texts: Measurement of Quiescent Current and Operating Current in Gate driver

texts:
In datasheet they have provided two parameters named Quiescent Current and Operating current in which I am measuring quiescent current i.e, ground current flowing from the device VDD to GND , when device inputs (HI,LI) are grounded (test conditions as mentioned in datasheet.

I am measuring Quiescent current at 1 (VSS) for now from below figure, Or should I consider current at 2 (RT1 and RT2) so that it comes to Quiescent current= Current at 1 + Current at 2 ?

(RT bias voltage is 3V which is given internally)

Where should i measure operating current providing f=500KHz input?

This table gives operating current for 25 degree as 1.5mA

When I relate this to below plot which is w.r.t to temperature the operating current contradicts the table value.

Can anyone shed some light on these parameters measurements


texts: Slowing Down Capacitor Circuit discharge rate

texts:
I am currently trying to use a 5 Pin relay on a Motorcycle indicator circuit. The concept is I have a Daytime Running Light (DRL) that is in the same housing as the indicator. When the indicator is on, I would like the DRL to go off.

So far, I have wired a 5 Pin Relay with a Capacitor as the current from the indicator is not constant (As the indicators have to flash). Initially I tried building this circuit without a Resistor. However, either my capacitors are not big enough (Tried 1000uf & 4700uf) or they are discharging too quickly without the resistor.

Relay is 20/10amp 12v with a current draw of 0.15amp.

How do I work out what size resistor I need?

The current circuit is like this

Indicator Wire --> 1w Diode --> 16v Capacitor (1000uf or 4700uf) --> 5 Pin Relay

I need the capacitor to output enough current to keep the relay open (NC Relay) for approximately 1/2 second (between the flashes of the indicator).


texts: Why is electricity consumption billed in watts and not amperes?

texts: Basically the subject. Why would companies bill for wattage instead of amperes?


texts:
I have a battery pack for 3S1P li-ion batteries, with a charger. The battery protection board inside the battery pack does not have cell voltage or temperature monitoring.

Can I replace the batteries and their configuration to a 3S2P configuration, and keep the charger? I plan on replacing all the cells with 6 identical, but higher capacity cells.


texts: Are USB Type A data lines unidirectional or bidirectional?

texts:
I want to isolate the data between my computer USB and my FT232RL (as usb to UART converter) to communicate with my arduino Like this:

simulate this circuit – Schematic created using CircuitLab
What i want to know is, if usb type A (or usb 3) are bidirectonal in order to select the appropriate Digital Isolator. (Some dc isolators are unidirectional and they are cheaper than the bidirectional ones)
I was whinking USB are unidirectional, but then i saw in wikipedia here:

It says That both lines are driven LOW by the host. So, it is bidirectional?


texts:
The various range switches on my oscilloscope obviously collected some dirt over the years. Sometimes the input attenuators show a frequency dependent response (just like poorly matched probe) and the timebase wiggles all over place. It is a fully analog scope and I have full service manuals.

I've seen spray cans used for cleaning these switches, are they any good for this kind of job (measurement equipment)? Are there particular types I should avoid? Are there particular techniques / best practices to clean these switches?


texts: Battery charging and amperage for Li-Ion

texts:
Simple question:
Is low amperage good for battery? Is it decrease wear level?
Ex: we have battery with 2A recommended. Will it be better to charge it with 1A?


texts: Do thermal cutoffs exist that would work with a line that is 40-75V 0.5A and a max temp of ~85°C?

texts:
I have a bunch of COB LEDs that I am going to wire in series using an LED driver. The driver gives off between 40-75V and 0.5A max. The circuit should run around 70V and 0.5A.

Due to space requirements, I need to locate the driver away from the light casing. Thus, the 70V 0.5A line is the only thing that will be running into the case to the LEDs. I would like to put a thermal cutoff (triggered at around ~85°C) in the case, but it seems most cutoffs are either AC or DC (but rated for much lower voltage).

I've searched Digikey and Mouser but can't find any cutoff that would work. I'm guessing there must be some solution but I don't know enough about various electronics.


texts: Looking for this spade connector and KiCAD model

texts:
I am looking for this part but with single male to female connector, KiCAD PCB module and 3D model. I am struggling to find the part name, at the least.

I appreciate every bit of help!


texts: Best Transistor Equivalents for A509 and C509 Transistors

texts:
I found a one pulse activated automatic trigger circuit and it has A509 and C509 Transistors to be used.
But, these transistors are extremely rare and very hard to find.
eBay has those both, but it is not worth to buy according to huge import charges and shipping fees.

Circuit Diagram:

Please can you recommend best equivalent transistors for A509 PNP and C509 NPN Transistors?


texts: gray color on logic function with NMOS in Proteus

texts:
I'm trying to design this function:

(A.B) + (C.D)

every things work fine but there is one weird issue that both branch (A.B) and (C.D) must be 1 or 0 at same time otherwise gray color appears and output comes unknown (as shown in screenshot below) what should i do to fix this?


texts: BMA180 accelerometer. How does it manage to share pins between I2C and SPI?

texts:
BMA180 accelerometer can be either SPI slave or I2C slave.  The pins for both buses are shared.

SPI mode                    I2C mode
---------------------------------------------------
SDI  input                  SDA  bidirectional (!)
SDO  output                 ADDR address bit, input
SCLK input                  SCL  input
CSB  chip select, input     I2C  mode select, input

According to the datasheet (see chapter 8), the selection between buses is done through the CSB pin.  When CSB is low, the device is an SPI slave.  When CSB is high, the device is an I2C slave.

Here's a failure mode, which I'm concerned about.  Suppose, BMA180 is on the SPI bus.  There is also another device on the same bus with it’s own chip select.  Suppose, SPI bus master is communicating to that other device.  CSB for BMA180 is high, so it’s I2C should be enables.  BMA180 sees clock edges on SCL (SPI's SCLK) and bits on SDA (SPI's MOSI) flying by.  What if some of these bits look to BMA180 like a start of a valid I2C read transaction, and BMA180 starts to output data and clobbers the existing SPI transaction?  How would the design of BMA180 prevent that?

This is a matter of curiosity.  I haven’t experimented with these issues yet.  I will be using BMA180 on SPI.

Any suggestion, insight or reference is really appreciated!

Update.  Found something in the datasheet (see 7.7.11).  It recommends disabling I2C by setting the dis_i2c bit, if communicating with BMA180 via SPI.

  When SPI interface is used, it's highly recommended to set dis_i2c to
  1 to avoid malfunction.

BMA180 has built-in EEPROM.  Register contents can be stored in the EEPROM and automatically loaded on power-up sequence.  So, it's possible to make BMA180 ignore I2C completely and always.

Update.  L3GD20 gyro is another IC, which shares pins between I2C and SPI in a a similar way.  It doesn't seem to have a bit setting for disabling the I2C mode.  So, it would require an OR gate like ADXL345, which @markrages brought up.

Heads up!  Bosch stopped shipping BMA180 (official letter here).


texts: Usage of 3d printer hotend outside of printer

texts:
I am trying to repurpose an old hotend of my 3D printer (Link) as an improvised temporary "space heater" to raise the temperature in a small enclousure by 5-10°. I happen to have a 24V 48W power supply lying around, so that is a great fit for the 24V 40W heating tube.
For some simple testing I directly connected the two ends of the heating tube to the 24V PSU. While it worked, after a few seconds I noticed the dust on the tube burning up. Since I was testing in a safe environment I let it continue heating up and after 10 or 20 seconds the stainless steel started to glow red, so I disconnected it. While apparently in terms of ratings everything is fine (fuse of the PSU did not blow), obviously having a red hot glowing and smoking steel tube is not what I intend to have.
I remember from setting up my 3d printer that various parameters have to be configured to properly adjust the PWM control for the hotend, so I took an appropriately rated DC motor controller (VNH5019) and set it to 20% duty cycle. While it didnt heat up so fast it still started smoking after roughly 20 seconds.
I am wondering, how are those ceramic heating tubes normally wired? Heating my 3d printer up to 240° takes 2-3 minutes, the steel tube glowing means it went to like 400° in just a few seconds. Is there some current limiting normally involved? Are they running at super low duty cycle? For both of them: Why not use a heating tube that does not require current limiting/small duty cycle for the working temperatures?


texts:
I've been trying to debug a UART communication issue on a custom design based on ADM00667 development board where there are only a few minor changes.
I have the dev kit hooked up to an nRF52840 BLT MCU and the code works flawlessly, I'm able to send and set registers, and have been reliably getting data from the setup for three + weeks now.
I've connected TX/RX 3.3V and GND between the nRF52840 and MCP39F511 Dev Kit. Based on this setup I've spun a PCBA for a product. When I load the code and check COM with a logic get a strange event on the UART bus. The baud rate is set at 9600, so slow, and the logic level is 3.3V.
During normal operation I send a read command and wait a few ms for the data and read it. Working it looks like this.

What I'm gettin on the custom PCB is the correct data being sent but before the TX has completed RX responds with data that makes no sense and has no relevance in the MCP39F511A datasheet.

I've tried a factory reset of the chip based on the datasheet and get no ACK or NAK back. At first I thought it was crosstalk but after looking at the scope capture data found the RX line to be too strong of signal operating between 3.3V, and that the data was repeatable, everytime I try to communicate with the MCP on our custom PCB I get similar data.

The only differences are trace lengths, and the isolation chips. The ADM00667 board uses ACSL-7210-50RE even though the reference schematic uses the FOD8012AR2 that I used on our PCBA.
I've checked for shorts on all the pins on all UX chips, and found nothing. I've cleaned all flux from the board, added wires from all pins to bypass the traces from UART to make sure it wasn't crosstalk and still get the same exact scope capture.
I'm unclear if the MCP39F511A needs to be set up before data can be read, but the datasheet says the chip comes pre calibrated. "Fast Calibration Routines And Simplified Command Protocol" So I've tried changing the calibration parameters and I still get this RX noise/error.
I'm relatively new to debugging UART, and wanted to know if this is a problem someone might have encountered before and if I'm misinterpreting my observation wrong. I'm out of ideas as I have a DEV setup that works and two PCBA we’ve created that have the same exact issues. I'm happy it's repeatable because it makes debugging easier. I'm still trying to set other registrars and or clear system errors so I'll update once I've done that. But I'm not sure what else to try if those two parents also fail.
I'm open to paying for help, so if you have the time and want to make some cash and dive into this issue deeper I'm happy to work out a deal to get resolution and hopefully learn something.


texts:
as a class project, we were given a circuit schematics of a low distortion audio power amplifier. and we were asked to simulate it, i did that no problem. however I am trying to understand the circuit but the professor didn't tell us anything about it except that it is a class AB amplifier.

