texts: What is the effect of operating an electrolytic capacitor beyond the rated temperature?

texts: I know that the life expectancy of an electrolytic capacitor doubles by 10 degrees decrease in ambient temperature. Is this rule applicable when working beyond the rated temperature or maximum category temperature or not?


texts: BJT transistor junctions: base-collector

texts:
I've been playing with voltage swings in a basic emitter-follower circuit.  If I swing the input too large in the negative cycle, the base-emitter junction is reverse-biased and the transister goes into cutoff mode.  I can see the clipping in the output and this makes sense to me.  With the collector, however, I've noticed that I can swing higher and not see symmetrcial clipping.  Eventually I do see the clipping.

Is there a rule of thumb, like with the base-emitter junction, for managing base-collector junction?  May I use VC-VB=0.6/0.7 V for this relationship too?


texts: Is there an equation or even a graph I can look at that appropriates the % full of an alkaline battery?


texts: What can you do with an Arduino using no extra components?

texts: What projects can be made with an Arduino using a minimum of extra components save what can be found around the house?


texts:
This question is somewhat modified from the original which was asked by someone else. Note that there is more to this than meets the eye. The OP07 or OP070xxx is a 30+ year old op amp, the transistor is PNP (valid but unusual) and the transistor is driven in a way which must saturate any normal device AND has 10x as much base current as collector current. join the dots and see if the real question can be adduced for a beginner who does not realise the unusualness of what they have got:

I have 5v coming in on two resistor going into a transistor.

Second problem 3 voltages coming into a op amp whats the voltage at the nodes, do I add them? I'm having some problem figuring out these two circuits.

http://www.flickr.com/photos/79124850@N08/6931030190/in/photostream
http://www.flickr.com/photos/79124850@N08/6931030192/in/photostream


texts: QUARTUS II: Error: Port "cg" does not exist in macro function "ADD0"

texts:
So i got 8 error while compiling this 4 bit Carry-lookahead adder. I got the above error for ports cg and cp in macro functions ADD0-ADD3. For my code check the attachments. Edit: Here i've copied the code in:

library IEEE;
use IEEE.std_logic_1164.all;

entity cla4 is -- 4-bit CLA structural model: top entity
port(
    a, b                  : in std_logic_vector(3 downto 0);
    carryin               : in std_logic;
    sum, ch, cq           : out std_logic_vector(3 downto 0);
    cgout, cpout, overflow: out std_logic);
end cla4;

architecture arch of cla4 is
    component fagp -- component declaration
    port(
        a, b, cin   : in std_logic;
        sum, cg, cp : out std_logic);
    end component;

    component cla_logic -- component declaration CLA-generator
    port(
        g, p          : in std_logic_vector(3 downto 0);
        cin           : in std_logic;
        c             : out std_logic_vector(2 downto 0);
        cgout, cpout  : out std_logic);
    end component;

    signal carry  : std_logic_vector(3 downto 0); --local signals
    signal cg, cp : std_logic_vector(3 downto 0);
    signal cout   : std_logic;

begin
        carry(0) <= carryin;

        ADD0: fagp
        port map (a(0), b(0), carry(0), sum(0), cg(0), cp(0));

        ADD1: fagp
        port map (a(1), b(1), carry(1), sum(1), cg(1), cp(1));

        ADD2: fagp
        port map (a(2), b(2), carry(2), sum(2), cg(2), cp(2));

        ADD3: fagp
        port map (a(3), b(3), carry(3), sum(3), cg(3), cp(3));

        --generate carries from
        --propagate and generate values
        --from full_adder_g_p_g_p
        CLA: cla_logic
        port map(cg, cp, carryin, carry(3 downto 1), cout, cpout);

        cgout <= cout;
        overflow <= carry(3) xor cout;
end arch;

cla_logic:

library IEEE;
use IEEE.std_logic_1164.all;

entity cla_logic is
port(
    G, P         : in std_logic_vector(3 downto 0);
    CIN          : in std_logic;
    C            : out std_logic_vector(2 downto 0); -- “internal” carry
    CGOUT, CPOUT : out std_logic);
end cla_logic;

architecture arch of cla_logic is
begin
    C(0) <= G(0) or (P(0) and CIN);
    C(1) <= G(1) or (G(0) and P(1)) or (CIN and P(0) and P(1));
    C(2) <= G(2) or (G(1) and P(2)) or (G(0) and P(1) and P(2)) or (CIN and P(0) and P(1) and P(2));
    CGOUT<= G(3) or (G(2) and P(3)) or (G(0) and P(2) and P(3)) or (G(0) and P(1) and P(2) and P(3)) or (CIN and P(0) and P(1) and P(2) and P(3));
    CPOUT<= (P(3) and P(2) and P(1) and P(0));
end arch;

fagp:

library IEEE;
use IEEE.std_logic_1164.all;

entity fagp is
port(
    a, b, cin : in std_logic;
    sum, g, p : out std_logic);
end fagp;

architecture arch of fagp is
begin
    sum <= a xor b xor cin;
    p <= a and b; --complete this
    g <= a or b; --complete this
end arch;

Any ideas??


texts: How does at low power factor impedance (p.f=R/Z) (if R is constant ) increases while current also increases?

texts:
Impedance is equivalent resistance of circuit having resistive and reactive components so if we keep R constant and increase inductance than Z will increase and power factor will going to decrease as power factor can also be stated as ratio of R and Z. (R/Z)
 So here comes a contradiction that increasing impedance increasing the current.


texts:
I have two AGM batteries that I was wondering if I'm charging them correctly.
They are 12v, 7ah batteries rated for 2a.
I use a CC/CV power supply to charge them at constant current of 1.5 amps until the voltage reaches 13.8v, then I switch to constant voltage and continue charging until the current drops to about 0.1 amps. This takes anywhere from 15 minutes to a few hours, depending on how much battery I used.
Then, I take them off the charger and let them sit and balance out for an hour or two, and once their voltage reaches about 13.3v, then I start using them.
I haven't had this happen yet, but I will recharge the battery once its non-loaded voltage drops to 12.2v or lower.
Am I doing it right?


texts: Zener Diode: Easing the load on a regulator

texts:
Summary: I am using a LM317 to drive a liquid pump that draws 1A. Unfortunately my regulator is dissipating way too much power and getting too hot. Currently my input voltage to the regulator is 12V and I'm trying to create 7V so that's 5Watts! So I bought a heat sink BUT I would also like to drop the input voltage of the regulator a little lower, no need for it to be 12V.

Goal: To drop the 12V input voltage to around 9V for the regulator by using a zener diode, that way the power dissipation is lowered to about 2W.

Question:
1) Could I get a sanity check on my circuit I created?
2) Do I need to worry about the current going through the zener diode because its 1A?
3) Could I just use a 3.3ohm resistor instead of a zener diode at all that way 3.3ohmd*1A is 3.3V drop which should do the same thing.


texts: How to increase torque and decrease RPM of a DC motor?

texts: The motor is an old one from a cassete player of some sort. I am powering the motor with a 9 volt battery, but it's RPM is too high for the desired purpose. I have used gears to reduce RPM but it is still too high. I don't think I can increase the gear ratio anymore. Can you suggest a way to decrease the RPM further and increase the torque (if possible). Please suggest a circuit to accomplish it.


texts: A Battery Charger which can extend LEAD ACID Battery life

texts:
I am making a battery charger for a 45AH LEAD Acid Car Battery. That I will use with 100 W (1 A 100 V AC) UPS.

I need to know that what things I should keep in mind so that the battery charger charge the battery efficiently so as to extend its life.
For now I only have this hint that a charger should stop charging the battery after it is fully charged.

What are the other features of a charger which extend battery life?


texts:
I'm finding it difficult to understand how to read this optoisolator documentation.

Here is the optoisolator: http://html.alldatasheet.com/html-pdf/92367/TOSHIBA/TLP222A-2/248/1/TLP222A-2.html

The triggering device is an Arduino is an UNO (5v up to 40ma per pin).

My first configuration was UNO GND --> 220ohm resistor --> opto Anode --> opto cathode --> UNO pin 12.  (Didn't work)

After that I tried removing the resistor, that didn't work either.

I'm guessing either my configuration is backwards, or I'm not using the correct resistor. If anyone could help me better understand how to parse the documentation, It would be greatly appreciated!

edit1:
here is a photo of the configuration. There is an input on pin 13 which works fine, but the output on pin 12 (opto-isolator) does not. I can measure 5 volts with a multimeter but the opto-isolator does not short the drains.

resistor is rrbg (220 ohm 5%)


texts: SMD Crystal solder(?) problem and any recommended test procedure

texts:
I use a 32.768 kHz SMD crystal (datasheet) for a MCU. Here is the layout part of the crystal.

Here is a view from an actual PCB

I mounted the components by hand-soldering, and produced about 30 modules.

Most modules' crystal didn't start working at the beginning, but I solved it by re-soldering the crystal by applying a little bit more solder under it. The interesting thing is that when I touch a pin of the crystal by a tweezers, the crystal starts working. Here is an an oscilloscope view of the crystal's signal.

The glitch is where I touched the path by a tweezers, and then the oscillation starts.

Another fact is that some of board's crystal work if I touch to the C451 cap's path, some of them start working if I touch to C441 cap's path (e.g., if it works by touching the C451 cap's path, it does not work if I touch to C441 cap's path).

This made me doubt if it is related with the solder under the crystal (maybe uneven contact surface or another reason that I can't think of). Or if it is not a purely solder related problem, as I sometimes needed to perform re-soldering process several times till the crystal problem is solved. On the above PCB view, the extra solder sticks out from side of the crystal (no short circuit to another pad or case of the crystal), there should be for sure a connection between the crystal's pin and the PCB pad, but the problem still remains.

Another issue is that I experienced on 4 boards that they work after I re-apply solder under them, but when I test them the next day, the crystal has the same issue.

Question.1 Has anyone experienced similar problem or could think of what could be the actual problem?

Question.2 The boards will be on the field, I have a concern that they will work here but have problem when the customer needs to use them. How I test them is to start the modules couples times at a day and observe if there is any failure and spread this test to a week long. Is there any method/technique to test (or get indication) if the crystal will probably work fine in the near feature

I inspected the PCBs by a microscope that there is no short circuit between any trace or there is no any solder connection from the case of the crystal to any path
On the problematic boards, I re-placed the crystal with the ones that I removed from the board that works OK, therefore it should not be a component problem
I cleaned the flux residues on PCB but it does not change the result
I did search if there is a special procedure/technique to solder such type of SMD crystals but couldn't find any related information.

EDIT
I tried placing a different capacitor values but didn't help.

