texts: TLC5940 resets itself when driving certain DC motors

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So I had the following setup:

I was just driving a small DC motor with this circuit by either sinking current on pin 0 or 1 on the TLC with a motor voltage of 5 volts and everything was fine. The motor was drawing around 200mA and I thought I could upgrade the motor a bit so I picked one that drew around 350mA at 5V. After I connected the motor and powered the circuit the motor just twitched for a split of a second and then nothing. I changed my sketch and reset the TLC every 5 seconds and it turned out that the motor was just doing this every time the TLC tried to drive it in one direction.
I added ceramic capacitors between VCC and GND on the TLC and the H Bridge and electrolytic ones at the motor supply pin of the H Bridge but that did not help. Then I replaced the H Bridge with a beefier one, the L298 but that did also not help. Now I tried the circuit with a PCA9685 instead of the TLC5940 and it seemed to work now... but I was still wondering why it was not working before. I saw oscillations on my scope right in the moment when the motor tried to start that were driving the logic supply voltage of the circuit to almost 1V both times, when I used the PCA and the TLC, the PCA just seemed to "survive" this voltage drop and just continued working without needing to be reinitialized. Maybe because its minimum supply voltage is lower but I am not sure since I was not using a decouple capacitor on purpose. I understand that the motor draws lots of current when  starting up, but I expected the drop on the motor supply voltage and not on the logic supply, I intentionally used different power supplies, both with an isolation transformer. Only the grounds in the circuit are tied together.
It is not visible in the drawing, but the power and ground rails on either side of the breadboard were connected. Also, I understand that the PCA is push pull and the TLC is open drain, I used the pull ups only for the TLC.
I am just wondering what is happening here or how I can prevent it because I really want to use the TLC over the PCA... I am happy for any solutions/ideas/opinions!


texts: How to read multiple I2C sensor (MLX90393) data on ESP32?

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I am using MLX90393 Triaxial Magnetometer Sensors for my project. They communicate via I2C. I am using an ESP32 and coding on Arduino IDE. I found this code on GITHUB and was able to read from ONE sensor successfully. However, I am doing a project to use FOUR of these sensors. My sensors have a custom-made PCB board and I am aware that each sensor have different addresses (manually configured through soldering). I am also using 2 pull up resistors to get reading from ONE sensor, which I am only able to do until now.

However, I am struggling to understand how the code works and as a result not able to change it accordingly to make TWO or FOUR of these sensors work together. My goal is to keep reading data simultaneously from FOUR sensors via I2C (SDA,SCL,Vcc,Gnd), transfer the readings over Wi-Fi and finally, once one of the four sensors is touched, display data from that specific sensor only.

Also, if you know a good way to visualize X,Y,Z axis data, please do suggest.

Thank you in advance for your kind help.


texts: Phasor Representation of Sinusoidal Forcing Functions

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Lets take a phasor Vm<\$\theta\$  which is equivalent to Vmcos(\$\omega\$t + \$\theta\$)

Let us Assume that a forcing function on a network is  Vmcos(\$\omega\$t + \$\theta\$) +j Vmsin(\$\omega\$t + \$\theta\$)

This can be written as  Vm ej(\$\omega\$t + \$\theta\$)    by Euler's relation

simplifying this gives  Vme j\$\theta\$  .e jwt

which further can be written as   V e j \$\omega\$ t  where V is a  defined by Vmej\$\theta\$

My question is : are  both V and  Vm<\$\theta\$  Equivalent?

My book  implies that they are equal.

Correct Me

2nd Question How are Phasors Complex numbers?


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I am trying to make an IR transmitter, and have the following set up:

simulate this circuit – Schematic created using CircuitLab
I was thinking of this circuit, because I want to run through the LED ~700mA with 20mA output from the microcontroller. And putting R2 at the collector would mean a lot of power wasted by R2, doing this I am hoping to minimize that.
However the problem is I want to put the BJT into saturation mode of operation using this configuration. I found this table on wikipedia, that shows what voltages should be applied to what contant for different modes of operation:
I can understand the table, but have problems calculating the resistor values. Here's what I do know (for saturation):

Q1 collector current \$I_c=700mA\$
D1 voltage drop \$V_f=1.4V\$
Q1 CE voltage drop \$V_{CE}=0.3V\$
Q1 BE voltage drop \$V_{BE}=0.95V\$

Using these values how can I calculate resistors needed to put the transistor into saturation mode of operation?
Could you provide more general details about the calculations, that could work for any mode of operation.


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I'm making an interface board using FT2232H in sync mode with a small FPGA, and thought how everything could be much easier if I can just use FT2232H as my clock source. Unfortunately I need different frequency and deriving my clock from 60 MHz would be way too much trouble.

So... can I swap 12 MHz crystal for something between 6 and 12 MHz or is it somehow tied to how USB works?


texts:
I'm doing some kind of reverse engineering to this very old power supply design. I'm having hard time trying to understand it all. I'm asking for some hints that help me read this schematic. From this circuit, you should know:

1 - The line to line voltage is 480 VAC.

2 - The input to the LM317 is +27 V as marked. Don't understand how +27V is generated in that arrangement.

3- The reference is not 0V for the bridge rectifier. It's -13V coming from the regulator.

4- The output of the LM317 (+13.25V) feeds another control circuit that I'm not showing.

5- When the coil is activated, it shut downs the main power.

What I really want to understand is how the +27V is generated, and how the FET is turned on. My guess is that when the control circuit gives the signal to the SCR, it activates the coil, but don't understand how. You can see this design is strongly dependent on the zener diodes. There are 4 zener, 43V, 10V, 12V, and 13V. How would you improve this circuit?

EDIT: The three diodes in series below the coil are TVS diodes. Each one is 300V, so the total reverse breakdown voltage is 900V.


texts: BLE IoT device as platform backdoor for hackers

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I have a IoT device that works with BLE and uses a smartphone as a bridge to connect to a digital platform (cloud).
The communication between the IoT device and the platform is based in PKI.
The IoT device has only few privileges and services to with the platform such as status communication, public key sharing and other few status messages.

If this IoT device is hacked, could it be used as a backdoor to access or change critical information in the platform?

What can a hacker do with a hacked IoT device to threat the platform data?

The hacker will not be able to access any other data than the one allowed by the platform to that device, correct?


texts: How can you damage DMM if you haven't discharged a capacitor?

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Hi, I measured capacitance on some capacitors using my UNI-T 139S True RMS Multimeter without discharging them first. To be clear, I don't even know if they were charged because they are mounted on the PCB in USB charger that I disassembled (I disconnected it from the socket and after 1 hour I began disassebling it). Later I read in multimeter instructions that you should discharge capacitors first. In instructions that I got with it, in the Capacitance measurement section it says that the multimeter has overload protection: 600V-PTC.
I am wondering what damage it can cause to a multimeter ? Capacitor values that I measured are below.
USB Charger:
90 -260 VAC 50-60Hz
Capacitor values:
470μF 10V,
4.7μF 400V
UNI-T 139S safety standards: UT139S


texts: What type of pressure or weight sensors are thin? (Arduino or R-Pi)

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I want to know if a person is in a walking path of approx. 10x1,5 meters.

I thought on putting thin tables in the path and putting these sensors under each even table (to save some money): https://www.amazon.com/Qisuw-Pressure-Sensor-FSR402-Sensitive-Resistor/dp/B07F1Q2Y6K/ref=sr_1_7?ie=UTF8&qid=1541179629&sr=8-7&keywords=force+sensitive+resistor+small

However, for a 10 meters path, it would still be expensive.

Are there other options?

Edit: Ideally I would like something like this (the sensors to build, or the floor pad already built ready to connect)


texts:
I am doing some practice problems based on what I learned today in lecture. However, I am stuck on this problem:

A 10Ω resistor is in series with a bulb and a 12V source.

a. If 8V is across the bulb, what is across the resistor?
 b. What is the current in the circuit?
 c. What is the resistance of the bulb?

Where would I begin solving what voltage is across the resistor? I do not the current, nor do I have the means to find it (that I can see), thus I can not find what voltage is dropped. I am not sure if I can assume the bulb has no resistance, in which case I can solve the problem easily.


texts: Update STM32 with read out protection level 1 over UART

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I'm not sure if it is possible, to update the firmware of a STM32 over UART, when the read out protection is set? Basically, the firmware comes encripted to an ESP32, which should then update the STM32 firmware over UART without setting the option bytes.
Further, is there a safe concept to update an STM32, such that the firmware works only on this uC? What I have in mind is something, that uses the UUID of the chip and that only works, if it matches?


texts: Charging a 1.2 V, 1000 mAh, Ni-MH battery

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I recently bought this Camelion 1.2V AA cell pack. It says 1000mAh. Now I am trying to charge them. But before I do so, I want to know the possible outcomes in three scenarios:

If I were to charge using these values then what would happen if:

1.2V but low amp for example .44amp?
1.2V but higher than 1amp?
1.2V and 1amp?

And what would high or low voltage do?

How should I charge them?


texts: This circuit has floating nodes in LT Spice?

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This is the circuit I'm working on. This circuit probably doesn't work as intended to begin with, but that's not the point.

LT Spice keeps complaining that it doesn't have a reference to ground. I get an error that says "This circuit has floating nodes."

I found this but that didn't solve my problem.

It would be one thing to just connect a ground somewhere, but that will ruin the validity of my circuit.

The voltage source defined as MAINS in this circuit is just that...a simulation of the mains. It is a 60Hz sine wave with an amplitude of 120V. If I add a ground to it, I won't get the negative part of my wave!

The resistor connected to the voltage source is there to prevent another error being thrown about having inductors in parallel with the voltage source.

How can I keep this circuit equivalent to the real world so that I can simulate without losing half my wave from my MAINS voltage source?


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I have a very basic question about VHDL. Do we need a separate .ucf file for each .vhd file or not?
The reason I am having many .vhd files because each of the entity specifies a different interface. Should I combine all of them?
For example, I am working on SPI interface of the FPGA to configure a chip, and LVDS interface of the FPGA to read output from the chip (just for higher data rate). Therefore, right now, I am having 2 .vhd files for each interface. Is that correct?
Any recommendation on which document to read would be appreciated. Thank you.


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I am trying to create a circuit that allows me to measure the maximum power draw of a USB socket. To do this I would like to put the 5V line under some kind of load and to generate high current, I need a circuit with between 5 and 10 Ohm resistor so that I can generate a current of 0.5 to 1A. Unfortunately, my toolbox is not very extensive - I have only 7 100 Ohm resistors and nothing rated below this. I have no very thin wire (that I can think of).

