texts: Is my thinking right for the simple harmonic circuit

texts:
If this is a simple harmonic circuit, then what is the \$X_C\$?

I know harmonic circuit means that there is no value in the imaginary part of the impendence or admittance, that is, \$Z_{th}=R+0j\$ or \$Y_{th}=G+0j\$.

In this question, if the circuit wants to be a harmonic circuit, I think \$\frac{1}{R_1+12j}=Y_1\$, and \$\frac{1}{-jX_C}=Y_2=\$, and \$Y_1+Y_2=\$real value, not complex value.

So \$Y_1+Y_2=\frac{1}{1+12j}+\frac{1}{-jX_C}=\frac{1-12j}{145}+\frac{j}{X_C}=\frac{(1-12j)X_C+145j}{145X_C},\$ so now our purpose is let \$-12X_Cj+145j=0\$,

that is \$12X_C=145\$,so \$X_C \approx 12Ω\$

The solution from the book

\$X_C=X_Lp=\frac{1^2+12^2}{12}=12Ω\$

Although our answer are the same, I still want to ask that is my thinking, right? Why can the book just calculate like that, it seems the author just use some unknown formula. Does anyone know about that formula?


texts: Identify large unmarked transistors for Volts / Amps?

texts:
I have some components, I believe they are transistors, that I got from a decommissioned electric train. They are rather large, but have no markings on them other than what is on the diode in the center position DSA 42-16A 436C which isn't pulling anything up for me.

Is there anything I can do to test it for it's load capacity? I was thinking of using it in a PWM for a 480V 200HP motor and wasn't sure how many I would need to run in parallel. This was located near the regenerative braking circuitry for what it is worth.


texts:
I have AD811 in my application that works just fine but as it is working in +/-15 v supply at around 14.5 mA, it's power is around one third of watts. It is hot when touched. I checked if this is a malfunction in this website and contacted Analog Devices Technical support and I am sure that this is a normal behavior of this device.

Now I am thinking about a cooling method for this device but as this DIP package has no where to attach a heat sink, I thought about some options like these ( regarding the device works in high frequency up to 50MHz):

Using a fan: fan's motor may impose some noise
Putting a flat heat sink on top of the device , attaching it with silicon paste and grounding it
Using a thermoelectric coolant element.

I have never heard about cooling methods for DIP packages especially in high frequencies, I want to know if there is any standard method for that.


texts: Electromagnetic radiation from spark gap

texts:
I am an electrical college student.
I learned from some papers, sites online, including this forum that lightning discharge or any electrical arc emits wideband radio frequency because the odd integer harmonics of a square wave and an electrical arc is similar to a square wave. (Correct me if I am wrong, please)
Today I tried to generate an impulse voltage with a multistage impulse generator.
Here is the picture  of the waveform from the oscilloscope:

White: impulse voltage without air breakdown.
Yellow: impulse voltage with air breakdown (electrical arc occurred on the sphere gap)

When I generate the impulse voltage with air breakdown, it creates an arc on the sphere gap. Can I get the frequency domain from this yellow wave with fourier transform? I do not really understand it yet, but since this is a non-periodic wave, can I get the frequency spectrum?
I want to know what exactly the electrical arc creates electromagnetic waves on a very wide frequency really means, and how.


texts: Die Temperature conversion result of the pipeline ADC

texts:
Could you help me with this question?
I have some difficulties to answer it.
The question is from the PIC24FJ128GC010 family datasheet and after some research I just know the meaning of the different values :

IRNG value means that the internal  currentsource must be set for 5.5 μA
PVCFG (Converter Voltage Reference Configuration for ADREF+ bits) is on VREF+
NVCFG0 (Converter Voltage Reference Configuration for ADREF- bit) is on AVSS

Maybe we should use this formula : Tdie = 710 mV – Vdiode / 1.8 (indicates on the datasheet)
But I don't know how to make the conversion result.


texts: Can a lighting transformer be used to power a pump?

texts:
I have a pump that draws 60W at 12V.

I had a little old linear hobby power supply I was using to power it in the garden but condensation killed it. Not a surprise but I needed the pump working more than I cared about the PSU.

I have a couple of waterproof lighting transformers in the garage and thought I'd see if one would run it.

It doesn't say on the label, but I'm guessing they're switch-mode (?) and the only two discussions I've found on the web re. SMPS and motors says they should work.

Anyway, when I tried it, it just sounds like its 'buzzing' the motor on and off very fast, which makes sense.

I don't know what to buy to power the pump. SMPS seems completely dominant save for linear bench PSUs. Maybe a lighting transformer doesn't work because of some other reason and that a different SMPS will work??

Thanks,

Luke


texts:
I am looking at an oscilloscope (LG 3040D) that is connected to the output a half-wave rectifier. The input of the half wave rectifier is a 20Vpp at 60Hz, a stepped down voltage from the wall.  I know that the signal that am I looking at is, at the output, only a DC signal - that's the whole point of a half-wave rectifier!

Since the oscilloscope has two modes (AC and DC) changing in between the modes, from what I understand, introduces a capacitor into the circuit which cuts out any constant DC voltage from the signal that is being viewed on the oscilloscope. But, since our signal is not a constant DC signal, it can still pass through the capacitor and is displayed on the screen even in AC mode.

Here comes the crux of my question: on this oscilloscope, there is a GRD feature which allows you to ground the circuit and use it as a point of reference. In DC mode, when you ground the circuit and then view the signal again, you see the signal on top or "above" the GRD reference. This makes sense to me, the half-wave rectifier is only taking the positive portion of the sine wave since the diode can only conduct in one direction, leading to only half of your input signal being "used".

But when you then put the oscilloscope into AC mode, ground the circuit and then observe the signal, it is not "above" the reference or entirely below, it is nearly centered on the signal. Why does this happen and how can it be explained? Does it matter where the signal is in AC mode? Is it supposed to be anywhere in particular with respect to the reference?

I understand this is a convoluted question that ultimately doesn't need to be discussed and comes from a lack of full understanding of how things work, but I am totally confused at the moment.

Attached is a crummy drawing in paint.

Thanks!

EDIT: I have an additional question:

As a follow up question: for a half-wave rectifier, what is the "AC" voltage and how do you measure it? Additionally, What is the DC voltage and how do you measure it?

From another answer, the DC voltage is the "offset" between the AC and DC signals when viewed in AC and then DC mode. How do I then measure AC signal? Go into AC mode and measure from the peak to GND?

If I do it that way, the those values are: VDC= 2.9V and VAC=6.0V (from reference to peak). Does that seem correct? Finally, is it incorrect to talk about the voltage in this way?


texts:
I have several power sources that are able to power the 3.3v rail in my circuit.  Only the U2 needs to ever be disabled. The problem however is when PWR1In is brought up slowly and the other two sources are off there is a point where U5 oscillates on and off. Looks like the input voltage is dropping which is tied to the enable pin. This turns the LDO off. Once the LDO goes off the input voltage comes back up and the LDO comes on again. etc. See the scope shot.

Green = Input to U5
Red = Output of U5
Blue = Input to U2

What is the standard way to setup a circuit like this so that it
A. takes power from multiple sources
B. does not cycle on and off for any input voltage range.

Note: If I change the micro startup voltage the oscillation point changes but it still has an oscillation range.
VConn is a 5V source, PWR2In is a 5V source, PWR1In is a 5V to 20V source.

I've added a second scope shot. In this one blue is still PWR1In, Red is still 3.3v rail, but green is the EN of U2. (still getting used to formatting on stackexchange)


texts: RMS Current through output diode in a flyback transformer with multiple outputs

texts:
I clearly do not understand where does this formula comes from ... (I did not find it on internet)
$$
\mathrm{
I_{diode_{rms}} = \frac{\sqrt{1+\frac{A²}{3}}}{\sqrt{1-D}}*I_{out_{avg}}
}
$$
where Iout is the output current drawn by the load, D is the duty cycle and A is defined as follow (it seems to be the transfer function of a flyback working in CCM but it is not exactly right) :
$$
\mathrm{
A = \frac{(DVin)^2}{2L_{primary}P_{in}F_{sw}}
}
$$
where Fsw is the switching frequency of the flyback, Lprimary is the primary inductance of the flyback, Pin is the input power.
If anybody is able to demonstrate this formula even for a simple transformer with only one output,  it would be nice !
Thank you very much and have a nice day !


texts: How to use 4 pin Honeywell NBP Series Pressure Sensor give 1 pin analog output?

texts:
I am trying to use HONEYWELL NBPDANN100PAUNV Pressure Sensor.

I found a example at Interfacing pressure sensor to arduino

As this example says as instrumentation amplifier based on quad opamp LM324 is used for conditioning the output voltage from the pressure sensor.

But I can't get any analog values from this circuit also I apply different Air pressure to sensor.

Help me to use this sensor in a circuit and get the Air Pressure values?


texts: Celestial Altium Library does not show symbols or footprints

texts:
I tried to install the Celestial Altium Library a few days ago. I was hoping for a large library of components that could allow me to quickly build some prototypes from time to time. This is in Altium 19.1.
What I got was a large library of part numbers (very promising), but I cannot see symbols or footprints. Where there should be symbols / footprints in the Components panel, I see "Symbol is not present" and Footprint is not present".  I don't claim to be an Altium superuser.
I've been searching for answers for a while and don't see many references to the Celestial Altium Library
I'm guessing (hoping?) that I simply did something wrong. Any ideas?


texts: Can a voltage regulator or stabilizer increase voltage and current simultaneously when used with a generator?

texts:
I have just built a generator with a stepper motor I found in a photocopier/printer (24VDC, 0.7A) and a transformer. Without load, the voltage is around 406 VAC. With a bulb (230 VAC, 18 W), the voltage drops to 240 VAC.

Can a voltage regulator or stabilizer be of any help in making this generator power a number of household equipments?


texts: Can anyone identify these PCB connectors?

texts:
I've got a board with 3 headers I'd like to connect to, but I can't identiy them to find suitable mating connectors, can anyone here help, or have suggestions for a reasonably secure alternative way to do it?

Is 13 mm x 6 mm (excluding the rails), I'd guess the pin spacing is around 4 mm, but I can't measure accurately enough - could be a little more or less.

16.5 mm x 7 mm (excluding the latching ramp). Pitch is ~ 5mm

18.5 x 6.3 mm (excluding the rails). Pitch is ~ 6.5mm

Thank you


texts: over using timer, calculating exact one second delay

texts:
Can you help me to write a macro which generates a one seconds delay by using Timer1 or Timer0 ? In other words, I have tried to write a macro for 1 seconds delay but I could not manage it .Why I am trying to write a macro is because I will use that macro in several place.

If you know more about timer, can you give me general formule when time is calculated ?

