texts:
I'm trying to build a very small LED light that runs of solar power. The goal is to have it charging most of the day and maybe get about 15 minutes of "led power" per day (comparable to these solar garden lights, with the exception that they don't need to run al night). I'm looking to power a single led at preferably high brightness (say 2V, 20mA).

Since I'm looking for a small form factor I ordered these, 1v 80mA, solar cells (25mm x 30mm). Preferably I would stick to one cell to keep it small. Now I'm not really sure if, and how, I would be able to store the energy collected by the solar cell and use it to power the LED at a specific moments. Some questions I have:

Is it possible to use this a 1v solar cell to charge a battery? Maybe by boosting the voltage?
What kind of energy storage would be good: Lipo, NiMH, capacitor?
Are there circuit examples I can follow
Can these circuits build in a cheap way?

Thanks


texts:
I am designing battery charger and I want to know how to calculate max charging current for a lithium-ion battery pack. I am using Texas Instrument Chip bq24616 and their evaluation board.
Assumption:
Battery pack has-  5 in parallel and 4 in series of 18650  batteries include onboard BMS.
Base on the datasheet of the battery:
Each cell is 3.7V 2500mA
Standard Charge current 500mA
Battery pack = 14.8v 20AH
Is that mean max charging current is 5 x500mA = 2.5A


texts:
I am reading about electromechanical relays used in the first computers and I am told that the mechanical relay is closed and opened by an electromagnetic field generated by a coil on a control wire which is itself traversed by a current.
Questions:

What I don't understand is how do you control this control wire ? Don't you need a switch to also turn on and off the current in the control wire ?

Since there are also control wires in triodes and transistors too, is the answer valid for those too ?


texts: Calculating the intensity of an electromagnetic wave

texts:
I’m a bit confused when it comes to calculating intensity versus energy of a wave.

If I’m given an electronmagnetic wave with an energy of 1 eV, how do I calculate its intensity ? I know intensity is usually measured in watts/m^2.

I'm trying to understand how deep an xray can penetrate water based off its intensity, but I only know its energy/wavelength.

Thanks!


texts: Internet access to LoPy (ESP32) using its GPIO pins

texts:
LoPy is a LoRa module which uses ESP32 chipset. It has WiFi and Bluetooth connectivity for Internet.

In my setup, I have certain interference issues, so I can't use WiFi nor Bluetooth to connect my LoPy to the internet.

Is their some way I can provide Internet to the module using GPIO pins? I am thinking of this setup:

I will have a Raspberry Pi, which will be connected to the Internet either using USB tethering or LAN cable. This RPi will provide Internet to LoPy using serial communication through its GPIO pins.

However, I am not sure how I will achieve "providing internet access through serial port". How can this be done?


texts: Is there a downside to using multiple relays simultaneously to increase relay capacity

texts:
I want to install a relay to my fusebox which is controlling whole basement with machinery.

Relays that I have have got 2A limit each, and I have 32 relays. Can I just use all of them for the same line and assume the relay's limit is 64A ?

Is there any risk of doing this?


texts:
I've got a successful buck converter design using an LM3485. It's got a MOSFET gate driver output pin that swings between Vin and Vin-5V - perfect. My MOSFET is a SQ1431EH-T1-GE3. It has a maximum Vgs of 20 volts and Vds of 30 volts. The input voltage is spec'd to range from 17-24 VDC. The output is 15 VDC @ 2A (max).

I'd like to try replacing the LM3485 with an MC34063 configured for an external MOSFET. I'm not enamored of the hysteretic 3485 because as the input voltage increases so does the switching frequency, which leads to increased dissipation in the MOSFET if it can't keep up.

Here's my naive design attempt:

Note that since I drew that schematic, I've changed the MOSFET to a SQ1431EH-T1-GE3, as the SI3443 part doesn't have sufficient Vds.

With two 100Ω resistors, the amount of power going through the resistors is too high, but with higher values, the switching slows down. At the moment, I'm set to use 1KΩ from gate to SWC and 560Ω from gate to source. In simulation, that makes the gate waveform kind of a mess, but the switching still seems to happen pretty darned fast (judging by the simulated drain voltage plot). Currently I'm simulating the design, as I've not gotten boards yet.

But the big question is that when I google for MC34063 and external switching, what I typically see is that DVR is connected not to the MOSFET source, but rather to SWC to configure the internal switch into a Darlington configuration. My design instead simply sets up the inner transistor to switch on the outer one, which in turn will pull down on the external MOSFET gate. Seems like it's poe-tay-toe/poe-tah-toe to me, but is there something I'm not understanding properly about the Darlington configuration?


texts:
Considering that USB C can output up to 20 volts and 5 amps, what would be required to wire up a 12 volt battery to a usb type c female port?

I want to charge my phone using my motorcycle's 12 volt battery at full potential of usb c.

Assuming I purchase a simple IC for managing and negotiating the power delivery over usb c such as this: https://www.rohm.com/products/interface/usb-type-c-power-delivery/controller/bm92a50mwv-product

What would be my next step?


texts: PLL design VCO and RC filter connection in real sense and not in block diagram level

texts:
The above give basic block diagram of PLL, but according to my understanding after the output of Charge pump with loop filter , VC ie the control source for the VCO is connected to which part of the circuit design of the basic VCO (based on cross coupled pair -negative resistance). The image for VCO is given in below. Does the control source for VCO connected to the current source at bottom in real life?

Ps: I have added one more updated varac design. Is it like that


texts:
After some research, I think I have quite a problem on my hands.
I have a project on an FPGA where I store a 32 bit binary value in a 32 bit memory register. The stored value ranges from 0 to 4000 in decimal.
I would like to display this decimal number from 0 to 4000 on a 4 digit 7 segment display. I know it would be significantly easier to display the number in hex format but I would like it in decimal.
Only way I can think of is a huge look up table but this is really tedious, or changing my system to calculate values in BCD instead of binary.
edit
Or a binary to bcd converter but again would be slow
edit
My architecture is 32 bit so I am just storing this value in a 32 bit register.
What are ways to solve this problem? I am not sure how to go about solving this problem and would just like to be pointed in the right direction if anyone knows how to do this


texts: I want to remove 3 LED's from a small circuit board. Need a bit of help

texts:
I have a 4 port USB hub with 3 INCREDIBLY BRIGHT led lights on the circuit board I would prefer removed.

I've googled a bit and found a user of this site actually describe the process very well.. Here

My knowledge of working with this stuff is next to none, and I do not have a soldering iron.

But, this user suggests soldering off or 'cut off with a knife', a TINY resistor next to each LED. I've poked at it a bit and it doesn't seem to want to budge. I'm worried I will break something or scratch it if I try much harder..

So my main question is, I believe I could much easier pull the led's off with pliers. Would this work as well? Is this dangerous? Or any tips on getting the resistors off without a soldering iron?

Here is a photo of the top with the resistors in question. Click for a high-res version.

And here is a photo of the bottom with the LED's I'd like to yank out.

All help is appreciated. Thank you.


texts:
So I am working with this DAC and I am trying to attach reference voltages and outputs, but I am confused.

Looking at this image of the board, what is the connection to VOUT ? How do I connect to those 5 gold circles? I think only the center is live. Should I also connect +/- 10 volts to VREFP and VREFN?  The data sheet seems to be ambiguous about if I should do that, or if I can attach to +5V to VREF and that will work as well? I also do not know what that port/connector is?


texts: STMicroelectronics Evaluation Board - What is a "Standard APG connector 4x36"?

texts:
I am interested in using the STMicroelectronics SPC56M-DISP eval board but have been unable to locate a connector for the interface. I want to connect it to an EVAL-L9788.

The ST documentation for these evaluation boards says they have a "Standard APG connector 4x36". What connector brand and part number is a "Standard APG connector 4x36"? I searched but could not find any mention of it outside of ST documentation.


texts: What is the reason of that 1 kilo ohm connected to the microphone? Why always too high resistors are used? I couldn't find any explanation. How do we calculate these values?


texts:
There is a new electronics waterproofing material / technique branded as Liquipel. Not much info is available, but supposedly it is a hydrophobic compound that is applied to the target electronic device by using vapor deposition in a vacuum while ionizing the target device so that the Liquipel particles are attracted to coat every nook and cranny of the device on the microscale.

Unfortunately, no one has chemically tried to identify the composition of Liquipel yet -- for all I know, it could be the same as Rain-X or something equally cheap. And it is not possible to buy Liquipel canisters; the company only applies this coating as a service.

Given that electrostatically-targeted, vapor-deposited, microscale hydrophobic coating seems to be the best way to waterproof arbitrary electronic devices, what is the state of the art in non-proprietary versions of this technique or a similar technique? Does anyone know a chemical that would work in this way? Any instructions for DIY vapor deposition? Or is there any simpler approach, like dipping the whole circuit board in some hydrophobic yet sticky liquid?


texts: Matching an amplifier to speakers and subwoofer

texts:
I've got a couple of old Bose speakers and bass and I'm looking to wire them with an amplifier so I can use them with a computers sound card.
The speakers' manual can be found here.

For the speakers:
they are rated 4-8 ohms and 10-200 watts per channel. I was wondering if either of the following amplifiers would be good enough to drive the speakers at decent volume with decent sound quality:
amplifier 1 or amplifier 2.

For the bass:
the bass has the same rating as the speakers, but the bass was connected in-between the amplifier and the speakers. It contains two subwoofers. I'm thinking I could rewire the two subwoofers in parallel and then use one of the previous amplifier boards. Would this work and would the amplifier board be strong enough to power the bass?

Also, correct me if I'm wrong, but I could connect a potentiometer in between the audio source and the amplifier input to act as a volume switch.

Thanks for the help.


texts: How to remove spikes from switching transistor?

texts:
I am building a steady current source which delivers steady current (0-20mA) to an LED. The brightness of the LED (current) is controlled through a potentiometer's voltage and a voltage follower as shown in the picture below. Further, I want to blink (modulate) this LED with a square pulse frequency of 2kHz using a switch between the transistor gate and the voltage follower output.

The problem is that every time the switch closes, spikes are produced at the base and as a result at the source. Even when I reduce the current of the LED to 1mA (example picture 2), the spikes don't go away. Only when I set the current of LED to 0 do the spikes dissapear.

So the question is how can I remove/reduce these spikes? Is there some way?

[


texts: Overcurrent Protection Relay, How do I simulate it with Raspberry Pi?

texts:
I'm using RPi and MCP3208 to simulate an overcurrent relay. I managed to level shift the AC signal and now I get the voltage reading at 0-3.3V.

As this is an overCURRENT relay, I was stuck for a month reading books and online resources. All of them keep talking about pickup current and delay time which relates to when the relay will break the circuit. I understand some parts but not others.

My understanding:
If the pickup current is higher than the acceptable current rating, it should break the circuit.

My question:
Now what? How do I get the values needed from the table below (specifically TMS)? Do I need current sensor for this?

p/s: If my question is too much, is there any easy explanation or can anyone link me to any easy books/websites for this?

