texts: How plausible is the claim about a 200 kW battery solution?

texts:
Following this question posted on Aviation:SE:

Does the ARCA hoverboard violate known limits on small-diameter electric fans?

which is related to a hovering board described on the vendor site:

(source)

I would like to assess the claim this device really exists. In particular I wonder if it is possible to use the batteries to deliver 200 kW as claimed. I'm not trying to evaluate the aerodynamic aspects.

I don't see what technology could be used other than Li-ion cells. Assuming this is true, would this solution be compatible with the claimed characteristics:

Power delivered: 200 kW,
Running time: 3 min for a 110 kg user, to 6 min for a 82 kg user,
Charging time: 6 hours, reduced to 35 min using a docking station.

Taking into consideration the Li-ion characteristics with the knowledge of an electrical engineer, is there any aspect that would prevent this solution to work, e.g:

Weight, volume of the batteries (the board measures 145×76×15 cm),
Wires size (there is little room available in the box),
Current for charging (is this feasible to charge in 35 min),
Discharge time (would cells allow to be discharged in 3 to 6 min),
Cost (replacement of batteries is offered at $6,840).

No speculation please, but known facts that would definitely contradict or support the possibility of the solution. For instance, I think these deductions are correct:

For a 3 min hovering, with 200 kW, about 10 kWh are used.
Due to specific energy and density for Li-ion, this means 40 kg and 14 dm3 for the batteries.
Price of the batteries: With an optimistic 0.40 $ / Wh, this would be $4,000.
Charging 10 kWh in half an hour requires a 20 kW charger.
Assuming cos φ = 1, this would mean 91 A for 220V (well past what is usually found at home), and 5,000 A for the Li-ion cell voltage (this would require large wires that are not visible in the picture).


texts: DC-DC converter on custom pcb: lmr14050 drops 1 volt under load

texts:
I'm trying to use the LMR14050 chip for my shield for Raspberry Pi 4 to convert 12 V to 5 V and power the RPi, also I've a MCU stm32f105r8t6, powered also from 5 V by converting to 3.3 V by linear converter. So, my problem is: when I run the system in idle mode(powered only MCU) the Vout=4.85 V and it's even good, but when I connected the RPi, the Vout drops down to 3.7 V. Also, when I power up the system on some Vin lavels I get some noise from LMR and every time it's VERY hot, back side of the pcb is abou 70 - 75°C. Afterwards, Vout highly depends from Vin value. P.S. if I solder the soft-start capacitor the system would give only 0.8 V P.P.S. On the schematics resistors R9 and R10 was changed to 68k and 12k, also L1 is 3.3 μH.
Schematic:

PCB source:


texts:
I am working on a project that mandates the use of a particular Arduino motor driver shield, which makes use of an L298 dual H-bridge (datasheet here)

I need to perform some power calculations in order to size up my power supply, and ensure that I keep the driver's self-heating manageable. If my understanding is correct, in DC operation, an H-bridge will dissipate \$P = I^2(RDS_{on(H)} + RDS_{on(L)})\$

Unfortunately, the datasheet doesn't mention \$RDS_{on}\$. Is there some other way to calculate the power dissipated in a H-bridge that I am missing?


texts: Can I use a 16bit memory with an 8 bit processor?

texts:
The address bus is typically a double octet wide (i.e. 16-bit), due to practical and economical considerations. This implies a direct address space of only 64 kB on most 8-bit processors

This quote is from Wikipedia of 8 bit computing. It shows us that we can use a 16 bit memory with an 8 bit processor, and this sounds promising to the question of how to access more than 15 addresses from our ROM, but will this affect the usage of our processor itself? The only thing I need to keep 16 bit will be the address register, isn't it?im not using a processor but im interested in building one , this link - How can 8-bit processor support more than 256 bytes of RAM? , doesn't solve my problem


texts:
Power coming from unknown source

Hi, I have a quite complex circuit with 5 DC/DC Converters all being powered by a 28V power supply and with a common ground. All DC/DC converters have a on/off feature and they all are controlled by a Raspberry PI. I'm also using three PanStamps (Arduino compatible device running a 8MHz, 3.3V with a RF chip C1101).

The Pi is connected to a screen using a HDMI - DVI cable and also to an Ethernet port.

My regulators are TracoPower TMR 6-2410 (3.3V), 3xTMR 6-2411 (5V) and another 12V.

One of the PanStamps is connected to the Pi using their RX/TX lines and also connected to a 12V analog pressure sensor using a voltage divider to sacale down the output to 0-3.3V. All PanStamps share the same +3.3V line

The problem is that when I turn off the 3.3V regulator I still reading 1.48V on its output.

The problem is that this 1.48V sometimes is enough to keep the PanStamp running (instead of being off) which leads my system to unknown states and some times out of control.
When there is nothing connected to the regulator the off voltage is 0.09V.

I believe that this unknown power is coming from the Pi through  the RX/TX lines passing the PanStamp and going to the power line.

Here is my power schematic:

My questions are:
1 - How can I stop it from happening?
2 - Can some device be damaged by low voltage/current?


texts: Why do TTL integrated circuits have such complicated schematics for logic gates with so many transistors as opposed to RTL?

texts: I'm in the process of building a 4 bit computer out of discrete NPN BJTs and resistors. I'm using RTL, and I've made flip flops, full adders, and demultiplexers, and everything is working fine so far. Why are TTL chips that achieve the same things so much more complicated at the transistor level?


texts: Instantaneously changing currents in RL circuit

texts:
The first circuit is for \$t\$ (time) \$\le 0\$, and the second is for \$t \ge 0\$.

The book I'm reading says that \$i_L(0^+)=i_L(0^-)\$, but \$i_1(0^-) \neq i_1(0^+)\$ because there are no limitations on the current changing instantaneously at \$t_0\$.

What I don't understand is why \$i_L(0^+)=i_L(0^-)\$, but \$i_1(0^-) \neq i_1(0^+)\$?  Wouldn't \$i_L(t)\$ change instantaneously as to whether or not the voltage source would be connected?  Why is one instantaneously changeable and not the other?


texts: What operation does this circuit perform?

texts:
I have an assignment due for school, but this one question has been getting the best of my group-mate and I for about a week now. I am in no way asking you to solve the problem for me, but could you please make it a little bit simpler for us to understand.

Question:
If the input and output bit patterns in the circuit below are interpreted as binary representations of numeric values, what operation does the circuit perform?

My thinking:

1) If we put in a set of ones and zeroes as input then determined what the output would be , then convert the input bit pattern and output pattern to decimal, then we could try to figure out what base 10 mathematical operation was performed. Although when this was tried, there seemed to be no simple correlation between the input and the output.

2) Assuming that the question is not looking for a mathematical operation , and is instead looking for a logical operation, we tried drawing up a truth table, then go stuck("Where do we go from here? ").

Problems:

1) The question stated that the input and output bit patterns are binary representations of numeric values, we cant figure out why that is important , because when trying to do base ten arithmetic, it did not work.

2) Why did they put the '1' as an input?

3) assuming three inputs, how to you go about finding out what single logical operation is performed in the circuit.


texts: What is optical bandwidth and electrical bandwidth

texts:
I was reading a book about Optical Wireless Communication.

In the chapter where the transmitters are explained, there is a figure showing two types of bandwidth for LEDs.

This confused me a bit, why there are:

Electrical bandwidth
Optical bandwidth

What is the difference and the relationship between them? Moreover which one is relevant when it comes to the modulation (modulation bandwidth)?


texts: Heatsink on top of SMD plastic IC or bottom of PCB?

texts:
I often do designing power modules and always wonder if there is some kind of rule how to properly cool SMD devices.
I always look at final products from other companies and some are placing heatsink on bottom of PCB, while others pleace them on top - directly on SMD components with plastic packages.

Many power IC and MOSFETs do have large thermal pads on bottom, and thermal transfer should be really good to the bottom. But adding about eg 2mm FR4 of PCB is also good thermal insulator... Comparing to like 1 mm or less of epoxy resin on IO package, I dont think it could be worse...

To be more confusing, some power IC do not even have proper thermal pad - e.g. TPS63070 that I am working with right now.

What is better? Adding heatsink on bottom or on top? Does it depend on how thick Cu layers are?


texts: Parallel Resonance in Ultrasonic Transducers (Langevin)

texts:
I am working on a power-supply for ultrasonic welding machines and want to drive the transducer at its parallel resonance.
The Butterworth-Van Dyke model paramters are : L = 24.73e-3; C = 1.14e-9; Cos = 8.29e-9; R = 10.72;

simulate this circuit – Schematic created using CircuitLab
I wish to drive it at its parallel resonance. From a bode plot i found the anti-resonance(parallel) frequency to be ~32Khz.
I understand it is the frequency when the impedance of Cos||C and L are equal.
From most literature there seems to be a compensating inductor parallel to the Cos.
But adding the compensating inductor would shift the resonant frequency. I added a parallel inductor with a value of 2.7mH so that it would achieve resonance with the Cos at 32Khz.
But it seems to shift my resonance frequency higher up. (The series resonance is unaffected)
What role should the compensating inductor play in the power supply?
Can you set the parallel frequency by changing the compensating inductor or should it be driven at the frequency without the compensation (ie is the parallel frequency unique or is it tunable by the designer)?


texts: Easiest way to make printing head spray ink?

texts:
If I have a free-standing printing head including ink tanks, what would I have to do to just make it spray some ink? Are there some standardized signal encodings or something?

I'm not talking about generating an "output" with a moving head. Just a free head that should spray some droplets of ink.

And where would be a good starting point to find out more about such kind of knowledge?


texts: How can I send video from my Arduino camera module video to my Android screen?

texts:
I'm trying to connect a camera module to my Arduino Mega, connect my Mega to my Android phone (throught BlueTooth or other), and send the live view of the camera to the mobile phone.

I saw a video online that showed this for still images -- an image captured by the camera module on the Arduino was sent to Android and the output image was viewed after a couple of seconds (the time to send image by BT).

Is this doable with live video instead of image? If yes, please guide me; if no, please suggest some workarounds.


texts: Does a USB port provide enough power for my LED project?

texts:
I'm not quite sure whether or not my LEDs will draw too much current. I can't put the schematic right now, but basically I'm using just using the power line from the USB 2.0 port on my board, and it has to power:
x12 WS2812B SMD RGB LEDS
x1 ATMega32u4
also, if you could tell what kind of resistor I should put on the power line, if I need one at all, that would be super helpful.
sorry for not knowing anything


texts:
I'm planning to make a data logger project with 3-axis sensor and SD card. I would like to store 3200 samples per every second on SD card. Currently I could able to store only 630 samples per second.

Someone told me writing in  binary format is the solution.

