texts: Wiring Diagram Help - 6v 'Power-Wheels' Ride-On Upgrade

texts:
Hello,
I have a 6v Ride On toy car that I want to upgrade to 12v without upgrading the entire electrical system as it is only design for 6v.
My issue? I'm not in the electrical trade and i'm trying to teach myself, and would like feedback on my wiring diagram. I'll try to provide as much detail as I can.
Working Description
For anyone not familiar with the type of car in question; currently, the 6v battery powers a remote control compatible system. When powered on, I can select between remote control or manual use, and select between forward and reverse when in manual mode. At either the press of the foot pedal or input from the remote control, the cars onboard PCB magically calculates an output and will send either a positive or negative 6v to the rear motors to go forward or backward respectively.
(I can upload a front and back picture of this PCB if anyone is interested in tracing it)
Plan / 'Wants'

12v battery
DC-DC buck converter, stepping 12v down to 6 for the car's system
Upgrade rear motors to be 12v compatible
Have a single DPDT switch to change between 6v and 12v power at the rear wheels. The switch will either use the direct 6v signal from the PCB to power the motors, or interpret that signal to allow the motors to draw directly from the 12v battery.
No items in stock. To complete at the lowest possible cost

Issue
I can easily achieve most of the above, except interpreting the reverse polarity to drive rearward at 12v.
Initially, when switched to 12v mode, I simply had the 6v signal power a mosfet which was the electrical switch to either stop or drive forward.
I then realised I need to be able to reverse as well and a double throw type mosfet situation doesn't exist (?).
My Solution
Disclaimer - I am no electrical engineer. I have basic skills and understanding of electrical diagrams. I have tried my best to make it as easy to follow as possible but I know it could be better, and not all correct symbols are used.

Explanation
FYI, I have not included any wiring that steps the voltage down for the PCB and anything to do with the PCB, even though that will exist in practise.
With the DPDT switch in the other position, 6v signal from the PCB is used to power the motors.
In the current positions depicted... the relays are wired to provide 'Normally Closed' positive polarity to the motors, controlled by a transistor (T1) that is powered by the 6v PCB signal.
If the PCB signal is reversed, NPN transistor (T2) should then activate, which in turn activates both relay coils. The reverse voltage will then flow directly through the relays and to the motor, being restricted by diodes. When the PCB signal stops, the relays cut power and further movement is ceased due to T1 not being activated.
Final Questions / TL:DR

Will this solution actually work?
Does T1 have to be a MOSFET (capable of up to 10A current)?
Are there improvements I can make to this solution in general?
What are some other, (likely) more effecient solutions for a similar cost price?
Any better post tags to help target this post to the right people?

Thanks so much for your time.
----------Edit----------
After seeing the initial comments and searching other forums, and learning that the relay contact voltage can be higher than the coil rated nominal voltage; I come across this solution... which other than using 2 batteries in series and lacking the ability to switch between 6v and 12v, is what I'm after. (Note, I already know it is a circuit breaker in the green circle... was added by another user)

I have translated this into a more accurate and fitting diagram for my application and would like to know if this is a viable and working solution.


texts: Why does a Tesla car use an AC motor instead of a DC one?

texts:
I was just watching a mega factory video and wondered why they use an AC motor which requires a power inverter instead of DC which may be powered directly from their DC battery? Introducing an inverter means more cost (weight, controller, etc).

Are there any reasons for that? What are the differences between an AC and DC motor that may have lead to this decision? Also does anyone know what kind of motor is used in other electric cars?


texts: microphone noise cancelation using two mics using AND function

texts:
First things first, I will clear up that this question is not about external noise cancellation.
Cheap microphone generates unwanted static noise, so i decided to array two microphones and use "AND" function to filter out signal that is coming out only from both microphones, because each microphone will have different noise from another, noise will be left out, leaving only recorded signal

will this work ?
how to make this ?
will phase be an issue ? even if they will be placed really close


texts: Why does my book's D flip flop differ from others?

texts:
My understanding of a D flip flop is that when the clock is high and D=1, it sets Q to 1. If D=0, Q is set to 0. So it is like a set to 1 if D=1 and reset to 0 otherwise.

The table repeatedly given in my book is:

D CLK Q QN
0 High 0 1
1 High 1 0
x 0  (last Q) (last QN)
x 1  (last Q) (last QN)

The book is: John F Wakerly, Digital Design Principles and Practices.

It repeatedly reuses this table when describing negative edge/enable flip flops. It seems like it is doing a T flip flop, basically. But it defines T flip flop later too.

Am I misunderstanding D flip flop? Why does the book differ from other sources?


texts: Using a mechanical switch on output of SR latch / OR gate?

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Will this cause any significant issues in delay or performance? Intuitively, I think the addition of a big switch on the trace will add additional inductance/capacitance, but is there a way I can better estimate the effects?
For reference, the transition and propagation time from the gate is ~10ns. Given my circuit is fairly sensitive to delays, would I be better off using 0 ohm resistors and solder/de-solder every time I want to switch?


texts: How to construct a discrete circuit to send out a square wave with N pulses?

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I want to build a simple and discrete circuit (without any integrated circuits) which puts out a square wave (50:50 duty cycle) with N pulses (rising edges)?
For example for N=4 the output should look like this:
The time of one period (from rising edge to rising edge) might be in the range of 10 - 100 ms.
Any ideas how to achieve this?
I thought on using a capacitor, which charges and puts out a square wave and another capacitor which "enables" (AND gate?) the signal and is sized the way that it enables as long as 4 pulses take. But I've no idea if this is even possible ...

Here are some more details:

The circuit should be discrete: using only transistors, resistors, capacitors (no "complex" devices/ICs)
The N is fixed, meaning that there is a N=4 circuit which generates 4 pulses on button press
"... good old dialphone's mechanical approach" - I've looked it up and this is what I want but not mechanically but electronically
"What is the maximum number of pulses you want to create, and how do you want to set the count?" N ranges from 1 to 9 and the circuit is built for N, so it is not variable.


texts:
Task: Construct an AND circuit with 8 inputs, a circuit which implements the expression a∧b∧c∧d∧e∧f∧g∧h.

Condition: Use only NAND-Gates with two inputs to solve this task.

Could anyone explain to me how to solve this question?

Thanks.

Edit: My thought would be to do sth. like this:

https://crcit.net/c/df53a1d9

Could that be right?

Edit: My new idea:

simulate this circuit – Schematic created using CircuitLab


texts: What is the purpose or advantage of using Slew Rate controlled output capability for GPIOs?


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I'm designing a 3V button cell battery powered device. I want it to beep or click or just make any noise at some times just loud enought to be heard across the room.

I've made a prototype working on 12v - it's just an opamp comparator that goes high and low and i've connected a piezo speaker to output of opamp with a cap in series. It makes clicks when opamp goes high or low and they are just loud enough, but when i lower voltage to 3v, i can barely hear the speaker.

Can anyone suggest me a solution?


texts: A few people have advised me to never solder a power cord directly to a PCB, but they couldn't explain why not. Why can/can't I solder it directly?


texts: I've created a custom title block for my schematics. The problem is that I've already started the project and it is in advanced state of progress. How can I update it? Is it even possible?


texts:
I have been experimenting with capacitors on a breadboard with a multimeter. A circuit with a diode and a 6v battery (and nothing else) gave the following readings on a multimeter:

Voltage: -4.81v

I replaced the diode with a capacitor, and got the following readings:

Voltage: starts at -6v and steadily decreases to -0.1v

I understand that a capacitor stores energy in its electric field and releases it when the current is low, but what are the properties of a circuit that contains a capacitor? What laws, etc. cause the voltage to trickle down and the resistance to be at that value?

Note: I literally just picked out a diode and a capacitor from a big pile of mixed components. I do not know how many farads/voltage drop they have.

simulate this circuit – Schematic created using CircuitLab


texts: Finding voltage across inductor in steady state

texts: I am uncertain about the voltage drop I got across the inductor because of its extremely small magnitude compared to the voltage source. Was my procedure correct or were there any flaws in my calculations?


texts: How does the mobile 3.5mm audio port work, and Can I light a LED from it?

texts: I am trying to do this, light a LED from the headphone wire(mobile) but it seems it gives ac in there, I don't have much idea, please help.


texts: Half Precision Floating Point in Systemverilog

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I have a 16 bit vector defined as:
logic [15:0] x;

In my simulation I want to assign x a half precision floating point number.
For example: 7.42
Is there a simple way to do it ?


texts: Does Switch current rating matters if its connected to ground wire

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I am designing a pcb with an SMD switch. Usually my circuit needs 200mA peak current. But I am putting a 25mA rated switch on the ground line.
Now according to my knowledge if I was placing this switch on Positive supply then I should be using at least 250mA rated switch. But on ground line of the battery it shouldn't matter ?


texts:
In a hobby project I am using shielded cable to connect capacitive sensor's electrode (see https://electronics.stackexchange.com/questions/189916/capacitive-touch-not-working-at42qt1011 ) to the AT42QT1011 (there are two cables ending with electrodes going in separate directions). Usage is proximity (millimeters), electrodes are insulated.

However, I left the shield disconnected (using only wires inside) as connecting to ground will make strong capacitive coupling with the ground - something which will render the sensor useless.

The question is, where to connect the shield? It is not particularly annoying that IC senses thru the shield, but what is the right thing to do?

(I have already settled on using particular cable, but may be there are better choices for cabling capsensors?)


texts:
I want to measure the conductance per unit length of a transmission line consisting of two parallel wires. Below you see a possible set up with an ohm meter and the transmission line.

Would it be possible to measure a resistance between the two wires?
If yes I could take the reciprocal and determine the condutance per unit length.


texts: What type of electronics is typically used to interface between PCs and custom hardware?

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I have tried to make this question acceptable for StackExchange, I am not looking for buying advice, just either examples of hardware that could have been used or the name of types of devices I should be researching.
I am very interested in automation and robotics but so far everything has been over my head in regards to my basic electronics knowledge.
I see in many places online like in this video on YouTube Link that often in the cases where vision is used the processing is done on a PC and that controls the hardware.
What is the name of the hardware that interfaces between the motor drivers and limit switches etc and the PC? I'm assuming for speed the interface would be USB or ethernet.
What are some examples of hardware that could have been used or what is the collective name of such hardware?
What is the name of the topic/category of technology I should be researching?


texts: How do I identify which point is Live and which point is Neutral of a 2-pin plug?