My current data:


texts: How to produce sawtooth waveform from square waveform?

texts:
I have a question pertaining the changing of square waveform to sawtooth waveform using OpAmp.

Following the picture below, I have to create a sawtooth waveform from a square waveform.

It seems that I need to make the square waveform into the positive side of the sawtooth waveform. Then, use the same square waveform, give it a 180° phase shift and make it into another positive sawtooth waveform (180° from the first positive sawtooth waveform). Finally, use summing amplifier to combine them into a full positive sawtooth waveform.

Am I correct? If so, which opamp circuits (integrators, etc) should I use to make the square waveform to be the positive side of the sawtooth waveform?

Thank you for your time.


texts: Where does current go after flowing to earth?

texts:
I know similar question have been asked several times, but I didn't get exactly the answer I was looking for.

I actually want to ask something that perhaps can worded as a practical question, but I think it would not clearly represent the thing I wanted to ask, so I'm framing this as a hypothetical question.

Assume earth has been cut into two pieces somehow (and for some reason, gravitational force is on vacation so 2 parts are hanging around as shown and are not moving), the one half has 3 phase generator with neutral earthed and it's one line and neutral are supplying a single phase load provided with adequate earth fault protection on other side.

Now suppose, I've connected an ammeter between 'earth' in two halves, and earth fault takes place on load causing current to flow to the earth, will my ammeter show some reading (to an astronaut I've recruited)?


texts: simple question regarding frequency modulation (FM)

texts:
I have a question on frequency modulation. For example, the following signal is frequency modulated:

y(n)=sin(2*pi*(400+cos(2*pi*4*t))*t).

Since the maximum of cos function is from -1 to 1, so I should expect to see that, y(n) has frequency components between 399 to 401. However, if I take the fft, the result is not so. Can some one please explain why?


texts: Calculating the input current drawn by a MOSFET driver

texts:
I am using a PIC32MZ's OC pins (PWM mode, fault disabled) as input to a dual MOSFET driver (ISL89163 A). I need one OC pin to drive 3  drivers i.e 6 inputs each. The pulse width would be around 100~150ns with a repetition frequency around 50~100Hz. The PIC's datasheet ( http://ww1.microchip.com/downloads/en/DeviceDoc/60001191E.pdf page 565) says each I/O pin should be able to source/sink 25mA. I found quiescent current graphs on the driver's datasheet but I am not sure how much its input pins would need. How do I calculate the input current needed by the driver and make sure the PIC pins would be able to source it? Using separate OC pins for each driver is not an option since I am doing something similar on the remaining OC pins too. Also, it's a requirement that each of the 6 inputs shown below are roughly the same, so I do not want to go into synchronizing the OC outputs if I use separate OC pins. I am using FDD8447L for the MOSFET. Here's what my circuit roughly looks like now:

EDIT:
Should have noticed the 10uA input bias current specified on the ISL89163 datasheet earlier, dunno how I missed it. Anyway, does that mean the PIC OC pin needs to be able to source/sink only 60uA (10uA x6) of current. How do my input 100ohm resistors affect this?

simulate this circuit – Schematic created using CircuitLab


texts: Can radar/lidar sensors for self-driving cars be designed to ignore deliberate interference?

texts:
A previous question asked about how to avoid interference between sensors on different self driving cars.  The answer was that systems could be designed to avoid interference, with correct signal coding, time sharing, etc.

A separate question that arises is what happens when a bad actor deliberately attempts to jam the sensors?  Can deliberate interference with the radar/lidar be avoided, or does the driving software just have to include a fail safe mode (e.g. pull over until the interference is gone) to handle it?

Going further, would it be possible to assure that the sensors were not receiving deliberately false but apparently valid data that could cause the vehicle to crash?


texts: Remove power line hum and noise from DC source

texts:
We are testing our device in a local RF compliance center next week.

I spoke with them on the phone and they suggested using a car battery instead of an AC powered DC supply.  The reason they gave was that their DC source is noisy.

TI don't want to introduce stray noise and causing our product to fail. I want to clean the DC signal, getting rid of both power line hum and any high frequency EMI.

I was looking at EMI feed-through filters and external chokes but couldn't find anything less than about 10kHz, any recommendations?

How can I remove power line hum on a DC signal?


texts: How does stereo audio signal works with shared ground (e.g. headphone cables)

texts:
I have a rather simple question about my fundamental lack of knowledge how is stereo signal transferred along 3 wire cable (L,R channels and ground)?

The problem with me understanding it is because as I understand the signal is AC voltage for both channels, right, but how are they then sharing the same ground? Wouldn't that produce crosstalk for L and R channels because they both use ground to carry the negative part of their AC signal?

What am I fundamentally misunderstanding?


texts: Can i use 47uf instead of 10uf in LM317 Adjustable voltage regulated circuit?

texts: Please refer the images above for the circuit, my question is can i use 2x47uf cap instead of 2x10uf cap in the circuit, since i dont have any 10uf cap in my hand, Thanks.


texts:
A 1MW power plant producing power constantly for 24 hours will produce 24 MWh a day. Is that right?

If it is, I don't understand when it says, in http://www.beaconpower.com/files/Flywheel_FR-Fact-Sheet.pdf, that the 20MW energy storage plant can release 25kWh at 100kW for 5 minutes.

What does that mean? I don't get why they refer the plant as having 20MW, when all it can do is release 25kWh at 100kW for 5 minutes. Also isn't 25kWh over 5 minutes at a rate of 300kW?


texts: Why does adding a capacitor increase voltage gain?

texts:
I'm trying to get a bit of intuition when dealing with transistor amplifiers. I recently watched  this tutorial, and wanted a bit more elaborate explanation about why adding the cap circled in blue greatly increases gain.

I am aware that caps block dc signal, so adding the cap shorts the ac signal to ground, but why does that drastically increase the gain?


texts:
I am supposed to provide in my circuit, multiple analogue inputs (max 5V) to (multiple) amplifiers and I am planning to do it using micro-controller and external DACs. When I researched a little I came to find out that there are two ways of doing that (when using external DAC ICs interfaced with the micro-controller). One way is to use a single DAC IC with multi-channel outputs, and the other is to use multiple DAC ICs (one for each analogue signal required).

I have previously worked with ADCs, and never with DACs. I used two ADS8319 and interfaced them with my micro-controller using SPI-interface and 4-Wire CS Mode Without Busy Indicator (data sheet page number 22).

Now my question here is that if I want to use multiple (six to be exact) DACs for e.g this one DAC8560, am I capable of doing it using this DAC8560 ? The reason for asking this question is that in the DACs data sheet I cannot find any exemplary diagram which shows the usage of multiple DAC over SPI interface, neither its mentioned somewhere the usage of DAC8560 in multiple configuration (like it was mentioned in ADS8319's datasheet (page 22) ). One more question regarding this is that in ADS8319's data sheet its clearly shown the usage of 4-wire interface while using the SPI (as what I know about SPI is that it is 4 wire interface according to the WIKI as well), however in DACs datasheet, the IC clearly has 3 pins for the serial peripheral communication, which is confusing for me (whether it would support the usage of multiple ICs or not) as this 3 wire for SPI is new for me.

P.S I know using a single DAC with multiple channel outputs for e.g this one could be an easier solution to it, but I am not sure if doing that requires high programming skills (since I think I would be supposed to control DAC outputs on a single IC so I think that would require some kind of programming complexity and I am not sure if I am capable of doing that since I am not a good programmer). So can you please comment on that as well, whether using a multi-channeled output DAC requires some complex programming on the part of micro-controller (i would be using Arduino UNO) or not ?

Your kind replies and suggestions would be highly appreciated. Thankyou!


texts:
I am looking to power up my Teensy LC and my RGB strip from the same power supply, which is a 3.7V Li-Ion battery 3000mAh. The teensy can work perfectly fine with 3.7V.

The problem is when it comes to the RGB strip. Since I have about 40 LEDs, and it says that every LED takes 0.2W at 12V, I guess I will have around 0.7A current draw.

I looked up the internet for DC/DC converters, but they all have low output current. I need at least 0.7A and max 1A. Do you think I will have to boost to 3.7 to 5V and then 5V to 12 V ? Or is there another way ?

Thank you


texts: Wiring an SSR rasberry pi with an SSR-10DA

texts:
I have an SSR (pictured) that I intend to wire up to a European 220v appliance (in Norway) and a Rasberry Pi. It appears from this post that no diode is necessary (with an optional 1k resistor).

So then I would just take the 3.3v power, via a 1k resistor, to the GPIO pin to the SSR, then a ground back to the RPi?

SSR in question:

Update:

After wiring things up, it appears the SSR has power regardless of whether there is a voltage over the control side (see pic). Any suggestions?


texts: Should I remove the termination resistor from the CAN Bus transceiver module?

texts:
I develop a CAN-BUS receiver (logger) with an ESP32 and CAN-BUS transceiver.

The CAN-BUS transceiver modules which I found and bought have both 120 Ohm termination resistors. But the CAN-BUS to which I want to connect this (in a modern motorcycle) is already terminated on both ends. I want to connect my device to the CAN-BUS service connector (like an OBD2 ELM327 adapter).

Do I have to remove the resistors from these modules to make sure the bus is only terminated on both ends?

Or do I have to keep these resistors to make sure the transceiver modules work correctly?

Is it possible that the CAN-BUS or any device on the bus will be damaged if I don't remove the resistor because the load is too high?

I bought several of those modules and I can do "try and error" if necessary.

Here are two pictures of those modules:


texts:
I have a board on which core for VME64 bus is implemented and it communicates with other boards on VME64 bus using only 1 connector (P1, 5 rows, 32 pins on each row, total 160 pins) instead of 2 connectors (P1 and P2). I am trying to understand its working in both Bus controller and Remote terminal modes.

I have to modify the connector pinouts to make room for free pins on the P1, 160-pins connector. There is lot of info available about the bus but what I could not find out is the minimum pins required to use VME64 bus?

I can live with only 24-address lines on the bus. But I don't know which other lines I can compromise on to make room for free pins on the P1 connector?


texts:
I was recently building a larger slayer exciter. I've been trying out different coil ratios, coil materials, different transistors and many circuit variation, most of them just excited a fluoroscent bulb, just at different a brightness. But the last one gave me small arcs.

The most recent one I made had about 850 turns in the secondary to 4 turns in the primary. I ran it at 40V with an old power adapter[I made that by soldering two 20V DC power bricks in series](I don't own/can't afford a Lab Bench power supply).

I was using a TIP41C, and burnt 1 out, because careless me left it powered on for a long time without a heat sink. This one gave me half cm arcs when I leave the free end of the coil in air.