I know that class AB is a combination of both class A and B amps, but after i looked at the circuit i couldn't find the class A or the class B amps.

can you guys explain to me what the different parts of the circuit do.

thank you and have a nice day.

this is the exact circuit the professor gave us

this is my attempt at drawing it.

this is the output vs input, the input is the green the output is the blue


texts: High impedance op-amp using guard ring to drive a shield

texts:
http://imgur.com/a/GSALb

http://imgur.com/gallery/9QrWO

So I'm looking at the first picture and I'm trying to figure out now the whole shielding part of the circuit works right now. The second image is the op-amp in use (INA116). The paper mentions that it's using the guard inputs to drive the shield, which will minimize signal pickup from other sources than the signal.

I understand that the guard is a wire around a high impedance node that mades sure that other nodes don't interfere with the node. Other than that I'm completely at a loss as to what to do.

I also understand how transistors work, but if anyone could clarify how the resetting actually works on this circuit that would be great. The transistors turn on when the input voltages approach common-mode input range of the amplifier.

Thank you!

edit: I tried to put the two links up as images, but it wouldn't work ;-;


texts:
I am trying to make a small box to take the mono audio output form my analog synth and run it through a panning knob so I can control where in the stereo mix the mono signal is placed. The goal is to be able to easily change the L/R pan of the synth in the output during performance. I am aware of Pan Pot circuits like this one but that seems above my current electronics ability right now.

Would it be possible to instead do something much more simple like getting a dual gang pot like this one, wire the mono signal to both sets of leads so that the one channel increases as the other one decreases? Or would this cause the center position to have less volume than the full right or left position?

In short, is building a full Pan Pot circuit my only option or is there something more simple I can do instead?


texts: How to choose between different equivalent PLL/divider configurations?

texts:
If there are multiple ways to get the required clocks for a given CODEC, how do you choose between them?

For example, if a CODEC can accept 64fs, 128fs, 256fs, and has an internal PLL that can generate any of these, why choose one configuration over another?

Lower frequency clocks reduce EMI?  Lower frequency clocks draw (slightly) less current?  PLLs work better / are more stable / have less jitter when __ is __?

Likewise, if you could choose between two configurations that both work:

DAC MCLK synthesized from SCLK, ADC divided from MCLK
ADC MCLK synthesized from SCLK, DAC divided from MCLK

Why choose one over another?  Use the divided MCLK for ADC because it's more stable, and ADC quality is more important than DAC?

In other words, there are multiple possible configurations that work, but what considerations might go into deciding which is best?


texts:
May I know this is a fixed-biasing circuit or voltage-divider biasing circuit?

Component List
R1 = 10K 1/4W resistor
R2 = light-dependent resistor (approx 2K resistance under light)
R3 = 2M2 1/4W resistor
R4 = 1M 1/4W resistor
R5 = 470 1/4W resistor
C1= 10µF 25V electrolytic capacitor
(10µF gives initial delay of approx 25 seconds; use 22µF to increase to approx 50 seconds)
C2 = 100nF 63V polyester capacitor
D1 = 1N4148 diode (or 1N4001)
Q1 = BC548 NPN transistor or similar
IC1, IC2 = 7555 or TS555CN CMOS timer ICs
BZ1 = piezo buzzer
B1 = 3-6V battery pack
(3V may not be enough for some piezos - I used 4 x AA batteries to provide 6V)


texts: RC differentiator giving a higher output amplitude than input amplitude

texts:
This is the circuit:

simulate this circuit – Schematic created using CircuitLab

And this is the output:

I am unable to understand the increase in output amplitude as compared to the input's amplitude. Mathematically it makes sense - rate of change is quite high. But electronically I am having a hard time wrapping my head around it. How can additional voltage be generated with R and C?


texts: Can smaller trace width limit the current flowing through the PCB?

texts:
I am a computer science student and I am a newbie in electronics.

I have designed a PCB for SIM800L, and I forgot to change the trace width of the copper rails. By default, the routing width was set to 0.254mm. Now once my PCB arrived I have soldered all the components to the PCB, and I have found that my design failed.

I suspected on the trace width of the PCB because since SIM800L module doesn't come with an onboard voltage regulator, an external power supply adjusted to the voltage between 3.4V to 4.4V (Ideal 4.1V) is required. The power supply should also be able to source 2A of surge current, otherwise, the module will keep shutting down.

Unfortunately, this has happened to me as well. So as I have no prior experience in PCB designing I just wanted to confirm whether it is because of the routing width or else there is any other reason for that.


texts: The difference between storage patterns in RAM or SD cards from EEPROM

texts:
I have used EEPROM to store data in embedded systems. I would like to know about the pattern of RAM and SD cards which were used to store data. Is it that complex in terms of using RAM or SD cards? I trust it must be a purpose-oriented choice of using RAM/EEPROM/SD cards.

I have two questions to ask:

How is data storage different in these two from EEPROM as in EEPROM we can access byte wise 'read' and 'write'?
How different is RAM and SD cards apart from the speed of transactions?


texts: OK to connect ring terminals directly to a PCB?

texts:
I am designing a PCB board and was wondering if there is a reason not to use ring terminals directly to a PCB.  The PCB could have a pad surrounding a hole like I often see as ground connections.  A small bolt could go through the PCB with two nuts, one holding it to the board, and another to hold the ring terminal down.

I've tried those little green screw terminal things where you can stick a wire in the side and screw down the top, but they always seemed flimsy for the relatively big wire I am using.  I've also tried terminal blocks where one side has a wire soldered to the PCB and the other side can be connected to with a ring or spade terminal, but that seems like extra work when the PCB could be designed to screw to directly.

Just wanted to check if I was missing anything obvious here as to why not to do this.


texts: Custom 12 V DC motor control with ESP8266 without PWM

texts:
Scenario

(you might want to skip the lengthy back-story)

I'm trying to integrate my home ventilation system with my home automation. It currently consists of ten fans with ceramic heat recovery elements built into the wall and a central control unit. The control unit has four settings to control the airflow (off, 1, 2, 3).

The control unit has two 3-wire connectors, "forward" and "reverse". So five fans pull air in while the other five push air out. This is reversed after a while for heat recovery.

My goal is to control each fan individually with a per-fan control.

The "interface" between control unit and fan works like this:

each fan is connected with three wires: 12 V, GND, Control
12 V is always on
control is a DC voltage between 0-12 V, not PWM
control has a very low current (< 150 µA)
control 0 V is full reverse, 12 V is full forward
there is a neutral zone around 5 V turning the fan off

Prototype

My prototype is actually working quite well. Basically I branch 12 V to an AMS1117 to power an ESP8266 with 3.3 V. PWM signal on GPIO -> RC circuit for smoothing -> LM358 op-amp to amplify the voltage to up to 12 V. This new control signal drives the fan speed.

Problem

I am not satisfied with the RC + LM358 setup. It requires a lot of fine tuning to get a good bias point for both elements. And it depends on the tolerance value of the resistors and capacitors used. (... and it's a lot of soldering I'll have to do for ten individual controls). I don't want to risk damaging the fans by just applying PWM to them since I assume that they contain additional electronics.

Questions

Is there a better solution to get a clean 0 - 12 V DC voltage without RC + opamp?
My preferred solution would be an I2C module with a "0 - 100%" setting that guarantees the selected voltage. Is there such a module?
What kind of built-in motor control am I communicating with?


texts: I am trying to use a buck converter to step down a 48v to 33v. The confusing part is that I am trying to simulate it using LTspice and I can’t figure what how to control the nmos with pulse width modulation . Do I need a control circuit for the purpose of simulation or how can I go about it .


texts: Why does my transistor saturate when I touch the base?

texts:
I have a simple setup with a BC547 C NPN transistor with nothing connected to the base as shown:

I'm using a USB cable plugged into the wall.
Why is it that when I touch the wire connected to the base, the LED brightly lights up?


texts: Calculating current in a parallel AC RL circuit

texts:
I have this for Q4. a):

I have been struggling to calculate this as my numbers do not seem to be correct. When do I include the 90° lead that voltage has over current due to the inductor? Here's my attempt:

I understand that part b is pretty much the same but Xc = 1/wC and I want just the branch, not total current.

Any help or pointers with this would be great as I am a bit stuck on this one.

Thanks


texts: Program SPI flash on board after soldering

texts:
I'm developing a USB DAC using XMOS XHRA-2HPA as USB->I2S interface. XHRA-2HPA is a sort of highly specialized uC which requires a firmware and configuration data to be stored on external SPI flash chip.

I want to install a service connector on the board to be able to reprogram this flash. First I need to be able to power up flash chip without powering up the entire system. It can be done with a sort of manual jumper. But I'm in doubt if unpowered USB interface chip connected to the same SPI bus in parallel can affect proper bus operation.


texts:
I am currently working on a power line communication project.  I want to send an audio signal through the power line. In order to do that I would need to modulate my signal and in this project I am using an LM565 as the modulator and demodulator.

The modulator is pretty much done and now my problem is that I haven't found a proper circuit for the FM detector. I found this one though and I want to ask a few questions

On the LM565 pin 8 is the timing resistor and it is used to determine the carrier frequency in the modulator and the free running frequency in the demodulator. In this picture, the timing resistor in use is a potentiomter so we can scale the free running frequency. Can I just use a fixed resistor if I have count the value of the component I needed to achieve that frequency?
Did anyone in this forum have ever work on a similar project (not really have to be PLC just modulate and demodulate the input signal is fine) and willing to share their schematics?

By the way my carrier  frequency is ~400KHz so the free running frequency should be around that number, too.


texts:
Most automotive vehicles typically have their interior lights fade out 30 seconds or so after the doors are closed.
The way I understand it, closing the door will usually depress a momentary on/off switch, opening the circuit, isolating the lights from the battery.
Even with that main circuit broken, the lights manage to stay lit for a short period of time before dimming and fading out completely.
I always assumed this was attributable to the use of an inline capacitor but have noticed some aftermarket solutions seem slightly more complex than that. (Images below).

What's actually involved or required in these circuits? ie.
What function/purpose do the additional components provide/serve?
Are they necessary?

