I want to regulate the voltage of a circuit using the digital pinout of a computer board, which is on a separate circuit. If the digital input is high, the voltage of the circuit should be reduced, and if the digital input is low the voltage should be unaffected. Or vice-versa, it doesn't matter. I want a setup something like this:

I can't make any sense of the datasheet, but with a few packs of cells and a multimeter I can reduce 7V to 2V, and keep at 7V if I short two of the pins. If I just make the diagram above the voltmeter always reads 7V, regardless of the pinout voltage. The pinout circuit only connects to the circuit being regulated with that wire - does the ground wire need to be connected somewhere too?

Here's a table of expected inputs/outputs:

V of Digital Pin  |  V in  |  V at voltmeter
       0V             7V            7V
       2V             7V            5V
       5V             7V            2V

These are just rough values and it can be the other way around if that makes the circuit simpler (eg, V at voltmeter = 7V when digital pin is 5V)


texts: Is it OK to place ground plane under transformer?

texts: I have a large transformer (50kHz, ferrite E-core) on the PCB. I want to pass power rails under it on the bottom layer. Should I place a large ground plane on the top layer to shield these power rails from the transformer? Is it a good idea? Would this ground plane increase leakage flux from the transformer core because of the Eddy currents on it?


texts: What is the pin configuration of an Hitachi HN46532-2 Mask ROM?

texts:
I'm working remotely with a person that has a Canon BX-1 computer from around 1978. He has the computer and I have fuzzy memory of the machine. There is no hardware documentation to be found, so we are reverse engineering it to get a dump of the MASK ROM card.

The six mask ROMS are Hitachi HN46532-2. We have found some information such as it has 12 address lines and 8 data lines for an 8 bit by 4K array. The package is a 28-pin DIP. Tracing the pins and looking at the power points it doesn't seem to match later chips of that size. These have 5V power on pin-14 and 0V on pin-1.

I haven't been able to find an Hitachi datasheet or components handbook that includes this chip or a 28-pin pattern that matches the power configuration.

The card:

The ROMs:


texts: Scaling amplifier, analog switch, fast response

texts:
simulate this circuit – Schematic created using CircuitLab

Hello everybody, I just try to design a scaling amplifier with different slopes and offsets. The problem is that the transient response became instable due to the capacitors of the analog switch. Do you have any idea to solve the problem?

Specifications design:

Input signal : Pulse with a frequency= 500kHz

In-out latency <= 100ns


texts: Can anybody recommend some literature or explain some rules of thumb for tapering planar waveguides? As I understand correct tapering is needed for example for bended waveguides or like in the picture below to increase magnetic ac field of the line in the tapered middle and avoid step discontinuities. Now I can put this geometry in something like HFSS, CST, Sonnet and optimize tapering to get best impedance match, less attentuation. So in general, is it better to make the tapering in steps like in the picture or why not go directly from large ground line width to the smallest one in the middle with only one tapering section, here it's two


texts: Bypass capacitors around DC-DC converters

texts:
DC-DC converter outputs with bypass capacitors

Thank you for any help! This is my first question post, so let me know how I can improve it.

I'm working on my first Altium project, which is to remove several DC-DC converters that were causing noise in our atomic force microscope system -- two of them are shown in the first schematic. Note that the red writing is how we modified these manufactured boards to fix the noise problems. Ironically, I think they were meant to isolate the rest of the system from noise caused by the motor drivers.

I am wondering which of these capacitors and diodes are unnecessary now that the dc-dc converters are being removed from the design. My guess is that the input capacitors are all unnecessary, they are to smooth the input voltage to the dc-dc buck converters. I think that the smaller capacitors at the output are also for smoothing the higher frequencies of ripple caused by the converters. But do I need to keep some of the capacitors between 24V/15V (was previously 12V)/GND? The situation has changed in that I am no longer stacking "floating" voltages to provide 24V, so maybe I can just get rid of all of them? And I must admit I'm not actually sure what the diodes are for.