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I have a 2-pin plug that was not label which is Live and which is Neutral. I do not want to damage the electrical device and was wondering what should I do in order to test and find which point is Live and which point is Neutral?

The 2-pin plug look something like the following:


texts: heating element for miniature working oven

texts:
Please don't laugh but I am building a small working oven for my daughter and need a heating element that can heat it from 70 to 220 degrees celsius via a thermostat.

I've found this heating element http://uk.rs-online.com/web/p/ceramic-heating-elements/3762795/ (ceramic, 230V, 500W, 122 x 60 x 31 mm)

and this thermostat http://uk.rs-online.com/web/p/products/7334726/ (230V, 16A)

but am not sure these are suitable and would work together. The oven will measure about 15cm wide x 8cm hit x 10cm deep but I don't have to stick to this. Any help or advice would be amazing. You're laughing aren't you? :)


texts: My previous theory was wrong, so why does this work?

texts:
Hi I am new to electronics, and I have made a light tripwire using an Arduino Uno. I made this on the idea that electricity follows the path of least resistance, which I now know to be false (https://physics.stackexchange.com/questions/5670/electricity-takes-the-path-of-least-resistance).
False or not however, my tripwire works exactly as I would expect it to.

I programmed my board to sound an alarm if pin 2 reads low voltage
I thought it worked because if the photoresistor has less resistance than the resistor, then it would read high voltage and vice versa. So can anyone explain what is happening?

simulate this circuit – Schematic created using CircuitLab


texts: pci express connector mechanical feature

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What is the overhang on pci express connectors for? Is it for a rarely used board latching feature?
I am referring to the feature being pointed to in this picture.


texts:
If a small signal electronic load is designed for normal operation by using say 1.2 V 630 mAh battery and if the same battery is replaced with say 600 mAh or say 700 mAh rating battery, does it affect the normal operation of the load in anyway?

Ignore that the battery may deplete fast or slow based on the capacity.

What factors go into the design consideration that this load should operate with say 630 mAh batteries?

Just hypothetically if I have say 1.2V 600 mAh battery and load demands say 630 mA of current at a time, will 600 mAh capacity battery would be able to provide it or will it fail?


texts: Embedded system for image processing project

texts: Is it possible to do image processing (to extract numbers and text) using a microcontroller? If not, what are the alternatives to do this task?


texts:
The BA3121 is an audio (ground loop) isolation amplifier. In the datasheet there is no simple pinout picture with names of the pins, so I draw this pinout picture by following the block and the circuit operation diagrams. It takes me some time to do this (i am not an expert).

Before I try/continue, I want to be sure my findings are correct. Is this okay?

I have also some doubts about the pin order because mostly, the 5th pin is the upper-right pin. What is Vm1 and Vm2 in the schematics, what is "Vm" and why is it called "Vm"?

The pictures I have used to come to this:

You can find the full datasheet here:

BA3221 datasheet on marutsu
BA3221 datasheet on datasheet catalog (older one?)


texts: Motor for precise low speed motion but also capable of high speeds

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I'm trying to design a system that should rotate at up to 4000 rpm when needed but also be capable of precise (hopefully sub degree) positioning at under 100 rpm or less. I have an absolute position encoder for closed loop control. The load on the motor is very small (a thin piece of plastic).

What I've tried so far:

A hobby BLDC motor with an ESC. This works perfectly for high speeds but I haven't been able to get the ESC to go slower than ~1000rpm.
A stepper motor works perfectly at low speeds and micro-stepping + the encoder give great resolution. However I haven't been able to get a standard NEMA 17 stepper to go faster than 200rpm at 12V even when accelerating slowly.

These are an order of magnitude off from what I want in terms of speed range.

Some possibilities I've thought of:

Gearing down the BLDC. The downside is that the maximum speed will also drop proportionately and we are back to needing a motor with a high speed range.
Gearing up the stepper motor. This would reduce the effective resolution unacceptably while increasing speed.
Controlling the BLDC manually without the ESC. I'm not sure if I can get an average hobby motor to run slow and smooth even if I found an appropriate controller.

What is the best way to solve this problem where I can have precise control at low speeds but also the possibility of high speeds when needed? Is there some other type of motor or way to control these motors that can give me what I want?


texts: I'm working on a project with lots of op amps and so far had no problem but this one is driving me nuts. I need a 1:2 non-inverting amplifier which I built on breadboard but doesn't work as expected. The circuit is trivial, I tried different op amps (LM741,TL072,LM358), use a rail-splitter or just a voltage divider for the bias DC, with our without the DC decoupling caps and yet it doesn't work. It seems that negative half of the signal is gone (yellow being the output signal while the incoming signal is from a signal generator). Thank you for your help in advance!


texts: Mechanically and electrically controlled mains switch that preserves mechanical control without power?

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Is it possible to build a battery powered circuit that switches an electrical load (e.g. lamp), controlled both mechanically with a physical switch and electrically with a relay and preserve the mechanical control when the battery
dies.

The only way I can think of is a mechanical relay that is normally closed, but it will be impossible to power it from a battery for a reasonable amount of time.

simulate this circuit – Schematic created using CircuitLab

The neutral wires are inaccessible from the control circuit.


texts:
simulate this circuit – Schematic created using CircuitLab

Essentially my goal is to measure Node A and feed Node C into the arduino for further measuring.

What I attempted was use a buffer to not interrupt the amplifier circuit and add a DC blocking cap at the output of it, however this caused me to create a HPF and DC is still on the node as well. Is there a way just to stop the DC offset at Node B? Thats all I wanted to do.


texts: Regulating AA to 5V and achieving high efficiency

texts:
I'm trying to regulate a single AA battery to 5V for charging a USB device.

I know even at perfect efficiency, it won't provide much juice (1.5v * 1500 / 5v). But what is the expected efficiency for stepping up to 5v from 1.5v? Is 80pc achievable?

Are there other issues one should worry about in designing application?


texts:
I'm thinking of buying this battery:

As you can see, there are no solder lips. I'd like to add them myself, but don't know if that's a good idea. Is it possible to solder lips on a battery yourself? What equipment would I need? Are there any safety issues that I should be aware of, and how can I make this secure?


texts: I'm having trouble understanding SPST terminology

texts: Before someone LMGTFYs me, let me get this straight: I HAVE DUCKDUCKGO'ed this already, but I still cannot understand what switch 'pole' and 'throw' mean. I really just need a clearer explanation of switch terminology please!


texts: When I'm using a logic gate (let's say AND) in a schematic, which symbol should I use: the AND symbol or the IC symbol (the 4081, for example)? Or in the case of flip-flops, should I use the flip-flop symbol or the IC symbol?


texts: Is it possible to make a small computer from scratch using Intel processors? I am not talking about any advanced version like i7 or anything. Just 80236 or any old processor like that.


texts:
I have some old tapes (the compact cassette variant) and an old Technics deck. I want to digitally archive these tapes as best as I can.

The original deck is from the late 80s and contains a standard playback-only 180 ohm DC resistance stereo playback head with one common wire (so 3 wires total). Since the original deck sounds pretty bad by today's standards (lots of noise and bad dynamics) I want to replace the analog signal path with something more modern. There is not much information available on the subject, most of it deals with stupid things like tube tape preamps or other absolutely inaccurate forms of amplification. I know that tapes themselves don't sound great, but I want to preserve basically everything you can reasonably get off of them to throw them out afterwards.

I explicitly don't care about IEC equalization or Dolby decoding, or any hardware-level noise reduction (other than noise that comes from the signal path itself obviously) since I will do that in software when I actually need the tapes in playable form.

My tentative design currently consists of two LT1115 differential amplifiers (one for each channel) feeding a single AD1871 two-channel 24bit Audio ADC. The LT1115 are going to run off of regulated and filtered +15V and -15V rails, the ADC has its own regulated 5V rail (and a 3.3V digital rail). I'm open to swapping these components for better ones, this is just what I came up with.

I'm not sure about what layout I need on the analog side. Can a coil with three wires (one common one) even reasonably be treated as two differential inputs (since they shouldn't really share a common wire)?
Do I need any additional components in the analog path like a bleeder resistor for the coil charge or some form of matching or clamping?

I'd really appreciate it if somebody explain the analog behavior of tape head / inductor amplification.


texts:
I built up a LM317 power supply which is working great.

I have moved it into a large case as I am now powering it off 240VAC (fused) down to 18VAC then rectified into the power supply. Which is going well. I also put a much bigger heat sink on it (1.4C/W). The plan is to set up another one in there as well and have dual variable supplies.

Now the question is should I connected the ground pin off the 240V connect to the case? The case is a 19" rack mount. It is aluminium?

I am pretty sure that is what most people do but thought I would ask. It would stop the case from becoming live if something shorted to the case would it not?


texts: Is there test data for 120V receptacles exposed to continuous overvoltages?

texts:
Part of my job is to investigate fires and electrical damage. I've seen a case in a residence where a fire supposedly started in the area of an empty receptacle, and the building neutral connection was bad, resulting in all sorts of voltage fluctuations between the phases. That leads me to ask this question.

I understand that UL 498 involves testing receptacles for withstand of voltages over 1000 volts, but that this test is only for a limited number of cycles. Is there test data out there for 120 volt receptacles exposed to 240 volts for weeks at a time?


texts: Unable to find connector in eagle library

texts:
I am designing a PCB in Cadsoft Eagle. I need to connect this type of connector:

Image Source

But these connectors are not available in eagle libraries.
Does anyone have any idea about how to use these connectors in designing PCB.


texts: How to attenuate a cheap MP3-player speaker?

texts:
I have a cheap single-chip MP3-playing speaker. The kind you you get off eBay for $10. I want to make the output quieter (so I don't always have to adjust the digital volume controls).

The amp is a LTK8002D Class AB Audio Amplifier

I want to do this in a way that doesn't damage the circuitry. I only have basic electronics knowledge.

Should I do this with a potential divider? If so, should the total match the measured impedence of the speaker? The spec sheet says the speaker is 4 ohms.