Caveats:
1. I understand that an increasing amount of newer vehicles are probably providing this functionality via ECU integration. If your answer is about this; it's probably unrelated to the actual question.
2. This question is more concerned with the electronics involved and is not necessarily exclusive to automotive applications, despite the example provided.


texts:
I'm attempting to self-learn as much as I can about electrical fundamentals and circuit building (red flag here I'm sure, but want to be completely honest in the hopes that someone can offer some advice!). I'd like to understand the underlying reason for current and voltage tolerances of a given component.
Current tolerances are somewhat more understandable to me from a physical perspective, but voltage is a little bit less tangible. Would a fair description of voltage tolerance be that it represents the 'strongest' electric field the component can be put in line with before the material starts to break down, or does it have something to do magnetic fields being introduced beyond that certain voltage which could potentially induce current in neighboring components?
Or (perhaps more likely) could it be for any number of reasons deemed necessary by the manufacturer, and I should just accept the data sheet and move on? :)
I'm no EE, but I'd like to understand what's happening a little better on the physical side (rather than hand waving and more water analogies) - any help would be appreciated


texts: Are steady-state values in LTI systems differentially influenced by the rate an input is introduced?

texts:
I have a general question about LTI systems I was hoping someone could clarify.
I'm currently learning about steady state behavior in LTI systems, and how you can evaluate them with different inputs. So here's my question-say we have an LTI system, and let's consider 2 different inputs: a step input with a long duration (say maybe 150 time steps), let's call this A. And another input that gradually increases from 0 to 1 (maybe this gradual increase is logarithmic or linear-I wonder if it matters?), in 135 time steps, and then remains at that value for an additional 15 steps-let's call this B. So that means it takes B 135 steps to reach A's value, but it does maintain that value for a little while at least. Are there general features of LTI systems that could help you predict the behavior of the system in response to the abrupt vs. gradual introduction of an input? Will they reach the same steady state values?

My intuition is that they should both give for the same steady state, but that abruptly introducing an input should reach steady state faster. Although I wonder if the gradual case would allow for a more stable system? Does anyone have any thoughts? I'd appreciate it, this has been bothering me for a while now haha


texts:
I live in India (220-250V, 50Hz). I have a single phase supply coming into my home. The main MCB trips as expected whenever the Live and Earth conductors get shorted. But I observed that my house's MCB trips even when Neutral and Earth are shorted. Is this standard behaviour or Is my wiring or MCB faulty? How can I check? I have a AC voltage capable Multimeter and an AC clamp meter.

Is it something to do with how MCBs work?


texts: Turn ON/OFF a LM2596 based buck converter with microcontroller

texts:
I want to turn ON and OFF a LM2596 based buck converter with a microcontroller GPIO pin. 5th pin of the LM2596 can be used to for that purpose.
Please have a look on the schematic.

My question is whether using resistor is R1 is sufficient here?
LM2596 can take upto 45 V, but allowance on ON/OFF pin is only up to 25 V. So, won't 5th pin see exactly Vin when MOSFET is turned OFF?
In datasheet, regarding the ON/OFF pin it has (on 4th page):
Allows the switching regulator circuit to be shut down using logic signals thus dropping the
total input supply current to approximately 80 μA. Pulling this pin below a threshold
voltage of approximately 1.3 V turns the regulator on, and pulling this pin above 1.3 V (up
to a maximum of 25 V) shuts the regulator down. If this shutdown feature is not required,
the ON/OFF pin can be wired to the ground pin or it can be left open. In either case, the
regulator will be in the ON condition.

Update
(After seeing answers from @Justme and @Andy, telling we can connect MCU pin directory to the ON/OFF pin)
I missed to add this in my original question.
I also want to make sure the converter is turned OFF by default until MCU turn it ON. Default behavior of ON/OFF pin is making the converter ON until it get logical HIGH.
So, if we connect MCU pin directly then the converter will start working soon as it got powered, until the MCU pull it UP. Thus I guess I have to use the MOSFET based controlling as I showed above, right?


texts: I was wondering how I could find the inductor mean current?

texts: If I know the peak to peak value of inductor current, is there a way I could find the average of that current from just knowing the peak to peak ripple?


texts:
I recently joined a 9 volt cell and two 1.5 volt cells to get an output voltage of nearly 6 volt. For 15 minutes or so, the battery worked perfectly. It did not even show any sign of heating and in the next 2 minutes the 2 1.5 volt batteries hiss out and leave a lot of smoke. I am not even sure if its called an explosion. All the batteries were general purpose walmart batteries.

The batteries were connected in the following way:

simulate this circuit – Schematic created using CircuitLab

My guess is that these particular cells were faulty/defective from the very beginning. Can there be any more possible and realistic reason for this kind of explosion?

PS: All the values in the circuit have been measured using a DMM and rounded of to nearest integer or 10th of an integer.


texts: Is there a component that doesn't let anything below a certain voltage through?

texts:
I was wondering if there was a component that would only let current flow if it was above a predetermined voltage.

I am building a subsystem for my project, which is an open door sensor that uses a microcontroller. I am running the circuit at 5 V, and I want an LCD display to display when it is time to change the batteries. The circuit will not have an external power supply to reference the voltage to when testing the batteries.  This is my circuit so far and it only needs this last bit. Whilst the microcontroller can run at as low as 3 V, the LCD needs 4.5 V - 5.5 V to work, so 4.5 V will be my minimum voltage, but I would like to know in advance, so maybe a bit higher.

Any help in understanding this would be greatly appreciated.


texts: Altium Designer - Delete a single Datum in a Datum Dimension

texts: I have an extra Datum in a Datum Dimension that I am using. I want to delete it, but when I try to select it, I end up selecting the entire Datum Dimension. Is there a method to individually select a single Datum so that I can delete it?


texts: What is an ideal current source in real life?

texts:
In page-8 to 9 in Art of Electronics by Horowitz and Hill, the concept of current sources and voltage sources are discussed. Batteries are given as example of ideal voltage source but there seem to be no examples given of an 'ideal' current source, so what is an ideal current source?
My question is different from this question as here I ask about ideal sources, not real sources.


texts:
I have come across several occasions on this website where a circuit is shown with a fuse on the neutral wire rather than the line wire of mains power. For example

from this question.
I can think of good reasons why the fuse should be on the line side. If a fuse on the neutral side blows, and the building does not have ground fault protection devices, then current could still flow from the line to the ground. [Of course, if the fuse were on the line side, and it blows, current could flow between neutral and ground, but the voltages are much smaller] So, it would seem that a line side fuse offers more protection than a neutral side fuse.
On the other hand, I can't see any advantage to fusing the neutral side rather than the line side.
Of course some particular circuit might be fully enclosed in an insulating container. While that, at least somewhat, counters the safety argument for fusing the line side, it doesn't seem to provide any benefits to fusing the neutral side rather than the line side.
So, my question is, am I missing something? Is there any reason to fuse the neutral side rather than the line side? Or are those who designed these circuits just missing an opportunity to make their circuits possibly safer with no compensating benefit?


texts: Reduce minimum operating voltage of an H-bridge

texts:
I have purchased the following H-bridge and I'm controlling it with a microcontroller:

https://www.amazon.com/H-Bridge-Brakes-Forward-Reverse-Full-Duty/dp/B07GFFVZKS

My problem is that the MOSFETs will only conduct when the bridge supply voltage Vhv is in the 10-40V range.
I need finer voltage control for my application and would like Vhv to be able to be as low as 2V  - giving a 2-40V range.
Is there a way I can bias in order to reduce the minimum bridge operating voltage?
 My power supply voltage is 48V. I was thinking to use a separate power supply and bias the gates on the MOSFETS. Any advice appreciated

Thanks

___________________________________________

Here is a question restatement. Use as desired.

I am controlling a Peltier device.
I use a separate power supply to supply a voltage (Vhv) of 2 to 40V smoothed DC to the Peltier device.  (This is derived by PWMing a 48V DC supply and then filtering the PWM to provide smooth DC).

I wish to use a full-bridge / H-bridge to change the polarity of the Peltier device so that I can change it from heating to cooling.
The fully-assembled Full bridge PCBA that I am attempting to use will only operate over a 10V to 40V Vhv range.
I wish to determine why the device is limited to a minimum of 10V on Vhv and whether I can modify it to operate over a 2-40V range, or even 2-48V.
Any suggestions would be welcome.

*Arduino.


texts: MOSFET passes current but has large voltage drop

texts:
I'm a novice in electronics and my friend sent me this circuit diagram:

As requested, I simulated it online and found an interesting result: the MOSFET passes around 130 mA but also drops around 100 V. This means in real life the MOSFET would probably explode by the amount of power going in unless it had a big heat sink. The voltage across R1 is about 12 V. Why is it that a MOSFET could conduct a considerable amount of current but also have a large voltage drop? I thought when they were saturated the transistor behaves like a low-value resistor and a reversed diode when turned off.


texts: Hooking up a load cell to a temperature logger

texts:
I have an idea for little project where I want to log weight changes (standalone) on a bee hive, preferably low-cost.

Now there's a lot of cheap temperature loggers on the market, for example this one: Temperature Data Logger on ebay.

Is it possible to connect a load cell to this or any other generic temperature logger, provided that I apply the right amplification to get the load cell to work in the same output range as the temperature sensor? Or is a temperature sensor output radically different from a load cell output? I have no problem with using a formula to convert the temperature values to kg values.


texts: Differential stage Av value with current sources

texts: Why all books told that Av differential of an differential input stage in power amp is very big? Ad = Rc/re, but if there are current sources in the emitter and collector circuit they will have too big impedance and division one big "Rc" to another big "re" will not give very big "Ad" value. Where is a trick?


texts: Is it possible to build memoryless logic gates?

texts:
I would like to build a memoryless (possibly cyclic) logic circuit.
Perhaps this is not the best name, so let me illustrate what I would like to have with an example.

Consider a state machine with inputs a and b, and outputs i and o.
The values of the outputs are defined by the equation:

i = a * b
o = b

or with the truth tables:

a b | i o

0 0 | 0 0

0 1 | 0 1

1 0 | 0 0

1 1 | 1 1

The output values are completely defined by the inputs, independently of the history of the circuit or of the current value of i and o.

This can be easily implemented by a circuit where i is the output of an AND between a and b, and o is simply b (in this circuit, the values of the outputs are independent of the previous history, so it is  said to be combinatorial).

Now consider the following circuit.

If the initial state of i and o is 0, then the circuit computes exactly the function above. However, if then we change the input, that is no longer the behavior, because the circuit has "memory" (the circuit is not combinatorial, but rather sequential). For example:

i) First we set a and b to 1, so that i and o become 1 too.

ii) Afterwards a remains 1 and we set b to 0, then i and o remain with value 1 (the circuit remembers the previous value).

Then my question is: is there any implementation of logic gates such that in (ii) i and o become 0? More in general, I would like the machine to implement the function above no matter which is the previous history.

I would like to keep the wires between the gates, and simply change the implementation of the gates. My intuition is that if the circuit contains only OR gates, this can be achieved implementing the OR gates with diodes (https://en.wikipedia.org/wiki/Diode_logic#Diode_logic_gates). But I am not sure about this, and I have no clue about how to do that for AND gates (I only care about monotone circuits, so implementing NOT is not an issue).