For context, these two lines are being used to power a row of motor drivers, which are each configured to run at either 12 or 24V -- the second schematic shows one of them... they are all identical except for which 0 ohm resistor is populated.


texts: receiving transmissions transmitted on different channels sub-1 GHz using one receiver

texts:
I am using a RF development board along with a CC1120 RF modulator + CC1190 amplifier on carrier frequency 868MHz, RX filter bandwidth 25KHz, modulation format 2-FSK, 1.2Kbps bit rate, 10dBm output power, with all sync registers set to same on all receivers and transmitters. Despite the specific settings, my general question is below.

If a transmitter transmits on a channel a receiver is not yet tuned into, would the receiver be able to guess the transmission frequency at the time sensing the packet and still fully receive the packet? My problem is, If I do not know on which channel a transmitter transmits, what would be the fastest/easiest to receive a message from such a transmitter? I have about 100 nodes trying to communicate with each other and everyone is not tuned into the same carrier. How do I go about solving this issue?

thank you so much for your responses.


texts: Simple question, but I can't find anything on the internet about it. Why would Espressif not support NAND flash when it is the more economical option? I ask because I'm trying to integrate a 128MByte flash into a project to read audio files from. My BOM would be too expensive with NOR flash on it, so I'm trying to find a way to use NAND flash.


texts: mdot Analog in: how to connect Grove temperature sensor?

texts:
I am starting with multitech mdot product.

I am confused about how can I use the mdot pin PB_1 (linked to A0 in UDK) to read my Grove temperature sensor value.
Is it enough to simply connect it to the sensor signal output or should I configure the microprocessor ADC to be able to use the pin PB_1 as an analog Input?

in the developer guide page 21 the pin described as: PB_1/AD0/DIO0

what does this description mean?

Best regards.


texts: Deriving 2nd order passive low pass filter cutoff frequency

texts:
I'm working on a 2nd order passive low pass filter, consisting of two passive low pass filters chained together.

simulate this circuit – Schematic created using CircuitLab

Let \$ H(s) = H_1(s)H_2(s) \$ where \$ H_1(s) \$ and \$ H_2(s) \$ are the transfer functions for each separate filter stage.

Then \$ |H(s)| = |H_1(s)||H_2(s)| \$

Knowing the magnitude of a passive low pass filter,

$$|H(s)| = \dfrac1{\sqrt{ (\omega R_1C_1)^2 + 1} } \times \dfrac1{\sqrt{ (\omega R_2C_2)^2 + 1} } = \dfrac1{\sqrt{((\omega R_1C_1)^2 + 1)((\omega R_2C_2)^2 + 1)}} $$

Then trying to find the cutoff frequency:

$$
\left(\dfrac1{\sqrt{2}}\right)^2  = \dfrac1{\sqrt{((\omega R_1C_1)^2 + 1)((\omega R_2C_2)^2 + 1)}} $$ $$
2  = \sqrt{((\omega R_1C_1)^2 + 1)((\omega R_2C_2)^2 + 1)} $$ $$
4  = ((\omega R_1C_1)^2 + 1)((\omega R_2C_2)^2 + 1) $$ $$
4  = (\omega R_1C_1)^2(\omega R_2C_2)^2 + (\omega R_1C_1)^2 + (\omega R_2C_2)^2 + 1
$$

And I'm stuck. Research on the web tells me \$ \omega_c = \dfrac1{\sqrt{R_1C_1R_2C_2}} \$, but I can't find why? Can anybody show my the derivation to find this?


texts: High-Level Synthesis (HLS) vs RTL for ASIC flow

texts:
I'd like to know when it's a good idea to use HLS over RTL (Verilog/VHDL) design if I'm targetting ASIC implementation? Can synthesis tools like Design Compiler convert HLS C/C++ into gate-level netlist, or is there a specific HLS synthesis tool? and how efficient is ASIC flow for HLS compared to RTL in terms of clock freq., area, and power? Does HLS C/C++ development really save the design time compared to RTL ?

Thanks