EDIT:

pic16f8xx
4MHZ
MPLAB simulation = 5 MHZ

EDIT:

"... [I] actually don't just want a delay, but using interrupts to execute a task later when 1 second has passed while doing other things in the meantime. .."


texts: Triode Regenerative Receiver Circuit - room for improvement and possible errors

texts:
I've designed this radio circuit, it's made to work on the 80m and maybe 40m band.

Regen is controlled using a pot in the tickler coil. Tube is ECF82, coil is air cored on a 30mm former. Will it be able to receive LSB and CW, or just AM? Can you recommend any good literature on the topic of regen receivers?


texts: Analog implementation of imaginary roots in a transfer function

texts:
I have a simple boost converter, and from multiple papers I've read through, a Type 3 Compensator is recommended. I designed one in Matlab/Simulink, and it reacts very quickly. The problem is, when I solve for the poles of the transfer function, there is the one at the origin and then two imaginary poles. According to TI report SLVA662 (on page 9) the equation for a Type 3 Compensator is

Obviously, the roots of this transfer function are always going to be real (unless there's a way to implement imaginary resistor or capacitor values I'm unaware of!)

I don't necessarily need a Type 3 if I can implement my other two-zero three-pole compensator system, but I'm a bit stuck on how to do this without digitizing the control loop.

Thanks!

Edit:

Ok, for more clarification, the transfer function of the compensator I designed is:

The poles are at 0 and - 1.6e5 +/- j9.2e4. The zeros are at -7.9e3 +/- j3.4e3.

I cannot get the numerator/denominator of this transfer function to match the numerator/denominator of H(s) above with real resistor and capacitor values.

So my overall question is: how do I implement two complex conjugate imaginary poles or zeros in a compensator transfer function with an analog circuit, if even possible?

Here's the comparison of the simulation results between my Type 3 compensator and the ADRC compensator I designed in Simulink. You can see it's far superior to the Type 3 compensator.


texts: Electric grid power transformer winding: If it is milliohms, why does 9V DMM show infinite ohms?

texts:
When testing large MVA power transformers, like 66kV to 16kV, the winding resistance in DC ohms is milliohms.
It takes a high current supply to do this, then the V is measured across the winding to determine the resistance using Ohm's Law.  If the resistance is less than 1 ohm, why does a 9V digital multimeter show infinite ohms?
I am guessing/assuming that there is a physics explanation.  My guess is that the electric field created in the conductor (winding) from a 9V battery is not enough to polarize the mass of electrons in the primary winding.
It also intrigues/confuses me that I can use a 9V DMM to measure other primary windings on smaller transformers with no problems.  How long is the coil of wire in a primary winding (approximately)?
So why does a 9V DMM yield infinity when the real primary winding resistance is in milliohms?


texts: Pros / Cons of LM35 and Thermistor, what alternatives?

texts:
I'm wondering which benefits/downsides I have using following thermometer?
Is there something I'm overseeing? For easy temperature measuring, what would be the easiest? My Opinion is LM35, am I right? When should I use which of them?

I don't have any experience with electrical engineering (so it might be that the question is very basic)

I would appreciate if you could suggest some Contra points for each thermometers

LM35

Pro

Easy to calculate: Temp = (Vout - 500) / 10
Accurate enough & cheap

Contra

nothing negative?

Thermistor

Pro

Accurate & cheap

Contra

Non linear; Have to use Steinhart-Hart-Equation to calculate the temperature

Alternatives

1-Wire

Pro
- Digital (is that a pro point?) so basically just reading the temperature

Contra
- compared to the others very expensive

Can you suggest me any other temperature sensors and tell me more downsides of the above listed ones?


texts: How does conversion to electricity work?

texts:
I'm having a bit of a hard time understanding how electricity is created in the practical sense. For example, when heat is explained , you have the scientific definition of what heat is , and then you have real world practical examples , (like rubbing your hands together , etc).

When it comes to electricity though , when I ask how it is made , I am always told basically 'this uses a generator which creates a conversion' , but how does that work? How is physical work converted into electricity? If I were to start off in nature and had to try to create it on my own , how would I do that?

To me it sounds like you take two magnets and get them to rub together fast enough to create the 'friction' which is electricity


texts:
I would like to learn to use an oscilloscope properly. I used them a few times at school, but that was a long time ago and I've forgotten most of what I learned about their use.
I'm now working with sensors and PLC based control systems driving hydro-electric turbines. I think being able to look at the waveforms of sensor signals and check for noise etc would be useful in troubleshooting applications. I've got a cheap USB oscilloscope (SainSmart DDS120) so: where are the best online training resources for learning how to use an oscilloscope?


texts: Memory layout problem when debugging, flashing works fine

texts:
My openocd configuration script:

# Configuration mode
telnet_port 4444
gdb_port 3333
source [find interface/ftdi/olimex-arm-usb-tiny-h.cfg]
adapter_khz 0
source [find target/at91sam7x512.cfg]

# Command mode
init
reset init

What my gdb session after starting openocd in another terminal looks like:

Reading symbols from /home/sw3/arm_workspace/Linuxization/main.out...done.
(gdb) target remote localhost:3333
Remote debugging using localhost:3333
warning: Overlapping regions in memory map: ignoring
0x00000050 in ?? ()

With different openocd configuration options and different openocd version, the same source, includeing the linker script, work fine.

What does this warning mean and where should I be looking to correct it?

Just some more info, to show the physical memory layout. Strangely, telnet communication reports banks as 0 and 1, while gdb monitor command reports two 0 banks:

(gdb) monitor flash banks
#0 : sam7x512.flash.0 (at91sam7) at 0x00100000, size 0x00040000, buswidth 4, chipwidth 0
#0 : sam7x512.flash.1 (at91sam7) at 0x00100000, size 0x00040000, buswidth 4, chipwidth 0

Later the debugger breaks normally at main(), but stepping produces:

(gdb) step
Single stepping until exit from function _user_app_start,
which has no line number information.
stepi ignored. GDB will now fetch the register state from the target.

Program received signal SIGINT, Interrupt.
0x00110000 in _user_app_start ()

Those symptoms hint something to anyone?


texts: Is it possible to combine the power of two power supplies to increase the total current and voltage


texts: What does the term "fixed" mean on the radio spectrum?

texts: On the United States Radio frequency allocation chart, the term "fixed" radio comes up a lot. What does that mean? Who is allowed to used "fixed"?


texts: Matching a 3W+3W audio amplifier with 2x6W speakers

texts:
I've picked up a pair of secondhand Sanyo micro hi-fi speakers (rated 6W, 4 ohms impedance) and I'm looking to build a simple bluetooth audio set-up using a preassembled bluetooth digital amplifier (link).

The amplifier board runs from a 5V micro USB power source and, according to the specifications, expects 2x3W speakers at 4-8 ohms.

As there is a mismatched power, I'm trying to work out what would happen if I just connected them as is. Would there be:

1) The speakers will only output a low volume

2) The speakers will go to full volume, but the sound will be very distorted.

3) Something else??

Based on research, I think that option 1 would be the outcome - am I right? If so, the volume produced may in fact be ok - the speaker will be needed for a 4m x 5m room for occasional use at modest volumes. Is this realistic?

Happy to receive any other suggestions for an alternative amplifier board, or if it could be easily modified.


texts: How to build a constant magnetic field source for a "railgun"?

texts:
I'm trying to build a device similar to railgun. It will have two rails and a conductive movable bar in-between. At one side, I'll provide voltage source and a resistor. If I put it in a strong enough magnetic field, it will move. The idea is that the device will work as demonstration of forces behind an electric motor, so I don't require high speed for the bar.

Here's a sketch:

So, I've got voltage source E, resistor R, bar whose length is A and magnetic field B.

If my calculation are correct, force when bar isn't moving should be  $F_m=IAB$. I don't require much force, so I guess that 5 mN would be more than enough. The power supply could be a problem. I should be able to get up to 1.3 A without much problems, but anything higher will be problematic, since I can't get a good match between resistor power dissipation and limitations of my power supply.

Since I can't get a perfect constant field, I'm going to have to compromise. I expect the field to drop linearly with A, but on the other hand, force will also get stronger linearly with A, so the differences should cancel themselves out, if I manage to do everything right.

Now about the field source itself. Most obvious sources are natural magnets or electric magnets. I can get natural magnets of various sizes but I don't have their magnetic field strengths. I found several types of magnets in local electronics stores. Their compositions are listed as AlNiCo500, NdFeB and SmCo5, so which one would be a good choice?

Another option would be to make an electrical magnet, but I'm unfamiliar with them, so I don't know where to start.

I'm also open to other means of generating a magnetic field, if I missed some.


texts:
I bought another soldering iron, very expensive to me. I am very exciting about it. Upon receiving it, My heart is broken. First, I saw the label, 220V; Our AC voltage is 110V. Tried it, doesn't work. Not even heating up.

With a heavy heart, I disassembled it, trying to fix it. Great news, the heating element is measured 62 ohm, so It should work with 110v. I have tried to change 40K to 20K, and 1K to 500, but it doesn't work.

Here is the schematic that I got from tracing the PCB. There is a MCU supposedly used to controlling the duration of the triacs, thus giving it a variable temperature. Also, it's a 120W soldering iron. For me, I can live with fixed power @ 60W. what should I do here? I am not very familiar with AC circuit.


texts: In gEDA where can I see th elist of supported footprints

texts: I am using gEDA on linux and I want to know what are the list of supported footprints in gEDA. For example i have a resistor which is supposed to be 0403, but what exactly do I put in as the footprint and how do I find  a reference to it?


texts: How to charge a battery + check voltage?

texts:
I know very little about electricity, so I'm sorry for the newbie question.

I'd like to take this car GPS for day-long bicycle rides. It only comes with a micro-USB cable to connect to a PC to exchange data, and an adapter to connect it to a car ligher to charge the battery. I assume the adapter uses 5V voltage, but I have no idea what current (amps) it offers.

I intend to buy a USB/wall power connector so I can charge the battery at home, but the battery only lasts 1h-2h anyway, so I need to hook up a second, bigger battery to the USB connector before going on a trip.

I know someone who uses this 6V/4.5Ah lead battery to power his GPS for several hours, and I have two questions:

How can I charge that lead battery?
How can I use a multi-meter to make sure the voltage isn't higher than 5V?
Is it really safe to have a battery that can send 4.5Ah to a device (the GPS battery, here) that only needs, say 0,8Ah?

Thank you.


texts: How suppress bounce-related turn-on spikes in DC bench power supply?

texts:
I'm taking a refining pass on my DC Bench Power Supply design. It generally
works quite well on veroboard, so I thought I'd move on to SMD PCBs and refine
the design while working out a few of the finer points. This project is a
"re-gut" of a classic HP 721A DC Bench Power Supply, presently looking like
this on the "breadboard". The small 35mm square PCB on the right is the
voltage error amp.

As I took a closer look at the turn-on transient, I noticed some semi-random
high-frequency (10s of MHz) spikes (maybe 5V peak) on the output terminals
during turn on.