EDIT2
Here is the gerber view of the reference design of TI, as it is an optional crystal, it is connected through 0 ohm resistors(R451, R441)


texts: What is the expected delay on a dali ballast from actioning a Direct Arc Power command

texts:
I am sending toggling Direct arc power commands to a LED driver. ( OFF / ON ) at an equal interval of 500mS.
I am monitoring the dali bus commands with a Lunatone USB interface and I can see that the Led driver sometimes missed the ON - interestingly it never missed the off command.
The interval between commands was then extended to 1500mS.
This then showed that there it was not missing the command but in fact a notable delay happening occasionaly with the ON command.

There is only the one Dali device on the bus.
I'm wondering what the specification is for this.

Edit: Looking at the Dali Specification ( Standards titles ONLY )
What is the difference between :
1) BS EN 62386-102:2014  CONTROL GEAR
2) BS EN 62386-103:2014  CONTROL DEVICES

(one wonders why they would not be in the same standard as probably much is duplicated)


texts: EAGLE: Add a GND bus and a VCC bus to a proto board

texts:
I am quite new in the Eagle world and I need help.
I have made a bunch of simple prototyping PCBs of different sizes as part of a custom library and now I want to add a GND bus and a VCC bus (like in the photo below).

I have done some research and I have found this project:

enter link description here

in which this guy is just using the routing command for connecting the holes in the GND bus. But I still have a couple of questions:
1) Is this the best way for solving my issue?
2) It is possibile to do the routing directly in the library editor or I must do this in a new project?
3) Is there any difference between a route on the bottom layer or in the top layer for a 2 layers PCB?

Thank you for your time!


texts: Inductor and Capacitor for Bidirectional DC-DC Converter with Battery

texts:
I have to design a bidirectional converter to regulate a DC bus at 250 V with a battery bank at 144 V. My question is how to do it optimally, because I do not know the maximum ripple allowed in the current of the inductor to not damage the battery, I also do not know what would be the ideal switching frequency for this type of application. Anyone with experience in the field could give me some tips?

First of all I already have the closed loop control for the converter. My problem is not the operation, I can control the voltage, but I have doubts if it is correct to subject the battery to high current frequency variations as is happening. Below I show how I designed the parameters of the converter, as I did just for the boost, since according to the principle of power conservation the components must be the same for bust, changing only the switching of the IGBTs. I'm not sure if this is true, I do not know if it's what happens in real life for the application I'm doing, I need a lot of tips and references for it, not is the type of information found in papers or books.

Parameters

Rated Power = 10kW
Rated Voltage = 250 V
Vbattery = 144 V

Fsw = 25kHz

Ripple Voltage in capacitor = 0.1%
Ripple Current in Inductor (That's my doubt) = 20%

ΔiL = 13.8889

Lmin = 1.7584e-05

L (considering the ΔiL) = 1.7584e-04

C = 0.0027

These are the values calculated on the basis of the specifications that I have dubiously determined.

Objetive

The purpose of applying this converter together with batteries is to regulate the voltage in a DC bus that varies in a random manner.

I have some power electronics books, but most of them are very straightforward with respect to calculations and provide little theoretical information about converter designs. I would like someone's opinion on the converter specifications for this type of application, and if possible some bibliographical references.

Circuit and Results

Simulink Circuit

The plots below show the CURRENT (TOP) and VOLTAGE(DONW) in differents scales

Result with a zoom out

Result with zoom

More closely

So I posted all my project and the results in different scales, can someone please help me ?


texts: Purpose of input resistor in ADC circuit

texts:
What is the implication of the 1 Megaohm resistor in the schematics attached? Will I be able to detect the condition of the motor (running, not running, stalled)?

Part information:

MCU ADC (ADC type: SAR) leakage current is 1uA.
R3 (Load) is a H bridge (pair of PNPs (5CS) and NPNs(6CS)).
Motor type is DC brush-less with following current rating:
Normal Load Current (Running) - 80 mA
Stall Current - 200 mA

simulate this circuit – Schematic created using CircuitLab


texts:
I had some hard time soldering new switches to my computer mouse, now it looks like I lost some solder pads, what shouild I do? Every other component of the PCB seems ok cuz I didnt touch it.
Photos:


texts: I'm replacing a 24VAC transformer that supplies power to a motorized skylight

texts:
I could use some help selecting a replacement transformer with the correct amps. The transformer supplies power to a PCB that switches a small low-speed hi-torque motor via a battery operated remote control to lift and shut the skylight. The skylight weighs about 40 lbs max.

The local electronic supply store couldn't identify the transformer and couldn't give me any more info.

After much googling and multiple calls to the manufacturer, the only information I have been able to find about the motor and transformer are as follows:

Transformer: 120VAC in, 24VAC out, Class 2.
Motor: 60W, 60Hz.

Without knowing the exact load requirement of the motor, do you foresee any problem using a 40VA 24VAC transformer with say 2.5 amps?

Thanks.


texts:
l want to build something like this. l am not sure how  and if is possible to connect because as it shows rj-45 image

has more pins than ft232rl chip

DSR (Data Set Ready)

RTS (Request To Send) is missing. Are these pins required for this conversion ?


texts: How to use different 7-segment for different numbers in FPGA board?

texts:
I'm working working with NEXYS4DDR board which has two 4-digit 7 segment displays. Using the proper binary-bcd converter I can display numbers, the problem is... the same number is displayed in all the displays (assuming all are activated), like: 1 1 1 1 1 1 1 1 because I can only control one set of segments (CA, CB, CD, CE, CF, CG) and not one set of segments for each display. How can I separate them? To show, like 1 2 3 4? A SystemVerilog or Verilog solution would be preferred since that's the HDL I'm currently learning.

For reference, the board is: https://reference.digilentinc.com/reference/programmable-logic/nexys-4-ddr/start


texts: 0.1 uF in parallel with larger >1 uF to reduce noise from IC

texts:
Back in the day when we would use an electrolytic capacitor across the supply of a IC we would always put a 100nf Ceramic in parallel because (if I remember correctly) electrolytics had inherent inductive properties that would not suppress the HF noise on the power rails.
However, these days, high value ceramics exist (I regularly use 47 uF SMD in an 0805 package).
So does this mean, that I can get rid of the 100 nF (Ceramic) in parallel with the 47 uF (ceramic) caps because the 47 uF is ceramic and hence does not have the inductive properties of the electrolytics?
thanks


texts: How to compare performace of EMG electrodes?

texts:
I'm working on building an acquisition system for sEMG signals. The problem I'm facing is how can I reliably measure the performance of different designs? Obviously I can just put the electrodes to my arm and see the signals on the oscilloscope, but that's not very objective way. The quality of signal can be affected by things like:

position of the electrode on the muscle
amount of sweat on the skin
how strongly I contract the muscles
muscle fatigue

I would like to have some sort of artificial muscle that I could attach the electrodes to, and that would always generate the same, repeatable signal. How can I do it?
For testing stuff like filtering software and hardware I can solder wires in place of electrode plates and connect them to signal generator, but I would like to do the end-to-end testing of the complete system.
Picture of electrode for reference:


texts:
I plan to have three 50 watt, 12V LEDS, 3750mA wired in parallel.  I would like to have an individual switch for each light.
What amp rating switch would I need for each light.  I wasn't sure if I need to factor the Ah of the battery or just account for the 3750mA the light demands (or is it the combined amps of all lights?) Sorry, learning here obviously.
Resistors aside, I would assume I would run the neutral from the LED to the battery and interrupt the Hot wire with the switch?


texts: Determining if a power supply is isolated?

texts:
I've been looking for a low cost adapter I can use to power some electronic circuits I'm playing with. Pretty much the only requirement I have at this time is that the adapter is mains isolated for my safety. However, I can't find any markings on the adapters I have or any adapters I've found online which would indicate if the adapter is mains isolated.

Is there a way to determine if an AC-DC wall adapter is isolated from mains, preferably without taking it apart, or are they all isolated and I'm making a large fuss over nothing?

A few different specific examples I had in mind:

A cell phone USB charger
Advertised as Linear unregulated AC-DC supply
Advertised as a switch mode AC-DC supply
A laptop power brick
Advertised as a regulated supply (no indication if switch-mode or linear)


texts: Calculate the Thermal Resistance (Junction to ambient) from Thermal Resistance (Junction to mounting base)

texts:
I have this MOSFET - MOSFET Datasheet
I want to calculate the maximum junction temperature of the MOSFET part. I have calculated the power dissipation.
In the MOSFET datasheet, there is only Thermal Resistance (junction to mounting base) parameter is only given. Junction to Ambient thermal resistance is absent.
How to approach or calculate the value for thermal resistance junction to ambient from junction to mounting base value?
I have tried to look in the manufacturers website but couldn't find better documents that can help me.
Supporting documents - LFPAK Thermal Design Guide
Part Information
Please help to find the thermal resistance junction to ambient value


texts: thermal glue or paste thermal resistance

texts:
Trying to calculate thermal resistance before heat sink for cooling MOSFET.
MOSFET Rjc is given in datasheet. But heat sink will be glued using thermal glue like HC910 which has thermal conductivity of 1.7 W/m*K

I need to calculate Thermal resistance of glue layer.

So,

Rglue=THICKNESS / ( AREA * K)

K- thermal conductivity

I my case area is 0.01m*0.009m=0,0000054  sq.m
K is 1.7
And i have no clue what thickness will be. I took 0.1mm as a wild guess.
I know that thermal paste (like artic silver usually go 0.01-0.02mm, but glue
is thicker.

So, in my case Rglue = 0.53 K/W

Is my logic correct? Any idea about thickness?


texts: NPN SMT Transistor with flipped Emitter and Collector

texts:
Good day!

I have designed a little circuit and got some (5) PCBs printed and assembled in china and unfortunately I made a mistake when I transferred my prototype circuit into my schematic. Even less fortunate I only realized that mistake after I tried to test the boards at home, not before I ordered them.

I have the following subpart of a schematic:

I mistakenly confused the emitter and collector here. The INP should go into the collector and DT into the emitter.

since I already have some readily printed and assembled boards here this poses a challenge to me. I don't want to spend another 140 bucks for a minor mistake (and I'm not even sure if I didn't make another mistake here).

On one board I already removed the transistor. I only have normal, let's call it breadboard sized transistors at home. I tried to bend one's (TIP120 - Not the correct specs but worth a short try if it's feasible at all) connectors into the correct pinout positions and solder it to the board with more flexible wires in between, but I think my motoric abilities are not sufficient enough for that kind of task (don't know if you can grasp the tiny dimensions from that picture, but it's super small).

A second idea was to find a transistor that has its emitter and collector flipped (where the emitter is on the top center and collector is on the bottom left). I thought of a PNP transistor but that wouldn't suit my circuit either. As for NPN I couldn't find a suitable replacement for the given transistor and it's form/package (SOT-23).

