texts: Best way to electrically and thermally connect a FET to an Aluminum heatsink

texts:
I am designing a drive and need to electrically and thermally connect the tab of a series of FETs to an aluminum internal heat sink that is also used as an electrical bus.

It seems the best way to go would be to solder the FET tab to an intermediary copper layer and the copper layer to the aluminum.

Is there some sort of special flux and/or solder paste that would be needed to perform this? Methods to deal with oxidations? Would a reflow oven of some sort be required to ensure the copper/aluminum are soldered properly?

Are there processes out there to do this sort of thing?

I have struggled to find much information on this.

Thank you for your time.

Related question that came up from comments/answers:
Does bolting to aluminum for electrical contact have any oxidation concerns?


texts: Equivalent Circuit for the RLC circuit to find the transfer function

texts:
I have a series RLC circuit with mutual inductance between the transmitter end and the receiver end.

The circuit is

I am trying to formulate a simple transfer function. I can formulate the transfer function by applying KVL to both transmitter loop and receiver loop and solving them to derive, load voltage/input voltage.

But I am a beginner in circuit theory and till now I have never come across finding the transfer function of a circuit with mutual inductance.

So if somebody can guide me in solving it. or if you know any example then please let me know.

Thanks in advance.


texts:
I want to design a transformer (100VA 230V/12V) with E-I core. The following scheme illustrates the dimensions of the core that I know. How can I determine the depth of the transformer?

I know that in the most applications the depth of the transformer is B/2. Is there a better way to calculate the depth?


texts: CD4015BC static shift register: technical specs question

texts:
Currently looking into the specifications of the CD4015BC static shift register, I came across a couple of specs for which I have some questions:

1) The clock rise and fall times should be below 15 us, what happens with clock pulses that have longer rise times? Does the registers shift well? Or does it's behavior becomes unreliable?

2) There is a spec about minimum data set-up time (30us max for VDD=15V), what is meant with this spec please?

3) I don't find anything about the maximum output current on the output pins. What is mentioned is: "High level output current: Typical -8.8mA, minimal -3.0 mA" without specifying any load resistance...

Thanks for helping out with these.

(I am currently looking into a design which uses this kind of register in a cyclic way: at startup it clocks in a couple of random bits and then the output of the last register is fed back into the first input. Works well, the bits that were clocked in are cycling through the registers. But when changing the clock source from time to time, the bits that were clocked in originally, are gradually disappearing, all bits become zero... I suspect slow rise time of input clock to be the cause..)


texts: When I added a resistor to a set of christmas lights where I cut off bulbs, it gets hot. Why does a shorter string of lights not need a resistor?

texts:
So I have learned that in order to shorten christmas lights, you need a resistor. And unless you get a very very big resistor (which is expensive and hard to find, or use a heatsink, or string many together to up the wattage a lot), it will get very hot and you can't let it touch anything.

I don't know what I am missing why I needed a resistor for shortening a christmas string unlike the shorter string. For example, someone could manufacture a string with 78 bulbs instead of 100, and I am sure they would not have a hot resistor on there.

But why does a shorter string of lights not need a resistor?

I'm not sure why I am needing to add a hot resistor, I wondered what they do in the manufacturing process to determine how to make the string without a resistor? Is it the type of bulb? Or is there something else involved?

Is there a way to emulate the shorter string of lights without the resistor?

Note: these are strings which plug into a wall outlet of 120V. The voltage therefore cannot be adjusted since the power outlet cannot be adjusted.


texts: What on the arduino is generating the following signal?

texts:
I was playing around with looping a scope probe and placing that loop over various parts of different circuits. I tested a few different boards, but the arduino mega came out strongest, with quite a clear 32MHz signal being coupled into the loop. What is this signal, and where is it coming from?