I will try to give one more example of a simple circuit with one feedback loop and one OR gate. Consider the function o = i and the circuit on the left:

This is a sequential circuit. Assume initally o = i = 0. Then we set i to 1, and o becomes 1. Then, after setting i to 0, o remains 1.

However, if we implement the OR gate with diodes (as in the right image, see https://en.wikipedia.org/wiki/Diode_logic#Diode_logic_gates), then the circuit is not sequential any more. The output o is always equal to i, no matter the previous history. Please, correct me if this is wrong. Then for this simple case, the answer is: yes, you can implement the OR gate with diodes to achieve that behavior.

Thank you!


texts: How do I create a subtractive or dffferential two channel audio mixer?

texts:
I have a desktop mixer made by Behringer (Xenyx X2222USB although I am not using its USB capabilities) which has a line level output that feeds 2 channels of a Behringer USB audio interface (U-Phoria UMC404HD). I have several direct audio sources (including a single headset microphone) that feed the mixer which would be panned accordingly.

What I want to do is to take the left and right line level outputs and create a circuit that divides each output into 2 buffered outputs (in order to isolate any cross-talk between channels) each. One from each channel will go into a summing mixer so I can get a (L+R) signal. The other pair I want to run into a subtractive or differential mixer to obtain a (L-R) signal. The pair will then be fed into channel one and channel two of the interface.

The idea is that I want to create a Mid/Side mix live from a typical Right/Left configuration. I know it can be done from the PA Speaker (Ala Aspen Pitmans Space Station) by deriving the (L+R) and (L-R) signals and feeding them into separate amplifiers with speakers pointing 90 degrees from each other. It can also be done in an acoustic space using a hyper-cardioid polar pattern microphone for the Mid channel and a bi-directional (or figure 8) polar pattern to capture the side channel. This gives a rich stereo sound no matter where one is in the particular area in relationship to the speakers location. I am convinced it can be done in the mixing stage as well. This way I can both record the show via my computers DAW as well as run it through the PA speakers (and/or headphones) via this Mid/Side technique.

I know I can create this in a VST ".dll" file, but I prefer to program in solder. Even if the idea is unfounded, it would make an interesting experiment and may provide the basis of actually figuring it out. In Aspens design, the speakers are at a 90 degree angle from each other on the horizontal axis which allows the phases to not cancel each other out.

How do I create a subtractive or differential two channel audio mixer?


texts: Capacitor voltage in LCR circuit greater than the supply - are my phasor calculations correct?

texts:
When calculating the voltage across the capacitor in the first diagram, It turned out to be greater than the power supply?

$$Z=R+j(X_L-X_C)$$
$$R=250\Omega$$
$$X_L=2\pi\times60\times0.65=245\Omega$$
$$X_C=\frac{1}{2\pi\times60\times1.5\times10^{-6}}=1768.38\Omega$$
$$Z=250-j1523.336\Omega=1543.71\angle-80.68^{\circ}\Omega$$
$$I=\frac{120\angle0^{\circ}}{1543.71\angle-80.68^{\circ}}=0.07773\angle80.68^{\circ}A$$

When I multiply $$I$$ by $$-jX_C$$

$$V_C=I\times -jX_C=0.07773\angle80.68^{\circ}\times 1768.38\angle-90^{\circ}=0.07773\times1768.38\angle80.68^{\circ}-90^{\circ}=137.45\angle-9.32^{\circ}V$$

Is this correct? And if so, why?


texts: Three-level analog output (Ground, 2.5V and 5V) - DAC good enough?

texts: I'm planning to replace the thermostat of my evaporative cooler with a Raspberry Pi plus some control (see Wiring a 24-volt Swamp (Evaporative) Cooler for Control With Relays).  Signaling from the current thermostat to the control panel is done using DC signaling at Ground, 2-3V and 4-5V.  How can I create these three logic levels with the least amount of circuitry required?  Precision is very low (see the +/- 0.5V ranges), but I don't know how much current the cooler control panel will draw on these DC lines so not sure if a simple DAC will be sufficient.


texts: I have an XBEE (XBee 2mW PCB Antenna - Series 2 (ZigBee Mesh)) and it only seems to work within 5 feet of the other Xbee. Is there a certain orientation or line of sight parameter for Xbee's? Is it possible something else could be causing interference?


texts:
Let’s say I have a surge protector that has a 15A cable that is rated 1875 watts at 125V.

If my voltage is low, let’s say 105V the amount of watts it can supply will drop? So its max safe output would be 1575 watts. Is this correct?

Lastly, won’t all the appliances pull more amps as well since the voltage is lower? For instance a charger that is stated to be 12W will simply pull more amps if the voltage is lower to reach 12W. Also if the voltage is higher it will pull less amps to reach 12W? It will not change how many watts it consumes?

I do not need an explanation on voltage and amperage just a simple answer to how it works in this scenario, nothing too complex.

Finally, if a surge protector is rated 15A can you calculate the amount of load just by adding the correct calculated amps based on voltage levels.For instance appliances of 0.2A + 0.3A + 0.5A = 1A load. So I can still use 14A safety with that surge protector?


texts:
I'm in the process of building an 8kW isolated DC/DC converter, full-bridge topology.

I'm seeing some interesting phenomena on the diodes. When each diode becomes reverse-biased, a voltage spike appears across the diode, before settling down to the expected DC bus voltage. These are 1800V fast diodes (320nS spec'd recovery time), and the spikes are hitting 1800V with only 350VDC on the secondary, well below my output voltage target. Increased deadtime doesn't help; the kick still appears when the diode is reverse-biased, and is just as large.

My suspicion is that the output choke is keeping the diodes forward biased during the dead time. Then when the transformer voltage starts to rise in the other half-cycle, the diode gets instantaneously reverse-biased long enough to appear as a short across the transformer winding. Then when the diode recovers, that current is cut off, causing the kick I'm seeing.

I've tried a few things. At one point, I added a flyback diode in parallel to my bridge.

I used the same fast-recovery diodes as are in my bridge. This had no apparent effect on the spikes. I then tried adding a .01 uF cap in parallel to my bridge.

This reduced the spikes to a more manageable level, but the reflected impedance of that cap caused significant problems on the primary. My snubber caps have doubled in temperature!

A few possibilities present themselves:

1) I've diagnosed the problem incorrectly. I'm 95% sure I'm seeing what I think I'm seeing, but I've been wrong before.

2) Use a synchronous rectifier. I shouldn't have reverse recovery issues with that. Unfortunately, I'm not aware of any reverse-blocking JFETs in this power range, and there's no such thing as a reverse-blocking MOSFET. The only reverse-blocking IGBTs I can find in this power range have worse losses than the diodes.

EDIT: I've just realized I've been misunderstanding the nature of a synchronous rectifier. I don't need reverse-blocking FETs; the FETs will conduct drain-source.

3) Use zero-recovery diodes. Again, problems with losses and cost.

4) Snub the kicks. This looks like it would eat way too much power, on the order of 20% of my overall throughput.

5) Add saturable cores in line with the diodes. Two of the largest saturable cores I could find barely dented my kicks.

6) Use a zero-current-switching resonant topology. I have no experience in that area, but it sounds like if the current on the primary changes more smoothly, the voltage on the secondary should also change more smoothly, giving the diodes more time to recover.

Has anyone else dealt with a similar situation? If so, how did you solve it?
Edit: primary-side FET datasheet here.


texts: Altium IPC Footprint wizard Generating Dodgy Components

texts:
I've started using Altium Designer 14 after a break and needed to build some components I started with a EP4CE10 FPGA, but I noticed that despite following the component guidelines as close as possible, I was generating rubbish.

Is it possible some setting somewhere has been changed to cause these errors?

I cannot see any errors between the manufacturers numbers and my own (attached). I also tried generating a soic 8, but again it produces rubbish.

The datasheet: datasheet

The output:

My input:


texts:
I'm experimenting with small motors (just building useless toys so far) and I'm wondering what benefit there would be to using an op-amp to control a motor (top circuit) vs just controlling the motor with a pot directly (bottom circuit).

simulate this circuit – Schematic created using CircuitLab

EDIT:
please ignore the exact component values;  100 ohm and TL081 is just the circuitlab defaults that I didn't change -- I'm just thinking about the general setup of active vs. passive components for the control.


texts: I find it odd that manufacturers specify power rating of Uninterruptible Power Supplies (UPS) in VA instead of Watts since VA doesn't tell you how big of a load the UPS can supply. A case in point is Allen Bradley's 1609-P3000N, where 3000 is the VA rating of the UPS. Had I used power = 3000VA to calculate the load at 120V, I'd have come up with 3000VA/120V = 25A. It was only when I started digging into the spec sheet, I found the Watts rating (2100W). I wonder why the manufacturer doesn't have this rating embedded in the part number since this is the rating you need to determine if the UPS is right for your application (i.e. it can power your load without faulting/nuisance tripping).


texts: Maximum overshoot and settling time for a 2nd order system

texts:
I have a second-order unity feedback control system with forward transfer function $$G(s) = \frac{10}{s(s+2)}$$
Here damping ratio, $$\zeta  = \frac{1}{\sqrt{10}}$$
and natural frequency, $$w_n = \sqrt{10}$$
First, I gave a unit step input to the system. Now I can calculate the maximum overshoot of the unit step response from $$\%M_p = e^{\frac{-\zeta\pi}{\sqrt{1-\zeta^2}}}$$ and settling time from $$t_s = \frac{4}{w_n\zeta}$$
Now, If I give a unit ramp input to the system, Can I use the same formulas above to calculate settling time and maximum overshoot?
For reference, this is my unit ramp response in the time domain
$$y(t) = -\frac{1}{5}+t+\frac{1}{5}e^{-t}Cos(3t)-\frac{4}{15}e^{-t}Sin(3t)$$
As you can see, this is uniformly increasing. How can I find settling time from this? Can I just equate y(t) with unit ramp input and find the time at which they are equal?


texts: Output on Pass-transistor NAND gate lower than expected

texts:
I have an assignment to design an IC NAND gate, consisting og 2 NMOS-transistors and a designed inverter as seen in figure 1 and 2.
But when measuring the output at Vout, we only get about 60% of the expected value, which would be 1.5V.
I can't figure out the issue.
Edit:
I am trying to design my NAND gate according to figure 4.
Our goal is to keep the output at the same level as the input while still holding the true to the truth table

Edit 2
Another suggestion from a group doing the same course, was to make an AND gate and placing an inverter at the output.
Settings:
VDD = 1.5V
Vin_A:

Amplitude = 0 - 1.5 V
Period = 2 ns
Rise Time = 0.1 ns
Fall Time = 0.1 ns
Pulse Width = 1 ns
Delay = 0 ns

Vin_B:

Amplitude = 0 - 1.5 V
Period = 2 ns
Rise Time = 0.1 ns
Fall Time = 0.1 ns
Pulse Width = 1 ns
Delay = 0.5 ns

Figures

[Figure 1]

[Figure 2]

[Figure 3]

[Figure 4]


texts: External transformer for PCB made for someone else a few volts higher than circuit was designed for, will this damage the optoisolators?

texts:
I sold my first PCB to someone for a bowling lane project.
This PCB has 10 opto-isolators(LTV-817) which are connected(after going through a bridge rectifier) to external switches going to a transformer.
When I was designing the board, I had them take a picture of their multimeter which showed 22.4 volts AC. I designed it with this in mind and after considering the voltage drop from the bridge rectifier, I decided on a 1K ohm resistor to be used for each opto-isolator.
I am getting worried now after a unrelated problem with something else and they shared a picture of their multimeter connected to the transformer. This time it shows 25.5 volts AC. The previous reading might have been because something else dropped the voltage down to 22.4 volts.
Would this have damaged the opto-isolators since it is a few volts higher than I designed the circuit for? Should I tell them to get ten 100 ohm resistors to put in line with each wire?
Here is the schematic of one connection, in the actual circuit there are 10 of these with a common side connected together to each bridge rectifier:

Here is the data sheet to the opto-isolator I used
.


texts:
Here is what I am exactly working on:
I have to run an infinite while loop and check the output on oscilloscope. As I change the processor frequency, I will get a change in the period of output square wave time-period, right?
And that is what I have to achieve.
What is wrong with writing the program in below mentioned way in Vivado?
I am working with ZYNQ zc702 evaluation board and Vivado HDL.
Following is the code that I have written:

module validation(
    output a
);

reg a1 = 0;

assign a = a1;

integer counter = 0;

while(1) // Infinite While Loop
begin
    counter <= counter + 1; //The counter goes up.
    if(counter == 0)
    begin
        a1 <= ~a1;           //If the counter reaches 1000, toggle the output.
        counter <= 1000;     // Resetting the counter.
    end
end

endmodule


texts: How do I make sure my electronics design is good from manufacturing perspective?

texts: I am a beginner in electronics design. I have some experience with fairly complex PCB design. I want to design a product that will hopefully sell a lot. How do I ensure that the design is inexpensive from manufacturing perspective? I mean not for a single PCB fabrication but for mass production. I use commonly found microcontrollers like atmel, Texas instrument. Is this the way to go for mass manufacturing?


texts: So I got a bunch of surplus components, there are a lot of soviet semiconductors, resistors, caps etc. Ccan anyone point me in the right direction of testing if the caps are good, for large ones I use my multimeter's ohmmeter and see if they charge, but the smaller values don't even create a flicker. Is there any way to test these?


texts: Chipsets that provides access to baseband bits

texts: Are there any chipsets for high-speed wired connections like USB3.0, Ethernet or PCIe that provides access to the raw signals being transmitted and received along the wire? Kind of like how a software radio provides access to the raw I/Q samples.


texts:
Not a dup of  which barely attends to the technical reasons for or against using 90 degree routes.

As a hobbyist who's enrolling in an EE program in the fall, should I just get in the habit of avoiding right angles in PCB layout? Is this always a best practice or something that only RF or high speed scenarios require ?

Beyond mechanical or aesthetic reasons, are there reason you would want to use 90 degree angles?


texts:
The question is to determine the reference voltage for the comparator shown in the figure below:

After I understood that by the reference voltage is meant the voltage at the negative terminal, then I came up with this solution:

The voltage drop at R1 should be 10 V and the voltage drop through R2 should be 5V. The voltage at the nod ( between R1 and R2) should be 5V. And that voltage goes through the R2 and it also represents the reference voltage that goes through the negative terminal.

I am not sure about this solution. Can someone help me if this approach is correct? Or should I represent that reference voltage using the Vin also?


texts:
I'm working on a 3 phase brushless, sensorless driver (Allegro A4960.)
I need to drive different motors in terms of power.
The voltage is 24V but the current per phase varies from 1A to 6A, so I'm looking for an N-MOSFET suitable for this current.
The A4960 evaluation board uses the IRFR2405PBF but I was wondering if the CSD18533Q5A could be better.
I'm not an expert on MOSFETs and motor drivers.
My evaluation is based on IDrain and Rdson.

Are these 2 variables sufficient or am I missing something else?
Could I not consider the fswitching on the MOSFET to calculate the dissipated power?

In this case I would choose the CSD18533Q5A because of the lower Rdson.


texts: What is the meaning of "combinational assignment" and "registered assignment" to signals? In particular what are the differences between these two types of assignments?


texts: How did people realize they could do logic with electronics? Are there anecdotes or records of the first realizations? I'm wondering about the first "eureka" moments.


texts: Reverse engineering and reimplementing a garden hose water timer

texts:
I bought a cheap chinesse water timer with the idea of reimplementing the electronics to add Lora Radio managment so I can turn or or off the valve from a large distance and all running on batteries.

I want to reuse the mechanical design of the product and create my own Arduino based PCB that fits on the plastic enclosure and I want also reuse the latching solenoid inside the device to manipulate the water flow.

While trying to reverse engineer the product I have seen that it's powered by 3xAAA batteries and uses 3.3v logic (I also want to use 3.3v to be as eficient as possible) , the solenoid needs at least 5v to turn or/off so it uses some kind of booster design to charge a 2200uf capacitor and then dump it's load with a very short pulse in one polarity or reversed polarity using a H-Bridge to open or close the valve.

I came up with the following design while using my tester in continuity mode and following the traces on the original product but I can't really understand how it works (suposing I have done it right!)

The product PCB's

a few questions:

1) Does the schematic any sense at all?

2) For my understanding it's using the inductor to boost the voltage, it's conected to the battery and ground with C11 and R14, since it's only needed to charge the capacitor and it's only required maybe only once a day it's not wasting lots of energy from the batteries?

3) What is R6 and D2 used for? to discharge the capacitor of residual energy? taking a look at the PCB D2 is a pin diode, why ?

UPDATED:

1.-Following @kutukvpavel excelent answer I have redrawn the schematic using the same convention with my original components for clarity.

2.- D2 is a zener diode actually drawn upside down, I corrected it.


texts: 5-10V to 3V3 level converter for bidirectional I/O

texts:
I need connect 3V3 powered MSP430 family processor and PW0268 ultrasonic sonar IC. PW0268 is powered Vcc 5-11V and is connected with MCU via bidirectional IO pin which is internally pulled up (3.5-6.5k) to Vcc as there is an open colector transistor. When Vcc 10V I can measure Vio 7.7V (or 8.7V/6.7V). The function is: MCU generates short pulse, releases IO and sonar IC pull down when response is received. I cannot use my "standard" 74LVC shifter method as they are not tolerant to voltage above 5V. I'm uncertain about common base FET method used for I2C 5/3V3 shifting.

simulate this circuit – Schematic created using CircuitLab

My only idea is to use resistor and 3V3 zener diod but it will leak current which I dislike as it's battery powered circuit, use MOSFET transistor used with Vgs=5-10V, Vds=3V3 (but FET Vgsmax is normally 8V and I'm not sure about Vgs/Vds/Id diagram) or use an operating amplifier powered 3V3 with 12V tolerant inputs (if any).

Any idea how to do it simply and efficiently ?

Edit:
Level shift with Schottky diode blocking higher voltage in high state and small enough forward voltage (Vf@D2 + open Vce@Q2) to fill requirment for low state at input pin.


texts: Why to use Siemens to measure high resistance?

texts:
I have a Fluke 87V and I can see lots of EEVBlog videos were Dave measure high resistance values, and instead of using the Ohms range, he goes to the Siemens range (nS actually).

My question than is, why the multimeter shows this big values in Siemens instead of Ohms? Is it a standard or something? Or there is more to it, like speacial math?


texts: How do I convert 1/3 to signed float 8 bit?

texts:
The formula is as follows:

(-1)^[signed bit] * (1.[significant bit]) * (2^[excess bit -3])

or

(-1)^[s] * (1.[f]) * (2^[x-3])

It is a question posed by my signals and systems instructor, hence the electrical tag.(electrical engineering tag is two letters and not available)

The signed bit (s) has a maximum of 1 total bits. This represents the sign of the decimal. The mantissa has a range of 1-2 and the significant bits has a decimal range of 0-1. There are a maximum 4 bits in f and 3 bits in x.

I can only assume that it is not possible to represent 1/3 exactly using 8 bits, given that 1.f > 1, x < 3. That is the only way to represent the final tally as < 1. The sign is positive, so the signed bit is 0. By tabulating -1> x < 3 with f = .125, .25, .5


texts: The way I want it to work is to slowly discharge the lipo down to storage voltage and then stop. I think the best way to do this is to use a TL431 to control the voltage shutoff and use a power resistor and status LED as a load. I don't really understand completely how to calculate the proper resistor values. I have done a few calculations and gotten what I think are the right values, but I wanted a sanity check. Below is a image of the schematic I have drawn.


texts: Bandwidth of inverting and non-inverting op-amps

texts:
If the same op-amp is used in both inverting and non-inverting modes (with same closed loop gain using appropriate resistors),
will the closed loop bandwidth of the op-amp in both cases be the same?

For example,

Now, if I assume unity gain frequency = 10 MHz,
is the bandwidth for both 5 MHz?

If I am correct, then
why is the GBWP of the closed loop inverting op-amp less than that of the non-inverting counterpart?


texts: How to amplify a tiny signal riding on a large common mode square wave

texts:
I have a small signal of about 10uV-100uV riding on about 1V common mode. I have tried to depict this in the picture. I am interested in designing a board level circuit(cannot use a commercial lock-in amp) that can amplify the 10uV-100uV signal to more measurable levels that my ADC can support (say 10mV). The blue signal is a clock and the orange signal is output from a single photodiode when exposed to two different wavelengths of light. What's the best way to accomplish this? I am quite open to the choice of pulse width as depicted by the dashed blue lines.