Then I did accordingly.

fwrite(readings,sizeof(int16_t),6,logFile);

I can see .bin file with more data size compared to .txt or printf.

How can I get the readable ASCII format from .bin file?

I tried by using fread.

FILE *logFile = fopen(fileName,"rb");
int readings[6];
nr = fread(readings,sizeof(int16_t),6,logFile);

How can I see the readable ASCII data?.

Thank you.


texts:
I want make hidden wires (AC, 220V) detector (circuit is below), based on Soviet p-channel JFET transistor КП103, but JFET's now is very rare. Can i replace this JFET by any low-power MOSFET?

My mistake, sorry. I attach КП303 circuit instead of КП103. But principle is the same.This is equivalent transistors with different channel type.


texts: In a FF when clear is 0, output is also 0.So what should it be considered as ? Active low or high clear? If it active low doesn't it mean that output should be 1 ?


texts: How should a radio receiver be used to detect damage to concealed wiring?

texts:
Several structures hereabouts date back to the mid 1920s. Electrical wires were insulated by cloth winding, and embedded in Wooden Trunking

With the passage of time the cloth rotted away in some places (typically near a junction/bend) leaving raw wires in the wooden channels. Come rain, and there may be the occasional experience of an electrical kit kat fuse growing warm, even hot!

The electrician says, in his experience, even opening the channel cover for inspection strips all the cloth insulation off the wires for a few feet both up-and-down the work area.

What I'd like to do is determine any points where the cloth insulation has already rotted into dust.

With 220V 50Hz in the line, I figure there may be some radiation around the wiring which could be detected by the right receiver. Similarly where the insulation is exposed, perhaps, the radiated signal may be stronger. Obviously it won't be an intelligible signal - even strong/stronger/weaker static may serve.

My questions

Is this idea feasible?
What is the strength of such radiation?
What frequency band should such receiver aim to detect?


texts: Correct wiring of Cortex-M 10-pin Debug Connector

texts:
The ARM Cortex-M 10-pin debug connector has five interesting signals, in the original PDF they're named:

SWDIO / TMS
SWDCLK / TCK
SWO / TDO
NC / TDI
nRESET

For MCUs which only support SWD and which might even not have SWO (such as the STM32F030), I'm assuming the wiring is as follows:

SWDIO / TMS: PA13 ("SWDIO")
SWDCLK / TCK: PA14 ("SWCLK")
SWO / TDO: Open
NC / TDI: Open
nRESET: NRST (Chip reset)

Is the assumption that nRESET means chip reset correct?

Because if it is, how about a larger device like an STM32F103:

SWDIO / TMS: PA13 ("JTMS/SWDIO")
SWDCLK / TCK: PA14 ("JTCK/SWCLK")
SWO / TDO: PB3 ("JTDO/TRACESWO")
NC / TDI: PA15 ("JTDI")
nRESET: NRST (Chip reset) or PB4 (JNTRST)

Here, it's not clear where to connect nRESET anymore: To the chip reset signal (NRST) or the JTAG reset signal (JNTRST)?

Additionally, is it good practice to hook up both SWD and JTAG connection to a device that supports both (like the STM32F103)? If such a device should be only connected to SWD, does the meaning of nRESET change (i.e., when using JTAG maybe it's connected to JNTRST, but when only using SWD it's connected to NRST)?


texts: Can you parallel the transistors in ULN2003?

texts:
As the title say, can you parallel the transistor pair in ULN2003? The datasheet of the IC say it has a max output current of 500 mA, but I need 1 A.

So is it possible? (if you know any other transistor array IC that can drive 1 A on each pair that would be a great help also)


texts: Is the following equation wrong in this BJT DC bias analysis?

texts:
I came across a section of a tutorial regarding BJT DC analysis as follows:

The first two equations for Ic and KVL for the BE loop seems correct.

But I'm stuck at the last equation inside the box for the Ic.

It seems to me the factor for the Ico must be (β+1) but it is something different in the equation above. I checked it ten times and couldn't figure out and be sure whether I am or the material is wrong.

Here is how I write down:

Ic = β×Ib + (β+1)×Ico

Ib = (Vbb -Vbe) / (Rbb+(β+1)×Re))

These yield:

Ic = (Vbb -Vbe) × β/(Rbb+(β+1)×Re)) + (β+1)×Ico

I find the factor for the Ico as (β+1), but the material's result for this factor is:

(β+1)×(Rbb+Re) / (Rbb+(β+1)×Re) which is not equal to (β+1).

Is the original derivation or am I making a mistake?


texts: Why does the output voltage after full bridge drop so many?

texts: recently I am researching the piezoelectric transducer (PET), which can convert the mechanical energy into electricity. And I found a strange phenomenon. I used the 10MΩ probe of oscilloscope to connect the two electrodes of PET, it measured about 9.9V output voltage and the current is around 1uA obtained by other equipment. However, after I connected a full-bridge rectifier after the PET, the output of rectifier is only around 2.4V. I remember it should be 9.9V-2*(forward voltage of diode), that is about 9.5V. I couldn’t find what is the problem. I just simulated this using TINA-TI software. The result is that the case as well. The PET can be modelled as a sinusoidal current source in parallel with its internal electrode capacitance and resistor. When I increased the current from 1uA to tens of uA, the output voltage after full-bridge circuit is correct. So I wonder why small current of PET will cause this problem. Can anybody help me solve this confusion. Thanks a lot!


texts:
I have an instrument that I am trying to integrate some pumps with. It has 3 Open Drain pins,a ground, and a +5V pin.

I've successfully used 3 NPN transistors to act as a +5V switch to drive a relay when the Open Drain pins are high.

I have a problem when the instrument first turns on (or recovers from a power failure). It turns all 3 Open Drain pins high and turns on all 3 relays until it finishes initializing. I'd like to avoid this.

My idea is to use one of the Open Drain lines to act as a +5V supply when it is low (the initialized state) so that the other two lines will only be active when the instrument is fully initialized. How can I do that?


texts: Protecting Copper Anode in 12V DC System

texts:
Getting to grips with cathodic protection here.

If someone had a 12, 24 or 48VDC system, say solar PV and batteries, and the battery negative is earthed, this means the earth is the cathode, and the positive rail of the electrical system becomes the anode.

Is it right that in moist conditions only, that the copper of the +ive rail is now more likely to corrode than the -ive?

Is it correct that this copper +ive can be protected by attaching a zinc or magnesium block to the copper itself?

I've seen the effects of a corroded anode in old 12V solar systems, the black copper oxide is difficult to clean up.


texts: Choosing components for a triac's snubber

texts:
I'm interfacing the BT139-600 TRIAC with this MOC3051-M Opto-triac. I want to build a snubber circuit for the TRIAC as shown in the MOC3051M opto-triac's datasheet @ page 8, figure 12.

The load will be a 230V AC, 4A motor. What are the recommended characteristics of the Rs, Cs and MOV in that schematic (the type of the resistor and capacitor, power specifications, voltage limits)?
Would this components be a good pick for the snubber?

Cs: Ceramic Capacitor 10nF

Rs: 33 Ohm 5W wirewound resistor

MOV: JVR14N431K 275V AC MOV Varistor

Do I also need a snubber for the triac driver?


texts: Charging 2 LiPos in serial used as split rail

texts:
I was wondering what the recommendations are for creating a charging circuit for 2 LiPos when they are connected in series, but as a split rail, shown below.

Currently I am just disconnecting them and charging them using the sparkfun charger PRT-10217. Previously I have implemented a charging circuit around the MCP73831 for a single LiPo, so I was wondering if it were possible to use two of those in this type of configuration:

This is of course assuming that I disconnect the batteries from the rest of the circuit first!

Is there anything else I need to be careful of? Thanks


texts: I am new to eagle and I need to practice routing. I've read many general tips (about using jumpers for example) to use while routing, however I want a precise step by step procedure I can follow to manually do the routing for any circuit. Should i for example start by one part of the schematic and look at his corresponding part in the board? Any ideas?


texts:
I need to create a subtractor on LT spice using an LT1028A to emulate the difference between 90V and 23V; resulting in 67V. I have tried using a variety of resistance pairs, but in vain. Could anyone kindly help, the output is stagnant at 15.84V?
Vo = (V2 - V1); I have used R1 = R2; R3 = R4

Pic Courtesy: Getty Images, 2014


texts: How can I stop supplying power to a circuit when power drops below a certain threshold?

texts:
I'm looking at using a 12V LDO with a 1-2V falloff, so if a vehicle is running the alternator overcomes the 1-2V falloff and the device circuit becomes powered, but I know that I don't know what then happens at 12.4V (nominal battery charge).

I don't know if it continues to supply some unsteady voltage and drain the battery or does it act as an immediate hard power kill.

Is there a better solution to the problem?


texts: Is it normal to have this much fluctuation in an RTD measurment in boiling liquid?

texts:
I'm using a MAX31865 RTD measurement IC, and a standard PT100 RTD to measure maple syrup temperature as it's boiling (219 degF).  At ambient, the temperature measurement is reasonably stable.  But, when boiling, I get a substantial amount of drift.  I need stability preferably in the range of ±0.1 degF.  In my data below, I'm already applying a pretty heavy rolling average.  And, the data you see was taken in seconds, so it's fair to say I don't have an electrical noise issue (and there's really no frequency component).  This looks like random drift.  Do I have a measurement problem, or is this a physics problem?  Does boiling liquid drift like this?

UPDATE:
I took the suggestion of @sstobbe and replaced the RTD with a resistor of similar resistance that would give me a 219 degF reading.  The reading is solid as a rock.  The stability is actually within the precision of the device.  I see a very infrequent change of around 0.016 degF (I should mention that I'm using an oversampling routine to increase the resolution).  So, I am convinced that this is a physics problem.
Next, I think I will use use the suggestion of @10ppb and try to increase the thermal mass by using a metal block of some sort.  Unfortunately, agitating the syrup, or giving it some sort of recirculation, is not an option.  Any other mechanical suggestions on how to overcome the measurement volatility induced by the boiling?
UPDATE 2:  I tried a couple things last night with a boiling pot of water.  I wrapped the end of the RTD with about a half inch of aluminum foil.  There was perhaps a 10-20% improvement.  Then I put a test tube upright in the water bath, added a little bit of vegetable oil in the bottom of the test tube, then put the tip of the RTD in the oil.  The thought being, the oil wouldn't boil (and cause measurement fluctuations), but would be a good conductor of heat.  While the water was at 212 degF, I couldn't get the oil past 204 degF.  I waited at least 20 minutes.  I'm sure it would have reached equilibrium at some point, but it was clear this isn't going to work for my application.
Also, someone had mentioned that they were surpised that my data wasn't more erratic.  It actually is quite erratic.  The data shown has a heavy rolling average applied.


texts:
Looking through the internet, I came across following circuit.