I have a USB charger doctor which will allow me to measure current draw on the USB socket. I have a multimeter which can help me measure the resistance of various things around the house. What can I use to create a resistance of 5 ohms in my circuit? This is a strange request I know but hoping someone will have a bright idea.


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I am trying to wire my motor (US Motors, Model: C55JXKNL-5041) to a polarity reverse switch. The diagram printed on the motor is as follows:
BLU ____L1
BRN ____INS
BLK ____INS
ORG _^
WHT _^
YEL ____L2
RED _^

There is also a note printed on the motor saying "To reverse rotation interchange RED & BLK Leads."
I am able to wire up the motor and it works properly but only in one direction. I can't figure out how to wire it so that my 6-pin polarity switch will flip the red and black leads as indicated while still properly tying together the other leads.

Here are images of the Motor and Switch that I'm using. Hopefully this will be helpful.

Any help would be appreciated. Let me know if more information is necessary.


texts: microsoft robotics: cheap but very extensible robot?

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Is there any cheap and very extensible robot kit, which can work with Microsoft Robotics?

I want to have a great choice of cool parts for a robot to buy :)

If where is no such robot kit which can work with MS Robotics, is there any chance to buy a very extensible robot which just can be programmed, maybe even in assembler?


texts: What is harmful for electronic circuits? Voltage or electrical current?

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Its said that if you get more electric current, the electronic device in a circuit  will just take what it needs and its not dangerous, so if we raise the voltage and therefore the electric current increases but the device will take just the electric current it needs, where is the parameter I am missing to undertand why increasing  the voltage is dangerous for the device?

Thanks


texts: Combined ADC level shift/offset and scaling

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I'm trying to sense the voltage from a 2 cell Li-ion battery that has a usable range from 2.5  to 4.4 Volts per cell (nominal 3.0 - 4.2 V). The ADC I have has a range from 0 - 1.8 V and is 12 bits. I haven't been able to devise a solution that makes effective use of the ADCs range and scales the battery's voltage linearly. Ideally I would like to sense from 5 - 8.8 V volts rather than 0 - 8.8 V. I have a variety of resistors and an op-amp (LM324) available and have 12 V, 5 V and 3.3 V (and GND) rails available too.

So, what are some feasible solutions that will work well within the constraints?


texts: Relay Solution for Controlling Pumps with Arduino

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I'm working on a hydroponics project that requires me to run 10 pumps for 15 seconds every 2 minutes. I was able to set this system up by running a relay board off of an Arduino, but the relays were mechanical (and fairly cheap) and within 13 days they had started to break down. I've had to switch out the relays to get the pumps working again, but I'm almost out of relays to switch.
From my research, it looks like solid state relays might be the way to go. So, my question is: are there solid state relays that can handle 12VDC, 5A and reliably switch - on average - once a minute for extended periods of time? And if so, how can I control them using the Arduino board I already have (if I have to buy a shield or anything like that, that's fine). I currently have a power supply that can supply 12VDC and 10A max, so I'd like to continue using it; but if I have to buy a new power supply, I can do that too.

Thanks!


texts: Reverse NC output to NO for a card reader

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I'm fairly new to electronics and am stuck at how to get a circuit working. I have 3 components connected in the circuit:- a card reader, relay and an electronic door lock release, and all operates at 12v DC. The card reader is continually powered on and is a NC type, meaning when the reader has power an internal switch is always closed and it outputs a short to ground. When a registered card is presented the card reader's internal switch closes for a set time (approx. 15 secs) and the short to ground becomes an open circuit, and after the set time the internal switch returns to a NC position and the short to ground is restored.
The reason this card reader operates as a NC type is because it is primarily used for magnetic locks which are always energized to lock the door (hence a constant short to ground to power a component) and de-energized when the door is unlocked (short to ground becomes an open circuit and power removed from a component).
I will be using a conventional electronic lock release which requires the relay to be powered on only when the door is required to be unlocked and no power to the relay when the door is required to be locked (basically the opposite way a magnetic lock works). So when the door is required to be locked I need the relay to be powered off so the lock release (on the load of the relay) is not operating. When a registered card is presented to the card reader I need the relay to be powered on and in turn the load circuit will be complete and the door lock release will operate and unlock the door. After approx. 15 seconds the card reader will return back to the NC position and I need the power to the relay to be removed and hence the door lock release will not be operating and the door will be in the locked position again.
I have looked at NPN / PNP transistors but they require the output to be in the “on” position to operate the circuit, but my card reader had no output when I want the circuit to operate. I think I need a MOSFET transistor but can’t figure out how to make it work.
NOTE: I cannot do this with a relay with NC outputs, i.e when the relay isn’t powered to use the NC outputs of the relay to complete the load circuit because of fail safe. By using a NC relay if the card reader was to lose power, so will the relay and it will default to the NC position (as it won’t be powered on) and the door will open when it shouldn’t be.
Thanks in advance for any help.


texts:
I'm trying to understand how the following FM radio schematic works.

Specifically, I want to know how the carrier wave is generated.  I understand the concept of an LC tank and I think I see it there in the upper right, but what I don't understand is how the oscillation / resonance gets started.  All of the examples that I'm seeing online show the use of a frequency generator to make a LC tank "go".  Obviously there is no frequency generator attached to this small (simple) circuit.

I asked a friend and he told me he suspected that the transistor(s) were involved, which makes sense, but I'm hoping someone can either explain that to me in more detail or if it's too involved to answer here, point me at some resources (books, web sites, videos, etc.) to get me moving in the right direction.

Thanks!

Update
Many thanks for all of the great information.  After learning that this is a Colpitts Oscillator I was able to find the following resources that give even more details.  I'm posting here for my future reference and for those that might find this question useful:
Wikipedia
Learn About Electronics
YouTube Video
A breadboard based example
Falstad Circuit Simulator
Learn about electronics


texts:
I'm trying to design a bench power supply that can be easily controlled by a microcontroller and is more efficient than a simple linear design (although crazy-high efficiency is not the primary target). I've come up with the following circuit:

simulate this circuit – Schematic created using CircuitLab

I've purposefully removed all part values and names to only discuss the overall topology. Here is how I envision it to work:

\$V_{set}\$ and \$I_{set}\$ are two analog voltages that set the target voltage and the maximum current supplied to \$R_{load}\$.

OA2 will try to keep the voltage at its output such that the PWM value is sufficient to keep the voltage at \$R_{load}\$ to \$V_{set}\$.

OA1 will rise its output voltage whenever the current flowing through the load exceeds \$I_{set}\$, thus activating Q1 and lowering \$V_{set}\$ to a value such that the current is not exceeded.

Are there any glaring issues with this design? Does it only work in theory, but is useless in practice?

I have not yet decided how the PWM signal will be generated or what the range of Iset and Vset will be, but I thought I'd validate the design before worrying about the details.


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I am extremely new to this and I'm learning by building stuff myself so please let me know if this is too vague and I'll elaborate if I can. I'm sure this is something very simple, but can't figure out how to do it.

I have built radios before and know how to modulate a signal as ASK but now I'm trying to send a simple bitstream from a USB port to a radio's input. My idea was to use a serial program to dump bytes into the radio input signal but all the research I have done indicates using rs232 or UART or something. I have no experience with this and I don't want some protocol sticking parity bits in all over the place. I simply want to be able to send, for example, 0x1234 as 00000001000000100000001100000100 at a baudrate of \$2048\$. Can I go further and actually send individual bits like start/stop bits?

My intention is to monitor the frequency with an sdr and then learn how to demodulate the bits from the IQ data.

Is there a simple method outputting bytes directly onto the wire or something I don't know about which will prevent me?

Any help or direction would be greatly appreciated.


texts: Would the electrical circuitry of an immersion heater be affected if taken out of the water immediately after switching off?

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I have an immersion heater like this:

and the tiny instruction manual says

  "Please keep the heater in the water for a minute or two after
  switching off the current"

...but they haven't explained why. So why would this be required? The coil immersed into the water is a metal jacket which would have a wire passing through it which makes it a bit like a resistor, I assume. Whether it is taken out of the water immediately or after 2 minutes, it will have to cool down and the metals will contract in both situations, and I don't see how it would affect the circuitry and therefore the life of the appliance. Besides, leaving it for two minutes after switching off will allow the water to cool also, which defeats the whole purpose of heating the water.


texts:
I have many test points on a board, a small DAQ, and an SMU that I can program with LabView. Depending on the test, I need to change which test point the SMU is sending/measuring voltage or current.

To do this, I figured I should use a series of analog switches, and control the switch paths by using the DAQ's few outputs. (Eg. Outputting the high/low binary 000 sends the signal to the first test point TP1; 001 routes the SMU to TP2, etc.)

However, some of the tests I'm automating require sourcing/sinking up to 500mA of current from the SMU to the test point, and most switches advertise their "high-current capacity" of 150mA or so. Additionally, my SMU signal reaches a maximum of 20V at times, so it needs to be able to handle both.

I find it hard to believe that there isn't a switch that can do what I need, so what should I be searching for?

Is this usually how this kind of task is accomplished, or is there an alternative to switches that would be better?


texts: What is a suitable hysteresis value and averaging period for a residential thermostat?

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I've built a microcontroller based thermostat that I am using to control my home HVAC system. The actual programming and physical assembly has been straightforward. I'm using DS18B20 sensors, so I have far more precision available than I actually need. I take a sample once a second from the sensors.

What I'm trying to figure out is what the appropriate value for hysteresis and averaging period for temperature measurements are.  Hysteresis is pretty easy to implement. I have a value of 1.33 F presently, meaning I turn off the AC when the temperature reaches 1.33 F below my set temperature. I'm using an exponential weighted moving average for the temperature value. This is because I don't have much RAM available. I used the typical alpha = 2/(N+1) with N=360 for an approximately six minute averaging period.

The combination of the above two values seems to have produced a system that behaves acceptably. Initial experiments with N=60 for the exponential weighted moving average resulted in a system that cycled on and off very fast.