Then I switched to a MJE3055T. It worked pretty well, and added 2mm to my 5mm arc, but Looking at all those pictures of 2 inch arcs on youtube, I was not that happy with mine. I recently bought 1500 meters of 37AWG magnet wire(for about 9$) and I really need some advice from experts/professionals/engineers, to build another one, which can give me large arcs with my 40V supply, a 40KV ceramic capacitor, 18AWG primary coil and a TO-220 type transistor I guess(TIP41C, MJE3055T, and I've got a few other high voltage transistors that I salvaged).

Thanks a lot for any help guys! Would really appreciate some advice!


texts:
I'm studying this RF Power Amplifier and I'm curious about the drain-gate feedback shown as R3 and C6:

What is the purpose of the R-C feedback?
What is this mechanism known as?


texts:
I need some help designing a circuit for a timelapse slider. Please bear in mind i am a beginner with electronics, so have mercy!

The motor will be pulling a trolley (very slowly) along a set of rails while a camera on the trolley takes pictures at certain intervals. The effect is used so that in the footage the camera will move slowly while time is moving very quickly (bad explanation). Some examples of this can be seen in this video - https://www.youtube.com/watch?v=ZwzY1o_hB5Y

The DC motor i have is rated at 12V 0.06A 4RPM. Its a high torque geared motor.

Currently i use the motor with a AA (1.5V) battery which moves the trolley 0.5 metres every hour. The trolley is attached to the motor by a timing belt and pulleys (which can be seen in the image below). This is ok but i want the option to increase the speed as well as other features.

Features Wanted

-ON/OFF switch
-option to vary speed (potentiometer?)
-direction switch
-removable battery - 9V preferred
-proximity switches - one on each side of the slider to stop the trolley from being pulled too far
-Ideally i would like the components to fit onto a space the size of the black piece of wood shown in the last photo here.(roughly 170x90mm)
-possibly a battery life display (that could be turned off to conserve battery)

Some Key questions

Is it possible to build my own circuit for under £15 ?
How long would a 9V battery (Duracell) last in this setup?
Will powering the motor with a lower voltage than its rated for break the motor?

Any answers (or questions) are welcome. Thank you for reading all the way down here!

Below are some pictures of my current setup


texts: Troubleshooting small home made electromagnet

texts:
I used bolt cutters to cut a piece from one of those wire campaign poster sign legs, took that piece and wrapped it (all in the same direction) with wire that was unwrapped from a small fan motor, then hooked it up to a 9 volt battery. I chose that as the iron core because I read that bolts are hardened iron and aren't as good as "soft iron". I verified that magnets stick to it. The result is nothing, not even the slightest capability to move a paperclip (that does stick to magnets). Lick test tells me the battery is live. I'm sure the wire is coated because it was visible when I was burning the coating off the loose ends (and because of where I got it.) I know the circuit is complete because hooking a little bulb with it in series makes it light up.

My suspicions:

1) The iron wire core I chose isn't suitable despite sticking to magnets readily.

2) The iron is too big/small to be affected by the too big/small copper wire wrapped too few times with a too weak power source. (But it should show at least a little magnetism, right?)

3) The wire shorts in such a way that it bypasses the part where it makes an electromagnet.

4) I've forgotten some fundamental detail about how this works.

Pictures below. How can I determine what went wrong and/or how can I make sure it works on my next attempt?

Left to right: Where I got the wire,  the electromagnet I tried to make, another segment of wire, and the Lego brick its intended to fit in

A close up. The plastic pieces on the ends are just to hold it inside the brick. Its put together with super glue.


texts:
I have some technical drawings and I am looking for the name of a pair of components (or maybe two disctinct components) whose symbols I cannot identify. I understand one is a type of switch controlled by the other component which is connected to a NI-6008 USB card. The two are drawn separately but I do not know if they are linked in reality, simply avoiding additional wires on the schematic.
What are the following symbols?


texts: accuracy of magnetic field sensors in electrical vehicles

texts:
For coordinate system alignment purposes, as demonstrated in the figure, I want to use the smartphone's virtual orientation sensor. However, the virtual sensor is using a combination of acceleration, gyroscope and magnetic field sensors in order to calculate this orientation. Since I want to use an electric vehicle, I think that the accuracy of the magnetic field sensor part could suffer due to the high electrical powers within the vehicle.

Does have anybody experienced accuracy problems with those kind of sensors and electric vehicles?

What could be an alternative approach to align the reference systems?


texts: esp-12 power supply + backup by 4F capacitor 5.5v + ME2149, is it working?

texts:
I made my own energy meter using esp-12, I need to save data to esp spiffs when loss grid power, In this case, I do not need wifi than esp turn to modem-sleep mode, so working current is about 20 - 25mA and I think 5 seconds is enough to save data. After searching quite a lot I choose using a super capacitor to backup power, it is 4F 5.5V. Here the diagram, is this diagram working?

Here datasheet of ME2149 ME2149 Datasheet PDF

Module ME2149 here Aliexpress ME2149 Module

Super Capacitor here Aliexpress Super capacitor

My question is this diagram is working?

Thanks

Edit: the capacitor wiring is reversed, my mistake when edit image, pls pass it


texts: Operational amplifier output voltage calculation

texts:
This problem asks for \$ v_O \$ in terms of circuit problems.
I solved the problem. But my solution has
\$ \large v_O = -R_4 (I_1 + \frac {V_1}{R_2} + \frac {V_2}{R_3}) \$
\$ I_1 \$ term as you'd see.
But according to solution manual it is like that.

I wonder whether my solution is correct.


texts: Power consumed by light bulbs in series, parallel?

texts:
simulate this circuit – Schematic created using CircuitLab

So the problem I've been given is to determine whether the power consumed by a string of lights increases or decreases as more lights are added in parallel (and a similar problem concerning increasing number of bulbs in series). The problem states that the source is a standard wall electrical outlet (I'll assume it's like the ones in the US since that's where I'm at).

Now, I don't know a whole lot about electrical standards anywhere in the world, so I'm not sure what exactly comes out of a wall, in terms of electricity and current. My understanding is that the current alternates (which doesn't really make sense to me because my light bulbs aren't flickering on and off like a sine wave). If resistance remains constant, that means the voltage is alternating too, since \$V = I \times R\$, so the value of \$V\$ is fluctuating proportionally with \$I\$

I was under the impression that, at least in the US, wall outlets had something like 120V and the current actually drawn is variable depending on your load. I thought that since the current is alternating, then as discussed above, the voltage must be alternating too, and maybe the 120V refers to the amplitude of the alternating voltage. Please correct me if I'm wrong, as it seems crucial to understanding the problem.

So if you add light bulbs (resistance) in parallel, the overall resistance of the load decreases. If your max voltage remains constant, then more current would be drawn, no? Similarly for bulbs in series, the total resistance increases as bulbs are added, so the drawn current would be reduced. So for parallel bulbs, your power would increases, since \$P = I^2 \times R \$ and the \$I\$ term is increasing faster than the \$R\$ term is decreasing. Likewise for series, the power seems like it would decreases, since the \$I\$ term decreases faster than the \$R\$ is increasing.

How far off am I?


texts: Identifying a LC oscillator circuit and solving resonance frequency

texts: Could someone please identify what type of oscillator this is in the first stage. I'm not quite sure if it is a Colpitts or not and also could someone specify the resonance frequency calculation if it is possible?


texts:
First, I'm a new bee to electronics.

With the above circuit, why the output is 0.6V instead of 0V?

I wanna achieve input HIGH at base and output HIGH, input LOW with output LOW. but the LOW voltage is not 0V.

Where is the problem and how I edit it?


texts: Is there a way to measure current and fault current better than the ACS716KLATR-6BB-T

texts:
I need to measure 2.5A (ac) and detect fault current. Currently I am using a Isolated Current Sensor with Overcurrent Detection ACS716KLATR-6BB-T Datasheet

I am using this part because space is the most important restraint, and of course next is cost. I need 3KV isolation as well.

My question is is there a smaller way to measure current and faults on the high side? Is there a smaller way to do this?

Working voltage is 100 - 277V (ac)


texts: Data rate for 1080p@30fps Video in BT.656 8~10 bit format?

texts: What is the data rate for 1080p@30fps video in BT.656 8~10 bit format? Does the MAX9271 serailizer support FHD@30 in BT.656 format? According to the datasheet the serial data rate is 1.5Gbps.


texts: Condenser Mic Noise Problem on SoundCard

texts:
I am very new in Electronics.
I have Condenser mic with this following Spec in Short:
model HT-D38 (brand HTDZ)
Power Supply: Phantom Power 48V/DC3V

It is working on Mixer by 48v Phantom Power very well.
but When I am connecting it to Sound card which produces 24V phantom Power it is coming electrical background noise.

I understand it is blame of  unsufficient Power supply, I have tried to add several kind of  Resistors on out from Mic and Capacitors but anyway the the noise is coming anyway.

Please if somebody can suggest how I can resolve this problem, it is not problem adding something in Circuit it is acceptable for me.
Thank you very much in advance for support.


texts:
I am trying to make a simple MACC to work, but it does unexpected things.
The multiplication is not working. 00001 * 00001 outputs 00000

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity macc is
    Port ( clk : in  STD_LOGIC;
           rst : in  STD_LOGIC;
           en : in  STD_LOGIC;
           A : in  STD_LOGIC_VECTOR (4 downto 0);
           B : in  STD_LOGIC_VECTOR (4 downto 0);
           P : out  STD_LOGIC_VECTOR (8 downto 0));
end macc;

architecture Behavioral of macc is
    signal product : STD_LOGIC_VECTOR (8 downto 0);
    signal acc_in : STD_LOGIC_VECTOR (8 downto 0);
    signal acc_out : STD_LOGIC_VECTOR (8 downto 0);
begin

    product <= A*B;
    acc_in <= acc_out + product;

        acc: process is
        begin
        wait until rising_edge(clk);
            if (rst = '1') then
                    acc_out <= (others => '0');
            elsif (en = '1') then
                    acc_out <=  acc_in;
            end if;
        end process acc;

    P <= acc_out;

end Behavioral;


texts:
I am doing the tracks for a PCB design. In the lab earlier when I put a ground zone over the board all of the connections that had to go to ground disappeared, as expected... it made me happy.

Now I get home and try to do the same because for reason it disappeared and it does nothing to any of the ground connections. I was just wondering if I have missed some step.

At the moment I press "zone mode" and default is selected in the traces list. I then draw it over my PCB design. Under the settings I select bottom copper and ground then press ok. Is this right?


texts:
Assume I have a capacitor with capacity \$C\$ and is charged to a voltage level \$V_a\$ and then discharged.

1) During discharge it dissipates \$E\$ joules of energy. What is the equation to find the final voltage \$V_b\$ of the capacitor after \$E\$ joules have been discharged ?

2) After the same capacitor discharges and reaches \$V_b\$, we re-charge it up to \$V_a\$ again. Assume the charging current is (\$I\$) (Amps). What is the equation to find how much time (\$t\$) it take for the capacitor to charge from \$V_b\$ to \$V_a\$ ?