Or should I do this with an inline resistor?


texts: AVR setting certain PWM frequency and duty cycle is not working right

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I am prototyping a simple LED dimmer on an Arduino Uno (Atmega328p) and I have issues with the PWM frequency and duty cycle I am trying to adjust.
To get a frequency of 200Hz flat I am using the CTC mode and I used the formula in the datasheet (OCR2A = (F_CPU/2N200Hz)-1) to calculate the upper output compare register (OCR2A). It's 38 in my case.
The lower output compare register (OCR2B) is being controlled by an ADC input.
The ADC is working fine. I checked it with the serial monitor. So that part of the code can be ignored.
My main gripe is the frequency. According to my cheap handheld oscilloscope the frequency is stuck at 60Hz even if I change OCR2A. I can't explain why.
Then there's a problem with the duty cycle. If OCR2B is at 6 the duty cycle is at ca. 13%. If OCR2B is at 37 the duty cycle is close to 0%. I expected the duty cycle to be much higher the lower OCR2B is. Why is this not the case?
#define F_CPU 16000000UL

#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>

void setup() {

    sei();
    DDRC = 0;                      // Input for ADC
    DDRD |= (1<<PD7);         // PWM Output
    ADMUX = 0;                  // use ADC0
    ADMUX |= (1 << REFS0);    // use AVcc as the reference
    ADMUX |= (1 << ADLAR);    // Right adjust for 8 bit resolution
    ADCSRA |= (1 << ADEN)|(1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0);  // Enable the ADC, 128 prescale

    TIMSK2 |= (1<<OCIE2B)|(1<<OCIE2A)|(1<<TOIE2); // enable Timer/Counter Output Compare Match B Interrupt, enable Timer/Counter Output Compare Match A Interrupt, Ebable Timer/Counter Overflow Interrupt
    TCCR2A |= (1<<WGM01); //CTC Mode enabled
    TCCR2B |= (1 << CS22)|(1<<CS21)|(1<<CS20); //prescale: N=1024
    OCR2A = 38; // 200Hz PWM (upper threshold of timer compare register), OCR2A = (F_CPU/2*N*200Hz)-1
}

void loop() {

  ADCSRA |= (1 << ADSC)|(1 << ADIF);    // Start the ADC conversion -> ADSCRA = 0101 0000

  while(ADCSRA & (1 << ADIF) == 0); //ADSCRA = 0101 0000 & 0001 0000 = 1 ---- 0100 0000 & 0001 0000 = 0 -> conversion finished

  OCR2B = ADCH*38/255; //scaling of OC2RB, since OC2RB (lower threshold of timer compare register) must not be higher than OC2RA!

}

ISR(TIMER2_COMPA_vect) {
   PORTD &= ~(1<<PD7);
}

ISR(TIMER2_COMPB_vect) {
  if (OCR2B < 5){
    PORTD &= ~(1<<PD7);
  } else {

    PORTD |= (1<<PD7);
  }
}


texts:
It seems to me that if you try to solve for an Op-amps output (with negative feedback) discretely (i.e. iterating), you never reach equilibrium. Rather, you find the output moves further and further away from the desired value.

This leads me to believe that the output of an Op-amp does not "snap" to any value, but rather continuously rises or descends (albeit extremely quickly), so it passes it's point of stability and reaches equilibrium. Not sure if I've explained this well, but is this along the right lines?


texts: How is it possible for this circuit to continue functioning correctly?

texts:
A circuit uses the RN5RT33A voltage regulator to generate the 3.3V rail.
According to its datasheet the abs. max output current is 150mA, typical output current is 60mA.

There's an add-on board that feeds on that 3.3V rail and draws additional current from the regulator. I've measured the approx. current used by the add-on board and it was why of 310mA max and around 200mA most of the time.

How is that possible? It seems that would exceed the ratings of the regulator, however the circuit seems to be working fine.


texts: Open-loop frequency response for an op-amp

texts: I want to know what is the ideal circuit to measure open-loop frequency response and why?I have seen the typical open-loop frequency response curve for an op-amp a lot of times. But when I try to plot it for my circuit simulation even though it resembles the shape, it varies a lot with the input signal. I am simply sending a small AC signal with no feedback and plotting output. What will be the ideal input AC signal to plot it assuming I want to use this later for Differentiator design assuming I want to use an inverting op-amp for it.


texts: Why would an induction cooker periodically click when idle?

texts:
A typical induction cooker has output power adjustment which is usually implemented in two fashions. Higher power settings are "continuous" - the cooker outputs say 1200 watts all the time it is switched on. Lower power settings are "switching" - the cooker would claim its power is 300 watts but it actually cycles between say 800 watts and no power. The second mode can be confirmed when boiling previously hot water at lower power settings - when the cooker inductor is actually on the water starts boiling and when it's off the water suspends boiling and water cycles between boiling and not boiling all the time.
So there're several cookers of different models and they all show the same behavior. When a lower power setting is selected the cooker cycles between two phases. In "on" phase the cooker produces only fan noise and causes water to boil. In "off" phase the cooker produces fan noise and also periodical clicking sounds when are similar to some relay switching or something like that and in this phase water does not boil. The clicks sound all the same no matter which cookware is used so it's likely not from magnetic fields interacting with the cookware but from the cooker electronics. Clicking sound rate is roughly one click per second during each "off" phase and no clicking sound occurs during the "on" phase.
I guess this is a well known way to implement the cycling between "on" and "off" phases.
Why would those clicking sounds be produced when the cooker is in "off" phase? What would cause them?


texts:
I have a DC motor (controlled by an arduino MEGA) and I plan to move some 3D Printed gears and a pulley.

I have a problem with the belt jerking when power is applied to the motor through the arduino and I'd like to know what type of formulas I can use to modify the function that makes the motor calls.

I found a guy on here who has a similar question but his is for stepper motors, not for DC. I see his approach and wonder if I can use this as well? (I just don't want to try it and break something)

Smooth A Motor Movement

I would comment on his post, but I guess you are not allowed to ask question on other people's posts, so I have to do my own to get insights on how to impliment something like that for my application.

I'm using this belt and this motor


texts: can signal ground be carried in the connector shell?

texts: I have a cable with 6 pins but I have 6 signals and I don't have space for the signal ground. If the shell is continuous from end to end, would it be fine to use that as the signal ground?


texts: I have a small doubt. Suppose I transmit just 2 square pulse with frequency of 100 MHz over a wireless channel, will it spread in the time domain when received by a wireless receiver. In other words, a 100 MHz square pulse will have a High for 5ns, and then low for next 5ns and then again a High for 5ns. At the receiver, I receive the same pulse attenuated and which looks like a guassian distribution. But will the difference between the 2 peaks be still 5ns or it may change?


texts: The voltage reduced variation of battery in the electrical appliances we used

texts:
There are lots of battery in our electrical appliances,for example,laptop, remote control and mosquito swatter,etc.As we know,the battery we used can be a voltage source in that appliance,that is, a VDC in our IC simulation.Normally,our VDC almost doesn't reduce,ignore 10% error,but the battery voltage will reduce with the time we used.So i am a little confused with the voltage reduced variation of battery.I will provide two possible situation for the voltage reduced variation of battery,but i don't know which is right.

Set the battery is 1.8V for full charged,and can use for 10 hours.

1.The voltage reduced variation and time are almost linear decrement,that is ,if the voltage will reduce 0.18V/1 hour,then after 1 hour,the voltage should be 1.62V ,and the voltage should be 0V after used for 10 hours.

2.The voltage will be a constant,almost 1.8,for using 10 hours,but after 10 hours,the voltage will reduce rapidly,but won't reduce to 0V,take 0.5V for example,and 0.5V can't provide(active) the IC in the electrical appliances,so we say the battery is dead.


texts: 415V 3 phase supply monitoring device has a 240V rated relay. Details inside. How to use?

texts:
i would like some help understanding the ratings of a relay. It's a long post. Please bear.

I have a 3-phase voltage monitoring device (called device from now on), that monitors phase reversal, outage, assymetry etc... The device has a relay with the following ratings:

  Relay Output : 1 C/O
  Contact Rating : 5A (For ‘NO’) & 3A (For ‘NC’) @ 250 VAC / 28 VDC (Resistive)
  Utilization Category:
  AC - 15 Rated Voltage (Ue): 120/240 V, Rated Current (Ie): 3.0/1.5 A
  DC - 13 Rated Voltage (Ue): 24/125/250 V, Rated Current (Ie): 2.0/0.22/0.1 A

This device is used to control a DOL motor starter. The starter has a contactor coil which comes wired by default between L1 & L3.
L1 straight to the coil (terminal A2),
and L3 goes through
T1-start button-T2,
T2-wire-T3,
T3-stop button & thermal overload-T4,
T4-coil (terminal A1).

Now, the easiest way to wire the device is to remove the wire between T2 & T3, and connect T2 to the common (15) on the relay and T3 to the NO contact (18). So when the supply is normal, the device acts just like the original wire between T2&T3. When there is a problem in the supply, the relay opens the NO contact, and the contactor coil is de-energized. The contactor coil is 57VA when closing 13VA when closed.

Now my problem is that the Line to Line voltage is 400V +/-5V. The monitoring side of the device is rated for this voltage (415V). But the relay that breaks the line for the coil is only rated for 240V AC from what i can understand. So, is it safe to wire it in the way i mentioned? What are the alternatives?

Please reply for any clarifications, since my terminology might be difficult to understand.

Thanks in advance.


texts: Will connecting a 78L05 or 79L05 voltage regulator backwards fry it?

texts:
I got a SainSmart digital oscilloscope kit for christmas, and put it together according to documentation I found on the Amazon.com listing for the item.

The markings on the board directed me to connect the input pin and output pin opposite of how they should have actually been connected. That is, it was receiving 9v to the output pin instead of the input pin, and the input pin was connected to where the regulated 5v output was supposed to go. I discovered this by nearly burning my fingertip on the overheating voltage regulator after plugging in the 9v power supply, and then looking up the voltage regulator's datasheet and comparing it to the board diagram.

I removed the voltage regulator, turned it around, and soldered it back in place. When I plugged in the power supply again, the regulator got hot again, and I still didn't get the expected 5v at the output. Is my voltage regulator fried?

(Note: it's either a 78L05 or a 79L05 - the board has one of each and I don't recall offhand which one was the one I was dealing with.)


texts: Current of inductor in parallel to resistor

texts:
When a resistor and an inductor are in series, by simple writing down all the voltages and using integral, the current of the inductor could be calculated.

simulate this circuit – Schematic created using CircuitLab

\$ v - IR - L (dI/dt) = 0\$

\$ I(t) = (V/R) * (1 - e^{-tR/L}) \$

But in the circuit shown below, writing the voltages doesn't do much help since when I use integral on the equation, the charge of the inductor appears (integral of current by time) which I don't have any answer for and don't think is part of the equation. So how should I try to find the formula for the current of the inductor?

simulate this circuit


texts:
I'm trying to understand precisely input leakage when a GPIO is configured as an input. So I read some MCU datasheets, here is kinetis MK20 datasheets
on p15/16 are given input leakage currents.

