texts: Arduino programming on Uno fails using USB download on Windows 2000

texts:
I have a number of W2K systems that we are trying to use to program the new Arduino Uno and Mega devices.  These boards now come with a USB connection, an upgrade from the prior FTDI.  I'm not able to download the Arduino code into the board from a W2K system

The supplied drivers are *.inf files that modify the standard USB driver that comes with Windows (in this case W2K)

I go through the process of setting the port, setting the device and doing the download.  The download fails, and the apparent error is that the PC can not communicate with the board.  I've checked the port, adjusted the baud rates, etc.  I've even moved the port number from a high port number (ie COM12) to a lower port (COM2) without any success.  I do see activity on the rec/xmt lights on the Arduino board, so some type of data is being sent and received.

I'm looking for:
Someone who has been able to download files from W2K to the Arduino
or
A way to shim inside the USB driver to be able to watch the traffic going up and down to the board so I can continue to debug this.
or
Some general tips for things to look at in the .inf file that need to be set/not set to make it work on W2K.

I know the boards work I've used them on a different set of XP systems. So I know to some extent the install is good and that most of what I have works.

Full dumps can be found on the Arduino forum.
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1291090110/
This is the information produced by the AVRDude program while it's trying to download the code.

It was suggested at stackoverflow that this be posted here.


texts: Relationship between clock speed and I2C bus speed

texts:
I have understood how the I2C protocol works. The I2C protocol specifies three modes, namely 100kbps (original speed), 400kbps (fast mode) and 3.4 Mbps (high speed mode). One thing I didn't understand is the relationship between the clock speed and the bus data transfer speed.

If you want to say send data on the bus at a rate of 100kbps, what should be the clock speed to be decided between transmitter and receiver?


texts: Reduce BT power consumption by dis- and reconnecting

texts:
This is a question which comes from a programmers perspective (so might be SO, please migrate then) but with an EE background.

I am trying to programmatically reduce the bluetooth power consumption between a cellphone (Blackberry Z10 featuring probably a Texas Instruments WL1273L Wireless Module) and a smartwatch (Pebble probably featuring Texas Instruments CC2564).

Apple provides some best practices where they suggest (see last chapter) to "Disconnect from a Device When You No Longer Need It". But still BT would be enabled and draw power.

Now on the other hand, the connection phase seems quite power intensive, so the question arises if keeping a connection (without sending data) is better than disconnecting and reconnecting if data is available. are the underlying layers similar to this TCP scenario?

Is there a sweet spot depending on the rate of new data?

I am using regular BT, but how would BLE compare, is it worth porting (if possible).

Unfortunately i dont have the equipment to measure the power consumption.

Also, there is no lowlevel hardware access to optimize or high level access on the BT device (cant turn BT on or off), so the options are:

connect to device and keep connection open
connect to device, deliver data, disconnect, repeat

The delay of having to reconnect is accepted.

I do minimize the amount of discoveries so on reconnect i try to connect directly to the device. What other considerations could be taken?


texts:
At least in KiCad, the footprints of through-hole pin headers have one squared annular “ring”, the other ones are round:

What does the square indicate?

(Also I’m wondering if there is perhaps a convention of connecting GND to it.)


texts: How to add a desirable phase shift in the input from 3-phase ac mains?

texts: I want to build a 12 pulse rectifier circuit. I know delta-wye or wye-delta transformers can be used to add phase shifts equal to the multiples of 30, but I don't want to use transformers. Is there another way to generate the needed phase shift?


texts: Op-Amp and MOSFET current source not behaving as expected

texts:
Based on the circuit from this page called transconductance amplifier, I decided to build an adjstable constant current source for up to 1.6A:

Current is set by the voltage divider connected to the op-amp input: Iout=Vdiv/Rlim

On Multisim it works fine, however, in real life the current keeps drifting from this value, and the 5k pot does nothing.
I tried swapping the op-amp inputs and then the current starts high, slowly going down to the desired value, but in both cases the FET is heating too much. Is this design correct?


texts: What is the difference between Timer0 and Timer2 in AVR

texts: I'm using ATmega32. This two timers looks very similar. What is a difference between them? When should I use Timer0, and when Timer2?


texts: ac signal detection and output high or low

texts: how to make circuit to output high(1) or low(0) for microcontroller depending upon whether there is ac signal or not. the ac signal amplitude is between 0 to 5V. it is not AC main line signal.


texts: Measure LPG (LP Gas) level using an ultrasonic sensor. Which sensor?

texts:
I need to measure the liquid level of LPG through a thick 4000/8000/45000 stationary tank. They already have flowmeters but they are easily tampered. I need to be able to know how much Gas is in the tank (1% tolerance). I found some ultrasonic sensors Online that are designed to work with thick LPG tanks (at least they say) but they do not answer my emails and I was not able to source them.

Does anyone have experience with these sensors? Does anyone know of a sensor that works for such tanks?

If there is some other tamper proof method I could also use that. The floater sensing method is easily tampered so it's not an option.

Thanks.


texts: Comparison of two configurations to balance source impedance

texts:
This is a generic question for about frequency sensors. But as an example I use this sensor which has around 1k output impedance. So in below drawing the source in dashed box has 1k output impedance:

simulate this circuit – Schematic created using CircuitLab

The voltage signal from the source to the receiver will be transmitted by STP cable.
And the receiver is a sort of differential input instrumention amplifier.

But the system is not 100% balanced because of the 1k output impedance.

I think the best way is to buffer both signal and ground of the output for balancing but this would introduce some noise.

Assuming GND has very low impeance, In Figure 1 the 1k is lowered by a buffer.
And on the other hand in Figure 2 the imbalance issue is tried to be solved by adding a 1k resistor on the ground output.

My questions are:

1-) If I use a resistor as in Figure 2, then I would increase DC error but I can calibrate it out.
In that case can we say that Figure 2 is a better solution than Figure 1?
I'm asking because in Figure 1 the buffer circuit will introduce noise.

Which one is better than the other?

2-) Would you measure the exact value of the output impedance or would you rely on the datasheet?


texts: How to PWM a load regardless of the direction of current?

texts:
I'm helping a student at our art academy with an interesting project. She is building an array of peltier elements (let's say 25 to start with). She wants to control them individually using PWM and be able to switch the polarity on them every now and then.

We are aware this is a terrible idea in terms of thermal stress and the life expectancy of the elements, but we'd like to try it anyway for the sake of this project.

We could do it with an H-bridge for each one of the elements, but that would take a lot of work and components. I was thinking that we might be able to simplify it. Would it be possible to use four relays to reverse polarity on the power supply side, and then connect the peltier elements with optocouplers or something to do the pulse width modulation? That way, for each heating element we only need one component (which we open and close from an Arduino with a shift register), instead of a whole H-bridge module or four mosfets for each.

Which component would be a good fit if we want to send 12V @ 1 amps (peak 3 amps) through it? At first I thought a MOSFET like IRLZ44N would work, but they only work in one direction I think, with the source connected to ground. Would something like the TLP175A enable us to PWM the elements even when the direction of the current reverses?

Thanks for any advice!

EDIT

So I was thinking of something like this:

But this has the problem that the MOSFETS will not work with the current in both directions. So I was thinking there would be an alternative component that would.


texts: How to power from among several sources and monitor which sources are active?

texts:
I have a microcontroller circuit that uses voltage dividers to monitor presence of 5V DC power from several sources, but the circuit is currently powered from a separate 5V DC source.

I've seen Schottky diodes used to control power from multiple sources, but typically when they are at different voltage levels (e.g., a switching supply and a battery).

Questions:

How is reverse current from the Schottky diodes not a problem to the other supplies in the traditional use case?
Can Schottky diodes be used to direct DC power in cases where the supply voltages are all the same?
If yes to #2, is there a simple setup to power the circuit in this way and monitor which supplies are active (connecting to typical MCU GPIO digital input pins)?
If no to #2, what is a simple and cost-effective way to power from, and monitor, several similar sources?

EDIT: I don't need to know which (or multiple) supplies are powering the circuit, I just need: (1) stable power to the circuit, and; (2) to know which of the sources are active / powered on.


texts:
What is the required pad diameter for the following part ?

HM2J07PE5118N9LF

Maybe its late and I'm just not seeing ? The recommended PCB hole layout usually contains this information but I just don't see it.


texts: Can a replacement iPad screen be used on a BeagleBoard?

texts: I have been trying to find a good touchscreen with multitouch support for the BeagleBoard. I have not had much success, but have noticed that iPad replacement screens are available fairly inexpensively. Is it possible to use one of these as the display/touchscreen for a BeagleBoard?


texts: Synchronous DC-DC converter and fast diodes

texts:
I'm a bit at a loss when trying to optimize a DC-DC converter (Half Bridge) and selecting my MOSFETs.
Up to 200V I get good results (MOSFET switching times are fast ~ 20ns and the anti-parallel diode is really fast as well - Qrr is less than 1 uC). For higher voltages the MOSFET may still switch really fast ~ 20ns, even though the anti-parallel diode is bad: Qrr in the order of 20uC or even more. This causes very high switching losses at say 20kHz (well - at any frequency - but at around that frequency they become important when compared to conduction losses).

Now for the question: at high(er) voltage(s) the anti-parallel diode is bad in switching (Qrr high), even though its forward voltage drop is usually quite good (less than 1V sometimes). I don't really care since I want to use a synchronous converter (using one MOSFET in reverse conduction mode).
Should I put a fast (with low Qrr ~ 0.3 nC, but with a higher forward voltage drop) diode in parallel to the MOSFET, what would happen? Would the integrated body diode still switch on because of lower V_F (even though this would happen after the fast diode switched on) or could I take advantage of the additional diode's switching speed and short-circuit it with the MOSFET just a few ns after before the body diode could turn on?

Basically: would the slow (but with "good" conducting properties: V_F low) body diode of the MOSFET still turn on even though a fast (but with "bad" conducting properties: V_F higher for the same current) diode is in parallel to it?

I hope my question was clear. Feel free to ask other details if you need them.
Please link / cite any useful documentation if possible.

Additional thoughts: since the body diode may start switching (anyway) when the external diode is already conducting (having therefore a voltage drop lower than say 2V), the body diode would cause very low energy losses because the blocking voltage for it is now 2V, not the (say) 200V when the external diode was blocked. The additional switching losses caused by the unwanted turn-on of the body diode may be nothing worth to be considered. Right?


texts: What is the difference between intrinsic gain and just "normal" voltage gain of a circuit i.e Vout/Vin?


texts: Need suggection on spliting the power plane in a 4-layer PCB design

texts:
I am now dealing with a 4-layer PCB design. One of the internal layer is 3.3V power plane. As my circuit contains the sensitive analog part and the middle-frequency(about 100MHz) digital part, I want to split the 3.3V power plane to avoid noise crosstalk. Here is my two designs of how to split it:

Figure 1: split the power plane into two parts and place the regulator in the digital power plane.