I want to try a smaller transistor as opposed to the TIP 120 (like the SS8050-TA in TO-92).
In the meantime, does anyone have experience with that and maybe even know a transistor (or type of transistor) that i could search for? I would also be happy to try different approaches to solve that problem.

Thank you very much for your help!

** EDIT **

for completeness and to make it easier to read in future I tried to visualize the pin situation.

BLUE is the correct transistor SOT-23 pin out
RED is my faulty connection, aka how the transistor should be connected., resulting into the flipping of C and E, indicated by the blue arrow


texts: Which controller board is best for hooking up rasberry pi to Traxxas 5675 Titan 77?

texts:
Can I hook this motor up to my rasberry pi?: http://www.amazon.com/Traxxas-7075-Titan-Brushless-Motor/dp/B0027GGZYU/ref=pd_sbs_t_4

How about this one?
http://www.amazon.com/Traxxas-Titan-Motor-10-Turn-Volts/dp/B001SETT0Y/ref=sr_1_2?ie=UTF8&qid=1383160714&sr=8-2&keywords=traxxas+titan

What would be the best controller board to use?

What stops this from being hooked up directly to the pi? Is it only voltage? I suspect a controller is needed for precision speed control.


texts: How do pick and place machines pick up components?

texts: I first thought they used a vacuum of air so they don't dislodge the components after they've placed them?


texts:
My PCB requires a mounting slot connected to the ground. I know how to use grounded mounting holes, but I can't figure out how to produce the desired result using a single slot. Is there a component in some library that I could use? Or do I need to define the shapes using the Pad (17) and Milling (46) layer? If so, how should I set up the shapes so that the fab house understands that the slots are to be plated?

This image shows what I can do:

This edited image shows what I would like to achieve:


texts:
I am yet another software developer trying to step into the world of electronics... (so sorry for the basic questions...)

I am trying to understand how a capacitor works, but obviously I am missing a crucial part from all the helpful websites like sparkfun and adafruit.

I failed to solve an issue I currently have in a pretty basic project that reads a temperature from a thermocouple and displays the value on an LCD. An electrical engineer at work pointed me in the direction of adding a capacitor to filter the noise I introduce when I touch the thermocouple. Long story short; the capacitor doesn't seem to charge, no matter how I add the capacitor to the circuit, almost no voltage comes out; ever.

So I thought to be smart, and make a new circuit of:

a battery supply (9.6V)
an LED
a capacitor "104"

The circuit is simple, all components are in series, so I expected that my LED would light up, and when I disconnect the battery, the LED would fade out. But again... nothing happens. The LED never lights up, and my multi meter measures 0.8V after the capacitor. But also, when I hold the multimeter probes to the leg of the capacitor, the measured voltage drops from 0.8V to close to zero in no time.

Please forgive me if this drawing is wrong (and please do tell me what is wrong so that I can learn from it):

Why doesn't the capacitor charge up to the voltage of 9V (but seem to stop charging at 0.8V?)?
Why does it discharge when I measure the voltage with a multi meter?

PS: there is no resistor between in the circuit limiting the current, and the batteries are 8x 1.2V rechargeables = 9.6V


texts: Scaling a car's injector pulses to count and time them?

texts:
What would be an efficient way to reshape a car's injector pulses to digital 0-3.3V pulses, so a microcontroller can count and time them? The waveform can be seen on this page under "Example waveform".

This question might be considered a duplicate of Efficient spike detecting Microprocessor or DSP architecture but none of the answers is really clear for me. I wonder if the transistor solution works with Vb >> Vc. The flip-flop solution misses the voltage scaling stage.

Requirements:

the circuit must present a high impedance to the coil (arbitrarily set at > 1Meg)
must correctly detect pulses between 5 and 150Hz
should survive common faults (wire disconnected and reversed polarity)

Assumptions:

voltage spike amplitude is not constant, and can go anywhere from 30V to 120V (again, somewhat arbitrary).
voltage spike duration is not constant, and can go anywhere from 200us to 4ms (again).
Processor is likely to be an Atmel SAM D20 or D21 (3.3V).
Supplies available: automotive 12V, not regulated; 5V, regulated, 3.3V, regulated.
the microcontroller has edge-triggered interrupts and input-capture mechanisms

A solution based on the signal levels instead of the spikes could also be acceptable, assuming that it works with a high voltage anywhere between 9 and 16V.

One simple solution would be a 1Meg resistor in series and a 3.3V zener (or even a 3V one, or maybe a shottky diode to Vcc), but the high-value resistor (and thus low current) means that we're in an area that is often overlooked in diode datasheets. In a previous case, I had conduction in an IC's protection diodes, causing incorrect behavior in other parts of the IC. I'd like to make sure that this doesn't happen. I'm also not sure whether the input-compare can deal correctly with such an high input impedance.

Thanks


texts:
I want an alternative low component, transformerless power supply for low power DC projects, I have used Shunt Regulators in the past but never with AC. Below I have proposed a AC to DC shunt type regulator using a Constant current diode (AL5890) to limit the current to 40ma and a 5v6 Zener to regulate the voltage to 5v. the input voltage is 230VAC,

Would it be a good idea to still use a current limiting resistor in addition to the Constant current diode?
How reliable would this setup be ?


texts: What happens if I connect a low voltage rated capacitor to a high voltage?

texts: Given that c=q/v even if I connect it to a higher V, its charge Q may decrease proportionally right? So why should it damage my capacitor? or will the internal electric field get too high and cause the dielectric to break down? Or would it just get too leaky and then overheat due to greatly increased self heating?


texts: Problem with switching solenoid valve by relay

texts:
I've been trying to drive a 12volt solenoidal valve with a 5volt relay .Relay is working perfectly for driving normal loads(light bulbs).But it is not driving my 12volt solenoidal valve.
I've already connected a fly back protection diode across solenoidal valve.
My circuit almost looks like these....

The source used is 12volt not 24 and dashed box is a microcontroller circuit .Sorry for not including these.


texts: STM32/STM8: How do I come from evaluation board to my design?

texts:
I'm a kind of a newbie to STM32/STM8 controllers. All my experience was with 8051, PIC and AVR controllers. And the typical development chain was like this:

Make PCB
Debug this PCB with my program.

Nowadays there are many of convenient development tools available.

So if I make and debug my program on any STM evaluation board (discovery, nucleo and so on). What should I do next?

I can make my own PCB with the same controller and the same pin assignment. Can I use exactly the same .BIN file to load it to my board through SWD (SWIM) interface?

What if I need to take slightly different controller? Or use another pins?

If I search Stack Exchange for the answer I will find this question with particulary this answer.

Which state (looks like) that this should be fine. However, what if I change the controller or pin assignment? Is the same thing can be applied to STM8 series?

Another one thing is what come in the controller from the manufacturer? Is there any bootloader in the flash or something?


texts: Multiple Direct Digital Synthesizers (DDS) to Increase Sample Rate

texts:
I’m looking to generate a RF signal sampled at around 10 GSPS operating above the 3GHz mark. In order to maximize data throughput, the signal will be modulated at that frequency (rather than mixing in a lower frequency baseband).
I have a working system at around 2.5 GSPS using a single AD9915, the parallel input of which is driven using an FPGA (which defines the desired DDS output for each sample on each clock cycle). The AD9915 allows synchronization of output across multiple ICs with a maximum sample rate of 2.5 GSPS.
I’m looking at the most cost efficient possibilities to get to a sample rate closer to 10 GSPS with at least 12-bit resolution (less is not an option). Firstly I’d be open to any IC which can already do this, I haven’t found one. Secondly I have another proposal to do this which would require a different type of multiplexing IC for which I’m not sure one exists...
The idea is to synchronize multiple AD9915s (supported, P34 of datasheet), independently drive their parallel inputs for modulation using an FPGA and then use some kind of very high speed ‘analog multiplexer?’ to sample each AD9915 independently to create a higher resolution output. The theory of operation is shown below, but the question is whether anyone is aware of an IC which can accomplish multiplexing these signals at these speeds while maintaining sync?
Illustration of Multiplexing Idea to increase sample rate:

Note: the above diagram shows using two AD9915s, I’m looking to use four but the same theory would apply.
Notice the the multiplexed output (lower chart) is at twice the resolution of the first due to the multiplexer running at 5 GHZ (GSPS).
I’m open to solutions to get the sample rate up. Perhaps another way to think about this problem is creating an arbitrary waveform generator. Most high-end OEMs seem to use custom silicon, this isn't an option for me due to low volume and a commensurately small budget.
Does anyone know how I could create the combined waveform (in the diagram) reliably at the sample rates specified, or does anyone know of any other solution which would get closer to 10 GSPS?
Footnote 1: I’m not looking for bench equipment, I’m looking to incorporate this into a relatively small device with control over how it is designed and produced.
Footnote 2: I’m aware that the AD9914 can go to 3.5 GSPS, but it only supports synchronization across ICs at 2.5 GSPS, and I’d like to get above 3.5 GSPS.


texts:
I have a 5V stepper motor with a 1/64 gear reduction; it looks like this:

When at rest, I can't turn the shaft with my fingers. However, when the shaft turns, I can. It seems that the torque is lower when it's turning - how come this is the case? Isn't torque dependent on the gear reduction irrespective of the shaft's motion?


texts: Need an XOR gate that works up to 2 to 3 GHz

texts:
I have encountered an unusual situation in which I require an XOR gate that will function reliably when presented with a square wave input with a frequency between 2 and 3 GHz. I know that desktop CPUs have logic gates that can function at these speeds, but I don't know of any IC that will do this. Should I try to build the gate out of transistors?

Also, at these speeds, do I need to worry about using ground planes, mitered bends, and microstrip?


texts: I'm boosting an LM7805 to 16V using Zener diodes in series at the GND pin (pin 2) of the 7805. The Zener Diodes I'm using are 1 of each of the following: 3.3V, 3.0V, and a 4.7V. Now theoretically I should be getting 16.0V out (3.3+3.0+4.7+5.0) but for some reason the most I've gotten is only 10V. All these zeners are brand new and I have them oriented properly with the cathode connected to pin 2 of the 7805 and the anode to ground of my input. The reason why I have so many diodes is to power other parts of the circuit like how you'd tap off of resistors in a voltage divider for its divided power. So is there something else that I should've added and that's why I don't have a full 16.0V out or am I doing something wrong?


texts: How to choose equivalent transistors for replacement

texts:
I'm working on replacing some power transistors in an old power supply. One of the transistors that I need to replace is an old MJ900 pnp power transistor with a newer close to equivalent one since it's hard to find the originals and or expensive. The power supply was made in the early 1970s.