I've also read this document about input leakage measurements. First cause of input leakage are protection diodes.

Vil/Vih is maximum input voltage to read a low/high level on digital input.
We can see, input leakage has maximum values when Vil < Vin < Vdd, in this case when Vdd=3.3V we get ~15µA input current.

from theory protection diodes are mostly responsible of leakage current, here is a schottky diode datasheet, in figure 4 is a reverse leakage current vs voltage figure. As you can see current increases with voltage. So, for MK20, when voltage Vil < Vin < Vdd, a current goes from input to GND threw reversed diode, its name is Iind. But, why do we have min leakage current when Vin = Vdd and much higher current when Vil < Vin < Vdd ?

In note (7)

  Examples calculated using Vil relation, Vdd, and max Iind :
  Zind=Vil/Iind. This is the impedance needed to pull a high signal to a
  level below Vil due to leakage when Vil < Vin < Vdd. These examples
  assume signal source low = 0V

I'm not sure I've fully understood this note. When we apply Vil < Vin < Vdd, we can read on Input a low level. It means if we have Vil < Vin < Vdd, for example Vin = 3V applied with an output impedance of 100k on digital input, we will have a voltage divider on Input. So on Input we will have 3V x 50/(50 + 100) (voltage divider) = 1V => low logical level will be read.

Am I correct?


texts: I am building a portable bluetooth speaker. I am using 4 18650 Li-Ion batteries and using 4S 14.8v BMS/PCM charge/discharge protection board with balancing. This board works great, but the challenge is when the board goes into "protection" mode you have to apply voltage to it to launch the device. This means that I have to connect speaker to my 15v power supply, close s1, s2 and s3. Once I see that the amplifier is working I can unplug the power supply and use the device as portable running on batteries. This is a requirement even when the batteries are fully charged (please see diagram). Is there a way to avoid having to apply power supply voltage to launch this BMS? If not, are there other boards that have better design for this application?


texts: Pspice software - simulation result of boolean circuit not as expected

texts:
I am trying to verify a boolean expression (AB +AC+AD') for which I constructed a circuit diagram, but the output simulation window shows 2 red lines. I am pretty sure my circuit is correct.
Circuit:

Simulation results:


texts: Does a voltage source produce current on an open branch?

texts: I am supposed to find the Thevenin equivalent of this circuit however the branch with the 30V source is confusing me. I know that if there was only a resistor in that branch then no current would flow in that branch. However is that still the case when there is a voltage source there? I think that there will be no current in the branch because there is no return path but the 30V will still add to the open source voltage. Is my logic right?


texts: Meaning of Input Leakage Current vs Shutdown Current and Quiescent Current

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I am looking at an IC load switch that has values for Quiescent Current, Shutdown Current, and Leakage Current.   My understanding is that Quiescent Current is current drawn by the IC in the "on" state and the Shutdown Current is the current drawn when in the "off" state, but I don't know what Leakage Current means and how it affects the total current picture.  In other words, to calculate the total current used in my system.
For example, I figure I need to take the duration in shutdown state * shutdown current + duration in ON state * quiescent current but I don't know where Leakage Current fits in this calculation and what it means.  ie, is Leakage Current included already in Shutdown Current or vice versa or somethng else?


texts: Charging a series of Nissan Leaf Li-Ion Batteries

texts:
I have an electric motorcycle I built out of a 1995 Suzuki GS500e.

Right now it has four Optima Yellow Top AGM batteries in series giving me around 48v of power.

I want more range out of the bike without sacrificing performance, so I have been looking into Nissan Leaf Li-Ion cells. They're cheap, small and stackable.

At 7.6v each, I'd need 8 of them to get me to where I am, and as I hone in on my desired range, I will just add batteries (my AXE controller allows scaling).

Through all of my research, I can't figure out the best way to charge them while connected in the array (safely). Presently, I have an on-board charger and I can plug in at Level 1 EV charging stations, i'd like the same for the Leaf batteries.

What would I need to do to accomplish this?


texts: What does it mean to short circuit a transmission line stub at a specific frequency?

texts:
I'm currently designing a  microwave FET mixer right now, and I have to short-circuit the FET's drain at LO frequency and its harmonics. I've checked the "stub" article in wiki, and it says that the resonant frequency of the stub is w0=piv/2l. So i set the drain stub's length to this value at the software to short circuit it at the LO and its harmonics. It is enough for it, or should I adjust other parameters?
Or if it's completely the wrong way, how could i set it to became short cirtuit?


texts:
I am trying to understand how laser show galvanometer systems like this one create high-resolution movement, and generate drawings of reasonable precision (w.r.t. minimum beam angular-deflection step size) on a surface several feet away.

The Wikipedia page has very limited information about the modern version, although a paragraph claims high-speed mirror galvanometers are used for laser ablation, marking, etc., which are of course high-precision applications.

Given laser show devices are so popular, but the documentation a bit lacking, I would appreciate an explanation, especially of the closed-loop part which these laser show "scanners" claim to contain.

Do they use a stepper motor (and just claim it's essentially closed loop), or do they have a standard DC motor with a magnetic/optical encoder of some sort?
Also, what kind of angular resolution is a system like the above linked product, typically capable of?

As may be clear from these questions, I am trying to see if it would be apt to repurpose one of these for my own project, where I need to attain laser-marking at approx. 50-75 microns resolution at a few centimeters away (unfortunately, physical constraints prevent use of a gantry system that might be seen in 2D plotters/3D printers).


texts:
I have this Philips One Blade trimmer (disassembly video) and I have probably by mistake tried to charge it with charger from the older Phillips shaver which had almost identical connector but 15V instead of 4.3V used by this one - the result is it can't charge.
I opened it and there is one burned component on the PCB, but I can't identify what is it (I am not much of electronics expert).

I would be glad for help with identifying that component or a replacement alternative to repair the trimmer.

Solution summary:
The part was diod in SOD323 package. I replaced it with 1N4148WS-SOD323 and it seems to work. Thanks for all help.


texts: How to transmit packet size grater then 64 Bytes through cc2500 chip?

texts:
I am interfacing cc2500 chip to controller PIC18F67K67 at target device side.My host side have cc2511 chip which receives data.

I have to transmit packet of size 247 Bytes form cc2500 to cc2511.

My question is how to transmit data grater then 64 Bytes (FIFO size)  from cc2500 to cc2511???

I read datasheet both device but not getting help from it.


texts: What maximum number of buttons i can connect to Arduino (100 buttons and more)

texts: Is it possible to connect something like 100 buttons to one arduino nano, by using this classic method (or other possible cases)?


texts:
What does this schematics symbol mean?

Taken from here.
I got the PCB and it's not a button.


texts: I found this CMOS circuit in my textbook. It says that when input voltage is 0V, the output voltage is 0V, and IDN and IDP are both zero. I think that the output voltage is 0V due to some form of symmetry. However, I could not understand as to why IDN and IDP are both zero. Could anyone please explain? Thanks.


texts: Integrated Circuits for Signal Switching

texts: Sometimes I need to switch digital signals between microcontrollers or devices. For example I have a serial device and I want to control to which microcontroller it is connected per digital pin. So must of the times I used a relay. But relays are too big and need high currents. Are there small ICs for digital signal switching or multiplexing. For example for Serial, I2C, SPI or USB? Or could I use a normal transistor for this job?


texts: What electric part is on this manhole cover?

texts:
Here's a photo of a manhole cover

The letters form the word "ТЕЛЕФОН" ("telephone" in Russian in ALL CAPS).

What is on the picture in the center? Perhaps it is some part that should be associated with communications but I have no slightest idea what it might be.

I've Googled a lot and found that this image is a logo of a USSR state organization responsible for communications which acquired all the assets (logo included) of Svensk-Dansk-Ryska Telefon AB (rus Шведско-Датско-Русское телефонное акционерное общество) telecommunications company that used the same logo.

More Googling finds this one century old logo of a Stockholm telecommunications company that has the same image yet much simpler and with carefully depicted main details.

So far I've seen various explanations of the image, including a receptacle and a candlestick telephone earphone (the earliest telephone design had a fixed microphone and the earphone had to be held next to ear). However none of the claims are backed with reputable sources.

What is the electric part on the image in the center of the cover?


texts: Where can I find test labs for FCC and other unintended radio emissions testing?

texts: Where can I find labs where I can pre-test or certify an electronic product intended for sale, according to FCC rules?  I've searched the FCC website for a list of certified labs, without finding such a list.


texts: Measuring Active power through current sensors

texts:
i want to measure the AC current - with 220 V AC 50 HZ at home -
i will use a current sensor then find the power factor through comparing the signals of the V and I then find the power then i integrate to find the Energy consumed by using micron controller.
My Questions
1- What are the considerations for the current sensor?
2- do they produce an AC voltage exactly proportional to the waveform of the current? i watched the video here , i think the answer is yes?
3- can you recommend some as the only i found are from here 1, i don't know if they are are reliable or not?
4- is the total algorithm right or there are problems?
Thanks.


texts:
I want to make a tiny led glow for 10 minutes once charged by induction. I want the entire PCB not greater than 20x20x5mm. Is it possible? I have come up with the following circuit, I don't know if it works are not but my idea is to store energy in capacitor and inductor when the switch is closed and make them discharge through LED when the switch is open. You see, LEDs of electronic devices glow for a while after they are turned off. I have not put accurate values as I don't know what capacity of components are available in the market. I don't want to use a battery as I want a very long lifetime. I am sorry if anyone gets offended for asking this without practicing electronics.

simulate this circuit – Schematic created using CircuitLab


texts:
I am very new to AVR and even for coding of micro-controllers. I wanted to shift out 32 bit data on SPI from a Atmega16 to a 32 bit shift register. The shift register in not an SPI compatible device. But still hope to use to get the fast transmission.

Since the AVR is having only 8 bit data register, only one byte of data can be written on it. So I need to shift our 32 bits of data. I am able to do the same like making SS# low->load first byte of data->wait till transmission complete->make SS# to high to latch the data. I am doing it four 4 times and getting the 32 bit output. But the issue here is the clock is not continuous, for each byte there is a delay between the clock burst. In this this case the external shift register will not get the 32 bit continuously since for every byte I am doing the SS# low and high. I need to get the complete data packet continuously with out any break. I am digging further into this to resolve.