And

Figure 2: split the power plane into three parts. The analog 3.3V power plane and the digital 3.3V power plane connect to the regulator power plane with FB-C circuit.

The second design seems to be better as it isolates both the analog and regulator from the noisy digital circuit. However, the circuit would be more complicated and more components are required. Is it worth?

Additional: the other internal plane is the completed ground plane.


texts: What difference a change in hertz vs duty cycle make to the pitch of a sound?

texts:
For example, 100 hertz sounds very low, but acquiring that from an online source that doesn't tell me the duty cycle doesn't answer my inquiry into whether a change in the duty cycle will affect the pitch of the sound. Will a 10% duty cycle sound deeper than an 80%?
Keep in mind, I'm 13 and just getting into Arduino programming (current project: piezo from the manual projects given). Thank you.


texts:
Which camera module will interface with STM32F7 Disco board? The connector on the board is a 30-pin FPC/FFC 0.5mm.

Could the OV2640 be adapted for this?


texts: What frequency and voltage should the electrical outlet have in order to be the least harmful to humans and still be useful to modern appliances?

texts:
Studying electronics a few years back I came across a graph like this one:

Showing that 50-60Hz current that is by far the most popular power coming from the electrical outlets in homes everywhere is among the most dangerous currents to human bodies out there. That got me thinking - what would be the safest frequency and voltage that could be used in our wall sockets while still being useful for modern appliances and home infrastructure?


texts:
I have been doing a lot of reading on trying to match constant current drivers to series of LEDs but either my calculations are incorrect or the demands of what I am proposing are way off the charts. This is part of a project to make a strobe light.

I would like to run 5 LEDs in series, here are the specs of each individual LED:

wattage:20w | foward voltage:30-32v | forward current:700ma

The ideal would be a driver with a fair amount of leeway, so that I could work with fewer or more LEDs, depending on the situation.

I know that all the questions on this topic must be driving you guys crazy, but there is so much contradictory information online, and it is hard to calculate with any confidence. So, if someone could tell me exactly what I need from a driver, I would be very grateful.


texts:
I am a novice when it comes to electrical engineering and I have a very basic question concerning the operation of RS latches:

I am currently working my way through Roth/Kinney's Fundamentals of Logic Design and I have some problems understanding the part describing the operation of RS latches. The book gives this table for the states of RS latches where Q^+ = R'S + R'Q and P = S'Q' and the stable states of the latch are circled:

Now, how comes that for SR = 01, Q = 1 and SR = 10, Q = 0 the latch does not end up in a stable states. I thought that that as long as SR != 11 the latch always ends up in a stable state.

Also, for SR = 11, Q = 0, how can the latch end up in a stable state. I thought that setting SR to 11 is forbidden and the latch state is undefined for this input combination.

Can anybody clarify that for me?


texts: 7-segment output: 4-6V, LCD input: 3-5V. How to convert?

texts:
Problem:

I am thinking of using a chip that gives out 4-6V on 7-segment output
pins but the LCD only wants 3-5V input, so I need to convert somehow.

The display is a TN type, drawing virtually no current.
The LCD data specification is tiny and poor and does not
actually mention current consumption, but a similar device's
spec mention max 2 µA/cm2, and the screen is 4 cm2.
Since that is for the whole device, it is approximately 0.3µA per pin
(8µA / (4*7)). (Are my assumptions flawed here?)

The solution have to be cheap since it should be applied to 25 individual
pins, and also preferably also not take up a lot of space.
One obvious, simple solution is to use a resistor voltage divider (10k +
47k would transform to 3.3-4.9V).

Do I have any other option?

My first thought was to put a diode (or two) in series, but that will
not work because the voltage drop over the diode will not be that great for so low currents, right?

Since the LCD will draw so little current, would there be any problem
using 100k + 470k instead of 10k + 47k?

Or can I just skip doing anything and feed the signals directly to the LCD, hoping it will be ok?

Project details:

Building a combined voltmeter/ampere meter similar to this and this, but using an ICL7106 instead of ICL7107.

Device specs: ICL7106, display (similar display).


texts: ADC for measuring 0-5V but connected to 3.3V device

texts:
I have a BeagleBone (BB) and want to connect the analog output of a motor controller to it. The motor controller creates an output in the range of -4V to +4V and the BB anlog inputs only accept voltages between 0V to 1.8V (digital  pins run at 3.3V). I only have a comparably small limited space of perfboard available, but 4 motors to monitor. I can provide 5V and 3.3V supply and 1.8V ref Voltage.
Here are the options I found so far:

Make an op-Amp circuit to convert [-4..4] to [0..1.8]. Probably a nice way, because I could use directly the BB-ADCs, but I am not to confident with these circuits (I found this example) and I would need one for every input which seems to be to many parts/space.
Use an ADC and connect it via I2C: The Max127 seems to provide exactly what I want. Single 5V supply, analog input range between [-5..+5] and I2C interface. I would really like to use this one, the only problem I have is that according to the data sheet digital high is seen as 0.7*Vdd = 3.5V. I do not now if 3.3V would be detected correctly (anyone has experience with that?). Pulling up to 5V is not possible as the BB is not 5V tolerable.
The Max1270 is basically the same as the Max127 but with SPI-interface. There the data sheet states the digit high threshold is 2.4V. I know that the I2C slave only pulls down. How does it work with spi, because the data sheet mentions digital outputs voltages (which are Vdd)?
Lose some resolution and only use the output range from [0..4]V. That gives a larger variety of possible unipolar ADCs, but most of them have the same limitation with 0.7*Vdd for digital high signals.
As in 4. But use ADCs with 3.3V supply voltage which have a range of [0..5], but I could not find any with 4+ channels.

I believe that I somehow going in circles. Does someone know a viable solutions or how to address the mentioned problems of (at least) one of the above described?
I would generally prefer through hole parts (as it's perfboard) but I could probably get some small breakout boards for SMD-devices as well.


texts: Why i'm facing this error (no declaration matches use as "xnor")?

texts:
I'm new to VHDL and i'm following a YouTube tutorial to learn VHDL. The instructor wrote this code and it seems to work with him but with me its not working.

library IEEE;
use IEEE.STD_LOGIC_1164.all;

entity gates is port (
    a : in STD_LOGIC ;
    b : in STD_LOGIC ;
    z : out STD_LOGIC_VECTOR(5 downto 0)
    );
end gates;

architecture arch of gates is
begin
    z(5) <= a and b;
    z(4) <= a nand b;
    z(3) <= a or b;
    z(2) <= a nor b;
    z(1) <= a xor b;
    z(0) <= a xnor b;
end arch;

When i try to compile it i get this error message

gvhdl: FreeHDL root path is '/usr'.
gvhdl: executing '/usr/bin/freehdl-v2cc -m Desktop/vhdl/new._main_.cc -L /usr/share/freehdl/lib   -o Desktop/vhdl/new.cc Desktop/vhdl/new.vhdl'
Desktop/vhdl/new.vhdl: in gates(imple):
Desktop/vhdl/new.vhdl:18: no declaration matches use as "xnor"(std_logic, std_logic), candidates are
/usr/share/freehdl/lib/std/standard.vhdl:5:  "xnor"(BOOLEAN,BOOLEAN) return BOOLEAN (invalid 0)
/usr/share/freehdl/lib/std/standard.vhdl:6:  "xnor"(BIT,BIT) return BIT (invalid 0)
/usr/share/freehdl/lib/std/standard.vhdl:69:  "xnor"(BIT_VECTOR,BIT_VECTOR) return BIT_VECTOR (invalid 0)
v2cc: Desktop/vhdl/new.vhdl: 1 errors
gvhdl: Compilation failed!
Died at /usr/bin/gvhdl line 211.

I'm using freehdl


texts: A very small microcontroller that can be programmed wirelessly

texts:
For fun, I'm building a microcontroller and a couple of sensors into a toy. The microcontroller must fit into a 2 cm wide cylinder. Also, removing it from the toy takes some time, so I'd like to be able to program it wirelessly. It doesn't matter how (IR, wifi, Bluetooth), as long as I don't have to remove it from the toy during testing.

I don't have much experience with these things, and so I don't know what to search for or if such a microcontroller even exists. What would you suggest?


texts:
I’ve been baffled about this for years. Why is the hardware design industry pushing so hard on the use of axi bus for communicating with cores and peripherals that don’t gain any advantage from its use in an FPGA?

What’s the advantage of using axi bus over a more signal efficient buses? Even axi lite seems like overkill most of the time. I could guess if you are close to the cpu pipeline running at 3 GHz that maybe you have to use something like that? but I have yet to find an fpga from Xilinx or altera that runs even 10 % of that rate and yet there’s the axi bus requirement for all of Vivado IP cores.

I look at Xilinx Vivado and I see axi bus every where with strange latent wrappers around more normal local buses just to translate it back to axi bus. I don’t know. It just all seems strange to me.

As a logic designer I really don’t have a choice to follow the axi convention when they already configure every core that way. Otherwise I would spend all of my time removing axi wrapper files.

I guess I’m just wondering what they see in axi bus that I don’t? Is this just some weird conspiracy to keep everybody busy wiring buses together and to sell larger more expensive FPGA’s that do exactly the same thing?


texts:
We have an SBC board, in the style of the Leopardboard or Beagleboard, that is misbehaving. It's based on the Leopardboard design (TI-DM368 CPU, DDR2 RAM, NAND Flash).

Developing software on the leopard all works well. However, the 1st prototype board turned up and refused to boot. Investigation lead us to the point where slowing the clocks (ARM & DDR) down means the board will boot.

The hardware (either board layout, termination, DDR chip, whatever) is the #1 suspect, as we can run identical software on the Leopard and it works fine. Unfortunately, the nature of the fault means we can't boot into linux to run strenuous RAM tests that may provide better diagnostics.

From the hardware side, the DDR clock is one of 345MHz, 486MHz, 680MHz depending on the clocking settings - beyond the scope of any of our scopes or logic analysers.

So - it's sort of two questions in one really:

From the hardware point of view, other than "rent a faster scope", is there an approach to diagnosing this with what's to hand? We have 200MHz DSO's, <100MHz logic sniffer, and 1.5GHz spectrum analyser to play with.

From the software point of view (I know, wrong forum) if anyone has tips or code snippets on exercising DDR RAM, they'd be greatly appreciated.

Edited to add the answer:

Well we borrowed a Tektronix 7104 and it worked so well we didn't even have to touch the board with it ;)

The problem revealed itself to be a sagging 1v3 power supply line being strangled by 0402-size SMT ferrites.

The symptoms were that, near the marginal operating frequency, the board would boot but lock when a memory-hungry / high-bandwidth video streaming process tried to start. This, coupled with the fact that running slower made it work OK, led us to believe it was a frequency-related issue when in fact the lower clock frequency was also putting less load on the power supply components.