Are there any industry standards for implementing things like this? My goal is to avoid short cycling the system. I live in a net cooling climate if that matters. Also my system isn't terribly oversized. In the peak heat of the summer the system needs to run greater than an 85% duty cycle to keep the house cool.


texts:
I Recently disassembled two printers, and I found a lot of neat sensors that I'd like to use for my projects. I've tried to search around the web, but I can't seem to find any pin out or datasheet for this type of sensors. They are kinda similar to the photo interrupters, but these seems to have 6 terminals instead of four. Here's some pictures:

Also I may add that some of them come with five wires, but most of them have just four.

Hopefully someone here could help me out, a circuit diagram of some sort would be really helpful as well.

Thanks.

Update

I've powered the sensor as recommended, and I found that pin 3 is connected to the "photo interrupter"-part of the sensor. I measured about Vcc between pin 3 and GND when the IR-light was blocked, and about 0V otherwise.

I didn't find any variations for pin 2, it stays at Vcc. Any ideas? But I have yet to try the "motor-sensor".

simulate this circuit – Schematic created using CircuitLab


texts: MOSFET switching seeing unneccessary pulse during Power ON

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We have a MOSFET switching circuit to switch secondary(battery 5V) supply to load if power lost on primary(12V).

Circuit works fine currently.

But i am seeing a LOW pulse on highlighted red net in the attached capture ONLY during Power UP.

Input to MOSFET from CPLD is LOW.

Power net Vbat1(drain resister voltage) is rising smoothly.

this looks hypothetical to me. Because for a n-Channel MOSFET switch gate is 0V, still looks like MOSFET is ON for short time.

Is there any way pulse**(Low spike)** is generated on highlighted red net even though gate is @ 0V.

I will add few captures tomorrow.

One of the capture:

Zoomed up


texts:
Hi, I want to run a 24v motor with a 12v h-bridge mosfet driver (HIP4081A).
I haven't try it in real life but I made the schematic. I want to know before testing it if you can find any error or bad idea in my schematic.

I was successful to run the motor on 12v with the same battery than the driver.


texts: Turning a pulse into an extended on signal

texts:
I have a device which outputs pulses at 5V. I want to detect these pulses with my Raspberry Pi later. The problem is that my Raspberry Pi script will be doing other things that take time, and I'm worried that it will not be able to pick up on the pulses (it will not check the state of the GPIO pin when the pulses occur).

Is there some way to take 5V pulses and not only turn them into a solid logical on, but also extend the length? My dream would be that whenever the pulses happened, I could have a 3.3V signal be on for a minute or so.


texts: Have I got these simple power calculations right? (for battery consumption)

texts:
Lets say an ideal AA battery I have provides 2.0 Watt hours. It could be different, just a quick search for this example.

My very simple load is the battery connected to a 5mm LED. The LED has a forward voltage of 2 or so volts and ideal forward current is 20 mA for good lighting.

Here are my calculations:

Load (power) = 20mA * 1.2v(battery) = 0.024W (or 24mW)
Possible life: 2Wh/0.024 = ~83.3 hours = ~3.47 days

Is it correct to divide watt hours by watts used, to get hours again? I am a bit tired, although 3.5ish days sounds fairly correct - thought it would be more.


texts: In a circuit being switched by an NPN transistor, do power supply and input need the same ground?

texts:
I'm trying to make a circuit that will allow me to switch on a relay that will turn on an LED. However, the relay is rated for 12 V, and I only have an input of 5 V, so I'm using an NPN transistor. to switch the power to the relay on and off. Here's the schematic:

However, I'm confused about a few things (Note the ground for both the 12 V power supply and the 5 V power supply are unspecified):

If my 5 V power supply is an Arduino, can I use the ground for that for the ground of the 12 V power supply?
Is it okay for the base and the emitter to have different grounds on the transistor? Or do they have to be the same?
If my 12 V power supply is 8 AA batteries (not sustainable, but I'm just using it for testing), how would I connect that to the same ground as the arduino, instead of the negative side of the batteries?
How can I figure out what the R1 and R2 should be, based on the transistor? I read some things online, but am still confused.
Are there any other things that I'm not taking into account that I should be?

I'm completely new to this, so any help is much appreciated.


texts: What is the principle of operation of this power supply?

texts:
I bought this power supply off Amazon, it is described as 5 Volts DC 60 ampere. I was able to adjust the output so it produces 5 volts at its terminals.

Here is a link to where I purchaed it from:

https://www.amazon.com/gp/product/B017YEOAPA/ref=oh_aui_detailpage_o03_s01?ie=UTF8&psc=1

Internally it  consists of a power supply built around a TL494. The design seems typical, but I am unsure how it works. There appear to be two switching components labelled SPYM309. I can't figure out what these are. I expected them to be driven with some sort of signal 180 degrees out of phase with each other, but even using both probes I could not find such a thing.

The other unusual thing is the electrolytic capacitors on the output are rated for 25 volts. The larger components mounted to the case on the left hand side are just two pairs of rectifiers wired as a full bridge.

I know the TL494 internally is two error amplifiers and some other components. I probed around inside the power supply and eventually gave up on trying to figure out what was doing what. I could not even find the +5V from the internal reference regulator on the TL494. I added a single turn of 22 AWG magnet wire to the larger transformer and found this wild waveform. This is using a 2 ohm load. Note that I accidentally had the scope displaying 10x here, but the probe is actually set to 1x

The output waveform seems to just "wander" for about 65% of the time, but the other 50% is spent doing something square wave-ish.

The next test was the same thing, but with a 0.4 ohm load. The scope's setting was 1x, as well as the probes in this capture

The output waveform cleans up quite a bit with the larger load. Interestingly, it still spends about 1/2 of its time around 0 volts.

I have a couple questions about this power supply

What  does the smaller transformer do?
What are the two switching components?
Should I expect to find the two switching components in a push-pull configuration?

Any other suggestions on more interesting things to measure with my scope would be appreciated!


texts: Atmega ISP programming headers - muxing suggestions

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I'm currently working on a project that involves multiple Atmega devices. I'm planning to leave ISP headers on the board, but I don't want to leave 1 set of ISP headers for each chip (I'll have 4-5 of such chips). But instead, I'm thinking of cleverly placing jumpers and headers as to "select" the device being programmed. This way I get to use only 1 set of ISP headers.

My question is which ISP line can I select for muxing. ISP lines consist of the following

VDD
GND
SCK
MISO
MOSI
Reset

My guess would be if I disconnect SCK line for the 4 devices that I'm not programming, but connect this line user a jumper for the device that I am programming, then I end up with programming this 1 target device. Is this a feasible idea?


texts:
I have a pretty unusual application here, where I need to drive a fast differential signal fanning out into 8+ 100ohm transmission lines. The unusual part is this: the transmission lines must be perfectly synchronized. The exact same signal must be driven on all the lines. This rules out the usual PECL fanouts, since there is some skew on the outputs.

My plan is to take a PECL fanout buffer and parallel the outputs (i.e. short all the +Q outputs together, short all the -Q outputs together), then drive all the transmission lines from a single physical point. That would give the strong drive with a single waveform.

I have done this routinely with CMOS drivers, but this is my first time doing it with PECL. Are there any issues with this approach? For example, do I need to put some resistance in series with the PECL emitters?

I am using this chip: CDCLVP1216

Here's an idea of what I want to do:

simulate this circuit – Schematic created using CircuitLab


texts: Can someone tell me what this datasheet is trying to tell me?

texts:
This datasheet is for an audio delay IC that i plan on using:
http://www.ti.com/lit/ds/symlink/tpa5052.pdf

I understand everything pretty clearly except some important details that i've circled in this screen shot photo:

The blue circles i've made are supposed to be data as far as i know, but they seem to be deliberately stopping short of the left/right word change. Why? I've read this entire datasheet over and over and can't figure out why they stop short.

Also (yellow circles) it's trying to use left and right arrows and a full clock pulse to tell me something... again with no info regarding it. Please help!


texts: AC/DC power supply: help to choose fuse, varistor and/or TVS diode

texts:
I'm going to use this 12VDC AC/DC power supply . It is the first time that I am going to use one and I have some questions about over voltage protection and peak current protection. These are the questions:

The AC / DC internally has a 1A slow blow fuse. Is it necessary to add an external fuse? Maybe something less than 1A to protect the internal fuse?
Regarding the input overvoltage protection, I have thought to use a varactor. The problem is that I do not know to find the information in the datasheet about the maximum input AC voltage. What characteristics should the varactor have: max. continuous voltage, max. clamping voltage and energy rating? I have found this good explanation (How to choose the right Metal Oxide Varistor (MOV)) but I still do not know how to choose the varactor because I can not find all the information in the AC / DC converter datasheet.
About the output overvoltage protection, I have read this parameter in the datasheet: 'Over Voltage Protection (OVP)' -> '125% - 195%, auto recovery'. I do not understand this parameter well. Should I add a TVS diode to guarantee never to exceed 195% of 12VDC?

Below is a circuit diagram to clarify:

simulate this circuit – Schematic created using CircuitLab

Thanks.


texts:
I have a linear range control signal from 1.75 V (0%)  to  3.22 V (100%) .

How can I convert this to a 0-5V signal (0-100%)?

I have a single +5V supply with same 0V as control signal.


texts:
Alright, I'm totally confused. I have built the following circuit with absolutely no result, not even a click. Even after reading through several other similar questions on the board, I haven't debugged it.

I am using about 15 feet of wire for an antenna and the metal case of a circuit breaker for ground. I've tried using a 100uH coil from radio shack and a 15uH choke for the inductor. I've tried a variety of capacitors as well as an air variable 1.4 - 9.7 pF capacitor. From the LC calculators I've checked out I should have been able to get AM stations with the varicap/15uH choke combination. I have a glass type "switching" diode but I'm not absolutely sure it's germanium. I've used two different piezoelectric ceramic disks in place of the headphones. Right now I'm suspecting the piezo disks. Are they not high enough impedance for this to work? Or is one of my other parts incorrect? Thanks in advance!


texts: What happens when transistor operates in saturation region for constant current source

texts:
I am learning about the constant current sources and I found this video

What I dont understand is that, when the forward voltage of the LED is increased from 1.7V to 3.3V, and our Emitter voltage is maintained at 2V, the voltage across the Collector Emitter Junction is decreased. This makes the transistor to work in the saturation region.

Why does the transistor in saturation region does not help in providing the constant current. In all the cases mentioned in the screenshot, Ie=Ve/R which is always 2V/100ohms, 20mA. Since, in all cases (different LED Forward voltage and same Vdd supply voltage), we are getting the same load current. So, what's wrong with the transistor operating in saturation region in this case?

