texts: Why VPP isn't 12V with safe resistor when a working microcontroller is inserted into this circuit?

texts:
I tested the whole functionality of my programmer circuit, and many things work, but some things don't.

It seems to erase the entire contents of an AT89C4051, but it does not successfully program the chip. In fact, it seems nothing is programmed at all.

This is the pseudocode I use for the programmer:

Clear data (Set address 378h to 0)
Reset counter and enable program mode and wait 100us (Set Control 37Ah to 6)
** At this point, Pin 1=0V which is expected
Raise VPP (Set Control 37Ah to 2)
** Expected 12V at pin 1 but only got 6.8V. Why? I don't know
Raise Step Reset (Set Control 37Ah to 3)
Wait until system ready
Add 10mS delay
Lower Step Reset (Set Control 37Ah to 2)
Wait until system ready
Reset count / lower VPP (Set Control 37Ah to 6)

And for each byte:

Set data (Set Control 378h to data)
Wait 100uS
Raise Step Reset (Set Control 37Ah to 1)
Wait until system ready
Wait 2mS
lower Step Reset (Set Control 37Ah to 0)
Wait until system ready
Repeat for remaining bytes

For reference, "raise step reset" means the 4017 IC pin is set to high and "lower step reset" means make reset pin low. Once it falls low, the programming enable will stay low for at least 1/2 the time defined by the 555 timer circuit then it will be raised then after the clock is pulsed then the system will be ready.

Just about everything works but there is

ONE MAJOR ISSUE

When I instructed the system to raise the VPP voltage, it does, but in a weird fashion.

The resistor I use between 12VDC and RST of the micro is 100K only because Atmel's datasheet states that the maximum programming current is 250uA. So by using 100K, I'm using 12VDC/100K=120uA.

So with no microcontroller connected, the operation is accurate. The meter shows very close to 12V. However, when I took a working microcontroller out of a working system and I inserted it into this circuit and measured the voltage after performing the exact same operations, I only get between 6 and 7V.

I looked at other circuits and I haven't seen others use 100K resistors as pull-ups. In fact, I found the pull-up resistor is only 2.7K in the following circuit at: http://www.oocities.org/dinceraydin/8051/index.html

My question is why would such a small resistor be used for programming when the manual clearly states that there is an upper limit to the current that can be provided for VPP?

Am I supposed to violate that spec to make the programmer work?

And for reference, this is my circuit:
and the diagonal line in the middle is part of an arrow, not wire.

UPDATE

I searched the Internet and found ANOTHER programmer circuit that uses a LOW VPP resistor (1K).

URL is here: http://students.uta.edu/rx/rxr5243/projects/prog/

Image is here: http://students.uta.edu/rx/rxr5243/projects/prog/schematic.gif


texts: Can I use a capacitive sensor to detect a person proximity without touch?

texts:
I only see uses of capacitive sensor to detect touch. But I wonder if I can calibrate a capacitive sensor to detect if a person is close enough, even if the person is not touching it.

I intend to use it with a RFID tag or a BLE to send information if there is a person close to it.

Update with more details: I want solve the problem of determining, cheaply, if a person is sitting on a chair. I already asked a question about this problem here: Can I use a RFID reader to check if there is an physical obstacle between it and the tag? through a particular way of solving this problem. Now I am asking about another way of solving it. It is not relevant if I will use a RFID tag or not. I understand there are multiple ways to solve the final problem, but now I am interested in knowing especifically if I can use a capacitive sensor to detect a person proximity without touch.


texts: Extract 5W low voltage power from 3000W high voltage source

texts:
I have a solarpanel array that generates 600V, 5A (3kW). I want to create a small electronic unit to measure the DC current and voltage and transmit this wireless. For this I have an electronic board with ADC's and transmitter. This board uses a maximum of 3.3V and 100mA. I want to use part of the power generated by the panels for this board.

I found some components like the LR8 from Supertex, but this is not supplying enough current and has a max of 400V. It seems like whatever I do to convert this voltage down to 3.3V, I loose a lot by heating of powertransistors or mosfets. As the board might be floating I wonder if there are more smart methods to power this board?

Any ideas would be very much appriciated!


texts: Removing resistor in Source Transformation method

texts:
I am trying to solve my simple circuit analysis question by using source transformation method.
In the solution, my teacher removes 125 Ohm and 10 Ohm from the circuit. He says it will not affect the power but these resistors affect the total resistor. Or i misunderstood him...
Could you please help?

Edit : In the question i need to find Power taken by 250V and 8 Amper.


texts:
Sorry in advance for the newbie question, but I can't seem to find a good answer. Recently, I've gotten into printed circuit boards and it is all still fairly new. I'm working towards creating a 4 layer pcb and I'm curious common practice for layer stack up. I've seen some places that use the outer layers as signal layers and internal two layers as GND and VCC and vice versa other places.

Is there any  stack up for a four layer board (or any amount of layers for that matter) that is particularity advantageous?

Also from previous research it seems that having both a GND and VCC plane creates a small amount of capacitance, why is this useful?


texts: Amplification of signal in a circuit. Is my calculation ok?

texts:
I want to find the amplification, $$U_{out}/U_{in}$$ of the pictured circuit. My electronics knowledge is very basic, but I tried to solve this using the ground node method, with the bottom of the circuit being grounded. I noticed that

$$V_y=U_{out}$$
$$V_1=U_{in}-V_x$$

Then I write equations for the node voltages (I switched resistances to conductances for clarity):

$$V_x(G_E +g_{CE}+g_{be})-V_y (g_{CE}) = gV_1 = gU_{in}-gV_x$$
$$V_y (g_{CE}+G_C)-V_x (g_{CE})=-gV_1=gV_x-gU_{in}$$

Adding the two equations I got:

$$V_x (G_E+g_{be})=-V_y (G_C) \implies V_x=-\frac{G_C}{G_E +g_{be}}V_y$$

Now from the first equation, after substituting:

$$V_y \frac{G_C (G_E+g_{CE}+g_{be})}{g_{be}+G_E} =-gU_{in}$$

$$\frac{V_y}{U_{in}}=\frac{U_{out}}{U_{in}}=-g\frac{ g_{be}+G_E }{G_C (G_E+g_{CE}+g_{be})}$$

Is this solution correct?

I also want to find the input resistance, but here I'm completely out of ideas.

simulate this circuit – Schematic created using CircuitLab


texts: Voltage and Current Sensor for Alternating Current

texts:
I want to measure the voltage and current of a AC powered device using a micro controller like Arduino. I am unable to find it.(I am new to these).
Is there a circuit or sensor which isolates from the AC and able to measure voltage and current with voltage and current values accurately.
I have a supply of 240V and the device consumes around 10A


texts: I am studying Wien Bridge Oscillator. The part I do not understand is how the other frequencies die out.  For example, let us say initial disturbance was not of the resonant frequency but a higher frequency, then what mechanism ensures it dies out and similarly what is the explanation for lower frequency?


texts:
I'm doing a bit of research into some audio graphic equalizers and the following questions have come to mind.

Typically, what is the Q-factor for a standard audio graphic EQ/band? For example, if one slider is labelled 800Hz, what range of frequencies will that filter pass (let's say the cutoff is the cutoff frequency)?

How much overlap is there between filters/bands? For example, does one simply match the high end of the bandwidth for one filter/band, with the low end of the bandwidth of the next filter/band (i.e. matching cutoff frequencies)?


texts: Identifying unknown components in transformerless power supply

texts:
So my dad found one of these voltage converters lying around.

I was quite curious what components it had as it is very lightweight (transformerless) and boasts a good 1600W @ 110vac (14.5A) on the output.

I've included a very rough schematic I drew out:

The two circled components are the ones I'm having trouble identifying.

The first component on first glance appears to be a zener diode, however it only has a single mark in the middle and no mark on either side (hence my confusion)

The second (at the top of the schematic) measured 220ohms across it. Is this just a very high watt resistor or does it serve another purpose? It appears to just be a block of carbon.

I'm very curious also if this circuit can actually handle the 1600W it states. I know the triac is rated for 15A (with a very sizable heat sink) but it's the other components that trouble me. Also what kind of power supply is this? A capacitor supply? I thought most of these would only handle a few hundred mA.

First post here so thanks for any responses in advance.


texts: Capacitive sensor - How to activate with a portable device

texts: I'd like to activate a capacitive sensor - a smartphone touch screen for instance - with an electronic device - say an Arduino board. Basically I'd like to reproduce this instructable, but with one more condition: I want my Arduino to be powered on battery, so with no GND. Do you think this is possible?


texts: How to power a Raspberry Pi with a flight controller

texts:
I am making an autonomous quadcopter and I need Raspberry Pi on board to implement image processing. The issue is that I have a 4in1 ESC which comes with only one UBEC (Universal Battery Elimination Circuit) to power the flight controller, I would need another 5V to power Raspberry Pi.

The flight controller that I am using is an All in One Pro, and the ESC is the Quattro 4in1 30A ESC.

As the flight controller is an Arduino board with sensors, I think it should have a 5V output that could power the Raspberry Pi board.

The other option is to get an UBEC and connect the battery to the 4in1 ESC and the UBEC in parallel. Then the ESC goes to the motors and flight controller and the UBEC to the Raspberry Pi board.

Any suggestions?


texts: From microcontrollers to microprocessors [Embedded Devices]

texts:
I was told by some developer that embedded controllers are task specific devices that requires low latency which processor based devices can't offer due to OS overhead.

So I would like to first of all confirm the correctness of this statement.

Secondly, what is the "level of sophistication" which mandates use of processors with an operating system. I know this can be broad as it is difficult to define "level of sophistication" so a specific example or two might help.

Inorder to not get penalized, I can narrow it down by asking:
Can the basics of functionality such as web surfing device be designed purely using microcontrollers without OS?
And since web surfing device must take user input, communicate over the internet, output to the display, output to the audio etc, can such level of sophistication be achieved by writing mere firmwares and using micro controllers? (barebone programming)


texts: Figure of merit of Operational amplifier

texts: How can I measure FOM(figure of merit) of an operational amplifier? There are so many parameters, how can I decide which formula to use while calculating FOM?


texts:
I need clarification regarding comparators with internal Hysteresis.

I have a comparator with internal Hysteresis “X” mv and I am using external feedback resistors to create a hysteresis of “Y” mv.

Will the total hysteresis be “X+Y” mv?


texts:
Following on from my previous questions, I'm still trying to get this USB hub to work.  My circuit now looks like this:

Note that this is only providing USB access to other on-board devices and so I'm ignoring the downstream bus power pins (for now, anyway).