Notes:

The image of the loop over the arduino is where I could get the strongest signal.
Pressing 'reset' on the arduino would stop the signal.
The arduino was running the "ArduinoISP" sketch.
The scope is acquiring on average mode with 256 averages.


texts: stm32cubeMX difference between Gpio_output and Gpio_input

texts: I will use L476RG to connect with a battery power board, battery board will use two Gpio ports to ONLY send out info, such as battery is full, battery is in charge, and so on, now the question is, in STM32CubeMX, shall I set those two Gpio ports as input or output status? Also in Hal function HAL_GPIO_ReadPin(..), what is value I could get? in battery manual I should read blinking 2.5Hz and 0.5 Hz, high and low 4 status. Thanks


texts: I have a USB to Serial breakout which has CP2102 and MAX232 chips on it. I wrote a program in Keil and generated the Hex File. How do I flash this hex file onto the AT89C51 (which is also another board with all the capacitors,resistors and crystal oscillator, everything is there) using the USB to Serial breakout? Flash Magic works only for philips chips, what is the alternative to ATmel chips?


texts:
I want to charge mobiles using a solar panel.
Most phones would charge well with 5V 1A/1.5A.
My panel specifications are as follows-

Key points:

Maximum power 10Wp (peak wattage)
Voltage at maximum power 18V
Current at maximum power 0.56A
Open circuit voltage 22V
Short circuit voltage 0.59A

I have used a circuit that I have designed with an LM2596-5V IC t(I haven't used the module yet) to bring down 18V to 5V and at least 1A current in output (ie 5W.)
This is the circuit I have used:

In reality I am getting 5V 400mA in output (ie. 2W only.)
I have used electrolytic capacitors above.
Can someone explain what's wrong here?
Buck converters are supposed to give 80% efficiency, here I am not even getting 30%.


texts: Advantages of using a current loop in driving a BLDC motor

texts:
I've been reading the answers to the question:

How to realize constant acceleration control for BLDC motor?

However, it is not specified what are the advantages of adding a current control loop to drive the motor. Why not just drive the motor PWM from the output of the velocity loop PI controller?


texts: How to disable/overwrite tStop overlap/conflicts detection in eagle's DRC?

texts:
please refer to the image below for the overall idea:

In eagle, there is a layer called "tStop" and with its counterpart for bottom layer being "bStop". As I manage to gather, it's some sort of mask that stops the green insulation so it won't cover up your pads, vias etc.

Now as you can see in the picture, two tStop masks overlapped, which logically speaking shouldn't be a problem since it means during board fabrication, this area will not be covered by insulation, the overlap at worst and at best, serves as some sort of double guarantee.

But the problem is that eagle list this as an error, which doesn't really impact my board in any significantly negative way. And I now have close to a thousand of errors mixed with actual problematic ones, which makes it quite difficult to ignore/approve by hand, so, what I am asking is, can I disable/overwrite it? Hide these error of the same nature at least, while leaving the rest shown?

The errors look like this with no details listed and no hint to work with:


texts:
Supply Voltage +-15 V to +-24 V
Goal:To have an adjustable single low voltage output (-0.5 V to 0.5 V ) from dual supply voltage.

What I want to do is to have dual voltage output which will be connected to potentiometer for having small voltage output (output 0 - 0.4 V)

I have designed with LM317 and LM337, but I want to try with LM7805 and 7905. Simply I will have 5V output for 7805 and -5V output for 7905. However the output current is low. Therefore I should somehow increase the output currents. I've seen somewhere that it can be done with external transistor but I did not understand exactly how. Could you please give me any ideas?


texts: Can I run this motor off of this solar panel?

texts:
I am trying to build a solar powered boat, and I have decided upon this 5V, 500mA panel. I can buy 3 or 4 of them to get up to the necessary voltage and amperage. The problem I have is that I can't find any good 5V motors; the closest are 6V, however as far as I know you have to match the same voltage exactly. I'm looking for the highest possible RPM and I want to spend less than $10.

Can I power a 6V motor like this one off of a 5V panel? What if I linked four panels to get 10V, 1A and used this motor, which supports 9V at 1.1A under load?


texts: SG3525 Closed Loop Inverter Waveform Problem

texts:
I'm using a sg3525 ic on a full bridge dc-dc converter in closed loop. The system is working fine, I don't have a problem with it. Output is just like what I want.

The problem is inverter part's output waveform is confusing my mind. When I use ic on open loop, the inverter has a normal output waveform(square wave), but when I switched to closed loop system is working fine but inverter output becomes weird.

I just want to ask that: Is this inverter output waveform normal at closed loop configuration? Because system is woking fine at closed loop but this waveform is confusing my mind because efficiency problems can occour.