Please clarify if I am wrong


texts: Any good method for the power down sequence?

texts:
In my circuit, +12V would be supplied by an external power source. After two regulators, two more voltage sources (+5V and +3.3V) would be produced and supply power to the AD7682 ADC. Because of the maximum rating limit of ad7682, 3.3V needs to be down before 5V when I shut down the external power source +12V. Is there a good method to achieve this?

(I learned that some sequencer ICs can monitor the power sequence process. However, when I shut down the power source +12V, no power can be supplied to the sequencer ICs. So I think ICs are not suitable in my case.)

simulate this circuit – Schematic created using CircuitLab


texts: Slowing Down a 12 volt pump with a potentiometer?

texts:
I have a small pump hooked up to a 12 volt battery. But as is, it is working too fast and I would like to slow it down. The pump draws 300mA (though it's start up inrush is 3x that).

I am a little confused as to what kind of potentiometer I should get. If my rudimentary skills are correct, at 12 volts  I need a minimum of a 40\$\Omega\$ potentiometer capable of handling 3.6 watts (not including the inrush).

But most of the potentiometers I am finding are only rated for 1/2 a watt, and many are ratted for 1,000+\$\Omega\$...... so can anyone recommend a good potentiometer for my needs?


texts: Is a PWM required for regenerative braking on a DC Motor?

texts:
The DC Motor is question is here: DC Motor

I was wondering if you use a diode and a switch in a manner shown in the below picture if the motor would exhibit regenerative braking when SW1 is open? (Assuming that the voltage from the motor when braking exceeds the motor power) Is the use of PWM required?

simulate this circuit – Schematic created using CircuitLab


texts:
I mostly use Orcad Lite to browse schematics, doing a lot of component/net search.

How can I search using Tcl console?


texts: Is it mandatory to use thermals in hand soldered PCBs?

texts:
I understand thermals are used to prevent tombstoning during oven soldering by allowing all pads to heat up more evenly, but are they necessary when the PCB is going to be soldered by hand?

Consider that I have experience soldering SMDs and that I have a good soldering station(as in one that has no problem soldering heavy packages and heavy wire).

Also, the PCB will have solder mask so solder won't just run around, etc..

I ask this because I'm designing a 2 layer PCB which is quite dense in some places and disabling thermals allows me to leave more copper on the power pours in dense areas..

Below image without(left) and with thermals(right).


texts: Component libraries for schematic and layout design

texts:
I've got much difficulties to find the footprint for the components I have in hand:

They don't have name (I buy them at somewhere similar to flea markets). Therefore, their proper footprints are unknown nor I don't know where to find such information. So far, I've been wondering if every component (such as resistor, cap, connector, header..) they all have standard footprints? where to find such information?

For the libraries available in CAD tools like eagle, proteus, orcad, they don't have the visualization (photo...) of the component so that I can guarantee the chosen footprint is suitable with the real one

For such reasons, I would like to know if there is an online or offline component library and browser which has:

1 photos of each component. This is meaningful since it may help to quickly verify if this component is the one the designer is having at hand or visually remember
corresponding schematic
corresponding footprint with some brief descriptions about pad size, distance between pads. This supports specific measurement information for the given photo

I am still at learning level in electronic design and have found EE SE is a great learning resource. Please pardon me if my questions does not make sense. In that case, your response would also help me to justify my understanding.


texts: Where exactly earth current flows-SMPS/DC-DC and DC-AC

texts:
Ashamed to ask this question after having lot of experience in Converter designs. i always heard and learnt from Sr. Mentors that For better EMI performance we need to give path for conducted noise(and leakage currents) to flow, in this case its Earth ground (P.E). and yes i take care of this in my designs. But never though or understood where exactly this noise will flow. Will it flow into magical Earth? or will it go back to distribution center.
I see people sticking copper rod into earth (with salt and coal etc) and call it earth and connect protective earth (P.E) from their home to this copper ROD. Will earth accepts any electrons pushed to it? doesnt makes sense. where exactly all this H.F conducted noise go (or leakage currents)

::--- Please dont take me as rude but do not reply if you are just learner or one who didnt understood it well , just to avoid multiple false response which could confuse new learners. i am expecting answer from some one who is expert in this field by his profession or studies--:


texts: Why does only the fermi level shift in a semiconductor under an external electric field?

texts: I find a difficult time understanding why does  only the fermi level shifts in a pn junction under an external electric field? Why are the conduction and valence bands not affected by it?


texts: ESP32 logic HIGH/LOW level voltage, not working?

texts:
From ESP32 datasheet:

In my case:
VDD = 3.3V

Vil (max) = 0.25 * 3.3 = 0.825V
Vih (min) = 0.75 * 3.3 = 2.475V

Theoretically:

LOW LEVEL range is -0.3V to 0.825V
HIGH LEVEL range is 2.475V to 3.6V

But when I tested practically:

LOW LEVEL range is 0V to 1.67V
HIGH LEVEL range is 1.67V to 3.3V

Question : Why is my practical range far different from the theoretical range and what does theoretical range from 0.825V to 2.475V mean?


texts: How to determine current direction against a parallel current source? basic question

texts:
If you look at the node-voltage equations, you see that current of 2ohm-resistor is towards v2 node. How is that determined? If I change the direction the ends of the voltage on that resistor and make the current go the other way, only the third components of two equations change sign and that makes another value arise for i1. So I think it does not depend on my choice and has a special way to determine.

Thanks in advance.


texts: How are instrumentation amplifiers constructed on the semiconductor level?

texts:
I'm curious as to exactly how in-amps are designed at a transistor level. They're often shown as being made of three op amps, but due to how specifically the amplifiers are being used I expect that there may be some differences between them, to optimize performance for certain things, and some things (the reference side of current mirrors, perhaps) might be shared between them.

I strongly doubt that they just copy the same op amp design three times and add resistors.

So, to sum it up into a question: How are instrumentation amplifiers designed, at a transistor level? How are the three component amplifiers specialized for their limited tasks, and what, if any, circuitry is shared between them?


texts: What will it happened when capacitance is almost the same as parasitic capacitance

texts:
I make a sample and hold (IC design),and it is combined with transmission gate and a 550fF capacitor,and my classmate told me that my capacitor is too small,almost the same as the parasitic capacitance,and also told me it may have some problem when post-sim.So i want to ask:

What will it happened when the capacitance is almost the same as parasitic capacitance when doing post-sim ? Because it is design to on-chip,so the value of it cannot be too large.


texts: Spliced LED Strips with Pre-Fab Controller

texts:
I need 2 meters of high density LED strip for a project, but high density strips are often only sold in 1 meter increments.

I'm thinking of buying two strips -- of one meter each -- and soldering them together on their contacts end-to-end.

But I'm wondering if that would create any confusion in the pre-fab controller (the RF Magic Controller). Specifically, the controller has a lot of predefined color patterns that start by illuminating LEDs on each end of a strip and meeting in middle...would my spliced frankenstein strip be accurately recognized by the controller as one long strip of 2 meters, or inaccurately as two strips of one meter (or worse)?

Thanks.


texts: How to solve a LED-resistor parallel with a resistor?

texts:
Hi there I am curious as to how you would solve this circuit to know voltage drops and currents. It came about from a previous question I had asked which showed my understanding was not quite what I thought it was.

I have looked at other questions of the exact same circuit but again I could not find an answer for myself. I will reference the sources I have found in the bottom. reference 2 seemed to answer my question but I don't understand how to solve the equation, reference 3 had a great explanation but subsequently didn't answer anything for me and reference 1 (and other sources) implied to view it as a voltage divider which would make sense looking at the circuit but when doing my own simulations it didn't seem to add up.

A lot of people talk about using 'thevenin' but I have never came across this before in all my online videos/guides/tutorials/textbooks/highschool physics classes. I am still a beginner and am trying to self teach so maybe I am just not at that level yet.

The LED is a red 2v.

simulate this circuit – Schematic created using CircuitLab

From reference 2 the circuit is the same with different values.'Eugene Sh' from that question states I would find the currents by having the voltage at the node after R1 as V1. Then finding the currents as

I1=(5−V1)/50
I2=V1/210
I3=(V1−2vLED)/200

Leaving: I1=I2+I3: (5−V1)/210 = V1/210+(V1−0.6)/200 and they solved it for a V1= X.

My First Question: Is that how you would solve every equation like this? And  just use algebra to rearrange that sequence to make it: V1 = XXXXX? If so I dont know how to do that. as I get stuck moving the 2 divisions across. But if that is the way, I can look up algebra lessons or if someone wouldn't mind trying to show me how that would be appreciated.

Otherwise...

Reference 1 stated to look at it as a voltage divider

V1= Vin x (R3/R1+R3)  Which for my circuit: `V1 = 5 x (21 ÷ (50÷210)) = 0.403V

But that seems way too low (unless I made a mistake). as i think my simulation says it should be 3.68V With a drop of 1.32V across R1.

My Second Question: Do you use this situation as a voltage divider? and if so what did I do wrong.

My Simulation:

My Third QuestionDoes it matter if R1 is before or after the ResistorLED-Resistor section? As I thought the total resistance would be the same regardless of R1's position before/after.

EXTRA THOUGHTS

My initial understanding was to drop the supply voltage by the LED's forward voltage and use ohms law. However From my previous question asked I learnt that both resistors ARE NOT in parallel. Therefore it is confusing for me with my understanding as I thought that the voltage would split at the node. But now I don't understand how to find the total current with the split not acting as parallel resistors. Originally R1 was after the split creating a 5v divide across each lane. But I changed it to have it uniform with my references. I understand All voltage in must equal negative voltage out. and that current prefers the least resistive path.

I was getting help on my old question but I thought it is more appropriate to create a new question. please let me know if I am posting questions incorrectly as I am still new here.

Thank you for everyone's time.

REFERENCES:
Reference 1
Reference 2
Reference 3


texts: 24V LED strips connected in parallel - How should the data line be connected?

texts:
i have read around and finally understood how led strips should be run in parallel for my staircase project. However, i have 1 last question that needed an answer.

Please refer to the 1st attached diagram.

According to the diagram, the PSU handles each strip's wattage load separately and the controller does not have to withstand the total wattage load of all the 28m of led strips (400w+).

However, i have a question. How should the data line be connected in this case? Please refer to the 2nd attached picture.

It's similar to the led strip that i use except that the one i use is 24V instead of 5V.