For now I've hand-soldered a 1.5k resistor between USBDM and 3.3V (the R? in the diagram above - note that TSTMODE is tied to earth for 6MHz operation, though I've also tried connecting this resistor to USBDP).  Now when I plug the device into a USB port, I see a bunch of signalling on USBDM (and I assume USBDP, though I don't have easy access to get a scope probe on it) but the hub still doesn't appear in the USB device enumeration on the host (ie the output of lsusb).  I've captured this signalling on a scope but can't for the life of me figure out how to get it off the scope in anything other than RCD format, whatever that is.  At any rate, the signal levels all look good and the corners are all nice and clean, no noticeable ringing etc.

As far as I can tell, the hub device should be supported by the Linux kernel without further configuration.

Can anyone point me to what I'm doing wrong?

Edit:  Here's the RCD file.  I have no practical way of looking at this (UltraScope won't install correctly on Win10 and won't display an RCD trace under Wine) so I've no real idea how useful it is.

Edit 2:  Here's a relevant-looking snippet from dmesg:

[91417.181536] usb 1-1.4: new low-speed USB device number 65 using dwc_otg
[91417.281536] usb 1-1.4: device descriptor read/64, error -32
[91417.501465] usb 1-1.4: device descriptor read/64, error -32
[91417.721464] usb 1-1.4: new low-speed USB device number 66 using dwc_otg
[91417.821544] usb 1-1.4: device descriptor read/64, error -32
[91418.041534] usb 1-1.4: device descriptor read/64, error -32
[91418.161562] usb 1-1-port4: attempt power cycle
[91418.821546] usb 1-1.4: new low-speed USB device number 67 using dwc_otg
[91419.261548] usb 1-1.4: device not accepting address 67, error -32
[91419.361551] usb 1-1.4: new low-speed USB device number 68 using dwc_otg
[91419.801527] usb 1-1.4: device not accepting address 68, error -32
[91419.801667] usb 1-1-port4: unable to enumerate USB device

I'm still a little confused over what speed I should be selecting for this thing.  The datasheet talks about 6MHz and 48MHz mode which I had mentally correlated with USB Low- and Full-Speed modes - but now I look at it again, I think this is only talking about the clock source for the device and in either mode it's a USB Full-Speed device - is that right?  In which case I should switch R? back to the D+ line.


texts: What kind of two-pin connector is just a little smaller than jack 3.5?

texts:
I found an old DIY amplifier that I would like to use, but I ran into a problem: I don't know what kind of connector it has.
I know for sure that this device is an amplifier, since I once used it and I even vaguely remember the appearance of the connector (it looked like a jack), but about 10 years have passed, and I can’t remember more.
I remembered that the connectors for this amplifier were short (like jack 2.5) and only with 2 pins (TS). Unfortunately, I don’t have 2.5 connectors on my hands, but it looks like they need more than 2.5 sizes. The 3.5 connector is only slightly larger than the connector on amplifer.
I was surprised by the connectors on the front panel - they are wider than the 3.5 jack (it dangles there), besides, they are too shallow for 3.5 and do not fix the plug. I don't need them, but it would be interesting to find out about them too.
Does anyone have any suggestions what kind of connectors there might be?


texts: Atmel ATxmega128A identical boards - one fails to enter programming mode

texts:
I have two identical boards both equipped with ATxmega128A. I am using Atmel-ICE for programming using PDI Interface.

The first board, I can read the device signature without any issues.
On the second board, the error "unable to enter programming mode" appears.

After some trial and error, I changed the PDI Clock of Atmel ICE from default 4MHz to 1MHz. Now I am able to read the signature of both devices.

Question: How is it possible that 100% identical boards where one works with 4MHz PDI Clock and the other one only with 1MHz PDI clock?


texts: How to calculate temperature of busbar when current flowing through it is 600A for atleast 10mins?

texts:
I am new to the bus bar concept. Can anyone please guide me how to calculate the temperature of copper bus bar when current flowing through it is 600A for 10mins.

Should it be this way:
Power, P = IlIlR ; R = p*l/A
Can you guide me for the rest???

Thanks in advance!!!


texts:
I am designing a damping resistor [minimum load of SMPS] in parallel to output capacitor of LC filter.

SMPS specs:
1. Vout: 200 V
2. Iout [Max]: 2 A
3. PWM frequency: 50 kHz

Output filter specs:
1. L1: 680 uH
2. C1: 30 uF

Resistor value was calculated using R_damp = (Q*(Sqrt(L/C)))
With Q = 1, R_damp = 4.76 ohm.

This can set SMPS always in Over current protection state. Increasing the resistance makes the filter under damped. One solution I figured out was to place the R_damp in series with C_damp = (10*C). Here the Voltage across R_damp will not be Vout and hence lesser or no current as C_damp is open to DC voltage : Vout. So here the SMPS should not reach over current fault. Am I right or is there any way people go about damping SMPS LC filter?

simulate this circuit – Schematic created using CircuitLab


texts: Calculate the frequency corresponding to a given current or power attenuation in an LRC circuit

texts:
For a series LRC circuit, I'm trying to calculate the frequency corresponding to a given current (or power) attenuation to either side of the resonance frequency peak according to the formula for current:
$$ I = \frac {V_{rms}}{\sqrt{R^2 + 2\pi FL - \frac {1}{(2\pi FC)^2 }}} $$
Is there a way to factor out / isolate F?  I can't find anything beyond the usual 3dB spec.


texts: Signal conditioning of conductive polymer

texts: I have a conductive elastic polymer which gives the resistance change of 800 Kohm with the input strain of 250%. and also gives linear response when the force is applied. I wanted to have a signal conditioning circuit which can measure the force range in the range of 0 to 45 gm. how can i start designing the signal conditioning.? Thank You.


texts:
Is there some way to display package type of part in Eagle schematic. Something like name and value field but containing package information. It can be name of package associated with schematic symbol or empty field where something can be written manually.

How do I display package type in an Eagle Schematic?


texts: Generate high speed data using GTX transceiver of Kintex-7 FPGA board

texts:
I want to use Genesys-2 FPGA board as a BER tester for transceiver circuits. I am using IBERT IP core available in Vivado for it. Genesys-2 has an FMC connector to provide output for which I am using SMA-FMC-LVDS  of Hightech Global to convert the data from FMC to SMA. Initially, I am connecting transmitter and receiver in loopback just for verification.

The problem is:
1. In loopback connection, in Vivado I am unable to see any transmission. It is only displaying 0Gbps.
2. Previously I have used different SMA-FMC board for which transmission was proper and I was able to measure the BER. By this, it is clear that there is no problem with the code.
3. In the SMA-FMC-LVDS a place holder is provided for an external oscillator. Do I need to solder this oscillator for proper transmission?

I can not find any supporting document for the configuration of SMA-FMC-LVDS.


texts: PFC boost converter is not stepping up the voltage

texts:
I am making a PFC circuit for AC-DC converter. I am facing a weird issue. As per my design the output of the circuit should be 390VDC, but I am getting 311VDCrms with ringing (overshoot 360V, undershoot 270V).

Here is my circuit (the red marks are the only differences between TI's circuit and my circuit, like, in TI circuit inductor is 2mH and in mine it is 0.56mH).

And this is the output waveform.

Here it is zoomed

When I turned off Vcc to the controller IC, the output voltage of the circuit  is also 311VDC !!!!!

Here is the input of pin 4 in oscilloscope

Here is output of pin 5 in oscilloscope

Here is input of pin 3 in oscilloscope

I am fully confused on what is happening. Please help me !!!!


texts: How can I operate two ASK RF Transmitter modules(433 MHz) simultaneously without jamming each other?

texts:
Transmitting using this transmitter seems to jam many wireless devices (possibly using the same frequency) like car keyless entry remotes, garage door openers etc. Moreover, two such transmitters cannot be used simultaneously as they jam each other and the receiver gets no signal from either. One workaround is to use an oscillator to transmit discountinously (a short burst every few seconds). But I was wondering if there is a way to solve the jamming issue and transmit signals from both the transmitters simultaneously. The receiver is common for both the transmitters (assigned different addresses using HT12E) and hence signal from just one transmitter is used at any given point of time.

Data sheet(not of the exact product but is similar)
https://electrosome.com/wp-content/uploads/2014/10/MO_SAWR.pdf


texts:
I'm currently working in a charity shop.

We have a range of hi-fi units, radios, CD players etc.

We also have a range of speakers to go with them.  Some are marked with their nominal impedance, others are not.

I am generally able to determine the recommended speaker impedance range for a particular hi-fi either because it is marked on the unit or I can find the specification online from the make and model number.

In many cases however there are no markings on the speaker to help me.  These speaker units are as supplied with a particular hi-fi so may contain more than one raw speaker together with associated internal crossover circuitry.  In some cases I know the manufacturer of the hi-fi as I have say a 'Sony' label on the speaker unit but no indication which model it was intended for.

Is there a simple way for me to measure this?  I am assuming it is not as simple as the DC resistance.

I can imagine placing a resistor in series with the loudspeaker and a small, say 1 volt, signal generator across the pair by measuring the, true AC rms, voltage either side of the resistor I can calculate the impedance.  Is this the best option or is there a simpler one?

If this is the best option what frequency range would I need to measure over and which figure should I take?

The intention is that the charity shop can sell a second hand system with suitable speakers even if not the ones that were originally part of the system.


texts: Confusion with Applications section of components

texts:
Im recommended to install a 10000uF Aluminium Electrolytic capacitor for a 72 DC-link of an inverter for regenerative purpose. When it comes to details, one manufacturer mentions "inverter" in applications the other mentions general industrial electronics.

Is there any significant difference between these two capacitors.

Cap 1
Cap 2

Since it is based on marketing I couldn't find a way to justify one capacitor or the other.

Which parameters should I check for such application?


texts: I just bought this awesome H2 Hummer RC for $2 at a garage sale (the battery alone that was inside is worth about $100.). The motor works fine and the car is in excellent shape but it did not come with a remote to control the car. Is it possible to just buy any remote to control the car? How would I get it to work with this hummer?


texts: Is it safe to directly use the output of the battery cell pack inside of a portable charger?

texts:
I have this battery: https://www.amazon.com/gp/product/B07SWBS55F/ref=ppx_yo_dt_b_asin_title_o09_s01?ie=UTF8&psc=1 which has 156W of output when all 3 output ports are added.

To avoid unnecessary conversions, I'd like to have 1 output of ~150W, so I opened it up and there's a battery pack containing the 18650 cells in 7s2d and a small PCB that all the original in/outputs are attached to, so the PCB is likely for regulating charging, stepping down outputs to the manufacturer's provided outputs, & keeping track of battery charge level. I wanted to keep the PCB for USB power out/charging/battery level purposes, but add a 3rd output that would simply be the 2 leads from the battery cell itself and bypassing that PCB entirely for a 24-25V output that would let me draw current limited only to the cells' actual rating. It'd also mean I eliminate another power conversion step & its associated lost efficiency.