What are some key concepts when choosing equivalent parts? What parameters are important to match, no so important, and not important at all?


texts: Frequency of output of full-wave rectifier

texts:
Frequency of output voltage of full-wave rectifier is twice of
  frequency of its input voltage.

This is what I read in a book but don't know how to prove it.Please explain


texts: I'm looking for open source, simple (simple enough for arduino, for example) protocol for transfer of some messages over audio (eg. in the apartment environment, not by analog line, but between speaker and mic, via air). It should be noise resistant and not binary (not Morse) - it's a art project, the idea is to make controllers to communicate like r2d2's


texts: How to turn a motor while obtaining the angle it turned?

texts:
I need a device where it can turn mechanically, while be able to measure the angle of which the motor turned.
One solution I thought about was to connect the motor with potentiometer.

However, is there any devices that could do the similar job? It's a control circuit, so it doesn't need to turn fast.


texts:
I looked for days trying to find datasheet to this component. I concluded that this is a Quad Flat No-lead. But trying to search the marking code gets me nowhere. I did however find couple websites selling it, but it looked to me it's a scam. Pay now and never see your product. No contact information.

Also, I found some datasheet for an QFN32, but comparing what the pins do is different. And that's where I am stuck.

This chip is from a gps that won't turn on. I believe that it's making a noise and that might be the problem.

I am asking if someone know anything about this chip and what would be the equivalent replacement some that I can study its data to farther trouble shoot it.
I appreciate any comments and answers.


texts: power supply cut-off in umbilical power cord to tube amp

texts:
I am building a tube amp with a separate power supply in a second enclosure - connected to the amp via an umbilical power cord.

What is the most elegant way to keep the power supply off if someone inadvertently turned on the power supply without the umbilical cord being plugged into the amp?

I have heard of using a relay to do this by running an additional ground wire in the umbilical cord, but haven't seen a schematic or any details of how this would actually be done.

This is a hi-fi amp with a Edcor xpwr054-120 TRANSFORMER, so I will use it for the heater power @24 VDC and the main power @330 VDC (power supply takes the 240 VDC and ramps it to needed 330).

I guess I don't have a way to run an additional low voltage signal via a relay with this setup, is that true? Any suggestions?


texts: Choosing Oscilloscope with appropriate bandwidth for Jitter analysis

texts: Can someone give me a rule of thumb of choosing Oscilloscope with appropriate bandwidth for the Jitter analysis of clock signals? What device is highly preferable: spectrum analyzers, frequency counters, real time scopes Or Sampling scope with clock recovery?? Which is highly preferable of getting accurate jitters measurements? I need to measure between 10 Mhz - 10 Ghz signals?


texts:
I am trying to experiment with WWVB receiver design...

The antenna I am using is from another WWVB receiver module.  It is a loop antenna with a capacitor that I assume is tuned to 60kHz.

Questions-

When I a probe the antenna with the Oscilloscope I don't see the ON/OFF 60k signal I expect. It looks more like a bunch of noise.
When I connect the antenna to an emitter follower it changes the signal. Could the decoupling capacitor be effecting the antenna's tuned frequency?


texts: Why ATMEGA328P U-TH doesn't answer to USBasp but work fine with Arduino as ISP?

texts:
I ordered ATMEGA328P AU from China recently but I got "ATMEGA328P U-TH". which seem super problematic.
I try to use USBasp to burn bootloader but it fail and show error message as shown.
avrdude: error: program enable: target doesn't answer. 1
avrdude: initialization failed, rc=-1
     Double check connections and try again, or use -F to override
     this check.

which I believed many people face same situation as mine. Then I accidentally found the solution by using Arduino as ISP which successfully burn bootloader. After that I can use USBasp to upload sketch or burn bootloader.  I don't understand what happen here.
Note: I solder ATMEGA328P U-TH in SMD package to Arduino UNO clone.


texts: How do you determine the direction of AC current? (ex: whether your solar-powered house is drawing from the city power grid or adding to the grid)

texts:
I'd like to measure the voltage and current of mains AC power at the fuse box where a house is connected to the grid. Assuming the house has solar panels on it, sometimes it will draw from the grid, and sometimes it will push to the grid. How can I measure the direction of AC current to determine which it is doing?
I plan on using a microcontroller to sample the AC waveform and do whatever math or RMS calculations I need to do once I understand what I need to do.


texts:
I had a 7 segment, 4 digit display hooked to a very large board with et6226m (similar to tm1650), so i decided to desolder and pack it by putting the driver in between the 12 pins of display. Tested it and with my mcu, it worked fine but with a twist and thats confusing me..

First 3digits work fine, i can write 8 on them but if i try to write 8 on 4th digit, display starts to malfunction (flickers, turnsoff etc).

I can however write 9 on the last (4th) digit, which means only one out of 7 leds on 4th digit have a problem (led E).

I tested it manually with both a multimeter and by applying small voltages (like 2) on pin DIG4 and E, it does light up so its not burnt and neither is there a short circuit.

I don't think i have bad connections given the tests i performed, what could possibly have caused it.(It was working fine before i performed surgery on it).

Notes:

Wires I used were from old headphones, single thread copper wire coated with enamel(?)
everything is hot glued, no risk of short circuits.
i did removed a zenor(?) diode on pin dig4 thinking that it might be the one causing problems.

Update:

Datasheet

Connections

Lashup, You asked for it

Update2: just noticed there were two capacitors connected between vcc and gnd that forgot to put inside my new design, can those missing capacitors cause this problem?

Update3: I rewired everything and problem persists but it does work properly on 3v now (maybe because of longer wires?) which means it have something to do with over-volatage on ic (datasheet says it can work on 5v) or my mcu not being able to provide enough amps to that part only, New Question, Do I need a resistor and/or capacitor in there somewhere? If yes, what should values be?


texts: Multiple buck convertors on one plug/power source

texts:
I have a question in regards to using multiple buck convertors.
I want to use a 12v plug/supply to run one wire to the 12v, two 5volts and one 8volt. What I want to know if it’s possible to have a wire run to the 12v (without buck convertor) and then have separate buck convertors on each of the other powers. I.e one for the 2 5volts ( or have one each) and one for the 8volts. Is that possible. Any help would be very much appreciated. Thanks


texts: Providing RS-485 ground when no pin is provided

texts:
I have a PC with an RS-232 to RS-485 converter controlling (@ 9600 baud) a large piece of HVAC equipment in an adjacent utility room, <50' away.  We are adding two more of these pieces of equipment, each about 10' from the first unit, and would like to add them to the RS-485 bus.  Everything I've read says that using a 3rd ground conductor is mandatory, and that just wiring the differential pair can fry the tranceivers... but the manufacturer of this equipment doesn't even  provide for a signal ground.  RS-485 is connected through a DB9 connector, with only 2 pins (A/B lines) connected.  Note this is an industrial setting, and the equipment is powered through large, 3 phase pin-and-sleeve connectors.  Should I:

Just wire to the two signal lines, assuming ground potential difference isn't an issue at this scale, and/or that the mfg. has taken steps to protect their equipment;
Tie signal ground and shield together at the PC side, and connect the shield to the chassis at the equipment side;
Connect the signal ground to the GND pin in the RS-232 connector the equipment also has, assuming the -232 and -485 transceivers use the same reference;
Something else?

Thank you!


texts:
I was going through SATA3 spec. As per the spec, both scrambler and 8b/10b encoder are used in its design. Scrambler helps randomizing the data while 8b/10 encoder creates enough transition for DC balance and clock data recovery.

My doubt is that if the scrambler randomizes the data, then it should solve the purpose of DC balance and clock data recovery, because transitions of '1' and '0' are being created by the scrambler. What is the need for 8b/10b encoder then?


texts: What's the difference between ON voltage and threshold voltage in FETs?

texts: In field-effect transistors (FETs), what's the difference between ON voltage, \$V_{\text{on}}\$, and threshold voltage, \$V_{\text{T}}\$?


texts:
I’m a total newbie at this and I need some help. I searched on Google and asked all these other sites. I couldn’t find what I was looking for. Well, I have a venom 8.4 V 3000 mAh pack that won’t hold a charge for very long. I examined the pack and I couldn’t find any damage or something noticeable. I would like to learn how to diy (do it myself), but don't want to damage it more or, even worse, injure myself. Please help!!

I’ve looked on this site. Like I said, I'm a newbie and some of the information I found here doesn't make sense to me.


texts:
I've built a PCB using the below circuit.
I'm having some issues when the solenoid is being energized. It seems as if the kickback is getting into the ground plane affecting the PWM signal. Any help/tips on how to clean up this noise will be appreciated.

The solenoid current is about 1.3Amps for first 10ms @ 90% duty cycle then duty cycle drops to 50% for remainder of actuation. Frequency is set at 24Khz.

EDIT 2:
Added a gate resistor (divider R29,R30) at output of U2.
Seems to have reduced the noise issue.

Ch1 on the scope (green) is looking at the voltage across the solenoid connected at J2. Ch2 on the scope (yellow) is looking at the PWM_ON signal coming from the micro at R2. I've added a resistor divider and seems to have helped a little, but still very crappy.

Also maybe Q1 is not fully turning on?

New Waveform with gate resistors.

Old Waveform with no gate resistors.

Yellow is Q2 Gate and Green is voltage across solenoid.


texts:
I have come across an unusual part of a circuit that I hope someone could shed some light on and I have redrawn in LTSPICE. The circuit is to measure voltage of a 3-phase generator. Two of the phases R and S are measured and applied to the rectifier shown below. The "+" and "-" are then fed into a differential amp.
It is unusual to see the second phase applied to the lower half of the circuit shown.

Why would this configuration be used and is there any advantages/disadvantages to using it this way.


texts: Turning potentiometer changes other potentiometer's value(STM32)

texts:
I have finished building my DIY simulator pedals for PC hacking together a 2-pedal set and adding a third.

Pressing the Gas pedal. All good

Pressing the brake pedal.All good

However when pressing the clutch pedal it increases the value of the brake pedal a bit

I they share the same ground and 3.3v and the output pins are connected to A0,A1,A7 and i am using the FreeJoy firmware to act as a HID device.

The potentiometer that i added is a 220K ohm one and the other 2 measured are about 44k(couldn't find a writing).

Here is the schematic

simulate this circuit – Schematic created using CircuitLab

I am a novice in electronics(am a informatics engineer student).Any help is appreciated.

Update #1
Here is the code for the sampling rate

for (int i=0; i<MAX_AXIS_NUM; i++)
    {
        if (p_dev_config->pins[i] == AXIS_ANALOG)       // Configure ADC channels
        {
            /* ADC1 regular channel configuration */
            ADC_RegularChannelConfig(ADC1, channel_config[i].channel, i+1, ADC_SampleTime_71Cycles5);
            axis_num++;
        }

    }


texts: Current in Secondary Windings of Toroidal Transformer

texts:
I am trying to design a toroidal transformer with multiple secondary coils. The core of the transformer is rated at 2500VA. Each of the secondaries powers a dc servo motor wich is subjected to a highly dynamic load.