I will be connecting the power supply to the extra red + black wire via DC connector.

As for the data line, it will be connected via JST connector. Here's the problem though - it seems to supply power as well through the red wire.

So for the data line, do i remove the red wire and connect only two wires (green & black) from the controller to the led strips?

Because if not, to my limited understanding, wouldn't it mean that the controller and the 4th PSU powering the controller have to sufficiently rated to handle the total wattage of the full 28m of led strips since they are all connected?

Thank you in advance :).


texts: Primary cell chemistry with the highest volumetric power density

texts:
I am working on a project (a disposible device) which requires significant power delivery from a small volume. This power delivery is very bursty, we're talking a handful of big pulses over the service life of the device. This is all super up in the air right now, but I am looking at around 0.35 mL of volume for the battery and I need to pump around 150 mW into a resistive load for a burst on the order of ten seconds (in order to heat something up). Primary cells are preferred for shelf life but secondary cells which can hold substantial charge for 2-3 years would be acceptable.

In order to bound the problem, I'd like to figure out what primary cell chemistry has the best volumetric power (not energy) density. Mass is not a concern. This would at least let me know what's physically possible, even if it's not neccessarily available off-the-shelf as a finished cell that fits exactly in my volume available.

I have started by taking a look at the comparison of commercial battery types article on Wikipedia. By dividing the volumetric energy density by the mass energy density of the battery, I can get the battery's density. From there, I can calculate the volumetric power density by multiplying by the specific power.

Unfortunately, Wikipedia's table isn't very complete, and is missing the specific power for a bunch of primary cell chemistries.

So, my question is: does anyone know what commercially-available primary cell chemistry has the highest volumetric power density? I am not adverse to paying NRE for a custom cell shape, but I need a battery chemistry which is used commercially, not something that's currently just a university research project.

PS: It also probably goes without saying, but molten-salt batteries, while technically a commercially available primary cell, are not practical for my application.


texts:
I have an Xmega Xplained 128A1 kit along with an AVR Dragon.

Can anyone help me with the steps to be followed for programming Xmega using Dragon using Atmel Studio 6?

I have downloaded the material from the Atmel website and have the necessary codes and other stuff. Unfortunately, the manual shows the steps with Studio 5.

The steps which I took:

Created the project in Atmel Studio.
Added the include files to the project folder.
Built the project. Build was successful.
Then compiled it. Compilation was also successful.

Now what to do next. I tried debugging, but it was taking too long and thus cancelled it.


texts: How will electromotor intended for 460V be affected by working on an installation on 440V?

texts:
How will an electromotor 150HP, 2-pole, intended for 460V, 60Hz, 3510 RPM, 197 AMP be affected by working on an installation where 440V/60Hz is the voltage?

With regards to number of revolutions and torque, and power in the end?

Can you estimate what will be the reduce in power due to difference in voltage?


texts: How to find popular and conventional electronic parts?

texts:
We have linear regulator: AMS1117 that I think it must be popular, since many company manufacturing this. Also some have changed it's name slightly to emphasis on their company like LM1117 and LT1117. I think a part has been populated, then many company has manufactured it to with that name and can be placed by previous one without any big stress. Is there some place that has been listed them? or this phenomena happening synonymous, only experience and encountering them in work will lead us to identify them?

Also is there any popular and standard RF component list (mixer, modulator, attenuator, lna ...)?


texts: Blocking stray RF with diamagnetic materials?

texts:
In my ham shack there is a wire that runs for 4 feet from my transmitter to
the RF ground and I wish to stop it from radiating as much as possible.
All of the normal precautions are in place but I enjoy going over the top with this kind of thing.  I am curious if a diamagnetic material could be used to block stray RF. For instance, running the ground wire through a tube of Pyrolytic carbon or Bismuth or another diamagnetic substance.


texts:
With PMOS and NMOS, one can deduce that it is off, if

Vgs < Vt (NMOS) || Vsg < Vt (PMOS)
id = 0.

Now my question rests on the dependency of these conditions.
I know proving condition 1 automatically implies condition 2. But can the same be said for the reverse?

Going off of this, in CMOS logic, does the current not matter in determining whether the mosfet is on or off? Clarifying the conditions of CMOS logic and how it is different from just PMOS/NMOS logic would be really helpful.


texts: Computer SMPS is working with high electric shock spreading

texts:
Sir,

I have a ATX SMPS, today its working and connected LCD monitor will be blinked anonymously, i touch the cabinet I get a electric shock from the cabinet, also CPU working and Its have high electric shock. Now I removed SMPS from the cabinet.. What is this  problem sir.


texts:
I have a problem working on Lab 3-5 from Horowitz's Students Manual for The Art of Electronics. The circuit is like that:

The author suggests compare the RC time constant of two version of this circuit: the original one and with 2.2K resitor removed.
The problem (for my understanding) comes when removing the resistor: the RC becomes about 100 times (or even more) bigger. To see what happens with initial differentiator (capacitor and 1K resistor) I've removed the diode also and the RC was as expected.
Supposing that something could we wrong with my diode I've tested is with a multimeter and the diode was correct.
So, I can't understand why rectifying the differentiator output changes so drastically the RC constant.

I'm very grateful if somebody could help.
Thanks

Here's what I'm doing:

Should it behave like this when adding a diode and why?
Then adding a 2.2K resistor between the diode output and the ground (i.e. the original lab's circuit) fixes the problem (which also I don't understand)


texts: Will copper wire with a non-tarnishing coating be insulated?

texts:
I need to make a coil to test voltage created by flux for a project, but bought the wrong grade of wire. Will the non-tarnishing coating act as a good enough insulator for voltages in the millivolts?

TIA


texts: when do we need to apply high speed PCB rules ?

texts: i'm new to pcb design and i'm wondering that starting from which frequency range we need to apply the high speed PCB design rules and techniques ?


texts:
I am working with the CS42436 codec, and in their datasheet, they have recommended values for components to be used in an active filter that takes the differential outputs from the DACs and converts them to a single-ended channel.

I have no problem with the values and what components to use, although I am concerned about the power going through the resistors and such.  Right now, I am using the recommended design using 0402 resistors and capacitors.  Apart from the assembly, will this size be okay for an active filter or do I need bigger components that can handle higher power?


texts: 12V AC to 12V DC converter to power an Arduino and some WS2812B 5050 LEDs

texts:
I am looking to convert 12V AC to 12V DC to power an Arduino through the VIN pin. The Arduino will be mounted on a PCB through header pins, please see below.
This is the board I have at the moment.
I am looking to add 2 inputs for AC-12V that is then converted to 12V DC which then in connected to the VIN pin of the Arduino.

The issue I'm having is that I can't find any chips that convert 12VAC to 12DC, the only ones I can find are 80-110 AC to DC.
Is it possible to convert 12V AC to 12V DC safely and could you please advise on the best way to do so?
Would this work as with an GBJ1504 and an 7805


texts: BPSK and QPSK's BER( In the case of coherent carrier)

texts: In BPSK signal coherent demodulation, if the recovered coherent carrier has a static phase error of 10 degrees, how many DB does the BER performance of the system decrease? The degradation of BER performance of QPSK demodulation system using coherent carrier with 10 degrees static phase error is analyzed?


texts:
I would like to define a C variable in RAM which can survive a CPU reset in NIOS II IDE. Something like __persistent in PIC world or __no_init in Renesas world.

Is there a similar keyword for NIOS compiler, which is based on gcc?


texts:
Placing ground vias all over the PCB (stiching) to improve the EMI.

Have all ground vias to be spaced the same distance? Or may they be separated different distances if it is under lambda/8?

I mean, I have to place ground vias all over the PCB edge to reduce EMI. The space between these ground vias are below lambda/20, around the edge. But the doubt comes from the ground vias which are not at the edge.

Have these ground vias to maintain the same distance between them? How can I calculate the maximum number of them?
Is there any rule of thumb to do it manually?


texts: How do the pins of this analogue switch correspond in this diagram?

texts:
Regarding an answer of my previous question, I want to use the following topology:

When the input is below the threshold, the comparator output is HIGH and the Analogue switch above outputs the set voltage. However if the input exceeds the threshold, the switch will output the input ect.

If I use this analog switch DG417(which I never tried before), does anybody know which pin corresponds what here?

Considering the above diagram for the switch, what does 0, 1 and X on the analog switch above correspond in the datasheet D, S1, IN, VL, S2?


texts: Fast charging 2.0: 7V×2.5A, 9V×2A or 12V×1.5A?

texts:
The FastCharge 2.0 standard has these charging specifications in the exact same charger (a VoltCraft car charger):

5 V up to 2.0 A  (10 W max.)
7 V up to 2.5 A  (17.5 W max.)
9 V up to 2.0 A  (18 W max.)
12 V up to 1.5 A  (18 W max.)

So the 7 V, 9 V and 12 V modes deliver pretty much the same power. The phone automatically adjusts to the supplied voltage. Some smartphones such as UlePhone Armor2 support 9V2A and 12V×1.5A.

For cables with higher resistance (i.e. long cables), the phone can 'request an increase of power' from the charger to compensate for the increased cable losses. So it's, "I want 1.66A, please increase the voltage until 1.66A is reached, I will deal with resistance control".

My question is:

When is utilizing 7 V × 2.5 A, when 9 V × 2 A and when 12 V × 1.5 A more suitable? The latter two deliver the same Wattage.


texts:
I have some experience using automotive relays and triggering them using the output from a two-way radio aux pin so I am aware of the need to add a diode in parallel with the coil to protect the radio's internal transitor when it is turned off.

However, I'm planning on doing a xmas project using a PIC MCU to turn on/off my xmas lights but I'm going to use solid state relays instead of the automotive type.

I haven't used SS relays before.  From a quick look at some schematics from Google, it appears that the control signal wouldn't suffer from the same EMF that needs a flyback diode.  Am I correct or do I still need one to save my PIC from destruction?

Thanks for your help.


texts: LM1117-3,3 keeps using more and more current

texts:
In the process of fault finding a circuit I am building using an ESP8266, I think I found the problem may be with my LM1117-3,3.

The circuit starts off fine drawing between 80 (off state) and 160 (on state) mA. I measure this via 10 10ohm resistors in parallel. I.E. through a 1ohm shunt resistor.

The strange thing is that the current keeps rising until the LM1117-3,3 goes into shutdown mode (Thermal I think). I tested the LM1117-3,3 through 1K1ohm resistor (Static resistor) and it starts off at the calculated 3mA but just keeps climbing.