Is this safe to use the battery cell output directly or is there any safety circuit I missed that would have to be added? (or is this going to severely reduce the life of the battery/how could I avoid that) Could I use the battery from my new port while it's being charged? Could I use both my new port as well as an output on the existing PCB (for example, plugging a phone in to the original USB output and using the new raw output simultaneously)? Would the charge indicator still be accurate?


texts: How to parallel 2032 coin battery without removing the dead one?

texts:
I have device that run with 2032 coin battery but right now battery is dead/empty I want to know how to parallel new one without remove the empty one to avoid wipe out data. or a way to charge the empty non rechargeable coin battery without remove it from it socket.
Thanks for your reply
NB:  it's my first question hope to not be kicked after my first question :)


texts:
Is there a fuse alloy that would have the same springiness as this

except with a little wire that comes out and that plugs into something, so that it could be machined and pressed from one single sheet metal, so that the spring and the fuse are both pressed out of the same metal, to save costs?

i just want to machine a springy clip and fuse from the same metal sheet because it would be Sooo much easier to make than getting a company to make super robotic parts with weldings etc.


texts: Which pins should I use to connect a watch crystal for powering a low frequency crystal oscillator in ATmega328p?

texts:
If I want use a watch crystal(32KHz) with the low frequency crystal oscillator of an ATmega328p, which pin should I connect the crystal to?
Should I connect the crystal to XTAL1,XTAL2 pins of ATmega328p, or should I connect the crystal to TOSC1,TOSC2** pins of ATmega328p?


texts: Can more than one memory device transmit on the data bus at once?

texts: I know that in general only one device can transmit over the bus at once, but if they are all memory devices, can they act as one? I have four 256x8 chips, which I think means that I have 256 cells which can store 8 bits (1 byte). So how would I express the total memory? 256 cells * 4 = 1024 cells, but I am not sure whether or not the answer is 1024x8 or 1024x32. I am leaning towards 1024x8 because I don't think that more than one device can trasmit over the data bus at once, but I am not certain now that I know that all the devices are memory devices.


texts: Class A power amplifier, how to calculate base voltage after removing collector load

texts:
In the following circuit:

I calculated the base voltage by Vb = R2/(R1+R2)  Vcc  [stiffed voltage divider] , but then when I'm asked to calculate the total power from the power supply when we remove the load, the base voltage changes.

My question is why does the base voltage change after removing R_L and how do I calculate it? This is how the solution calculates it and this is what it says:

I don't understand how Thevnin's theorm is used here and why is it even used


texts: Why are lithium batteries stored at 50% voltage and not a lower voltage?

texts:
I understand that a higher voltage causes more degradation of the material in the cell, but I'm curious as to why the typical storage voltage is not lower than 50%.

I've always assumed that the lower the voltage, the less material degradation, but that starting a storage cycle with a voltage too low runs the risk of dropping the voltage to a point where the cell cannot be recharged, but I haven't been able to find a definitive reference for this.


texts: Interfacing Raspberry Pi to GE NetworX NX-8V2

texts:
Much like this question, I am trying to interface a Raspberry Pi 3 Model B to an alarm system, but this time is is a GE NetworX NX-8V2. I have snooped on the control box with a voltmeter and it looks like when a sensor is tripped (i.e. a door is open, a motion detector detects motion) the corresponding pin goes from 0V to about 0.3V. What I would like to do is monitor the pins with my RPi, so I figure that the input voltages to the RPi will need to range from 0V to 3.3V in order to work with the GPIO pins.

However, I have a problem.

My idea is to use an op amp (I have a couple of LM2902N's lying around) to multiply the voltage. Using the op amp as a non-inverting amplifier, and choosing my resistors as shown in the schematic below, I should see a gain of 11, which should give Output = V0 * 11. When I simulate the circuit, it works exactly as I intend. However, when I implement the circuit on a breadboard the output stays at a constant 3.9V, regardless of if I implement the circuit as designed or disconnect the V0 input. (Another data point: when I tested with V1 set to 3.3V but everything else the same, the Output stayed at a constant 2.1V)

simulate this circuit – Schematic created using CircuitLab

Any ideas on why my circuit is behaving like this? (Or if you have another way of solving the problem, that would help too. Another idea I've considered is to implement a voltage comparator with Vref at 0.15V)


texts:
I am new to the forum and hope you could put me in the right direction.

When designing a J1939 harness what is the physical layer constraints, if multiple ECU's need to be connected? Is there any documentation to help with this.

I am aware of the following, so please correct or add if I missed anything:

The Backbone of the J1939 bus should not be longer than 40m.
2x 120ohm resistor need to be used  on the bus ends
Stub length from the backbone to ECU should not be longer than 0,3m
There is no official wiring colour that need to be used,although Green(CAN L) and Yellow (CAN H) seem to be the most common used?

If referring to Loop in Loop out each module, what is meant by this (Drawing perhaps)? I understand this is a better way of connecting if it is practically possible.

Thank you in advance for all the comments.


texts: Driving single coil latching relays with logic buffer IC's

texts:
Hi I am planning to use 6 latching relays in my new project.The relays that iam planning to use are 5V,20mA rated " 6-1462037-0" from TE Connectivity Potter & Brumfield Relays

I have a 6.5V circuit currently available in the circuit and was seeing discussions on driving single coil latching relays with logic buffers. Can someone share an application circuit for same and tell me what are the things to take care while designing the same


texts: 10k Resistor Pull Up/Down Standard for 74 series chips

texts:
I've been having some issues lately with the usage of 10k ohm resistors as pull down resistors for 74ls series chips. Most people seem to choose 10k resistors as their default pull up/down value but I've found that the pins seem to float a little anyway when trying to pull down on the TTL 74ls series chips. My solution was to switch to a smaller value that I had on hand such as 1.1k ohm. My question is why 10k is the default assumed by many making electronics projects, and why might I be having a problem with this value that is eliminated by using a lower resistance value?

I haven't been playing with hc series much lately so I am unaware if the problem is particular to the 74ls series.

Edit: I also experienced this problem with a 28C16E EEPROM chip and solved it with 1.1k instead of 10k. Could this be related to noise in my power supply setup (c.M.T-305D set to ~5V DC)?

Edit: I notice people seem to have interpreted the pull down resistors as being used when the input is unused (could be tied directly to ground for 74ls or 74hc). This was not what I meant. The case for these pull down resistors is with the use of dip switches or I/O with a 5V bus.


texts:
I want to program an ATmega over JTAG, but I would like to build the JTAG programmer myself.
Is it possible to program an ATmega128A by constructing a JTAG programmer similar to this?

It uses an FT232R FTDI chip from one of these boards:

Connected to a JTAG header like this:

If this is possible, what software would I use to program with?


texts: Why do smoke detectors run off 9v batteries?

texts: Is there a component that requires a higher voltage? Wouldn't they last longer on AA/AAA batteries?


texts: Converting 5v to 3.3V for GPS purpose while keeping noise at the lowest

texts:
I'm trying to create a very simple module that consist in powering a GPS ublox - NEO-M8U - with a micro USB & using an active antenna.

Later on, I will add more features but I just want to make sure I'm doing things the right way by keeping the noise at the lowest.

Here's what I did using information I found mainly on stackexchange.

I decided to go only with a 10uf capacitor for the Vin. Some people are in using 22uf, 100nf & 10uf in parallel. Would that make sense to use more capacitors on this side on the circuit ?

For the GPS, I went with this :

I'm just not sure about the inductor. The problem I have is that I want my card to be directly assembled by the PCB supplier and they did not have the 27nh recommanded by the GPS manufacturer. Also I really don't know how to choose such inductor. Do people have good practices for that ?

My last question is for the board design. Should I have the biggest capacitor the closest to Vin ?


texts:
I am not sure how to ask this question. Hopefully, I will edit it to make better sense as we go.

I have an image with 10 μm wide black and white stripes and I project it onto the imager, with 1000 pixels, 10 μm square each. Do I have to do image magnification in order to achieve 10 μm resolution. That is, being able to resolve black and white stripes?

My speculation:

I fill like if the line centers will be 'in phase' with the pixel centers, I will be able to resolve them. However, if the line centers will fall between the pixels, each line will take up two pixels, meaning that I will not resolve them.

I can not change the size of the pixels, but I can change the magnification of the image/stripes. Do I follow the Nyquist principle? In this case, if I understand right, the lines should be at least twice wider than the pixel's width. So, to make it happen, I must magnify the image 2x. Do I understand it right?


texts:
I am a bit confused of The relation betweeen the parameters mentioned above.
According to the below formula, speed is inversely proportional to Torque as:
T=HPx9549/Rpm
But i have been taught in my college that speed is directly proportional to torque because to rotate an object at high speed we need more torque(POWER).
Coperation is needed.


texts: Does a low-quality UPS affect its battery life?

texts:
People say that "local" UPSes (uninterruptable power supplies) reduce the life of their batteries while other, "branded" UPSes are better and do not affect the battery life.

I have noticed that a battery with a "local" UPS lasts only 2 years, but batteries with "branded" UPSes (in which good technology is used) last 2-and-a-half to 3 years.

My question is: A UPS consists of an inverter and charger (along with other things I have not mentioned), so how can a bad UPS affect its battery life?


texts: Sensing power supply - sensing after the on/off switch

texts:
I have a sensing power supply powering a custom build LED light for video. There is an on/off switch after the sensing lines and everything works well. The setup looks like this:

However I'd like to sense the voltage drop after the switch.
As what I have read in the PSU manuals, this configuration will cause current to flow throught the sensing lines when the switch is open and damage the PSU's resistors.

My question is, can the configuration work with a diode placed on the +SENS line to stop current when the switch is open? Like this:


texts:
I would like to simulate the ZVS Synchronous rectification buck converter, I know if I operate in ZVS I need to change the switching frequency of the buck converter.
Here are my questions:

How to model the variable frequency of buck converter? I think the small-signal model is not the same as the constant frequency buck converter.

How to implement the variable frequency control in PSIM or SIMPLIS? I would like to know how to build the control stage, I only can design the control stage in constant frequency.

Do you have some material you can suggest to me to read?


texts: Can I put a zener diode *before* PTC to protect the supply?

texts:
I'm designing a small module that takes power from USB and provides it to a breadboard for prototyping. My target audience will just be hobbyists so I want to include some protection. I'm more concerned about protecting the USB supply from mistakes made whilst prototyping rather than protecting the board from faulty supplies.

I'll be including a PTC resettable fuse to protect the USB supply from shorts and over overloads. One thing I am concerned about is when a higher voltage (say 12v) is accidentally connected to the 5v rail, I don't want this to be backfed to the computer or other device that is providing the 5v over USB.