There are 3 motors that require 24v at 3-30 amps depending on the load, and 2 motors that require 15 volts at 1-7 amps depending on the load.

If I were to make a secondary winding for each of the motors, how would I calculate the current in each winding?

I know the formula for an ideal transformer is: Vs/Vp=Ns/Np=IP/Is
but if the 3 24v motors are simultaneously drawing huge currents, does that mean the other motors will have too much current or is "Is" in that formula just the maximum available current and the motor will draw what it needs?


texts: Can a linear motor output multiple and precise linear forces?

texts:
I am trying to identify a motor-driven system that can produce a constant linear force in one direction.

The context for this is an injection device that compresses the plunger of a syringe (similar setup to this open source syringe pump).  The actuation (injection) needs to be performed at a precise and repeatable force.  I'm not trying to control for the speed of the linear motion, only the force driving it.  The linear force then determines the speed (flow rate) of the injection based on the fluid dynamics of the drug solution.  For example, at a constant linear force, a higher viscosity drug will be injected at a slower rate than a lower viscosity drug.

I would like to be able to generate different linear forces from a single motor in order to achieve different injection speeds. I know a stepper motor can not achieve this as it only operates at maximum torque.  Can a servo motor achieve this?

Also, is it possible to accurately set the force output (e.g. program one = 4 N ; program two = 10 N)?


texts:
A fun little project I've been working on is an EMF detector using my recently acquired Arduino. It is based off of the guide at http://www.aaronalai.com/emf-detector, primary differences being my own implementation of value smoothing and outputting Geiger-counter-style popping with a piezo element (just because it sounds cool, hehe).

Now from what I understand the principle behind the operation of the detector is that changes in electric fields are inducing a potential in the antenna wire, which is then read by the Arduino... However since I'm quite new to the whole electronics scene I do not know the function the 3.3 meg-ohm resistor holds (it grounds the antenna wire, as seen in the link above), and more specifically, what kind of effects increasing or decreasing the resistance actually has on the setup (yes, I have tested this, however since the setup is so so sensitive I can't discover a pattern... I figured finding what makes it work would help).

So if someone could explain the effects of the resistor in the circuit, it would be greatly appreciated (more so if any proper terminology is pointed out, its a learning experience for me!)


texts: Logic Circuit Transistor Resistor Values?

texts:
Last week, I posted a problem with a logic circuit (Need Help With Transistor Logic Circuit Design), and Analogkid was kind enough to solve it.  However, at the time, I didn't realize I still had a couple of biasing issues to iron out in the rest of the design.

One of the issues that has cropped up is that the input switches have a 1M ohm residual resistance when open.  This is causing Q1 and Q2 to forward bias when SW-1 and SW-2 are open, leaving LED-1 partially lit.  I need to calculate the resistance values of R5, R6, R7, and R8 such that Q1 and Q2 are 30% of the way into saturation mode when SW-1 and/or SW-2 are closed, and in cutoff mode when they are open.

I can not change the resistance values R1 and R2.  They are fixed.  Note that R3 and R4 are simply to compensate for diodes D1 and D2 to bring the current draw across LED-1 to exactly 10 mA when SW-3 is closed.

Also, a "0" ('zero") in the truth table equates to a switch being open.  Here is my schematic:

Any help would be sincerely appreciated.

Simulate at falstad.com


texts: IEC60950: cable distribution network definition

texts:
The definition of a cable distribution network is given in IEC60950: "mainly intended for transmission of video and/or audio signals between separate buildings or between outdoor antennas and buildings".
Should this clause be applied to a GPS repeater that does not transmit audio or video, or should it be taken as a telecommunication network?
Thank you.


texts:
I want to use LCD driver pins to light up LEDs instead of using LCD screen.
This is done on a broken device so altering other pins is not possible for this case.
Is this safe to CPU to connect just with limiting resistor or should I use a transistor driver for it? If so, are there any IC's to do this to avoid having a bunch load of transistors on board.

I am using EFM32 Gecko for this.
https://www.silabs.com/products/mcu/32-bit/efm32-gecko


texts: Supercapacitor with a rated voltage value greater than 2.7V feasible?

texts:
I've been researching into the development of electrical power units for Automotives (motorsports in particular, as I participate in my Uni's Formula Student team) and have started by looking into the applications of supercapacitors for energy storage purposes. I'm seeing a pattern, were all supercapacitors currently on the market are rated at max, 2.7V (with some pushing close to 3.0V) without any real reason why.

Compared to standard electrolytic capacitors (which I've viewed types that can withstand 1000V comfortably) I understand that the construction is different however I'm not exactly sure why this has such a drastic effect on the max voltage. Would there be anything on the quantum level that stops a supercapacitor having a rated voltage greater?

My suggestion is that maybe the Helmholtz regions that hold the capacitance has an effect on the maximum voltage that can be but I'm not entirely sure (just an educated guess)


texts:
I am new to this site.

I have a circuit and need to measure the current through a diode.

In my circuit i have a resistor and then a diode.

Do i connect the multi meter where i have in the picture? After the resistor, just before the diode to get measure the current through the diode?

Thanks.


texts: Arduino, best way to talk with multiple SPI devices (LED drivers)

texts:
(this is more hardware design, rather than software question).

Hi all. I plan to build an Arduino shield (board) with multiple LED drivers (TLC5941). They are accessible via SPI. The problem is that SPI communication wires may get loo long, causing signal interference.

Guessing my board should get another cheap controller to talk both to Arduino and LEDs; so, the question to all the experienced Arduino pros here is:

is it smart to connect peripherals (SPI) using some cheap controller as a cache? (at least this way allows me to send only modified values from Arduino => lesser code)
or the SPI bus is interference-proof enough(at least if the board is designed correctly)?


texts:
I was wondering what the difference between EEPROM types are.

For example 24S128 and 24LC128. My understanding is that typically the later digits, 128 in this case, represent the amount of space available on EEPROM. But what does the 24 and the S/LC/C/AA stand for?

Thanks


texts: Which sensor to use for detecting nylon string vibration?

texts:
I need to detect motion on a nylon (transparent) stringed instrument.

When the string is plucked, it would vibrate and I'd like to know what kind of sensor to use in order to detect the action.

Maybe a reflective optical sensor (visual detection) like the ones here? http://www.vishay.com/optical-sensors/reflective-outputisnot-16/

Or a tiny piezo element (detection by sound)? https://www.sparkfun.com/products/9199

I don't think piezo will work because there are more than one string to detect. The strings are close to each other, I guess the sounds will interfere with each other. Maybe using a treshold and computing/choosing the loudest emitter would be a solution. But I would prefer the cleanest way to achieve this.
At best, I do not want to paint the string thinking that it will damage the sustain and / or the color of the sound.


texts: LT-Spice wont open file -> File limitations?

texts:
I am currently working on bulk simulations. For this I created a Python script which writes in the .asc files of LTspice and creates long tables, which are stepped through with the run variable. This is to write predefined simulation runs.

I need to create files which run about 1,000,000 simulations long. After I ran the python script the file was about 2.7GB big. But now LTspice refuses to open it. When I try to open it it loads and after a minute or so it just closes the window without any message or notice. And there isnt even a crash note.

According to LTspice, there should be no file limitations, but I think there actually is one. And my PC cant be the problem, I have 64GB of ram and a 12 core processor (Ryzen 9 3900x).

So how do I solve this?


texts:
I am trying to mitigate between costs, ease of mounting, of enclosure matching and costs for a smallish PCB (< 100 g / 4 oz and about 35 x 50 mm / 1.5 x 2 in) used inside a passenger car.
And so far I have found these methods:

Snap-in universal anti vibration guides:

Double sided adhesive tape:

Adhesive standoffs:

Vibration dampers:

Spring washers:

Staking and potting I think are a bit too much. Any experience with the above methods you could share ?
As a side note, would it hurt not to use any anti-vibration mechanism at all in my scenario ? Largest component would be a button press switch.


texts: Is it possible to boost 60V DC to 400V DC using a dc-dc converter which is capable of delivering 50KW?

texts:
I am trying to simulate the current EV charger model. According to my research, I found that the 3phase AC at 400V (Phase to Phase RMS) transformer is directly connected to a filter circuit and then to Vienna Rectifier and then to a DC-DC converter. I have till now simulated in Matlab using an inductor filter of 48mH rated at 400V and 20A.(I am guessing the inductor of this rating can be easily accommodated in an EV charging Port). The output of the Vienna rectifier is 14A and 60V DC. (The Load is 50KW resistance which is I presumed to be equivalent to a battery of 50KWh).
Now I am thinking, Is it possible to step up 60V DC to 400V using a DC-DC converter to charge an actual battery of 50KWh.(Basically Fast charging).
Please correct me if I am wrong anywhere or please add anything you think is appropriate.
Thank you


texts: I need to design a second-order high-pass filter, gain 2 and cut frequency of 500 Hz. Using chebyshev response of 0.1 dB

texts:
I took the parameters from the MT-206 table of Analog Devices. I did not find in any book the chebyshev response of 0.1dB. https://www.analog.com/media/en/training-seminars/tutorials/MT-206.pdf

I performed the following steps to find the value of the elements

First: I'm pretty sure this is wrong.
Second: I have to take into account the Q of chebyshev's answer or I can only take into account the gain I want out of 2.
Third: The gain over there is almost around 5. Is there a way to "decrease the gain"?


texts: Do these two DPDT relays function the same?

texts:
If I do a search for a DPDT relay with 120VAC coil voltage, 30A and 220/240VAC contact rating as the parameters, I get results that look somewhat like the 2 examples listed below. What is it that sets them apart functionally? What am I looking for in the specs that tells me whether it will work for a motor/pump or otherwise?

DAYTON Relay, Power, DPDT, 120VAC
DAYTON Relay, DPDT, 8 Pins, 120VAC

I am working on a brewing system and the plans (diagrams but no schematics) call for three relays with the above parameters. Two are for two 110VAC pumps (3). The third is for voltage and amperage meters (4).  You can find the diagrams here:

Control Panel step 7: Wire up volt and amp meters

Control Panel step 8: Wire up pumps


texts: Reducing the voltage drop on a simple comparator driving a MOSFET to avoid LiIon overdischarge

texts:
I would like to use a LiIon cell recovered from an old laptop to power my bike light (a bulb one, 2.4W 6V).