Note: Consider the blue to be a TTL logic clock signal. The y axis scales for blue and orange aren't the same.


texts: Is this a good design for a variable power supply?

texts: Alright, so I've been studying designs and I saw designs that are far more sophisticated that's why I tried making my own design. I'm not an used to these kind of stuffs yet since we've just began studying circuits that's why I wanna ask if this kind of design works.


texts: Why is my Transformer pulling so much current?

texts:
I have taken a microwave oven transformer and removed the 2nd winding which originally put out 2000 volts.  I have rewound the 2nd coil to produce 21 VAC which I then  rectify and smooth with 2 large capacitors. I am going to use this transformer to make a variable voltage power supply, but noticed that it gets pretty hot. I have added a large heat sink with multiple cooling fans, and it still climbs in temperature a little more than I like.  I decided to check how many amps it was pulling from the mains outlet (120vAC) with no load on the secondary. I was surprised to see that it was pulling just over 10 amps.  I know transformers have a no load current on the primary but I did not imagine it would be anywhere near 10 amps.
So my questions are...
Is this normal for a transformer?

Why is it pulling so many amps with no load?

Is there a way of lowering the no load current without sacrificing useable amperage from the finished power supply?

P.S. I am just a hobbyist who is doing this project mostly to learn things in the process but does plan to use the power supply for simple things around the shop. Please keep in mind when giving very technical answers, that I have no formal education for electronics, so explanations are appreciated.


texts:
I'm debugging a PCB which has a AT Mega 128L and two CPLDs mounted on it. The microcontroller actually works OK but I'm unable to program it via JTAG (and I don't have ISP or any other headers on the board). I was obviously able to program it earlier.

When the problem began, I checked for continutity between all JTAG pins. The Reset pin was problematic and I soldered a wire onto the Reset pin and connected the other end onto the JTAG header. I assumed this would have fixed the problem, but nope. I still get the same error: Failed To Identify Target.

But while doing the continuity checks, I came across something more alarming. The meter told me I had continuity between my 3.3V rail and Ground! Not only that, it also beeped when I checked for continuity between 3.3V and 1.8V. I am quite sure that a large current is not flowing because the power supply isn't hot - I know I should have measured it but I had to leave work for other purposes. But none of the chips on the board are hot either.

My colleague whose working with me on this board told me this is actually normal and its actually because the some pins are internally shorted in some of the chips. He doesn't seem to think this could be the cause for our JTAG problems. I'm quite skeptical of this claim because when is it good to have continuity between Vcc and Ground?! But I am quite inexperienced with such things and hence I'm asking this site. Is it normal to have such continuity?

Note: I know that capacitors will intermittently give a beep but once charged, its essentially an open circuit. In this case, I've held the DMM leads onto the pads for for quite some time and it gives a continuos beep.


texts: Is there any possibility of dissecting a microchip to get data from its internal memory?

texts: There are many devices that perform various cryptographic operations inside their microchips. One of their key feature is that the secret keys are stored inside of the hardware and never leave it. Since it is possible to reverse engineer a chip, I am wondering if it is also possible to get at the chip's internal memory as well to steal the data stored in it?


texts: Inverting op amp gain using high value resistors and using oscilloscope measuremnts

texts:
I built an inverting op amp circuit as shown in above figure using varying values for Rf and Rin.

When I used Rf=10kohm and Rin=100ohm, my measured gain (using national instrument's virtual oscilloscop) was 98.88 which is very close to the expected gain of 100.

When I used Rf=1Mohm and Rin=10k, my expected gain was 100 but the measured gain using the virtual oscilloscope is only 89.99. In addition, using a real physical oscilloscope (AGILENT DSO-X 2012A), my gain turned to be about 67.1 and was fluctuating a lot.

I read that higher resistor values result in higher noise as I had seen in the measurements but why are the measurements using the physical oscilloscope so much noisier and the gain so much lower than the virtual instrument one? And why is it that for the same expected (calculated) gain, using resistors of high value result in lower gains relative to using resistors of low values? Is it right for me to believe that having more noise should not affect the gain produced but will merely make the readings fluctuate?


texts: Can you power a LED with a lower tension but the right current

texts: Can you power a 50w LED that by the datasheet needs 30v and 1.5A with less than 30v but 1.5Amps?


texts: Does a self-powered USB device have to connect to VCC from the host port?

texts:
A self-powered USB peripheral provides its own power, so is it okay to connect just D+, D- and GND to the host port, or do you always have to connect +5V as well, then wait for the negotiation phase for the device to tell the host that it is self-powered and therefore doesn't want any power, thank you very much?

The specific peripheral I'm looking at is based on an FTDI FT4232H USB-to-serial adapter, but I'm really hoping for a generic answer to the question.


texts: Sourcing a Relay for AC Power Loss on UPS

texts:
I have a system outdoors (~200W) that is powered from the house with a battery backup on UPS. When the UPS switches over to battery power, there is no way to currently generate a notification that the main power is lost.

The system has a LTE connection and a Raspberry Pi. I'm wondering if there's a relay that could sit between the AC power, and use the GPIO of the Pi to send a notification that the UPS has switched over?

What kind of relay should I be looking for? What things do I need to consider?


texts:
simulate this circuit – Schematic created using CircuitLab

I want to find out the thevenin equivalent of the circuit across 20 micro farad capacitor as a load. I calculated the thevenin resistance which came out to be 1.5 k-ohm. Is it correct? Actually I am confused with the thevenin voltage across the capacitor. I forgot the concept of supernode which I think will be used in this circuit.

I need the thevenin circuit of the this circuit across the capacitor. Please help and please do confirm my thevenin resistance. If someone can post the full solution, it would be of great help.

Thanks in advance!!

EDIT: Some people are saying that I have done no efforts in solving this circuit, below are my calculations which show how I got the thevenin resistance of 1.5 k.

So, if I short the voltage sources and open the current sources the circuit reduces to,

simulate this circuit

Where node A and B are where the capacitor was connected.

Since node C and node D are same nodes, the 12 k resistor is redundant. Or you can say that 12 k is in parallel with an ideal wire and thus the net resistance is 0, and thus nodes C and D are joined. Hence, the circuit further reduces to;

simulate this circuit

The thevenin resistance thus came out to be 1.5 k. Is it correct?


texts: A passive sensor does not need any additional energy source?

texts:
I am currently studying the textbook Handbook of Modern Sensors - Physics, Designs, and Applications, fifth edition, by Jacob Fraden.
In this textbook, the author states the following:

All sensors may be of two kinds: passive and active. A passive sensor does not need any additional energy source. It generates an electric signal in response to an external stimulus. That is, the input stimulus energy is converted by the sensor into the output signal. The examples are a thermocouple, a photodiode, and a piezoelectric sensor. Many sensors are direct sensors as we defined them earlier.

In researching this further, I came across this Quora question, in which user Giulio Moro claims the following:

An active sensor would be like your garage door sensors. One side has a light and the other a sensor. A beam fires across the area when the doors closing to ensure it's clear. If the light beam is broken, the door stops, and then opens wide.
A passive sensor would be like a metal detector. It creates a field, and when anything crosses it, it makes a sound based on the type of obstruction. A low pitch for say a plastic bottle or piece of wood, and a high pitch for a metal object.

There are two aspects of this definition of passive sensor that slightly confused with:

Firstly, what is meant by an "additional" energy source? And analogously, if there is an "additional" energy source, then what would the base/default energy source?

I think that this second confusion likely stems from the first, and clarification of the definitions of an "additional" and base/default energy source will probably clear this up, but I want to ask it anyway just in case. From a physics standpoint, I'm not totally convinced of this definition of passive sensor. In particular, I'm struggling to come to terms with this idea that a sensor can function without an energy source (although, again, the text does say additional energy source). The example of the metal detector also seems unconvincing, since my understanding is that metal detectors are certainly connected to some energy source (say, at airports or such)?

I would greatly appreciate it if people would please take the time to clarify this.
EDIT: After reviewing the answers (thank you all), one thing is obvious: There is a terribly large amount of contradiction with regards to what sensors qualify as active or passive.


texts:
I've got 8 ds18b20 (knock-off I assume) temperature probes monitoring the temperature in a freezer. I'm outputting the value of those probes each minute to an RRDTool graph using a Raspberry Pi.

However, occasionally I get some very strange readings and was wondering if anyone here would be able to help me figure out why.

Here's a graph for one of the eight probes (they're all pretty much the same):

AS you can see there are 8, somewhat evenly spaced spikes in the graph.

The interesting thing is that I have 2 other probes also connected to the same 1-wire network that are just outside the freezer. They do not have any spikes at all:

The probes are hanging in free-air inside the freezer, not touching any surface.

Initially I thought that maybe there was some sort of electrical interference, maybe caused by the freezer's compressor. And this may still be the case, I'm not sure, but the fact that the 2 ambient temperature probes don't show any affect indicates to me that it's probably not interference. The external probes are pretty close to the freezer as well.

Also there's the fact that immediately after the spike, the temperature doesn't return to the value that it had before the spike, but seems to be cooling down and slowly leveling out as it reaches the freezer's set temperature.

I'd like to rule out electrical interference before continuing my investigation. If anyone knows whether this is possible, I'd really like to hear from you.

Some more information that may help:

It's a chest-freezer, It's not in optimal state as there's a small "leak"(?) there's water around it's base, I use old cardboard to absorb the water and it usually evaporates from the cardboard quite quickly.

EDIT:

So it looks like it's a daily thing. Here's some more graphs for the same sensor:

I'm guessing that this is just a 'feature' of the freezer, and even though it looks highly inefficient, I'll just have to live with it.


texts: How to account for differences in measured DC resistance of motor winding

texts:
I have five small brushless DC motors from KDE, model# KDE2315XF-2050.  The specs for this motor state that the winding resistance is 0.034 Ohms,
and having conversed with KDE, they state the winding inductance is ~3.6uH as measured with a scope at 150kHz.
I want to verify these values, and according to KDE they use the method outlined in Tektronix's document "Capacitance and Inductance Measurements Using an
Oscilloscope and a Function Generator", document ID 75W-28152-1.
KDE modified some of the variables in their example video on YouTube such that the voltage amplitude is 2.5V, and the test frequency is 150kHz.
I performed this test myself using a value of R reference being measured at 995.9 Ohms (using a calibrated Fluke 289 multimeter), freq generator set at 2.5V amplitude and 150kHz.  I then measured the
windings of 5 motors.  The following are the average results for all five motors:
Average Inductance = 3.46uH

Average Resistance = 0.5972 Ohms

When I measure the DC resistance of all five motors using the Lo Ohms setting of the Fluke 289 I get an average resistance reading
of:
0.031 Ohms.

Using the scope and the I-V method the inductance jives with the specs, but not the resistance.  I trust my multimeter to provide an accurate DC resistance measurement.
If I adjust the voltage amplitude and frequency to 5V and 50kHz I get:
R = 0.08584 Ohms
L = 3.814uH

So my question is this, why is there such a difference in the winding resistance between the two methods of measurement (scope vs. multimeter)?
As an FYI I do not have a high end scope of function generator, so I do expect a difference but not so much.  Also note it has been 20+ years since I have worked with electronics at
this level.  If I am missing something please forgive me.


texts: How can I get the total resistance in this question?

texts: How do I get the total resistance here when there are two terminals A and B?


texts: Designed an electronic circuit using APR33A3. Not working

texts:
Designed an electronic circuit using Datasheet of APR33A3. It doesn't work.
Checked the connectivity between component and it seemed fine.