MCU GPIO generates 0V or 3.3V Level.

VDD may be 5V or 30V. I would like to use the same circuit for both purposes, which is to supply the load with VDD with certain source resistance when MCU GPIO is ON.

My question is that

1) Why did they use voltage divider on the NMOS side? If PMOS can tolerate VGS difference of VDD, can I remove the resistor in the middle?

2) What is the purpose of capacitor between Gate and Drain of the PMOS?


texts:
Altium is driving me crazy right now. I Annotate my schematic, but I do not know why Altium wants to always switch / exchange U109 sub-parts. RC4558 op-amp. I put them in one order and Altium changes it. WHY?
I have tried everything that comes to my mind. Many times removed the part, updated the PCB. Saved and closed Alitum and then put a new part in the same place. So why is this happening and only to U109, even if I change it to let's say U113, this only still happens to this op-amp and it's sub-parts? Is this a bug? What could I do to prevent this from happening? What is the reason and the problem?


texts: Problem in measuring potential because of oscilloscope's input impedance

texts:
I am trying to use a sensor, whose resistance value change from infinity to around 10kΩ when variable load is applied. The load is applied for a small duration and in order to capture that I'm using TDS6000 series oscilloscope. I'm trying to use a potential divider circuit as shown below (Rs- resistance of sensor).
On multi-meter I'm able to get voltage range of 0-1.6V across R1, but on oscilloscope I'm barely able to get a few mV. This is likely because of the input impedance of the oscilloscope (Ro=50Ω), which makes the net resistance of lower part (A-GND) very small as compared to Rs.
I have tried a couple of combinations of resistors but haven't got any success yet. I want the variable voltage in the range of 0-1.5V. Does anyone have any suggestions?


texts:
I'm designing an automotive scan tool. For now, I'm studying about ISO 9141 and LIN Bus physical layer compatibility. I have a legacy hardware that uses L9637 to perform ISO 9141, through K-Line, but I want to add LIN capabilities in the new hardware.
Does ISO 9141 and LIN BUs use K-line the same way ? I mean, can I use L9637 as a transceiver in a LIN BUS ?


texts: Does repeated NAND flash erasing cause more wear?

texts: That is repeatedly erasing pages without programming them. Or does it have to be a erase/program cycle to count?


texts: How to detect SD Card Insertion Without Leakage Current

texts:
I'm using a TI CC1111 SoC to read/write a microSDHC SD card, with an Amphenol card socket. The card detect (CD) pin of the socket is connected to ground when no card is present.  When a card is inserted, the connection is broken. (This seems to contradict the datasheet, but it's what my multimeter tells me).

One way to detect card insertion would be to connect a GPIO pin to the CD pin. By default the CC1111's pins are configured with an internal pull-up resistor. If a card were present, I'd read logic high, and otherwise the pin would be pulled to ground. But I worried this might draw excessive current, and sure enough, the CC1111 datasheet warns (pg. 90):

Unused I/O pins should have a defined level and not be left floating. One way to do
this is to leave the pin unconnected and configure the pin as a general purpose I/O
input with pull-up resistor. This is the default state of all pins after reset except
for P1_0 and P1_1 ... Alternatively the pin can be configured as a general
purpose I/O output. In both cases the pin should not be connected directly to VDD or
GND in order to avoid excessive power consumption.

Question 1: Where is the power consumed? Is it just in the internal pull-up resistor? The datasheet says the internal pull-ups are 20k, so with 3.3 V that's about 0.17 mA. Is that what they're talking about? Or perhaps the "excessive power consumption" warning only applies when the pin is configured as an output?

Qustion 2: What is the right way to detect card insertion/removal without wasting power?

And no, I haven't measured the current draw yet, but I will.


texts: Multi-plex 8 BLDC motors using shift registers?

texts:
I want to drive 8 tiny diskmotors - they look like low current motors. robotshop 2mm vibrating disks

I want to drive perhaps 2 or three of them at a time with pulse-width modulation signals and I would like to do it from a single driver since they are uni-directional. This would assume the same pulse width for all activated motors.  Assuming the current requirements are met by the driver;

Question:  Can I drive them all from one circuit with a shift registers or with a multi-plexer.  If so, how?

Is there a way to drive them with one motor driver that allows for variable pulse width as well?


texts: I'm trying to simulate a guitar pedal with LtSpice. Do you know how I can input a guitar recording to the circuit? I will then convert the output to a txt to listen to it from Matlab sound function.


texts: Shortcut to change layer/add via whilst routing in Eagle

texts:
I am working on a board which requires a lot of vias and changes of layer whilst routing. I can change layer with the dropdown but that's going to take ages when I've got in excess of 64 vias to do.

How do I assign a shortcut that changes from layer 1 to 16 / 16 to 1? I've assigned a simple 'change layer' but all that does is bring up a 'select layer' window which is just as slow.

Thanks


texts: Understanding the MPX2053 Pressure sensor

texts: So I am a bit confused as to how I would operate a pressure sensor whose pressure range is between 0-50 kPa because the moment I remove it from the packaging and expose it to the environment, it will experience 101 kPa (1 atm) which is outside its pressure range. At the same time I feel that the sensor would be useless if I cannot take it out of the package, so how does it not experience the 1 atm pressure entered by the atmosphere?


texts: I have 8 DDR3 chips connected to an FPGA (2 controllers) and two DSPs, where 4 DDR3 chips are connected to each of the processors. At this moment I have one VTT regulator TPS5120 on board, will that be enough? Should I include more VTT regulator each near to DDR3's?


texts:
I had a working design of a buck switching regulator based on a TPS62125. It worked fine, with minimal (<100mVpp) noise. I made some changes to my design, seemingly unrelated to the switcher. The result is audible noise from the switcher (a high pitch whine, that gets louder as draw increases), as well as this lovely waveform:

Here's my current layout:

The only changes I made to the switcher directly is adding room for a 250uF electrolytic cap (problem persists with and without it), adding a .2mF supercap elsewhere in the design, but off this power rail (problem also persists with and without), and adding a footprint for C33, but not populating. The amplitude of the noise does not seem to be affected by load.

Where do I go from here? How do I troubleshoot this? I thought I spotted a short between the two pins of the IC that lead to the two pads for the inductor. It doesn't look like there's an actual bridge while looking with a loupe, but could this be the source of the problem (pins are too close because of excess solder, creating some sort of stray capacitance)?

The only other thing I can think of is that it's possible that I installed a wrong capacitor for the input or output caps (did this by hand). Would that produce these results? Could it be a bad inductor?


texts: Do any distributors pack in bags of 10 or so?

texts:
I want to buy components from places like Farnell, Mouser, etc. But I then want to distribute them in kits, each kit would have maybe 10 of each component; the components are tiny 0603 types.

The problem is, there are nearly 50 bags in each kit, and removing the required components from the right bag and rebagging them sounds like it will take a long time, and it seems wasteful as many distributors already have these bagging facilities. It's also not an option to make an order for each kit, because that's looking to be £50 each.

So do any distributors offer the option of splitting each order into little bags? I've already shot off an email to Farnell about this possibility, but I'm not hopeful - I'm wondering if any distributors just offer it as an option on their website somewhere.


texts: Stepping down 25V-11V to power 5V micro-controller

texts:
I need to power a control circuit from a variety of LiPo batteries 3-6S (12.6V to 25.2V). The control circuit can draw up to 100mA at 5V (atmega328p + other discrete components, LEDs, etc).

Choices I know about:

Voltage Regulator LM340T-5.0 stepping down any voltage up to 35V. The problem is power dissipation. Because the solution has very limited space, no heat-sink is available.
Buck/Step-Down Converter LMZM23600. 5-times more expensive and difficult to handle, due to strange packaging (pins on the bottom).

Is there any other straight-forward way to power control circuit from 3-6S battery ?


texts: I2C Strange Behaviour with RTC and MPU6050

texts:
I encountered a very strange i2c behaviour in my project.

I use an Adafruit Feather M0 (3.3V) as i2c master and 3 slaves (MPU6050 Gyro Sensor, DS3231 RTC, M24C01WP EEPROM) schematic below

The EEPROM works flawless, the Gyro returns 0 on all existing registers and the RTC only works in minutes and seconds. Date and Hours are always returned wrong.

Due to the Adafruit Feather M0 and the standard Arduino library, the I2C bus runs on 3.3V with 100kHz. I used 1kOhm Pullups.

All the Datasheets tell that the devices are compatible with 3.3v and 100kHz. Also the 3 devices have different i2c addresses.

I built the device twice, so i dont think that the gyro or rtc are broken.

Again the devices respond to requests. Only the values are wrong.

MPU6050: https://www.invensense.com/wp-content/uploads/2015/02/MPU-6000-Datasheet1.pdf

DS3231: https://datasheets.maximintegrated.com/en/ds/DS3231.pdf

Edit: C1 is between 3V3 and Ground, NOT scl and data


texts: can the inductor and resistor values be found from the impedance

texts:
If the inductive impedance is given can the separate resistor and inductor values be calculated?

OK

The question gives the voltage supply (magnitude and frequency), power factor and current. It also states that the circuit is inductive as the current passes through a single coil.

To satisfy the question the inductor and resistor values are required. Can this be calculated with the information given?

I can find the impedance as a phasor quality using the V/I cos^-1(p.f), but cannot expand this into the separate values for the resistance and inductor.

I don't think its possible and wanted to know if it is possible from more experienced people.

Thanks

Danny


texts: Is There a Symbol for an Inrush Current Limiter?

texts: Is there a schematic symbol for an inrush current limiter, or is a resistor used instead?


texts: How to design a AC-DC circuit using only the hot/live wire has power input?

texts:
I was looking at these new IOT devices coming from CN that are designed to replace your standard wall switch with an ESP8266 smart-switch.

It seems there are two types: A) the typical one where the AC-DC circuit needs to be feed with a Neutral and a Hot wire and B) one which only requires the Hot/Live AC (220V) wire.

What kind of circuit are we talking about and how could we implement one from scratch ?
Bonus points for example schematic. :-)


texts: Transistor bias circuit for 2N3904 - why some popular transistors does not work?

texts:
I have set up the simple common emitter amplifier circuit based on 2N3904.
The circuit was first simulated in Multisim and than breadboarded. All works fine as expected. I have tested about 20 different transistor models (also vintage ones and PNP) on breadboard and most of them are working fine with that bias and give about the same voltage gain at the output. But some does not at all (no amplification) like 2N3391A and 2N3417. My question is why the don't? They are "general purpose" so i guess they should work with the same bias as 2N3904 or 2N2222?