Normal use of a zener diode would be to be place it after the PTC fuse, however I am thinking for my circuit it might be better to place it before the fuse. This way if a user was to accidentally connect 12v to the 5v line, it would first flow through the PTC and then the zener, hopefully tripping the PTC.

Is my thinking here correct?


texts: With no external resistors, is it possible to calculate drain voltage of a MOSFET with known values for Vg, Vs, Vb, and Ids?


texts:
Is it a good practice to make a separate RF ground for a part of the board consisting of the RF module and antenna connector?

The PCB is 4 layer board, with 2 internal planes. The top and bottom layer ground pours around the RF parts are completely separated from the digital ground pour (rest of the board). The GND internal plane is connected to the rest of the plane in a single slot, and that is the only connection between RF ground and digital ground.


texts: PNP and NPN transistor characteristics for this project (see link inside for schematic)

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I'm working on this project

https://github.com/diyhue/Devices/tree/master/HueDimmerSwitch

I would ask which characteristics I need to keep in consideration to choose that two NPN and PNP transistors?

Are these one a good choice?

NPN: S8050 J3Y
PNP: S8550 2TY

EDIT:
I forgot to mention I need transistors in SMD package


texts: I need to create a planar inductor with a specific value of 28 nH on a 4-layer PCB. How do I determine the proper trace geometry?

texts:
I am using a Linear Technologies LT-1534 part an need to create a planar PCB surface inductor with the specific value of 28nH; i.e., the inductor will be a copper trace on the PC boards Top Surface to have a value equal to a discrete inductive component, that value to equal 28 nano Henries +/- 10%.

What formula should I use to calculate the Planar Inductor's geometry that will enable me to achieve this specific value?

The PCB's layer stack up is a 4-layer board with Top & Bottom Signal Layers, Components on Top only, with Ground Plane and Power(s) Plane on Layers 2 & 3 respectively.

The system is powered by a LiPo battery.

I have designed Printed wiring boards for many years (over 30) and have done Multi-layer Planar Transformers before, but have not had such a specific inductor value on a single layer come up as a requirement before and am a little stumped as to where to start.

The circuit goal is to design a local RCL filter for the LT1534, where the capacitive and resistive elements are comprised of discrete passive leaded components, but because of size constraints as well as the small value of inductance required, the design engineer feels that the goal would be better achieved using a Planar inductor, rather than a discrete, even surface-mount component element.

The target PCB material is FR4@0.063" thickness, one-ounce clad to between 1 1/2-2 oz finished, to be determined by other targeted trace impedances and controlled impedance transmission line requirements.

Please let me know if more specific information is required to make an educated reply, or if a schematic of the sub-circuit which contains the inductor in question is needed to make a proper assessment of the formulas required for the PCB inductance to be specified.


texts: How to calculate the power dissipation in a transistor?

texts:
Consider this simple sketch of a circuit, a current source:

I'm not sure how to calculate the power dissipation across the transistor.

I'm taking a class in electronics and have the following equation in my notes (not sure if it helps):

$$P = P_{CE} + P_{BE} + P_{base-resistor}$$

So the power dissipation is the power dissipation across the collector and emitter, the power dissipation across the base and emitter and a mystery factor \$P_{base-resistor}\$. Note that the β of the transistor in this example was set to 50.

I'm quite confused overall and the many questions here on transistors have been very helpful.


texts: Using a MOSFET to generate a particular voltage

texts: So ,i wish to cycle 1.4v and 5v through a sensor for 60seconds each. I have a mosfet STP90NF03L with Vgs(th)=1v (min).I am using arduino's analogWrite(pinnumber,value)  to get 1.4 v output.. but i want the current to be at a higher limit then 40mA (arduino can source max 40mA).Is it possible to achieve that using the mosfet with arduino pin output connected to gate of the mosfet ?


texts: Is it common practice to connect power supply to a DB9?

texts:
I got a project where many sensors which uses CAN were connected to a DB9.

And sensor power (24V and GND) too. I want to connect the DB9 terminal to power however how can I do it in a safe way? If I connect using tiny wires like the ones I use with Arduino might burn.

Above image was Lidar sensor which I had to buy the correct cable to work and worked. Now using Radar (Delphi ESR 2.5 24V) there is only one terminal and power input goes to a DB9 (like the one in the image)

Does anybody have ideas? Estimated current is around 900 mA.

Please check two last pictures for terminal information


texts: Choosing the right parameters for a Pulse wave simulation in a CAD schematic

texts:
I'm trying to choose the right parameters in the simulation in order for the output to show a square wave of gain C1/C2 = 2V

Anyone know what I'm doing wrong? Thanks.


texts: When and how does a buck converter behave in a boost converter mode?

texts:
My question is with reference to this answer for this previous question.
The answer states that a buck converter will behave in a boost mode for some cycles during light load or no load condition.
Can someone help me with the exact cycle of operation and why does it happen?


texts: How do I pre-tune and verify a receiver frontend?

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In the design and implementation of an RF receiver, I'd like to build and verify it stage by stage, with particular attention to impedance matching, noise figure and gain.

If I had access to a professional RF lab, I'd be using network analyzers, VSWR meters, spectrum analyzers, an RF-anechoic chamber and a reference transmitter, but I have none of those things, nor the desire to burn a few hundred thousand dollars to get them.

I'd like to plan a methodology that can give me some assurance that the receiver I make is going to work, and give me some idea of the minimum receivable signal. This is far before the stage where I'm able to say what exact gain, noise figure, selectivity, etc. the receiver will need. If it picks up anything at all, I'd be happy (for the first iteration).

Let's assume that I have a basic DMM, and a function generator and scope that are both capable of 3-15 MHz, the band the receiver will use.

Perhaps a methodology could be:

Simulate the antenna and tuning network to verify that they are expected to work. My concern here is that antenna predicted vs. actual impedance will probably vary. The formula I have does not account for inter-winding capacitance or wire resistance.
Simulate again, but add the equivalent circuit of an oscilloscope and lead+probe. This is expected to add capacitance (lower resonance frequency) and resistance (lower Q).
Build the antenna (in this case a manually wound AM air core loop antenna)
Connect the oscilloscope to the antenna
Place generator cable around core of antenna for inductive coupling
Short leads of generator cable to each other
Set the generator frequency to 3.33 MHz, the first station I'm interested in receiving
Starting at 0, increase amplitude of generator until signal is seen on scope
Add tuning cap to antenna leads
Verify that signal as seen on oscilloscope peaks when cap is about in centre of designed adjustment range
If previous step shows a heavily lopsided response, i.e. tuning cap is unable to get antenna to resonate, adjust generator frequency until resonance is seen, and calculate backwards to infer antenna impedance and required tuning network

For a budget/hobbyist design, does this methodology make sense?


texts: Simulating matching op-amp input impedance with offsets

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I have a current source with RC filter at the input of an LM324 op-amp configured as a buffer. The Input Biasing Current is 45nA and the Offset Current is 5nA for the LM324.The input resistor is 750k and normally a 750k resistor in the feedback loop would balance the inputs. With the output connected directly to IN- there is about a 30mV difference between the input and the output, where the input is about 400mV. However to get the circuit to provide a gain of 1 I doubled the feedback resistor to 1.5Meg. The result is much better and the output error is much smaller. Why is it that double the resistor was needed here and not 750K?

Also I am trying to simulate this behavior in LTSpice using the circuit below and have included the offset input currents. However a direct connection from output to IN- gives a gain of 1 and does not indicate real life results. is there a better way to model this?

Thanks.

Edit 1:

Meter at IN+ creating a voltage divider with R2 and creating a voltage drop. When the same meter is used to measure the output the voltage divider disappears. Tried with 2 meters simultaneously and input and output were closer. Still has the voltage drop, but they are the same.


texts:
In a CB Amplifier, the Base is common to both Input and Output. Why is Input applied at the Collector and Output at the Emitter?

Could it have been the opposite?

Similarly, for CC and CE amplifiers why are the chosen Input and Output terminals selected?


texts: Can I use sfp+ transceivers to interconnect PCIe x1 lane?

texts:
This is interesting because, sfp+ offers an inexpensive way to use optics to connect two PCIe x1 devices.  But I do not know enough about sfp+ to know if I can simply connect up pcie lanes on a motherboard to a sfp+ transceiver card.

I understand that I shall not have sideband signal access.  But I can live with that as I do not need to power the device via PCIe.

Thank you.
Best regards,


texts: MCP73834 disintegrates after a couple of hours

texts:
For my first attempt at Li-Po charging I chose the MCP73834-FCI/UN for availability, it has an output current of 1A. I set it up the example circuit in the datasheet and used an 6Ah battery to test it. I had it on my bench while working, monitoring the output every half hour or so and everything was looking good. After about 3 hours it just went up in smoke for no particular reason, the battery was at room temperature though not fully charged (4.04V).

The only thing I can think is that these units weren't designed to operate for such a long time. I disabled the charge timer on purpose since it would take a fairly long time to charge a 6Ah battery. Should I be taking a different approach when working with batteries of this capacity?

What input voltage are you using? -> 5V

Are you using a heat sink? -> 2 Layer FR4

What temperature did it reach? -> Battery: 25C, MCP73834: Wasn't monitoring but the charge rate was slower than expected so probably spend a lot of time in thermal shutdown.

What charge current are you using? -> 1A

Are you observing all data sheet requirements? -> Guessing No...


texts: Home-automation standard for custom devices

texts:
I'm willing to build my own home-automation system (at least partially). I haven't chosen the protocol yet.
My goal is to make home-automation devices that would be compatible with controllers/software and other devices on the market.

For example, I could create a device with an action named Action1 and I could trigger this action with a standard software.

This way I could buy some devices and build special ones for particular problems.

So is there a standard for house automation related to a particular protocol or not, where devices can be controlled by a compliant software and where devices can communicate their capabilities ?

For those who knows what I am looking for is something like GigE-Vision but for home-automation.

[Edit] As I understand there is no high level protocol widely adopted (i.e : to switch a lightbulb). OpenHab simplifies the dilemma on what will be used (z-wave, insteon, knx, ... because it allows to mix existing "standards".

What is left for me is to decide which technology is the most convenient to use depending on multiple factors like physical chips availability, difficulty to configure them, their price, need or possibility of external microcontroller, etc

Thank you for your valuable inputs.


texts: How can I access the MCP3008 ADC chip with linux spidev?

texts:
There is quite a bit of bit-banging sources to work with this 10-bit resolution chip, but I'd like to know if this kind of chips are natively supported by Linux.

Primarily I'd like this to be in C, but I also accept answers in other language if written without some funky language-specific libraries.


texts: What is this component? It locks magnet when powered

texts:
these 2 discs are part of a vehicle gear level control. Operation is, you push button on the gear level and then you can change vehicle gear position (eg 1, 2, neutral, reverse etc)
Photo show side views of this mechanism. When button is not pushed, these 2 discs are touching each other. When button is pushed, they come apart (open position) and gear position can be changed.