The 0402 ferrite beads used for filtering were going surprisingly high impedance as the current went up, dropping a critical supply line below the allowable operating point.

Unfortunately this means I can't give the "winning answer" to Dave Tweed, but it does mean our board now works. Even better, it's the boss's fault not mine!

Oh and Tek 7104's are freakin' awesome feats of electronic engineering. If you've never looked at how they work, it's pure analogue kung-fu.


texts: Is RMS value of a pulse wave practically useful?

texts:
As we know the mean value of a pulse wave (depending on its duty cycle) corresponds to a constant DC.

But when it comes to alternating current through a resistor for DC power correspondance we measure the RMS value i.e. RMS of an alternating current becomes such as the current which lights a bulb as the same intensity as if we have a DC value of the same with that RMS.

I measure pulse wave voltage with Voltmeter's DC settings. I think it gives the mean value.

So my question is if we have a pulse wave does it make sense anymore to talk about its RMS value?


texts: What informations can we obtain with these voltage and current measurements of a little electronic device?

texts:
I powered a little electronic device with 2 AA batteries and here are the results measured with a multimeter:

When using a first set of 2 AA batteries:

Voltage when device unplugged: 2.45 V
Voltage when device plugged / ON: 2.10 V, consumption: 0.30 A

When using a second set of 2 brand new AA batteries:

Voltage when device unplugged: 3.10 V
Voltage when device plugged / ON: 3.00 V, consumption: 0.20 A

Just being curious: what informations can I deduce about the device or about the batteries with these measurements?


texts:
I have a composite PAL/NTSC video signal. One problem I am having is getting a reliable sync signal from it; picture brightness causes the sync pulse (normally 0.3V) to vary; so much that my scope won't trigger on it reliably (with the video trigger.) I've heard I need a DC restoration or DC clamp circuit, but I can't find any information on this, except occasional references in books and on the internet, but no detailed information. Does anyone know what circuit I need?

I have previously used an LM1881 or LMH1980 to extract sync because they build the DC clamp/restoree parts in. However, the problem with these chips is that they are expensive and often bigger than a discrete solution.


texts:
I need to control a heatgun temperature. My heatgun have two different temperatures, one about 300° and another about 400°/500°(something like that) with 2kW max power at 220v. I've connected a temperature sensor at hotgun output, and now I want to try to PWM a relay that is connected between heatgun and AC. Relay take about 4/5ms to change between ON/OFF.

My question is: What I can damage if I PWM a heatgun?

Of course relay will not survive many years, but it's cheap to replace. Can I damage home electrical system(lifeguard electrical system if name is correct)? or can I damage heatgun becouse maybe fan run slower and resistor overheat?


texts:
I am an amateur grower of Capsicum Cayenne Chilli and have been experimenting for some years with good results using Compact Fluorescent Lamps in a small indoor grow room, but I am now looking to experiment with the new LED technology.

The supplier of the LED’s tells me that in order to run these units I need to build a ‘current sink circuit’ that will run the LED’s slightly lower than their maximum rating, suggesting that I should ask the good people of the Electrical Engineering forum for advice.

As a sculptor with a good grounding in mechanical engineering I am practically minded so shouldn’t find the physical build a problem [soldering small components for example] but I know precious little about Electrical circuitry, circuit diagrams and components: in this regard I am a complete novice.

That being said I am always keen to learn a new skill.

My question then is:

How do I build a Constant Current Circuit in order to run a bank of 40 x 3 W LED’s [these will be in two separate strips of 20 LED] and what components do I need to purchase? [I am based in the UK]

Any help or advice, links to videos etc would be very much appreciated.


texts: I have connected a 3.7v-4000mah battery to a load via a voltage booster MT3608 (3.7V to 12V) . load current is 100ma. how long does battery can work?


texts: Reasons for Popularity of PowerPC for Embedded Designs

texts:
The question was asked before and is not active anymore, but I am not at all satisfied with the answer:

What's so great about PPC? There's gotta be something

According to David Kessner's answer, there were once reasons for PowerPC, but there are not any today.

While this may be true for desktop computers, it cannot be true for embedded systems. All three major gaming consoles use a PowerPC (Wii, Xbox 360, PS3). Microsoft, focusing completely on Intel at that time, even switched for their new Xbox from Intel to PowerPC in 2005.

Network devices feature in many cases PPC, many automotive microcontrollers do as well and there are still new PPC product developments (e.g. by Freescale). PowerPC's can in addition be found in the storage system, the medical, or industrial automation domains.

Backward compatibility (support of legacy software) is one driver, of course. But there have to be more.

Is it the high scalability and application programming interface compatibility within the PowerPC family, from small microcontrollers to processors for high performance computing?

The robustness of the design and experience with certification of functional safety?

Support of high temperature ranges, especially fan-less designs for high temperatures?


texts: HAL SCCB Commuincation via I2C: HAL_ERROR Status

texts:
I am using an STM32f4 Discovery board to interface with an OV2640 Camera.  When attempting to set the SCCB registers, I am using I2C.  However, when doing a simple test I cannot connect to the device. I have connected the VCC, GND, SCL, and SDA ports to the STM32 and the camera.  I am using the following code to check if I am able to connect to the device.

static void MX_I2C1_Init(void)
{

 hi2c1.Instance = I2C1;
 hi2c1.Init.ClockSpeed = 10000;
 hi2c1.Init.DutyCycle = I2C_DUTYCYCLE_2;
 hi2c1.Init.OwnAddress1 = 0;
 hi2c1.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
 hi2c1.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
 hi2c1.Init.OwnAddress2 = 0;
 hi2c1.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
 hi2c1.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
 if (HAL_I2C_Init(&hi2c1) != HAL_OK)
 {
   Error_Handler();
 }
 }

void OV2640_IsReady(void)
{
  HAL_StatusTypeDef status = HAL_OK;

  status = HAL_I2C_IsDeviceReady(&hi2c1, 0x60, 5, 1000);

    if(status != HAL_OK)
  {
      Blink_Orange();
  }
    if(status == HAL_ERROR)
  {
      Blink_Green();
  }
}

Each time I run this, the orange and green LEDs blink, indicating that I am receiving a HAL_ERROR when the controller checks the I2C device.  The slave read address listed on the datasheet is 0x60. I have tried modifying this address by attaching the R/W bit at the end (hex address changes to 0xC0) but this did not work.  As I understand, it should be very simple to connect to the SCCB interface as long as I have connected VCC, GND, SCL, and SDA.

What could be the problem with this connection?


texts: How to line a Metal Melter secondary for higher safety

texts:
A Metal Melter is a kind of home-made low voltage (less than 40 volts, mine is 3v) welder (small-scale) made from a microwave oven transformer (MOT). I left the primary intact (the thicker wire, which connects to house current), and replaced the secondary (the high voltage winding -- the much thinner wire) with 2.5 turns of 4 guage which I purchased from Walmart in the form of the thickest auto jumper cables I could get.  It's pretty safe already because the jumper cable insulation is very thick, and it works great, but if it overheats, the insulation might melt, so...

I want to make it as safe as I can make it.  I plan to add a fuse on the line side, ground the steel body of the transformer, add a fan, and also build a ventilated non-conductive enclosure for it.

In particular, I want advice on how best to line the secondary with robust insulation as described below:

The secondary is completely separate from the primary, in it's own slot, and I want to line the secondary slot with an approximately one-eighth inch thick non-melting insulator that would make it extremely safe. I was thinking of glass with Kapton on both sides to maintain its integrity even if it breaks or shatters. I could take a torch and bend the glass around the transformer corners before covering it with two layers of Kapton. So, is this good enough, and is there a better solution?

The transformer can get very hot, because of the low voltage (I'm thinking of increasing the windings and therefore voltage), so the insulating solution must withstand high temperatures due to accidental overuse of the transformer. That's why glass was my first thought. Thanks.

Here is a picture of one of my first tests with it.


texts: shorting behavior of isolation transformer

texts: I have a very expensive 500va 1:1 toroid transformer with to isolate workbench from ground. But I'm afraid to use it for fear the winding may burn up when something shorted. I'd like to know what is the behavior when the secondary shorts. Would it heat up faster than the primary winding able to draw current and tripping the primary breaker? What value must be the primary breaker, and can you use secondary breaker too (and what value)?


texts: how can i switch sim card clock signal line betweem two sim cards?

texts:
My setup is as on png above, I am using sim800L gsm module, by trial and error i discovered that i can connect sim pins: (rst,gnd,io and clk) and the module detects and connect to GSM without connecting power to sim vcc pin, i also read that sim vcc is optional.

what i want to do is somehow switch clk signal so that one sim card is detected by module at a time, i can do it with manual switch but how can i do it with electrical switch?. pls help.


texts: Are decoupling caps necessary for analog ICs (e.g. LM339, LM324...)?

texts:
Often 100n to 1µF decoupling caps are placed across IC supply lines for digital logic.

For analog circuitry, are decoupling caps necessary when the environment is also shared by microcontrollers and digital logic?

I have never placed them and haven't had any troubles, but I haven't made production stuff yet, so wouldn't have much experience.


texts:
I may have used these interchangeably without thinking, and did not have any problems.

always @(*)
  output = input ? a : b

or

assign output = input ? a : b

For a more nested case, the always block with if/else statements would be more readable, but other than that would there be the case when I should prefer one over another?


texts: Driving LCD segments with an LC generated sine wave to save power?

texts:
All of the LCD drivers I have seen use square waves to generate the RMS voltage across the segments. Since a segment acts as a capacitor, this seems to needlessly use coulombs to constantly charge and reverse the polarity by shunting to the supply rails.

Could it be more power efficient to generate the same RMS voltage using an LC oscillator where the glass is the C (or at least part of it)? There would still be R losses, but these could be significantly less than the losses of the digital drive.

Is there a reason why this is not done? Or is it done and I just haven't seen it?

NOTE: This would only apply to static segments and not multiplexed displays. I also know that the power requirements for the existing digital drives are already very small (nA's), but static LCDs are often used in extremely power and space constrained applications so any reduction of power could be worth it.


texts: Using Arduino Flora as a general purpose ID badge

texts:
I am a s/w guy, only just getting into embedded programming, with little or no knowledge of hardware .

I love the look of the new Flora wearable Arduino and would like to try a few simple projects to teach myself some new skills, maybe a new hobby.

With BlueTooth and GPS, I can see some possibilities as an intelligent Id badge. And here come my dumb h/w questions ...

1) could I add Wifi to this? Is it cheap and easy to do, both in terms of hardware and software?

2) what about RFID? I suppose I could just stick a passive Id tag on to it an leave it at that. But, can I attach an active RFID tag and have the MCU be aware that the RFID tag has been scanned by a read?