Note: In Multisim simulation ALL transistors work also 2N3391A.


texts:
Apologies this has probably been asked before - I have been looking but I think I don't know the terminology to answer my question.

I have a micro-controller based project and I want to power it with three LiPo 2000 mAh cells in parallel. I think I understand how to do that part the issue is with charging the batteries - which I know how to do separately but the design is such that the batteries cannot be removed.

Ideally, I want the batteries to charge quickish (couple hours). I thought about using USB but 500mA would be a slow charge. I would like to use a standard UK wall plug which I think is 12v which would be too powerful for the components in my projects (4.7V).

So I need to kind of turn the current off (is this called a circuit breaker?) just when the batteries are charging but want this to work automatically and then when they are charged I can remove the charger and  turn the project on manually with a push button.

Another thing is I need to keep the charging components really small too like under 20 mm width and 60 mm length. I would like the wall plus to be mini USB ideally.

Also if the battery charging is kinda on a separate circuit (or part of the circuit is turned off - including the micro-controller) could I use AC rather than AC-DC

I hope that makes sense. Any help is hugely appreciated


texts: How to send data to an ESP32 with as little delay as possible from an Android app

texts:
I have an ESP32 module. I want to send data to it using an Android app.

I tried using http but the delay is big especially since I want to send about 20 values per second with a delay between 50 to 100 ms.

So I am looking for a better way to do it.


texts:
Consider the following charge-time graph :

If we need to calculate the current in the interval 8 to 12 seconds the current will be negative (since the current is the differentiation of the charge with respect to time , that is the slope of the graph and in this interval the slope is -ve) , so what is the physical meaning behind this negative current or what has happens to the charges to make the current negative in this interval ? According to my understanding the negative current means that the current is in an opposite direction but here the charge has decreased so how this is related to this negative current ?


texts: Audio Noise: ATMEGA328P, MCP4921, and LM386

texts:
I am trying to build a simple audio circuit.  The goal is to store .wav files in the form of hex files in the ATMEGA328P's flash memory, and output the audio through a small speaker by using an MCP4921 DAC and an LM386N-1 Op Amp.

I uploaded a portion of my EAGLE schematic.  The value of AMP_FIL_R is actually 0.05uF, instead of the 100uF indicated on the Eagle Schematic, and this is per the LM386 datasheet.  Also, the code that I am running is attached.  I started off with the code from here and added some code to play my hex file.

The Problem:
Although I am able to output a meow, it is coming out with a lot of noise.  So, it sounds like the final sound I actually desire is fully there, but high frequency noise is added on top of it.

The Question:
What could be causing this noise?  I have read a number of things could cause this. First, the LTC1514-5 power regulator I am using is in the 650kHz switching frequency range, so not sure if it is affecting the audio? Second, the LM386 op-amp itself, should it be farther away from the speaker? Unreliable connections in the breadboard? Proximity to bench equipment such as oscilloscope/meter/DC power supply?

//"meow.h" file is stored as PROGMEM, char type variable

#include "avr/io.h"
#include "util/delay.h"
#include "HRL_SPI.h"
#include "HRL_MCP492x.h"
#include "meow.h"

void setup() {
  Serial.begin(9600);
  // Initiate SPI in Mode 0 with MSB first, NO interrupts and a clock of F_CPU/4
  setupSPI(SPI_MODE_0, SPI_MSB, SPI_NO_INTERRUPT, SPI_MASTER_CLK4);
  SETUP_DAC;
  _delay_us(100);
}

int config = 0x30; //Mono, unbuffered, 1xGain, SHDN off
word output = 0;
word a=0; //index for meow array

void loop() {

  if(a==sizeof(meow)) {Serial.print("again!"); delay(2000); a=0;}
  output = pgm_read_byte(&(meow[a++]))*16; //Multiplied by 16 to go from 8 to 12 bits

//  Serial.print("index:");
//  Serial.print(a,DEC);
//  Serial.print('\n');
//  Serial.print("output:");
//  Serial.print(output,DEC);
//  Serial.print('\n');
//  Serial.print('\n');

  writeMCP492x(output,config);
  _delay_us(125);
}


texts: Raspberry Pi Zero HDMI socket - available current?

texts:
I have an ongoing question on the Raspberry Pi SE site, in which I'm attempting to figure out how much current is available to devices connected to the HDMI socket of each Pi model. I think I've figured out every model aside from the Pi Zero.

There are no schematics available for the Zero but, following some extreme squinting, I think that the most likely candidate for HDMI power management is the component labelled D6. It's immediately below the white printed 'HDMI' label to the right of the mini HDMI socket, which is towards the bottom left corner of the board.

The part is marked 'F03 | CD'. Some stumbling in the dark on Google turned up the Diodes Incorporated DFLS130LQ / '1.0A SURFACE MOUNT SCHOTTKY BARRIER RECTIFIER', which has identical markings.

Is it plausible that this part might limit current to pin 18 of the mini HDMI socket? If so, what is the maximum current that it would allow to pass?


texts: emitter to base amazing transistor effect

texts:
As I'm a beginner I was playing with transistors connecting them parallel, serial, making AND/ OR logic gates and so on. I connected all collectors to + and each transistor emitter to another one's base.

The wire of the first base acts a little amazing for me.
When I stand up, move my body, touch it, move my hand in the air on top of it, move a paper in the air on top of it, LED turns on and after a while turns off.
When I place my finger on it, a coil, sheet of metal, antenna, LED turns and remains on and doesn't turn off after a while.
I guess it gets very low electric induction from the environment and makes current in it and with amplification of transistors led with turn on. But the more confusing thing is that when I connect a diode to the wire of first base and place my finger there, it turns on :| while no current should go there. How is it possible?
What if instead of 5 transistors, there will be 100 transistors? Can it be used to detect any small movements in a room?

Please test it and I have a movie of it if you wanted I upload it.
Thanks


texts: Why there is no current in the inductor during the first positive half cycle of the ac voltage?

texts:
Suppose switch is closed at t = 0. Right after the switch is closed there will be the voltage rise from the ac source. As the voltage rises from the ac source there should be a corresponding rise in the current through an inductor during the first positive half cycle of an ac voltage, as there is also a change in voltage during the first positive half cycle of the voltage from the ac source.

Then why in the graph we see no change in current in the inductor during the first positive half cycle rise of ac voltage from the source?


texts:
I'm still new to EE, and taking a introduction class right now. I have a simple question regarding nodal analysis.

Suppose that we have three things connecting in parallel,

One 12 voltage source with a resistor in series
One resistor by itself
One dependent voltage source where its voltage is equal to the voltage across the first resistor

These three are connected in parallel, the negative terminals are connected each other for the voltage sources.

Suppose I want to use node voltage to analyze this circuit.

What I have so far is, choose the node connecting the negative terminals as the reference node, and the node connecting the positive terminals as Node 1.

Then $$I_1+I_2+I_3 = 0$$

But how can I calculate the I_3 when there is only one voltage source there without any resistor?


texts: Conductivity of liquids (3D resistor network)

texts:
Hi I'm an electrical engineer but have not seen this problem before. I'mn trying to measure/calculate the resistance of a liquid.

Background:
I'm working on an electronic device that can come in contact with a liquid. Unintentional, can be avoided but is not considered a big deal. It's easy to clean and does not corrode/hurt the print.

What I noticed is that it misbehaves when in contact with the liquid. I've found that the liquid sometimes was conductive enough to cause a small bias current on a transistor, introducing a large bias on the output. Just enough to break the function.

Problem:
I want to calculate the resistance of this liquid. But I've not found a solution for it yet. For instance I can measure the conductivity but to me it's not straight forward going from Siemens/cm to Ohm over a given distance. I assume the measured conductance is a from a 3D resistor network of unknown value.

Example: Glass tapwater 22 deg C, measured at 264uS/cm. I use a cheap Chinese TDS&EC so this measurement might be off. R= 1/S or R = about 3k8 at 1cm.

What would the resistance be at 2mm? Or at 1mm?
How can I find this value?

I'm not looking for a solution to my circuit, there are many easy fixes. I want to understand the conductivity/resistance problem first.


texts: Non electrical background trying to make a cool little custom project - Help please?

texts:
Brief bit of background -  I've built my own PC's, I've repaired phones, changed plugs, fit light fittings from diy stores, and have a basic (very basic) understanding of electronics, but have found myself wanting for various reasons trying to build a custom project with light bulbs in series.

I've got mine and my partners initials in 10 inch high wood pieces from hobbycraft, (these style) and wanted to add some bulbs (these type) in series, to prove an aesthetic/design concept. I would use these light bulb holders and this battery pack to power it all.

The end result would ultimately look something like this (just not dog related...)

My question relates to whether using the bits I've researched and chosen, whether it would a) work, b) be bright enough, c) look decent. Each letter I anticipate will use 15 mini bulbs.

Could 4 AA batteries power all 45 bulbs or shall I split into 3 circuits of 15 for each letter?
Would I be better off on mains power or is that way too much?
Can I connect all these bulbs in series?

Any other tips and advice welcome.

If this works, I'd like to then recreate this on a bigger scale for our wedding day, which would sit at the side in the venue - I like the idea of creating this, as I'm quite craft-sy, and enjoy building things and again I have a very specific vision of what I want, which isn't achieved by hiring them.

I've chosen to build rather than buy because also nothing out there is exactly the way I want it - I want lots of smaller bulbs, instead of bigger ones. I also don't like the white globe look, and want the bulbs to be filament style.

Any help? Thanks in advance!


texts: On a relay coil, why use an MOV instead of flyback diode?

texts:
I briefly encountered a designer who wished to use an MOV instead of a flyback diode with a relay coil. I don't know much about the application, but why would you want to do that?

The only reason I can think of is that the coil is normally energized and seldom de-energized, and the MOV acts as a speed-up circuit for de-energization, burning the inductive energy faster than a flyback diode.

That said, why not use a zener or a resistor, especially given that MOVs have limited lifetimes? What other options are there?


texts: Simple piezo buzzer circuit--could I power it using a large battery?

texts:
I am fairly new to electronics. I was thinking about a simple circuit and was wondering if it would theoretically work or not. Say I wanted to connect a 12V Piezo buzzer to a switch and a large battery (press momentary switch, buzzer buzzes, release and it stops). Say I wanted to use a large battery, like a lead-acid 12V battery found in a car. I realize this is probably a terrible circuit design and much better ones for buzzers already exist, but I want to know why it wouldn't be a good idea. My real question is this: if I have a  12V Piezo buzzer connected across a large battery, is this basically shorting out the battery by connecting the terminals together? Is it bad for the buzzer or the battery? Or would the battery's internal resistance allow this to work?