It would be helpful for me in the meantime if someone can share any idea.

Regards,
Prabhu


texts:
I need to short-circuit a power source using a microcontroller to measure the short-circuit current capacity (less than 10A). So the impedance of the short circuit should be as low as possible.

I was using a 5V relay commanded by a BJT transistor and it works very well.
But for space reasons I would like to test other options, like using a MOSFET transistor working as a switch.
I tested with the logic level NMOS IRL540N as shown in diagram and it worked fine. Putting 5V at the gate closes the short circuit with about 36mΩ resistance.

But the problem is when the power supply is connected wrongly with reverse polarity the NMOS always conducts, even with a low microcontroller output.
I don't understand why it conducts as VGS remains null even with reverse polarity connected.

How can I protect the MOSFET to be always off when reverse polarity is connected to drain-source?

The power supply could reach up to 25V. Is the MOSFET always secure?
The absolute maximum rating for Gate-to-Source Voltage is 20V, but in this application VGS is always lower than 5V.

simulate this circuit – Schematic created using CircuitLab


texts: How do we design a LISN circuit for DC-DC converter?

texts: I am trying to understand about LISN (Line Impedance Stabilization Network). When i research online, i find different LISN circuit based on the standards and specifications. On what criteria i should choose the circuit ? What are the conditions should i take into mind when i draw a LISN circuit ?


texts: Home-made impedance meter: what's the difference between voltage divider and active filter methods

texts:
I'm dealing with the measurement of impedance sweeping the frequency from 0,1Hz to 100KHz. On the web I found many methods but the most quoted seems to be the one which uses an operation amplifier in inverting low-pass filter configuration:

Z represent the impedance under test. In this configuration, we can find the module and phase of Z comparing the input and the output of the filter.

Another simplest method I found is the common voltage divider:

Z is the impedance under test again and its module and phase can be found again comparing the input and the output signals.

Now, I know that the first method which uses the opamp should be the better choice since it's used in the most Z-meter, but I don't understand the real advantage using that one.

Can anyone light up my mind?


texts:
I am finding it confusing in defining various clock domains in the design. I did search over the Internet but I didn’t get a complete clarity on this.

In a certain FPGA (Actel ProASIC series) based design, I am generating three clocks – 48MHz, 24MHz, and 12MHz from an 8MHz crystal input using a PLL. Further, using one of these 3 clocks (48/24/12) I have to generate 8MHz, 4MHz, 2MHz, and 1MHz clock signals for using in a few of the logic modules.

My assumption is that since 48MHz, 24MHz and 12MHz are generated from the same PLL and are having a constant phase relationship, I can consider them as part of a single clock domain. And I can use a common reset signal synchronized w.r.t. 48MHz for resetting the flip-flops clocked by 48MHz, 24MHz or 12MHz. Is the above assumption correct?

For the generation of 8MHz, 4MHz, 2MHz and 1MHz clock signals I am using free running counters clocked at 48MHz (I could have used 24MHz also for this purpose, but 12MHz required fractional division to generate 8MHz out of it). I am confused whether the generated clocks 8, 4, 2, and 1MHz can be considered to be in the same clock domain as 48MHz. What should be the general rule in differentiating various clock domains?

Can I use the above mentioned reset signal for resetting the flip-flops clocked using 8, 4, 2, and 1MHz? Or should I generate separate reset signals for this purpose?


texts: Would having a DC-to-DC Step Up Converter Damage the L293D H-bridge IC behind it?

texts:
I recently purchased two L293D H-bridge Motor Controller from Adafruit (data sheet here), but after reading that the controller could only output a max of 600mA for a short time, I realized I had a problem. Due to the constraints of the Arduino that would be driving it, I can only get 600mA anyways, so I figured that I would need to use a DC-to-DC Step Up Converter to boost the voltage (therefore current) to run motors. However, I was worried that increasing the voltage after passing through the IC might damage it, and although I doubt it, better safe than sorry. Being two bucks a pop, would increasing the voltage after leaving the H-bridge, i.e., between the IC and the motors, damage the IC?

Forgive me if this is bad question, but I'm relatively new to electronics. :)


texts: Establishing ground truth in a particle filter experiment using compass and gyro

texts:
I'm working on coupling gyro and electronic compass for better accuracy of device orientation (using particle filters). I have one basic question, though: how do I establish ground truth in this case? I cannot use the compass readings alone, since the whole basis of my experiment is that the compass readings are inaccurate.

Would taking an average of a number of compass readings be a sufficient approximation? Is there any other idea, besides having a compass of "greater accuracy"?


texts:
I am planning on wiring 8 x 4-20ma 2 wire sensors to a PLC.
I would like to know if I need an individual 2 core shielded cable for every sensor or, if I can simply run all the sensors in a single multicore shielded cable (16 core).
Kind regards
Pablo


texts: Stepper Motor Accel/Decel Ramp for Fixed Frequency Input

texts:
I have a reasonable working knowledge of electronics but am trying to find a solution to a puzzle I've come across and have not been able to find a complete answer. This involves a stepper motor and I have not worked with these before, but understand their principle.

I am trying to drive a stepper motor in the following manner. I have an encoder that is running constantly and generating a frequency that is approximately constant. This will drive my motor at a speed proportional to the encoder output frequency. I want to start the stepper motor on a signal from a sensor and stop it on a signal from a second sensor.

I've found details of how to drive a stepper motor, using ICs such as the UCN5804 series.

I've found material on the need to apply ramping to the speed of the motor on startup and shutdown and I've found a circuit on this site that will generate a trapezoidal profile using a 555 timer.
(https://m.eet.com/media/1144287/203799f1.pdf)

It seems to me that I would need to use such a circuit to ramp up the motor, then switch over to  my encoder signal to drive it, then switch back to the 555 circuit when I want to ramp down. This seems a very cumbersome arrangement.

My question is, how can I ramp up my stepper motor, given that I have a continuous input pulse stream of approximately constant frequency?


texts: Are IC rail tubes sufficient protection for ESD-safe storage?

texts:
I've ended up with a collection of spare IC chips and am wondering what lengths I need to take to store them properly with respect to ESD.
Depending on their size they tend to come from the supplier in either a plastic tube or a cut length of tape which itself is packed in a silvered anti-static bag.
These plastic tubes usually have ESD-related markings on them but are not measurably conductive when probed with a multimeter either. Are the tapes/tubes themselves sufficient to protect contained components, or merely compatible somehow with the rest of an ESD-safe system (i.e. only just one "part of a complete breakfast" as it were)?
If I collect my "extra" chips into these leftover tubes at a grounded workstation, can I then treat the outside without regard to ESD precautions? Or do they need to go back into a silvered bag, the way they were shipped originally, before leaving an ESD safe environment?
Asking primarily as a hobbyist but would also be interested in the "proper" answer for production contexts.


texts: Is there an advantage to process EEG data as analog (vs digitized) signals?

texts:
Please note: Although this question mentions an electronic circuit depicting an EEG, I believe this is purely a bio-electrical question that is appropriate for this site, and should be answered by any battle-weary Biomedical Engineers that have had experience with EEG.

I stumbled across this DIY EEG Instructable, which is interesting and novel, but which has a number of drawbacks (from an EE perspective).

What surprises me most about this circuit is the constant amount of correction/filtering that the author is doing at each step:

Two 60Hz notch filters one at each "end" of the circuit, to reduce noise at a particular frequency (do we really need two?)
High pass filter for circumventing galvanic skin response
Low pass filter for waves > 30Hz
Yet another high pass filter
Op-Amp

To me, it makes sense to digitize the circuit upfront (by running the analog brain waves through an analog-to-digital converter, or ADC).

This leaves me feeling that perhaps there is some intrinsic/inherent value to EEG evaluation of analog (as opposed to digital) waves. So I ask: is there a compelling reason to tune/correct/filter raw analog brainwave/analog signals for EEG, or is it perfectly fine to digitize the waves and then process them?


texts: Need a help with adjustable DC power supply

texts:
I just purchased an adjustable DC power supply.

https://www.amazon.com/Variable-Eventek-Adjustable-Regulated-Alligator/dp/B07DQR177D

It has three terminals : "-"(black), "ground"(green) and "+"(red).

When I test it with multi-meter, there is no voltage between the negative rail and the ground rail. Same for the voltage between the ground rail and the positive rail.

When I connect the negative rail and the positive rail together, it works correctly.
However, this is not why I bought an adjustable DC supply with 3 terminals.

I bought it so that I can use operational amplifiers...

What would the purpose of this ground terminal?

Is there a way that I can use this adjustable DC power supply as I want to use it?


texts: It it possible to run 5V led strips with a 12V Power supply?

texts: I am working on a LED project involving 5V led strips. I did some calculations using the  WS2812B led strips and found that I need ~100W. I took the cheapest power supply available where I live but it delivers 12-24V. Is it possible to arrange the LED strips in a way that the voltage would add up to the output of my power supply?


texts: In Cadence software, I am trying to modify (W/L) for the CMOS transistors, I am using GDPK 180 library. Can I modify the length of the transistors to be different? or it should be the same for all transistors?


texts: Calculation of Initial Charge Deficit and Initial State of Charge

texts:
I am working on Simulation Model based Lithium-Ion Battery Development with MATLAB/Simulink. For the battery model, I need to define Intial Charge Deficit , which is a phenomenon which every battery undergo due to its default 'Self-Discharge' characteristic. So, ultimately i need to calculate - the charge which reduces due to this self-discharge initially and causes a minor change in the value of Rated Battery Capacity.
However, after reading several papers, I found that one way to calculate this is by the following formula - Q_initial = 0.5 * mean (Battery_Capacity) [where Battery Capacity is an array of capacity value measured at 3 different temperatures).
Similarly how to calculate initial State of Charge, after subtracting the self-Discharge value.
Please Clarify .


texts:
I have a 3W LED that the manufacture states that if I 'feed' it with 750mA it will 'live' 100,000 hours (Very good heat sink, mid ambient temperature, etc....).

Assuming this is correct and the manufacture knows what he is talking about, how will the lifespan of the LED be affected if I 'feed' it 800mA? 850mA? Will the lifespan will be shortened dramatically? Or 50mA isn't such a big deal?