The schematic looks like this. The V.unreg voltage source represents the transformer secondary full-wave rectified into a 500uF filter capacitor, all stock on the 721A.

Based on a few observations, I've concluded these are due to switch bounce in the old-fashioned panel toggle switch that directly applies mains (120V) to the transformer:

The frequency is at least an order of magnitude greater than the bandwidth of
my op amp, and maybe 50 times its cutoff frequency (~100kHz), as configured.
Also, regulation is rock-solid after the rails come up.
The spikes occur well before the bias power (+/- 15V) rails come up and even
before the DC bus comes up.
The same sort of spikes are observed on the "original" circa 1957 circuit
(I have seven of these 721As, long story :)
The spikes appear at irregular intervals, and sometimes don't appear at all.
They certainly don't appear at consistent locations accross multiple turn-on
events. Their amplitude is also inconsistent, sometimes zero, sometimes
a volt, sometimes 5V and more.

I'm not entirely sure how the spikes get through the pass device before it turns on, but I'm assuming its C to E capacitance is enough to couple them to the output.

I'm looking for advice on how to deal with these spikes. Here are some
alternatives that occur to me:

Quit trying to get a clean turn-on with a mechanical switch on a supply
with "always on" outputs. Just accept I'll need to disconnect any sensitive
loads before cycling the power and move on.
Design a snubber for the power switch that minimizes these spikes at their
source, somehow avoiding sending watts of power down the drain continuously
just to clean up the turn-on characteristics.
Work some other kind of magic a more experienced hand here can point me
toward :)
Get fancy and put an RC-delayed zero-sensing TRIAC or something like that between the switch and the transformer.
Add an output switch that would probably also have to be fancy, maybe a MOSFET controlled by a delay circuit to avoid that switch's bounce. This one would be somewhat contrary to the spirit of the project, which is to make it look stock but have modern innards :)

Anyone have any ideas how I can mitigate the spikes without going to active component-adding extremes?


texts:
I want to integrate/amplify a very small signal (relatively short pulses of 100ns to 4ms, necessitate high-bandwidth components minimum 40MHz+). The capacitors will be switched (shorted) when not in use, and unshorted at the right moment to integrate a pulse (finite time).
I wonder if there's any benefits to use a differential integrator topology like this (or on the contrary if it's not more error prone in the presence of mismatches):

Or integrate the differential signal directly using a single capacitor op-amp integrator like this:

Is it bad practice to use analog differential integrators considering capacitor mismatches are very likely to happen, even with C0G for example (tolerance +/- 1%)? Are there products on the market (for example "matched" capacitors) to overcome this potential issue?
Since an integrator output depends on time, I suppose the mismatch error will only grow as time goes by.
Yet, I suppose this topology (dual capacitors diff.) has some advantages since it is somewhat common.
Thanks in advance for any insight.


texts: Which kind of logic latch for an over-current H-Bridge disable?

texts:
I have a simple logic circuit requirement, but can't seem to match any standard flip-flop or latch to my needs (SR, JK, D, MS, level-sensitive or clocked, etc).

The circuit is to disable a H-bridge driver IC if an over-current situation is detected (via a Allegro ACS770 analog-output hall-effect current sensor input to a window comparator, creating the OverCurrent logic-level).

The DISable signal must stay active even if OverCurrent falls back to inactive, until the BridgeEnable is at least deactivated, or optionally deactivated and then reactivated.

Inputs:

BE (BridgeEnable), active-high.

OC (OverCurrent), active-high or active-low, I can flip the comparators either way.

Output:

DIS (Disable), ideally active-low.

This timing-diagram shows the functionality I'm looking for:

Suggestions?


texts: USB-C superspeed Signal pass through connection issue

texts:
The idea was to make a pass through super-speed signal connection (like a cable)between USB-C horizontal connector and USB-C vertical connector on a custom made PCB. where the device connects to the USB-C horizontal connector and host connects to the USB-C vertical connector. Below are the wiring connection and board layout. It is a four layer stack-up board and 90um thickness on both top and bottom layer.

Basically, I just wanted to create a right-angle setup due to space and design requirement. It is just a signal pass-through connection between host and device. I've followed 100R impedance followed with 0.15mm width. I heard 100R impedance wouldn't make much difference. Also, I came to know that I need to short D1_P to D2_P, and D1_N to D2_N for reversibility. It is working fine now.

But the problem I am facing now is

It detects only the high speed which is 480 Mbps not the super speed and Did I do any mistake on the wiring?

Your suggestions or guide would be much appreciated and helpful.

Thanks


texts: Video Display Buffer-VGA Port Interfacing

texts:
I am trying to get a basic understanding of how VGA port interfacing works.I have started reading SPARTAN 3 VGA Port Interface. I get the function of horizontal and vertical syncs, and the subsequent clock requirements, but I still don't understand the following few lines :

  A separate counter tracks the vertical timing. The vertical-sync counter increments with
  each HS pulse and decoded values generate the VS signal. This counter tracks the current
  display row. These two continuously running counters form the address into a video
  display buffer. For example, the on-board DDR SDRAM provides an ideal display buffer. This counter tracks the current
  display row. These two continuously running counters form the address into a video
  display buffer. For example, the on-board DDR SDRAM provides an ideal display buffer.

What does it mean by an ideal display buffer? Say, I were streaming "live" video, it would first be stored in the on-board DDR SDRAM? How do the two continuously running counters form the address (is this the address where each pixel's RGB data is stored) into a video display buffer?


texts: Does ideal Transformer transfer DC input voltage to secondary side, under NO-Load and Loaded condition?

texts:
Does ideal Transformer transfer DC input voltage to the secondary side, under NO-Load and Loaded condition?
 please you take DC input for a long time. Also consider two more conditions, 1st: for permeability tends to infinity, 2nd: permeability is very large finite value, but no loss at all.


texts: Average voltage (pwm regulated) out of motor voltage range?

texts:
My DC brushed motor is rated 4.5V-15V. My application requires the motor to spin with different speeds so I am using PWM to regulated the it. I will be supplying the motor with a 12V battery and using Arduino and a motor driver to regulate the motor. I am not sure what does this voltage range in the specification of the motor mean. Does this mean that regardless of the duty cycle it will be OK since I am using 12V battery? Or does that mean that the average voltage (e.g. 25% duty cycle, that means average 3V) needs to be inside 4.5V-15V? I think that since the battery is 12V, its ok because the voltage on the motor is going to be 12V(when ON) and 0V (when OFF), but I am not 100% sure and I need to be :)
And one more thing. Is the PWM from the Arduino (490Hz) that controls the motor driver the same as the PWM frequency of the motor driver that controls the motor? (490Hz seems kind of low to me)


texts: Can pulsating DC be used for induction heating?

texts: I want to make an induction heater work using a 12 v, 35 A-h battery(used in cars). I don't want to use an inverter. Will a pulsating DC input to the induction heater make it work?


texts: Transistor with different voltage in colector and base

texts:
I have a small LED of 5mm and an arduino powered by 9V. When I connect the LED to Vin (9V) using a 330 ohm resistor the LED brights very high. When I connect the LED to 5V (from arduino) using a 330 ohm resistor the LED brights very low.

Ok, that's supposed to happen.

Now I use a transistor 2n222 to power the LED. The problem is that if I use 5V or 9V (Vin) to power the LED it gets the same brightness. In the base I am using a digital pin sending HIGH.

Why does the transistor does not allow my LED to get brighter when the collector is connected to 9V source power?


texts: Just read here that Samsung has produced a camera sensor with a pixel size of 0.8 micron ie 800nm. Is it possible, or useful, for the pixel size to go below the wavelength of the light being imaged? For example, would 350nm size pixels be of any use sensing (say) green light at 530nm? Or have we reached the limit?


texts:
I plan to use SK6812 RGBW LEDs for my projects.
There was a question of reliability.
What happens if one of the pixels fails? Will the signal go further?
If not, which way to look?


texts:
I am considering a thermal design and due to space requirements I was considering different orientation of the heat sink, namely putting it bottom down, obviously, and puttin it on the side as in figures provided. I've seen a similar approach with water cooling but I am wondering if this would work as well and if the cooling effect is the same? Anyone had any experience with this?

NB: I am using forced air cooling.


texts:
I am wondering what the "Transfer" column indicates in this spec sheet for the Keithley Model 2002 DMM, and how it should be incorporated into any uncertainty calculations.

Thank You!


texts: I have an ATX which the yellow wire is "+ 12 v ,18 amp" and "blue is -12v , 1 amp". When I use them together I got 24 v but I am confused how to calculate the max ampere. How to calculate the max amp?


texts: Why off-line power supplies are called so, like they are "off the line"?

texts: My understanding is that "off the line" means "not on the line". For example an internet user is offline, meaning "not connected". However "Off-line power supplies" are directly connected to the grid (without line frequency transformer). Who coined this strange term?


texts: What is the best way to find the resistances values quickly?

texts:
This is the summing amplifier. I want a quick and easy way to find the resistances  values (Standard 5% Resistances). I used traditional way which is plug and try but it takes too long.

This is the gai I want


texts:
I recently acquired a couple vintage simplex clocks that used to be in a high school. They were part of a clock system where a master clock controlled the whole operation of slave clocks.

There were basically three systems: impulse, wired, and electronic systems. The clocks I have are electronic systems, where there is only a 110V AC plug. The clocks have a continuous motor and to keep them at the correct time (in case power wasn't a truly clean 60Hz) was to send signals over the electrical lines. On the limited information I have, I believe this signal was 3510 Hz. Two different durations of signals were sent. 1) An 8-second pulse at 57 minutes, 54 seconds on the hour for hourly corrections and 2) a 14-second pulse at 5:57:54 am/pm for 12-hour corrections. These pulses energized a solenoid that caused certain gears to catch and rotate the hands of the clock to the correct positions.

I can easily code up a program that sends audio signals at the specified frequency for the needed durations at the correct time but don't know how to send those over my home electrical lines (I only had a circuits class in college.) Any ideas on how to implement a home-brew inexpensive solution to send these signals?

EDIT: Here are some photos of the clocks in question.


texts:
I plan to use ACF bonding (hot-bar) to connect a display panel to a simple FR4 PCB.
As the circuit is very small and space optimized, I've positioned vias on some of the pads. If I would do use re-flow to connect the connector to the pads I would need to plug the vias with epoxy so solder won't run to the other side.
I would like not to epoxy fill the vias as this raises the cost of the PCB.
Will having non-plugged vias on the pads be a problem when doing ACF bonding?


texts: Logic Circuits Vs Transistor Power Circuits

texts:
I have need to invert a signal to drive fets with hard/fast rise and fall times.  I was told in another thread to use an inverter (NOT chip).  This makes perfect sense to me since logic chips are always hard ON or OFF by design.  But I've never worked with logic chips before.  All I've dealt with is 555s and transistor/fet power circuits.  Are there any 'gotchas' or special things I need to know to implement a NOT chip into a 555 output to switch a FET without any hiccups?  For that matter, are there any 'gotches' or things in general that apply to logic circuitry that someone with my background wouldn't know and might stumble on?