Edit: The piezo in question in question is a self-driven 12VDC 58mA buzzer.


texts: NPN transistor to run 12V 0.5A from 3.3v 4mA

texts:
I assume this question is very common, because I read a lot of answers here, but I still missing somthing..

I have "Electric Imp" module, which have max I/O pin power output of 4mA, and its run on 3.3V.
I need to run electric door, which consume 12vdc 500mA at max.

So i started and checked the 2N2222A transitor:
Ic(MAX) = 1A - good enough.
Vceo(MAX) = 40V - good enough

and now I am geting to the base needs (the gain):
in the Hfe I see that the closest is Ic=500mA, Vce = 10V (I need 500mA and 12V, so it is close enough), the gain for this will be 40, which means I need 500/40 = 12.5mA as output.. I do not have it.. am I right so far?

Another thing I am missing is - where can I see in the datasheet that 3.3V is enough on the base, BJTs is not Voltage , but current base, right?

if I am right so far, so I need 500mA/4mA = Hfe of 125, but I couldnt find such resistor.. I can add relay 12vdc coil with lower current than 500mA and use the NPN to run the coil so it will run the door lock..

Thanks, Gabi.


texts:
I want to make a constant current source for a few dozen (say 30~60) 2-lead bipolar LEDs by combining a constant-current (CC) source circuit with an H-bridge circuit:

simulate this circuit – Schematic created using CircuitLab

Here the CC source can provide a constant current, but only in one direction.  The H-bridge can drive both polarities of the LED, but is a constant-voltage source (VCC or GND).  Here's my combination:

simulate this circuit

Operation:

When signal A is active (low), the CC source with Q3 is biased active and VCC is applied to the anode of D1, causing it to illuminate.  Since signal B is inactive (high) the CC source with Q5 is inactive since Q8 is inactive, and VCC cannot 'reach' the collector of Q3.  When the signals are reversed, an equal but opposite operation occurs so D2 is illuminated.  Software will ensure both A and B are not active simultaneously.

Questions:

Anyone see any inherent problems with the circuit?
I don't have a ton (or well-suited) high-power PNPs lying around, so can anyone think of a way to substitute in my abundant TIP120s (Darlington NPNs)?


texts: Most cost-effective way of making an electronic "slot machine" with a hundred wheels?

texts:
The closest description for what I'm looking for is an electronic slot machine with a hundred wheels. Each wheel has, say, 8 faces/drawings/symbols and I need to be able to create any of the 8^100 permutations in the most cost effective manner.

The wheels are mounted on a shaft (can be a geared or smooth shaft, whatever needed), and can be spun all at once stopping one at a time or (preferably) just spun and stopped one at a time (so it's not exactly a slot machine).

I've considered many possible solutions, but I'm looking for a method that's as cost-effective as possible so a motor per wheel is definitely out, a solenoid per wheel is less than ideal. I considered mounting a motor onto a belt (a la inkjet printers) moving from one to the other from behind and doing the spinning, which is a very clunky and imprecise solution.

I'm assuming this is a solved problem, but one I'm just not familiar with. Does anyone have any ideas or prior art I can look at for inspiration to solving this?


texts: Hi, I found this device lying around somewhere and I have no idea what it is. Can someone help me figure out what it is?


texts: Is it a good idea to enlarge LGA chip pads for hand soldering?

texts:
I'm designing a board where I'm using an LGA-14 and a WSON-12 chip. Is it a good idea to make the pads bigger, so I can use a soldering iron to apply solder to the pads, place the chips, then reflow the solder with the iron from the exposing bigger pads? Are there any risks doing this?

(I will have a stencil, but I don't have hot air, or reflow oven)


texts:
I am very new to electric engineering, so bear with me ;) Before building the circuit IRL, I wanted to try to build a simple 555 timer with a simulator following Ben eater's tutorial on it. Here are the schematics of the circuit...

If you want to see the tinkercad project... Now, even though I seem to have copied the exact same circuit as shown in the video (or at last so I think) - the first seconds of YT video - the 2uf capacitor doesn't seem to discharge trough Pin 7 when I simulate the circuit. What could be the problem here? I am 100% sure I am missing something very obvious but I have tried, and tried and tried to no avail. So I hope you guys could explain this to me :)

Thanks in advance!


texts: Determine gain for a variation of the differential pair

texts:
In order to prepare for an exam I am trying to solve the following problem: For the circuit shown below (a variation of the differential pair) I want to determine an expression for the gain \$ A_v = V_{out}/V_{in} \$. Backgate effect can be neglected. Furthermore, all transistors can be assumed to be in saturation. I have problems figuring out how to do that.

If I work with the formula for \$ A_v \$ and write
$$
A_v = \frac{V_{out}}{V_{in}} = \frac{V_{DD}-R_D I_{DS2}}{V_{in}},
$$
I already do not know how to go on. I cannot say how the current \$ I_B \$ splits up and therefore cannot determine \$ I_{DS2} \$. Can anyone help me out?

simulate this circuit – Schematic created using CircuitLab


texts:
My project with PIC16F887 has strange behavior that I can't explain. This simple c program (I removed the unimportant part) on a PIC16f887 does something weird. Port A is partly switching on en off with RA1.
In debug variable (picture at the bottom) you can see that RA0..RA3 and RA5 are actualy low (1us). I must be doing something wrong.

#include
#include
// CONFIG
#pragma config FOSC = INTRC_NOCLKOUT     // Oscillator Selection bits (RC oscillator)
#pragma config WDTE = OFF                // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = OFF               // Power-up Timer Enable bit (PWRT disabled)
#pragma config MCLRE = OFF
#pragma config CP = OFF                  // FLASH Program Memory Code Protection bits (Code protection off)
#pragma config BOREN = OFF                // Brown-out Reset Enable bit (BOR enabled)
#pragma config LVP = OFF                 // Low Voltage In-Circuit Serial Programming Enable bit (RB3/PGM pin has PGM function; low-voltage programming enabled)
#pragma config IESO = ON
#pragma config FCMEN = OFF
#pragma config CPD = OFF                // Data EE Memory Code Protection (Code Protection off)
// CONFIG2
#pragma config BOR4V = BOR21V
#pragma config WRT = OFF
#pragma config DEBUG = ON

#define _XTAL_FREQ 8000000

void main()
{
    OSCCONbits.IRCF = 0b111;    //internal osc at 8MHz
    TRISA = 0;
    //----------------------------main loop --------------------
     while (1) // main loop
     {
         RA1   = 0;
         PORTA = 0xFF;
     }
}


texts:
I am using the MSP430F5438A-EP microcontroller. I wanted to know the max current that could be sourced by this chip. The datasheet is -Datasheet.

The data given in page 38 states - Diode current at any given pin = 2mAmps. The diode, I believe, is the protection snubber circuit in each GPIO. Right ?
Hence, I am safe in assuming that each pin can source a max of 2mAmps ?


texts: Why do cables that carry RF have 2 leads

texts:
I just got a ham radio license, and I am trying to figure out the mystery of RF.

From the output on your transceiver to an antenna or an RF amp, there is a 2 lead coax cable. If antennas only have one wire sticking up, what is the point of a 2-lead system to carry the RF.

What happens to the outer wire when at the antenna, is it just a pointless wire, which gets discarded, or does it have other uses? I don't see 2 wires on the antenna, just a thin piece of metal going to the air, which only 1 wire can be connected to.

The only thing I can think about is the 2-wire system prevents the wire acting as an antenna itself and maybe the 2-conductor system makes it more like a transmission wire.


texts:
I read a course about power transistors and I encountered these graphs

The chapter is talking about safe operation of BJT. Can anyone tell me what those graphs are ? (And how to read them).


texts:
I am working on a design that requires Two Chips - Energy measuring chip (for analogue measurement) and a MCU (for connecting to a communication peripherals, and connected to a PC.) Both Chips is to be powered by a 3.3V DC supply.

But the ground for both chip has to be different. How can I possibly go about that? Please refer to page 3 of ADE7878 Eval Board Power supplies. I intend to use a SMPS for this design.

Thanks a lot.


texts: Hobby breadboard wiring guidelines to stay within legal RF/EMI limits?

texts:
Assume a middle school or home hobby lab with a bunch of breadboards, jumper wires, and 3.3V microcontrollers fast enough to toggle IO at RF frequencies (if not at the fundamental, at lower harmonics of the toggle frequency).  Assume a digital IO toggle frequency right in the middle of some random HF or VHF band.  Assume that the school or hobbyist are unlikely to have access to a calibrated spectrum analyzer.

So, to help encourage best practices:

Are there any good jumper wiring guidelines to reduce the chances of a breadboard (or set of breadboards) radiating EM outside various limits (FCC Part 15 in the U.S., etc.)?

e.g. maximum length of jumper wires, maximum loop area with respect to the nearest ground return, minimum termination resistance of a circuit loop, etc.?


texts: I2C connection randomly dies with error 4

texts:
I am trying to interface an ESP8266 microcontroller with an ICM-20948 IMU chip.
Using the reference code from Invensense, the internet and trial and error, I managed to configure the chip do do 9-axis sensor fusion using its internal compass and DMP.
I am using a mosfet(BSS138)-based level shifter and a linear voltage regulator to provide the ICM with its required 1.7V VCC / logic voltage.
For the first 5-30 seconds, everything works fine and I get perfect drift-corrected quaternions. However, the data stream then just apruptly stops and the call to Wire.endTransmission() fails with error 4 (which very helpfully means "other error")
Does anyone know what the reason for such behavior could be?


texts: What is the simplest way to convert convert 5V DC to 100V DC, 0.2 Amps?

texts: What will be the simplest way to convert convert 5V DC to 100V DC, for low power application ~0.2 Amps for a portable electrophoresis power supply?


texts: What are the generic standards to obtain clean proper AC mains input

texts:
I'm confused with choosing a generic topology for mains surge protection and chokes. I cannot find a good overview explanation on the topic. My question might sound not so specific but I cannot understand the big picture since there are many variants.

Here lets look at couple of examples:

Is there standard generic topology for surge, transient and over current protection?

Is there a single AC mains connector in the market which provides all? Well I can myself at least install the fuse across the hot line. But imagine you have a device outdoors and you want to suppress overvoltages transients all sorts of problems. There are chokes, there are NTC, there are MOV ect ect.

What is your favourite topology when building an electronic box which will stay outdoors prone to over voltages ect. Imagine you just built a box with some electrical circuit in it and the AC mains will feed your DC adapter inside which will supply energy to electronics circuitry. Imagine the max current you want to limit is 2A. I would be glad to see your example diagram for this purpose. Diagram how one provide a safe proper input to DC adapter from AC mains. I would like to see how the suppression and other possible issues eliminated in a generic way.  An example diagram helps to understand.


texts: How to see the solder mask layer in Altium PCB?

texts: Is there a way to see the solder mask layer (green coating layer) of a PCB in Altium? Is it a mechanical layer?


texts:
How can I tell if the LT1013 will work with -4.5 volt and +4.5 volt supply voltage?