I'm sure there is no straight answer but even a 'rule-of-thumb' will be good.
Thank you for your answer

Gilad.


texts: Why are electrical solders with antimony not more common?

texts:
The most common lead free electrical solder alloys are SAC305 (96.5%Sn, 3.0%Ag, 0.5%Cu) and Sn99 (99.3%Sn, 0.7%Cu), especially for hand soldering wire.

Small amounts of antimony (Sb) have been shown to improve the properties of tin-based solder. Most of these are mechanical (strength) benefits, similar to the benefits of silver while being cheaper. The most common electical solder alloy with antimony is Ag03A (96.5%Sn, 2.5%Ag, 0.8%Cu, 0.5%). It's still not as common as the above mentioned alloys in mass production, and is almost nowhere to be found for hand solder wire. So I question why this is.

Here are some advantages I see of the Ag03A alloy vs SAC305 (due to the antimony):

Increased wetting (probably, although 0.3% is more optimal for this)
Increased thermal fatigue resistance. [1]
Inhibits tin pest and other undesirable compounds.

And here are some more advantages that come specifically from replacing some of the silver with antimony:

Lower cost
Less silver oxide (which ruins the solder when heated for too long)
Reduced cracking

So why is this alloy not more common?
Some sources say that AIM has a patent on it, but according to this it only applies in USA and Japan. But isn't SAC305 also patented?


texts: PCB Crosstalk calculators... Center line distance or trace separation

texts:
I am still a beginner in this field, and recently I've learned about Crosstalk and Crosstalk calculators. I've tried the one on EEweb, Saturn, Ultracad and some others. Some of these calculators ask for Center Line Distance between traces (D) while others ask for Trace Separation (S). The formulas used are the same, I can say this because I've tried with D=S and I obtained the same results.

My question is, why do this calculators use S or D? I've searched here and on the web and read some Signal Integrity books but I find no answer to my question.

Thanks in advance!


texts: What is the effective equivalent battery capacity between Lithium Ion and Sealed Lead Acid batteries?

texts:
I was told by a battery salesperson that a Lithium Ion 100Ah battery is equivalent to a 260Ah lead acid battery bank. Is this correct? I understand that lead acid batteries should only be discharged to 50% so I would have thought that on this basis, Lithium Ion 100Ah would fall short of SLA 260Ah even if the Lithium Ion battery is able to be discharged to 0% SOC. Is the Lithium Ion battery technology more efficient such that Lithium Ion 100Ah is equivalent to SLA 260Ah?

Also I have read conflicting views as to how deeply Lithium Ion batteries are able to be discharged. Some literature states that they can be discharged to 20% SOC and other literature states that they can be fully discharged to 0% SOC. Which of these points of view is more accurate?


texts:
I'm trying to do simple SPI communication on STM32 Discovery, HAL lib is used. I'm trying to send some data via SPI1 and to receive same data on SPI3 (SPI1 = Full Duplex Master, SPI3 = Full Duplex Slave). For transmit polling method is used and for receive DMA circular. Communication is on 1 device (just one Discovery is used). Code stuck here:

  while(HAL_SPI_GetState(&hspi3) != HAL_SPI_STATE_READY){}

Can someone explain me why code stuck there?

uint8_t rxSpi[10] = {0};
uint8_t txSpi[10] = "123456788";
    int main(void)
    {
        HAL_Init();
        SystemClock_Config();

        MX_GPIO_Init();
        MX_DMA_Init();
        MX_SPI1_Init();
        MX_SPI3_Init();
        MX_USART2_UART_Init();

        if(HAL_SPI_Receive_DMA(&hspi3, rxSpi, 10) != HAL_OK)
        {
            Error_Handler();
        }
        while(HAL_SPI_GetState(&hspi3) != HAL_SPI_STATE_READY){}

        while (1)
        {
            if(HAL_SPI_Transmit(&hspi1, txSpi, 10, 100) != HAL_OK)
            {
                Error_Handler();
            }
            while(HAL_SPI_GetState(&hspi1) != HAL_SPI_STATE_READY){}
            HAL_Delay(1000);
        }
    }

If I just send data (receive initialize is commented), on logic analyzer I got this, basically there is missing small interval between two bytes.


texts: Need help understanding AVR ATMEGA / ATTINY timer mirrored output

texts:
I am trying to use Timer1 of Atmel AVR microcontroller, either AtMega328 as used in the Arduino, or the ATTiny85, to output two clock signals which are mirror images of each other. The frequency I am trying to generate is a variable 1 MHz to 2 MHz or more which are too high to do this using code to toggle the output pins unless I want to do almost nothing else in the controller. So I want to use the timer output directly on the associated pins. I am using GCC toolchain so not limited by arduino libraries or language.

Timer1 in the Atmega328 has two pins associated with it and I can get two identical 1MHz to 2MHz signals out of them. Though the datasheet seems to say I can get an inverted waveform, it is confusing me. I am also able to get two signals which are different duty cycles at 1 MHz, using the PWM settings with Timer1, but both signals go high at the same time, the shorter one goes low earlier. This does not serve my project. I do not even need the PWM pulse width variation, I just need two identical "clock" type signals of opposite phase, that's all.

I am not asking for anyone to write code for me to do this, I just need someone to tell me which mode / flags of the timer should give me a simple inverted waveform on one of the two pins associated with the timer. If possible I want to avoid using an external inverting circuit for one of the outputs unless that is only option.

If this is possible at all in the ATTiny, that will be even better. The ATTiny also has 2 pins associated with one timer, but I am not sure it has the same options as the ATMega.

I already have a 20 MHz crystal and capacitors connected on the PCB and 20 MHz clock is working reliably on the ATMega328. On ATTiny85 PCB I have a 8 MHz crystal and that is also working reliably.

Please help. Thank you.

UPDATE: There are some invalid assumptions in the answers and comments so far so maybe I should clarify: Note that in my original post I have stated that I am using a 20 MHz clock, not 8 MHz, and also that I do not need PWM.

The only mode that gives a high enough output frequency seems to be CTC mode because PWM modes are not working for 2 MHz output. Is there a way to invert either Timer 1 output A, or output B, in CTC mode?

I have now switched to a standard Arduino Uno (ATMega328, 16 MHz) instead of my own 20 MHz board to check my code, and this is my code for a nice steady 2 MHz clock in CTC mode from pins 9 and 10, the Timer 1 output pins:

#define tick 9
#define tock 10

void setup() {
  pinMode(tick, OUTPUT);
  pinMode(tock, OUTPUT);

  TCCR1A = _BV(COM1A0) | _BV(COM1B0) ;   // activate both output pins
  TCCR1B = _BV(WGM12)| 1;                // set CTC mode, prescaler mode 1

  // various frustrating attempts to invert OC1B failed. What do I put here?

  OCR1A = 3;                             // set the counter max for 2 MHz

}

void loop() {
}

The oscilloscope traces for both pins are identical and in sync, how can I get either of the two signals inverted? The invert mode in the datasheet appears to do nothing in CTC mode. Am I reading the datasheet wrong, or will I be forced to use a lower frequency and PWM mode after all?

To add a specific "bounty" question to my original query:
So what changes do I need to make to my code above, to make it give perfectly inverted signals at pin 9 and 11 at the highest possible frequency for a 16 MHz clock, whether that is 2 MHz or not?

I will stick with a standard Arduino Uno for now, so that there is no error mode being introduced by my homespun board, and so that anyone with an arduino can try my code above and confirm that it works as I have mentioned and not as I need!


texts:
I have had this LCD lying on my shelf for the past few years and have not been able to figure out how to use it. It is an LCD from the printer Epson TX710W. I searched for a datasheet, but I couldn't find one. The back of the board contains nothing but traces, the whole module has no ICs on it, I think that's all built into the LCD itself. I don't have the original board that the LCD module connects to.

Could someone tell me how to control this with an Arduino? If that is not possible, could you at least point me in the right direction? What communication protocol does it use?


texts: Is placing a diode in conduction path to ground OK?

texts:
Are there any drawbacks to placing a diode in the conduction path to ground for reverse polarity protection?  A major plus is cost, because you can use multiple low current diodes, instead of one larger diode (or PMOS) on the input.

My thoughts are that having an offset voltage which varies with current is not ideal.  I also remember reading that keeping an extremely low impedance path to ground helps to ground high-frequency noise which would reduce EMI. Are there any other issues that I may have overlooked, or does anyone utilize this method successfully?


texts: Why have a 0.1 uF capacitor in parallel with 2500 uF in a power supply filter?

texts:
I'm troubleshooting an old solid-state bass amplifier (Ampeg B-15). The power supply has a 56 VAC transformer tap into a 4-diode full bridge rectifier circuit.

One side of the bridge goes to ground. The output side (power rail) of the bridge has 3 filter capacitors before any other circuitry: two 2500 uF electrolytic capacitors in parallel to ground and a 0.1 uF non-electrolytic in parallel going to ground.

I know the large caps are filtering caps to reduce ripple. What is the function of the 0.1 uF since it theoretically doesn't add any significant capacitance?


texts: How to make a full Wheatstone bridge with 4 tee-rosette strain gauges?

texts:
I am in the process of making a full Wheatstone bridge. I was told to use 4 tee-rosette strain gauges (with axial and radial components in one gauge) to temperature correct the signals. I am interested in measuring amplitudes and phases of stress signals. I understand how to do this for 2 tee-rosette gauges but I am uncertain how to do it for 4 tee-rosette gauges. I guess you need to put them in a series but I am not sure how to wire it. I was also told that it should only take 4 wires out: voltage (V+ and V-) and measuring (m+ and m-).

How do I configure this? I tried something like this but I realized that it will not work because in a full-bridge two resistivities needs to increase and the other two decrease. This alas is not the case for the bridge I drew. Strain gauges are bonded equidistantly around a quasi-square.