Between the 2 wires, resistance is a constant 266-270 ohms. when current is flowing (there's no polarity), the 2 discs can't be pulled apart. So this forms a locking mechanism for the gear level.
Question: what is this component connected to the 2 wires???


texts:
My questions are these:

If say a 3ph motor connected to a mains supply is rated at 1400 rpm with no load at what rpm approximately does it produce its max torque?
If the same motor is run with a VFD which is set at output rpm of about 20Hz will it produce a significantly different max torque?

Thank you in advance

Haris


texts: Leakage current through push-button and switch

texts:
I am developing a battery-powered application on a custom PCB, thus power consumption is critical. I am trying to minimize current consumption with stm32L4 MCU, by turning floating pins to analog, using power-saving modes etc, so far so good (total consumption reached ~40 uA in stop2 mode).
However, after soldering a push-button (connecting ground and reset (NRST) when pressed, in parallel with 100n cap) and a simple switch (for on-off, between battery and MCU) to PCB, I noticed that consumption has risen by another ~40-50 uA (during stop2 mode). Is that normal for such parts from your experience or I am missing something else? The referred button and switch are cheap usual parts, like this and this, nothing sort of sophisticated, and also has been soldered and desoldered 2-3 times (during testing), could that be the case ?
Here is the schematic for push-button (in PCB, the button is far away from MCU and oscillator, whereas capacitor is as close as seen here. I haven't put switch button in schematic yet, it connects/disconnects the battery with VDD pins
To clarify, the whole circuit has many components that could be reason for the increased consumption. My question is if a simple push-button and/or a simple switch per se can "leak" current to ground (in terms of uA) , either because of overheating while soldering or just be being there.


texts: How do I trigger capacitive touch screen electronically (without hands)?

texts:
I would like to trigger a "touch" or "touches" to a smartphone screen electronically without actually touching the screen with my finger using a remote control somehow.

The idea would be that every time I would press the remote control, it would trigger a momentary "touch" to the screen.

Is there a way to do this? If so, can someone offer a basic schematic for how something like this would be wired along with a list of suggested components?

My question was flagged as a possible duplicate but I checked the other post and so far, a solid answer hasn’t reached quite yet.

Thanks!


texts:
I bought an Excel XL 830L multimeter with the understanding that it was a RMS voltmeter.

I also have UEI ElectroMate DM 200.

When I checked the output of my APC unit with both meters, the readings were about the same.

Is there a way to tell if a meter is an RMS type?


texts: OpAmp configuration with gain less than 1

texts:
The output voltage from AD5611 DAC is rail-to-rail, and minimum Vcc is 2.7V - therefore, the signal range is 0-2.7V. I need to attenuate this signal to let's say 0-2V range. The DAC output is very weak, so I need to use an OpAmp to buffer it. Is it a good practice to use G=<1 configuration for decreasing signal's amplitude, or is there a better way to do it?

I saw this question, but I do not think that using voltage divider would be a good idea in my case, since the DAC output is very weak, and using large resistances would introduce noise.


texts: Reduce voltage/amperage from adapter to fit another device

texts:
Complete newbie here.

So I got this old gaming console with the original adapter, which outputs 8.2V / 850mA. The cable connection with the body of the adapter is somewhat loose, though, so if you twist it in this particular way, no less, no more, and manage not to move it, the console stays powered up and it's usable.

I'd like to build my own adapter for the console using another, newer adapter which outputs 9V and 1A. The cable has two inner cables with which could (presumably?) be connected to a circuit that corrects these values so that they match the console requirements. Is this even possible? What would such a circuit look like?

I'm in Europe, in case this matters at all.


texts: the difference between K coefficient and gm in the mosfet

texts:
i know that K in mosfet is as beta in Bjt but since it represents the change in Id in relative to the change in Vgs isn't it supposed to be the transconductance gm ? but why is it different and the mosfet has K and gm so what is the difference between the two IN THE MOSFET ?
another question : does tempreture affect K as it affects beta ?


texts:
I want to drive 6 count 1.14 "IPS LED screens at the same time.
I want to show different images on all screens at the same time. Is it better to do this via SPI?
I have STM32F407 Or STM32F439 as MCU in mind.
Not: I dont want to Scrolling text.


texts:
I am having some trouble understanding the ground connected to vehicle chassis in Automotive systems.
I have read previous answers to understand why the ground is connected to vehicle chassis. I agree.

But I have some trouble in this. When the return current flows back to ground, which is the vehicle chassis in this case, does the charge gets accumulated in the vehicle chassis itself and spread along its entire bodywork? Do the charges accumulate on the chassis or where to they go? If they charges get accumulated in the chassis, wont this be a case of static electricity and one might get a shock when they touch the car chassis?

I think I have a fundamental misunderstanding of the ground concept which gave arise to this question.

Would you glad if someone could help to clear the misunderstanding this and any grounding concept.

Thanks


texts: Fast MOSFET, how to choose resistor values and how this influence speed

texts:
I've read some answers about resistors used in MOSFET and found that 1kOhm to 100kOhm is used to take MOSFET off when MCU is powering and a resistor from 10Ohm to 200-500Ohm is placed between gate and signal to keep out oscillation.

  I've a question about how much current there is on this two resistors
  and how to choose their power rate. And, resistor values can influence
  MOSFET speed?

My doubts are:
Since resistor tell how much current go through it, pulldown resistors of 10kOhm and 100kOhm should consume 0.33mA and 0.033mA respectively. And 100kOhm should be best choice for low power applications where several MOSFET are used. For gate resistor between MCU pin and MOSFET gate I'll have a 100Ohm resistor with maximum current of 33mA. But MOSFET really drain current from my signal pin? and it's correct to calculate currents in this way on resistors(since there is voltage divider, I'll have very very low current on 10-100kOhm resistor? but MOSFET influence this current?). Don't knowing how to answer about this I don't know if I should use a 1/8W resistor or 1/25W resistor.

About switching speed, this resistors influence switching on load? For example, 400-500Khz and 1Mhz are influenzed? or 10Mhz?

I'm doing this considerations on a low voltage and current MOSFETS, like 3.3v gate and 5v Source-drain, up to 1A drain. Something like this as MOSFET www.ti.com/lit/ds/symlink/csd13202q2.pdf .

My main question is quoted in the upside, additive question is to explain what I'm on doubt. I'd like a more pratical example based on values on datasheet I've liked to better reuse this on other MOSFETS.


texts: Damping factor - loudspeakers and headphones

texts:
Is there any specific reason why speaker's impedance is taken into account in the damping factor formula?

The Wikipedia article explains pretty well why low output impedance of an amplifier gives more damping, it all makes sense. But how can higher impedance speakers result in more damping? Is there more damping force? Or is it just all about determining whether output impedance is negligible with respect to loudspeaker's impedance? It's really hard to find anything on the subject except the raw definition of dampening factor.

In short: why using high impedance speakers results in more damping?


texts:
I am reading the BAV99 datasheet from ON Semiconductor.
From the table on ELECTRICAL CHARACTERISTICS (page 2)
(TA = 25°C unless otherwise noted) (Each Diode)

Forward Voltage
mVdc

IF = 1 mAdc
715mV

IF = 10 mAdc
855mV

IF = 50 mAdc
1.0V

IF = 150 mAdc
1.25V

On page 3 there is the following VI curve graph:

Clearly at 25°C - 100mA is Vf = 0.9V.
There is huge difference between the table and the IV curve.

Which source of information I should trust?
Is this (typical) and (maximum) where the table guarantees the diode won't exceed Vf 1.0v at 50mA while the graph is just typical values?


texts:
I have some doubts about the concept of power waves used in the description of the scattering matrix of an N-port component. In particular, I was wondering what is the most general and correct definition of incident and reflected power wave . In almost all the texts and sites on which I have searched,it is always taken as the impedance of normalization the same characteristic impedance of the LdT connected to the port. However from what I understand, in the more general case it is possible to assume a normalization impedance different from that characteristic of the transmission line connected to the considered port. In this case how are defined the incident and the reflected power waves?
is there any text where i can found this argument?


texts:
I ordered a SPST switch (Through hole type) from distributors and also download the cad file for PCB layout from the same website. I am now confused with the pin configuration, in the footprints it has 3 holes. Usually the SPST switch has only 2 pins right?. I have gone through the datasheet but I did not understand it completely about the pins because they have the same diagram for SPST and SPDT I suppose.
My question is, if it has 3 pins then what will be the pin connection if I want to just turn ON and OFF the circuit and If it has only 2 pins then which pin should I ignore(delete) in the footprints. I attach the footprints picture and datasheet link with this. Footprints which I downloaded are perfect with the measurements (for 3 Pins). Please let me know if u have any leads on this. Thank you
https://eu.mouser.com/datasheet/2/221/MS-100406-1174115.pdf


texts: Precision Voltage Reference 0.675V +- 0.005

texts: Is it possible and reasonable to make a voltage reference that outputs 0.675V +- 0.005 over an input of 6 to 40 volts?


texts: How is wristwatch with 10 years battery life possible?

texts:
Turns out Casio offers a handful of wristwatches with "10 year battery life". The claim is that thanks to "an advanced technology" the battery life in those watches is extended to ten years.

Now if you look at different models you see that they are rather complicated hence likely energy consuming - for example, AW-80-1AV model has both a liquid crystal display and hands and also it has LED illumination and a sound alarm.

I first thought that maybe the battery is the key. Model AW-80-1AV runs on CR2025. Energizer CR2025 datasheet specifies that this battery has nominal output voltage of 3 volts and nominal capacity of 163 mAh, so it stores 0,489 volt-ampere-hours of energy.

For comparison, typical basic model of Swatch run about three years on Renata silver oxide 390 (SR1130SW) battery that has nominal output voltage of 1,55 volts and nominal capacity of 60 mAh and so stores 0,093 volt-ampere-hours of energy.

So CR2025 stores about five times more energy, but the basic model of Swatch only has hands - no digital display, no illumination, no alarm, so it likely consumes less energy.

There clearly must be something more than a bigger battery that makes 10 years battery life possible.

How is 10 years battery life possible in a rather energy consuming wristwatch?


texts:
Information: Consider a 16-bit register of the following format is used to store a floating point number. Mantissa (M) is denoted as normalized signed magnitude fraction, Exponent (E) is expressed in excess-64 form. Base of the system is 2.

If we calculate then, we get, exponent is allotted 7 bits  and Mantissa is allotted 8 bits.

Therefore, largest number that can be represented using this information is as follows:

| 0 | 1 1 1 1 1 1 1 | 1 1 1 1 1 1 1 1 |

i.e. filling every bit with 1 and as we are looking for largest number we are having sign of the number as 0.