In the datasheet just says that it works with 0 and 5 volt, and -15 and +15.


texts: Ways to connect a PCIe/PCIe2 card and other PC parts to a breadboard?

texts:
Basically I have a bunch of rather old computer parts that I haven't been able to get rid of so I decided to do a few experiments with them but for that I need to be able to breadboard them.  Things like old CPUs, ribbon cable hard drives, RAM, various cards (sound, wifi, ethernet, and graphics).  For instance, one such project is to be able to write to and read a hard drive with an Arduino or see if I can cobble together some kind of working computer based on a graphics card.

I've tried Google searching adapters but to no available.  Can anyone tell me where to find one or special order (if I have to)?


texts: Why does inc R of a RL circuit increase dVL/dt. Here I have circuits and details

texts:
Why does increasing R of a RL circuit increase the rate of change of voltage across an inductor with respect to time dVL/dt. Here a 50V 2k circuit and a 5V 200ohm circuit both create a change of current from 0 A to 25 mA t = 0 and that current is opposed by a back emf. Both circuits exhibit an increasing current because the inductors create a self-induced voltage proportional to the rate of change of magnetic field strength across the inductor with respect to time dϕM/dt. The way I understand back emf and VL is the current created by the voltage source Vs/R is passed to the inductor then the inductor receives current Vs/R. That current passes through the first loop, not exactly, I am just imagining this. Then the change of current 0 A to 25mA creates a magnetic field that increases in strength like the voltage across a capacitor increases when it is supplied a constant voltage x V. The rate of change of the magnetic field strength creates a self-induced voltage. The self-induced voltage creates the voltage drop across the inductor. So the voltage across the inductor is like the current passing through a capacitor that is proportional to the rate of change of voltage across the capacitor dVC/dt.
Increasing inductance (L) decreases the rate of change of the magnetic field strength with respect to time dϕM/dt like increasing capacitance C decreases the rate of change of voltage across the capacitor with respect to time dVC/dt.
Increasing resistance (R) decreases the rate of change of voltage across the capacitor with respect to time dVC/dt. So why does increasing resistance (R) increase the rate of change of magnetic field strength with respect to time dϕM/dt.
Next, here, is a statement I am not confident about, continuing on resistance: The current passed to the inductor is 0 A to 25 mA in both circuits. The inductance (L) is the same.
So how is the resistance (R) increasing the rate of change of magnetic field strength with respect to time dϕM/dt, dVL/dt, and dIL/dt.


texts: MEMS Microphone noise floor power level & audio noise spikes measurement

texts:
I have a circuit with a MEMS microphone and would like to be able to measure the audio noise spike contents and check the noise floor power level in the audio circuit.

My intention is to connect the oscilloscope to the MEMS microphone but before that I would like to know the procedure to analyse the signal shown in the oscilloscope. This is, do measurements need to be done in specific ambient control? Is it necessary to use a specific audio signal for the MEMS microphone to receive and transduce?

On the other hand, maybe using audio fft analysis tools could help. Is there a free one that can be use for this purpose?


texts: Does anyone have an easy to use Servo Torque Calculator?


texts: Decoupling capacitors for 7400 type chips

texts:
I am currently designing a circuit involving several 7400 TTL series ICs that include SSI ans MSI chips, so I may need to include several decoupling capacitors for the circuit design.

Documentation for decoupling capacitors for a group of 7400 series chips is difficult to find, so I don't have a good idea for how many chips should share a 0.1uF ceramic capacitor.

I need to know how many SSI, MSI and LSI chips of the (THT) 7400 series should share a single capacitor. How should I place the capacitors for them to be most effective? Would the CMOS 4000 series share the same properties?


texts:
The task says:

  Determine Z if power on R (R = 3 Ω) equals 666 W. Apparent power equals S = 3370 VA and power factor is 0.937(capacitive).

This is the picture od circuit:

I tried to solve it like this:

\$ P_R = I^2 * R => I = 14.9 => U_{RL} = U_Z = 99.95 \$

I know that \$ P = cosφ * S = >P = 3157.69\$ Then as i know that real power on parallel branch is 666 W i know that real power on Z branch must be 2491.69 and then \$P_Z = \frac{U^2}{R}\$ gives me R = 4 that supposed to be real part of Z, the same way i thought to get imaginary part ,but that is wrong, answer is Z = 2 - 2i


texts: Why do shorted PSU probes stick together just a bit, even on very low power?

texts:
I'm using a standard bench power supply set to 3.6V and 0.5A. I also tried 0.05A.

I then bring the positive and negative terminals together in a short circuit, and I noticed there is a noticable sticking effect between them. I have to use slightly more force to separate them, than when the power supply is turned off.

Is this some kind of electromechanical phenomenon, or is there some degree of welding going on here?


texts: Using a brushless DC motor for generator

texts: Is it possible to use a brushless DC motor as a generator? If we use the brushless DC motor in the following configuration, the brushless DC motor is used in front wheel of a rover/small car, and the power transmission is done by rear set of wheels, is it possible to recover energy from this configuration? Can we generate electricity from the DC motor in the following configuration?


texts: What is the purpose of STM32's noise-wave generation function?

texts:
if you see in ST32f103ret6 unser manual or datasheet, you can to see a feature of DAC unit with this name: noise-wave generation.

now i have several question about this feature:

What's the usage of this feature? making sound noise or electromagnetic noise?
If yes for electromagnetic noise, how did you use of it? did you connect it to a antenna?
What was your experience of use of it? please say to me that how did you use of it?


texts: Should the LED be on the lens side of a light pipe, or the other way?

texts: The image below is from a Bivar cutsheet.  I'm trying to figure out which end the led should be on.


texts:
I want to design a multifunction device that has a laser pointer as one of its attributes.  The laser pointer module I'm considering uses two AA batteries but these batteries are too big/heavy for the device.  Are there any flat baterries I can use instead?  My device needs approx 3-5mW output.

I don't know the diff btw volts, amps or watts; but I'm starting to learn.  Please point me to any good educational resources.


texts: Can I connect Inductive Proximity sensor to two different PLC

texts:
Some background, I have a tractor that I want to make semi-autonomous.

The tractor has it own PLC and an NPN Proximity sensor to measure speed.

I have industrial PLC by Unitronics (V130) with I/O that can act as NPN or PNP.
I wish to connect my PLC to the same sensor and save me a hassle to install another one next to it.

I wonder if it safe (no harm to a sensor or either of the PLC) to split the sensor wires and if it possible to sense the sensor in both PLC?

The sensor model is NBN8-12GM50-E1-V1 by Pepperl-Fuchs
Datasheet: https://files.pepperl-fuchs.com/webcat/navi/productInfo/edb/293454-0057_eng.pdf?v=20180423144546

EDIT:
The two PLCs don't share the same power source and ground

Thank you


texts:
I'm thinking of making an 8MHz about-square clock starting from a 24MHz about-square clock. All signals are CMOS with 3.3V(±10%) power.

What are my options? I'd like it low-power, cheap and easy to source, compact.

Note: the divide-by-N 74HC4059 does not match my "8 MHz about-square clock" requirement; the output duty cycle is about 1/3.

Update: I located that On Semi application note trying to do what I want, except that's using a lot of circuitry more ICs than in my dreams. I wish that divide-by-3 function existed pre-integrated...

Update following comment about the lack of symmetry requirement: the available 24MHz at input has tlo>16.5ns, thi>16.5ns, and negligible jitter. The output signal should have tlo>50ns, thi>50ns, and no long-term drift. Thus if my math is right, in the above circuit I have to keep the difference of delay between (rising-input-edge to rising-output-edge) and (falling-input-edge to falling-output-edge) within ±8ns (with 166ps engineering margin).


texts: Switch Configuration for Variable Gain Photodiode Amplifier

texts:
In this article here:
https://www.analog.com/en/technical-articles/optimizing-precision-photodiode-sensor-circuit-design.html#
It states:

However, I don't understand the rather critical line "instead of looking at the voltage on the output of the amplifier, switch, Switch S2 connectsthe output of the circuit directly to the gain resistor. This eliminates any gain errors due to current flowing through Switch S1."
What exactly is it trying to say here? Because I don't understand what it's trying to do with that second switch. The same resistance is still in the feedback loop, and the same currents flowing in the feedback loop still flow through the switch. All the second switch seems to do is isolate the unused feedback path even more, but that doesn't seem to be the intention.


texts: Is it possible to remap the PWM output to other pins?

texts: The Arduino Uno has PWM outputs on pins 11, 10, 9, 6, 5, and 3. Is it possible to remap the PWM outputs from these pins to other pins ?


texts: What is technical difference (internal voltage) between Digital multimeter's current measuring ranges mA (milliampere) and A(ampere)?

texts:
Is there any difference in internal power supply (DMM's) while knob turned to mA and A.
While measuring current in my microcontroller-module with keeping mA on DMM, I am getting brownout detected (current loading ?) but not when kept at A range given current measured =35mA. Basically if current is in mA range why  keeping knob at mA should produce any errors ?


texts: Where is the ground/negative for overhead power lines?

texts:
I recently learnt that ground can be used to complete circuits using high voltages.

I'd like to know if this is how overhead powerlines work, and if so where exactly do the cables/circuit terminate - at substations or something?

For that matter, the negative (black) mains wire in my house, where does that go?

I had a google around but I wasn't really sure what to look for, hence asking here. If someone can point me in the right direction I'd appreciate it!

Thanks!


texts: How to choose a perfect resistor to LEDs to get same brightness?

texts:
I'm using 5 different LED to indicate water level. I used a 330ohm resistor to all LEDs. Some LEDs glow brighter some are less bright.
How can I calculate an exact resistor value to my LEDs to get equal brightness?


texts: Finding Vout and Gain of a differential amplifier

texts:
I am given this figure below:

And I am trying to find Vout and the gain.

From looking at this source: https://www.electronics-tutorials.ws/opamp/opamp_5.html I have determined the gain to be 10k/1k * (v+ - v-). I was just hoping for some confirmation on this answer that I got...

I also tried to find Vout, however, in doing so I neglected the 1k resistor to get: Vout = -10k * C * d/dt(Vin)

I only neglectected the 1k resistor as I am not sure how to go about finding Vout with that resistance there. Is neglecting the 1k resistor wrong?