@DKNguyen requested further information. The aluminum piece that I am supposed to bond the gauges too looks like this

in which the upper quasi-square is the top view and the bottom rectangle is the side view of the aluminum piece, while the red lines indicate the strain gauge position. It is basically a cylinder with trimmed sides to have flat surfaces to bond the strain gauges to. It is used to measure amplitude and phase of an axially applied sinusoidal wave. A1 and R1 denote axial and radial components of strain gauge number 1. The same notation applies for the remaining strain gauges (2, 3, and 4).


texts: Capacitive dropper power supply for LED - zener/decoupling capacitor?

texts:
Let's say you have a standard capacitive dropper power supply like the following (from Wikipedia):

I understand that these work well for driving LEDs since they act like a constant current source. I was wondering if the design could be (safely) simplified further by removing the zener and decoupling capacitor - the LEDs don't care what voltage they "see" as they're current-limited anyway, and human eyes cannot detect 120Hz flicker.
I mentioned this to a friend of mine and he pointed out that the mains is subject to voltage transients from things like lightning and inductive loads switching off, and that C2 would shunt the majority of these transients away, protecting the LEDs - that seems to make sense, I suppose C2 + the input impedance of the circuit would behave like an RC filter during a transient?
If that's the case, what purpose does the zener serve if voltage regulation isn't important, and why do so many commercial designs seem to include one? Simulating a similar circuit with a 50us/1kV spike (a la IEC 61000-4-5), the LEDs only see a small increase in voltage and current - C2 does limit the transient significantly...but if C2 were gone, is a sub-millisecond overcurrent even that bad anyway?


texts: Relationship between two differently sampled Fourier coefficients

texts: Assume a periodic signal \$s(t)\$ with fundamental period \$T_0\$. If one were to use the period \$kT_0\$ to find the Fourier series coefficients, how would they be related to the standard Fourier coefficients obtained using \$T_0\$?


texts: How to Implement Relational Operation using TCAM?

texts: Can we implement relational operations (<, > , >=, <= ) using TCAM? Even if they are possible to implement, are TCAMs used for relational operations in real life? What are the pros and cons?


texts:
I'm also looking for some component that will have two inputs: the signal (call it pin A) and a reference (pin B). The reference will either be 0V or 1V/5V, so basically on/off. If B is on, then the component will let the signal pass through. If B is off, then the component will block with signal and output 0V. Does such device exist, or can it be made using some more common components like op-amp?

thanks


texts:
If I have an LED such as this

It has a forward current of 20mA
It has a forward voltage of 2V.

If my supply is 3.3v, am I correct in saying I would need a resistor value of 65 Ohms.

My calculation is :

R=V/I
R=1.3/0.02
R=65


texts:
I'm following the tutorial series on YouTube at https://www.youtube.com/playlist?list=PLEBQazB0HUyR24ckSZ5u05TZHV9khgA1O, specifically the "An Intro to KiCad" videos. I'm using KiCad 5.1.2 on macOS, while he uses an older version on Windows, so some of the user interface elements have moved. However, I've been able to figure out what I need to, until now.

I'm on part 6 ("Place Parts and Define Outline"), and he's setting up design rules as published by a board fab (OSH Park in this case: https://docs.oshpark.com/design-tools/kicad/kicad-design-rules/). I was able to find the setting for solder mask clearance in File > Board Setup..., but I don't see anything about minimum track width or via settings, and the Global Design Rules appear to be gone altogether.

Since I'm just following along in the tutorial and don't intend to actually send boards out for production, I'm not worried about having design rules in place... yet. It seems like I might be interested in defining these rules if and when I actually do get around to making real boards.


texts:
I'm trying to create a circuit that detects water, however, I'm looking for a very accurate circuit that can even detect distilled water.

My current circuit uses an Arduino that has a pin constantly set to HIGH, it triggers an event when water touches two wires that shorts the circuit to ground, creating a LOW signal. Unfortunately, this only works for non-distilled water. I tested this circuit with water from my kitchen tap and it failed, which is surprising because my city uses well water and I didn't think it could be pure enough to not conduct electricity.

Is there a technique or design I can use to detect water, regardless of its purity?


texts:
I have embedded application which uses interrupts and dma. The main loop only sends data to PC.

How to design flow diagram of program? How to show interrupts and dma working on flow diagram?

I've found several topics in google about embedded uml diagrams, and some questions there: Designing embedded software , but haven't found examples of such a diagrams.


texts: Does a 20W bulb "overdrive" this transformer?

texts:
My daughter's IKEA reading light has/had a 12V 20W bulb with a transformer that listed that it output "11.5V ~ 10-20W 60Hz".

The transformer stopped working, and I can't find a replacement available online. In my electronics pile I found a transformer that outputs "15V ~ 1000mA" (no mention of frequency, and I've no oscilloscope here to measure it).

I spliced and soldered the light fixture to the new transformer, and it works. The transformer does not get hot with prolonged use, but I'm wondering:

Since 20W / 15V = 1.33 amps, is a Halogen bulb like a low-ohm speaker, where it's going to have such a low resistance that it's going to pull 1.3A through the transformer and it's skinny wires, possibly causing a fire hazard to it? Or do things not work like that with AC, and if anything the bulb is being over-volted but under-powered, and I should feel good about my hack?


texts: Benefits of higher order low pass in a negative feedback loop

texts:
Let \$G(s) = \frac{Y(s)}{R(s)}\$ be the loop gain of a negative feedback loop system.

  For example a system like this, where Y(s) and R(s) are the laplace
  transformed functions y(t) and r(t):

At the loop bandwith \$\omega_0\$ \$|G(i\omega_0)|\$ becomes unity. Why is it now benefical to have a roll-off (for \$\omega>\omega_0\$) as steep as possible? For example in a PLL you often find several low pass filters in the loop filter:


texts:
I am using components like these:

How should I be connecting this to the breadboard. I am now inserting wires and pulling them to the sides but whenever I touch the breadboard, contacts disconnect and that is making the debugging process so much harder.

I am thinking of soldering little wires, but can I solder something this small (should be like 2.5 mms between inputs) for the first time and be successful?


texts: Selector Switch switch, output should be left open or grounded?

texts:
I am currently designing a circuit and I'm using a Selector Switch. The goal is to control if we are bypassing an other component of the circuit (the 24 VDC will be sent to a PLC that will treat the Bypass). Here is my current design:

I will not be using the leftmost output, so my question is if I should ground it or leave it open.

Also, this is my first time designing a circuit with a switch.

Thanks a lot,
luisarcher.

EDIT 1

New design:


texts: I got this old wattmeter with only 2 terminals in the back. It says 60 mV, which I haven't seen in similar ones. How is it supposed to be connected to measure kW?


texts:
I am reverse-engineering a board which has a Xilinx Spartan 3E FPGA, with VCCAUX powered by a 2.5 volt regulator. Below is the PCB layout for the regulator part of the circuit, and something seems very fishy to me.

My apologies for the horrible pixelation, this was the highest resolution I could get with the equipment I had available. Anyway, the SOT23-5 component labeled "LFSB" is a Texas Instruments LP3988IMF-2.5 linear voltage regulator. I have traced out the schematic below from the board layout:

You may already have noticed the source of my confusion: I have no idea why they would have placed a 316 ohm resistor directly across the output of a 2.5 volt regulator. All that does is waste 7.9 milliamps. I cannot seem to find any reason for doing this. I wonder if it is a design flaw, and that resistor is actually supposed to be connected to the PG pin instead of to ground. I have triple-checked the original PCB, though, and it definitely connects to ground and the PG pin is not connected to anything. If this is an error, however, it would explain why they used a separate trace on the low side of the resistor instead of connecting it to the copper ground pour that's right there. I also wondered if the regulator may require a minimum load in order to maintain a stable output, but that is not the case for this regulator. There are no minimum load requirements. I also considered the possibility that it was intended to bring up VCCAUX more slowly for sequencing purposes for the FPGA, but reading the datasheet this also does not seem to fit - there are no strict sequencing rules for powering up the Spartan 3E.

Can anyone think of a reason why someone would intentionally place a 316 ohm resistor directly across the output of a 2.5V regulator? I considered it might be a bleeder resistor for the output capacitor, but it seems like too low of a value for that.

EDIT:
Perhaps this additional information will help. The datasheet for the Spartan 3E specifies what the VCCAUX supply is used for:

  VCCAUX: Auxiliary supply voltage. Supplies Digital Clock Managers (DCMs), differential drivers, dedicated configuration pins, JTAG interface. Input to Power-On Reset (POR) circuit.


texts: Reduce EMI generated by old AC motor from an electric knife

texts:
I have an old electric knife (220V 50Hz) which seems to produce a lot of EMI.
Some clues on that were a "bzzzz" noise from PC speaker I noticed sometimes when someone use it.

Recently I bought a device which has touch-buttons and I noticed when the knife is in use the device detect false touch. So at this point I think that knife produce a lot of EMI (maybe due to it is an old model?)

So, I would ask: is there any way to reduce them (capacitor on AC motor,..)?

Or can I make a sort of shield?
(eg. whith alluminium sheets glued inside the plastic cover).

Please don't suggest to replace it :) the question is just to know something more about EMI, shielding, etc..


texts: Signal to noise degradation based on noise temperature vs noise figure

texts:
I have a question regarding the signal to noise degradation after a device with a known noise figure.
I must be wrong in some of the assumptions I'm making. As far as I know, the S/N degradation should be equal to the noise figure, but if I calculate it using noise temperatures, I get very different values.
Let:
SNidB: Signal no noise at the input, in dB
SNidB: Signal to noise at the output, in dB
Te: Excess temperature of the device at the input
T0: Reference temperature = 290 ºK
Ti: Noise temperature at the input = 10 ºK (e.g. an antenna pointing at the sky)
Nf: Noise figure of the device = 0.8 dB
Ps: Power of the input signal = -120 dBm
Pni: Noise power at the input
Pno: Noise power at the output
B: Bandwidth = 2.4 kHz

The noise power at the input is:

Pni = 10log10 (kTi*B / 10^-3) = -154.8 dBm

So, the signal to noise at the input:

SNidB = -120 + 154.8 = 34.8 dBm

If we calculate the noise power after the device in terms of it's noise temperature contribution:
Knowing that:

F=1+Te/T0

Nf = 10*log(1+Te/T0)

Then, with our given Nf of 0.8 dB:

Te = 58.7K

And the noise power at the output is

Pno = 10log10(k(Ti+Te)*B / 10^-3) = -146.4 dBm

So, the signal to noise at the output:

SNodB = -120 + 146.4 = 26.4 dB

Which gives us a degradation of 34.8 - 26.4 = 8.4 dB
But, according to the noise figure definition
** Nf = SNidB - SNodB, which should be our given 0.8 dB != 8.4 dB
¿What am I doing wrong?
Thanks in advance.


texts:
thanks for giving a look on my question.

I bought a spark plug, a 12v 5A power supply and a ignition coil (gy6, from a Chinese store).

I've searched some schematics and tried to understand how will I make this spark plug make a spark.
Well, I've tried somethings and some went wrong (short circuit).

The ignition coil has a neutral connection and a CDI (Capacitive Discharge Ignition) one. I though the CDI connection (which is green) received a positive connection. And if I turn it on and off the spark plug would spark. Well, nothing happened...