I am looking for equations without resistance (\$R\$) involved, as I do not know the resistance of the circuit (MCU based), but only the energy consumption of the load.

I googled for these equations, but could not come up with a specific answer. I have learnt these equations in school/university, but have forgotten now.

thank you


texts: How to measure mA level DC current at double MCU VCC

texts: I want to measure a small 1-20mA current with my MCU. It has a transimpedance amplifier I thought would be useful for the task. I'd like to to just measure the voltage difference across a resistor. The only problem is the voltage for the current is around 6V and the MCU VCC is 3V. How can I safely measure the current here without blowing up my MCU. If I can I'd like to do it cheaply and as small as possible. One last thing if it makes a difference, the current can be changed but once it's set it'll be pretty steady state. So I don't need to measure a waveform or anything, I just want to take a sample or two.


texts: How to model an equivalent resistor V/I in LTSpice

texts:
Consider the output of an optocoupler in series with a 27k resistor connected to a fixed voltage of 66V.

In LTSpice I am able to plot the current in this circuit as a function of the input signal. However I need the equivalent resistance value. In other words 66V divided by the current found. I can not find the way to do that in LTSpice.

I am able to transfer the plot data to Excell and handle it over there but it would be nice to solve the situation in LTSpice.

In short:
Is there a way to modify the plot Y axis from current to resistance?


texts: Modelsim simulation doesn't work Pleas help

texts:
I can't for the life of me figure out why I don't get an output from this testbench and entity that i've created.  I've tried it several different ways with the OUTPUT y never making it out.  I know this is a noob question, but I am a noob so that's ok.

HERE is my entity:

Library IEEE;
use ieee.std_logic_1164.all;
-----------------------------------------
PACKAGE my_vector IS
    TYPE vector_array IS ARRAY (Natural RANGE <>) OF STD_LOGIC_VECTOR(8-1 downto 0);--(Natural RANGE <>,Natural RANGE <>) OF STD_LOGIC;
END my_vector;
-----------------------------------------
Library IEEE;
USE work.my_vector.all;  --using my package
USE IEEE.STD_LOGIC_1164.all;
USE IEEE.STD_LOGIC_ARITH.all;
USE IEEE.NUMERIC_STD.all;
USE IEEE.STD_LOGIC_ARITH.UNSIGNED;
use ieee.NUMERIC_STD.UNSIGNED;
-----------------------------------------
Entity mux IS
   GENERIC ( M : INTEGER := 8;
             N : INTEGER := 3 );
    PORT (  a   : IN vector_array ((2**N)-1 downto 0); -- ,M-1 downto 0);
            sel : IN INTEGER;                          --STD_LOGIC_VECTOR(N-1 downto 0);
            y   : OUT STD_LOGIC_VECTOR(M-1 downto 0));
END mux;
-----------------------------------------
ARCHITECTURE logic of mux is

signal test : STD_LOGIC_VECTOR(8-1 downto 0);
    BEGIN
    y  <= a(sel);
END logic;

HERE is the TESTBENCH:

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
-----------------------------------------
PACKAGE my_vector IS
    TYPE vector_array IS ARRAY (Natural RANGE <>) OF STD_LOGIC_VECTOR(8-1 downto 0);--(Natural RANGE <>,Natural RANGE <>) OF STD_LOGIC;
END my_vector;
-----------------------------------------
Library IEEE;
USE work.my_vector.all;  --using my package
USE IEEE.STD_LOGIC_1164.all;
USE IEEE.STD_LOGIC_ARITH.all;
USE IEEE.NUMERIC_STD.all;
use ieee.std_logic_arith.UNSIGNED;
-----------------------------------------
entity tb_GenericMux is
--  Port ( );
end tb_GenericMux;

----------------------------------------------------------------
architecture Behavioral of tb_GenericMux is
constant TIME_DELTA : time := 10 ns;
--DUT-----
COMPONENT Mwidth_by_Ninputs_MUX IS

   GENERIC ( M : INTEGER := 8;
             N : INTEGER := 3 );
    PORT (  a   : IN vector_array ((2**N)-1 downto 0); --,M-1 downto 0);
            sel : IN INTEGER;--STD_LOGIC_VECTOR(N-1 downto 0);
            y   : OUT STD_LOGIC_VECTOR(M-1 downto 0));
END COMPONENT;
------------
use work.my_vector.all;

signal input :  vector_array((2**3)-1 downto 0);--,8-1 downto 0);
signal slt   :  INTEGER;--STD_LOGIC_VECTOR(3-1 downto 0);
signal outp  :  STD_LOGIC_VECTOR(8-1 downto 0);

begin
--connect DUT
DUT: Mwidth_by_Ninputs_MUX port map(a   => input,
                                    sel => slt,
                                    y => outp);

PROCESS
BEGIN
input(0) <= "00000001";
input(1) <= "00000010";
input(2) <= "00000100";
input(3) <= "00001000";
input(4) <= "00010000";
input(5) <= "00100000";
input(6) <= "01000000";
input(7) <= "10000000";

slt <= 1;
wait for TIME_DELTA;
slt <= 2;
wait for TIME_DELTA;
slt <= 3;
wait for TIME_DELTA;
slt <= 4;
wait for TIME_DELTA;

END PROCESS;

end ARCHITECTURE Behavioral;


texts: LEDs in parallel - How does this circuit behave?

texts:
I am given the following circuit for a project (The real one has 120 LEDs) and I am requested to program the Arduino such that if one of the LEDs is to fail, system will detect the failure and light another set of 120 LEDs.

Each LED has a forward drop of 1.9 Volts in this case.

simulate this circuit – Schematic created using CircuitLab

I tried disabling one of the series connected LEDs, however I couldn't read a notable difference in the analog input. My theory is that when one line of LEDs are disabled, this decreases the voltage on R5 momentarily, so other lines simply draw higher current to stabilize the circuit again. However I am not an analog guy, so that may be incorrect.

My questions are:

Is my theory correct on this behaviour?
What is the good way to detect the failure in this case? Can it be done somehow utilizing this circuit, or is a complete redesign necessary?
What would be the method/approach if I were to hand calculate the voltage values? I tried to use the datasheet of ULN2003A to find Vce to start, however I couldn't make use of any values, because there wasn't any values for 5V input. How do professional designers use these values?


texts: Connecting batteries in parallel doesn't produce greater amperage

texts:
Having two 3.7V "3000mAh" Rechargeable Li-ion batteries, I tested connecting them in series and parallel.
Using a multimeter, I measured the amperage of single batteries and it's about 6A. When connecting them in series, the voltage is doubled (it becomes 7.4V).
When connecting them in parallel, I expected that the amperage will be doubled, but it's not. It remains 6A.
Why does this happen? How can I increase the amperage using more batteries?
From what I know, when connecting batteries in series makes the voltage to be increased and when they are connected in parallel, the amperage is increased–but in my tests this last expectation didn't happen. Why?
This is how my circuit looks like:

My two batteries, in parallel, connected to ampermeter.


texts:
I want to improve my project to be more robust, because it needs to be available 24 hours a day. Initially, my design had one microcontroller and a USB (FT232R) interface. The FT232 is 5V powered and my microcontroller is 3.3V. I was using an external regulator to supply power to the microcontroller, but, to minimize possible issues that the approach of using two voltage sources can bring, I thought to use a bus powered solution.

I read on FT232's datasheet that the basic rules for USB bus powered devices are as follows:

On plug-in to USB, the device should draw no more current than 100mA.
In USB Suspend mode, the device should draw no more than 2.5mA.
A bus powered high power USB device (one that draws more than 100mA) should use one of the CBUS pins configured as PWREN# and use it to keep the current below 100mA on plug-in and 2.5mA on USB suspend.
A device that consumes more than 100mA cannot be plugged into a USB bus powered hub.
No device can draw more than 500mA from the USB bus.

My concerns:

Trying to satisfy this rule, I analyzed the current consumption of the microcontroller:
The microcontroller is a dsPIC33EP64MC202, and it has the following current's consumption according to its datasheet:

DC Characteristics: Operating Current(IDD) at +85°C 3.3V 70 MIPS:
 Typical ........................................... 41 mA
 Maximum ........................................... 60 mA

Absolute Maximum Ratings:
 Maximum current into VDD pin ...................... 300 mA

Considering the operating conditions, it seems to be ok to use a bus powered approach, but, I'm afraid of the absolute maximum current that it can draw and what could happens if it draws this amount of current. So, my doubt here is, should I consider a high power USB device or not? Would be safe to consider a non-high power USB device?
I read what "Suspend mode" is, I understood that the host (the computer in this case) will decrease current when there is no activity on the bus for a time greater than a few milliseconds and, afterwards, it will decrease the current until shutdown the device.
Well, if this is right, I have a problem here, my device will receive a requisition via USB and, after a time, a few milliseconds, it will answer the requisition. How can I handle with this? The device can not be shut down so early in the middle of an operation
I did not understand this rule. If my device is a high power USB device, I should use one of the CBUS pins configured as PWREN# and use it to keep the current below 100mA on plug-in and 2.5mA on USB suspend. But how I will do this if my microcontroller is BUS powered? I need to configure the FT232 before mounting it on the PCB?

(4 & 5). The rule (4) is sufficient to rule (5), so, why specification on rule (5) was necessary?


texts: Moving AI IP into new FPGA. Is the trigger for reading ROM an address change?

texts:
I'm confused about the trigger for reading ROM.
I want to read one of 4 k bytes but it appears the clock is free running and may be continuing to read the same address while I'm processing the byte I read.
I can't use a wait value, since every byte has a different processing time. Sorry for this simple question that is not answered in any of a 100 tutorial files.


texts: Calculating maximum power dissipation based on contact area between two metal conductors

texts:
I am trying to figure out how to properly calculate the minimum contact surface area based on the maximum required power dissipation. Let me explain..

I am creating a custom semi-circular metal tab that makes an electrical connection to a metal strip. The metal tab will be connected to a system that dissipates 7 watts. Assuming that I know that I need to support a maximum power current draw of ~.55A @ 12 V (this is where the ~7W power dissipation comes from), how can I best calculate the size of the contact surface area that the two metal contacts need to share in order to support the specified current dissipation. Please see the very crude drawing below. I am trying to determine the contact surface area highlighted in the blue circle.

Here are the givens...

I have control over the choice of metal for both the contact and strip
I can decide the thickness and size of both contacts.
A voltage drop of no more than .5 Volts may be tolerated
A temperature rise of no more than 10 C may be tolerated
The load has a current draw of ~.55 A @ 12 V (i.e. ~7W)

I am not looking for anyone to do the work for me, I am just looking for some help with the proper equations to use. Thanks.


texts: How would a ring oscillator with even number of inverters behave?

texts:
Intuitively, I understand that with an even number of stages, the output of the last would be the same logic level as the input of the first, so that the output eventually latches to a certain logic level. Whereas, with odd number of inverters, the outputs switch and the resulting frequency is determined by the gate delay.