I hope that doesn't sound too dumb and thank you in advance for any help.


texts: Eliminating ghost voltage and breaking ground loops in a system

texts:
The above illustration is a setup I use where amplifier outputs go to a data acquisition system through BNC cables. The data acquisition system is earth-grounded. Mains system voltage Line to Neutral is 230VAC.

A1, A2, A3. A4 are force-transducer amplifiers(they output 0-10V DC signals) which are powered by an SMPS type 24VDC power supply(PSU in the illustration). As far as I found out there is a ghost voltage(when BNCs are not plugged/ when floating) between the BNC connector tips and the earth(marked as gray in the illustration) due to SMPS Y-capacitor leakage. This ghost voltage is 85VAC when the PSU is ON and 180VAC when it is OFF.

Even though this ghost/phantom voltage is safe due to microampere level currents, It causes a very unpleasant sensation. I want to eliminate or minimize it.

If I wire the DC GND of the PSU output to the earth the issue disappears, but then since the DAQ system is also earth grounded there will be ground loops.

My questions are:

1-) If I replace the SMPS with a linear supply, would the ghost voltage disappear? And if so, how can I be sure if the linear power supply I buy is 100% linear?

2-) In another forum, I read some suggestions which were wiring the DC output GND of the SMPS to the earth through a 100 ohm series resistor or using anti-parallel diodes. It was mentioned, one of these supposed to drain the leakage currents but break ground loops. Any idea about this work around and how to implement it?


texts: A program to add 6 bytes of data and store sum and carry in 8085 instruction set

texts:
I have a question on 8085 instruction set.
A program to add 6 bytes of data stored in memory starting from 4500h. must use b register to save any carries and finally store the sum and carry at two consecutive memory locations 3000h and 3001h.

I wrote the following for it.

ACI 4500h
ACI 4501h
ACI 4502h
ACI 4503h
ACI 4504h
ACI 4505h
STA 3000h
HLT

So, is this right and even if it is can you make some suggestions to make it better like make a loop instead of repeating ACI six times and so on.

Suggest any think that you think would help me learn more about this program.

Thanks in advance.


texts: What is the difference between 1N4001 and 1N4007 other than their maximum reverse voltage?

texts:
I compared 1N400x diodes here. As far as I see, all of their properties are same other than their maximum reverse voltages.

Their

maximum current
recovery time
reverse leakage current
capacitance

are the same.

It looks like 1N4007 is the super version of all other 1N400x diodes. So, why would one produce 1N4001...1N4006 diodes, and why would one buy them? If 1N4007 does the job alone, then why are the other versions still in the market?


texts: Why are input resistors in power supplies covered with shrink tubes?

texts:
Most small switch mode power supplies have an input resistor (typical 10 ohm) in front of the rectifier.

Mostly this resistor is covered by a shrink tube. The top wire do not have an insulation, so it can't be a safety precaution. Why is this resistor covered by a shrink tube?


texts: Learning how to build circuits using data sheets

texts: I'm 15 and trying to use an AD9952 DDS in my circuit. Up until now, there has been plenty of help online for the Arduino and corresponding parts. I haven't seen any schematics using the AD9952 and I don't understand the data sheet. I figure if I start with easier devices like the 555 timer, I could build my way up to using the AD9952. Is this an effective method of learning to build circuits and reading data sheets or should I learn another way?


texts: Voltage across resistor keeps the same as actual voltage

texts: Im a very beginner trying to learn some electronics basics. I am trying with resistors. I connected a resistor to a 12v power supply in series and tested the voltage using multimeter. But it keeps the same as the actual volage. No voltage drop shows with or without resistor. What could be the reason?


texts: What device to power 4 directional coils to rotate magnetic field

texts:
I am trying to make a solid state device that creates a magnetic field applied on an sample that can control the field direction and strength.
My current design uses a 8 coil stepper stator that has been rewired so that the opposite pole coils are connected and aligned such that when current flows through them, the field they generate sums. Then I can independently control the current through each pair of coils. (i.e. there are 4 circuits with two coils aligned opposite each other, aligned N, NW, W, SW). The external sample is placed inside the stator.
My issue is that to rotate the field in this solid state device, I need a controller (I'm using an arduino) to make each direction pair vary sinusoidally with an input angle from a potentiometer, which cannot output high current (I want max 2A), so I am outputting to 2 L298N driver circuits, where each driver controls the direction (+ or -) and magnitude (following sinusoid) of 2 directional coil pairs (there are 2 motor controls that I am using). This has mostly worked, but I have found out (thanks EE stack exchange, and my measurements being weird) that the L298N will not take low input voltages (aka there is a threshold) and has a minimum output voltage. It also does not create a current source.
By cutting off low voltages, the accuracy of the rotation is compromised and the summed magnitude is not constant while changing angle, this is important.
Is there a better device (than the L298N) that I can use for this purpose?
In summary:

produces positive and negative current correspondent to a input signal voltage from a controller
Needs to output magnitude of 0 to low to high current (max of 2A), but I don't care about voltage, (my coils have resistances of 3 ohms)
IDEALLY, are current controlled, but otherwise I could use a current sensor and my controller to keep it stable

Thanks!


texts:
I recently had a PCB designed which has several analog, digital, and power elements.  The board is powered by 24Vdc which is stepped down using an LDO to 3.3V and 5V.  These voltages are used to power the many IC and MCU on the board.  The issue I am having is when I touch the ground layer on the board to measure voltages with my multimeter a very intense voltage oscillation occurs.  This first picture shows the voltage spike on a 1 volt signal on the board.

This second picture shows the oscillation on the 24Vdc power line.

Some other pieces of information:

I first noticed this issue while debugging the MCU code.  I was verifying the DAC output and noticed when a single probe on my meter touched the board the debugger would lose connection.  Thus I used the oscilloscope to see this disturbance.

This phenomenon is very random when it occurs.  It is not instantly repeatable and when it occurs the amplitude of the disturbance varies.

We've used 2 different 24Vdc supplies and both create the same issue.

I've also recreated the issue using a stray wire as opposed to a multimeter probe.

My current thoughts:

I haven't provided the PCB layout because I don't need someone to solve this problem for me (although I will provide pieces of it if need be).  What I would like to know is what could cause an issue like this?  To me it seems that because it only takes a single open wire to create this issue, the stray wire is acting as an antenna or some sort of conductor for a massive discharge on the board.  The spike always starts with a voltage dip and it seems like it takes time to "recharge".  Let me know what you guys think about this.  I have seen grounding issues on a PCB before that cause signal integrity issues but never anything that cause the high voltage spikes.


texts: Charge distribution/movement in an insulator

texts: The way I understand it, net charge in a conductor spreads out evenly over the surface, while for a charged insulating object, the charge will tend to stay clustered around the spot where it was charged.  Still, even an object that's considered an insulator could still have some limited electrical conductivity which could allow charge movement at a slow rate.  Is there a way of calculating how long it would take for charge to spread out over the surface of an object with a given electrical resistance, surface area and net charge?


texts: What is the plug model to match a bm04b gh connector

texts:
I'm building a MEMs project using the omron D6T-44L, and the connector on it is so tiny I cant even solder tap on to the back.
I've searched and am having no luck finding the name of the model that will fit in to the bm04b gh connector.


texts: Load Resistor for high amp low voltage testing

texts:
I want to simulate a signal of 15V / 30A through a device.

I will use it to ensure that a series of prototypes are capable of switching at this current.

$$ P = 15 \times 30 = 450W $$

$$ R = \frac{15}{30} = 0.5 \Omega $$

To be on the safe side, (wire, etc., resistance), I intend to use three 1 ohm 225W resistors in parallel.  I have a power supply where the current can be limited, so will set the limit to 30A.

simulate this circuit – Schematic created using CircuitLab

It seems really straight forward as above but I wanted to make sure I hadn't overlooked something as I have not done this before.

Can anyone tell me if the above looks ok?


texts:
How can you safely build an uninterruptible power supply with Lipo batteries?

There are a lot of boards out there for connecting a charger to an external supply to build a UPS. However, all the Lipo chargers I've found charge cells up to their maximum 4.2V. I've found that unlike most batteries, Lipos become damaged if you keep them charged at this level for more than a couple of days.

For prolonged and constant use, Lipos can only be charged to 3.7V/cell.

Is this what laptops and cell phones do?

Is there any simple way to modify existing Lipo chargers to only charge to the "storage voltage" or would you have to design your own charger from scratch?


texts:
I buy an used notebook (Sony Vaio SVF152C29X), its only defect is that it doesn't charge the battery, it only works plugged in the power supply (19.5V and 6.2A output).

I don't know if the battery doesn't charge because it's dead or if it is a notebook defect.

I used a multimeter (in DCV position) to measure the output in the notebook terminal (where I plug the battery) and it shows 19V. But the battery specification is 14.8V/2670mAh/40W (it is a Sony VGP-BPS35A).

Is there something wrong with the notebook or it do exists batteries 14.8V that charges with 19V voltage? Or the battery can have a smaller transformer inside it?


texts: Is there a complete "donkey proof" method to discharge a HV-Capacitor?  There are several safety issues on leaving it charged where I go to school, since some students tend to tamper with anything I create, or make.  Hence, leaving out in the open is not ideal, since the HV-Capacitor will be charged when immediately after I use it.  Any advice on this safety issue would be desired.  The HV-Capacitor is attached to Jacob's Ladder?


texts: transimpedance op-amp wrong and random output

texts:
from my previous question (this link) i advised to using
    operational amplifiers to converting current changes to voltage
    changes then i followed the standard circuit for a transimpedance
    operation of amplifier with a piece of TLC272CP which you can see
    how i wired it :

my aim is measuring IR, so i connected a photodiode to the op-amp, i tried single supply because i cant make bipolar supplies +/-, then i create a virtual ground by simply dividing resistors to get a mid rail voltage between VDD(5v) and GND. then connect output (also divided) to an ADC.

unfortunately resaults from ADC are some random noises and IR does not affect them even a bit!!! they are near to 2.5 volt without output division.

also i disconnected +input of opamp (PIN3) from VGND and connected it to the physical GND but still sense less to IR, just get lower noises.

i think my circuit is just follow standards, so what could be wrong with it.


texts: Multiple signals requires multiple filters?

texts:
So, this might seem rather basic, but I'm going to pose it in the hope that I can save some work. So, I have a series of electrodes that are sensitive to voltage fluctuations, but, before I pass the data into the Arduino and then into the computer, I wanted to create a circuit that acts as a bandpass filter in order to reduce 60hz noise from appliances as well as to limit the read frequencies.