Can anyone give me help in a way that I could make the spark plug spark?


texts: Why do some microcontrollers have numerous oscillators (and what are their functions)?

texts:
Currently I am reading through the Arm based ATSAM4L series datasheet, and in the sections BSCIF and SCIF I have encountered at least 8 different oscillators/clocks (see image below). I understand that an oscillator is necessary for a clock signal for the MCU, but why are so many different sources necessary for this MCU family and MCU's in general?
EDIT: And what are the functions of these specific oscillators?


texts: Charging capacitors with computer power supply?

texts: I am an AP Physics student in high school, and I am in a group that is doing a project that will involve a bank of capacitors taken out of used disposable cameras hooked up in parallel.  We need to charge the capacitors.  My friend had an idea of charging them with a power supply taken out of a computer.  I am wondering: is this safe and will it work?  The power supply is rated at 115 and 230 volts; the capacitors are averaging 100 micro farads and 330-440 volts.


texts:
I have two macros:

 #define POKE(addr, val) (*(volatile unsigned int *)(addr) = (val))
 #define PEEK(addr) (*(volatile unsigned int *)(addr))

What they do if I call them like this:

ulKey = PEEK(NETX_IO_CFG_ACCESS_KEY);
POKE(NETX_IO_CFG_ACCESS_KEY, ulKey);

If   #define NETX_IO_CFG_ACCESS_KEY     0x00100070U


texts: Incorrect frequency from crystal oscillator

texts:
I acquired an old Eistar SJ-1 Digital pulser, however the frequency it
generates is always 66% of what its supposed to produce. Turns out that
the frequency coming out of the frequency stage (at Pin 11) is 66% of the
16MHz crystal or about 10.6MHz. (The 74LS38 is an open collector quad
NAND gate)

I opened it up and traced out the layout. The frequency stage looks
like to that I have now learned as a Pierce type NAND gate oscillator. I
have drawn an abbreviated schematic of the digital pulser showing the
frequency generation stage.

In the Pierce type oscillators I have researched, there is a capacitor in
between the nand gates where resistor R1 is; however in this design
there is a 2.2k resistor (R1).

What could be causing the wrong frequency to be generated? How I proceed
to troubleshoot and correct the pulser? Should I:

Replace the crystal with another and check?
Replace resister R1 with a capacitor as I have seen in a Pierce type
oscillator. I am guessing since the design would have worked at one point in time, R1 is not an issue here.

Any guidance would be appreciated.


texts: Analog and Digital GND on top of each other

texts:
I am designing 4-layer mixed signal PCB and it is totally crowded (with components).

I know how analog and digital grounds should be separated below components. But I do not have enough room in some places to do this properly.

So I came up with the idea to have AGND on a second layer below analog parts (on the top layer) and have digital tracks at the bottom layer and below that a DGND.

What would be the main cons of that kind of solution?

This is going to be only in some places where I am lacking the board space. But something like this.


texts: Can I use TI's cc2541 BLE as micro controller to perform operations/ processing instead of ATmega328P AU to save cost?

texts: I am using arduino pro mini (which contains Atmega328p AU) along with cc2541(HM-10) to process and transfer data over BLE to smartphone. I am wondering if I can use cc2541 itself for processing data in order to remove arduino from circuit, so that I can save power and money. I am quite new to electronics domain. Please suggest any ways to achieve it.


texts: Do I *need* a TVS Diode at the USB connector?

texts:
I've got a typical electronic trinket that will be connected to laptops and wall warts to recharge.  Fairly cost-sensitive.

Will a spark completely destroy the MCU with a USB peripheral?  Is there a rule-of-thumb for how often this happens?  One in a million devices?  How standard is it to include these?

I'm considering something like this and I am welcome to more suggestions for typical USB peripheral devices.


texts: How to make multi type voltage input? 24AC/DC to 24DC?

texts:
Task: Input voltage: 24V AC or DC (Client disides what to input into divice) output voltage 24V dc output current 1.25A.
Buck-boost converter is a simple and expensive solution. I need some how to dicide to regulate voltage when AC is an input and pass thrue when input is DC. Please help, sorry for English!


texts: I'd like to know whether my attempt to increase duty cycle will work

texts: I've been looking for a solution to make an astable multivibrator give me a 90% duty cycle or a duty cycle above 50%. This is what I came up with. I have very limited resources and means of testing, so I'd like to ask for your opinions or what I should do to achieve my goal.


texts:
Can someone help me with this push button?

I want to connect to an Arduino, it works fine with a small one but with this big one it conducts when press and releasing.

The problem is that the push button conducts when pushed and released so 1 push = 2 times conducting. So the Arduino is receiving two signals and turns on and off. I used a debounceing hardware circuit.


texts: Why isn't there an electrical potential?

texts:
I have two different DC power supplies (6 and 12 volts, let's call them A and B). They connect to the wall and provide a negative and a positive terminal each.

I tried to measure the voltage between the positive terminal of A and the negative terminal of B and measured 0V.

I don't understand why the potential difference between the + and - terminals of different power supplies is 0V. One could say that they don't complete a circuit, but they should, they both come from the mains of my house.

Can someone please explain me what I am thinking wrongly?

Thanks in advance,
Calvin


texts: Eagle - How to make the router ignore internally connected pins (in a package)

texts:
I have made a tactile switch package and as the picture shows pin 1 and 2 are internally connected, same for pin 3 and 4.

The package have 4 pads and the symbol only 2. I have connected pads 1+2 with symbol pin 1 and pads 2+4 with symbol pin 2.

Now, here comes the problem:
The router insists on connecting pin 1 and 2 to each other, same for pin 3 and 4. (as shown here)

Since these already are connected inside the package it isn't necessary to connect them on the board. In fact the router should be able to use this fact to optimize the result (as in this mock up where the yellow trace can run straight under the package).

How can I get the router to understand that these pins already are connected internally? In fact it can benefit from it and use them as a bridge to span over whatever traces running under the package.


texts: Altium - Invisible unrouted nets/components?

texts:
I've got a design in Altium and while routing, I moved a few resistors. They somehow accidentally got deleted and wouldn't undelete. I brought them back with an ECO, and placed them where I want them. Now, I have connection stringers going to their old location, and can't seem to get rid of them. Anyone else come across this?

Edit: Design rule check does not fix this.


texts: Calculating the mean path length of a core

texts:
I have the following magnetic circuit problem:

For the left hand core, the mean path length calculated in the solution manual is 1.11m.  However what I don't understand is, why is the length of the air gap included? Don't you have to subtract the air gap length from the total length of the core?


texts:
I am working on an Active Clamp Forward converter.
Schematic is given here:

Specs:

Output voltage-5V
Input voltage 26..42V
frequency=500KHz
Output power=10W

It is working fine in open loop, but in closed loop I am getting a ripple in output Voltage of 2.5 Volts Peak to peak.

Voltage waveform is given below: waveform

I have designed controller considering settling time and load disturbance rejection. Here is the bode plot of my plant Gvd(s) and my plant+Controller.
What should I do to reduce the ripple in output voltage.

Note1: to implement the controller TL431 and opto-coupler 4N25 are used.

Note2: No ripple is seen in the simulation.


texts: At what point one has to use an I2C buffer?

texts:
I am designing a system that can be expressed on an abstract schematic like this:

There is a main MCU that acts as I2C master and some slaves. Some of them are on the same PCB, but some are connected with cables on other PCB's.
In case of Slave7 and Slave8, there is a "serial" connection: A long cable goes to the PCB4 from PCB1 and then from PCB4 to PCB5.

I am working in standard mode (100 kHz). Speed is not the case in here but reliability. This circuit seems to me to have a lot of capacitance because of many connected devices and long cables (from 1m to 2m).
I am thinking of using I2C buffers, such as PCA9515A.

I consider few options:

Do not use buffers at all, maybe at this speed it is good enough with low resistance pull-ups?

Use only 1 buffer to divide the bus on 2 sides: On the 1st side: Master, Slave1, Slave2, Slave3 and Slave4. on the other: Slave5, 6, 7, 8.

Use many buffers (each PCB would have one). PCB4 would have 2, as it is "bridging" the bus to PCB5.

What do you think would be necessary? I understand that this is a function of bus capacitance and cables lengths, but I am looking for a scalable generic approach here.
I would appreciate all help.

Sides notes: All devices are 3V3 logic, so no gain on making the signals amplitude higher. I was also wondering on converting the SDA bus signals to differential pair with dedicate IC's, but that seems to much, the cables are not that long.


texts: Can an amplifier slew rate be used as a low pass anti-aliasing filter?

texts:
A slew rate calculator says that for an arbitrary 100MHz signal a minimum slew rate of 1884V/μS is required.

If I used an amplifier with that exact slew rate is it also a low pass filter?  It seems like if it physically can't respond faster than the Nyquist frequency it could have a superior drop off capability than a typical anti-aliasing filter.


texts:
I finally broke down and bought this board:
http://hackaday.com/2010/02/28/open-source-logic-analyzer-2/

It "seems" like it would be really helpful, the problem I'm having is getting it setup, I am not finding much of a "how to" anywhere. Here are the problems I'm having.

I would like to get it working on both my windows and linux machines, the problem with the windows machine is that using the logic analyzer software I can't see the "capture" button at the bottom of the screen cause of my netbook resolution, and since I can't change my resolution I can't get it working there.

My Ubuntu machine I couldn't find a download for the S/W except in a .exe format, so I had to download and install wine on my machine, but when I plug in my board I'm not sure if it's detected. There appears to be a rxtx module I need to setup and install. But I'm not sure what version I should use. I found links to some of this from the comments (where I in fact commented) here: Dangerous Prototypes

does anyone have any good suggestions on what to do at this point?

Also anyone have/know of a clear step by step guide (with possibly copy paste commands for the command line portion? as the wget calls can get hard to read and I'm not sure what the link is most times)


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What kind of power supply topology(s) should you use for a CC and CV programmable power supply with the following parameters?

input: 230Vac
output: 0 - 1000Vdc / 3A max.


texts: Alternative method for tying bunch of wires

texts: I'm making control panels on which some heavy duty PCBs are mounted, with many wires (approx 1 meter long) coming out of it. Wires are  currently tied together using zip ties at every regular distance. It is time consuming, so does anyone have any alternative? Note that I don't want to increase the cost, so I prefer a cheaper alternative if possible.