However I also read that Barkhaussen's criterion does not apply to non-linear circuits, and cannot be used to evaluate the behaviour of a ring oscillator. If that is the case, how do you explain the sustenance of oscillations in the oscillator? More precisely, what would the transient behaviour be like, that leads to oscillations?

Also, is there a necessary DC operating point that either oscillator converges to in the steady state? Is the operating point "stable" in the case of even and "unstable" in the case of odd stages?


texts: Induced voltages and flux within a transformer and their polarities

texts:
This is a multifaceted question, and is more to see if I understand what happens inside a transformer. I understand the general idea behind transformers: Alternating voltage that is applied to the primary is "mirrored" at the secondary and its size is dependent on the ratio of turns. However, the polarities of the induced voltages and "cancelation" of flux within the core is a little confusing to me. So let's start at the beginning:

Applying a sinusoidal voltage, \$V_{AC} = V\sin(\omega t)\$, to the primary causes current \$i_p\$ to flow through it. We can see that \$i_p\$ is proportional to \$-\cos(\omega t)\$, and so is the flux \$\phi_1(t)\$. Since the flux intercepts the primary coil, it induces a voltage in the primary, and according to Lenz's law, that voltage will point in the direction that opposes the change that caused it. In other words, if we denote this new voltage by \$V_p\$, then

$$V_p = -n_p\frac{d\phi_1}{dt},$$

where \$n_p\$ is the number of turns in the primary. We see that \$V_p \sim -\sin(\omega t)\$, so \$V_p\$ points in the opposite direction to \$V_s\$. The two opposing voltages are why \$i_p\$ is very low when the transformer isn't loaded. Also, if they had canceled each other completely we'd have no current and therefore no flux. Is all of this correct so far?

Now we attach a load to the secondary, and the same flux, \$\phi_1\$, induces a voltage in the secondary, and it is
$$V_s = -n_s \frac{d\phi_1}{dt},$$
where \$n_s\$ is the number of turns in the secondary.

Like, \$V_p\$, \$V_s \sim -\sin(\omega t)\$, and this is where it gets tricky for me. The voltage that comes out of the secondary should have the same phase and polarity as the voltage that is fed into the primary. What I get here is that they have opposite polarities! Additionally, it is not clear to me how we physically decide on the polarity of the secondary's leads, what's \$+\$ and what's \$-\$? Then there's also the way the two coils are wound which also affects the polarity.

One way for me to settle this is to think of Lenz's law again. If we denote the current induced in the secondary as \$i_s\$, then Lenz says that \$i_s\$, being induced by \$\phi_1\$, will flow to oppose the change that induced it. I take this to mean that \$i_2\$ will flow in such a way that the flux it generates, \$\phi_2(t)\$, will oppose \$\phi_1\$. So no matter how the secondary coil is wound (CW or CCW), the induced current, \$i_2\$, will "arrange" itself so that \$\phi_2\$ will oppose \$\phi_1\$. Depending on what the secondary is wound, the polarity of this signal will change, as this diagram shows.

Am I correct so far? If yes, then why do we choose the "top" lead to have the positive polarity? And how do we square the whole business with the induced voltage, \$V_s\$ having the reverse polarity to the source voltage that feeds the transformer?

Now comes another part I'm not sure about. \$\phi_2\$ acts against \$\phi_1\$, therefore reducing it and reducing \$V_p\$, so the primary draws more current from the source. Therefore \$\phi_1\$ gets big again, and I assume it more or less cancels the reverse flux \$\phi_2\$, so really \$V_p\$ doesn't exist across the primary. I've seen several places say that the transformer wants to maintain the high flux in the core. Is this why?

Lastly, is it just me or Faraday and Lenz's laws are really just for illustration purposes? I don't think that what happens inside the transformer is reactionary like that where one current flows and then another reacts to it. For instance, we don't see a reverse flux, but breaking it down this way helps us understand why the end result is the way it is.


texts: Is this a ac three phase motor with a dynamic braking control?

texts:
I am an electrical apprentice and this question popped up on my exam, and then again on an exam  under a different topic, and I have to review it.

What type of motor control is this?

note: I received enough answers to the question above. Thank you.

My other question is with regard to the role of the varistor.

Is it to vary the stopping time? If someone would please guide me in the right path, I would be most obliged.


texts:
I found a this DIP socket that has "press-fit" pins. What are these actually used for? Are they literally used as a replacement for soldering? If so, why would anyone do this since that would seem to decrease permanence and increase cost?

https://www.mill-max.com/catalog/download/2017-11:096M.pdf


texts: Side-channel leakage and instruction types on microcontrollers

texts:
Since the end of 90s, it is known that side-channels (e.g. execution time, power consumption, electromagnetic emanations) of computation platforms can be analysed to recover information on data being manipulated (e.g. keys in cryptographic calculations).

On load/store architectures, it seems that the amount of leakage depends on the type of instruction. For instance, some papers report successful results when exploiting leakages related to intermediate values manipulated by memory instructions (e.g. load/store instructions) while ALU operations do not seem to produce any exploitable leakage. See for instance this paper for experimentations on ATmega2561 processor (using power consumption as side-channel) and this paper for experimentations on ARM-Cortex M3 processor (using electromagnetic emanations as side-channel).

How could we explain, from an architectural point of view, that ALU instructions might be less prone to information leakage than memory instructions?


texts: Why Positive-going clock transitions used in certain ICs

texts: Why do certain ICs like 74ALS174 use an inverter so as to make a Positive-going clock transitions occur instead of Negative-going ? Why can't we just save expense of an inverter by removing it and allowing the more natural Negative-going clock transitions? (CP in image)


texts:
I have a 1-wire network using cat5 cable.  There is a bus running along the roofspace of the building and the sensors are on stubs off this bus.  The bus along the roofspace is about 25 metres long and the stubs are between 1 and 5 metres long.

I understand that a linear bus is better than one having stubs or a star configuration.  It occurs to me that without having to replace any cabling I could rewire each sensor to be directly on the bus. By using one of the twisted pairs in the Cat5 cable to run the DQ and Vdd down to the sensor and then use another pair (in the same cable) to run the DQ and Vdd back up again the bus could continue without having made a spur.

Would running the out and back wires inside the same sheath be OK? Would it improve the network or would it cause interference, make the total cable length even longer and be worse than just having spurs on the bus?

UPDATE:

The bus is driven using a Maxim DS2482 at standard 1-wire speed.  The devices are not using parasitic power.

I am about to add some more sensors onto the bus.  I am wondering if there would be any benefit in changing the way it is wired since I will soon have an opportunity to do so.

I would not be able to replace the existing cables, hence the idea of running two legs of the bus inside the same physical sheath to create a linear bus.  Does this sound like a good idea worth pursuing further or is it pointless?


texts: Should a VFD be turned off when not in use, as much as possible, or should it be left turned on all the time?

texts:
I have bought a Noritake itron vacuum fluorescent display, to use in an Arduino project. A menu with settings will be shown on the display, and the user can interact with it by using some buttons.
My question is:
When the user does not use the VFD display to change settings and such, should I program the Arduino to turn off the filaments inside the display? Should I leave the display on all the time?
I'm thinking that if I leave the filaments turned on all the time, with the individual segments not lit, I will get sputtering, and that's undesirable. Also, if I leave the display fully on (both filaments and individual segments) then in time, I will get either burn-in or fading of the phosphorus on the individual segments. I have it currently set that if the user doesn't interact with it for 10 seconds, then the whole display shuts off, including filaments, but I'm thinking the constant power cycling in the filaments will thermally stress them, leading to premature failure. How would be best to leave a VFD when not using it? What sort of idle time should I set, if 10 seconds is too short? An hour would work?


texts:
I am exploring the mainboard of an Epson 3010 projector. This particular projector has internal speakers but does not have an audio out and - as I have built my own external audio amplifier - I wanted to modify it and extract audio from the projector.

At this moment, I am NOT considering an HDMI audio splitter. I am aware of that solution but I do not wish to go that way.

I opened up the projector and backtracked the integrated speakers wires to a chip that is a MAX9736A, a class D audio amplifier, conveniently located on top of the mainboard. Note: I wasn't able to find a schematic of this board, so I have to try to guess how it works.

https://datasheets.maximintegrated.com/en/ds/MAX9736-MAX9736B.pdf

From the datasheet it looks like this chip takes a line level input and outputs an amplified audio signal. I connected my oscilloscope (ground to chassis) and (for example) I can see the "PWM" speaker output. With the probe on pins 23..26 I see this wave that changes according to the input, and I can hear it while being played.

In the following image, my setup, with the area where the chip lives highlighted in a circle.

However, I expected to see a signal when putting the scope probe on pin 18 - instead I get a (noisy?) fixed 2VDC. Kind of surprisingly, I get some sort of noisy waveform that matches the input on pin 19, that is the feedback channel, connected to the input through at least a resistor and a capacitor (in the picture, see pins 5 and 6 for the left channel). Note I did not use the analog ground (pins 13,14), as my scope is not floating and I want to exercise caution. Now, this is just an audio signal, I'd expect levels and bandwidth to be fairly simple to see on a scope, I'm not exactly debugging DDR memory chips. I even tried to mess with AC coupling and bandwidth limiter, I gave a 440Hz audio input to the projector - I can hear it well in output - but I cannot detect it on pin 18.

My questions are:

Why cannot I "see" a good audio wave input on the oscilloscope? I suspect I'm missing something obvious here
If I manage to solder a line audio cable to pins 6 and 18 and ground to 13,14, what trouble can I expect? Please note I have an OK lab equipment with stereo microscope and I'd be technically able to perform the rework, in fact this chip is not even that small. But I typically work mostly on fully digital boards and this audio stuff escapes me.

EDIT:
I have soldered an audio cable to the entry point of the input network of the left channel of the MAX9736A. I cannot hear anything on that input, not even a faint signal. Difficult to make a good picture, but I soldered it with the aid of a stereo microscope and I have made sure they are good. I checked with a DMM that all grounds, AGND, PGND, main ground plane are all shorted with the chassis and the ground prong in the AC connector. (and yes, I even floated my fully-plastic cased oscilloscope to see if it made a difference)

Note: before and after this modification, the projector's integrated audio works perfectly with no issues.