Though, I plan on using a good number of electrodes (either 16 or 32 as of right now) so, rather than running each individual electrode through a separate bandpass filter, is it possible to apply these filters by passing multiple electrode signals through a single or a smaller number of filters rather than having to build one filter for every input? Thanks in advance for any insight you guys can provide.


texts: How to change PIC watch dog expiration duration in run time?

texts:
In one of my application using PIC18F25K20, I set the Watchdog Timer Postscale Select bits as following for the CONFIG2H register at the beginning of the c code under configuration bits.
pragma config WDTPS = 1024    // Watchdog Timer Postscale Select bits (1024 * 4 mS = 4 SEC TIMER)
Now during run time in the code, I need to reduce the watch dog timer expiration time from 4 sec to 250mS. In order to do this, I need to change these WDTPS postscale bits in run time (only once).
Is it possible? If so, please advise how to do this..
What I am trying to do is as follow:
In one point during code execution, I want to put PIC in sleep. After 250 mS, PIC should wake up and do software reset using RESET instruction to reset the PIC. I don't have 555 or any other means to time this duration. No external interrupt would be possible as this is just software delay before RESET in sleep mode (to save battery power). I am using 20MHz external crystal and do not have any separate Timer 1 crystal for clocking in sleep mode.
So, I can only think of Watch Dog timer to wake up PIC after 250mS to perform RESET. Any other thoughts?


texts: Is there any offline circuit simulator software that can simulate a noisy power supply?

texts:
I have been using Circuit Wizard (Its the only offline program that I can find!). Unfortunately, it is really basic, and I have outgrown it.

I need to simulate a 5V circuit with a noisy power supply, with a lot of ripple/noise (anything from 0.1v to 1v). I am an electronics novice, and I have tried all sorts of things, like these:

And none of them work properly. I was wondering:

Is there a way to make this work at all?
Is there a good offline circuit simulator (as I do not always have internet access) that is easy to use, and can simulate noisy power supplies?

EDIT: I do not mind if the programs are freeware or paid.


texts: Two server powersupplies in a row dangerous?

texts:
I have two server PSUs from HP which can output 12V with 1200W (HP DPS 1200.) My goal is to obtain 24V by chaining the outputs of the two units.

I have modified one of the PSUs so that the negative output is no longer connected to earth by replacing one of the case screws with a nylon one, as recommended by threads in RC forums, where users use those supplies to power their battery chargers.

The metal case of both supplies is still grounded, so the only concern should be high voltages on the 24V output of the combined unit if something goes wrong inside the PSU.

One guy in these forums was concerned about the over voltage protection no longer working if this modification is done.

I want to know if such a modification disables safety features in events where the transformer is defective and shorts mains voltage to the low voltage side and if the order in which the supplies get connected changes this behavior.

(negative/earth side of the unmodified unit to 12v of the floating unit)


texts: I was required to draw a schematic diagram of inverting amplifiers using LM308 Op-amp in LTSpice. I need to connect +ve power supply to 10V and -ve power supply to -10V, a feedback resistor of 10k ohm and input resistor to set the gain to -10.I'm totally new to the op amp and LTSpice. Can i know whether im doing it correct or not?


texts:
I was searching around for batteries to use in my personal electric scooter project. I've found some LiFePO4 that has sufficient capacities like:

http://en.winston-battery.com/index.php/products/power-battery/category/lithium-ion-power-battery/1

But they seemed heavy and I found out that there is an alternative some people have constructed arrays from 18650 Li-ion batteries that worked for them. I am a bit of a novice when working with batteries. I don't know how hard or hazardous it is to construct the array myself and maybe it's just safer to buy them pre-constructed. So I've searched more and found these:

https://www.energusps.com/shop/product/li-ion-building-block-with-temp-sensor-3-6v-20ah-18c-discharge-37

These modules seem like a good solution for me, but I have never use them or something similar and can't find anything like reviews or forum posts about these are they worth the money? Have anyone tried something similar? What should I know about them ? Or should I just try making a custom pack myself?


texts: I have a mechatronics project where I have to use a push button switch at the input of A jk-flip flop my problem is when I click the switch it gives me the input 1 to the jk input the moment I remove my finger from the button it gets to zero. I want a way so that when I click the push button the input to be saved as 1 at the input of jk. I mean even when I remove my finger the input to remain 1 and get back to zero just when I click the switch again.


texts: I want to connect a PCIe 16x 3.0 GPU card to a Raspberry pi. I don't mind lo loose bandwidth, i just want to use the core GPU capabilities. So, the only idea that came out to my mind is to use the 26 GPIO RPi pins. I am concern about the GPIO/PCIe programing, do not have any idea neither an approach. Is this a crazy a idea ? can somebody help me to get a big picture of what i must to do ?


texts: (RasPi) Trying to control 2 different water pumps with different relays

texts:
PS: This is for a school project and I'm not very experienced with electronics.

I'm trying to create a flush system. I need to control 2 different motors, it's a single iteration circuit with a timer, so every time a button is pressed motor A and motor B will turn on, after a set time motor A will turn off and so will motor B a little later. I'm trying to do this with relays and a RasPi. However, I don't have to use these.

I have a :

RasPI 3
9V batteries (2)
SRD-12VDC-SL-C (2)
12V DC motor (1)
3V DC motor (1)

I want to ask will this circuit work? Or is there a better way to do this?


texts:
I am trying to repair a very expensive manlift joystick. I had great luck soldering in a new potentiometer on a different machine and getting it back to work, but this other machine has a potentiometer that I have not seen before.

It has 4 pins total, three like a normal rotary potentiometer and then a fourth across from the other three pins.

It is a Clarostat U-10K-OHM Type EJ pot. It has another number stamped "99148B 9507"

Clarostat has been purchased by Honeywell, so I am having a hard time finding any catalogs or datasheets for this guy. Can anyone point me in the right direction or advise what the fourth pin may be for? Would replacing with a standard three pin pot be a possibility?

Thanks!


texts: When sizing relays do you take into account the inrush current?  For example, if I have a load that draws 2.0A inrush and 0.75A afterward, do I select a relay that have to handle the higher inrush load?


texts: Specifications to consider when selecting a polyfuse

texts: I am designing a power supply for a flight controller, and I am finished with the regulating and almost everything else. I want to have a polyfuse on both of my inputs, but I don't know how to pick the right one. I don't really know much about the power consumption of the application, as it can vary. But, the maximum output of the power supply is 1A. the maximum input voltage should not exceed 22.5V. I know that things to consider in such a fuse is I_trip and I_hold, and of course maximum voltage and current. Can anyone explain I_trip and I_hold to me?


texts: What is the harm in applying too much current to the base of a NPN transistor when switching power?

texts:
Background: I'm using a NPN transistor (TIP-122) to switch power (digital, with PWM) to a ceramic resistor/heater. I'm trying to finalize the circuit and move it from breadboard to perfboard. I will want to periodically swap the heater. One heating element draws 0.58A (at 12V), the other will draw 5A (at 5V).

If I choose a resistor for the base such that the transistor is saturated and applying enough current for the high power heater, will it cause damage when used with a lower power output? Or is the base resistor only present to protect the signal input (which is only designed to supply a tiny current)?


texts: Implementing a polynomial voltage-controlled current source in LTSpice

texts:
I want to implement a voltage-controlled current source in LTSpice. The output current should be
$$I=a_{0}+a_{1}V+a_{2}V^{2}$$
I know I have to use the POLY element, but I can't figure out how to use it.
I am using LTSpice in macOS. Any help please?
Thanks in advanced!


texts: Is this the right approach to soldering really small wires?

texts:
This is my first time trying to solder some really small wires.  I'm going to try to solder this first end:

With this second end:

I removed the black wrap around the second end to fully expose the copper wires:

Because I've never done this before, I want to know if my following approach will be correct?

I am going to intertwine the inner copper strands of the red wire of the first end with the inner copper strands of the red wire of the second end.  Then solder.  Then apply a plastic insulator around the soldered area.
I am going to intertwine the outer copper strands of the red wire of the first end with the inner copper strands of the black wire of second end. Then solder.  Then apply a plastic insulator around the soldered area.
I am going to intertwine the inner copper strands of the white wire of the first end with the inner strands of the white wire of the second end.  Then solder.  Then apply a plastic insulator around the soldered area.
I will leave the outer copper strands of the white wire of the first end unconnected.

These wires seem so small to me that I feel like I'm going to mess something up.  But to everyone else, is this a very common soldering job?  I welcome insight on how best to solder these.

EDIT

These wires were previously connected.  But there was a problematic connection around the strain relief of the connection, so someone suggested that I remove the problematic area and re-build the connection.


texts: Filtering Capacitors before the fuse or after the fuse while limiting inrush current?

texts:
There are basically two questions I have for this circuit.

1) Which capacitor configuration is good? before fuse or after fuse

2) How do I limit my inrush current?

My thoughts:
I am confused between weather to put filtering capacitor before the fuse or after the fuse? Putting a capacitor at the IN (Voltage in) pin of the voltage regulator(LM1085) is recommended by LTC. According to me, if I put my cap after the fuse, it will act like a short when I connect my 12V PC supply to my board. The inrush current could kill my fuse every-time I connect PC-supply. To me putting a cap before the fuse make sense but still, I have a feeling it could still act like a short during inrush and harm my PC-supply. What I want is a nice filtering at the IN pin of my regulator while limiting my inrush current. The circuit powered by my regulator (U2) has max 300 mA loading. Any suggestion of what I need to do here?

Here is the datasheet link for my:

capacitor->
http://industrial.panasonic.com/lecs/www-data/pdf/ABA0000/ABA0000CE2.pdf

fuse->
http://www.littelfuse.com/~/media/electronics/datasheets/fuses/littelfuse_fuse_154_154t_154l_154tl_datasheet.pdf.pdf

simulate this circuit – Schematic created using CircuitLab


texts:
I am looking at a schematic for the Pixhawk 2 board. It has a complex power distribution system (see photo below)

Much of the complexity exists for one of two reasons

redundancy
shutting off external connections so an external short does not kill the system

The part that interests me is in the bottom right hand corner of the photo labeled "FMU LDO" (U5001 in the schematic). There are separate regulator outputs for the microcontroller (FMU) and the sensors. I am not clear why they split the supply here.