What is the value of the largest number that can be represented in base 10?

We will use following formula: \$(-1)^S$ * 1.M * 2^{E-B}\$ i.e. implicit normalization with biasing.

I don't understand the exponent part of the number

  How we got exponent as \$2^{127-64}\$. Why we are subtracting bias 64 from exponent 127?

Can someone explain me with proper derivation/explanation that how we arrived at \$2^{127-64}\$? Please explain it as you are explaining to naive person.

I am missing something very obvious!

Waiting for explanation!


texts: Xilinx Video Timing Controller freezes processor

texts:
I'm trying to acquire video from an image sensor using a ZedBoard with Vivado 2014.2 and I used an existing (working) video passthrough project of mine and simply added in a debayer (color filter array interpolation) IP and reconfigured some existing blocks. Here is the block diagram:

Using a very simple SDK project, the processor refuses to initialize the VTC detector config anymore. Here is the body of main.c:

init_platform();

print("Hello World\n\r");
fflush(stdout);

XVtc vtc;
XVtc_Config *VtcCfgPtr = NULL;
int Status = 0;

VtcCfgPtr = XVtc_LookupConfig( XPAR_VTC_0_DEVICE_ID );

if(VtcCfgPtr == NULL) {
return 1;
}

Status = XVtc_CfgInitialize(&vtc, VtcCfgPtr, VtcCfgPtr->BaseAddress);

if(Status != XST_SUCCESS) {
return 1;
}

printf("success\n");

return 0;

When I first power on the board, the function XVtc_CfgInitialize is called but the processor freezes internally at the XVtc_Reset function inside (xvtc.c line 232). Trying to step through this function in the debugger is also very difficult because it is somehow skipping through random lines in the function and not executing them sequentially (and the XVtc_CfgInitialize function seems to get called twice inside the debugger also?? and only freezes the second time around).


texts:
I have build a circuit with the purpose of driving a ~1000VA AC motor. The motor controller fires a triac only at zero crossings. The circuit is as follows:

simulate this circuit – Schematic created using CircuitLab

Both C2 and C1 are ceramic capacitors. R4 is a 5W resistor, the rest is regular 1/8W. The BTA208S-800E has a proper heatsink mounted directly to it.

The problem is this: after a few seconds of operation the circuit gets really hot and a little later starts to malfunction (random firing, loss of speed control).

The motor is from a old vacuum cleaner and therefore I have no datasheet for it (Google didn't yield any results either).

The circuit is one found on the internet, since I do not have the required knowlegde to calculate RC snubbers.


texts: Raspberry Pi: Voltage Converters and IO-Pins

texts:
I want to drive an LCD that needs 6V-power from a RaspberryPi. The Pi has a 3.3V logic power-pin, and a 5V power-pin that's directly connected to the MicroUSB-PowerSupply.

Am i right in the assumption that all MicroUSB-Supplies are regulated, so the PI expects / delivers regulated 5V-voltage on this pin?

What happens if connect a voltage-converter (Step-Up?) to this 5V line and connect this circuit to the GPIO-InputPins? Is that even possible? Does the circuit then have 5V or the voltage that the converters delivers?


texts: What is the inverted output for on a D flip flop?

texts:
I was asked to find the answer for this, it is a pretty vague question:

On a D Flip Flop, what is the Q' output? Look this up and write your answer in your pre-lab report.

I am trying to understand the circuit, it looks like Q' is what retains the previous value of Q when the clock is high. Can someone explain more about this to me?


texts: Switching DC/DC-converter large input and output spike

texts:
I am currently testing a DC/DC converter component that it meets datasheet specification. Link to component datasheet: http://www.tracopower.com/products/thn15wi.pdf (THN 15-2411, in: 9-36 V, out: 5 V)

This is the circuit:

simulate this circuit – Schematic created using CircuitLab

Now the problem:

The yellow line on the oscilloscope shows the output. It can be seen that at 1/400k intervals, there are voltage spikes. These are larger than the datasheet specification. They are roughly 300-500 mV. How do we remove these? Is it possible, or is our component defective?


texts:
let's consider a common wifi antenna (used in routers) like this:

I don't understand some its basic features:
1) Is it a dipole or monopole antenna? I see only one conductor, so I'd say it's a monopole. But, where is the ground plane? As far as I'm concerned, a monopole antenna needs a second metal object in order to radiate.

Picture taken from here.
The antenna may be supplied with a coaxial RPSMA cable: where does its external conductor go? It should go in the ground plane, but I don't see it.
2) I don't see even the metal conductor, but only a plastic monopole. So, I'd think that the inner part is a conductive monopole. But why is there such a plastic external shield?


texts: Controling Mosfet by 3,3V Raspberry Pi GPIO Pin

texts:
So I'm currently working on a project where I need an IR camera with two IR Leds attached to it.
The camera looks something like this:
https://rads.stackoverflow.com/amzn/click/com/B01ICLLOZ8
These LEDS are powered by the camera board an run on 3V with up to 0.3A per LED. Because these LEDS get very hot over time I only want them on power when I really need them. To do this I bought this logic level Mosfet:
https://www.arrow.com/en/products/ipb048n15n5lfatma1/infineon-technologies-ag
IPB048N15N5LFATMA1 by Infineon Technologies AG which should have a gate
threshhold voltage of 3.3V according to the datasheet.

https://www.infineon.com/dgdl/Infineon-IPB048N15N5LF-DS-v02_00-EN.pdf?fileId=5546d4625b3ca4ec015b573da84a026c

But when I connect the wires to the mosfet, the LED won't turn on. The Drain-Gate Voltage is About 2,7V, the Gate-Source Voltage at About 3,3V and the Drain-Source at 0.
The boards are wired up like this: (sorry for the bad wiring diagramm, never worked by Fritzing or something like this)

I really suck at stuff like this especially when transistors or mosfets are involved, so any help is appreciated.
Thank you!


texts: SMPS topology for combination of current controlled rail and fixed voltage rail

texts:
I'm looking at designing a LED driving power supply that can interface with a universal AC main input (~90VAC-260VAC) and produce 2 rails at the output; one a current controlled rail, and the other a fixed voltage.

In the interest of reducing cost, and since I'm looking at about a power rating of around 40W, I decided a flyback topology would be most suitable for my needs.

Is there a method for Flyback converters - or any other SMPS topologies for that matter - to provide BOTH a current controlled rail and a fixed voltage rail without significant increases in parts count or cost? As far as I can work out, the relationship between the secondary side rails prevents this.

At this point i've not found a solution and I think that i may have to implement either a second converter for the fixed voltage rail, or piggy back on the converter IC's primary side voltage source.

What options do I have for this kind of setup?

Thanks in advance.


texts: Does shutting down and repowering CPU consume more energy?

texts:
I have an internetshop that has 20 CPUs. Only 50% on average are being used throughout a regular day and almost 80-100% during saturdays. I use a Server-Client to Shutdown an unused computer but sometimes after 5-30 minute range it will be turned on again by another customer.

My questions is, will leaving an idle computer with monitor shutoff due to 5 minute idle left for 30 minutes or so be more wise than shutting a computer down and turning it on after 30 minutes.

I asked this because I though I read this before when I was a kid and I was told by mom to shutdown my Computer when we will eat for lunch or dinner and I stated that its more power consuming to shut it down and turn it on again. Atleast thats what I believed then.


texts: Problem on printing "Ethernet.localIP()" to Serial Monitor

texts:
I am using Arduino Uno and the Ethernet Shield. I have the following code:

// My custom class.
class Logger {
  public:
    // Note: The 'message' is an Arduino's String object.
    void serial(String message) {
      Serial.print(message);
    }
};

void setup() {
  Logger logger;
  EthernetClient client;

  ...

  logger.serial("Some text: " + Ethernet.localIP()); // Here I have problems (keep reading for more information)
}

When I start Arduino then the Serial Monitor displays G+dsé&¿ instead of Some text: 192.123.0.4 (note: 192.123.0.4 is the Internet IP assigned to Arduino). However, if I run Serial.print(Ethernet.localIP()); it works as expected and prints Some text: 192.123.0.4.

Why does it happen? How can I solve the problem?

Furthermore (see comments):

logger.serial("Some text: " + 'other text'); // works
logger.serial("Some text: " + "other text"); // doesn't work (error is: "invalid operands of types 'const char [11]' and const char [10] to binary 'operator+'")


texts: Why does Lidar have GPS, serial, and PPS input?

texts: Many commercial Lidar systems have GPS, PPS, and serial interfaces. What's the application and how's it being used?


texts: Pinout of / how to charge that certain battery (Lithium-ion, 3.7 V, 2 Cells, parallel, 4400 mAh)

texts:
I would like to charge the following rechargeable Lithium-ion battery outside the device where it is normally placed in (and charged):

https://buy.garmin.com/en-US/US/p/pn/010-12456-06

I don't know the pin-out and don't know much about charging Lithium-ion batteries, especially if they are put in parallel.

What I have researched so far:

The battery type is 1ICR19/65-2, meaning that the battery consists of 2 Lithium-ion cells which are put in parallel. Each cell has a nominal voltage of 3.7 V and a capacity of 2200 mAh.

From the link above, we see that the battery has four connectors. Let's denote the right connector as C1 and the left connector as C4. I have charged the battery (in the device) until the device said charging was finished, and then have measured the voltage between any pair of connectors (6 possible combinations). The results:

C1-C2: 3.7 V
C1-C3: 3.7 V
C1-C4: 4.1 V
C2-C3: 0.0 V
C2-C4: 0.0 V
C3-C4: 0.0 V

In case it matters: I have done the measurements using a reliable measurement device (Fluke).

In a discussion with some friends who are in electrically powered model aircrafts (which use cells which are put in series, not in parallel), the following assumptions were made:

C1 and C4 are the "real" power source for the device (nearly sure).
C2 and C3 might be connected to a NTC to monitor the battery's temperature for safety reasons.
C2 and C3 might be connected to some sort of "balancer" which might compensate for (slightly) different voltages of the two cells.
C2 and C3 might just be used for measuring the voltage of each cell during charging.

My specific questions now are:

Does anybody know the pin-out of that specific battery (or can anybody at least make a sound guess)?
Could anybody in short explain what might be the reason that there is 3.7 V between C1 and C2/3 and 4.1 V between C1 and C4, but there is 0 V between C2/3 and C4 (according to my understanding, there should be 0.4 V)?
Is it correct that C1 and C4 actually provide the power the device consumes?
If the answer to the previous question is yes, I believe that I can "ignore" C2 and C3 when charging that battery outside the device. I then could use one of those universal Lithium-ion chargers with moveable contacts to charge that battery. Is this correct?