EDIT2:

I have probed the circuit again with the oscilloscope; the probe point is the entry point of the input network as explained by the answer below:

The result is this, an extremely noisy waveform that in fact, might be a 440Hz audio input:

EDIT3:

The extremely noisy signal persists even if I solder a short lead to the AGND of the chip, I float the scope (yes, I know bad practice) and ground my probe there:


texts: Failed to get Device ID - PICkit 3 & PIC16F684-ICD & AC16205

texts:
Like it is already mentioned in the title I have question regarding this dev stack:

MPLAB X IDE v1.80
PICkit 3
PIC16F684-ICD (datasheet)
AC16205

There is image of how things are connected (I don't think there is a problem):

Powering settings:

There is simple program I am using for testing:

/*
 * File:   main.c
 * Author: Primoz
 *
 * PIC16F684
 *
 * Simple test program.
 */

#include <xc.h>

// CONFIG
#pragma config MCLRE = OFF      // MCLR Pin Function Select bit (MCLR pin function is digital input, MCLR internally tied to V
#pragma config FOSC = INTOSCIO  // Oscillator Selection bits (INTOSCIO oscillator: I/O function on RA4/OSC2/CLKOUT pin, I/O function on RA5/OSC1/CLKIN)
#pragma config WDTE = OFF       // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = OFF      // Power-up Timer Enable bit (PWRT disabled)
#pragma config CP = OFF         // Code Protection bit (Program memory code protection is disabled)
#pragma config CPD = OFF        // Data Code Protection bit (Data memory code protection is disabled)
#pragma config BOREN = OFF      // Brown Out Detect (BOR disabled)
#pragma config IESO = OFF       // Internal External Switchover bit (Internal External Switchover mode is disabled)
#pragma config FCMEN = OFF      // Fail-Safe Clock Monitor Enabled bit (Fail-Safe Clock Monitor is disabled)

void main()
{
    TRISA = 0b111101;

    PORTA = 0b000010;

    for (;;)
    {
        ;
    }
}

I successfully programmed the device only few times. Most of the time I get this output:

Connecting to MPLAB PICkit 3...
Firmware Suite Version.....01.28.72
Firmware type..............Midrange

Target detected
Failed to get Device ID

So my question is what could be a reason for such an odd behaviour? How can I make it work?

If you need any additional information, please let me know...


texts: Debugging long 1-wire line with Raspberry PI

texts:
I'm trying to setup a network of temperature sensors for my house connected to a Raspberry PI. I'm using Cat6 unshielded cable (data + ground running on one pair, 5v/ground running on another). To test. the lines (5v, GPIO4, Ground) from the RPI are connected to a breadboard, which has a pair of punchdown blocks pushed into it;  ~60m of unshielded CAT6 UTP is run between the two blocks. If I connect my DS18B20 direct to the RPI without the CAT6, it works fine - the RPI detects it and it shows up under "/sys/bus/w1/devices"; if I connect it to the punchdown block at the far end of the CAT6, I either get nothing at all, or an unstable collection of "ghost" devices with incorrect IDs under there. Interestingly, if I connect the sensor direct to the RPI, but also connect the CAT6 after it (with nothing on the end), it doesn't work any more.
Things I've tried:

Using RPI internal pull-up on 1-wire bus, or using external 4.7k resistor between the RPI 5v line and the data line
Putting a schottky diode between the ground and the signal line next to the sensor (Using a Vishay 1N5817 - should I be using a different diode?)
Powering the sensor with a 5v line from the RPI GPIO, or letting it use parasite power from the data line
Putting a 100 ohm resistor in series with the data pin of the sensor (this shouldn't really be necessary with only one sensor - it seems mainly relevant for reducing signal reflections in networks with longer stubs - but I tried it anyway)

I've also measured the resistance and capacitance of the cable, which come to about 6ohms each way for resistance, and 2.8nF of capacitance between the data line and ground. AFAICT the resistance should be fine (these devices draw very little power). I'm not sure if the capacitance is an issue but I would assume not since this is pretty much bang on for CAT6 cable (14pF/foot) and a 60m run is well within what should be possible for a 1 wire bus over CAT6 from everything I've read.
What else can I try? Ideally things that don't require an oscilloscope since I I don't currently have one...


texts: Is this passive headphone mixer design safe?

texts:
I am looking for a cheap solution to allow me to connect a single set of headphones to two computers I am using. I don't need volume mixing or selection, I just want to merge the two signals.

I found this instructable, that has a very simple design. He essentially connects five jacks ground pins together, and then joins the left and right channels of each input jack to the corresponding pin on the output jack via a 1k resistor.

It almost seems to simple to me. I do not want to blow up the output jacks of my computers by applying an odd signal to them. Is this design safe to use? Can anybody explain what the purpose of the resistors is, and why it works or won't work?


texts:
I'm thinking of creating a project with a RPI3 and LED strip for home automation. And I want it to keep it as «clean» as possible, less cable mess is better. The RGB LED strip is working at 12VDC, and the RPI3 works at 5VDC.

So I was thinking of soldering a PCB that fits on top of the RPI3 GPIO pins, the PCB should contain 230VAC to 12/5VDC PSU and RGB LED driver (3 MOSFET's).

The question is about the PSU, is it a good idea to mount a switched 230VAC PSU ontop og the RPI3? Or can it be dangerous?


texts:
I am new to this site. I am now working on microcontrollers. I successfully burnt hex file to 89S52 using arduino as a programmer. But I want to program 89C52 as this is the cheapest atmel microcontroller in my area. There are programmers available online that costs nearly 14.5 US dollar. But I want any cheap way as I am a student and cannot afford that much. Is there any way to do that? Or can I use arduino rx and tx pins to program 89C52?

Thanks in advance


texts: Do vibration motors vibrate in both directions at equal magnitude?

texts:
I'm using two vibration motors for my robot and to have it move forward, I have to solder the leads of the motor in the way shown in the picture. Previously when I soldered the leads of both motors the same way, the robot kept turning round and round. Switching the leads of a motor helped solved that, but not completely.

I've noticed that the robot while moving straighter, tends to turn in favor of one direction over the other. This issue is even more apparent when the robot is supposed to turn in a direction responding to a light stimulus. I've noticed that the robot turns much quicker in one direction than the other.

I don't think it's an isolated case, I've assembled a few copies of the robots and all of them exhibit the same bias in turning toward a particular direction over the other. And the that bias is also in the same direction.

So I'm wondering for a vibration motor, do they vibrate the same if a voltage is applied to the leads and then that voltage polarity is reversed?

EDIT: Link to datasheet added


texts: When bit-banging I2C using 2 PIO lines do these lines still need to be pulled high? Obviously using a dedicated I2C bus the lines must be pulled high as the pins are open-drain outputs but PIO pins aren't open-drain.


texts: Measuring the L/R ratio of an LR circuit

texts:
I have the circuit below (fig.1) that I found in a board of an old machine.
The input signal is a square wave with 10 Hz frequency and 10 V amplitude.

I measured the waveform on the primary side of the transformer with an oscilloscope (fig.2) and found that the time 5*L/R is equal to 7.8 ms.

I calculated this time value by measuring the inductance: it was 1.6 H with an internal resistance of 330 Ω.

With these measured values I found that the time is equal to L/(R1+r) = 1.6/(5600+330) = 1.3 ms, where L is the inductance of the primary, R1 is the series resistor in the circuit and r is the internal resistance of the coil.

And to be sure that my LCR meter is good and there's no problem, I put a coil instead of a transformer and I found that the answers are very close.

Then I thought: can we consider the transformer and coil with the same logic or should we consider the transformer differently?


texts: Weird problem with ADXL345, Buzzer and Arduino

texts:
I've set up a Serial port via a Bluetooth module (HC05). I'm using a JavaFX app that I wrote to read the serial port, plot the acceleration values (via ADXL345) and write back to the serial port an alarm bit (1 for ON and 0 for OFF) whenever a certain function of accelX reaches over a value.

The weird part is, whenever Arduino detects ON bit and turns on the buzzer, my acceleration values become quite noisy! I've checked my codes both in Arduino side and Java side and couldn't find a problem.

Then I put a LED instead of buzzer and to my surprise it turned on without interfering with accel. readings !!

I really don't know what is the problem with buzzer. Can anyone help?

Here is my suspicion:
I'm using a break out board for ADXL345. I'm not sure whether it can tolerate 5 volts. I connected Uno's 3.3 volt to it's Vcc and I'm using I2C for communications. (with two 4.7k pull-up resistors connected between it's SDA and SCL pins and Uno's 3.3v).
Could it be that the buzzer when turned on somehow draws so much current that interferes with those pull up resistors?

Here is the photo of my setup (the lower red line is 3.3v and upper red line is 5 vols both coming from Uno. All grounds are connected together):

And here is the readings of accels. in IDLE:

And I get these reading out of Serial Port:

But whenever I tilt the breadboard (limit for alert is 20 degrees), it correctly beeps, but due to noisy accelerations, buzzer starts, stops, starts in a random pattern:


texts: Contact sparking even with flyback diode

texts:
I'm building a circuit to measure both voltage and current given to a solenoid valve 24V DC 15W. In parallel to the valve is a voltage divider with 470k + 100k Ohm resistors. In series with the valve is a 1 Ohm 4W resistor. In parallel with both valve and 1 Ohm resistor is a 1n4007 Diode correctly positioned in order to actuate as a Flyback Diode. But yet, whenever i remove the +24V contact of the valve, simulating a opening of a Relay, I still see some sparks flying around. They are easily noticeable. I've measured the peak voltage and indeed it has lowered: from -10V (minimum readable value) to -250mV. But there are still sparks! Is it ok or will it damage a operating relay?

simulate this circuit – Schematic created using CircuitLab

thanks!


texts: When did they start making SMD2835 and others

texts:
i'm trying to build the chart of LED efficacy and power change over the past couple of years.

does anybody know when did they start making 2835, 3528, 3014, 5630? google gives me 2015ish for 2835, but I do remember using them way before 2015.


texts:
I try to calculate the Q value of APD photodetector with these parameters:

$$R \hspace{0.1in} (response) = 1$$
$$M \hspace{0.1in} (magnification) = 10$$
$$k \hspace{0.1in} (ionization \hspace{0.1in} constant) = 0.1$$
$$N_{th} \hspace{0.1in} (noise \hspace{0.1in} density \hspace{0.1in} of \hspace{0.1in} thermic \hspace{0.1in} current) = 12 \hspace{0.1in} pA/\sqrt{Hz}$$
$$P_1 \hspace{0.1in} (optical \hspace{0.1in} power \hspace{0.1in} of \hspace{0.1in} '1' \hspace{0.1in} bit) = 0.5 \hspace{0.1in} \mu W$$
$$f \hspace{0.1in} (frequency)= 193.1 \hspace{0.1in} THz$$
$$r_e \hspace{0.1in} (extintion \hspace{0.1in} ratio) = 0.05 \xrightarrow \quad r_e = P_0/P_1$$
$$B_R \hspace{0.1in} (bitrate) = 10 \hspace{0.1in} Gbits/s$$
$$B_e \hspace{0.1in} (electrical \hspace{0.1in} bandwidth) = B_R$$

I use as reference the explanation of "Principles of Optical Communications" of José Capmany and it applying the following equation for Q value:

The possible values of Q are:

77.499
2.9592
0.019739
0.3947

I search more information about how I can calculate the Q value  in APD photodetectors. However, I haven't found any way to get one of the above results. Somebody could help me?