What value does that add? Would this circuit behave correctly on a single supply?


texts: ATmega328P: Reading from ADCL make ADC stop conversion

texts:
I am using a simple code to read from ADC pin A0. When I read from ADCH and ADCL. The result is correct only once in the startup. When I change the analog value in A0, output from the ADC don't change at all. Unless I have reset the mcu.
In the datasheet it is not state clearly that there is a register called ADC. They highlight ADCH and ADCL.
reading from register ADC work fine.
This is my simple code that don't work.
/*
 * Section: Function Defintion
 */
void ADC_Setup(){
    // Enable the ADC
    ADCSRA |= 1<<ADEN;
    // Select the refence voltage to be AVcc, which is connected to Vcc in the Arduino Nano board
    ADMUX |= 1<<REFS0;
    // Set Prescaler to 128, so that the ADC clock is 16M/128= 125Khz
    ADCSRA |= (1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0);
    ADCSRA |= (1<<ADSC) | (1<<ADATE) | (1<<ADIF) | (1<<ADIF);
    sei();

}
void ADC_StartConvert(){
    ADCSRA |= (1<<ADSC);
}
uint16_t ADC_read(){
    uint16_t i = ADCH*256 + ADCL;
    // if changed to i = ADC; it work fine!!
    return i;
}

What is could be the cause to make the ADC hold conversion because of reading from ADCL?


texts: Are there any real world examples of encoding data in EM polarization?

texts: Data can be encoded by modulating the frequency, amplitude and phase. But I can't find any references for encoding data in the polarization of EM waves (either analog or digital). This is probably for a good reason which I do not understand. Are there any examples of such schemes?


texts: Tolerance of SPI comms bit ratres (transmitter and clock master too fast)

texts:
I'm wondering people's thoughts on what happens when SPI timings between master and slave are "a bit" off. A bit being 2.34375 % too slow.

My setup is:

Slave device, which I cannot change, wants to be fed a clock of 128000.
My master device, which I can change, is currently stuck at 125000 due to the crystal that I have in it, 8 MHz.

I have ordered an 8.192 MHz crystal from RS with capacitors which will arrive in a few days. When that is running my master device, they will be in bitrate harmony.

In the meantime, when I read from the slave, it is returning data but it's a bit of a mess. I don't know if it's my bitrate mismatch or some other comms issue that I've not yet got under control.

What do you think?
* Never going to work until bps are matched?
* Should get some data coming in correctly but after N bits it'll start going wrong.

I know the latter can apply to UART but I'm unsure of SPI. Of course, in UART there is no shared clock, and in my setup, I'm providing a clock that is 2.34375 % too slow.

Thanks for your thoughts.

Rich

Added: the kit I'm talking to is circa 15 years old. It wont be some modern 32 bit ARM cored thing, it's a car CD player from the turn of the millenium.

Pictures that show 'good' and 'bad' behaviours:

This is the proper behaviour, between my CD player and geniune connected equipment:

This is with my incorrect clock rate:

This makes me wonder if the slave device is infact a real SPI device, or some microcontroller doing bit-banging out of time to me.


texts: What will happen to a transformer if rated output voltage is injected to the secondary terminal?

texts:
I believe that I have a three phase delta to single phase transformer 1Kva with input 415 v three phase and output 230 Vac single phase. ( Someone help me to identify what kind of transformer is this?)

I would like to test the transformer. What would happen if inject a 230 vac from a socket directly to the secondary of the transformer? Would I damage the transformer or it's perfectly fine and I would get the 415 v ac at the primary end. I'm just worried the sudden surge of voltage to the terminal may effect the transformer wingdings.

Below is the sample picture what I'm trying to do: (please ignore the immature wiring connection and the exposed fuse)

Some part of me saying this is a bad idea. What would happen and why is the question now?

Edit:
Primary connections:
Secondary Connection:


texts:
I am just starting with ARM and have made a small breakout board with an STM32F030 in TSSOP20 package.

I've uploaded the following program which works when the clockspeed of the device is set to 8MHz and also 24MHz:

#include "stm32f030xx.h"

void delay(unsigned int);

void delay(volatile unsigned int num) {
    volatile unsigned int index = 0;
    for(index = (num); index != 0; index--) {}
}

void initClock()
{
        RCC_CR &= ~BIT24;
        while( (RCC_CR & BIT25));   // wait for PLL ready to be cleared
        FLASH_ACR |= BIT0;
        FLASH_ACR &=~(BIT2 | BIT1);
        FLASH_ACR |= BIT4;

        RCC_CFGR &= ~(BIT21 | BIT20 | BIT19 | BIT18);
        RCC_CFGR |= (BIT18);        // set x3 multiplier (24mhz)

        RCC_CR |= BIT24;            // and turn the PLL back on again
        RCC_CFGR |= BIT1;           // set PLL as system clock source
}

void configPins() {
    RCC_AHBENR |= BIT17; // Power up PORTA
    GPIOA_MODER = BIT10; // make pin 5 (2x5=10) an output
}

int main() {
    initClock();
    configPins();
    while(1) {
        GPIOA_ODR |= BIT5; // pin 5 has an LED to ground via a resistor
        delay(24000*12);
        GPIOA_ODR &= ~BIT5;
        delay(240000*12);
    }
    return 0;
}

Now this simply pulses an LED attached to PA5.

When I increased the PLL from x3 to x5, by changing:

RCC_CFGR |= (BIT18);

to

RCC_CFGR |= (BIT18|BIT19);

instead of pulsing faster, the LED stayed on, although it is likely to be toggling on and off very fast rather than staying on. However, it should blink on and off like before, but just slightly faster (1.6x previous speed, by my calculations).

Is there some strange 'gotcha' that I haven't thought about? This is my first ever time using ARM chips so I'm struggling to figure it out. Thanks for any help.


texts:
What is the physical interpretation of dq0 axis transformation in electrical machines and power systems? How does this transformation helps?

Thanks


texts:
The input frequency is 2 MHz and the output should be 2 kHz since I used mode 3 and the initial count value N=1000d.
The output frequency is 500kHz.


texts: I have been studying electronics a bit at home in my spair time. I was wondering if manufacturers make schematics for PCBs? If I could get ahold of something like that i feel that I could understand the flow of the board better.


texts:
I am very new to circuitry and have attempted to make a circuit (only using IC's) which displays 0's and 1's from the shift register as LED's either on or off, and through the use of a 555 timer shift these values along every so often.

My circuit:

2 555 timers one with 10k resistors and the other with 20k, both with 100 micro farad capacitors. These timers are communicating with the shift register to make a series of moving LED's

Sorry if the diagram is a bit messy, this was very rushed. Basically I am using 2 555 timers on astable mode to tell the register to shift data or store new incoming data. One of the timers is running at double the entire cycle of the other (or at least it should be and I believe that is a possible issue), and thus when the timers match the shift register will shift in a 1 and when not a 0, this is then displayed via a series of LED's.

My issue:
The circuit is running some what fine until a few seconds in and then the register begins to shift in only 1's. I have no idea why this is occurring I have already disassembled and reassembled the circuit 3 times and I don't see a change.

Another but way less prominent issue which I thought I should mention, whenever I start the circuit I am given a random (it may not be) series of on and off values stored in the register.

Sorry if this seems a bit much, I am very new to circuitry and wanted to start moving away from using micro controllers for everything. This has become very tedious for me and just wanted an opinion or two.

Thanks.


texts: Altium Designer 17.1: importing or copying parameters for 1 project to another at once

texts:
Can you please tell me if there is a way to import/copy all parameters (Design>Document options-Parameters) (at once) from other project in which I have already added. Or is there a way to make my parameters as default so they already exist when I create a new project. So that they can be included in BOM.

There are about 30 parameters (company requirement). And I don't want to add 30 parameters manually each time I create project.

    There is one project complete with schematics and PCB layout in which these parameter exist and

    There is another project also complete with schematics and PCB layout in which I need to add these parameters

parameters in yellow circle are few which I want to add in my another project


texts: Do binary numbers move in sequence ones and zeros or parallel at once to ALU for addition?

texts: Do binary numbers move in sequence ones and zeros or parallel at once to ALU for addition, I mean ones and zeros in sequence vertically to ALU or parallel horizontally AT ONCE?


texts:
I’m new to EE and I have a project I’m working on that has confused me.  I have an old display from a laptop that I want to make into a custom 2nd monitor, I bought a driver board for that model display. It has hdmi for the input and a separate dc jack for the 12v 2A power input. I am wondering if there is a way to get a usb c cable and split the lines to the hdmi port and get a negotiation board to ask for the 12v from my laptop usb c port.  Would the protocols for hdmi and usb c line up if I require the data lines from the usb c cable and require the power lines to power the board.  I’m not afraid to learn what I need to learn. I would really love to use a single usb c for power/data transmission instead of two separate wires.  Any information greatly helps me. Here is a link to the board https://www.ebay.com/itm/LCD-LED-controller-board-kit-DIY-HDMI-VGA-DVI-for-LTN156AT34-LTN156AT36-1366X768-/153148696996
If I can’t split the lines, how hard would it be for me to make my own usb receiver/hdmi converter. I have basic programming skills and can learn anything I need to for this project. Thanks.


texts:
I want to discharge a lead acid battery of 12 V having a capacity of 100 Ah for 20 hours.

100 Ah divided by 20 hours = 5 A

12 V divided by 5 A = 2.4 ohms

Is my formula correct? Should I discharge with 2.4 ohms rheostat?


texts: Why don't my rechargeable AAA batteries work in my cordless phone?

texts:
I'm trying to replace the AAA batteries that came with my BT cordless phone, as they are terrible quality and have quickly degraded (they now only last about 20 minutes after full charge). They are 1.2V Ni-Mh, 550mAh, and similar to these.

I have some good Duracell AAA rechargeables, also 1.2V Ni-Mh, 750mAh. My question is, why don't these work as a replacement? Putting these into the phone does not give power to the phone, whereas swapping them out with the old batteries turns the phone on straight away.

As far as I can see there are no listed properties of the batteries that differ apart from the mAh, and I know enough about electronics to know that it shouldn't make a bit of difference to compatibility.

Is there some unlisted property of batteries that is causing this?


texts: How to wake STM32F103 by RTC using HAL libraries / Registers?

texts:
I've started digging into STM32F103 using HAL Libraries and raw registers. It's the first time to program at such low level.

Anyway following a video I've successfully implemented "Standby" mode.
https://www.youtube.com/watch?v=O82rj9qxkgs

I need an RTC to wake it up instead of a button. So I read the reference manual without really knowing how to start and finish it up.

Searching the internet, I found 2 main categories of sources: sources using Standard Peripheral Library (SPL), which is not my case. And sources using registers.

Anyway couldn't successfully implement the "RTC Wake Up" method.

I'm using this resource as my code starter.

Anyway, because I don't need RTC Calendar, I've removed any setting/reading date/time as I don't need them.

And I put a LED toggle to:

void HAL_RTC_AlarmAEventCallback(RTC_HandleTypeDef *hrtc) {
   HAL_GPIO_TogglePin(LED_GPIO_Port,LED_Pin);
}

What I observe now: the MCU toggles the LED At the start of sleeping (couldn't measure time), then continues sleeping without running main() again.

The MCU wakes up successfully using WAKEUP positive edge via a button.


texts: Why is superheterodyning better than direct conversion?

texts:
What is the advantage of having the extra stage of IF, extra local oscillator and extra filtering stage and amplification. It just seems like more work and circuitry. Surely the direct conversion to baseband and the intermediate conversion to baseband are both going to go through the same passband filter at the end of it that isolates the original frequency range?