I thought about using an opamp controlling a MOSFET to avoid overdischarge (MOSFET ON for Vbatt>3.1V), and also an opamp to signal when the battery is almost drained (LED ON for Vbatt<3.2-3.3V).

As DC-DC step-up I used a small board meant to be used for phone chargers and I measured an output of 4.8V with the load connected. It is way lower than the nominal 6V of the light bulb, but this is a minor issue, since I can easily swap that circuit with another one.

The circuit is (of course the LM7805 is a placeholder for the step-up board and also my MOSFET is different: a BUK556-60A I had lying around):

simulate this circuit – Schematic created using CircuitLab

My problem is that the LM358 (or the TL081 I have at home) is not rail to rail and apparently its output cannot put the MOSFET in saturation. For example, I measured on the breadboard the following values: 3.48V Vbatt, 3.17V threshold for the comparator OA2 (it was not 3.1V as I wrote above) and 3.9V on the gate of the MOSFET (and on the output of the opamp) resulting on a drop along the MOSFET of 0.8V.

How can I prevent overdischarge of the LiIon battery without losing almost 1V on the switch I have to place inevitably somewhere? A NPN transistor would not change the situation much, I think.

Update

This circuit technically doesn't prevent the batteries to drain, but it will light up the LED when charge is low and will stop the bike like altogether when the battery is almost empty, resulting in me being forced to charge the batteries.

I didn't show in the circuit the physical switch I plan to use to disconnect the batteries completely when no light is needed.


texts: Which circuit is better for low-noise, high-precision light sensing?

texts:
Circuit #1:

Circuit #2 (R is small, and Vout is amplified using the same op amp in the above circuit, which is not included in the image below):

My voltmeter (an ADC) has a low input impedance (10k Ohms).


texts: Driving 3.3 V LEDs with an Arduino and a shift register

texts:
I'm planning to build a simple LED matrix with an Arduino and some 74HC595 shift registers. However my Ardiuno outputs 5 V to the registers which will pass that 5 V on. How and where along the line do I reduce this voltage to 3.3 V?

Edit: Found this after a while of Googling. Is a resistor in front of every LED all i need (which i need anyway)?

(5–3.3) / 0.02 = 85 ohm for a 20 mA 3.3 V LED?

Edit 2: Can i provide 3 V from a different source to the Vcc pin of the shift register, but send 5 V logic on the serial pins? Im guessing that won't work but just wanted to double check.


texts: What's wrong with this audio amplifier and stereo to mono circuit?

texts:
The image below presents part of a schematic of an MP3 decoder (VS1003) with stereo -> mono conversion and audio amplifier to connect a speaker.
The problem is that after assembling the PCB barely anything could have been heard. I (kinda randomly) shorted R17 and C28 node to AGND and after this I can hear the music (this basically removes C28 and LEFT audio channel), but the sound quality is still terrible with a lot of noise.
I guess I did something wrong on the schematic. Can someone find a mistake here? What could be corrected to get this right? I would be happy to have even 1 audio channel.


texts: Grouping input and output signals with the corresponding clock

texts:
In my Verilog design, I have two asynchronous clocks, clk1 and clk2. Associated with each clock is a bunch of inputs and outputs.

At the moment, my compiler (Quartus II) is not complaining when I mix I/O signals associated with clk1 with I/O signals associated with clk2. This is bad because the signals need to be synchronised when crossing clock domains.

What is the best way to constrain I/O signals to an associated clock? I have seen the SDC commands set_input_delay and set_output_delay, but I have set all the delays to 0 and I fear this might be the wrong way of doing it.


texts: Can leaving a Geiger–Müller tube energized continuously cause it to wear out?

texts:
I recently acquired a Geiger counter to feed my raging paranoia curiosity.

However, I am wondering if it could harm the Geiger–Müller tube to leave it energized continuously?

I know a couple places (spark fun, for one) Have continuously operating Geiger tubes.

However, my understanding of how they work is that when the gas inside gets struck by a high-energy particle, it causes an ionization path to form between the electrodes. This makes me think that it might cause pitting and evaporation of the anode over time.

Do Geiger–Müller tubes wear out over time? And if so, what it the mechanism that causes the wear?


texts: Do external EMFs affect in some way a capacitor?

texts: I Know that inducters are affected by external magnetic fields .The affect depends on the construction of the inducter  . What I would like to know is how capacitors are affected by external electrostatic fields ?   Mutual inductance is well covered elsewhere but what about mutual capacitance?


texts: Conditions for maximum power transfer in an AC circuit answer

texts:
This question has no satisfactory answers yet so i just tried

  Conditions for maximum power transfer in an AC circuit

  Now i stuck at the equation 1 and 2 and don't know how to solve them further ?
  Also is my logic correct ?
   Please help me


texts: What is the purpose of this inductor and cap on a RF line?

texts:
I'm busy looking at the layout guide for a chip antenna (Taoglas Limited ILA.08).

On their evaluation board, they have parts #6,7 included:

But in the layout mentioned later in the doc, they are not included:

What are they for, and do I need to include them?

Note: this is the layout for the RF IO coming from the module that will be connected to the antenna, where C4 is 100pF, L1 is 47nH and R2 is 0Ω


texts: ac phasor voltage between capacitor and inductor higher than source voltage?

texts:
I've just learned about phasors and I am very confused about this. Take this circuit as an example:

simulate this circuit – Schematic created using CircuitLab

So by what I've learned, All I would have to do is use the voltage division formula, after computing impedances:

z1 = -j

z2 = j

z3 = 1

Now I combine z3 and z2:

z* = z2 + z3 = 1 + j

And now voltage division:

Vm1 = 10 * (1 + j) / (1 + j - j)

Vm1 = 10 * (1 + j) / (1)

Vm1 = 10 + 10 j

Vm1 =  14.14 (angle 45)

???????

Somehow, the voltage at this location is higher than the source voltage. how could this be?

Is it not a violation of KVL?

Thanks so much for any answer.


texts: How can I make this USB-C connector as a host?

texts:
I want to make a USB 2.0 Cable for some gadgets with a USB-C to USB-C connection.
I want to intentionally make connector end = host, and the other connector end = device. I've read around that I can do this using resistors, without the need of attaching another wired connection to both ends, but I am not sure how.

Any guidance on how I can achieve this? The connectors I am using are the ones below.

Thanks!


texts: I know energy & frequency is equal to each other so if i increase energy i increase frequency. if i add more voltage into my medium it should increase the frequency but let say i add more energy into my system lets say its a gas and its emitting white hot light. I increase the energy but the color remain the same. But if the frequency was increasing wouldn't the color change? Or is it the fact that white light is the mixture of all colors so the frequency is increasing its just i don't see it with the naked eye? Is increasing voltage enough to add energy into my medium or is there another way?


texts: How Charger and Cell Balancer work in BMS?

texts:
I'm currently working on BMS for LiIon 4S2P battery pack. Two core components I've choose are BQ77915 balancer and BQ2954 charger from TI.
For now, I stick to example schemes from datasheets, but I'm curious about one thing:
How to properly connect these two "systems"?
Will charger think "I'm not over with charging" because balancer will be in proccess of balancing those cells? In other words, will charger know when his job is done, even while balancer is balancing cells?
Here is a scheme - example schemes connected.

Thanks for help!


texts:
I am facing this problem, it may appear that I am asking an answer for homework, but it is not.

I am studying load frequency control, and it was given a series of problems like this:

The solution is quite easy, however the new output of one of the units is greater than the max output, in this case, unit 3 new output is 157MW. I asked to my professor how should I approach the question if this issue appears, He said it should be obvious and I should think about it.

Then...I am thinking and thinking and thinkig, and I can not see a solution different from taking the excess from unit 3 and give it to unit 4 for example, however, i am sure it is not easy like that and it must have a mathematical explanation and more important, an important concept i am missing.

Could you help me understand what I am missing here? thanks


texts: PIC16F628A: 500ms delay (w/Timer 1) not as expected

texts:
TL;DR: See the last few lines (and the quote) at the bottom.

Just a word about my background: I learned microcontrollers last semester with the 8051 and have been learning PIC microcontrollers over the summer. I've spent most of my summer working with the PIC12F683, and I'm just starting to learn the PIC16F628A. This is all to say that I'm not totally new to microcontrollers or PICs.

Since I'm just starting out on the 16F628A, I decided to start by blinking a LED. (I'm using a PICkit 3 and MPLAB X IDE v3.00 on Linux Mint 17.) To do so, I wanted to use Timer 1 to create a 500ms delay. The delay is substantially off from 500ms, and I want to understand why.

Since there's no auto-reload feature (like on the 8051), my idea was to use a 1:8 prescaler. Then, every time Timer 1 overflows, initialize it to 0x0BDB. That value creates an interval of 0xFFFF - 0x0BDB = 0xF424 before the overflow (or 62,500, in decimal).

Since I'm using the internal clock (4 MHz), and the Timer increments as FOSC/4, and I'm using a 1:8 prescaler, the period of the delay should be:

1 / (4 MHz / 4 / 8 / 62,500) = 0.5 sec

My LED is blinking, but the delay is not 0.5 seconds. I used my multimeter to measure the frequency, and the result works out to a period of about 0.417 sec. Also, this works out to about 144bpm, and when I set a metronome to 144bpm, it matches with the blinking LED.

The only things wired to my breadboard are Vss (pin 5), Vdd (pin 14), an LED (with a 10kΩ current-limiting resistor) on pin 6 (RB0), and a 47kΩ resistor between MCLR and Vdd (pins 4 and 14). (...and my PICkit.)

Here is my code:

#include <xc.h>

#pragma config FOSC = INTOSCIO  //oscillator selection; use internal oscillator
#pragma config WDTE = OFF       //disable watchdog Timer
#pragma config PWRTE = OFF      //power-up timer disabled
#pragma config MCLRE = OFF      //use MCLR pin (internally tied to Vdd) as a digital input
#pragma config BOREN = OFF      //disable Brown-Out Reset
#pragma config LVP = OFF        //disable Low-Voltage Programming
#pragma config CPD = OFF        //data code protection disabled
#pragma config CP = OFF         //code protection disabled

bit LEDstatus;

void main(void)
{
    LEDstatus=1;            //initialize LED off (active-low)
    TRISB0=0;               //use RB0 as digital output

    T1CON=0b00110000;       //Timer 1 off; 1:8 prescaler; use internal clock

    TMR1H=0x0B;             //initialize Timer 1 to get a 500ms delay
    TMR1L=0xDB;

    INTCONbits.PEIE=1;      //enable peripheral interrupts (i.e., Timer 1)
    PIR1bits.TMR1IF=0;      //clear Timer 1 interrupt flag
    PIE1bits.TMR1IE=1;      //enable Timer 1 interrupts
    INTCONbits.GIE=1;       //enable all interrupts

    T1CONbits.TMR1ON=1;     //turn on Timer 1

    while(1);               //wait for interrupts

    return;
}

void interrupt ISR()
{
    if (PIR1bits.TMR1IF==1)
    {
        PIR1bits.TMR1IF=0;          //clear interrupt flag

        T1CONbits.TMR1ON=0;         //turn off Timer 1
        TMR1H=0x0B;                 //initialize Timer 1 for 500ms delay
        TMR1L=0xDB;
        T1CONbits.TMR1ON=1;         //turn on Timer 1

        LEDstatus=~LEDstatus;       //toggle LED
        RB0=LEDstatus;
    }
}

TL;DR: I know that stopping a timer, reloading it, and restarting it will (in general) cause some delay, but why is the PIC shortening my 500ms delay interval by over 80ms?