Here is the waveforms:

Open Loop Inverter Waveform:(non-problem, normal)

Closed Loop Inverter Waveform:

Thanks for your help...

(It's a 48V to 360V full bridge dc-dc converter with 30kHz operating frequency at inverter part.)


texts: Systemverilog - Register Chain Simulation Problem

texts:
I wrote a Systemverilog code that gets an input and connects it to a chain of registers (I.E: a "word shift register").
The output is an array whose size equals to the number of registers + 1.
The output's zero index is simply a wire that's driven by the input.
This is my code:
module register_chain
#(
    parameter NUMBER_REGISTERS = 31 ,
    parameter WIDTH_REGISTER = 12
)
(
    input INPUT_CLOCK ,
    input [ WIDTH_REGISTER - 1 : 0 ] INPUT_DATA ,
    input INPUT_ENABLE ,
    input INPUT_RESET ,

    output logic [ 0 : NUMBER_REGISTERS ] [ WIDTH_REGISTER - 1 : 0 ] OUTPUT_DATA
) ;

logic [ 0 : NUMBER_REGISTERS - 1 ] [ WIDTH_REGISTER - 1 : 0 ] array_registers_data ;

    assign OUTPUT_DATA = { INPUT_DATA , array_registers_data } ;

    always_ff @ ( posedge INPUT_CLOCK )
    begin : registering
        if ( INPUT_RESET == 1'b1 ) begin
            array_registers_data <= '{ default : '0 } ;
        end else if ( INPUT_ENABLE == 1'b1 ) begin
            array_registers_data <= { INPUT_DATA , array_registers_data [ 0 : NUMBER_REGISTERS - 2 ] } ;
        end
    end : registering

endmodule

I'm seeing very strange behavior in my simulator:
OUTPUT_DATA [ 0 ] is the same as the input INPUT_DATA ( as it should ).
OUTPUT_DATA  1  is ALSO the same as the input INPUT_DATA ( which is a bug ).
OUPPUT_DATA [ 2 ... n ] get the delayed copies of INPUT_DATA as they should.
Do you see something wrong in my code ?


texts:
You are given a free running clock with a duty cycle of 50% and a digital waveform f which changes only at the negative edge of the clock. Which one of the following circuits (using clocked D flip-flops) will delay the phase of f by 180°?
A

B

C

D

My Doubt: I'm CS student, I'm getting confused with this type of question in which frequency, phase is asked. I know about basic flip flop and counter very clearly but how to approach such type of questions please help.


texts: Any issues with changing to lead-free solder?

texts:
I'm thinking of changing to lead-free solder. I've heard some people prefer a traditional Pb/Sn solder, but haven't heard any specific reasons why.

I'm mostly doing through-hole work, and I have a decent temperature-controlled iron.

So, are there any issues I might encounter with changing over? And are there any situations where I'd want to use a particular type?


texts:
What's the simplest circuit for an inline latching power switch?

I have a 12V lipo going into a step-down converter powering an Arduino. I'd like the Arduino to be able to completely power itself off (not simply go to sleep). However, neither the 12V lipo nor the converter have any built-in means of being controllable from a digital pin.

I've found several examples of latching power switches, but they're all relatively complicated, and assume the switch is incorporated into the regulator. I don't want to modify any components. I just want to put a "box" in between the 12V lipo and converter, wired to an Arduino pin, which will break the high-side when the pin goes low.

What's the simplest way to do this with the minimum of components?


texts: What is the synthesizable VHDL method for loop or memory module?

texts: I have an image processing application, first step is to do a thresholding operation (binarization). I don't know really if it better to use for loop (2-dimensional array) or to use a memory.  If I use the memory how can I access for every element (the size of the image is 640*480) using VHDL description?


texts:
Check schematic below, On power on, I want to create a delay when the relay turns on of about 20 seconds. Once its on, it stays on until the power is cut. Timing accuracy is not important. Now I could use a 555 timer, but then I would need a transistor as well. That's two extra components. So I thought of just using a simple RC circuit in parallel with the relay as shown below.

About the flywheel diode (D1), I think it wont be needed since the capacitor will supply the di/dt at power turn off ?

I also added diode D2 to discharge the capacitor faster at turn off


texts: Stabilizing IR Emitter/Receiver circuits

texts:
Need some help making these IR Emitter/Receiver circuits, and their power, more stable.