I appreciate any help,
thank you.


texts: Best utillization of M9K memory in max10 or other altera fpga's

texts:
I've got a max10 with a nios processor built in my memory utillization on the part is: 414,198 / 562,176 ( 74 % ) but I've used up every M9K block on the FPGA. Here is a table for the utillization

As you can see, a lot of the M9K blocks are being used for a small buffer on some of the nios II components. My question is: Is there any way to get better utilization from each M9K block? It would be nice if I could combine them somehow, and seems a little ridiculous that I would use a whole block for 256 bytes of memory.


texts: A question on diodes and resistors at the OR gate inputs of a 7432 IC

texts:
I'm trying to understand the reasons for the Schottky diodes(D1, D2, D3, D4) and 100 Ohm resistors used in the below schematics section:

The OR gates are from this: 2−Input OR Gate 74LS32

The diodes used are BAT85S

As far as I know the inputs IN_C, IN_2, IN_1&A&B are pulses with either 0/6V or 0/12V types.

The whole circuit works in real, but I have the following questions:

1-) What could be the reasons for the diodes and the resistors in the inputs of the OR gates of the 74LS32?

2-) Can this 74LS32 handle 6V or 12V voltage inputs at its OR gates?


texts:
I would like to understand the design of the L239D IC. I have read the schematics and datasheet and know how to use it but I wish to know a little more about its design.
The left part of this image shows half of the circuit for one motor (I think,) for the input high of pin 2 and low of pin 7 it should be connecting the motor to rotate in one of two directions. The problem is I can't determine from this schematic which direction the motor will rotate for either input.

I have seen a simplified image for the same circuit except for using 4 transistors in it to control the direction and it makes a lot of sense in contrast of the first image of the IC:

I just need a simple detailed explanation of the IC working in the first image.


texts:
I've seen in several places this snubber circuit composed of 2.4K and C1 in this particular case.

My question is - what's the purpose of this network exactly and how are the values for the resistor and capacitor calculated?

Does it provide a phase shift so that power triac could be turned on on zero crossing and if so, how does it work?

It's said, that it is designed for power triacs with sensitive gate Igt < 50mA. What do I do if my power triac's gate is not sensitive (> 50mA)?


texts: Help identifying pins in EVQV9C00116E rotary encoder

texts:
I'm trying to make a button box for a sim racing rig and need a few rotary encoders for menu browsing. I plan to connect it to an arduino but I can't seem to figure out how to wire things up. I have found the datasheet for the encoder, but can't figure out what pin does what.

How do I connect and use the EVQV9C00116E rotary encoder with an arudino?


texts: Connecting two SLA batteries of different but close capacity in series

texts:
I've read here that it is not recommended to connect two SLA batteries of different capacities in series.

What if you have two SLA batteries that are of close capacity such as one 12V 9AH and one 6V 7.5AH connected in series. Both batteries will be individually charged. Is the risk still present for damage to the 6V battery during discharge? If so, what would be the recommended cut off voltage for the 6V to mitigate against this damage? If the 6V is left to continue to discharge without a cutoff voltage could the SLA start reverse charging and possible leak/explode?


texts:
I'm new to op-amps and trying to find whether this is a common op-amp circuit. I've looked through this op-amp circuit collection but I couldn't find it.

Is this a well-known / commonly used op-amp circuit? If so, which one is it?


texts: Bluetooth Module Normal and Standby Mode configuration

texts:
I am using a BT module that can be pulled high for normal mode and pulled low for standby mode. The I/O pin 26 is connected to the MCU GPIO.
Theory of Operation:
When BT_WKUP = 0 --> BT module goes to standby mode
When BT_WKUP = 1 --> BT module goes to normal mode
Default-->BT modules is in standby mode
Are there any suggestions to improve this implementation?


texts: In any electrical equipment having single ph 230 v ac supply ,if neutral and earth wire exchanged then what will be the consequence

texts: I am handling the supply in a locomotive coach and have noticed that the neutral and earth wires have been accidentally flipped,inside the appliance(hot case) is there a problem from the safety point of view?


texts: Can I use an N-MOSFET to turn off a voltage divider?

texts:
I'm using a simple voltage divider to measure the voltage of my battery. The battery will be in the neighborhood of 12V, and the uC runs at 3.3V. I don't need to read it often, and don't mind a few extra components to turn it off when not needed. I went down the high-side switch path on a tip from the interwebs, but now I'm thinking why not just put a low-side N-MOSFET instead? Given the voltage difference I need a driver transistor to run the high-side switch, and wouldn't for a low-side one. Any reason not to? Here's the current circuit:

EDIT So - I remembered why it's not ideal, but I'll continue the question anyway. If I disconnect the circuit between R11 and ground, there's still a current through R5 and into the uC. However, the question then is how much current is flowing through in that scenario? The uC is an ATMega2560, which has an input pin impedance of 10 MOhm, implying a negligible amount of current (on the order of a few nA). Am I going about this the right way?


texts: LED Matrix design without micro-controller

texts: I am working on a project concerning the creation of a LED matrix (4 x 6) but without using a micro-controller. It will be powered by a 13V battery and the leds will be controlled by a switch. My question is about the resistors. Should I use a resistor for each led or a resistor for each line and if the latter should it be placed at the start or the end of each line ?


texts: How do we convert price per kVA to price per kW?

texts: I have been told that since kVA is a smaller "unit", price per kW is higher than price per kVA. I'm not entirely sure kVA and kW are not simply units as Power Factor is not really a conversion factor. But I could be wrong in my interpretation. Can someone please confirm this logic? Thank you.


texts: Current regulation before or after voltage regulation?

texts:
I'm making a +12V/-12V power supply (2.5A max. output current each) with voltage regulation and current limiter (+ option to go lower on voltage than 1.25V). In the datasheets, I've came across, that in the Datasheet, page 8, FIgure 20 that there's a current limiter BEFORE the voltage regulation, which didn't made much sense to me.
Isn't is supposed to be the voltage regulation first in a "row" here? Because if the current will be limited too low, there's not even necessarily that I could get 1.25V on the input of the "voltage LM-317"?

In the second photo, there's my schematic for the power supply with voltage segment before the current limiter. Is this the more correct one or is the one from the datasheet the one, which I should use?

I marked with red the voltage segment, while the current limiter is red.


texts:
I am trying to make a small board with an RGB LED on it. I would like to power the board with a nice small 12mm coin cell (3V). However the typical forward voltages of the RGB LED (and minimums) are slighly higher (~3.5V).

Would it be kosher to use a non-inverting op amp circuit to bump up the VCC slightly to achieve the proper forward voltage for the LED? Will this damage the battery or cause it to die faster?


texts:
I need a voltage controlled switch that is able to turn on and off using voltage in the range 0 to +10VDC. When it's on it should be able to handle the flow of +24VDC across it.
I had a look on the internet and asked on others forms as well, but not quite sure about this. MOSFET was one I though about it, but it requires its gate voltage (Vgs) to be higher than the source. But I cannot get the gate voltage to higher unless I OP-amp, which is making this a bit more complicated.

For MOSFET I have a diagram done, maybe it's not right but I tried.

Adam-4024

This is ideally what I'm looking for. The Adam module (ADAM-4024) is only capable of applying 0 to +10VDC max. Not use if it's possible.

Is there any simple circuit/component that is capable of doing this.

Thank You

*
Thank you for the diode suggestion. I have found a 2N7000 N-Channel Enhancement Mode Field Effect Transistor would this would be prefect, I added the datasheet link hereMOSFET 2N7000 datasheet. Also I'm not particularly sure about the Rd(on) value.

Also another thing to mention, Peter Smith suggested a diagram below, when you were talking about in the comments you said "a 0-volt control input may destroy the MOSFET" is that applying to the diagram below and not the diagram I drew?  Yes? I asked this as I will be supplying 0V to turn off the MOSFET.

Furthermore, I'm not sure if I'm correct to say this but,  if I use MOSFET to active the SY3220 by switch and when I want to switch off the SY-3220 still active because the MOSFET self lock it. Is this correct or I'm wrong and I can perfectly turn off the SY3220-5L device.

Thank you for the help


texts: What is this sheet metal cutout on the PCB?

texts:
This PCB is from a car body control module which contains a bunch of relays to control various motors (windows, door locks, etc.). There is no RF devices on this board. This sheet metal cutout looks like it's connected to two of the relays and goes to an IC. What is it? It seems like it's some sort of current sensing device.
Additional Pictures and info:

The two HKFD relays control the door locks
The following two tyco relays control the rear windows and have a similar sheet metal cutout
The right two relays control the front too windows and are the sheet metal cutout in question.
The sheet metal has connections which feed to a IC labelled "PM25AL" which for the life of me I can't figure out what that is.
The sheet metal is shared with the two identical relays.
The windows are controlled via a 12V motor with no additional sensors on the motor. Maybe this sheet metal device is used to determine when to stop exciting the motor?


texts: Boost converter - low inductance and discontinuous or high inductance and continuous?

texts:
I'm working on a battery powered application and I need to step up from ~3v to ~25V.  I'm trying to balance the peak battery loads vs the overall performance.

I'm torn on the inductor.  I'm at ~2MHz operation and if I set it to 15uH the system runs continuous and the peak battery current is roughly ~275mA due to turn on (basically charging C2).  However, if I set it to 2.2uH the system runs discontinuous and the peak input current is down to ~195mA, basically due to the cycle-by-cycle peak current in the switch terminating some of the cycles early.
Here's the real question - is there a downside to the discontinuous operation?  Am I going be generating more noise (electrical, magnetic or audible; inductor will be "shielded")?  Will I be stressing anything here that would cause an early failure?


texts: What is the least amount of time that I can measure using STM32F1x Timers?

texts:
I am working with STM32F107 on a custom board, the board has 12MHz crystal. I want to measure 1 micro second precisely, but I am unable to do so.
I have used STM32CubeMX to set the core clock at 72MHz which is it's maximum speed.
Trying to use Timer 3 in upcounting mode and toggling a GPIO in the ISR of the Timer.
These are my settings

void MX_TIM3_Init(void)
{
  TIM_ClockConfigTypeDef sClockSourceConfig;
  TIM_MasterConfigTypeDef sMasterConfig;

  htim3.Instance = TIM3;
  htim3.Init.Prescaler = 0;
  htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim3.Init.Period = 72-1;
  htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  if (HAL_TIM_Base_Init(&htim3) != HAL_OK)
  {
    Error_Handler();
  }

  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
  if (HAL_TIM_ConfigClockSource(&htim3, &sClockSourceConfig) != HAL_OK)
  {
    Error_Handler();
  }

  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim3, &sMasterConfig) != HAL_OK)
  {
    Error_Handler();
  }
  HAL_TIM_Base_Start(&htim3);
  HAL_TIM_Base_Start_IT(&htim3);
}

I get a approximate 2 micro second pulse on the scope.
Tried fiddling around with the prescaler and period values but I am unable to get a 1 micro second pulse.


texts: Use a momentary switch with a toggle switch

texts:
I've got a machine I'm making (A raspberry Pi with a picade Hat), which has a soft power off functionality (one click to power on, one click to power off).