EDIT 1

In the meantime, I have done a further test. I have fully charged the battery and then have let run the device until it turned off due to low battery. Then I have repeated the voltage measurements as described above. The results:

C1-C2: 2.8 V
C1-C3: 2.8 V
C1-C4: 3.2 V
C2-C3: 0.0 V
C2-C4: 0.0 V
C3-C4: 0.0 V

As we can see, the voltage from C1 to the middle connectors (C2 and C3) has dropped by the same amount as the voltage from C1 to C4. This eventually means that C2 and C3 are connected to C4 by diodes which produce a voltage drop about 0.4 V, and it eventually means that the voltage at C2 and C3 is just used for monitoring when charging. What do you think?

EDIT 2

Due to @jsotola's request, I have added an image of the label of the battery. I apologize for the bad quality. The text should be readable, though.

EDIT 3

Just in case anybody is wondering: I am asking this because the manufacturer does not offer a charger for that battery. Obviously, they expect us to always charge the battery in the device which is not acceptable to me because I need to use some more of that batteries which I'd like to charge without inserting (and removing) each battery in (from) the device just for charging.


texts: A question about using PID to improve transient response for a DC motor

texts:
I have used PID a couple of times, but there is one thing I haven't been able to understand from any literature/textbooks.

If I run a DC motor from a 12v battery for example, how can PID improve the transient response?

The Voltage (and input) is still limited to 12V, so how can the system respond any faster while still adhering to the dynamics and armature equations for a DC motor? It seems it relies on there being additional input capacity.

If it can't, why is it so common to talk about improved transient response when I read about controlling a DC motor using PID?

Thanks in advance


texts: Finding the minimum switching expression for this output

texts:
Did I do this correctly?

Step 1: [(mo' * m1' * m9' * m11') + (m9' + m11' + m13' + m15')]'
Step 2: ... apply demorgan's... resulting in....
Step 3: (mo + m1 + m9 + m11) * (m9 + m11 + m13 + m15)
Step 4: Drew K-Kaps for the 1st and second sums-of-products resulting in:
Step 5: [(W' X' Y') + (W X' Z)]*[WZ]
Step 6: Distribute WZ across the sum.... resulting in:
Step 7: WZ(W'X'Y') + WZ(W X' Z) <-- W cancels in 1st product, WZ is redundant
        in the 2nd
Step 8: Leaving me with (Z X' Y') + (Z X' W)
Step 9: can this be further simplified?


texts: Why does a larger wire cross section mean less atom-electron collisions when there must be more atoms, too?

texts:
Regarding how resistance varies with diameter I've read this simple explanation on Quora:

As electrons move across a wire, they constantly collide with atoms making up a wire. These collisions impede the flow of electrons and are what cause the wire to have resistance.Thus, if the diameter of the wire were larger, it would only make sense that the electrons don't collide as much, therefore creating less resistance due to a larger wire.

But doesn't a larger wire mean more atoms (I assume the number of atoms increases proportionally with the diameter of the wire?) meaning same amount of collisions ie. same resistance?

I don't question the fact that resistance decreases with diameter, but this explanation doesn't make sense to me.


texts: Measure current through a stepper motor coil

texts:
I have a TB6600 stepper motor driver and I wanted to measure and observe the current through a single phase (as shown on pg. 23 of the data sheet) of the connected stepper motor on an oscilloscope. The priority is to observe the waveforms shapes first and then measure the actual current flowing through each coil of the motor. I tried measuring the voltage drop across the current sense resistors Nfa and Nfb but that gave me very weird waveforms. Would measuring the waveforms directly across the coil and then dividing this voltage by the coil resistance be the right way to do this?

EDIT: Here are some waveforms captured across the sense resistor of one phase. These were taken when the stepping frequency was around 9 KHz and the stepping resolution was 1/16 micro steps. I'm not sure what to make of these.


texts: Measure 12V 35Ah battery level in arduino

texts: I am building an arduino device controlling a solar power system.  I am a beginner and would like to know what kind of part I would need to connect to the board to acheive this.


texts: Syncing Signals with Global Clocks in FPGAs/CPLDs and Edge Detection

texts:
I am a newbie in digital logic design and I'm trying to get my head around syncing external signals to the global clock in an FPGA. For example, the SCK signal/clock fed to an FPGA by the SPI Master. I understand this can be done as follows in VHDL (code taken from http://www.doulos.com/)

entity SyncClocks is
port( SCK   :   in std_logic;
        CLK :   in  std_logic;
        rise    :   out std_logic;
        fall    :   out std_logic);
end SyncClocks;

architecture RTL of SyncClocks is
begin
    sync1: process(CLK)
        variable resync : std_logic_vector(1 to 3);
            begin
                if rising_edge(CLK) then
                    rise <= resync(2) and not resync(3);
                    fall <= resync(3) and not resync(2);
                    resync := SCK & resync(1 to 2);
                end if;
            end process;
end architecture;

Simulating the above results in:

Now I know why the Rise/Fall signals are delayed by two clocks - it's because SCK goes through two flip-flops. I've also been told that it's better to act on these rise and fall signals than on the SCK signal itself. My question is doesn't this two-clock delay actually affect how the data is transferred? Let's suppose I have a microcontroller acting as SPI Master and talking to my FPGA, which is a SPI Slave. They are operating in SPI Mode 0. Furthermore, let's assume the FPGA needs to transfer some data to the microcontroller.

As soon as SS goes low the microcontroller will expect a bit to be present on the MISO line which it will sample on the rising edge of SCK. When SCK falls the FPGA has to shift out another bit onto the MISO line - but the FPGA waits two clock cycles because of our sync. and edge detection. In other words, it won't actually shift out on the falling edge of SCK it will shift out when the signal "Fall" is '1' in the above example.

Will this not cause problems on the microcontroller end? Obviously the microcontroller has no knowledge of Rise/Fall and it's clock may be running completely independently at a different frequency.

I have been trying to think this through and it seems to me that the problem will not occur if the SCK signal is slow compared to the global clock. This is because even though there is a delay it doesn't matter because the FPGA will shift out a bit 'quick enough' anyway i.e. before SCK rises. How wrong am I?


texts:
simulate this circuit – Schematic created using CircuitLab

I want to wire 6 LEDs together 2.75" apart; I'm using 2V red LEDs. I've also already calculated the resistors I need.

I'm thinking of making 2 separate circuits of 3 LEDS with each having their own 9v battery, if that makes it easier to do rather than 6 LEDS on 1 9v.

What exactly are the steps to get this done using a switch in between as well.

As of now my plan is: ( I Tried drawing a diagram here)

Wire postive end of 9v battery to a switch, then from there connect the switch to the first LED, using copper wire, i'd solder the wire to each consecutive LED, until I have all 6 connected. The from the last LED I'd connect the negative end to a resistor, and finally add a wire connecting the resistor to the negative side of the battery. Would this work?

simulate this circuit


texts: MCP3008 ADC , Reading 16 bits instead of 10 bits

texts:
I was playing around with some MCP3008 ADCs from Microchip with an Arduino.  The playground has an example for the MCP3208 (which seems to be just a 12 bit version of the MCP3008)

Well, when I tried the example, I forgot to only read 10 bits instead of the examples 12 bits.  I noticed the reading was from 0-4096

In the interest of learning, I tried doing 13 bits and could read to 8192.  With 16 bits, to 65535.

Is this dangerous to do?  As in, not accurate?  I just had a cheap trimpot and breadboard.  There was some noticeable bounce, 500 at 16 bit and about 90 at 13 bit.  The drift was around 10 at 10 bit reading.

Are all ADCs typically the same chip that is just binned based on performance?


texts: How do I calculate the wattage of a set of speakers?

texts:
I've just received a set of speakers that I want to design an amplifier for.
Two of them are 5W 4Ω and one of them is 10W 8Ω.
How do I find the total peak power output of these? I apologize for such basic questions, I am new.


texts:
About this buck LED driver...

TL/DR the questions:

1) I intend to drive the FET from a microcontroller PWM via a suitable FET driver. This open loop control scheme seems too simple. Is it a trap? I don't need accurate current control as this is for lighting my living room, 20% error on the current is okay, but I do need a wide dimming dynamic range.

2) Would a high side FET instead of low-side help with EMI by referencing the load to ground? Or will solid decoupling on VCC combined with the output cap be enough?

3) Do I need to put a filter on the output so my wires and strips won't radiate, or will it be okay with the inductor and output cap? The filter will only cost me a ferrite bead since there'll be several paralleled ceramic caps on the output, might as well split them in two groups and stick a ferrite bead in between.

Rest of relevant information:

Power Supply: 24V 10A, adjustable to 25.6V

Load: this is for a variable color temperature light which is implemented with 2700K and 5600K LED MCPCB modules. These LEDs have exceptional color rendition. In order to expand the color temperature range, I added 2200K 24V Strips and some 24V Red Strip too for extra coziness.  This is mounted on aluminium extrusion. All MCPCBs and strips are designed to be driven with 24V and include resistors.

Each LED color will get one copy of the driver above. Max currents are 5600K LEDs @ 3.6A, 2700K @ 3.6A, 2200K @ 1.5A, Red @ 1A.

LED IV characteristics, if needed:

Links to datasheets FET Inductor (10µH for high current channels, 22-33µH for the others).

Control scheme:

Frequency will be between 100 and 250k, not decided yet.

Duty cycle is constrained by minimum ON-time and minimum OFF-time, so I'd simply switch to pulse density modulation in software at very low and very high power, ie some cycles would be fully ON or fully OFF, and others would have a pulse. I'd use software dithering (aka sigma delta) to randomly distribute the pulses to make sure it doesn't flicker. This is my preferred option, also it would allow to phase shift the channels, a bit like in a multiphase buck, to reduce demands on the power supply.

When the buck works in discontinuous mode (inductor current reaches 0 and stays there during part of the cycle) each cycle results in inductor current ramping up then down which pumps a certain amount of charge into the output cap, which results in a current source controlled by frequency and ON-time. This is a nice feature. It'll be inaccurate but a 10-20% variation in output is unnoticeable anyway, and it won't flicker. Plus, at very low current, dynamic resistance of the LEDs increases which makes the output cap's RC filtering action more effective.

At high power when the inductor current is continuous, then PWM will simply control the output voltage. In this mode, the resistors on the LED modules dominate their impedance, so they can be voltage-controlled I guess. I measured the voltage on the MCPCB resistors, and it turns out that the current in each series string of LED is very well balanced. The manufacturer bins their LEDs by forward voltage, so that explains it, the LEDs are actually matched. Neat.