The output voltage remains stable to the end, so no idea where all the extra current is going.

I have a 10uF cap between input and GND and a 100uF cap between output and gnd just like it states in the datasheet. Input voltage is 5.12V via a 2A capable plug pack.

Is this a faulty regulator?

Update
Circuit diagram tested above.

simulate this circuit – Schematic created using CircuitLab


texts:
I recently started electronics as my hobby. I'm working on this v/oct modular synth and in the schematic that I was working on, it did not make sence to me when all the Vcc and Vee are connected to the "GND". In my understanding, Vcc is the positive one and Vee is negative, and should not be mixed with others such as GND.

All of the Vcc, Vee, and GND has to be on a different connection right?

Where would I ground to, if I'd say that I wan't to look at the shape of the wave, using an oscilloscope?


texts:
I'm working on a pcb design on eagle, which will be used to test some sensors. The  design is made for three different sensors.

You connecet the sensor to the pcb, do the test and disconnect.

Here's one of them:

All three sensors have different connectors, two of them use female headers, therefore i was able to find male headers the size i need. The other one uses lug fork terminals.

I need to connect the lug terminals to the pcb to be able to test the sensor. My question is; How could i do this? could i use a header? if so what type?

Thanks!!


texts: Programming ESP32 Microcontroller with FTDI's FT231XS USB Chip

texts: Purchased FTDI's FT231XS from DigiKey I can see data from the ESP32 microcontroller but when I try to write to it, esptool just says connecting and nothing happens. I can use a usb to serial cable to write so I know the microcontroller is entering programming mode. I have verified continuity on ESP_EN and PROG pins. Not sure if this is a DTS/RTS issue or something else. Any help would be appreciated, I have attached schematic and layout.


texts:
This is a follow on question to a previous post about enhancing inductive spikes as I couldn't add images to a comment.
So I have revised my approach somewhat in that instead of using back EMF pulses to feed to an electrolyser, I have put together a circuit to generate HV pulses using a suggestion from this forum of a flyback transformer, which seems a suitable device for the task.
To this end, I have drawn out a circuit idea in Keynote and attach it. I usually start this way before creating a 'proper' schematic as might be a forerunner to a PCB.
My question is will this work and are there any modifications or corrections to the circuit, such as for more appropriate components?
The other pic is the intended waveform across the power transistor and hence the primary of the flyback transformer. Again my load will be an electrolysis cell with distilled water as the dielectric.
Thank you


texts: You can see some values on all electronic devices like 5V,0.2/0.3A on mobile chargers.What do these values represent?what can we understand from them


texts: What is the frequency response of a charge mode amplifier?

texts:
I'm having some difficulty understanding the frequency response of a charge mode amplifier, circuit shown in Figure 1 below.

                        Figure 1: Ideal charge mode amplifier circuit (1)

I believe I understand the principles behind an charge mode amplifier circuit, however I'm rather confused about the frequency response. Considering Figure 1 above, my understanding is that R1 and Cf will act as a low pass filter, where frequencies above a specific cutoff frequency (related to values of R1 and Cf) will be attenuated.
However, having had a read through a Texas Instruments (TI) PDF (2) discussing this type of circuit, the frequency response doesn't appear to follow this rule (I was expecting a low pass filter response). The circuit and frequency response described by TI is shown in Figure 2 below.

            Figure 2: Practical charge mode amplifier and frequency response (2)

I'd really appreciate if someone could help me understand this.

References

(1): https://commons.wikimedia.org/w/index.php?curid=16867828

(2): https://www.ti.com/lit/an/sloa033a/sloa033a.pdf


texts: Impedance Matching With L-Network, Terminology Issues

texts:
Note: Using L Networks

I am having some confusion with the terminology of impedance matching. Specifically majority of questions i have done state match a load to the source impedance which i interpret as the load must be essentially the source impedance after the other components are found (i.e. the cap and inductor etc).

However i have come across a question which stated to match the output impedance of a signal source to a resistive load at a specified frequency f0 for maximum power transfer. I am confused for some reason by this wording. Does it mean that the source must be matched to the load instead so the source should be seen as the load after the other components are calculated? Or can i just do it like the other questions by matching the load to the source?

As for the example 1 below if we are matching the source (50 ohm) to the load (500ohm), does this mean for calculations zin would be the load or not?

Or is this the same as just doing it the normal way by matching the load to the source. i.e.:

If it is the same why is it the same? Thanks in Advance


texts: Why does a virtual ground form for differential pair?

texts: In the schematic above for MOS differential pair, why does virtual ground form? The book says because of symmetry, but I don't really understand it.


texts: How to count the number of people in a room with a specific sensor?

texts:
I want to count the number of people in a small room. According to my research, there are person-counters in the web but I want to use the number of people data for coding hence I must transfer the number so I found occurence sensors can be useful for this goal. However, I cannot trust these sensors much.

So is there any practical way to count the number of people in a single room at any time ? What should be my steps to calculate this ?

Thanks...


texts: Supply interchanges between AA batteries in series and solar panel

texts:
I want to supply my product that has a sleep consumption of 40uA and an elevated consumption of 200mA during standard use.
I want to use the solar panel to supply the 40uA during the sleeping time and the batteries (6,3V-3,9V) to supply the standard use. The maximum supply voltage of my product is 9V and the cut-off is at 3.9V.
I want to know which the best way to interchange these sources.
I thought of using a solar panel of an elevated voltage, 7V for example, and separate the two sources via diodes. In this way, when sleeping, the solar panel would supply due to it have a more elevated voltage, but when the consumption increases, the batteries will supply.

What kind of diodes I should use?
Is there another method which would be more efficient?


texts: How does a non-designer understand a chipset's functionality?

texts:
I once met a person who told me as a part of his work he was testing and characterizing analog chips which include all sorts of components like ADCs, DACs, regulators ect. embedded in one chip. But he said he doesn't know how to design such a chip not at all about VLSI design.

How come such complex transistor level circuit functionality is understood by a person who wants to test it? Do they provide extra diagrams? And lets say if one wants to check only the ADC components how is that possible in such a complex system?


texts: Why are cables rated for current not power?

texts: I was wondering, since resistors are rated for power, not current (so one can blow them with both overcurrent or overvoltage), then why are cables rated only for current? Aren't resistors just stacked up wires? The question could be also asked in reverse- why are resistors rated for power, not current only?


texts: Can you measure the voltage of a capacitor with using an oscilloscope without a function generator?

texts:
Can I just use my oscilloscope to measure the voltage across a capacitor or will I need a function generator for that?
For some reason it shows what looks to be like a capacitor charging if I am not mistaken.
Here is the picture of the circuit:

Picture of the simulation:

Trying to reproduce the results I get this:


texts: Can't get a small 3 phase generator to produce 1/10 of its rated output. I need a little help.

texts:
My concern I am writing about is with a small generator not producing current or being able to be loaded. First I'll describe the product. I bought a couple mini brushless 3-phase generators (motors). They have a delta wire outlay I assume since they only have 3 wires coming out. They are rated at an Output voltage of : 3V-24V; Output current of : 0.1A-1A; Rated speed of : 300-6000 rev/min; and Rated power : 0.5-12W. The 3 phase motor consists of 9 coils and 12 magnets on the outside.   Here is a link to the product.

I wanted DC so I built a 6 diode bridge rectifier to turn the ac into dc, I even bought schottky diodes which supposedly have lower forward voltage. Currently with my drill I can only spin the thing to 900rpm. I know that's on the low end, but out of the diode rectifier I still read 10 volts dc. So I have a working voltage. The problem arrives with the amperage. I could barely get a 5 watt bulb to barely start to turn on to a faint orange glow. Now I have tried generating with a brushed dynamo, if I dont spin it fast enough I don't get the voltage. But! form 0rpms and 0 volts I can feel the load when I try to turn it and it resists.

With this small brushless generators, I was not sure if the load was too small to feel so I over loaded one of them with a 30 watt bulb. I then tried turning the generator with my fingers to see if I could detect a small resistance (given that the generator and rated output is small) but I feel no "load" on the generator, then I proceeded to spin the thing at 900 rpm's with the drill and the voltage with the load connected would not surpass .2 volts and 0.02 amps. I never encountered this type of problem with a small dynamo.

So I can't tell if I don't understand how to work with a 3 phase motor. I know my diode bridge is connected correctly. yet I can't get the little thing to turn on a small 5w bulb, or even to burn the windings by over loading it. not a touch of heat. I know my connections are good because i read the voltage throughout the system. Would anyone have a clue as to why I might not be able to "load" my small generator? I tried 2 of them so its not a faulty singular unit. Any advice would be appreciated, and I apologize for how confusing the whole thing seems, I am trying to make sense of it the best i can myself.


texts: Two pin PWM signal to control solenoid/electromagnet

texts:
I am building a whiteboard CNC pen plotter for my classroom out of some old 3D printer parts, a Melzi board running Ramps 0.92 and Inkscape to generate the Gcode. I have the machine up and running but I need a solution to actuate the pen in and out. I want to use an electromagnet or solenoid to do this and I was thinking of running the solenoid off of the cooling fan header. I can use Gcode to turn the fan circuit off and on or control its speed via PWM. The system is a 12 volt system and I think the old 40mm fan was rated at 0.18 amps, 2 pin. I am wondering if a small solenoid could be powered by the fan circuit? If so, what ratings should I look for? Would a solenoid be a bad choice? Could I buy some magnet wire and wind my own electromagnet which could just pull the marker into the whiteboard? I don't need much movement out of the pen, just a few mm.
I know there are better solutions out there like using a servo or another stepper motor. I am avoiding the stepper motor because I am trying to keep the mass of the moving parts as low as possible. I would use a servo, but I really don't know a whole more than basic circuits. Is there an easy/cheap way to convert the two pin pwm fan signal to a servo signal?


texts: 3dB Frequency of non-inverting amplifier

texts:
The question is

The op-amp is described to have that transfer function and I am supposed to find the 3dB frequency of the entire amplifier. Here is what I did

I used the fact that 3dB frequency occurs at a gain reduced by a factor of 1/sqrt(2). I'm getting a wrong answer.


texts: What type of screw driver do I need for this type of small socket 5 sided star screw?

texts:
I'm trying to open up an electronic device with the following 5 sided star screw nut. I need a precision 5 sided socket screw driver and I cant seem to find the correct one. How would one find the correct tool for these type of screws when we never have encountered them before? Is there a scientific method of calling these screws so we can find the correct tool easily?