I'm putting it in a toy which had a key to close the original circuit (turn right to power on, turn left to power off).

There are two pins to manage an external button, but the functionality is the same (If I close the circuit it powers on, if I close it again it shuts down).

Is there a way to make it work as I want it (power on when closing the curcuit, power off when opening it) ?


texts:
My issue
I have recently been looking at a circuit named a "slayer exciter". From what I have read it is a form of SSTC (solid state tesla coil). I found a good video about it on youtube which you can find here. I have checked other versions of this question on this website but nothing seems helpful. I am using a secondary coil with ~800 turns and a primary with 3 turns. I have used the schematic from the video above, but since I don't have a lab power supply or any 9 volt batteries available to me, I decided to use a 5v usb connector to power the coil. I have completely replicated the circuit from the video and used all the same components (TIP32C transistor, 47K Ohm resistor etc.) However, when I power it on, I saw no output from the secondary (yes, the primary and secondary are wound in the same direction), and worse, when I probed around with an LED connected to a crocodile clip to ground, I saw no output from the resistor, but when I probed directly behind it, I found +5V. I also looked around the primary coil, which had +5V on it, and yet when I looked for the purple arcs from the secondary, I saw none. I even touched it and felt no shock. You may say: "but slayer exciters are not able to deliver much power". Well, I used my LED on it and it didn't seem to explode so that's not the issue.
Schematic

(replace the  9v battery with a 5v usb power source)
I will try and get some 9V batteries but until then it would be very helpful if someone could tell me what I did wrong, or what could be the cause of the lack of voltage in the secondary.
Extra details

I am using a hand-winded coil, which I spent ~4H winding.
The primary coil is not a perfect circle, more of a squiggly line circle, if that makes any sense.
My usb sockets are USB 2.0

Thankyou in advance :)


texts: aluminum anodizing power supply schmetic

texts:
It has been a long time since I played with the electrons. In my day filament transformers were common and power supply design included the number and type of tubes being used.LOL
Anyway I need to build a power supply to provide current to anodize the parts for an AR-15 rifle. The average part is 7075-T6 AL and has about 24 sq in of surface.
I have been using a battery charger that provides 12VDC at about 6amps but it overloads and requires restarting frequently which requires constant attention and provides an uneven surface.
I have a transformer that will give me 17v or 20v with plenty of current capability along with 4 ea MJ11032 Darlington transistors on a big heat sink that I salvaged from an old battery backup unit.
Problem is that I don’t know how to design a working power supply with these components. I have or can get any other needed parts caps resistors etc.

Will somebody be kind enough to give me a simple schematic??


texts: A question about interpreting a supply's spec

texts:
How can I interpret this plot for [this][1] supply:
--to be edited--
Does it mean the max output current will decrease linearly with temperature but the voltage will remain the same ? What is meant by Load(%) here?


texts: How do interrupts work in embedded systems? I need a general view

texts:
I am trying to understand interrupts in embedded systems. Please correct  me where I am wrong.  Below is my understanding.
This could help me and other who are trying to understand interrupts.

Interrupts are the signals generated by a peripheral to request the microprocessor to perform a task. When an interrupt occurs, the CPU executes the current running instruction then stores the necessary stack pointer and program counter (PC) information somewhere in RAM allocated for the current function.

The PC is now vectored to the corresponding interrupt vector table index to execute ISR routine.

All interrupts are assigned individual enable bits which must be written logic one together with the global interrupt enable bit in the status register in order to enable the interrupt.

When an interrupt occurs, its interrupt flag is set and the corresponding ISR routine reads this flag inside them. For some peripherals these can be automatically cleared by reading the interrupt flag  bit and data register while for some peripherals we need to explicitly write a logic one to clear the interrupt flag bit.

If the corresponding interrupt flag bit is not cleared it cannot interrupt corresponding events again (for example, when interrupt A occurred and its interrupt flag is set until and unless you clear the interrupt flag the processor will not be notified about the next event from A,) make sure to read the necessary register before clearing them. Am I correct?

When an interrupt occurs, inside its ISR routine we can disable interrupt either by setting individual interrupt enable bit to zero or by setting global interrupt bit to zero. Doing this is not advised because this hinders nested interrupts from occurring thus some information will be lost.

When nested interrupts are enabled, a low priority can be preempted by a high priority interrupt.The ISR routine of the low priority interrupt will saved and high priority will get executed. If both are of same  priority the interrupt with lowest sub-priority will be executed.  Who assigns this sub-priority?

Maskable interrupts are the ones where we can disable the interrupt by writing instruction like setting the "Interrupt Enable" bit to zero.

Vectored interrupts are the ones where we already know the address to jump for the ISR, like the interrupt vector table with address and priority, for example the SPI, I2C, UART interrupt, timer.

What are non-vectored interrupts? I know that that we do not have a predefined address, but what is that suppose to mean? Can someone please give an example?


texts: A question about direct-coupled amplifier

texts:
A texts mentions that: "It is possible to have coupling circuits whose gain stays constant down to zero frequency - such circuits are called direct current coupled or 'DC coupled'"

Does that mean all the opamps are that sort of direct-coupled amplifiers?


texts: Thermostats outputs to GPIO then to Furnace

texts:
I have a question on how to safely connect and detect Thermostats outputs to Controller's GPIO inputs (RasPi and BeagleBone). I've been looking up a lot and most of the cases it is showing me how to connect GPIO outputs through relays then Thermostat inputs to make it a smart thermostats. I don't want that. What I'd like to have is:

Thermostat -> Controller -> Furnace.

So, I'm currently having a relay board between Controller and Furnace to control it. This should work. However, on the input side, I'm not sure how to connect thermostats output wires to the controller and detect which one is energized.

In other words, I'd like to know what ? in my high-level below needs to be so that I can connect them safely and know which thermostat call is called, knowing that thermostat output voltage will be 24VAC, and GPIO input can take 5VDC/3VDC, I believe. Please correct me if I'm wrong.

Thermostat -> ? -> Controller -> Relay board -> Furnace.

Thanks a lot guys.


texts: Battery Protection IC: How to ensure that even under-voltage batteries are allowed to be charged?

texts:
As I understand, the battery protection circuit isolates the battery from the battery connector if it detects undervoltage condition.

If this happens, how can the system ever charge the battery and make it usable?
I know that, the battery voltage would recover after sometime and it can be charged at that time, however,if the device is not plugged into a charger for a long time, then after several cycles of turning off and on, eventually, the battery would contain so little charge that it's voltage won't rise enough for the battery protection IC to enable it. So the battery would remain isolated behind the battery protection circuit and the system won't ever be able to charge it.


texts: 3.3v regulator problem when sharing power source with LED strip

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I have this circuit implemented on a prototype board.

The 12v power source is a 4A switching power supply. This powers the 12v LED strip, the 7805 regulator for the Arduino, and the IRU1015-33 3.3v regulator for the ESP8266.

The led strip is a 5 meters 12v 30leds/meter RGB, controlled by PWM from the arduino.

The problem: power on the 3.3v regulator output fluctuates depending on whether the LED strip is ON or OFF. When LEDs are full OFF (pwm 0% duty cycle) I get around 3.29v. When LEDs are ON (pwm 100% duty cycle) I get around 3.5v/3.6v, reaching the max input voltage for the ESP8266 module, wich is unsafe.

Wich ever duty cycle I put in between (say %50), I get almost the same signal variation on the 3.3v regulator output.
If I unplug the LED strip, the issue disappears and the regultar output stays around 3.3v.
If I unplug the ESP module, the problem stays the same. (In that case R8 would be the only load for the regulator)

Below are some oscilloscope captures I did.
CH1 is the output from the 3.3v regulator.
CH2 is signal between R3 and OK3, just for trigger and visualization purpouse.

PWM 0% duty cycle.

PWM 100% duty cycle.

PWM 40% duty cycle.

Strobe effect from 0% to 100% duty cycle. This one shows the voltage difference better.


texts: Electrical specifications for a solar tube light with rechargeable battery

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I was planning on simple project, the goal at hand is to make a tube light which has to run using a battery (max 4 hours during night) however I want the battery to be charged using solar panel,

These are the specifications

1)Tube light rated 10w which can run on 12Vdc
2)battery which I have chosen is 12v 7.5ah

My doubts

1) Is the battery overrated for the selected tube light?

2)i have 12V solar panel, I don't have its current specification it's voltage ranges from 8-14V based on light

3) I really don't have any idea regarding how to provide the charging support for the battery through solar panel since I don't have any constant Dc source to charge from any suggestion on this point would help me a lot

If battery is overrated for the task please suggest me a battery and charger suitable for the task.

Edit : I tested out the panels they are able to power 10W bulb full brightness during bright day.

Thank you


texts: Controlling voltage on source and drain of MOSFET

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I learned that MOSFET works by controlling the voltage on the Gate terminal. For NPN MOSFET as an example, when a voltage on the gate is high enough, it lets the current to flow through the MOSFET, and when a voltage is low, the MOSFET is off.

But what happens when a voltage changes on the source or drain terminal? I am studying the voltage level shifter and could not understand the logic behind it. When voltage on the source is high or low, what happens and why? What about when voltage on the drain is high or low?

Thanks!


texts: Estimating digital operation power consumption

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I am wondering if there are generally accepted methods of estimating the power consumption of digital operations as they are implemented in custom logic (ASIC). From this previous questions, it seems that people have done it with simulator tools once the RTL is written.

What I am looking for, however, is a back-of-the-evelope method along the lines of this previous question. Perhaps this is an attempt at taking the question a bit further. In my case I am interested to see if there is a way to estimate a modular operation by itself.

For example when calculating the mean of n 8-bit numbers I would like to say that the power cost of such an operation would be:

P_mean8 = n*P_add8 + P_divide8

I realize that:

Placement and routing (fanout, etc.) will play an important role in the final power number but I am not interested in getting bogged down in the details of such. I am more interested in getting a rough estimate assuming reasonably good practices.
Technology nodes (90nm vs. 12nm) will change the number but I am hoping there is a method that will take a few parameters from the technology node and scale the answer accordingly


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I'm %100 sure it's been asked before many times, but seriously can't find an answered question here.
let's say I have 5 logic outputs from a chip.
in order to OR them into a single Hi/Low signal, can I use a single 74hc32 chip as the diagram ?

My question is whether it's OK to feed an OR gate input of a chip through its own ouptut.
(thus kinda making a 5-input-single-output OR gate)