Thanks!


texts: How does this current source circuit work?

texts:
I am using an  LTC3623 5A buck regulator as a programmable current source. In the application notes there is this circuit:

I'm trying to understand how Iout can be 0A with this setup. According to the graph it is when Vshunt is 0.5V.

So there would be 0.5V across the 10k to ground, therefore the fet is turned hard on trying to get all of the 50uA. But if Iout is connected to a 10 ohm load to ground, it would effectively make the two 10k resistors connected in parallel between Iset and ground, or a single 5k resistor to ground. Which would set Iset to 0.25V and therefore the output would be non-zero.

Would it work if the bottom 10k was removed and the non-inverting input of the op-amp was connected to the top of the fet instead of the bottom? That way when Vshunt is 0.5V it would short to ground and set Iset to 0V.

Edit: Meant inverting.


texts: Smoothing cap vs filter for full wave bridge rectifier circuit

texts:
I am designing a circuit which requires high-voltage DC. My plan is to step-up my mains (120VAC) with a transformer and then pass that through a FWB. After the FWB, I want to smooth the signal into a nice DC. I am aware that this is often done using a smoothing capacitor.

I'm modeling my circuit after the schematic below:

But the circuit in that drawing has an inductor in the filter circuit, near the place where I just expected to see a smoothing cap.

What's that inductor there for?
What is the name for this kind of filter? (if not just "LC filter")
Why would I do this instead of just have a smoothing capacitor?


texts:
Is there any way to monitor what is being sent to the WT-11 module via UART?

I'm trying to implement deep sleep on the WT-11 and can run the iWRAP "TEST DEEPSLEEP" command successfully but the deep sleep lasts for less than a minute.  The iWRAP datasheet says that this command "Puts the module into deep-sleep after a delay of half a second until woken by a reset or activity on UART."

I don't think I'm doing anything that should end deep sleep.  Is there something lower level on the ArduinoBT that may be interferring?

I also can't get the "SLEEP" command to work, this may be related.

(The code I'm running is here)


texts: Decoupling capacitors: what size and how many?

texts: Lots of chips nowadays require smoothing capacitors between VCC and GND for proper function. Given that my projects run at all sorts of different voltage and current levels, I was wondering if anyone had any rules of thumb for a) how many and b) what size capacitors should be used to ensure that power supply ripple doesn't affect my circuits?


texts:
This is the circuit I made - designed it, calculated it, built it:

simulate this circuit – Schematic created using CircuitLab
Q1's and Q2's collector current was 5mA, while Q3's was 1mA. Sine wave at the input had 1Vpp at 1kHz. Negative feedback should work since there is a 360 degree shift between input at base of Q1 and base of Q2. Rf2 was firstly decided to be 10k, then it was replaced by potentiometer.
This circuit didn't work as I expected. I expected that if some distortion would occur inside sine wave then it would be corrected by negative feedback or/and differential transistor pair, and the amount distortion being corrected would be controlled with Rf2 (less gain - less distortion).
I made the distortion by adding another sine wave (1Vpp, 3kHz) to the base of Q3. The actual results couldn't be compared to the desired ones as they weren't even close to the desired ones.
As the result, the output at collector of Q3 was distorted in the same way as the signal at the base of Q3 - should there be pure sine at collector of Q3?
But then I scoped the signal at the collector of Q2 and only there was the sine wave I expected to be at the output of amplifier (under the condition, that base of Q2 was shorted to C1, otherwise with rotating the potentiometer Rf2, the signal would rapidly approach the distorted one).
Sine wave at the collector of Q2 versus distorted signal at the base of Q3 (not on the same voltage scale).

I think that there is still a little gap in my understanding of differential amplifier because I am struggling with this for a while and I haven't made one useful circuit including diff. amp.


texts: How do multiple users connected to a wireless router receive their signals?

texts: In other words how does a wireless router with multiple users work? I know that routers use electromagnetic waves radio waves, but how does information get sent to the user it is intended to? and if the router emits all signals in a particular frequency(at least that is how I think it works) does this in theory mean that information can be captured by one user that the information was not intended for just by being in the proximity of the network?


texts:
I'm busy designed a PCB that will use a Raspberry Pi's GPIOs to to drive several optoisolators. Additionally I'm also interfacing with an IO module that works with HIGH > 1V.

Because of the number of optoisolators I'm using I don't want to overload the Pi's GPIO's and planned on using a ULN2003 to do the heavy lifting and drive the opto's.
Additionally, I would like to use the inverted output of the ULN2003 to drive the aforementioned IO module. My knowledge is mostly in digital systems, so the only place I have used the ULN2003 before was to drive some LEDs from GPIOs.

[Keep in mind, my knowledge is mostly digital systems, and the occasional n-channel mosfet, which in my mind is also "digital". I have virtually zero knowledge of transistors.]

Now I'm struggling to understand the 1.0V approximate "collector-emiter saturation voltage". I thought that there would be a close-to-zero ohm resistance between the OUT pin and GND of the ULN when the IN pin is high. But now I read on a guide:

  Keep in mind that you will have a voltage drop of about 0.9v-1.0v over
  the UL2003 when in circuit.

I'm a little bit lost here. I've drawn up a schematic to help. All GND's are common.

Does this saturation voltage mean that XMM1 will measure about 1V when the input is high? Multisim doesn't want to simulate the ULN.
I found a Toshiba component that looks identical to the ULN2003 but uses DMOS (I assume this is closer to N-channel mosfets, which I'm more familiar with). The Toshiba TBD62003 (datasheet) which is also slightly cheaper than the ULN2003.

Can anyone tell me if it can be used as a drop in replacement for
    the ULN2003 in the schematic above. (Just hook up the GND pin,
    load's negative side connected to OUT1 and GPIO drives IN1)? By the
    looks "equivalent circuit" it uses a n-type mosfet?

EDIT: I found a very useful application note by Toshiba which shows that is pretty much a drop-in replacement.


texts:
I have written a short program to measure the room temperature using a temp sensor, LM335. The power supply is fixed pretty constant at 5.04V. The following code is supposed to print out the second digit of the temperature and show it on a seven segment output. I followed the same procedure to get the first digit and it worked. However, this particular one doesn't seem to work..

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

uint16_t readADC(uint8_t channel) {
    ADMUX = (0xf0 & ADMUX) | channel;
    ADCSRA |= (1 << ADSC);

    while(!(ADCSRA & (1<<ADIF)));
    ADCSRA|=(1<<ADIF);
    return(ADC);
}

int main(void) {

uint16_t sensorValue;
double voltage,tempC,c;
int tempInt;

// Common Anode Configuration

int lookup[10] = {
    0x3f, 0x6, 0x5b, 0x4f, 0x66,
    0x6d, 0x7d, 0x7, 0xff, 0x6f
};

DDRD=0xff;
PORTD=0b00000000;

//Set up ADC
ADMUX |= (1 << REFS0);
ADCSRA |= (1 << ADPS1) | (1 << ADPS0);
ADCSRA |= (1 << ADEN);

while (1) {
    sensorValue = readADC(0);
    _delay_ms(1000);
    voltage= 5.04/1023.0*sensorValue;

    tempC=(voltage*100-273.15);
    tempInt=(int)tempC;

    c=(tempC-tempInt)*10;
    onesPart=(int)c;
    PORTD=lookup[onesPart];

    }
    return (0);
}

The temperature here is about 31 C right now. The second digit is 1 but the readings are quite misleading. Sometimes it shows 2, 3, and even 7 or 8! I don't know what's the problem with the code.

I use Atmega8a's built-in ADC. It has 10 bit resolution so it does have enough precision. The analog input to ADC0 was 3.04V, resulting in a temperature of 304-273=31 C. The second digit is expected to be 1 not something else. Since it's the first time I've used ADC I might have got something wrong. Any thought is appreciated.


texts:
It looks like something internal has leaked (perhaps the capacitors?) and ruined my stereo. Is that correct? If so, what would cause that to happen? Or is the yellow stuff just some kind of insulating glue and the issue elsewhere?

Is there anything I can do to fix it?

I'm just curious and would like to know why my stereo has broken.


texts: How much applicable is raspberry pi at industrial point of view?

texts: As a student I have to design a project for automation of greenhouse. I can use single board controller as Arduino or I can use Raspberry Pi as well. I understand difference that one is microcontroller based and another is CPU based board. If I talk in terms of industrial application what experience will give me a better skill from perspective of industry's demand.


texts: Can an opamp be used in a 75MHz narrow band pass filter?

texts: My exposure to EE is more than half a century old (sorry). I want to investigate the near-field pattern of a variety of antenna configurations at 75MHz. I have purchased an AD8307 broadband detector power meter. I intend to feed that from an array of simple dipoles (quarter wavelength = one meter). The receiving antenna will be an identical array. I am interested in inserting a narrow bandpass filter between the receiving antenna and the detector to minimize stray noise effects. An opamp active filter looked promising until I tried to find one that would be appropriate for 75MHz. The highest gain-bandwidth product that I have found for an opamp is 20MHz. I assume that means that an LC passive filter is what I need. Should this be the series version with the lowest inductor resistance that I can arrange?


texts: I'm trying to use a single 24VDC power supply but rig it to give a heating coil the equivalent of 24Volts but at +12/-12 in reference to ground for safety reasons.  Is this as simple as a voltage divider with a high value resistor to ground?  Would that work or just kind of short out the supply?  Is the negative terminal of a power supply normally connected to ground or is it floating?  Let me know if there's a cheap, simple way of accomplishing this aside from buying two 12V power supplies or one that outputs +/-12VDC.  Thanks.


texts:
I am working on VFD for single phase induction motor. I am rectifying AC 220V directly to DC link capacitor. There is no LC filter from AC mains. There are harmonics in the AC mains. Can you suggest me a good way to design AC main filter or recommend me a filter that I can attach directly to my VFD to remove the harmonics?

  I have used the LC filter and LCL filter to check the response of the applied filter.
Value of the components are  C= 56uF  (AC capacitor)
                             L= 2mH   ( yellow iron powerder core)

I am want to know which type of core must be used, what will be the cut off frequency for this AC main filter.

The components that are appeared with my filter are given below.


texts: What are the key differences between Tantalum and Tantalum Polymer capacitors?

texts:
I've noticed that most component retailers split these types, and am wondering what comparative differences there are between them. I know that "regular" tantalum caps usually use MnO2 as an electrolyte, whereas polymer ones use (generally unspecified) polymers instead.