Jim


texts: Atmega328 resets when I try to turn off an AC fan using relay

texts: I have connected an array of 6V relays to one of the digital pins of my Atmega328 microcontroller via a driver ulN2803. I have connected two lights and one fan to the relays. The light bulbs seem to work completely fine but when I try to turn the fan off(especially when its on lower speeds) the microcontroller resets. Is this some kind of interference? I have broken the wire that goes to the regulator and fed it to the relay.


texts: Variable Reluctance Machines - what does the 6/4 or the 8/6 values mean?

texts:
I have been reading about electrical machines and keep getting these values in the examples but can't find what they actually mean. Is the first number the amount of stator poles and the second number is the rotor poles?

Any help is appreciated


texts:
I'm reading about amplitude shift keying, where 2^n assigned amplitudes of a carrier map to n bits per symbol. Unfortunately, most of the introductory material only covers OOK, where n=1 and decoding is trivial.

For an ASK system where n > 1, i.e. a system where the amplitude can be modulated by multiple levels and not simply on/off, how would a demodulator account for attenuation? In other words, how would a demodulator account for the ambiguity present where a low level could actually be a low level, or could be a high level that's simply a weak signal? Would one need to have heuristics, or maybe an occasional checksum that would only match if the inferred attenuation is correct?


texts: What is electrical insulation tape officially for?

texts:
Seemingly obvious question, but.  There are electrical supply companies that sell insulation tape in boxes of 12 or 24 units.  Seems that there's quite a demand for the stuff.
No commercial product I've ever seen uses insulation tape.  They use connectors, solder, heat shrink, etc.  I don't think that electrical code allows for wiring up a house by twisting the wire cores together and taping them.  You're not supposed to extend a lampshade flex by twisting on another length and covering the joint with tape.
I've used loads of the stuff for setting out road pin levels and concrete slabs.  It's very good for that.  I once saw a video of a 10KV splice being made and they used lots of tape for it, but that didn't seem to be the stuff from the DIY shop.
I'm curious as to what the approved use of insulation tape is?  And if there isn't one, why isn't it banned for electrical work?
STOP THE PRESS...
I've just put up a fluorescent light fitting.  It's from Wickes, a UK DIY store.  This is from the instructions:-

This is the first example I've ever seen of insulation tape being mentioned in a retail device.  I now know what it's for...


texts: Amplifier advice for speech sythesizer circuit

texts:
I'm designing a circuit that hooks up an SP0256A speech synthesizer to an AVR microcontroller and would like some help with the audio output amplification.
The datasheet describes the output as being "a Pulse Width Modulator that creates a digital output which is converted to an analog signal when filtered by an external low pass filter." An example circuit is given using an LM386

Another circuit I have is from a Maplin project that uses a pair of transistors

(top is 5v rail, right connection is to DIN socket which connects to a TV audio input)

As I see it the advantage of the Maplin circuit is that the speech synthesizer output can be combined with the sound output of the computer (a Commodore VIC-20), the complete circuit has a pair of DIN sockets just for this purpose.

I'd like to have a more compact circuit, can I use the LM386 in place of the transistors?

(edit: I've noticed the following on the datasheet re the Digital Output "Pulse width modulated digital speech output which, when filtered by a 5KHz low pass filter and amplified, will drive a loudspeaker")


texts: How does the quantization error decrease when the input signal is matched to the ADC input?

texts:
Assuming a theoretical example imagine that we at first feed a 1V pk-pk noiseless sine to a 10V ADC. And in the second case we feed a 10V pk-pk noiseless sine to that 10V ADC. As far as I understand from other questions, the quantization noise decreases in the second case.

Im trying to understand why by using the above example in a step by step explanation. How can we mathematically show explicitly that in the second case the quantization noise is lower?


texts: What is the purpose of a turntable's ground wire?

texts:
EDIT: I understand that the ground wire reduces hum. I'm not looking for a qualitative answer. I'm hoping someone can break it down for me Henry Ott or Bill Whitlock style.

Many turntables, such as the ever popular Technics SL-1200 mk2 have a separate ground wire which attaches to the chassis of the mixer or preamp you have your turntable connected to. It's also a popular modification to modify your turntable such that the ground wire internally connects to the shield of the RCA cable (which is connected to the chassis of your mixer/preamp already), eliminating the need for a separate wire.

My questions is, what is the purpose of the ground wire, especially given that it seems redundant given mods such as https://www.youtube.com/watch?v=3leKhyNinNk.

For the purposes of this question, assume use of Allen & Heath Xone 32 mixer.

Below are the phono input stage, and the point in the circuit where circuit ground connects to chassis ground in the mixer.

And here are some pictures of the inside of my Gemini XL 500 II.

The small black wire connects to the tonearm shell, acting as a shield for the four signal wires. It connects in turn to the rest of the grounds in the turntable via the springs, and in turn the the ground wire post on the outside of the turntable.

Note that the turntable itself has no connection to safety ground.

A visual/schematic explanation would be fantastic.


texts:
I am asked to design a full bridge rectifier with the following parameters:

Vin = 230 VAC
Vout = 18 VDC
Iout = 1 A
ΔVout = 500 mV
Efficiency at least 70%
The frequency of the voltage in the primary is 50Hz

In the course we were given the following formulas for a full wave bridge with capacitor:
\$V_{load} = U_2 - \frac {\pi}{(2*w*C) * I_{load}}\$
Where \$U_2\$ is the voltage in the secondary of the transformer (\$V_{in}\$ is the voltage in the primary.)
The second formula is:
\$Ripple factor = \frac {\pi}{(2*w*R_{load}*C)}\$
This is how I started:


texts:
I have a small vacuum cleaner motor, single-phase, AC commutator motor, 120V, 4 A Max., series wired (all coils, brushes connected in series), no start capacitor, two-pole field stator, with thermal fuse in series with circuit and taped against one of the field coils.

My issue is this: Originally not working/no power. I tracked down the problem to a blown thermal fuse. In the process of removal, I damaged one of the stator pole coils (they are apparently aluminum wire, so more fragile than copper). I decided to remove all the aluminum coil wiring and rewind both field stator coils with enameled copper magnet wire. After re-winding the coils and putting the armature/stator assembly back together, I tested it before complete re-assembly by using wired jumper/test clips to join unconnected wiring points.

It started and ran well--running it for 2 hours as a test. When I went to re-assemble, and soldering the wires to connect, I energized the motor again, but it moved only a small fraction of a rotation, then froze in place and sat there humming. There was no physical restriction on rotation-- it always turned smoothly by hand. I checked and rechecked various aspects of the motor a number times, such as brushes, commutator, connections but could find no obvious reason or change from when it ran upon first trial.

Can anyone offer any possible reasons why motor not now working when worked on first power up? What am I missing?


texts: How to find phase angle from transfer function

texts:
From the function:

$$H(\omega) = \frac{1}{(1 + j\omega)(1 + j\omega/10)}$$

How is the phase angle obtained when it has multiple poles to get:

$$\phi = -\tan^{-1}(\omega) - \tan^{-1}(\omega/10)$$

What rule of phase angles allows you to separate the two poles into two separate inverse tangent functions?


texts: Cleanest way to solar-power a string of outdoor bistro lights

texts:
I'm trying to hang some bistro lights on my balcony — specifically, the SVARTRÅ outdoor bistro lights from IKEA.
There's just one issue: the balcony has no power outlets, and I'm not going to snake a cable out my balcony door, so I'm trying to find a way to battery-power or solar-power these lights.
The lights take 5 V DC according to their power supply, and my kill-a-watt shows they draw 0.025 A at 120 V from mains when powered. I know enough about electronics to know I could power the bulbs by splicing in a D battery holder with 4 batteries in series, but I'd like to solar-power the lights if possible. My questions are:

Even though the power supply is rated for 5 V, would it be safe to give the bulbs 6 V? It would make it easier to test my setups with them without worrying about blowing them.

What combination of a solar panel/battery could I use that would be relatively clean while also giving the bulbs enough power to be turned on all night if desired?

EDIT: Some more info about the lights from a relevant FCC report on the power supply:

LED driver: KMUV-050-060-NA-2
Rating

Luminaire: 5 V DC, 3 W
LED driver input: 100 – 120 V, 50/60 Hz, 0.09 A
LED driver output: 5 V DC, 1.2 A, 6 W

Class

Luminaire: III
LED driver: II


texts: What does this triangle/diamond schematic symbol represent?

texts:
Could someone please tell me what the symbol ringed in red represents?

I know it has ON Switch pointing to it, but the symbol has other lables in different parts of the document.


texts:
Preface, I'm a plant engineer and my background is mechanical engineering. My current project requires me to find some pressure sensors for my compressed air lines and this is a pretty new territory for me. These sensors will be located in a dry room, same room as our compressors and PLC; so no running long wires or having to worry about water. I'm pretty set with the specifications of the sensors, now what I'm stuck with is choosing between two connection types. As an ME I'm not terribly familiar with the different connection types.

The site I'm looking at offers two connectors:

a DIN 43650 (DIN 175301-803C) connector

an M12 Connector

So my questions are:

What would be the advantages/disadvantages of both? From what I've found, M12 is better for harsher environments, like from a washdown; but other sites mention that the DIN connector is also capable of sealing from water. It also seems to me that M12 is more secure due to screw connection. How does the DIN connector keeps itself secure?
For my application, does it matter which one I choose?
Are there any effects to the electrical signal between the sensor and my PLC when choosing one connector to another? I'm using current to sense the pressure.
(bonus) What other connection options are commonly used among electrical engineers for connecting small sensors and actuators?


texts: Is it ok to cut the USB 3.0-specific lines on a USB cable?

texts:
I have a USB 3.0 micro cable in an assembly (below) where it attaches to a PCB on a sliding tray. Unfortunately, in the physical prototype, the cable is too stiff and causes the tray's stepper motor to struggle and stall.

Ultimately I will switch to an FPC-cable solution to address this properly. However, I was wondering if in the short term I could simply strip the PVC housing and shielding, and cut all USB 3.0-specific cables, leaving just the thin D+, D-, and 5V / GND wires. (The connection is to a raspberry pi which doesn't have USB 3.0 anyway).

Is it ok to cut the USB 3.0-specific wires and leave them floating? They have their own housing and are still pretty stiff even after the PVC is removed. I'd like to minimize the strain on the stepper as much as possible.


texts: purpose of outer sheath in Foiled Twisted Pair network cable?

texts:
What is the purpose of outer sheath in FTP cable, i.e. individual pairs already have the shielding and thus both crosstalk between the pairs and alien crosstalk should be eliminated?

In addition, how is screening(for example SF/UTP or S/FTP cable types) different from foiling(for example F/FTP type)?


texts:
I'm trying to control the temperature of water heated electrically.