(ex. Pentagon Star nut screw?)


texts: Constant Voltage model pf Diode circuit analysis

texts:
I have solved this problem assuming an ideal diode model, but now I'm required to use the \$0.7\$V constant voltage model. If the same circuit in ideal model had both \$D_1\$, \$D_2\$ conducting, does that mean in constant voltage model \$D_1\$ and \$D_2\$ will conduct?

I solved for \$D_1\$ first, assumed that it's OFF, and then calculated the voltage difference between anode and cathode. That gave me \$0.733\$V so I assume it's supposed to be ON (conducting).

Solution here:


texts:
I have a few circuits here that work with 42v to 5v/3.3v regulation. To achieve that there is a switching regulator with a linear one in series. Is that really needed?

I know the switching ones may have output noise but can't that be solved with a few passive components right after the regulator ?


texts: What the maximum possible temperature that a MOSFET can reach?

texts:
I'm choosing a switch for a power supply design. I would like to know the highest temperature the MOSFET can reach. The switch that I'm using is DMT3020LDV.
An input having 24V and 8A is supplied to the drain of the switch. The following are my calculations for the junction temperature:

\$T_j = T_a + (P_t \times R_{ja})\$

Where:

\$T_j\$ = Junction Temperature;
\$T_a\$ = Ambient Temberature;
\$P_t\$ = Total Power dissipation = 0.9 W (from datasheet);
\$R_{ja}\$ = Thermal Resistance, junction to ambient = 138 °C/W (from datasheet)

So, \$T_j\$ = 25(room temperature) + (0.9 x 138) = 150°C.

But if the outside temperature is 85 °C, will \$T_j\$ = 85 + (0.9 x 138) = 210°C?

Are my calculations correct? Because 210°C is too high in my opinion.


texts:
I need help in solving the below question.
Bandwidth of the signal is 1KHz. Use a 12-bit ADC with SNR of 78dB for sampling. the sampling frequency is 12KHz. Choose suitable filter order and cut-off frequency


texts: 555 high amperage charge pump inductorless voltage doubler

texts:
There's a few resources out there for indcutorless boost circuits, or charge-pump voltage doublers and triplers.

http://www.electroschematics.com/648/555-voltage-doubler/

But this circuit is only able to convert a meager 70mA and the conversion efficiency is not that great. What should be done to increase the amperage into the 2-3A range with efficiencies similar to the charge pump ICs out there

The reason I am looking at these is they are known for their potentially high efficiency, I think I've seen a few that claim voltage conversion efficiency of 99% and power conversion of ~94% such as the TC1240

It would be great to be able to convert DC from a single cell lithium battery to high voltage easily with low loss.

How do I get the max amperage up to 5A on this circuit? Is it possible without an inductor?


texts: How exactly does SystemC/SystemVerilog make the verification flow less laborious task

texts:
Now days SystemC or SystemVerilog are used for verification of complex designs, especially for things like SoC designs that are really complex. I do know that these languages bring in the OOP design techniques into the digital IC design domain.

What I don't know is exactly how do they make things easier when it comes to verification. I want to see an example side by side e.g HDL vs SystemC/SystemVerilog. Is there some resource that I can use to understand this?


texts:
When we comb our hair (with a plastic comb) and then bring the comb close to bits of paper, the bits get attracted to the comb. I understand this is because the comb is now electrically charged.

Why then, don't these same bits of paper get attracted to a live wire, or a terminal of a battery? Isn't the battery electrically charged?


texts: Compare mode, set output on match (CCP1IF bit is set) - PIC16F88 microcontroller

texts:
Hy.

I want to make a program who toggle a led using compare mode, set output on match (CCP1IF bit is set).
I dont know if it is possible what i want to do. Anyway the RB0 is always ON.
I know, it must be ON because when the value loaded in ccpr1 register matches with the value of tmr1 register the RB0 is set.
But if want to reset the RB0 output ?
I have doing this in interrupt() function writing the next statement : ccp1con=0b00001001;
And now the RB0 stay always OFF.

#include <system.h>
#pragma DATA _CONFIG1, _EXTRC_CLKOUT & _WDT_OFF & _LVP_OFF

void interrupt()
{
    if((pir1 & 0x01) && (pir1 & 0x04))
    {
        clear_bit(pir1, 0);      // clear TMR1IF
        clear_bit(pir1, 2);      // clear CCP1IF
        ccp1con = 0b00001001;    // clear output on match
    }
}

void main()
{
     trisb = 0xf0;
     portb = 0x00;
     tmr1h = 0;
     tmr1l = 0;
     ccpr1l = 0x60;
     ccpr1h = 0xEA;
     cmcon = 0x07;
     t1con = 0b00000001;      // prescaler = 1
     intcon = 0b11000000;
     pie1 = 0b00000101;
     ccp1con = 0b00001000;    // set output on match
     while(1)
     {

     }
}


texts: Can a DC regulator reduce/step down DC voltage?

texts: I have studied that regulators like 7805 are used to remove the ripples present in the DC power supplies. But while searching for information about 7805, I came across the circuit below. The circuit shows an LM7805 converting 9V supply to 5V. This is something like stepping down the voltage. can a DC regulator really step down a DC voltage (because I've studied only about their ripple removal function)?


texts: What does a two overlapping circles symbol mean in an electrical schematic/diagram?

texts:
In the datasheet for a A3503 Hall Effect Sensor, I saw a circuit diagram labeled 'Functional Block Diagram', and it shows a symbol I have not seen before. It's shown here between 3 - Output and 2 - Ground.

What is this supposed to represent?

The full datasheet is available here


texts: Why do we need to rectify or amplify the current/voltage?

texts: I am a beginner in Electronics. What i read now a days in my text book is about diodes,transistors etc. They are used for some rectification and amplification etc ? I wonder why do we need to give different shapes to voltage and current. For what these different wave forms of current and voltage are used ?


texts: Bypassing DSLR battery to power camera from power supply cheaply with bidirectional optocouplers

texts:
I am trying to power my Nikon DSLR with a permanent power source instead of the battery for long captures (overnight) without buying the overpriced battery adapter. I can't simply connect a AC-DC converter at correct voltage, as Nikon verifies the battery (or power source) and refuses to operate, if the power source is not verified. I have asked previously about a simple hack, which you can see here: simply connecting charger, battery and camera all together

This turns out to be bad, as charger's board might not handle the current spikes and the connection (charging? or not?). So the charger may be switched with a AC-DC converter. However, Nikon verifies the battery. I listened to the serial communication with a logic analyzer, which includes different data each time. I can't really decode it and if it is random, then cryptography is involved. More onto that you can find here. They even put FPGA chip inside the battery to handle verification (according to some blogs). I can't bypass the battery. However, I thought, I can use a bidirectional optocoupler to connect only the serial pin of the battery to the camera. That way, the voltage difference won't be an issue between the battery and power supply (as they will be isolated with an optocoupler) but camera will be able to communicate with the battery to verify it but won't have any clue, where the power is actually coming from.

Here is an illustration of this:

The communication happens at 33333Hz (30μs for each bit) 3.3V logic between the battery and camera. Battery voltage can range between 7.2-8.2V. Original power adapter operat The optocoupler needs to handle 33333Hz at 3.3V. Since, I am not very familiar with power electronics and don't want to kill my camera, I would like to ask you, what can go wrong with this setup (before I try and destroy my camera)? How can I do this safely?


texts: Imaginary Capacitance and Imaginary Inductance interpretation and relations with circuit theory

texts:
Today I came across with Complex Capacitances and Inductances for the first time:
$$L(j\omega)=L_{real}+jL_{imaginary}$$
$$C(j\omega)=C_{real}+jC_{imaginary}$$

So I started looking at their meaning and how they relate to the basic circuit theory that I've already learned. Let's start with the inductors.

Inductors:

I found this article, that states (pages 7 and 8):

After that, I found that this "Power Loss" is associated with "Core Losses", like hysteresis losses, Eddy/Foucault current losses. So, my first question is:

If \$L_{imaginary}<0\$, we have \$Power\space Loss >0\$, so we have a dissipation of energy by the magnetic core of the inductor due to (according to what the article says) eddy currents;
If \$L_{imaginary}=0\$, we have \$Power\space Loss =0\$, so no eddy current and no energy dissipation;
But, what if \$L_{imaginary}>0\$ ? Then we will have \$Power\space Loss <0\$, i. e., the magnetic core will supply power to the circuit! How is this possible? Or is the value of \$L_{imaginary}\$ somehow restricted by some equation, so that it cannot assume positive values?

(Another way to state this is considering the inductor impedance:$$Z_L=j\omega L=j\omega\cdot(L_r+jL_i\ )=-\omega L_i+j\omega L_r\ \ $$ The imaginary part of \$L\$ contributes to the real part of inductor impedance. This contribution is given in the form of a frequency dependent resistance \$-\omega L_i\$. So, if we have \$L_i>0\$ then \$-\omega L_i<0\$, a negative resistance!)

Capacitors:

I found this article. It states that (page 2) \$C_{imaginary}\$ is associated with dielectric loss.

Another source states that this dielectric loss can be by Joule's heating effect, hysteresis losses and dielectric absorption. I guess we can model this dielectric loss in a analogous way to the losses in the inductor core:
$$Power\space Loss=-\frac\omega2 C_i v^2$$

Thus, a similar question arises:

If \$C_{imaginary}<0\$, we have \$Power\space Loss >0\$, so we have a dissipation of energy by the dielectric;
If \$C_{imaginary}=0\$, we have \$Power\space Loss =0\$, so no energy dissipation;
But, what if \$C_{imaginary}>0\$ ? Then we will have \$Power\space Loss <0\$, i. e., the dielectric of the capacitor will supply power to the circuit! Again, how is this possible? Or is the value of \$C_{imaginary}\$ somehow restricted by some equation, so that it cannot assume positive values?