What are the main performance differences between them? Is there a key factor that should decide which type is used in a specific design scenario?


texts: Complementary MOSFET symbol in Multisim(Electronics Workbench)

texts:
It is just me or symbol for complementary mosfet pair in NI Multisim is wrong? And actually not just the symbol, but the function itself - it doesn't work as it is supposed to(or it's just me being stupid).
Here's the deal - the P-channel mosfet(top) is mirrored vertically, making its drain connected to Vcc, hence the internal diode starts to conduct and the whole thing doesn't make sense anymore. To provide evidence you can see the pin numbers and their meaning in properties.
I also tested it with simple circuit and yep - it doesn't work like it is meant to be.
Also the third picture is usual mosfet driver configuration.
So, questions are:
1) Maybe I don't get something and sometimes people put the P-channel mosfet another way around for some purpose?
2) Is it a mistake from developers and bug report should be written to NI?


texts: How to generate IP cores with access to hardware in vivado

texts:
I am looking for some guide on how create an IP-Core in Vivado which make integrate the hardware. I want to create a IP-Core which should act as an driver for VGA port. The problem is how to create it such that it auto connect to the right port, and how do I declare which ports it has to be connected to?

The board I am using is a ZYBO which has an Zynq 7010 processor.


texts: Reducing the offset voltage of a source follower

texts:
I am currently trying to reduce the offset voltage of the circuit attached below to less than +/- 2mV over a 1V to 4V input range.

I have a few constraints for this task:

I can use nmos, pmos and pmos4 but can't use nmos4 as the fabrication process does not support separate bulks for NMOS transistors.
I cannot use controlled sources e.g (vcvs,vccs,ccvs,cccs) except when calculating Voffset
I can only use one Vdc for Vdd and one Vdc for Vin and use only idc for biasing
Use at least 100nA bias current in all transistors

So far I have tried adding cascodes to the circuit to reduce this offset voltage but no luck. I would really appreciate it if someone could point me in the right direction regarding this task. Thank you.

Voltage Follower Circuit:


texts: How to get signal out of Geiger-Muller tube?

texts:
I am building a nuclear random number generator using an LND-712 Geiger-Muller tube (GMT). I have built a HV power supply circuit that converts the 3.3V output of my Adafruit Feather RP2040 micro-controller to the 500V needed by my GMT, you can see this circuit below:

The GMT that I am using has a recommended anode resistor of 10MegaOhm and a recommended signal circuit shown below:

I have set this up and cranked the power supply to the 500V operating voltage, but I can never get an output voltage from the 50pF capacitor to be more than 150mV from background radiation. I hooked it up to an oscilloscope and I can see the 150mV pulse so I know the GMT is working. The problem is that a pulse of 150mV is not high enough to trip my pulse generator circuit shown below:

Because it can't generate a 0 or 3.3V pulse my microcontroller is outputting a constant stream of 1's which makes for a pretty terrible random number generator. I'm planning on using strontium 90 as my radiation source which has beta decay with a energy of 546 keV, maybe this will increase the amplitude of my pulses as compared to background radiation. I'm not sure. I'm a mechanical engineer by trade so if I am doing something stupid with this circuit please let me know.


texts: Low power, cheap, long timeout, watchdog circuit

texts:
I need a circuit to act as a watchdog to a micro (which is not powered (instead of in a sleep mode)most of the time).

it needs to be low power (< ~4uA) and non-programmable. So no I2C RTCs or MCUs.

I've looked at RC timers combined with a comparator but extremely large resistors and caps become too expensive for the timeout required (25hours).

I've also looked at using shift registers to divide out an astable multivibrator to the correct time, but ICs (counter/dividers/flip-flops) i've been able to find draw too much current - ~8uA alone.


texts: how to modify a taper charger of lead-acid batteries to be a constant current charger?

texts:
I have a huge, cheap and dumb battery charger which can charge a 12 V lead-acid battery with 70A, but it only outputs anything near (by "near" I mean over 30A) that value if I give him a completely empty, dead battery. As soon as it starts charging it, the current drops, quite quickly well below 20A, and most of the charging is done at about 10A, in fact it decreases linearly all the time. AFAIK this is called a "taper charger" and is the cheapest, most dumb lead-acid battery charger common on the market.

The battery I want to charge has in the specifications that you can charge it with a maximum of 38A in the "Constant Current" phase of CCCV charging, in which 80% of the battery capacity can be filled. I want to modify my cheap charger to actually do that - to charge with a constant current of 38A up until the voltage at the battery terminals reaches 14.4V, and then just turn-off (I can do this manually, I won't leave it for unattended charging anyway).

Any idea how such cheap taper chargers are commonly made, and what could be done to modify one to a constant current charger?


texts: Distortion in the output of amplifier circuit using uA741 + schematics and graphs

texts:
I'm simulating an audio amplifier with uA741 in pspice (student version).
The input signal is a 0.1v (100mv) sine wave with frequency between 1kHz and 10kHz. The theoretical gain is 33 but in simulation, the gain of output is only 3 and we have DC shift and distortion. The slew rate is 0.5 v/us and if we calculate the max slew rate needed for my input signal using the formula below, we get a value much smaller than slew rate of uA741.

slew rate = 2 PI x f x Vpk /10^6 = 0.006283 v/us
http://en.wikipedia.org/wiki/Slew_rate

So the problem is not slew rate. When I replace the uA741 with "OPAMP" in pspice (which is ideal opamp) there is no distortion in the output. What do you think is the reason for this distortion?

Here are the schematic and input(red)/outputs(green) graphs:


texts:
This is my first attempt to simulate a circuit in the time domain with CircuitLab. In order to ask a proper question about something similar driven with PWM, I'd like to add an adjustable duty cycle to the square wave, and then if possible ramp it.

How can I add variable duty cycle PWM to a CircuitLab simulation within a question?

simulate this circuit – Schematic created using CircuitLab


texts: Power multiple 5V/12V devices off a single transformer?

texts:
I have these devices in my cabinet (Q-Panel) that have these power requirements:

21V 1.2Amp
5V 500mA
12V 1.5A
12V 1.5A
48V 1.25A

Obviously I can't do much about #1 and #5. I want to be able to have a single transformer/adapter and power #2, #3 and #4 off from it.

Is there anything that is a single transformer/adapter that allows you to pull multiple lines from - ideally that can be switched to 5V or 12V so that I can power all 3 devices from the same block instead of having 3 warts in my cabinet I could just have one?

EDIT: #5 is a POE injector. Can I just pull a cable off from this and use the power wires and just splice it into the plug? It says 48V - will the device automatically step this down, or does that only work for POE specific devices?


texts: Are direct coupled audio amplifiers still produced?

texts:
I am searching for an inexpensive option to drive a magnetic coil with a frequency in the range of 1 Hz to 1 kHz. DC audio amplifiers, such as a Crown 300A-DC Series II or a Mitsubishi DA-A15DC, are perfect for this purpose.

However, is there still any company producing these devices? Or are there alternatives for driving an ~8 ohm inductive load in the given frequency range with up to approximately 300 W power?

Note that I don't worry about drift since my system is feedback controlled by measuring the magnetic field.


texts:
The no-load current of a transformer consists of two components:

The Magnetization Current iM is the current required to produce the flux in the transformer core.
The Core-loss Current ih+e is the current required to make up for hysteresis and eddy current losses.

This is what my book says for the no-load current in a real transformer. To me it sounded silly that the magnetization current, which is a part of the overall no-load current, is solely responsible for the entire flux generated in the core.
How is it that not the overall but a part of the no-load current is responsible for all the flux that is in the core?


texts:
I am designing a system with multiple remote devices connected to a central hub, supplying low voltage DC power and RS-422 data. I plan on using RJ45 connectors, and am wondering if ethernet devices that accidentally get plugged into the 'Hub' would be damaged by low voltage DC across two of the RJ45 pins.
I believe ethernet devices have 'magnetics', would this protect against this?


texts: Determining the surge duration of a double exponential transient?

texts:
I am trying to calculate the maximum single peak pulse power rating of a thick film resistor that will be subjected to a significant amount of inrush current upon each power up.

The datasheet has a nice plot of maximum power vs surge duration for each package size on page 2, but I am struggling to determine the appropriate way to determine the surge duration of my transient.

The transient has somewhat of a double exponential shape, what interval would typically be considered the pulse/surge duration of a waveform like this?

My particular transient has the following timing characteristics:

t_1 = ~5 ms (rise time to peak value, 0%-100%)
t_2 = ~15 ms (cumulitive time to reach the 50% decay point)
t_3 = ~95 ms (total time until transient is effectively 0 again)

I feel like I remember learning that you measure out to the point at which the amplitude has decreased back down to 50% of the maximum, so in my case, 15 ms, but I can't find any sources online that back that up.


texts:
I am analyzing following circuit, but I am not getting its flow.

In the following schematic SW1 is coming from controller and connected to opto coupler ( cathode of LED ) and J4B is connected to heater.

Please explain me its operation and when Mosfet will conduct?


texts:
I designed a board and I want to have two ways of delivering power to it. Smooth failover would be nice but is not a goal. The main focus is flexibility. Here are the requirements:

Primary power: can be any fixed voltage, preferably 5 or 12V, not more.
Secondary power: anywhere between 5 and 24V depending on use case.
If primary power is present, it should be used. Otherwise secondary power should be used.
Worst case the board should run from 5V secondary power.

There's a power block on the board that accepts up to 30V so no need for voltage regulation. OR'ing diodes could be used but that would violate priorities if secondary voltage is higher than primary. Unfortunately I don't know enough about power circuits to design this. I would like to avoid using ICs if possible. MOSFETs seemed promising, but couldn't figure out a way to accomplish this. I appreciate any ideas, pointers, tips&tricks.


texts: Using audio isolation transformer to clean power to a Raspberry pi

texts:
I want to "clean up" the powersupply to a raspberry pi that I am using for audio recordings.
I am getting a lot of low frequency buzz, i.e. 60 to 2000 hz.
I am wondering if I can use an 1:1 audio transformer to reduce the interference from the PSU to the pi, alternately to isolate the usb-soundcard power that I suspect may also be culprit.
The pi PSU is 5.1v 3A
THis is the transformer:
Max voltage: 100V

Isolation coil+coil: 100Mohm min
Dämpning Dampening: 2.5dB max (1kHz)
Primary impedans (1kHz): 600ohm ±5%
Secondary impedans (1kHz): 600ohm ±5%
Primary DC-resistans: 50ohm ±5%
Secondary DC-resistans: 60ohm ±5%
Primär induktans (1kHz): 310mH
Sekundär induktans (1kHz): 330mH
relationship: 1:1

(please excuse my poor translation of technical terms)
EDIT
From what I have gathered in many posts poor power supplies(PSUs) can give interference in auxiliery equipment plugged into the Pi, e.g via USB or GPIO.
As for audio the answer to this post gives an example of a homemade PSU that provides "clean" power to the RPI to improve sound recording. However, this is takes a little too much space for the project I working on (networked wildlife cameras). Theoretically using powerbanks should be better than regular PSUs but powerbanks have their own step-up or step-down circuits that I find give as much intereference.
What I am looking for is a simpler, "good enough" solution to filter power to either the Pi or the USB soundcard so that I can remove some of the noise in region I want, i.e. 50 to 3000 Hz. How can I create a filter from 50 to 3000Hz?
Is the culprit likely to be the PSU or the pi itself?
Should said filter be placed between PSU and pi, or between soundcard and pi?