On devices sold commercially I see that temperature is not being controlled, and the heating elements are either turned on or off (based on the feedback from some thermostats), probably because it is expected that the hot water will be mixed with cold water afterwards.

For a project I need to control the temperature of the water by controlling a heating element, using a power around 5KW - 10KW, and I guess I must do that by switching the power using some kind of SCR or Triac.

What would be the right approach to do this? Any help that leads me in the right direction will be very helpful.

Thanks in advance.


texts: STM32 USB - Delayed transmit when payload length = 256 (or 512, or 768...) bytes?

texts:
I am implementing USB communications on a STM32F105, using ST's USB Library v2.1.0.  It communicates as a CDC class Virtual COM Port ("VCP"). I'm using the embedded Full Speed PHY.

I've started with ST's VCP example project, which is a serial-to-USB converter.  I have it working well except for one issue that I suspect may be a bug in their library code.

Their USB driver exposes a circular buffer and buffer pointer. The application is supposed to put data into this buffer, which gets noticed by the driver and is acted upon. Here is the function to populate the buffer:

uint16_t VCP_DataTx (uint8_t* Buf, uint32_t Len)
{
    uint32_t i;
    for (i=0; i<Len; i++)
    {
        APP_Rx_Buffer[APP_Rx_ptr_in] = Buf[i];
        APP_Rx_ptr_in++;

        /* To avoid buffer overflow */
        if(APP_Rx_ptr_in == APP_RX_DATA_SIZE)
        {
            APP_Rx_ptr_in = 0;
        }
    }
    return USBD_OK;
 }

This works to send up to (at least) 1024 bytes of data, except if the data length is an even multiple of 256 bytes.  In other words, I can use this function to send 255 or 257 bytes just fine (or even 1023), but if I try to send 256 bytes it fails. Or 512, or 768, etc.

The failure mode is that no data is sent over USB until there has been a total of 4096 bytes passed into their buffer, and then it all gets transmitted at once. When it's working correctly, of course, the data gets transferred immediately.

There is a list of known bugs here. I've incorporated them, but it hasn't fixed this problem.

Does anyone know a solution?  I would prefer not to debug ST's driver code...


texts: Should all Combinations be included in a truth table?

texts:
I have been Learning about the IC-7490 Decade Counter which has 4 reset pins meaning 16 combinations, but the truth table can be compressed into just 4 Rows as I have done here:

Is this fine or should I mention all the other combinations? What is recommended?


texts: Li-ion vs Li-Po batteries cut-off protection

texts:
I am confused with the differences between Li-ion batteries (like 18650) and Li-Po (the flat ones).
I know that basically they are both lithium ion, but when I want to buy I see that LiPos have always undervoltage protection, and they should not be used if voltage is <3.0V, whereas 18650 Li-ions can be with or without protection circuitry and the cut-off is around 2.5V-2.6V (if there is protection circuit.)
Is my statement correct?
In general, can I replace a Li-ion with LiPo in a circuit?


texts: Connect two-function brake light to three-function car circuit

texts:
I need to replace my 12VDC (bulb based) brake lights but I am unable to find a three-function light (Running/Brake/Off) with the same specs. I did however find a two-function light LED fixture (ON/OFF) with the exact same dimension.

Similar to these:

I want to install the two-function LED based light brake in my car but using it as a three-function light.

I thought of building a small circuit that gives the light fixture max 50% on each wire using a resistor and adding a potentiometer for configurable dimming.

So when the car is running the LED light gets max 6V via wire1, and when I brake, it get max 12V via both wire1 + wire2.

Does this approach make sense? Can you suggest anything else?

If it does, I have no idea how to build that circuit starting from my three wires, as simple as it sounds.


texts: Can anyone properly explain me the characteristic curve of the p-type JFET?

texts:
I know how a MOSFET works. But recently I wanted to know details about JFET.

When V(GS) = 0 volts there will obviously a current flowing through the p-type channel. What confuses me is how the drain current is reduced when a positive voltage is applied. The gate terminal is connected to the n-type material. So, a depletion region will be created. But it is not narrowing the p-channel path that existed at V(GS) = 0 volts. So, how the drain current is reduced?

Please, someone, explain to me how this is happening.


texts: I know it is to protect sensitive load, but doesn't the zener diode in the power supply already do that? zener diode inside the power supply already limits the voltage to its breakdown voltage. Why do we need to short the powersupply in order to protect the load?


texts:
If I'm sending UDP from a microcontroller to another (both have built in MAC, STM32f4 Discovery boards to be precise), must I have a PHY attached to both or can I get away with only sending a MII signal from one to the other? From what I have gathered, within small distances this should work.

On a larger scope, I'm trying to figure out what exactly makes UDP, well, UDP.


texts: Synchronous Incomplete Assignment or How is Register Retention achieved

texts:
I just realised that Latch creation upon incomplemete assignments only happen in a non clocked enviroment.
So far I have written all my synchronous code unnecessary avoiding incomplete assignments like this:

if rising_edge(clk) then
  if X then
    if Y then
      reg <= '1';
    else
      reg <= reg;
    end if;
  else
    reg <= '0'
  end if;
end if;

This works fine for me.
But for bigger constructs, explicit register retention like here,

else
  reg <= reg;

adds a lot of bloat to my code.

So I'm wondering if there is any difference at all in omiting the else statement(1).

Also how is "register retention" despite of a clock edge realised in the hardware itself(2)?

Normally the clock should update the register every cycle. Is the retention implemented like the explicit code above, with a mux between register output and '1', or is there some kind of disable for the register. (I remember from my digital design class that gating the clock is a bad idea).

Thank you for your Insight!


texts: Which "silkscreen" process for home-made PCB prototypes?

texts:
For hobby and learning purposes, I do some PCBs at home, using photo-resist positive development (mainly just single/double layer).

Obviously, I realized that most professional PCBs have silkscreen labeling, so I started to read a bit about it. I've mainly seen 3 processes:

PCB printers/CNC: That seems to be the easiest, but it's quite expensive to get.
Silk printing: Seems very time-demanding, as to generate the "silk" screen would take long time for a single usage.
Ink transfer: Not sure about it, or how it works.

So my question is: What process is adapted for home-made PCB silk-printing? Is that even something usual? Where to get some further info about it?

Some related questions:

Acrylic vs. Epoxy Silkscreen?


texts: Turning on circuit when headphones are inserted

texts: I'm using a split supply, using 2x 9V batteries for a headphone amplifier. In lieu of an on off switch I'd like to just turn on or off when I put in the 3.5mm jack. Unfortunately the female jacks I've seen all have  normally closed switches. When the user inserts, the switches open. I can't figure out a low power way to use a closed circuit to kill the power! I feel like this should be very simple but I'm coming up with complicated solutions like xoring the input and using a SSR, but SSR have 1-1.4V drops...ideas?


texts: Altera MAX10 Clock primitives without synchronization?

texts:
Irrespective of the relative evil of gating clocks in FPGAs my understanding was that one should synchronize the enable signal to the clock being gated by means of a flip-flop chain.

However, while studying the documentation for the MAX10 device I stumbled over the following section: Clock Enable Signals where the figures 5 and 6 seem to indicate that no synchronization seems to be necessary.

Do I miss something?


texts:
I have an 18V 1.5A mains transformer (outputs around 30V peak with no load at 50Hz) followed by a full-bridge rectifier and a filter capacitor:

(there would be a schematic here if SE allowed me more than 2 images)

Now I need a negative supply (which will be regulated to -2V with LM337 and draw around 10mA, so it should provide at least -5V). For this purpose I added a negative charge pump:

At first it seems to work fine, the voltage at the output of the charge pump goes to around -27V after a few periods, however as the current is drawn it starts to sag and slowly approach zero volts. When I was trying to figure out what is wrong, I noticed that at the same time the voltage at the main filter capacitor rises from 30V to about 60V, which is undesirable. It seems I got double the input voltage, but not where I wanted it. To illustrate, this is a graph from LTspice:

Is there any way to prevent this behavior? To keep the filter capacitor at 30V maximum while keeping full-wave rectification (i.e. the 18V 1.5A capability) and at the same time supplying a workable negative voltage for a small load via a charge pump? I don't want to use an inverting DC-DC switcher in order to avoid extra noise.

(Sorry if I misused a term or two, I am a hobbyist still learning this stuff.)

Last minute observation: I noticed this behavior only happens if I draw more current from the negative rail than from the positive rail, so I guess one way around the problem would be to design the rest of the circuit so that more current is always drawn from the positive rail. However, I don't like the idea of positive supply rail potentially shooting from 30V upwards damaging other components, and I would like to prevent it altogether if possible.


texts:
My first electronics project in over a decade involves a Raspberry Pi 3 and two illuminated buttons.  I want to understand what resistor I need for the LEDs, if any.

The illuminated buttons have three pins which I believe are:

+12 V
Signal
0 V

Configured this way, the LED is permanently lit.  If I switch pins 1 and 2, the LED lights when the button is pressed, but I don't know how this affects the signal.  Could I simply switch them?

The LEDs are rated for 14V and a continuous 10A.  The salesman convinced me that a Raspberry Pi would be fine with these specs.  I have confirmed with a power supply that 3.3V is sufficient to light the LED.

Given the LED has such a high tolerance compared to what a Raspberry Pi can supply, do I need a resistor, and if so, how do I determine which one and which pin do I attach it to?

EDIT: The project is to create a Big Red Button™ that when pressed, activates Find My iPhone, Play Sound on my wife's phone.  It's a daily necessity.  Ideally I'd like full control over the LED to use it for feedback, but if that's a risk to the Raspberry Pi I'll settle for lit when pressed.


texts:
I need help with the following problem:

Find range of resistance R4 and voltage U4 so that the range of current I is $$I \in [-3A,-1A]$$

E=5V,
   E4=6V,
   Ig=1A,
   Ig4=-3A,
   R1=2ohm,
   R2=3ohm,
   R3=5ohm

Firstly, I set current I=-3A. Setting potential V3=0 V, current I23=0.25 A.

Using Kirchhoff's law on node 2 I12=1.25 A. On node 1 I14=1.75 V.

Now potential of nodes are V1=5 V, V2=1.25 V, V3=0 V V4=1.5 V.

With potential of nodes method on node 4, R4=2.09 ohm. Then, U4=-4.5 V.

In my book's solution, it says that R4 starts from 0.22 ohm and U4 starts from -4.5 V.

Could someone check this?


texts: LTSpice capacitor network simulation question

texts:
Below is a circuit build in LTSpice. It is capacitor network simulation.

What is of interest to me is the voltage at node N005. A voltage controlled switch rises the voltage of node N003 to 29.42 Volt as expected from voltage source V1.

In a series capacitor network the voltage is highest at the least capacitance value according to formular:

Vc1 = Q / C1
Vc4 = Q / C4

Vtotal = Vc1 + Vc4.