I have given a 5V DC supply
Using an electret microphone
8ohm impedance speaker

Looking for suggestions
Link to the datasheet http://www.mycomkits.com/reference/aPR33Ax_C2.1_Datasheet_2130219.pdf
Link to the video of circuit made by me
https://www.youtube.com/watch?v=I2_Uu9zhqMg


texts: SD card suddenly stops responding to CMD0 (RESET/SPI)

texts:
A device I had been testing for over two months suddenly started giving FR_DISK_ERR (I'm using Elm Chan's FAT-FS) [Link]. When I tried debugging, the command (CMD0) which must be clocked in to set the SD card into SPI mode (as described in the SD card spec sheet - SDcard.org [link])  return 0xFF and not 0x01, i.e. it failed.
My question is:

*If CMD0 fails does that mean the SD card controller is not working?

*Will it still work in SDIO mode even if CMD0 fails? (I couldn't test it as my uC does not support SDIO)

*Can an OS (Linux, Windows, Mac) format this SD card to make it working again? If so how does it do it?

Chan's FAT-FS has no method to solve if we have an FR_DISK_ERR, so I need to find a way to solve this remotely.


texts: Capacitor with Current Source in parallel with a resistor

texts:
[![enter image description here][1]][1]
I know that in a current source in series with just a capacitor (without the parallel resistor), it would charge until forever in an ideal case with the fomrula

I= (dV/dt)*C

but in this case since it is in parallel, the capacitor in t=0 will start with 1mA but it will be decreasing so I couldn't use the formula above and neither the Vc=Vi(1-e.....) either since no resistor in series or voltage source.

so I know the current will decrease (but can't know the slope since its variant) and that the voltage will  increase until 1V( 1K*1mA). but I would like to know the formula for it so I could know the timing for other similar cases.
THANKS SO MUCH for your time!


texts: Unmatched connectors on condenser mic and wireless belt pack - make adapter?

texts:
So I want to buy a Shure Earmic (condenser) which has a mini XLR connector with 4 pins, one of them in the centre. And I want to connect it to an AKG PT40 body pack which has a three pin mini XLR connector. I tried plugging one in directly and it doesn't work. I figure the problem is its how its wired.

Shure pinouts:

 1. Shield
 2. Connected to pin 3 via 2.2K resistor
 3. Connected to above resistor via 1uF cap
 4. Not connected

PT40 pinouts:

 1. Shield
 2. Audio (inphase) and +3.8V
 3. Audio

These connection schemas come from the online manuals. My guess is that the bias voltage on the Shure mic is supposed to come in on pin 3 via the cap. Or am I wrong?

What I am thinking of doing is getting a male and female connector and a three inch long piece of shielded cable, and simply making up an adaptor.

Can this logically work?


texts: Could someone identify this old prototyping board?

texts: A friend of mine had this lying on a shelf- he had found it while cleaning out his basement. Any idea what it is meant to slot into, or its purpose in general?


texts:
I have a couple of these FT232RL breakout boards direct from China, look like they are Folger boards.  I measured the voltage between Vcc and GND, and it's 5V from the factory.

It has 3.3V pad on the back.  I'd like to change this to a 3.3V.

So do I solder the 3.3V pad to the center pad?  Do I have to make a cut across the 5V trace?


texts: How does power remain constant when powering devices at different voltages?

texts:
As per the below image, increasing the voltage in a circuit with just a resistor results in an increase of current and therefore power.
However if I have a circuit where I am just powering a DC device (say a Wifi Router) which can operate on 12-24VDC, the higher the voltage supplied within that range, the lower the resulting current.
I know the power is staying constant so mathematically it makes sense. It also intuitively makes sense - the router only needs a maximum of 12W to operate, therefore the higher the voltage supplied, the lower the current that is required to generate the energy needed to power the router.
What I don't understand is what is this router doing to reduce the current at higher voltages? Why isn't it acting like a resistor?
Thanks
edit: fixed diagram, thanks user253751


texts:
I am not entirely sure whether this question would be on-topic here, but I am stuck on this issue unable to find any relevant answers online in any other sites.

I am working on a pet project which includes using SPI NOR (I am going with 16MB Winbond W25Q128 SOIC-8 chip). This chip will be used for bootloader storage.

Now I got my hands on STM32 based programmer for SPI chips (SOP8-SOP16, see pics below). However this programmer seems to work only with software provided by whoever designed it, which is only available on Windows XP (attempting to run it on Win7 results in it working, but machine complains about libusb drivers that it installs). I do not have any Windows machines, I mostly use Mac since it was enough before (I also have a few headless Linux boxes at my disposal). But Mac (nor Linux) do not recognize this programmer.

So my question is what are inexpensive programmers that I could easily use for writing/dumping SPI memory on Mac or Linux? (I have read that dediprog ones work on Linux, but their price-tag is way out of my budget).


texts:
I bought a cheap RC Submarine. Similar to the cheap RC Helicopters it's charged via a cable from the Remote Control. The Remote Control is powered via 6 AA Batteries. --> Here's a picture of the Charging Setup

Question: I lost the charging cable and since it's a cheap device I'm not able/willing to reorder one :-). But since I'v got the correct type of connector for the Remote Control Site, I was wondering if I can just solder one with some jumper cables that fits the port on the submarine site.
If one of you could tell me of those 4 pins on the submarine is + and -.
I think there are 4 Pins to submit the charging state to the remote control (light goes of if fully charged). Is it feasible to just connect two Pins (+ and -) to the charger and ignore the other two?

On the Submarine Site, the charging port consists of 4 pins.
Here's a picture:

By closing the hold the pins connect as showing in the picture.

Additionally, here's a close up of the black framed part in the upper picture:


texts: Diode Drop vs Open Drain Output Tolerance

texts:
I have an LED Driver IC that states a 5.5V tolerant Open Drain Output. It's Absolute Maximum section indicates 6.5V with a note saying "The input negative-voltage and output voltage ratings may be exceeded if the input and output current ratings are observed." The outputs can drive LEDs directly or be used as open-drain GPIO.

Typical Application:

My question is, how does a diode's forward voltage drop affect this? If I have a led strip segment of 3x 3.3Vf Leds + 100Ω Resistor in series and a 12V supply, shouldn't the voltage drops from the diodes bring the output within tolerance? Or not? Why?

simulate this circuit – Schematic created using CircuitLab

Note that the current through the port is 20mA, half of the max recommended 40mA (Absolute Max is 50mA and a clamp current of ±20mA) per output and 200mA per port.

Edit: Found TI: Understanding and Interpreting Standard-Logic Data Sheets

  Output Voltage, VO
  This is the maximum voltage that can be applied safely to an output terminal, with respect to the ground of the device.
  Helpful Hint:
  If there are clamp diodes between the device outputs and the VCC supply (see Figure 20) for ESD protection or parasitic current paths in the output p-channel pullup transistor, the positive absolute maximum rating for the output voltage is specified as VCC + 0.5 V. This ensures that there will not be enough voltage applied between the output and VCC to forward bias the clamp diode and cause current to flow. You may exceed the negative rating if you ensure that you are not putting too much current through the ground-clamp diode. The maximum current that you may put through the ground-clamp diode is specified in the IOK absolute maximum rating.

As the IOk rating is 20mA, and the normal ON state current would be ~18mA, the normal OFF state with the drain left open should be a lot less, no? If the current through the ESD/Clamp Diode increases, the voltage drop across the leds and resistor should increase as well right?


texts: Charge transfer in conductors of different metals by touching

texts:
when we touch two metallic conductors one is neutral and other has excess of charges,
Case 1- Both metals are of copper, then we can calculate actual charges on them at steady state by capacitance formula Case 2- One metal are of copper and other of aluminium, and again we can calculate steady state charges by capacitance formula
Problem- If size and shape of conductors remain same then calculated charge on both cases will also be same because capacitance depends on size and shape but intuitively why this can be true? Even changing metals doesn't change anything about charge transfer which seems quite counterintuitive to me or I'm missing something? And does time constants (charging time) in both cases will change or not ?


texts: Confusion with mapping a transducer range to a different output voltage range

texts:
A pressure transducer with a range +/-200Pa has both serial and analog outputs.
I'm only interested in positive pressure besides sometimes the negative pressure needed to be measured when there is negative pressure offset. The pressure transducer DAC converts the serial to analog voltage output. And for some reason the voltage output needed to be used.

Currently the analog output is set to 0-10V and it means 0 to 200Pa pressure range corresponds to 0-10V voltage output range. But in this case sometimes negative pressure offset even small is outputted as zero volt which affects the measurements. This cane be seen in serial output but not analog output because the minimum is 0V for analog output. I dont want to track and zero this offset  each time for automation reasons.

For a workaround I can set the range such that -200Pa to +200Pa will correspond to 0-10V and where in this case +5V to +10V will correspond to 0 to 200Pa.

I could only upload the manual here.

And here is main specs:

So to summarize currently the range 0 200Pa is mapped to 0 10V; but if I change the settings, it that case 0 200Pa will be mapped to +5V to +10V. In that case I can measure negative offset, but my confusion is how to quantify or expound on this change in terms of resolution.

0 200Pa was set to 10V change and now 0 200Pa will be set to 5V change.
What does it change comparing to the previous matching in terms of precuson or resolution? Am I losing resolution here or anything else? What specs I need to focus on? Or do I need the analog output resolution?


texts: Can I use a pc case fan for a tumble dryer?

texts:
My tumble dryer is broken. I found the service manual online and according to the error number the heat pump fan is the problem. I open it up and to my surprise I found a standard sized case fan in 92x92x25 dimensions.

It is labeled with: NMB-mat 7 3610VL-04W , 0.40A, 12V. The error message says that the fan is below 1200 rpms. Which is quite true because it doesn't work at all. So my question is:

Is it possible to use a standard 92mm case fan? The Voltage is also 12V but how about the amperage? Does it have to match?

I would buy one with a 3 pin plug and replace it with the (proprietary?) one of the original. It needs to thave more than 1200 rpms of course. I found the original spare part however in another country and quite pricey...


texts: How can I determine the resistance needed to heat a wire to a specific temperature?

texts:
Possible Duplicate:
  How do I calculate the temperature rise in a copper conductor?