I know I'll have to devise a control law from desired intensity to PWM/PDM values, and that it won't be super accurate, but as long as it's monotonous and I can set the intensity and color temperature with +/- buttons on my remote control, that will do just fine.


texts: The object is to set off an alarm when the flow of water stops or drastically decreases using a Hall effect flow sensor

texts:
I have plumbed a flow sensor similar to this in the salt water line on my boat between the sea strainer and the suction pump for engine cooling over a 'salt to fresh water' heat exchanger.
When the incoming water flow stops, say, due to a blocked sea suction, or the pump impeller fails, the water flow will diminish to a large extent and the Hall effect sensor should than operate a relay which in turn sets off a high pitch 12V buzzer alarm.
While the sensor is rotating the pulses it generates are used to keep the alarm in the OFF state.
I have built a circuit from a diagram, I found online, but it keeps blowing the transistors.
Can anyone please suggest a working circuit: only on 12V DC.
The diagram should have a linear potentiometer to set a minimum flow rate.


texts: Using capacitor with lower voltage than the specified one

texts:
I'm just a hobbyist and I'm planning to build this circuit. It recommends to use a 33pF 63V capacitor. I'm in trouble to find a capacitor with this specific voltage. I only found a 33pF 50V one.

Since the power supply will be 20V, a lower voltage capacitor should not be a problem, right? What kind of problem I will have if I use a 33pF 50V instead of a 63V?

Searching the forum, I found this question, but it has two answers and each one points to one direction...


texts: What is the method to determine the XOR placing in CRC code with random generator

texts:
I'm reading a lot of different tutorials about how to implement CRC gates for different generators, But I couldn't understand the method.
For example, for the following generator, this example states that the following gate generates the valid message output

E.g what would be the circuit, if the generator was x^3+x+1 instead of x^3+x^2+1?


texts: How can I tell Microchip's XC8 compiler that I am using a custom interrupt handler? It tries to place other code at address 4!

texts:
I'm developing firmware for the Microchip PIC16F882 microcontroller using their MPLAB X IDE and the free version of their XC8 C compiler. I'm running into a small problem when trying to add a customized interrupt handler.

Because the free version of the compiler is unreasonably incompetent, I'm writing most of the interrupt handler in assembly, so that I can squeeze out the last few cycles. This works very well so far, but now I want to remove the last bit of overhead: the built-in interrupt wrapper normally placed at address 4 (this PIC has a fixed interrupt vector).

The wrapper is designed to handle generic C functions, so it spends some effort and memory on saving data and registers I do not use.

The manual is not obvious here, and I've tried two things:

Absolute Psects

  MPLAB XC8 is able to determine the address bounds of absolute psects and uses this information to ensure that the code produced from C source by the code generator does not use memory required by the assembly code. The code generator will reserve any memory used by the assembly code prior to compiling C source.

I modified their example to place my interrupt handler on address 4:

PSECT my_isr,class=CODE,delta=2,space=0,abs,ovrld
ORG 4
my_isr:
    ...

-P spec

Using a custom linker flag I can place a section where I want. Instead of messing with the ORG 4 directive I added this to the linker flags:

-Pmy_isr=4

The problem: Backup reset condition flags

Both of these correctly places the code at address 4. Problem solved!

...not so fast...

Normally, the first instruction placed at address 0 by the compiler and linker is a GOTO to the initialization routine. Then, if there's no interrupt handler, it places "random" things there, apparently it likes to continue with tables and such.

If an interrupt handler is defined in C, the first instruction is still a GOTO. Then at address 4 is the interrupt wrapper code, which eventually jumps to your interrupt handler. This is completely as expected.

The problem is with this little button called Backup reset condition flags:

  Preserve Power-down and Time-out STATUS bits at start up (PIC10/12/16 only).

When I select that, the compiler inserts code at address 0 that saves the relevant bits from the STATUS register before jumping to the initialization code:

0000 0000 NOP
0001 0183 CLRF  STATUS
0002 0803 MOVF  STATUS,w
0003 00A0 MOVWF ___resetbits
0004 2919 GOTO  __initialization

Note that the code ends at address 4, inclusive.

If I add an interrupt handler in C, the compiler knows that address 4 is forbidden, and instead replaces the above code with a NOP and a GOTO:

0000 0000 NOP
0001 2810 GOTO  0x0010
...
0010 0183 CLRF  STATUS
0011 0803 MOVF  STATUS,w
0012 00A0 MOVWF ___resetbits
0013 2919 GOTO  __initialization

But if I implement my own interrupt handler as described above, while enabling the option to save the status register, the compiler generates code at address 0 to 4, which my code then promptly overwrites, leading to a garbled mess that won't boot:

0000 0000 NOP
0001 0183 CLRF  STATUS
0002 0803 MOVF  STATUS,w
0003 00A0 MOVWF ___resetbits
0004 00F0 MOVWF 0x70         ; Oops! Should've been a GOTO!
0005 0E03 SWAPF  STATUS,w
...

I've tried using the GLOBAL directive to make sure that my handler is seen by my main.c, but that only results in an overlap warning, not an actual solution to the problem.

How do I tell the compiler that I have a custom interrupt handler?


texts:
I am studying Programmable logic array.I understood that it is a type of fixed architecture logic device with programmable and gates followed by programmable or gates.For example given logic table i find outputs(Y1,Y2) functions using K maps then i implement them. I mean something like this:

whatever i just wanted to show what i studied.
The question is

this question confused me.

I got the k map part.but how do i fill input and output tables? what are C T C?


texts:
In my schematic output of MOSFET is driving USB power, however KiCad thinks that this MOSFET pin is passive and complains that USB is not driven.
On top level schematic USB_OUT is connected to VCC, and USB_5V is connected to PWR_FLAG.

Same problem with USB shielding. All shields in my USB connectors are connected, and they are not connected to my circuit (I assume USB host will connect shield).
How I can mark such pins as "Driven"? I think PWR_FLAG does not really tell purpose (as pin is not power bus).


texts:
I am working on part (c) from the following problem:!

Vbias = 3.3V which should have been given.

Trying to solve for Vout, I first tried a voltage divider ignoring the diode.
$$3.3V * \frac{1k\Omega}{1k\Omega+2.7k\Omega} = .892V$$
which would mean that the voltage drop across the diode is .892V (?). Which would mean Vout = .892V.

This doesn't seem right to me. In the previous problem (b), I said Vout = .6V which is just Vd and it seems strange to me that adding a resistor in parellel would increase the voltage at Vout node especially if it was smaller, say 100ohm.


texts: Validation of my sinwave converter circuit

texts:
I'm pretty green and wonder if I can get my 555 oscillator, H-bridge, low pass LC filter validated. I am afraid it can be very painful making mistakes with such voltages.
I plan to use FDA59N30 MOSFETs.


texts: How to calculate temperature resistance for Ni-RTD

texts:
I would like to build a circuit to read the signal from a thermopile temperature sensor which has build-in RTD temperature sensor for cold-junction compensation. The datasheet of the sensor is here. I need to know the resistance value of the built-in Ni-RTD at some particular temperature to build the circuit. I search the web to check how can I calculate the resistance value but all I could find is the formula for a platinum RTD. Could you guide me how to calculate the resistance value for a Ni-RTD?

Thank you very much.

[UPDATE]

I have used the Temperature Coeficient Resistance (TCR) to calculate the resistance at temperature T: Rt = R0[1+(TCR)T]
However as I know the real temperature-resistance curve is not linear, is there a similar formula like the Callendar-Van Dusen equation to fix the curve?


texts: NOOB Question: Is there away to keep electrons constantly flowing?

texts: What i mean by this is we run things on lets say a battery, but eventually it runs out. Is there away we can have electrons stay trapped in a constant flow so the electrons keep getting recycled?


texts: Design a debug interface for Arduino MKR WIFI 1010

texts:
I'm a TA at university, and for the next years students in microcontroller, I will design a debug interface for the Arduino MKR WIFI 1010.

The 6 pads on the back is the debug interface as shown in the schematic

Any ideas on how to make a shield/connector? I can design/produce PCBs at the university.

Requirements:

The board should still be able to connect to the breadboard.
Interface to a 2x5 1.27mm SWD debugger
Optional: Reusability
Optional: A solution that doesn't need soldering.


texts: Pulse Down a line with Series terminations between transmission lines

texts:
I am interested in a relative edge case in transmission line of a simulation.

If send a pulse down the setup below, now obviously my rudimentary steady state electronics knows this is a basic voltage divider which will split the voltage of 3.3V between all resistors.

The setup goes from 0 to 10V from a source with a 50ohm source impedance, down a transmission line characteristic impedance of 50 ohm, series resistor of 50ohm, TL of 50ohm then a final resistor of 50ohms.

Now when the pulse goes down the line

It sees a transmission of 50 ohm and a source impedance of 50 ohms and the 10V voltage halves, so far so good.
This 5V goes down the transmission line and hits the 50ohm resistor and hits point b.
As soon as this hits point b, point b goes to 6.667V, as would be the case in steady state analysis.
the reflection of this then goes from b to a and a goes form 5V to 6.667V.

My questions

Are why does the voltage at b from a +5V pulse to 6.667V.
What is this reflection that causes point a to go from +5V to 6.667V as well.

As all connections are completely matched and there should be no reflection?

UPDATE

What I was specifically looking for was some kind of textbook or equation to explain this phenomena.

The terminology used to describe this in literature is 'discontinuity in the transmission line'

An overview of the equations governing this is shown below. This equation for the resistor specifically explains the resistor/voltages seen in my simulations.

Useful references include:

http://ntuemc.tw/upload/file/20121015094037050bc.pdf
https://ece.illinois.edu/webooks/nnrao2004/06%20Rao%20Elements%202004%20ch6.pdf (from the textbook called Elements of Engineering
Electromagnetics by Nannapaneni Narayana Rao)


texts: analogous mechanical electrical system- LTSPICE

texts:
I have created a basic series and parallel rlc circuit in LTPSICE.
According to this http://lpsa.swarthmore.edu/Analogs/ElectricalMechanicalAnalogs.html and https://www.tutorialspoint.com/control_systems/control_systems_electrical_analogies_mechanical.htm we can see that the output must be same if the values are interchanged.

In the circuit I used an inductor of 1 H, a capacitor of 5 mF and a resistor of 260.8u\$\Omega\$ for the series RLC.
For the parallel RLC we have to interchange L and C values and R=1/R as shown in the links. So, R=1/0.0002608, C=1F and L=0.005H. But I am not able to get the same output.

Can somebody help me with it?

The current in series rlc :

The voltage in parallel rlc:


texts: Wireless Sensor Node: ultra-low power energy consumption?

texts: For the link budget, I will need the power consumption of a typical wireless sensor node. Especially those of ultra-low power device, do you guys know how much power does such typical device consume?


texts: Does it matter which way you plug stuff into the wall socket

texts: I have a european socket and if you saw one you will know that you can plug stuff either way. But american sockets can only be plugged in only one way. So does it matter which way its plugged it because it works no matter what. I heard somewhere they use more power that way but i don't know if that's true