Building a large, 8’ x 10’ LED art installation (in progress details included). LED Butterflies in a grove of trees that interact with the viewer. Built in to the installations “tree” structure will be a field of IR Emitter signals with individual IR Receivers (built as “Butterflys”) triggering a group of LEDs on/off as viewer walks into and out of the area.

The conception is a large array of IR emitter signals - emitting at 38Khz for a distance of approx one meter - and a similar large number of “Butterflys”, each with its own receiver-transistor-LED load turned on by the reception of a signal bouncing off a viewer nearby (otherwise off).

Works in the test circuit but it does so only for a moment. The amps fluctuate from the emitter’s bench power source, starting at 20 mA increasing to 40 and higher. Once the amperage goes hi from the emitter, the LEDs on the receiver turn off. That’s bad. They need to stay on for as long as a signal is being received. Not sure how to stabilize that 38Khz signal from the emitter LED. Circuits are the simple and common ones found everywhere and the astable 555 timer/ IR Emitter values are derived from an online calculator. I understand that the wiring in the test circuit is very messy and that contributes to the instability BUT should these circuits work as proposed if all components are neatly on a small PCB? The emitter PCB would be shaped like a "leaf" and the separate receivers PCB would be shaped like the butterfly's body. Would there be any suggested changes I should make/adjust with power and or resistance BEFORE I send the schematics to a PCB shop?

Probably should go without saying, but I’m an artist not an engineer. Need help keeping these circuits solid, simple, small and powered for the interaction/art to show through. Side note: I’ve been looking for EE consultation, am willing to pay reasonably for time/expertise, but since this isn’t a commercial application, I can’t find anyone willing (consult suggestions welcome:) Please help.


texts:
I've been attempting to build my first lab power supply, I have my components, and have studied many circuit diagrams. I thought my knowledge was good enough, however I'm now at an impass. I have a 24-0-24 30w transformer. Now I get the following readings when measuring from the shown points;

When I measure between the two 24v outputs I get  the following;

FYI my end goal is to produce a 0-35V DC power supply unit using lM317T.

Now I want to use a four diode (namley 1n4001) bridge to rectify the output to DC, something like this;

Ok thanks for the super quick reply, so the revised circuit design is the following:

Now here I get the following readings which are confusing to me;

Here is the overall circuit

I'm sorry if I come across as stupid but, I just don't quite seam to understand the readings I am getting.


texts: Simulation result of bjt cascode amplifier

texts:
I use square wave as the input source to my BJT cascode amplifier. However, I got my output voltage as

I used transient analysis in PSPICE to obtain the simulation result. Can someone tell me whether the result is correct or the output voltage should be a square wave as well? I think this graph due to capacitor but I am not so sure about it.


texts: Current Source Circuit Internal Impedance

texts:
So I've been learning about current source circuits - this one in particular. I'm told that an ideal current source should give out the current no matter what happens to the load. But it should also have a ideally infinite internal impedance.

Rb, the 2 diodes and Re ensure that the current Ic remain constant - but I'm not sure how to prove that this circuit satisfies the high internal impedance requirement.

Any guidance?


texts: Not understanding why in overcurrent protection only a certain section will isolate (why not the whole system)

texts:
I'm having an issue understanding a simple concept for faults. I understand the principles of how the relays cause the circuit breaker to open etc when a larger current goes through them to provide overcurrent protection.

But I don't quite understand why only the breakers of a certain section of a circuit will trip in some cases.

For example for the following Circuit:

If a fault occurs at the highlighted section, why don't all circuit breakers open to isolate the fault. Doesn't this fault cause a much larger current to be drawn from the generator (e.g 10x the rated current?) and so wouldn't the other breakers trip as well not just the section where the fault is located. Also how does the generator supply enough current for this fault in the first place?

Essentially I'm having trouble understanding why only this section is isolated.

Thanks In advance


texts:
I bought an MSP430 to learn more about microcontrollers. My ultimate goal is to build a graphing calculator. I have read a few other posts about this but I still have some questions about the specifics. My plan now is to learn as much as I can about circuits with the MSP430 and move on to another type of processor when I am ready. I have been programming a long time (graphing calculators too) so my concern is just setting up the hardware. Right now my plan is to eventually make a simple version of the calculator and then make a more sophisticated version once I have some experience.