Relations with basic circuit theory:

I've already learned that real circuit elements can be modeled using parasitic elements. For example, a real capacitor can be modeled like this:

                                                                 Image source: Wikipedia

My final questions are:

The imaginary component of capacitance and inductance were used to "account losses" that occur in real components: hysteresis losses, Eddy/Foucault current losses, dielectric absorption ...
Are all those losses counted using complex values also counted when we model a real component with parasitic elements?
Which of the two models - using complex L and C or using parasitic elements - is the most accurate if we want a representation as close as possible to reality? Or are they equivalent?


texts: In a bjt transistor that is used as a switch (maximum saturation, Vce minimum as possible), what is the minimum  base current that is required for a corresponding desirable collector current?


texts: Wiring for a westinghouse electrical motor?

texts:
I've got an electric split-phase motor (no capacitor) with a centrifugal switch.
Specs
Westinghouse electric motor manufactured in 76.
RPM 1725/1140
1/2 HP
115V 60Hz
Thermally protected L Type
It seems to me that the terminals are bypassed as the power cord is directly connected to the motor.
When plugging the motor I hear a humming sound and I have to hand turn the shaft to make it rotate (any direction).
That tells me that there is a problem with the start winding. So, I checked the centrifugal switch, cleaned it with sandpaper and still no automatic starting of the motor.
Here's the schematic of the motor as I see it since there is no schematic printed on the chassis.

simulate this circuit – Schematic created using CircuitLab
There are 2 terminals for plugging a kind of molex connector.
I don't know how to proceed from here.
Should I make connectors to connect wires between them?
Note than SW2 have a side not connected to anything!
Here's a table of all the motor interconnections between them with their resistance:
+--------+--------+--------+----------+--------+--------+
|        | Green  | Yellow |   Red    | Orange | Black  |
+--------+--------+--------+----------+--------+--------+
|  Blue  |    -   |    -   |     -    |    -   |    -   |
+--------+--------+--------+----------+--------+--------+
|  Green |        |   2.4  |    4.3   |    0   |    -   |
+--------+--------+--------+----------+--------+--------+
| Yellow |        |        |    5.6   |   2.4  |    -   |
+--------+--------+--------+----------+--------+--------+
|   Red  |        |        |          |   4.0  |    -   |
+--------+--------+--------+----------+--------+--------+
| Orange |        |        |          |        |    -   |
+--------+--------+--------+----------+--------+--------+

A - indicates infinite resistance, i.e no short circuit
Also, testing each motor input against the motor casing gives an infinite resistance.
The previous schematic shows the actual condition I got the motor and it used a bypass with a power cord.
I see that terminal A3 have a cut green wire so I guess that would be the same green wire from the motor connected with the line BLACK input.
Also, for terminal B1 the cut wire is yellow so this would be the same yellow from the motor and this would be connected with the line WHITE input.
The next schematic shows what it would have been before the "hack".

simulate this circuit


texts: I'd like to understand the functions of Q2 and Q4 in the driver below. Also, why there's a shunt RC branch at Q5 base? Is Q2 simply a buffer or does something else? Also, in the diagram, it says "0.2mA" at the photodiode branch, with that current Q2 would be in cutoff even when no signal at Q3, so the laser would be off - that makes no sense...


texts: Could cold Solder be the cause of burnt components?

texts: I have a mainboard of a slot machine that has burnt resistors. I wonder if this could be related to cold solder, because the slot machine remains on for long periods of time (months at a time) and when the power fails, the difference in temperature could cause the solder to fail or become "cold solder". But, could this also cause burnt resistors and capacitors (or other components for that matter) or should that be attributed to voltage peaks?


texts: Covid-19: can a UV-C source be improvised from a standard mercury vapor lamp?

texts:
I suggest it because the usual professional UV-C sources are in short supply and very costly.

A common 175 W mercury lamp designed for illumination includes the quartz 'lamp' tube itself, inside an outer bulb designed to block UV-C (< 300 nm) radiation. If the outer bulb were removed, this kind of lamp would seem to be able to provide UV-C to destroy a virus.

I don't have a UV-C capable spectrometer nor a power meter filtered for UV-C only, so I can't test/do the experiment myself. Maybe someone else has such gear.

A document on this is here, and it includes references. I do not suggest that this be done except by those who understand the hazards of the experiment.

I believe that it's better to throw an idea on the table in front of engineers and technicians, than to hide ideas that may be helpful or to post untried projects on hack sites and prepper forums where they may do more harm than good. Known hazards include: UV radiation, high voltage, high temperature, broken glass.

If someone has the gear to try it, maybe it could help the situation.

The document is here, somewat hidden by obscurity.

ADDED 4/3/ 2020:
I should have stated that my goal was primarily to disinfect masks for re-use. I didn't want to limit the scope, being more interested in spectrum and power per square area at given distance.

I too, worked with an e-prom eraser, but from a repair perspective. The original UV tube was broken and unavailable. I put in two UV-C germicidal lamps. It worked perfectly and saved the customer money.

Some masks can be treated by heat or chemicals, and some may contain materials that are ruined quickly or are not properly disinfected by those and other methods. The type and construction of mask will dictate the best way to disinfect it for maximum re-use.

Treating every surface of an arbitrarily shaped object with sufficient UV intensity for sufficient time is a challenge. It's not impossible. Two UV lamps could be used, or a rotisserie arrangement, using an alligator clip to hold a mask, or any other arrangement, may be worthwhile. We can use our imaginations.

The risk of transmission from handling objects is significant and supported by expert opinion of an experienced doctor, James Robb, MD FCAP, here.

There was, and will not be, any suggestion whatsoever that anyone get some Covid-19 Coronavirus and irradiate it, then try to prove it’s worked. There are experts in the field who know how much UV-C intensity per area and irradiation time is required to inactivate the virus. There is such information for other viruses online.

While there are no studies specifically on Covid-19, Ozone has been shown to kill the SARS Coronavirus. Ozone is unstable and wants to revert to O2 and lose the third Oxygen atom. If the third atom of Oxygen does not find another Oxygen atom to combine with, it can break the virus so that it can't function. While Ozone can damage some materials, it does disinfect them.
There are several references, to scholarly work, in online articles to support the statement made in the comment.
Link1 to references
and
Link2 to references

At least one paper states that atomic Oxygen can recombine in a time scale of a few milliseconds. Our senses and the above references tell us that it can be produced in copious enough amounts to be effective in spite of this.

Solutions don't have to be clever, they only have to be workable. A Dallas, Texas mattress-cleaning company is already using its production line to sterilize masks for hospitals. It seems obvious but it's extending the lifetime of disposable masks from 1 day to > a week.

What the UV (and Ozone comment) information may mean for the public, who may soon be told to wear masks or face coverings outdoors, that that a mask could be safely used for a very long time. Ozone generation is another topic.

I clarify that I am not posting here for any pecuniary purpose. I have only one old set of PPE. Unfortunately it is only effective on October 31. A bit of levity keeps me motivated.


texts: Why would a switching voltage regulator circuit produce fluctuating voltage output?

texts:
I've created a circuit (image below) Using the LTC3623EUUD#TRPBF. The output should be 5v, however the voltage is oscillating up and down. What would be causing the oscillation?

I used solder paste and surface mount components for this.


texts: Is there an advantage of reducing the single sideband carrier in amplitude modulation over supressing the carrier completely?

texts: In amplitude modulation, one of the single sideband techniques is to reduce the carrier power instead of supressing it altogether. Is there an advantage to doing this and having some of the carrier signal or power still be present, as compared to suppressing the carrier completely? I mean technically, more power is saved when it is completely supressed. Does it have anything to do with demodulation?


texts: AVR USART OUTPUT almost similar as input

texts:
My output is different from my input when I try to read it from my Hercules terminal. Could this be from a bad UART initialization?

Inputs : | á, 1, 123

Outputs:|a, ±, ±²³

Code:

#include <avr/io.h>
#ifndef F_CPU
#define F_CPU 1000000 // 1 Mhz
#endif

#define USART_BAUDRATE 9600
#define BAUD_PRESCALE ((( F_CPU / ( USART_BAUDRATE * 16UL ))) - 1)

int main (void)
{
    char ReceivedByte ;
    UCSRB = (1 << RXEN ) | (1 << TXEN ); // Turn on the transmission and reception circuitry
    UCSRC = (1 << URSEL ) | (1 << UCSZ0 ) | (1 << UCSZ1 ); // Use 8-bit character sizes
    UBRRH = ( BAUD_PRESCALE >> 8) ; // Load upper 8-bits of the baud rate value into the high byte
                                    //of the UBRR register
    UBRRL = BAUD_PRESCALE ; // Load lower 8 -bits of the baud rate value into the low byte of the
    //UBRR register
    for (;;) // Loop forever
    {
    while (( UCSRA & (1 << RXC )) == 0) {}; // Do nothing until data have been received and is
    //ready to be read from UDR
    ReceivedByte = UDR ; // Fetch the received byte value into the variable "ByteReceived"
while (( UCSRA & (1 << UDRE )) == 0) {}; // Do nothing until UDR is ready for more data to
//be written to it
UDR = ReceivedByte ; // Echo back the received byte back to the computer
}
}


texts: I have a circuit that uses regular diodes, and I only have zener diodes in hand. As I understand, zener will conduct after a certain voltage in reverse, so all I have to do, is pick a voltage that is slightly higher than my circuit will send to the diode, and it should not conduct in reverse, and work like a regular diode. Am I right?


texts: How camera calculates amount of color per pixel

texts:
I don't know where to post this question sorry if it's in wrong section.
I already know how pixels works they are combination of three colors
RED, BLUE and Green. But they should be mixed in different amounts to
create a required color, I wanna ask how camera measures the amount of single
color to be mixed for the result color.

Thanks.


texts: I've read that semiconductors (i.g. intrinsic silicon) behave as insulators at absolute zero (since all valance electrons are shared via neighboring atoms). My question is, does conduction still take place? I'd imagine that there would be some finite voltage in which electrons could be pulled from these covalent bonds. Would this be some finite voltage?


texts:
While I was reading about filter design and going through the schematics, the following two questions popped up in my mind and I could not find a satisfactory answer to them:

A first order low pass Butterworth filter may be designed as shown below:

(source: ecelab.com)

…and a basic second order low pass Butterworth filter as:

(source: ecelab.com)

But if we are to design a higher order filter, we don't just put another RC segment in the non-inverting terminal, instead, we cascade a combination of first and second order filters. Why is it so, I mean, why don't we just add another RC segment? Closed loop stability issues?

A band pass filter can be constructed by cascading a low pass filter to a high pass filter with the frequency cut-off constraints. Does it make any difference which segment is added first, like 1st Order High-Pass Butterworth and then 1st order Low-Pass Butterworth, would it be any different from 1st Order Low-Pass Butterworth and the 1st order High-Pass Butterworth Filter?