I see answers such as 'it allows common circuitry to be used rather than separate circuitry for each frequency', basically:

  Without using an IF, all the complicated filters and detectors in a radio or television would have to be tuned in unison each time the frequency was changed, as was necessary in the early tuned radio frequency receivers

But I don't understand because they could all be tuned to the baseband signal for instance rather than the IF, eliminating the problem described.

I also see:

  So a narrower bandwidth and more selectivity can be achieved by converting the signal to a lower IF and performing the filtering at that frequency

But why not perform the filtering only at the baseband frequency IF=0. That is a lower IF, right. Does the addition of the IF passband stage improve the sharpness of final passband as opposed to doing it directly?

The only disadvantage I can understand is the leaking local oscillator and doesn't this happen more at higher frequencies? An IF could allow the first LO to oscillate much slower.


texts:
I want to use this chip (ST3232CDR) as an RS232 transceiver. The problem is that I want to power the chip using 2 levels of voltage (3.3V and 5.0V) using a simple jumper, but in the datasheet (http://www.st.com/content/ccc/resource/technical/document/datasheet/group1/40/2c/7f/62/3a/3f/47/3c/CD00002253/files/CD00002253.pdf/jcr:content/translations/en.CD00002253.pdf) page 7, the recommended capacitors values are different according to supply voltage level. How can I solve this problem. Is it okay to same capacitors for the two different voltage levels? or not?
PS: I am using this chip as an RS232 transceiver to interface an ATmega32 with db9 connector using UART.


texts: Is Bluetooth less susceptible to jamming than wifi?

texts: I am developing a mobile peer to peer application that will probably be subjected to RF jamming, and I'm wondering if bluetooth is perhaps less susceptible to jamming than ad-hoc wifi. Bluetooth has 79 channels and wifi has 14. Also looking for any general information on the efficacy of jamming (how much jamming at what range will destroy a connection, etc) against wireless networks.


texts:
I want to use the DMOS low-Dropout regulator REG102 3V3, but in the datahseet REG102 of the regulator i found two configuratons. The first configuration is without resistors divider and by connecting a capacitor on the output. The second configuration is with voltage divider,in this configuration the voltage Vout is depending on the values of the resistors and voltage Vref as is shown in the figure below:

My question is :
How the voltage Vin influence the voltage Vout in case of use of the voltage divider ?


texts: Boosting 18 V drill battery to 60 V to power LED lights, problems with voltage stability

texts:
I have a bunch of Dewalt 18 V batteries and 2 LED shop lights that I converted to DC, specifically 60 V, 1.5 amps per strip. I have had mixed luck and I am looking for a better approach.

I have no problem building boards, but I was trying to take a short cut and I grabbed one of these:  https://www.amazon.com/gp/product/B07L6F6S6S
to boost 18 V to 60 V. This did work, but as the batteries drain the voltage went down and the boost went down proportionally, so the light did not last a long time. I added a 15 V regulator, but that got super hot.

Does anyone have an opinion on what is the right way to do this? I need to make a constant voltage power supply that takes 12-18 V and boosts to 60 V, which does not fluctuate as the battery drains.


texts: Reading from Analog Magnetometer with Raspberry Pi

texts:
I'm trying to read an analog magnetometer using the Raspberry Pi Zero. I never worked with the Pi directly before; it was always through an Arduino hooked up to the Raspberry Pi. However, through research, I found that the Pi doesn't really play well with analog sensors, so I have to convert the analog signal to a digital one in order for the Pi to read it.

Aside from reading it out through an Arduino, Adafruit mentioned that you can wire your analog sensor to the MCP3008 to convert it to a digital input. A very rough schematic is shown below:

simulate this circuit – Schematic created using CircuitLab

My choice of magnetometer aside, what design considerations should I take into account when working with ADCs? Do I need to do anything to ensure that the clock and DIN/DOUT lines are stable? Is it advisable to have AGND and DGND be hooked up to the same GND plane with the Pi? This circuit feels a little too simplistic, so is there anything else that is required to make this work?

Just in case anyone asks, I'm using a magnetometer as part of a project to measure a 10 tesla field and record the data with a Raspberry Pi.


texts: Please see attached. I am unable to view the Poly, Metal, Cont layers for the PMOS & NMOS instances. Need a bit of assitance on how to fix this issue


texts: Will "dimmable" 120VAC LED bulbs work on half-wave-rectified power?

texts:
My stove's vent hood has a pair of 120VAC 50W MR16s with GU10 bases, e.g. these halogen bulbs. These are some of the last incandescent bulbs in my house, and I'd like to replace them with something that uses less power and lasts longer, e.g. these LED bulbs.

The curveball: the vent hood's light switch has three positions, "Off", "Bright" and "Dim". I'm 99% sure that the "Dim" position just puts a diode in series with the bulbs, so that you get half-wave rectified AC. The LED bulbs I'm interested in are "dimmable", but I'm sure the expected application is with the usual triac dimmer that gradually blocks parts of each half-pulse, rather than completely discarding half of the pulses. (BTW, we usually use the "Dim" setting, as it's plenty of light for us.)

How likely is it that a "dimmable" 120VAC LED bulb would function (hopefully at half brightness) when supplied with half-wave rectified power?


texts:
I need to send a command to multiple I2C devices on the same wire. The devices are OpenServos. Each device get's it command and begins processing the information in the command.

How do I ensure that they all start processing the command at the same time?

EDIT: Just to clarify, this question is mainly about I2C's ability to support syncing.


texts: Boost converter: Finding conducting period for diode in DCM (theoretically)?

texts:
I am having a problem finding the conducting period for the diode in a boost converter operated in DCM (theoretically). It is part of a multiple-choice assignment with three questions related to the boost converter operated in DCM:

a) Find the duty cycle

b) How long time is diode conducting?

c) How long time is the inductor without current?

Given parameters:

\$f_s=30kHz\$

\$P_{out}=P_{in}=5kW\$

\$V_{in}=325 V\$

\$V_{out}=1500 V\$

\$L=22\mu H\$

The converter is ideal (lossless). Capacitor and inductor are big enough so no ripple is conceived. I have deduced the following:

Deduced parameters:

\$T_s=33.3\mu s\$

\$t_{on}= 26.11 \mu s\$

\$t_{off}= 7.22 \mu s\$

\$D= 0.7833\$

\$ I_{in} = 15.38 A \$

\$ I_{out} = 3.33 A \$

And it is known that the slope of the inductor current is:

\$ \frac{dI_L}{dt} = \begin{cases}
\frac{V_{in}}{L},  & 0 < t < t_{on} \\
\frac{V_{in}-V_{out}}{L}, & t_{on}< t < T_s
\end{cases}\$

My approach:

I have tried to take the solve the equation for the inductor currents at each state:

\$ solve\left(\int_{0}^{D\cdot T_s}\frac{Vin}{L} dt = \int_{D\cdot T_s}^{t}\frac{Vin - Vout}{L} dt \right) = 18.88 \mu s\$

But it does not seem right (it is a multiple-choice test and I am worried that I have missed a key point).

Boost converter:

On state:

Off state:


texts:
I bought a replacement pellet stove auger motor rated at: 120V, 0.51 amp, 1 RPM.  (ASIN: B0032D26I6).  I installed it into the stove and it works, but the feed rate is too fast and my flame is too high.  I think I got the wrong part.  (This is actually a dangerous situation since the stove will overheat on high setting and shut down)
I've been researching the correct part and I found what I think to be the correct motor with a rating of: 120V 60Hz 0.72FLA 1RPM.  (Part #: EF-001.  ASIN: B0095LLIII - You can see the specs on the picture of the product).
I talked to someone who indicated to me that the amp rating would affect the rotation.  Is that true?  How does that work?  Would this second motor "slow down" my pellet feed rate?  If it is not the amps, then what would affect the feed rate?
EDIT:
I bought the second auger motor, EF-001, and installed it this morning.  Now the flame is the correct height (because of the correct pellet feed rate).  Why would 2 motors, both 1RPM feed at different rates?
Standard US 120V electrical service


texts:
This is an hypothetical question, not for the real build.

Let say there are 64 filament bulbs runs on AC 240V mounted in 8x8 matrix pattern. These lamps are to be controlled by only 16 switches (8 switches mounted in x direction and another 8 in y direction), where the coordinate intersections of these switches (total 64 points) represent the 64 lamps.

In this configurations, any two switches (one in x and another in y) will turn on only one lamp.

What is the best way of accomplishing this built with minimum components and  minimum wires.?


texts:
Im working from a reference design for an NXP home automation modem.

The capacitor with the green arrow is well described.

The capacitor with the red arrow is not. The schematic seems to suggest that the capacitor is polarized. I didn't think that a polarized could be used in such an application. (an offline dropping power supply)

What type of capacitor (aluminum, film, ceramic, etc...) would be suggested in this application?


texts: Why do some SMD electrolytic capacitors have platforms?

texts:
I’m working on a computer monitor’s power board (to replace a capacitor or two, which I assume is the problem), and found these:

Replacements are easy to find, so no issues there, but I’m curious why the SMD aluminum electrolytic capacitors are on little platforms (or spacers). To buffer swelling maybe?


texts: Digital Rotary Encoder -- Broken? Or am I misunderstanding how it works?

texts:
I apologize if this seems like a fundamental question, but I feel like I'm missing a fundamental understanding about digital rotary encoders, because none of my basic encoders are working as expected.

These are the encoders I'm working with. Link to Encoders

Based on my fundamental understanding of an encoder, it's basically like a double switch that are 1/4 cycle out of phase. At times, 1, 2, or 0 of the encoder pins will be connected to the base pin.

Given this, it seems like the resistance between pins should be either 0 or INF? Correct? Depending on the current position of the encoder?

If the multi-meter was showing 0 resistance (closed switch), and if I move the encoder two clicks, then it should show INF resistance from pin 1 and base, correct?

I'm losing my hair becuase I have several encoders all acting the same way....always showing INF resistance between pins ALL THE TIME.

Please show me what I'm doing wrong.

NOTE:   I'm currently hooked up the the pins on the side with 3 pins. Pin 1 and 3 are encoder pins and Pin 2 is the base pin.

--- EDIT:

I got a response from another forum that mentioned that in a single click the pins complete the entire cycle (A HIGH, B HIGH, A LOW, B LOW).  Is this true? Does anyone have a video or article that says this?


texts: Stability of BJT circuit using Re resistor

texts:
This is a post I found on Quora. I don't understand why decreasing Vbe decreases the current.
Vbe=Vb-Ve
To decrease Vbe you could increase Ve, Vb doesn't necessarily have to change, so neither Ib....


texts:
something has been bothering me for awhile. When I look at a circuit involving anything more complicated than RLC components (and perhaps op-amps) I struggle to figure out what it's doing unless its a configuration I've seen before.