What processor would you recommend? I know this question gets asked too much. I am asking because I would like the final calculator to have a lot of RAM and Flash. How much memory would I have to work with if I used a really good ARM processor? If that isn't enough, how difficult is it to hook up RAM and Flash chips to your MCU?
This question depends on question 1 but from a design standpoint, isn't Flash a lot slower than RAM? In the calculators I have worked with, a lot of the routines the OS uses are executed from Flash. Couldn't you speed things up by storing the OS in the Flash then copying it to RAM the first time the calculator starts? Then when the calculator is shut off, a backup battery would keep the contents of the RAM loaded.
From a hardware standpoint, would it be terribly difficult to use two processors? I know getting them to cooperate and do anything useful would be non-trivial but it is interesting idea to give the second processor a task, like sorting a list with thousands of elements, while the first processor carries on with some other task. Of course this is overkill for a graphing calculator but it is an interesting idea for a hobby project.


texts: Noise problem with Arduino + relay + motor unit

texts:
I use an Arduino + relay + motor unit, got electronic interference and the unit lost control. I search out that I need separate power supply for Arduino and load.
My question is if they still use common ground, can the common ground separate the noise?


texts: Limiting Output Voltage of the Opamp-to avoid saturation

texts:
Problem:

my photo diode recieves pulses of width 10ns-150ns and repeating at rate of 1Hz-50KHz

the current from photo diode depending on incident light can go from 10nA-100mA,

in a nutshell, my application tries to digitalize the analog pulses for pulse width measurement

so i have 'only' two photo diodes to cover the dynamic range,after breaking the dynamic range in to multiple channles like 1uA-5mA(less than 1uA its hard for me to measure 10ns pulses for several reasons,find here, here) and 500uA-100mA, there are some special reasons like optical attenuation before one sensor which made to break the photo diode ranges in to overlapping one.

so for my first channel 1uA-1mA which is where i want to do I-V conversion using a TIA rather than using a resistor,so for a gain of 1K i was able to achieve proper gain 60dB at 100MHz, so i will not change the gain now,

through this 1uA will be 1mV and 5mA will be 5V, now that is not enough i have to put one more gain stage of 20V/V to read my 1mV, so the second stage would saturate with a input of 500uA itself, which is a set back to my approach
(to stick to the problem i did not post second stage)

Approach 1:

so i used this techinique of using diodes in my loop so that the ouput would be limited to the cutoff of the diode, but this is leading to oscillations in other words unstability of the opamp

Results:

for a current above 450uA the opamp starts slightly oscillating, for a given current of 1mA on the right you can see completely unstable, i thought the problem is due to switching time of diode being 5ns only, so i changed it to schottky which resulted full fledged unstability, so there must some problem with opamp or the setup, please guide

Approach 2:

limiting the output current of the photo diode itself to 500uA ? using a current limiter, which did not workout properly, because the approach itself affects the frequency response and also adds distortion to the signal, the question quoted tries to limit the current to 5mA it can also be applied for 500uA, find it here, as its failed i dont want to bring it here.

Kindly suggest me an alternate approach to tackle this, or any modifications to existing design to get rid of the problem, to put it short i want to cover the range of 1uA-5mA


texts: How bad is this soldering station from ESD perspective?

texts:
I found this cheap soldering station called OLED T12, which might be good for my current purposes (I'd like to solder cheap SMDs). According to the images 4 wires run from the station to the iron and the green wire is the ground. So I guess the tip is grounded on this station, which might be a slight ESD protection compared to for example the TS100, which - as far as I can tell - is not grounded. I found a similar Aiyima T12 station, which is AC, but looks almost the same as the first I mentioned and has 5 wires. I checked a few Solomon products too. The ESD safe irons and stations (triple the price compared to OLED T12) are always black and have 5 wires, while the non ESD safe products have only 4 wires and they are not black.