I think I've found a hint as to why this isn't working, but I don't quite understand the details. From p.53 of the datasheet:

  7.7 Timer1 Prescaler

  The prescaler counter is cleared on writes to the
  TMR1H or TMR1L registers.

What exactly does this mean? Does the prescaler become some value other than 1:8 for some amount of time when I write to TMR1H and TMR1L?

EDIT: I've also just tried using the Compare function of the CCP module, and the delay is still the same inaccurate value. Could I have a bad chip? Could the internal oscillator really be that far off?


texts:
An ideal transformer should have insignificant power loss, meaning, input VI equals to the output VI.

Question... To achieve this is it true the transformer must have equal copper volume in its primary and secondary windings?

I recently unwound the whole secondary from a 1000VA EI core transformer. This is done without cutting or disassembling of the core. On top of the original primary, I wound 10 turns of 12mm^2 copper wire which gives me about 10 volt which should (theoretically) be able to deliver 100 Amps.

Not knowing anything about primary copper volume, I am wondering how efficient this transformer will be.

Any advice is appreciated.


texts:
this is a bit of a long shot but here goes.

I need to buy a speed controller for an electric ride on car and I've had no success in finding one with a reverse polarity switch and one that also accepts a hall sensor as a throttle, they all come with potentiometers which are useless to me.

So, I know i can use a DPDT relay or a switch to change polarity but as there'll be currents in excess of 20a going through the relay at times, i don't want that relay near my son's gear shift, in case it fails under load.

My thinking is to have the motor connected to the relay/switch to take the brunt of the current and control the relay/switch with the gear shift that is a DPDT on,off,on switch. Is this possible?
I just can't figure out how I would wire up the switch to the motor connected relay/switch to control it...any ideas?


texts: Is shorting two power rails with a capacitor like this OK?

texts:
I am using this CAN transceiver which runs on 5 V but, if you provide it with the microcontroller voltage on its VIO pin, then it will automatically apply voltage level correction for the micro.
The following has been mentioned in the design notes:

As you can see, they suggest creating a high-frequency short circuit between the 3 V and the 5 V using a 100 nF capacitor.
Is this recommended practice? Must I be wary of anything because of it?


texts: I am looking for a very small switch that will switch on then off in response to a single impact. Physical size about 4mm cube but smaller if possible. It is for a project to make a training aid for target shooting athletes


texts:
I'm using an FSA9485 Multimedia Switch (MMS) for audio recording via USB headset.  So far, just noise is recorded...so I'm wondering if the MICBIAS is working correctly.

The MMS schematic shows MICBIAS applied on the codec side of the MMS, which is how we've implemented it:

[

The headset MIC pin is connected to VBUS_IN of the micro USB connector.  I've measured voltage at VBUS_IN, and don't see any amount of bias voltage.  At the codec, MIC/MICBIAS is roughly 1.2-1.4V.

Will an "ear bud" style microphone work with no bias?  I presume the bias voltage should be present at the connector so that it can properly bias the headset mic.

Link to headset

EDIT: Turns out I wasn't contacting the micro USB VBUS or GND pin properly with my multimeter and the 1.4V bias is present at the connector.  It's working properly for me with the bias.


texts: Trying to understand this oscillator... there's no emitter grounding or bias

texts:
I dissected and drew up this oscillator circuit from a cassette machine the other night. It's purpose is for biasing the tape. I'm curious though as to how this oscillator functions since the base is not grounded. It measures a negative dcv at the base. It produces a clean hv ac sine wave after the 562 cap... but why, or how? What is the purpose of the bypass cap in the circuit? What would happen if the input voltage were increased?

Update
The TO-92 says c3377 which seems comparable to a 2sc3377 npn transistor.

Also, I have been researching transistors without bias and came across this... "Ever wondered why VBE is always quoted as 6V for silicon transistors? The reason is that a zenner effect takes place at
around 8V. Now, if you actually use a significantly higher voltage, but current limited via a resistor, then the zenner
effect will allow enough base leakage current to pass to make the device conduct as if a bias had been applied. This
conduction holds the emitter (now collector) at this zenner voltage."
Is it possible this is how the circuit is functioning? After quadruple checking the pcb there are definitely no bias resistors on the base.

I have some parts coming and will breadboard it to verify the schem too.


texts: (NPN) Why is the collector current at saturation, less than the collector current in the forward active mode?

texts:
Why is the collector current at saturation less than the collector current in the forward active mode?  Specifically,

Why is \$ I_C < \beta I_B \$ ?


texts: Switch 12V loads with MCU and BDW93C darlington or IRF630N

texts:
Task is to switch 2 loads with an MCU (3.3V 10mA max) and few IRF630N, BDW93C and sample pack of S901x transistors (of switch relevant components).

12V loads, likely important context for question:

0.3A 3-pin fan, want speed control, research points to low frequency PWM method
2A XL6009 based boost converter with enable pin, which in turn feeds 24V ultrasonic mist driver (picture 3). Duty cycle around 20s/on 300s/off so I figured keeping converter always connected and switch 24V is not optimal, please point if wrong

According to my poor understanding of datasheet, IRF630 would barely open at 3.3V so additional transistor is needed to run it, so I tried darlington first and am very surprised at observed voltage. Open state: -1.1V closed: short burst to 18V, then steady 12V as wanted. Don't have oscilloscope yet, measured with cheap digital multimeter.

Question 1: please explain negative and burst voltage on load connector. Is it bad? If yes, how to fix it?

Question 2: please advice how to properly switch described loads with listed components.

simulate this circuit – Schematic created using CircuitLab

Just in case I messed up wiring, here is real photo. Long "bus" wire on the right is common. BDWs' pin 1 soldered with limiting resistor to GPIO wire. BDWs' pin 2 go to their load (-). BDWs' pin 3 connected to common.

Photo of load2, XL6009 based DC-DC converter with enable pin and its load, ultrasonic fog device.


texts: Problem with circuit cam, can't view my top layer?

texts:
I have a circuit laid out in allegro and I'll be milling it out on a board router. I'm using Circuit Cam to produce the files needed for the board router. I have three layers, a top layer, a bottom layer, and a mech layer. I also have a drill file. When I import my files, everything looks fine except for the top layer, which has all of my routed traces. When I view the top layer all I see is a big white rectangle. I will post some pictures in a couple hours. But has anyone used circuit cam before and had this problem?

The first image shows my allegro layout. I opened up the film control to show that the TOP layer has VIA CLASS/TOP, PIN/TOP, AND ETCH/TOP. When I import this to circuitCAM, however, I get the white rectangle on the second image.


texts: BJT switch: Exact base resistor to limit current, or allow more current than needed & then use a current limiting resistor?

texts: Is it better to adjust the base resistor of a BJT switch to get the exact current you want for an LED or other component in the main circuit? Or is it better to have the BJT switch allow more current than needed in the main circuit and then use a current limiting resistor there?


texts:
I have an exam in three hours and there seems to be a recurring question in all previous years questions:

Why are cooker units diversified while air conditioners are not?

I've searched a lot but have not found a satisfying answer, please explain it as simply as humanly possible.


texts: When to use a 2 pole circuit breaker over 1 pole

texts:
We are currently designing a product that connects to 230VAC mains power (single phase) (South Africa). It has a simple 12v switch mode power supply that runs the electronics. We want to put a Circuit Breaker between the mains and the PSU.

What I want to ask is, under what circumstances would one install a single pole circuit breaker vs a 1P+N circuit breaker?

The purpose of the breaker, is just to ensure that should any of our equipment short, break, get hit by lighting etc that the breaker will trip, and not affect other the main power in a negative way. I am essentially using it as a re-settable fuse.

We are considering the following two circuit breakers:

Single Pole
1P+N

The 1P+N is roughly 4 times the price of the single pole.

This cost saving could drastically effect the product price, however I do not want to compromise on quality & safety of the product.

Maybe someone could also clarify the difference between a 2P (2 pole) and a (1P+N).

I generally like to install the 2 pole in my own equipment, that way when i'm working on the unit, I know that it is totally isolated from main power. But I feel this is overkill for a product in the field.


texts: Trouble understanding Alternating Current (AC)

texts: How does alternating current get anywhere if it travels "back and forth" in the wire?. I understand that Direct Current is a flow of electrons through a wire, but I have always been confused with how Alternating Current works. I expect I am missing something simple but could anyone point me to a resource that does a good job of explaining AC, or perhaps offer an explanation themselves? Thanks!


texts:
I have this small mosfet with pins that are about 1mm in length that I need to solder to wires that are maybe 3 times larger than the pins.

Should I just drop blobs of solder on it or is there a better way to approach this problem?


texts: Wiring Emergency Stop button to disconnect two independent circuits

texts: I am trying to use one emergency stop switch to disable two batteries that function in independent circuits. My circuit diagram is attached below. A motor controller connects to each of the exposed wires. Will this circuit work?


texts:
Can anyone tell me if there are certain specific criteria that states whether an infrared led can be used as an illuminator particularly the ones they use on hunting scopes.

Would a tsal6100 for example perform well with an infrared scope I understand you would need a lens which I have access to but what makes the diodes used in hunting scopes so different?

Datasheet for tsal 6100

I know the wavelength for the scopes vary between 850-950nm but there doesn't seem to be any clear guide what works better and I believe it depends on the infrared cameras sensitivity.


texts: Choosing the right power-switch with LED for a simple electrical design

texts: I want to add an ON/OFF switch with an integrated indicator LED to a very simple electronic design, between a 9v battery and the connected module that it powers. What should I be looking at to select the power switch ( specifications ) and can I connect it like any simple power-switch ?


texts: Do I really need to learn how to use registers - Programming a microcontroller?

texts:
I have a curious question. Do I really need to learn how to use registers when I program a microcontroller?

I have been using Arduino for a long time. I quit using Arduino and starting to use STM32 because they are more cheap, faster and just better microcontroller. They do require more knowledge about C programming and what a microcontroller can do, because you can do more with STM32 than Arduino.