In contrast, I feel pretty confident that no matter how complex an RLC circuit I'm given I could eventually figure it out.

Now when I'm analyzing an RLC circuit my tools are basically

\$V = IR\$
\$I = C \frac{dv}{dt}\$
\$V = L\frac{di}{dt}\$
Parallel and Series combinations of those components (I guess this isn't really separate from Kirchoff's laws but...)
Kirchoff's Laws

So what I'm asking is what tools am I lacking for analyzing more complex circuits? Mainly I want to know how to analyze circuits involving BJTs and FETs. It seems like there are so many modes of operation for transistors its hard to keep them all straight. Anybody know a good website that lays out everything?

Thanks

EDIT I also want to mention that in practice there are things like \$V \neq IR\$ when temperature changes. I don't care about that for now, I agree with stevenvh that simulation is needed, but I want to be able to have the concepts down well enough to design a circuit which I can then tweak with a simulation etc.


texts: AC (230V, 50Hz) line detection using H11aa1

texts:
I am new to Power Electronics, I am working on to AC line detection using H11AA1 IC. Schematic is as shown here.
With the following calculation, I figured out the resistor value R1=8K
 R1= ( Vs - V_led)/(10mA) which is in my case  R1=( 230 - 1.5)/(10mA) =22.8K;
So I added R1 20 K/1Watt but I could not achieve the result;
Has anyone work with H11AA1 IC for the similar purpose, Do I need to change R1 value??
DataSheet of H11AA1 here vishay.com/docs/83608/h11aa1.pdf


texts: Experimental efficiency curve of a buck converter

texts:
I made a buck converter, And I tested the circuit under following conditions:

Vi = 32V
R = 6.8 ohm
Fs = 125kHz

I got this result:

I think it's kinda odd that the difference between the theoric output voltage and the experimental one get smaller when the duty cycle increases.

The bigger difference between experimental and theoric voltage happens when the duty cycle is close to 0.5, I think two factors may explain this result:

1)  The current ripple has its peak just at a duty cycle of 0.5, bigger currents imply a bigger lost since the Ron of the MOSFET.

2) The second one will be that for a duty cycle under 0.5 most of the time the diode is ON, for a duty cycle bigger than 0.5 the transistor is ON most of the time. Since the power loss in a diode is bigger in the diode this may explain the improvement in the efficiency for a bigger duty cycle


texts:
I was going over a request for a solar battery charger, and one of the points was a Low Voltage alarm (possibly meaning a LVD) to be triggered at -48VDC.
This is a bit confusing as, to the best of my knowledge, most battery chargers and banks are rated at positive voltage such as +48VDC.

I know that +/- is mostly a matter of where you consider the ground to be, so does this mean that their battery bank is grounded at the positive pole? Or what is the usual way of connecting a battery bank of 48V to equipment that is working with -48V?

I am trying to figure out why they require a negative voltage for the LVD, basically.


texts: Interfacing a 16x2 Character LCD to the Arduino

texts:
A friend recently gave me a set of three (old) 16x2 LCD displays.  (datasheet)

However, I'm having difficulty thinking through how to connect one to my Arduino.  Particularly, each LCD has 14 (!) pins, of which 7 are denoted "data bus line" on the datasheet.

In the past, I've connected my Arduino to a LCD screen using serial connection, and I have an I2C LCD that I won at a competition recently (I've yet to use that one, though--I'm waiting on a specific type of jumper cable).

However, I've never used an LCD with this many pins, and certainly don't want to hog all the pins on my Arduino (Uno).  So, my question is:

  How do I communicate with this LCD, using my Arduino? (While keeping in mind that I want to do other things with the pins.)


texts: Is it possible to increase the current avalible without changing voltage on my DAC circuit?

texts: I am using a Raspberry Pi and a Adafruit MCP4725 to control a mass flow controller, as well as powering the DAC, and I am meeting the bare minimum of current to control it with the Adafruit MCP4725. The voltage range is fine. Is there a way to up the current available, even just a little?


texts: How do I find capacitors for low dielectric absorption?

texts:
I'm looking through digikey's option on polypropylene capacitors.

None of them seem to specify dielectric absorption.

This is for a low voltage sample-hold circuit. Low leakage is good, but low dielectric absorption is more important.  I cannot seem to figure out the difference between PP, Metalized PP, and Stacked PP capacitors.

I'm seeking advice for specific capacitors or a way to decipher the datasheet.  For instance, does the voltage rating tend to matter? Does lower leakage/higher insulation resistance tend to mean a better dielectric absorption specification?

Thank you


texts:
I would like to build an isolated DC to DC converter for low current.
I have found this nice chip, but in the datasheet there are two inductances listed but not in uH or mH. It's is only in Ohms. Can you help me please?
Datasheet: https://www.mouser.de/datasheet/2/609/adum5028-1378717.pdf


texts: How is the current limited in this common drain circuit?

texts:
I'm trying to create a dummy load circuit, but it was limiting itself around 1.7A, so I built this circuit. V1 is 0 - 5V via a potentiometer, and V2 is a 5V / 3A power supply.

simulate this circuit – Schematic created using CircuitLab

When I increase the voltage Vgs, even up to 5V, the current through the power supply (measured with a multimeter) limits itself to around 1.7A. If I remove the 1 Ohm resistor, the current is not limited at all, and keeps rising.

I have looked at these two diagrams on the datasheet of the mosfet, but can't seem to figure out why the current limits itself due to the resistor:

I wanted a 3A current through the power supply / mosfet / resistor, so I looked at figure 3. For a 3A current, Vgs needs to be ~ 3.4V. At 3A, there will be a 3V drop across R1, so Vds will be 2V. Then I looked at Fig 1, and at Vds = 2V, it should be able to have an Id of 3A, given that Vgs = 3.4V.

So why can't  I get 3A out of this circuit?


texts: Is it OK to rely on an ADC's internal protection diodes?

texts:
Related to: ESD protection of ADC input.

To protect an ADC input from out-of-spec voltages, including ESD, it is often recommended to use diodes connected to GND and Vcc. If I have a 1k series resistor on the ADC (ADS1158) input, is it OK to rely on the ADC's internal diodes, or is it worth adding the diodes as discrete components.


texts: designing a sequential circuit by having it's value table?

texts:
when learning about combinational circuits we could draw the truth table and construct a circuit by the help of min/MAX terms  .  and we could further simplify it with Karnaugh maps .

BUT how we do this in a combinational circuit .

lets say i have a table like below .

now how can i make a circuit out of this table

the problem is both in a K-map and truth table the only meaning full states for a bit (like the clock in here) are 0 and 1.

SO we cannot Do any thing about the rising or falling edges .

PS.( this example is a D flip flop that is transparent both in rising and falling edges )
BUT i want a method (algorithm) like the Min/Max term (or Karnaugh maps) to solve ANY question not just this one !


texts: What does the line and load mean in this question?

texts:
Here is the question

I don't need the answer, I just want to know what the line and load really represent here


texts: Chain 16-channel analog multiplexer/demultiplexer

texts:
I'm trying to figure out how to chain six 74HC4067 or similar 16bit multiplexers.

My goal is to read multiple analog inputs one after another with Arduino.

I have only 1 analog pin input and 7 digital pin output, which is enough to address each input (2^7 = 128 > 6x16 = 96). So I need to figure out how to select each.

Simplest solution wins, please avoid using any shields or shift registers, keep it simple.


texts: Hi, I would like to know the best way of turning on an LED for each switch that is opened. The switches are normally closed. The load is a motor. When any switch opens the motor turns off. But it is not always easy to see which switch it is. A nice LED display would work good.


texts: Base current in a npn transistor in view of its small signal model

texts:
We know that in a forward biased transistor we have βIb = Ic.
However in the model it's clear that the above equality doesn't hold, we now have Ic > β.Ib.
What's wrong in my understanding of the model.
Any help is appreciated
Thank you.


texts: Does dual-bank read-while-write work properly in STM32L071?

texts:
I'm trying to reprogram the NVM (flash bank 2) while running code from flash bank 1 in the STM32L071CB microcontroller.

As AN4808 and AN4767 states, "the memory interface is capable of reading both banks in parallel, or reading one bank while writing to the other...", but I'm experiencing some problems:

Debugging shows that FWWERR bit goes high in the flash status register during flash bank 2 half-page write operation. It means that writing flash bank 2 has been stopped because of code fetching.
Erasing bank 2 by code in bank 1 works properly.
Writing by words bank 2 by code in bank 1 seems to work properly (but I'm having doubts if it's only a coincidence).
Half-page writing ends with FWWERR bit set in FLASH_SR and zeros in the memory I'm trying to write.

I know I'm missing something, but I can't find out what it is. Maybe someone had similar problem? I'm starting to think that there's something wrong with the microcontroller (errata sheet points out some problems with dual-bank switching mechanism, but it shouldn't be a problem in my case, because I'm not switching banks right now).

My function works properly when executed from RAM memory, but I'd rather want it to run from flash bank 1.

The function (1) below is responsible of writing half-pages. Code (2) shows the way that I'm calling (2).

(1)

void nvm_prog_write_halfpages(uint32_t* addr, uint32_t* data, uint32_t length){

    // There can't be any previous alignment errors in the flash SR
    if ((FLASH->SR & FLASH_SR_PGAERR_Msk) == FLASH_SR_PGAERR){
         FLASH->SR = FLASH_SR_PGAERR; // clear any previous alignment errors
    }

    // Check if any operation was stopped previously due to code fetching
    if ((FLASH->SR & FLASH_SR_FWWERR_Msk) == FLASH_SR_FWWERR){
        FLASH->SR = FLASH_SR_FWWERR; // clear any previous fetch related errors
    }

    nvm_prog_unlock();

    FLASH->PECR |= FLASH_PECR_PROG | FLASH_PECR_FPRG;

    uint32_t cnt = 0;
    while (length > 0){
        *addr = *data; // Destination address will be increased by the hardware automatically
        data++;
        cnt++;

        // When a half-page has been written
        if (cnt == 16){
            while ((FLASH->SR & FLASH_SR_BSY_Msk) == FLASH_SR_BSY)
                ;
            cnt = 0;
            addr += 16; // Write the next half-page
            length--;
        }
    }

    FLASH->PECR &= ~(FLASH_PECR_PROG | FLASH_PECR_FPRG);

    nvm_prog_lock();
}

(2)

nvm_prog_erase_page((uint32_t *) 0x08010000); // Erase flash bank 2; it starts at 0x08010000

uint32_t dummydata[32], i;
for (i=0; i<32; i++){
    dummydata[i] = i;
}

nvm_prog_write_halfpages((uint32_t *) 0x08010000, &dummydata[0], 2); // Write 2 half-pages at the beginning of flash bank 2