I'd like to know why the Solomon can solve this only with 5 wires, while the OLED T12 has only 4 wires and the tip appears to be grounded on it? I am pretty sure the OLED T12 is inferior to any ESD safe station, but I'd like to know whether it is any better than the TS100 from ESD perspective because of the grounding?


texts: Does the output of JK Flip Flop toggle continously?

texts:
As given in most of the texts and online resources, the JK flip-flop requires a clock signal with an edge detector circuit so that the flip flop will be sensitive to the inputs only when the clock signal undergoes transition from low to high(Positive edge triggering)

What would happen if the clock signal is directly applied to the JK flip flop? I'm not sure (correct me) if directly applying clock pulse to JK is called level triggering. The question arises when both J and K inputs are 1. Would it keep toggling at every high level(And output would be similar to flashing an LED from 555)?

We've performed the experiments of verifying function tables for all the latches and flip-flops in our practical sessions. But we have directly fed the clock output from 555 to the flip flops.

Does the type of triggering has no effect on functioning of a Flip-Flop?


texts: Does VSS (Logic Supply Voltage) on a L293D need to be connected for the IC to work?

texts:
Here is my breadboard using an L293D . Pin 16 (VSS) is at the top right.  I'm trying to have my project operate in sleep mode drawing as little current as possible.  When I added the IC, my draw increased about 24mA.  I was experimenting and pulled pin 16 which was connected to 5V and the draw immediately dropped to .54mA which is what I expected.

However the weird thing is that the IC still works.  Pin 8 (VS) is connected to 12V which will power my motors.

Why is this circuit working?

Edit: It looks like 12V is connected to Row 57, but it is just hanging loose.


texts: Ensuring common ground in a circuit with several voltage requirements

texts:
I'm working on a project that has components requiring various voltages.

3.3v --- to power a set of laser diodes (qty 24 @ 50mA = 1.2A)

5v --- to power a set of infrared transceiver sensors (qty 24 @ currently unknown current)

9v --- to power an Arduino board and some peripherals (some typical Arduino-esque current draw)

I've never done a project like this (with various voltage requirements), and I'm wondering what the best practices are for powering these separate sub-systems.

Would one of the following scenarios be most appropriate?

Scenario A - Multiple power supplies
--- Use a separate AC/DC power supply for each required voltage (Meanwell or somesuch)
--- Somehow connect all the grounds together

Scenario B - One power supply and voltage regulators
--- Use one AC/DC power supply rated at 9v
--- Step down the voltage to 5v and 3.3v using appropriately rated voltage regulators

Scenario C - Something I could never have imagined!

Thanks in advance.


texts:
After getting two modems (dev boards) Siemens TC35 and SIM900A I cannot get them to send SMS.
From the research it seems that somehow SIM cards will not register to network.
I bought three SIM cards from different networks currently operating in my location.

Commands to GSM module:

AT
OK
AT+CREG?
+CREG: 1,0
OK

Any hints?

EDIT:

All SIM cards have their pin security check disabled.
All cards have been inserted into phone, tested for a call and tested to send SMS to another phone. Also all of them all full of credit.

EDIT2:

Just tested cards with GM862 module with same commands and all works fine (sending SMS works withut any issue)

EDIT3:

For reason unknown to man kind, and all the frustration I've decided to run TC35 without SIM card, and add SIM card in the process of running.Running AT+CFUN=1 , and then trying to sens SMS proved to work. I've then unplugged TC35 from power and then connected it back and now it works normal. Only god of electronics and mights of circuits know what the hell is going on there.

So for know only SIM900 still doesn't work.


texts: Calculate power given PSD and bandwidth?

texts:
Given the spectral recommendation for an Asymmetric Digital Subscriber Line (ADSL) below, I'd like to calculate the power in Watts that a modem would have to emit for the upstream band. I want to do so for the purposes of determining the maximum signal voltage (based on a standard 100 \$\Omega\$ load) that would need to be transmitted in order to determine bit requirements.