Anyway! I have tried to blink LED and read digital inputs e.g toggle with a STM32 by program it with registers. It's time consuming and painful. Luckily STM offer CubeMX so the user can setup a complete project with HAL-libraries without using any registers. Super easy and super fun!

This is how Atollic CubeMX looks like.

And now my real question, why I started this question.
I have been using Atollic TrueStudio. Works fine. But today I upgraded my Atollic TrueStudio and STM have implemented CubeMX into Atollic TrueStduio. Before I have to download both Atollic TrueStudio and then CubeMX. Seperate software in other words.

But today Atollic TrueStudio and CubeMX is merged together into one software. Great! That's really good.

But...to create a project for a STM32 microcontroller, you need to create a CubeMX project. There is no "Create a blank ARM project in C" as it was before. Now is like "You want to create a STM32 project? Well, you never going to use register anymore so we choose for you! Here, have a CubeMX with HAL-libraries project! Ready to run!"

Well...that's great! But do STM assume that working with registers is not necessary when I use STM32?

I have no problem to use SMT32 with CubeMX + HAL libraries. Not at all. But I'm worried if I become "stupid" if I use CubeMX + HAL just to make it easy for be.

Should I program a STM32 with registers or should I use CubeMX + HAL libraries? Notice that this is a 32-bit microcontroller of tons of documentation and not a simple AvRTiny8.

Today I create large projects with STM32 thanks to CubeMX + HAL libraries. I could never do that without this technology.

Here is the reason why I use STM32. It's just.....better if you compare the price and what you get.


texts:
Could anyone recommend any Wizard-like tool for creating USB device descriptors?

Most (all?) USB firmware examples I've so far looked into define the descriptors as simple byte array in .c file, filled manually (with a little help from macros).

It's not a black magic, obviously, still I believe that a simple specialized tool could be useful. Googling for it gave no useful results, however...


texts: Need help identifying this component recovered from a Fostex X28

texts: This has been taken from a Fostex X28 4 track recorder and requires spares. I am not familiar with this component and I am unable to find information online. Does anyone know what it is and if there are any equivalents?


texts: I want to have my Arduino control several SPI slave devices, among them a 74HC595 shift register. I've having some trouble understanding how to properly handle communication - I get that the Slave Select (SS) should be tied to the Register Clock in so that it is enabled when low, but wouldn't the parallel output keep changing when sending serial data to other SPI slaves (having SS high)?


texts: Can I program 5V ATmega328P using 3.3V ICSP bus?

texts:
I am considering building a microcontroller HAT for Raspberry Pi Model B+. Since the Pi have the SPI bus exposed and some avrdude fork supports using it directly, I am hoping that my HAT can allow Raspberry Pi talk to the ATmega328P using SPI ICSP for flashing the chip instead of using serial and some serial bootloader. However the pins should be disengaged from the Pi when not required so that other SPI peripherals can be connected to both devices too. Similar situation exists for I2C, UART buses and one GPIO pin. All pin dis/engaging is done using one PCF8574 chip on Pi's I2C bus.

I know very well that I can run the ATmega328P at 3.3V, possibly overclock it to 16MHz, but I am asking about doing this with the microcontroller running at 5V. At 3.3V disengaging the pins requires just some CD4066s


texts: How Do They Make Surface Mount Capacitors and Resistors?

texts: With the ever decreasing size of surface mount resistors and capacitors, how do they make such small components?


texts:
What is the best form to transform a logic function to before to convert all gates to NANDs, so that we have a minimal number of NAND gates?
Is it minimal sum of products, minimal product of sums or something else?
The same question for NOR.


texts:
I was looking through some problems in Nilsson's book and this one caught my attention:

The variable of the dependente source is in the \$4\Omega\$ resistor, which is part of a "delta" type of resistor's network. If I perform the delta-wye transformation: (1) the resistance values would change; (2) the variable could be in two different resistors. I made a simple simulation of another delta network comparing with the wye equivalente and the current values were very distinct, the topology of the circuit was also very different .The original problem wants you to use SPICE, but I am curious on how to deal with it theoretically, or if it is possible to perform the transformation in this case. Thanks for your attention.


texts: Why 'the electric current is “shorted out” by the conductor' in Stutzman-Thiele Antenna Theory and Design?

texts:
Page 346, in Stutzman-Thiele Antenna Theory and Design-3d edition, reads 'the electric current is “shorted out” by the conductor' and is thus nullified. Refer to part c of the image below:

In this page, with this sentence (as I understand), the authors are trying to explain Love's equivalence principle in the context of aperture antennas. With this principle, one can find the radiation fields of an antenna structure (enclosed by the closed surface S) if he knows the equivalent electric and magnetic currents on the surface of the antenna when it is difficult to find the actual sources and currents inside S. The formula for these currents, for the general problem in part b is according to the authors in the same page :

Next, the authors,using the general problem in (b), arrive at the special equivalent problem in (c) where E1, and H1 are zero and introduce material inside S, in particular a perfect electric conductor which does not alter the problem. The explanation follows:

So it appears that a closed perfect electric conductor cannot sustain a current on the surface. Is this reasoning true?


texts: PSPICE errors when capacitors are 0Farads

texts: I'm getting a value may not be zero error wheneever I try to simulate a circuit containing capacitors whose values are zero.


texts: compressed sensing on a non-sparse signal and Nyquist-Shannon sampling

texts:
Compressed sensing is often utilized on a sparse signal, allowing compression and sampling to be done in a lower rate.

What happens if compressed sensing is used on non-sparse signal and wireless signal? Will compressed sensing eventually produce a result basically equal to sampling Nyquist-Shannon theorem?


texts: ATX POWER_OK signal not provided to molex connected peripherals such as HDD

texts:
From Wikipedia:

  The Power Good signal prevents a computer from attempting to operate on improper voltages and damaging itself by alerting it to improper power supply.
  The ATX specification defines the Power-Good signal as a +5 volt (V) signal generated in the power supply when it has passed its internal self-tests and the outputs have stabilized. This normally takes between 0.1 and 0.5 seconds after the power supply is switched on. The signal is then sent to the motherboard, where it is received by the processor timer chip that controls the reset line to the processor.

We know than an HDD has as complex as an entire motherboard and has two or three CPUs with special purposes. I can't understand why the POWER_OK is required by motherboard and not provided to HDDs.

If the HDDs has the logic to check the power signal by themselves, or are using a self timer before setting the CPUs why the same has not been done for the central motherboards.

It was told here that "Peripherals can be fitted with their own voltage supervisory circuits" as the mobos has voltage tests shown in DMIbios that is also shown in some bioses settings menu.  It is reasonable that both has their protection so I cant't figure how why POWER OK exists if every hardware in the case is self caring.

Moreover the electronics that must check other electronics not to go crazy for bad power how can be trustable if is itself bad powered? Maybe that is the scope of power_ok since power supply can know something is wrong before the capacitors gets completely empty?

It seems reasonable that microcontrolles has a startup delay to spend before POST waiting for reset command. I suppose, please confirm, that after start up the design is (in case of power problems) to reset the  motherboard by dropping POWER OK. At this point is the motherboard responsable to send reset over sata bus?

In case of bad power, if the CPU is not left "going crazy" for a long time since is reset there is less possibility of data corruption. After the reset the CPU is not started if powerok is not up again, right?
Problem is if molex remains powered up since SMART is doing read and write job (during idle, since smart III it also rewrites older sectors). I am also wondering if hard drives has some capacitors for some instant of residual power.

Is seems to me an incomplete design: or power ok is not necessary at all or modern hard drives operating by themselves are incompatibile with that design. ( I tested by myself drives from HFST, Segate, WD and older IBM doing SMART activity with no data cable inserted so no initial reset received).


texts: Switch/Pushbutton for Multiple LED String Lights

texts:
I'm helping my daughter with a science project. We're designing a glove for crossing guards with red and green LEDs attached. I thought it would be a good idea to put a small button in the thumb area that when pressed would turn off the green LEDs and turn on the red LEDs. Then when released the reds turn off and the greens turn back on. Here are the LEDs we're thinking of trying:
String LEDs

Looks like I'll need to cut the battery pack and wire the switch/button in between. Where I'm struggling is what kind of button to use (SPDT/DPDT) and how to wire it.

Also, could I hack the battery pack and combine the wiring to make a master on/off switch that controlled them both?


texts: Stability problem OpAmp and FET source follower

texts:
I just found this site and read a few great interesting articles but nothing that would solve my problem I am hunting since a while.

I have a OpAmp circuit with a N-FET source follower that regulates the current of some LED's. LED current is set at 700mA.
The ripple on the LED voltage source is at around 590kHz and is seen at 20mV on the source shunt of 0.3R. This feedback goes directly to the OP-. The OP+ has a quite stable reference voltage. This means I can measure a 20mVpp ripple between OP+ and OP-!
When I measure the OP output and OP- I see that both signals have the same phase and are NOT inverted. This means that 20mVpp on the 0.3R shunt generates 40mV on the gate of the FET with the same phase. But it should be the opposite. So I guess the OP is not stable at this frequency.
Otherwise it works fine and regulates the current accurate and quick. It's just that there is lots of ripple noise (and thus current ripple) and I would like to get rid of it!
What am I not seeing or did wrong here? Any hints would be appreciated!

Here a scope picture.
The reference voltage at OP+ is stable. But I can measure a 20mVpp ripple between OP+ and OP-! This means the OpAmp is not really doing what it should do.

On the picture is the gate voltage with the shunt voltage as comparison. The shunt voltage (OP-) is yellow with about 20mVpp ripple.
The pink is the gate voltage at around 1.75V and it has the same ripple but with the same phase and 40mVpp.
I always measured with the short, spring type GND connectors on the probes and took the OpAmp GND as reference.

So my question is here: why doesn't the OpAmp try to remove the ripple as the feedback of the source is directly connected to OP-? Why is it running at the same phase? The GBW is at 2.2MHz. Isn't this circuit running at unity gain? What am I missing?
Thank you very much for any hints/inputs!!!


texts:
How to design pseudo dual port RAM using a single port RAM in Verilog ? What are the design considerations? Are there frequency limitations ?
Clarification on 'pseudo' dual port - single port RAM (1RW) with external logic to make it appear like dual port RAM (1R/1W).


texts:
I am trying to make an amplifier which should amplify signals from at least 10uV (lower better) to around 100mV or above. The signals range from a few Hz to around 100kHz. Adjustable gain is also helpful. I was planning to use ADA4528 for this. Please give some suggestions on this. Also, is ADA4528 a suitable choice? If not, please suggest some opamps which might help achieve this.

Thanks