However, node N005 stays at zero (2 mV) all the time. I would expect a higher voltage at N0005. Even using non ideal capacitors does not change this behaviour. Can you give me a hint why this occurs? Measuring at a real lab experiment shows 26.5 volt at N0005.


texts: Problem with new bicycle front led light and old bulb back light

texts:
I had a problem with my front bulb light at my bicycle. So, I bought a new one (LED) for the front, but somehow, the back bulb does not work anymore. I have checked the wires for loose connection, so I want to rule that out. Also it (the back bulb) was working in the past, so I want to rule that out as well.
I am thinking now about the following to things:

I think, the front and the back lights are connected in a parallel connection. So, both the GND and the + from both the front and the back light should be directly connected. Is that true? I could only measure GND here.
Parallel connection also implies, the mix up of dynamo and back light at the connection ports of the front light should not matter. Right?
Could the difference of a bulb light at the back and a LED front light be an issue?

Thanks for your help here, guys.


texts:
I am trying to write a verilog code for a Fibonacci sequence generator. It's output will be nth Fibonacci number where n is the output of the count. The code works for count = 2. But when the count increases, all the specified register values goes to 0. I am suspecting the error might be in the always block that contains the case statement. How can I solve the problem?

module fib(clk, reset, count, out, prev,present, temp);
// This module generates nth fibonacchi number, where n is the output of the count
    input clk, reset;
    output reg[7:0] count;
    output [7:0]out;
    output reg [7:0]prev, present, temp;
    //state register
    always @(posedge clk)
        if(reset==1) count = 1;
        else count = count + 1;

    //next state logic
    always @(count[0])
    case(count)
    8'b00000001:begin
                prev = 8'bxxxxxxxx; present = 8'bxxxxxxxx;
                end
    8'b00000010:begin
                prev = 8'b00000000; present = 8'b00000001;
                end
    default: begin
                temp = present;
                present = present + prev;
                prev = temp;
            end
    endcase

    //output logic

    assign out = present;

endmodule


texts: design a 90 degree hybrid coupler 2-8GHZ

texts:
I designed a 90 degree hybrid coupler in hfss, in 5~6 GHZ.
S₁₁ & phase difference are okay, but S₂₁ & S₃₁ don't match.

What change should I make in the form to improve matching between S₂₁ & S₃₁?


texts:
I have a tablet that has one USB-C exit.  I need to connect power supply and USB to LAN adapter at the same moment.  I have bought the only USB-C splitter I could get and it does not work (despite having the chip it does not support on the go USB devices).
I am thinking to reuse the product so it would support my requirements.  Can someone suggest a circuit to do that?  I am thinking about two possible solutions:

complicated solution: a circuit with a chip that truly splits USB channel into two
simple solution: connect data between tablet and USB to LAN adapter and connect power supply to both

Is simple solution possible at all?


texts: What's the next step in my track to become an Embedded Hardware or Hardware Engineer?

texts:
I'm a student studying computer engineering  , I'm in love with hardware stuff /logic gates design ... etc
What I studied till now is :

Electronics
IC fabrication
Logic circuits design (sequential , ... )
Error detecting & correction in logic circuits (parity check , ...)
HW design
Computer architecture (Control unit ,execution unit ...etc ) after
finishing it I was able to design a microprocessor
MicroProcessor (Z80 , 8086 , ..)
Computer Interfacing (Buses , creating cards , motherboards ..... )
Digital signal processing

ALL of the above courses I studied them hardly, understand them fully

I also made some projects using AVR uc ,

So what do you think the next proper step for me ??

Update 1 :
I've the following software background :
Software Engineering
Java, C , C++ ,C#
C for embedded
Data structure & Algorithms
Operating systems
AI
Image processing


texts: Charge Model vs Voltage Model for Piezo Electric Sensor

texts:
The following document describes signal conditioning circuits for Piezeoelectric sensors. I was interested in knowing which model should I use when designing signal conditioning circuit for piezelectric sensor.

http://www.ti.com/lit/an/sloa033a/sloa033a.pdf


texts: CMOS circuit that will output an analog voltage proportional to the duration of a pulse at the input (pulse-width detection)

texts:
I don't have a strong background in electronics, so this task is challenging for me.
I need to build a circuit that will get an output like this. In my circuit, I can only use voltage sources, resistors, capacitors, and transistors. The max. total capacitance is limited to 10pF, the total resistance is limited to 100kOhm. The smallest size transistor is 0.4um/0.35um.

Could you help me to figure out how the circuit should look in the end?


texts: Is there a standard or "safe" distance between PCB components?

texts:
I am (still) designing my first PCB and, according to prices listed on websites, the smaller the board the cheaper it is. That is, batchpcb charges per square inch. goldphoenix will print "as many as they can" on an 100 square inch board. Smaller is cheaper. Got it.

So should I try to cram as much as I can in a small space? Obviously one can go overboard doing this, but in all reasonableness, the point stands. Is there a standard guide for minimum distances between components? And are the standards based "this makes it easy to solder" or more technical problems (capacitances, inductances, sparks across components) that are too close together?

For example, one comment on this board from sparkfun says:

  "These don't look like they're spaced
  at standard banana jack spacing. Isn't
  that important anymore?"

  "its low current (5 amps) which
  shouldn't be enough to spark across
  the terminals at those voltages"

  "I think the point is that most double
  banana plugs have a spacing of 0.75".
  The banana jack spacing on this board
  appears to be about 0.5"."

All implying that there the board has a poor design. But poor based on what?


texts: How to design a buck converter with feedback?

texts:
I design a simple circuit activates fan when processor heats up and then control rotation speed. I got the idea to create a buck-mode step-down voltage converter. However, I would like stabilize output voltage of the converter.
But I can't interfere in the PCB with microcontroller and I have only +5V, GND and PWM pins.

Do you have any idea on how to do that?


texts:
I am trying to flash an Ambiq Apollo via SWD.

The problem is that my debugger is unable to connect to the board.

Initially, i though that the SWD pins would simply be remapped by software on the MCU.
Thus, following this post, i tried to hold down nRST while powering on the board.
Yet, no connection possible.

What additional ways are there to disable SWD?
What else can i try to enable debugging on my board?


texts:
I've put together an lm386 audio amplifier circuit as shown in the image below. The volume was good when hooked up to the 9V output on my trainers breadboard, but when I hooked it up to a 9V battery, I couldn't get any sound out of it. I measured an 8V voltage drop when between the positive and negative end of the circuit on the breadboard and a 2V voltage drop with the same circuit powered by a 9V battery.

This makes me wonder where all the power is going (if not through the audio amplifier) in the battery-connected circuit. I am guessing that there is greater current from the breadboard, which pushes electrons through the circuit, but would like a more definitive answer.

credit AfroTechMods


texts: H bridge working with led but not with electric motor

texts: Noob here. I am trying to make a car which i can control remotely from the internet (ie. lan). I have a H-bridge circuit which has all NPN transistors (bc 547B and datasheet here: https://www.farnell.com/datasheets/410427.pdf). Here is the schematic for my circuit: https://content.instructables.com/ORIG/FDG/I6CS/HXVI3O2P/FDGI6CSHXVI3O2P.jpg?auto=webp&frame=1&fit=bounds (original tutorial here: https://www.instructables.com/BUILD-YOUR-OWN-H-BRIDGE-CIRCUIT-USING-NPN-TRANSIST/) except replace the tip transistors with the one i mentioned and for the resistor i used 1k ohm resistors and also i wasn't able to get the transistors working with a shared supply thiny (i had to put a resistor before each transistor because for some whatever reason it won't work if i share the base voltage from one resistor which may hint at what i am doing wrong). The circuit works as expected with 15 volt input voltage for the led (9v battery and 4 x 1.5 AA battery pack in series), but when i connect the electric motor, the motor wont spin. (the motor is this: http://www.mootio-components.com/motor-current-dc-voltage-150v-rpm-9000rpm-fa-130-ra-2270_refe_003836-1.5.html) Thanks in advance for the help!


texts: Permutation-based parallel-by-serial calculation of resistance in a circuit

texts:
We have employed a computational method for identifying order of receipt of signals from senders based on a telecommunications and/or EE technique.  However, we would like to find out which permutation-based technique in EE this stems from.

The technical report states the following:

“The approach is similar to computing resistance in a circuit, which is a parallel-by-serial procedure.  The parallel conductivities from all preceding components to a target component are all summed, within a permuted ordering of components, to determine the phase conductivity of the permutation, and then the order conductivity is formulated by cascading all the phase conductivities.”

Note, all the components have to be the same type, maybe resistors or capacitors, but differ by varying rating of their units (10 Ohms, 20 Ohms, 30 Ohms, ..., 500 Ohms).  However, you don't know their ratings, but rather, only a label like 1,2,3,4,5.   During the calculation, the order of all of the components in the circuit are permuted(shuffled), and all the resistance up to a target is calculated – but each component is once the target.

The application of this calculation would be employed for numerous e.g. circuit boards, where the goal for each board would be to determine if order 7-->3-->1-->2-->5-->6-->4 resulted in the greatest resistance.  Another board might have components with labels 12, 3, 55, 13, 92, and 105 (which in truth have different ratings, but you don't know what the ratings are).  Overall, you are trying to determine for each board what order of labels results in the greatest resistance.  Then over several hundred boards you can develop a picture of what the order is for labels which results in the greatest resistance (on average).

Is there a standard permutation-based technique in EE to find resistance in a circuit that is both serial and parallel?


texts:
I want to light a miniature  house …not “doll house”  that can be played with , but the models like the period miniatures found in museums.

The lights in all rooms should come on simultaneously but slowly, over a period of say, 2-5 seconds when a viewer comes within 12-15  inches of the model.
I don’t want the lights going on simply when someone walks past the model at 3 feet away.

Lights should stay on as long as the person is within that 12-15”  distance, then fade out slowly,  again, over about 2- 5 seconds as they move away.
If another viewer comes up while the first moves away, and the lights  dim a bit before lighting up again, or stay on, either way is OK.

Now for some background.  I don’t know much about circuits. My dad (deceased) was a EE and I sometimes watched him tinker with stuff and asked questions. Then I took a basic Electronic course in junior college, but that was many moons ago. I do remember some principles and terminology.

I came across a design called a “Fade-in, fade out “ ckt for LEDS.
( Link attached)
http://www.pcbheaven.com/circuitpages/LED_Fade_In_Fade_Out_Dimmer/

It’s the first ckt shown, with the “slight flaw”

I bought some breadboard stuff  and the parts on the parts list and used a 12v charger to power it. But I used a 2N2222 because my dad had a lot of those around.

The fade out works better, but the “fade in”  is a little fast, but at least not like the typical  LED sudden turn on (and off) .

Then I googled a lot on sensors and came across this Sharp sensor  GP2Y0A02YK which seemed what I wanted. It’s weak at 3ft  but seems to put out enough voltage at about 12-15 inches.