I thought that to get power I should multiply the PSD by the upstream bandwidth as

\$PSD \times bandwidth = 37\frac{dBm}{Hz} \times129349.125Hz = 4.786\times10^6 dBm \$

And then convert \$dBm\$ to \$dB\$

\$dBm = 10log(\frac{power}{1mW})\$

\$\frac{power}{1mW} = 10^{\frac{4.786 \times 10^6}{10}}\$

I'm making a logical mistake somewhere because those numbers end up being way too large. It's probably very silly but what am I doing wrong here?

edit: mistake I made was to not convert from dBm to watts first. Calculation works out correct using \$PSD \times bandwidth = 10^{\frac{-37}{10}} \times129349.125Hz = 20.65 dBm \$


texts: Not able to figure out how to solve this as \$I(s)\$ is used in the feedback

texts: I am not able to figure out the approach to this problem because \$I(s)\$ is connected to feedback instead of \$V(s)\$


texts:
I am reading a survey. In that survey the author talk about "Temporal diversity" I can guess what is the meaning of that. But he also announce one way of making Temporal diversity is

  channel coding in conjunction with time interleaving

and he also continues

  ... the information is coded first and then dispersed in different
  coherent periods over time

what is the meaning of

  ...then dispersed in different coherent periods over time


texts:
I have been having issues with my AVR USART. Using a PL2303 USB adapter with the following connections to the AVR

What I am seeing is

Garbage data (mostly of 0xFF or 0xF7 or 0xE7) even when the circuit is turned off (output below in HEX)

FF FF 7F 7F FF FF FF FF F7 F7 77 F7 FF 76 F6 FF F6 B7 FF FF E7 77 7F
FF EE FF FF 76 FF F7 F7 FF FB F7 FF FF FF F7 77 37 F7 77 FF 77 F7 FF
FF FF F7 FF FF EF F7 7F 7F 77 77 FF 77 FF 77 F7 7F 6F FF FE FF 7F F3
E7 FE E7 FF 77 FF 9F DF 94 EE FF FF EB BF FF 27 DA FF B7 FF FF 7F 6C
B9 FF 6F 6F 7F FF FE EF DB FF FE BF 74 FF F6 F7 F7 FF DE FB FF BF BF
B7 3F B4 FB 7F 6F 7F

When the circuit is on, this garbage data is interleaved with my regular output (below in ASCII to show my regular output interleaved with garbage)

Pro?yv2?[?o?[???rrent Time &n?m????????{??10:47:33
1/1/9???????????{3y 'm' &
'?'`???????????v<6>6{kk<11>s#?<3>????ow????o?????f<6>6{kk<11>s#?<3>??k??????????<27>?<3>accepted
??????????????n<22><27><27>+??+#`

This happens randomly. Somedays it would happen, then go away on its own and then come back again.

I am using 16 Mhz crystal. Baud rate 38400, Data 2, Parity None. USART mode asynchronous


texts: Can we replace the pulse transformer with some other circuit element in this circuit?

texts: Our research group was trying to simulate and analyse this circuit. But it seems that the pulse transformer is creating the problem in the sense that we cannot find its models in Pspice, microcap or any other such softwares. We would be grateful if you could help replace the pulse transformer with some other circuit elements or any possible suggestions.


texts: confusion regarding bias voltage of a transistor

texts:
"this dc voltage is known as bias voltage and it's ...regardless of the polarity of the signal source"
now I have this question :
**1.**Do i manually need to choose bias voltage so that so that transistor remains on even when negative cycle kicks in? for example let us say my signal source has value of 5 volts peak to peak , so now if I choose 7 volts or 12 volts as a bias voltage it should work perfectly, this also means that the bias voltage is not unique , it depends on the signal we are applying, we can change bias voltage according to our source signal, is it correct? (assuming everything is sine wave)


texts: Differential signals passing within 6 mils of ground vias?

texts:
It's puzzling I couldn't find the answer to this in the top 3 pages of google results.

I've got 4 DIMM240's routing to a single LX150 fpga.

Crowded in other words.

I'm supposed to keep 20 mils from anything else.

But can I pass within 6 mils of a ground via?

How about a +1.8V via, the voltage of the signal?

Speed is only 1600Mz for the data signal changes.

But if it would be bad for faster, I'd like to understand that.

Each differential has it's own ground plane adjacent to it.  3.5 mils away, or 8 mils away if it's embedded.

Thanks!


texts: Clocks setup when programming Atmel via ISP?

texts:
When programming an Atmel microchip over SPI (ISP), what external clocking do I have to provide to programee? Does it have to match programmer's internal clock frequency, or can be totally different because SPI CLK line will be used? If the latter, then are there any limitations on SPI CLK freq I will use on programmer, or will programee auto sync to whatever goes? Also, do I maybe need to disconnect any possible external clock from programee? Also, do I have to set any freq fuses on programee?