I want to have a AA battery heat up a copper wire .12mm diameter, but want it to heat up to 302°F, not any higher. What resisters do I need to use, and any other suggestions?


texts: In my circuit, RFID card sometimes works sometimes not. it depends on how I put the card on RFID receiver. Usually it does not work when I put around the smps transformer. I guess SMPS transformer affect RFID card. I cannot change transformer and RFID receiver location. What do you suggest to remove SMPS transformer effect?


texts:
When is the best time to read the bit out of a serial data output 12-bit ADC chip. The chip is a AD7476A, and here is the datasheet AD7674A Datasheet.
Going by the timing diagram, when is the best time to read the output bit during the SCLK clock, the falling or rising edge? I think the falling edge of each clock cycle from 4 to 15 should give the 12 valid data bits out provided the timing is correct?
Below is an image from the datasheet of the timing diagram, with the description of the serial interface.

EDIT 1
Thought I would provide an update as to my development of the timing to read data from this ADC chip. I have simulated my code with a testbench and the waveform diagram can be seen below. I continuously clock the ADC chip SCLK pin at 10 MHz as you can see. I shift the data input into the shift register on the rising edge of the SCLK clock, and after 16 clock cycles when CS goes low, I store the 12-bit register value into another register on the falling edge on clock cycle 16. Then on the next rising edge I bring CS high again and this repeats.
The next two images show the design being implemented on hardware, although as I haven't got the ADC chip yet, I am testing with the pin either pulled high or grounded. You can see the two images reading either 4095 or zero with the 12 LEDs on the board representing the stored shift register value at all times.
I will provide an update when I get the chip as it will be probably take a bit of testing to get it to work.

EDIT 2
Ok so I have connected the ADC chip to the FPGA with the CS, SCLK and SDATA pins. The FPGA is powered with 5V and the on board 3.3V from the FPGA powers up the ADC chip circuitry. I m reading the 12 bit output from the chip on a 7 segment display.
First attempt sort of works. However when I turn the pot to low (or 0V analog input to ADC chip, the result is 103. Something weird happens as I turn the pot up. Once I reach halfway pot position, the 12 bit value is 4060 and once I go past that the the ADC value jumps back to zero.
Then as I continue to turn the pot up to the max position (3.3V input to ADC chip), the 12 bits are around 4000.
Any reason as to why this jump back to zero. The bits don't seem to increase by 1, but maybe 6 or so, although it is impossible to turn the pot so finely.
Where would you folks start to debug this? I have a power supply arriving tomorrow so I can input exactly between 0V and 3.3V to see the LSB changes to make sure my interfacing is ok.


texts: single phase AC motor not starting with random SSR (blind control) when all wires are connected

texts:
I'm using 2 AQG22205 (see datasheet) to control my blinds.
I can let the blinds go down when the up wire isn't connected and vice versa.
But as soon as I connect both wires, the blinds won't move.
I have no clue as to why this is. It seems like this should work. Does anyone have an idea what could cause this behaviour? Or am I missing something? The blinds itself are the Ilmo 50 WT (between 0.4 and 1.1A, depending on size of blinds, see limited datasheet). They do have intelligent obstacle detection and frozen detection. Could this be interfering, as the SSRs have an off-state leak current of 1.5mA?
The SSRs have a max load current of 2A and a max repetitive surge current of 15A (non-repetitive 30A).
I coupled them with a 100R (3W) and 0.1uF snubber.
I've attached a simplified version of the circuit I'm using (removed xor and and logic preventing activation of up and down).
In this case, the motor only works, when the up wire, or the wire with the cross is disconnected.
I measure 230Vdc (DC!) over both SSRs (1&2 and 3&4) when I'm not trying to move the blinds. When I try to move the blind down, I measure 1V between 3&4 (as expected) and 5V between (1&2).


texts: Can I use two LED in series without a resistor?

texts:
I need to put quite a few LEDs on a PCB, and I want to reduce the number of components.

The LED I want to use is NCD0603G1, which has a forward voltage of 2.6V to 3.6V (documented.) I have a 5V power supply.

I have a few questions regarding this:

Since 2XLED voltage is ~5V, can I use it without a resistor (I tested this and LEDs did light up.)
I checked thevforward voltage using the diode voltage function of a  multimeter, that shows a voltage of 2.3V, why is it different from the datasheet? Is it common?.
If putting it in series without resistor is not a good idea, can you please suggest a recommended method?

I am quite new to electronics, please let me know if anything is wrong in the question itself.


texts: Creating mobile LED projects with LED strips, USB, and an 8xAA battery pack

texts:
I'm trying to make some LED clothing.

I'm planning on buying some LED strips, which require a 12V power supply. I plan on buying some battery packs for the power source. To link the power source to the lights, I plan to use these USB ends that I happen to own that look like this:

I took this out of a mobile phone charger power bank type thing.
I then plan to plug a 1-4 USB input hub into the USB so I can power multiple separate things. I own this one and plan on using one that came with rock back about a decade ago.

Then because I own so many micro USB cables, I want to plug the USB end into the hub, cut off the micro-USB end, and solder the wires onto the LED strips

Is my logic sound? I've never really done anything like this before. I've heard that USB hubs might convert the 12V to 5V. Is there other wiring would make more sense for what I'm doing? The main thing I need is for one battery to go to about four devices. I couldn't really figure this out.


texts:
Right, I'm new to electronics, but this is what want to know:

What do I need to take a mic input, and output it to some ear phones (standard jack, can be mono). I want to build a motorcycle intercom, here are some other requirements I have in mind:

Volume controllable
Turned off by a switch

Also, if I have two inputs that I want to send to one output, is it as simple as joining those two inputs together and the connecting with output? Perhaps with a few diodes... I'm starting to guess here.

Anyway any advice to nudge me in the right direction would be appreciated.

Thanks, Ben :-)


texts: Only half of the IrDA packages are received correctly

texts:
I have a STM32F765ZITx as master and a STM32F051C8Tx board as slave that im trying to communicated with each other over IrDa. The master is sending 6 bytes (2 startbytes, 1 length of data byte, 1 databyte, 2 checksum bytes) to the slave, which works as a request that the slave is going to transmit back to master a standard reply message containing 14 bytes of data (19 byte including header and checksum). Master transmits every 100ms. My problem is that the slave is receiving the correct header every two samples. This is the situation:

sample 1: 254 251 1
sample 2:  0  251 1
sample 3: 254 251 1
sample 4:  0  251 1
sample 5: 254 251 1
   .
   .
   .

So the slave is transmitting the standard reply back every two samples.

Here is my init of IrDA on both boards:

static void MX_USART1_IRDA_Init(void)
{
hirda1.Instance = USART1;
hirda1.Init.BaudRate = 9600;
hirda1.Init.WordLength = IRDA_WORDLENGTH_8B;
hirda1.Init.Parity = IRDA_PARITY_NONE;
hirda1.Init.Prescaler = 10;
hirda1.Init.PowerMode = IRDA_POWERMODE_NORMAL;
hirda1.Init.Mode = IRDA_MODE_TX_RX;
}

In my HAL_IRDA_RxCpltCallback(IRDA_HandleTypeDef *hirda) function on the slave side I have a function that handles the received data and calls HAL_IRDA_Transmit_DMA(); to send the standard reply back , before a new HAL_IRDA_Receive_IT(); is called again. I'm not very experienced in this so I am not sure what the "magic" behind these HAL functions do.

Is it bad to call these functions in this order? Are there timing issues when calling transmit and receive in the RX callback function? I have checked that the HAL_IRDA_Transmit_DMA(); is never returning HAL_BUSY. If I remove the transmit function it receives fine.

Anyone have suggestions on why it behaves like this?


texts:
I have some inexpensive audio equipment that I am willing to experiment on. Trying to cut down on cables and I would like everything to be USB-C. I have a small midi keyboard and a small audio interface that both use USB-B. Is there any USB-C female to USB-B cable I could buy? I would even be willing to desolder the USB-B jack and replace it with a USB-C jack as long as I can figure out the wiring.

I tried looking online, but I didn't see anyone selling USB-C jacks or a USB-C female to USB-B adapter. I did see some USB-C male to USB-B adapters, but that defeats the purpose since I want to be able to connect everything with a USB-C male to male cable. Any suggestions?


texts: Super new to doing electronics projects.  I have a project where I have attached 12 led lights in parallel to a small plastic tree.  The whole thing rotates on a motor.  I am using a 3v CR2450 battery to power the whole thing.  The lights dimming and eventually turning off completely within 10 mins of turning it on.  I would like it to run as long as possible and with ultimate brightness.  I am using 3mm yellow led lights and a geared motor.  How do I figure out if I am using the correct power source and if so what should I add to my circuit to make it work properly?


texts: Is it a misconception that feedback into inverting terminal of opamp is negative feedback and feedback into noninverting terminal will be positive feedback? I feel it is. Because all oscillators have feedback into inverting terminal and still it is called regenerative feedback.


texts: What is a 'normal' resistance level for a closed switch?

texts:
In a closed contact or a closed switch, theoretically, the resistance should be zero, but in actual measurements the resistance is very close to zero but not zero.

So my question is:

What is a 'normal' resistance level in a closed switch (let's say a Push Button that works with mA currents) before it needs to be considered as useless due to corrosion etc.

Edit: The switch I'm talking about is a Push Button with integrated LED. Attached Image with schematic for more detail.


texts: Impediance mismatch and amplifier question

texts:
I am converting an aviation headset to take a Bluetooth signal.

The headset speakers are \$150\Omega\$, and the Bluetooth adapter I think is \$10\Omega\$. The mic will not be used.

Can anybody recommend a solution? I prefer a circuit that can run off the Bluetooth \$3.7\$V battery (\$250\$mAh).


texts: 28V Stepdown with TracoPower TRN 1-2411 DC/DC converter for ESP8266?

texts:
Im new to electrical engineering. For a project I want to supply an ESP8266 with power by using a  28V Milwaukee Battery. My Question is:

Can i supply the esp at the VIN PIN using the 2411?


texts: Why is a tantalum capacitor recommended?

texts: I am looking at the datasheet of an accelerometer (ADXL345), and in the power supply decoupling section, it says to use a tantalum capacitor. Why is this recommended?


texts: Where to decouple battery in circuit with power switch?

texts:
My design is kind of a timer, and it will be turned on and off constantly by a switch, cutting power to an Attiny85.

The Attiny is programmed with sleep mode, and draws only 4.4 uA.

In the first circuit, when I turn it off, it still draws power from the capacitor, for about 10 seconds. So, if I turn it back on while in that 10 seconds, it continues where it left. This is not wanted.

simulate this circuit – Schematic created using CircuitLab

Is this second circuit the solution? Or it's not recommended due to not be really off?

simulate this circuit