What I don’t know  (and finally have come to my problem) is how to make this turn on and off the fader ckt.

I decided to try this:  make the Sensor output turn on a second  transistor (also NPN 2N2222-- which I will call NPN-2 )  and put the entire fader ckt as the load in the NPN-2 collector . I really had/ have no idea if this is correct, but I figured a load is a load if there  is enough current to make it work.

The 12 v charger is the Vcc  ( I took the push button switch out of the Fader ckt and just made the 12v go straight to the resistor R1) , and made all the common points of the fader ckt go to the NPN-2 collector.

The NPN-2 emitter goes to  12v charger low side
The Sensor module itself is powered by 4 AA’s  and its output goes to the NPN-2  base to turn it on (or not).
And surprise of surprises, the whole thing actually works! Well, not great, but pretty well.
 So my questions are these.

1) Do I need resistor(s)  in the base of NPN-2? It seems to work with one and without one. If I should have one/some  there, what do I need?

2) How do I power the sensor module off the charger since it only needs 6v and not 12v?

3) How can I slow down the fade-in  a little more ?

4) ) Is there a better way to do this? I.e. a better design, better sensor, just scrap the whole thing and start over?.

And finally 5) You all can stop rolling your eyes now.

Thank you

Marie


texts: Should a off-grid wind charge controller be UL certified?

texts:
I recently bought a 2kW wind generator, 48V Charge controller and a UL certified off grid wind inverter for my Home based wind project prototype. My charge controller which I am using to rectify the AC output from the generator and to charge the batteries in not UL certified, but my inverter is UL certified. Is it safe to use it for the prototype? Any guidance is much appreciated.

P.s. I bought them via Alibaba


texts: Design a circuit using only 2 to 1 multiplexers that implements the function of an 8 to 1 multiplexer

texts: I'm not entirely familiar with multiplexers and I don't fully understand the concept of how I can make a 2 to 1 imitate a 8 to 1. Is there a predetermined/default truth table for multiplexers that I do not know about? Any insight would be greatly appreciated.


texts:
My car flasher circuit can be simplified like so :

The factory flasher unit is a standard 2 pin that plugs in series with the switch and the load (indicator lights).
I'm attempting to make my own flasher, and came up with 555 timer outputting a square signal to a mosfet, flashhing the load when the switch is closed.

My problem here is that I have this ground pin on the 555 timer circuit which essentially makes my flasher unit 3 pins instead of 2 pins. Also in this configuration the flasher is constantly flashing in the background, but not visible until the switch is closed.
How could I make it into a 2 pin system so that only when the switch is closed, the 555 circuit starts flashing ? Can I connect 555 circuit "GND" to the output of the MOSFET through a Diode for example ?
Extra info : the load will be approximatively 5-8 Amps.


texts: interfacing tcs3200 color sensor with STM32f746zg

texts:
I want to interface TCS3200 color sensor with STM32f746ZG. Since the TCS3200 outputs a frequency based on the amount of light received, I need some way to count the number of pulses for different colors to determine a color.

In CubeMX, I set PF6(s0) PF7(s1) PF8(s2) PF9(s3) and TIM2 ch1 input capture as (out) of the sensor. Frequency for timer 2, I selected to be 84MHz with prescalar 83 which will bring it to 1MHz (I am not sure whether I should do this or not). I also enabled TIM2 global interrupt in nvic window. Next, I activated TIM6 to measure time of 5s (timer f=84MHz, prescalar=41999 and counterperiod = 9999).

I have doubt about how to use these two timers inside the while loop, which HAL library functions to use here and how to use.

CubeMX is the source code generator and the IDE is Kiel5. Following is my setting for output frequency scaling and filter type outside the main function. If I am wrong, please correct me.

void TCSFREQ()

      {
    HAL_GPIO_WritePin(GPIOF,  s0_Pin,GPIO_PIN_SET);
     HAL_GPIO_WritePin(GPIOF,  s1_Pin,GPIO_PIN_RESET);
   }

void TCSRED()

      {
    HAL_GPIO_WritePin(GPIOF,  s2_Pin,GPIO_PIN_RESET);
     HAL_GPIO_WritePin(GPIOF,  s3_Pin,GPIO_PIN_RESET);
   }

void TCSBLUE()

      {
    HAL_GPIO_WritePin(GPIOF,  s2_Pin,GPIO_PIN_RESET);
     HAL_GPIO_WritePin(GPIOF,  s3_Pin,GPIO_PIN_SET);
   }

void GREEN()

      {
    HAL_GPIO_WritePin(GPIOF,  s2_Pin,GPIO_PIN_SET);
     HAL_GPIO_WritePin(GPIOF,  s3_Pin,GPIO_PIN_SET);
   }

void TCSCLEAR()

      {
    HAL_GPIO_WritePin(GPIOF,  s2_Pin,GPIO_PIN_SET);
     HAL_GPIO_WritePin(GPIOF,  s3_Pin,GPIO_PIN_RESET);
   }

Correct me if there is something wrong above.

As I am new to microcontrollers, I am struggling with how to count the number of pulses in a time period (let's say 5s). It would be nice if you would help me with my problem or suggest some alternative solution.

How do I count the no of pulses from output of that sensor?


texts: Communication in presence of noise: Why is the number of distinguishable amplitudes K*sqrt((S+N)/N)

texts:
In section VII: The Capacity of a channel in the presence of white thermal noise in his 1949 paper Communication in the presence of noise, C.E.Shannon says, that for a signal with average power
P, the total number of reasonably distinguishable amplitudes in the presence of white noise with average power N, is given by

$$K\,\sqrt{\frac{P+N}{N}}$$

where

  K is a small constant in the neighborhood of unity depending on how the phrase reasonably well is interpreted.

I wonder where above formula comes from and if it has any deeper theoretical background, since for me it seems just like a simple metric:  The Rx signal's amplitude has a standard deviation of

$$\sigma_\text{Rx}=\sqrt{P+N},$$

the noises amplitude standard deviation is

$$\sigma_\text{Tx} = \sqrt{N},$$ so above formula gives the factor by which the Rx's signals amplitude is larger than the noise amplitude that corrupts that signal on average. But why not compare the Tx signal's amplitudes to the noise amplitudes?


texts: Is there any RFID reader IC wherein I can select what protocols I want to read in a band ? Any kind of help would be useful.


texts: How can I filter out sunlight on a solar panel so that I can read a signal from a red laser?

texts:
So right now I have a small solar panel (4" by 4") and a red laser. I'm trying to design a laser tag system that doesn't follow the way that traditional laser tag is done. I want to be able to shoot a modulated laser signal from a long distance and have my solar panel hooked up to a micro controller and read the output from my solar panel. (I know a solar panel isn't the best option for a sensor, and I will eventually use something more practical like a photo diode, but the basic principles remain the same). When I am reading the signals on my solar panel, there is so much sunlight that it masks the laser signal that I am sending. So its hard to program the micro controller to read the signal when I don't know what the signal even is.

I have thought about implementing a band pass filter, so that only frequencies of the color light I am using get through the circuit, and then putting another modulation on top of my laser to distinguish it from the sunlight signals that also made it through the filter. It sounds like it would work in theory, and I haven't done enough test to confirm it, but I have a feeling this might not work due to my next point.

If the solar panel becomes saturated in direct sunlight, then my signals my not even be producing a recordable output on my solar panel. If that is the case, what would I need to do? I would physically need to block the sunlight in this case right? Like put some barrier over the panel that maybe on lets in a narrow band of light that is specific to my laser? It would just be easier to do this whole thing if there was just a way to completely block all sunlight. Then I would definitely know the output on my solar panel was my laser. Is this at all possible? My gut tells me no because that would be too easy. I guess I'm just looking to see if I am on the right track with this thing and would love any suggestion you guys have to offer.


texts: Amplifying a minuscule signal without external power source?

texts:
I recently came across this circuit :
http://sgitornado.altervista.org/diyirig.html

I tried to understand it, but I have several questions I can't really search for, as I'm an amateur and don't know the terms or what I am looking at exactly.

I don't understand why the circuit starts with such a small capacitor; doesn't this mess with the signal as it is output by the guitar?
Why are there so many resistors and capacitors in parallel, are these values just magic numbers or can we calculate them?
The point of the transistor is to amplify the guitar mic pickup signal, but are the 10mV output really powering this? This particularly bothers me as this value sounds way too small for anything.


texts: Why does Li-Po battery voltage drop under load?

texts:
I have very low background in electronics.

I have a Li-Po battery connected to an electric motor. The question is:

Why does battery voltage drop under load?
Why is each cell of a Li-Po battery limited to 3.0 V (discharging)?
Why is each cell of a Li-Po battery limited to 4.2 V (charging)?


texts: Help understanding simple voltage regulator output

texts:
I made a small circuit using LTSpice and want to try to understand the output.
My input is a 1.4V sinewave with a +10V offset (Vin = 10V + 1.4V*sin(2*pift)). The Zener Diode has a Breakdown Voltage of 6.2V

I can see that the Zener Diode breaks down immidiately. Is that caused by the 10V offset ?
How can I calculate the peak of the output voltage ?


texts: How to choose a relay for controlling a freezer/fridge with a uC?

texts:
I want to control a freezer using a microcontroller and relay, and be able to set a higher higher temperature for dry curing meats. I realize there are off-the-shelf solutions but I kind of want to build it from scratch. I'm familiar enough with microcontrollers and small signal relays, but I've never tried to switch mains voltages or inductive loads.  If the freezer draws 2A (AC steady state, at 110v, not sure what starting current is) what relay would you recommend, and how would you recommend I drive it? I'm thinking of using a 15-25A DPST relay for the load w/ 12V coil voltage. DPST because I'd switch both hot and neutral. And a 12V relay (with V_coil matching my uC supply voltage) in front of the power relay to drive the power relay.

Here's a selection digikey relays matching the power relay criteria I've mentioned... http://www.digikey.com/scripts/dksearch/dksus.dll?FV=fff40010%2Cfff80367%2C16040015%2C16040017%2C16040018%2C16040019%2C1604001a%2C16080007%2C16080008%2C1608000a%2C16080039&k=relay&vendor=0&mnonly=0&newproducts=0&ptm=0&fid=0&quantity=0&PV72=13&PV72=35&PV72=2

BTW, I'm comfortable wiring mains voltage. I don't mess around with it unless the circuit is OFF! I've just never interfaced my electronics stuff to my house wiring.

One point about DC power source:  I'll probably use a silver box from an old PC to provide the uC voltage and 12V relay supplies.  This will be on the same circuit as the power relay for the freezer.

I can provide more clarification if needed. Thanks.

Edit: One person I spoke to had suggested switching both line and neutral, and I'd read it on a forum somewhere as well (can't remember where).  I plan to keep the GND connection hard tied to a common ground throughout the system / house.


texts: Why do people say STM32Cubemx is full of bugs?

texts: I have worked with stm32cubemx for 2 years now, and I have found on forums people have mentioned that stm32cubemx is full of bugs? Why is that?


texts: AVRDUDE throws errors when attempting ISP with AVR Dragon

texts:
I've got an Arduino board that I'm trying to program via ISP with an AVR Dragon. I think I've got it all cabled up right (I made my own ISP cable by cutting up an old floppy ribbon cable), but when I attempt to connect avrdude I get the following errors:

sudo /usr/bin/avrdude -pm328p -c dragon_isp -v -v -v -v -P usb -B 1 -t

avrdude: Version 5.10, compiled on Jun 29 2010 at 03:44:14
     Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
     Copyright (c) 2007-2009 Joerg Wunsch

     System wide configuration file is "/etc/avrdude.conf"

     Using Port                    : usb
     Using Programmer              : dragon_isp
     Setting bit clk period        : 1.0
avrdude: stk500v2_dragon_isp_open()
avrdude: usbdev_open(): Found AVRBLDR, serno: 00A200007E77
avrdude: usbdev_open(): using read endpoint 0x82
avrdude: jtagmkII_getsync()
avrdude: jtagmkII_getsync(): Sending sign-on command:
avrdude: jtagmkII_send(): sending 1 bytes
avrdude: Sent: . [1b] . [00] . [00] . [01] . [00] . [00] . [00] . [0e] . [01] . [f3] . [97]
avrdude: jtagmkII_recv():
avrdude: usb_fill_buf(): usb_bulk_read() error No error
avrdude: jtagmkII_recv(): Timeout receiving packet
avrdude: jtagmkII_getsync(): sign-on command: status -1
avrdude: jtagmkII_getsync(): Sending sign-on command:
avrdude: jtagmkII_send(): sending 1 bytes
avrdude: usbdev_send(): wrote -19 out of 11 bytes, err = error submitting URB: No such device
avrdude: jtagmkII_send(): failed to send command to serial port

I've hooked the AVR Dragon to two different Arduinos, and they both have the same issue.


texts:
I'd like to know what does the term "piezo resonance impedance" mean. It is commonly available with the datasheets of piezo sensors such as this. Is it the same as the piezo transducer's insulation leakage resistance as shown in this link?

And how does this resonance impedance effect the response of the sensors.


texts:
I've been working on a soft-start circuit to solve an inrush current problem that is causing some sparking when I hotplug my power supply into my board. I played around with different solutions and this is the one I like the best so far. It adds a delay of 250ms between Vin and Vout on the power MOSFET on my load.

My schematic:

My simulation results:

I want to get some opinions from the PROS out there.

Now, since I'm only using M1 to drive M2, there is no reason to use a power MOSFET, am I correct? I could use a small current MOSFET to drive the other one.

Edit:

Updated shcematic thanks to Kaz:

Edit #2:

I'm working on a soft-start circuit to avoid some sparking when I plug it my external power-supply to my board. I'm using 2 P-channel MOSFETS and some RC circuit to control the gate on one of them whicl will help me control the gate on the power mosfet that willl feed my board.

This is my little circuit:

R3 = My Load. I'm using max 8A hence I am representing it with a 3ohm resistor.

R2 and R4 are there to bias my MOSFET's gate with a Vgs goign from 0V to -12V.

The problem I am having is on biasing M1. Currently Vgs is going from -24V to 0V, and I need it to go from -12V to 0V, otherwise I might end up damaging the device. a Vgs of -24V is too high.

The only thing I could think of was shifting the reference point of C1 up by 12V using a voltage divider but I don't know if this is recommendable.

Like this:

My only concern now is the behaviour of the MOSFET, no matter how slow I ramp the Vgs voltage, it is still acting like an ON-OFF switch. Any ideas?


texts: Circuit to detect presence or absense of current

texts:
I'm trying to come up with a bad-bulb detector for a circuit that will control the turn signals and brake lights in a car or truck. I'm defining "bad bulb" here as an open circuit, which is what typically happens when a light dies in a vehicle.

The allowable current range per output is pretty large: 100mA to 10A. This will allow the installer to use a single LED bulb on each output or several old-fashioned incandescents in parallel. In order for the MCU to detect a bad bulb, it only needs to know that current flowed or didn't flow, not necessarily how much.

Ideally, the circuit will have an extremely low part count and very inexpensive components (but still work in an automotive environment). This is mostly because the circuit will need to be duplicated several times on the PCB, so any excess will grow the size of the PCB and the budget. And the budget for this project is extremely small.

Here's one idea I've come up with so far using only passive components:

simulate this circuit – Schematic created using CircuitLab

When M1 is turned on, C1 charges up and power is available to the bulb. When M1 is turned off, one of two things may happen:

If the bulb was good, C1 will supply additional current to the bulb for a very short amount of time. NODE1 will very quickly drop to zero volts, which will cause NODE2 to also drop off quickly. If the GPIO pin samples NODE2 a few milliseconds after M1 was turned off, it should see a digital low signal. A low signal indicates the bulb is good.
If the bulb was bad, the only load to drain C1 will be the resistor divider R1 and R2. But those resistors are large, so the voltage across C1 will stay higher longer. If GPIO samples NODE2 a few milliseconds after M1 is turned off, it should see a digital high. A high signal indicates the bulb is bad.

Everything outside the dotted box is already committed in the schematic, so I'm just adding two resistors, two capacitors, and two diodes per output (D1 and D2 are just to protect the MCU from load dumps). These parts might add up to 25 cents per output, which is great. This is an adequate solution, albeit untested outside of simulation so far.

I'm hoping to get some ideas for clever ways to do this using even less components or for making it more robust. I would also appreciate critiques on the circuit I've presented above.


texts: I would like to connect several microcontrollers as shown in the circuit diagram below. The software makes sure that the PA1 pin always has the low or floating state.  It's a kind of open drain control. However, the ATtiny1616 still has a small voltage, up to 0.3×VDD, in its low state. This voltage is slightly different at each pin due to temperature differences and tolerances. This could lead to high currents if more than one pin switches to low. Would the circuit still work? If so, why isn't the small voltage difference from pin to pin a problem?


texts: Altium 17: Multichannel Design "contains floating input pins"

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I get

  Net SCL/SCK contains floating input pins (Pin U1.1-4,Pin U1.2-4)

as the only error after compiling the project but I don't know why.
The clock signal as well as V+ is shared among the different channels.
V+ doesn't rais an error probably because it's connected to the sheet's power port via an inductor.

What's wrong with the design?


texts: What are the advantages and advantages of ceramic and Langevin transducers for ultrasonic cleaners?

texts:
I have an old large ultrasonic cleaner with 5 ceramic piezo electric transducers (pictured below) epoxied to its tank's underside. They use around 40W of power each.

Newer ultrasonic cleaners, however, use the more massive Langevin transducers as seen here:

What are the differences between these two types of transducers? Also, what are their respective advantages and disadvantages for the application of ultrasonic bath cleaning? Is it worth upgrading my old unit to one that uses the Langevin transducer in terms of more cleaning power?


texts: Connect multiple, non-independent, RGB LEDs

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I’m trying to build a Lego Technic panel with some RGB LEDs (do you know they fit perfectly in Technic’s holes?) driven by an Arduino.

Anyway, my question is: how do I connect multiple (say, 9) RGB LEDs to be driven simultaneously? I want to use RGB LEDs because, although they all have to show the same color, this color may vary. There are tons of info about how to drive them independently but I’d like to light them up all the same, like they are a single one.

The LEDs I'm going to use are Elegoo 5mm common anode (datasheet) or common cathode (datasheet).

I know I have to use an external power supply, probably transistors activated by Arduino to power the LEDs and resistors but I have no idea about the whole circuit, what goes where. I don't have a power source yet but best thing would be to use USB from PC, if it would suffice.

LEDs need to be driven from an Arduino UNO which decides what color and luminosity to display; this is going to be some kind of semaphore on my desk.

I know the question is a bit broad but worth a shot. Any help would be really appreciated.


texts: Selecting RC filter components for half wave rectifier

texts:
I have a circuit where Input is a Sine pulse of 40V Amplitude and the circuit is as shown:

After redtifier diode , there is a RC FILTER. I have used a tantalum capacitor and 0603 resistor. I was wondering if the size of the resistor is OK or i have to increase it for proper heat dissipation. After the filter, the output goes through a voltage divider into ADC input.


texts: Backup power supply using capacitors to help esp8266 run for 3-4 seconds after power failure

texts:
I need to make a circuit with introduction of capacitors in parallel with input supply of esp8266(3.3Vdc) to run it extra 3-4 secs after power failure,

Is it possible to gain extra 3-4 secs just using capacitors or any more components in circuit would be needed?

I want to use just capacitors or some basic components because I don't want to buy any readymade circuit and also it will be cost effective.

Note: I am a programmer so it would be great that I get values of the required components also and circuit diagram if possible!


texts: IEC 61952 Clause 11.1 Electrical Type Test

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Where can I find the acceptance criteria for the Electrical Type Tests? Specifically, where is the Dry lightning impulse withstand voltage test and the Wet power-frequency test in the IEC 61952 Ed 2.0 standard?

Ed 1.0 of IEC 61952 at least pointed you to IEC 60383-1 for these two type tests which had the acceptance criteria there.

Thanks.


texts: Using ISERDESE2 for maximum data rate of 640Mbps

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I want to deserialize data out of a LM98640 which data rate is configurable from 40 Mbps to 640 Mbps, i will use an FPGA of series 7.
But looking at the datasheets i don't know which frequency parameter to look for to choose the right FPGA.
Frequency of BUFG? or the PLL? MMCM?


texts:
I'm from math.stackexchange and I wanted to know the name of an operation on multiple variables. I thgouth what I wanted was the XOR gate, but this is not the case. When I looked on this site I noticed the XOR truth table was this:

\begin{matrix} FFF & 0 \\ FFT & 1 \\ FTF & 1 \\ FTT & 0 \\ TFF & 1 \\ TFT & 0 \\ TTF & 0 \\ TTT & 1  \end{matrix} I would have excpeted, and what I'm after is, this \begin{matrix} FFF & 0 \\ FFT & 1 \\ FTF & 1 \\ FTT & 0 \\ TFF & 1 \\ TFT & 0 \\ TTF & 0 \\ TTT & 0  \end{matrix}

Is there a name for this second table as that is what I would like to use and I would like to stick to convention. Thanks in advance, Ben


texts: If single phase supply can not create rotating MMF, how does Induction motor generate torque?

texts:
I do understand that in a Three phase Motor, a rotating magnetic field is produced in stator and the induced magnetic field in rotor tries to aligns itself with the stator field which makes the rotor rotate.

But in case of a single phase supply, there is only a pulsating stator field. So to start the motor, an auxiliary winding is used which has a field that lags the main field by 90 degrees.

After the motor starts, the auxiliary winding is disconnected and now we only have the pulsating field in stator which can not generate any torque. Then how does the motor continues to produce torque and rotates?