I'm newbie to EE, so I'd be grateful for thorough answers.

(For programmer I intend to try using a Raspberry Pi's SPI interface)

edit: uh, yes, I mean an AVR microcontroller, sorry and thanks.


texts: what is the number of turn of my secondary and primary coil?

texts:
I want to make a 800-1000w transformer for ips. I have bought all component to make it.
here is the list.

CABLE:-
SWG 21 for primary winding,
SWG 12 for secondary winding,
CORE:-
4.5 inch
FORMER/bubbin:-
3.05"/7.747c.m.
1.6"/4.064c.m.

The transformer is make by 12-0-12V secondry and 0/N-140-220-260V
Plz help me to find out how many turn will be in primary winding and secondary winding


texts: Is a microwave's output power proportional to the mass of its contents?

texts:
My friend and I are having a heated debate.

On the one hand, he thinks that a microwave oven that is empty, consumes almost no power (not considering lights, lcd, etc). He says that once you put an item in the oven, such as a glass of water, the oven will begin to consume more power as the magnetron must output more energy to heat the contents. Basically, he says that the power consumption of the magnetron in a microwave oven is directly proportional to the mass of heat-absorbing molecules inside the oven.

On the other hand, there is me. I think that the magnetron is always outputting what it's rated for (in an ideal world). I believe that an empty microwave simply dissipates its energy as heat through the chassis. I made the analogy of a radio tower that when transmitting, is always doing so at the same power regardless of the amount of listeners.

Both of us have come up with some interesting arguments, but neither of us are engineers and lack the knowledge to prove our theories.

So we turn to you!

Thanks!


texts: How to prevent square wave oscillation circuit from producing backwards sawtooth shapes in LTSpice4

texts:
In a related question, "simple, energy efficient circuit to make single IR LED blink", the following circuits are shared in the (current) third answer:

I entered these into LTSpiceIV and the output is unstable, sometimes producing a nice square wave, and other times producing a backwards sawtooth ramp-down shape.

What is really going on here?  I am a software developer trying to learn analog electronics, and have been playing around with the Joule Thief and other oscillating circuits, as well as trying to learn about SMPS converters, and would like to know how to diagnose and prevent unstable behaviors like this one in general, but I do really want to know about this one in particular.  If I had an oscilloscope, I would build these and try to play with them.

Below is a screen shot showing lots of the backwards sawtooth wave shapes, using 2N2222, 2N2907.

I also tried different transistor-pairs; 2N3904, 2N3906 and 2N4401, 2N4403 were better, but still had problems.

What follows is the contents of the LTSpice-IV *.asc file, so you can paste this into a text file and name it with an ".asc" extension, and then you should be able to (on a PC) directly open it up in LTSpice IV and run the simulation to reproduce what I am experiencing.

Version 4
SHEET 1 1584 680
WIRE 352 -64 -176 -64
WIRE 512 -64 352 -64
WIRE 352 -32 352 -64
WIRE -176 0 -176 -64
WIRE 16 64 -16 64
WIRE 240 64 80 64
WIRE 352 64 352 32
WIRE -16 112 -16 64
WIRE -16 112 -48 112
WIRE 240 112 240 64
WIRE 288 112 240 112
WIRE -16 144 -16 112
WIRE 16 144 -16 144
WIRE 240 144 240 112
WIRE 240 144 96 144
WIRE 512 144 512 -64
WIRE -176 160 -176 80
WIRE -112 160 -176 160
WIRE 240 176 240 144
WIRE 272 176 240 176
WIRE -176 240 -176 160
WIRE 32 240 -176 240
WIRE 352 240 352 160
WIRE 352 240 96 240
WIRE 352 256 352 240
WIRE 512 272 512 224
WIRE 512 272 464 272
WIRE 464 304 464 272
WIRE -48 368 -48 208
WIRE 352 368 352 336
WIRE 352 368 -48 368
WIRE 512 368 512 272
WIRE 512 368 352 368
FLAG 464 304 0
FLAG 272 176 C1
SYMBOL voltage 512 128 R0
SYMATTR InstName V1
SYMATTR Value 4
SYMBOL pnp 288 160 M180
SYMATTR InstName Q1
SYMATTR Value 2N2907
SYMBOL npn -112 112 R0
SYMATTR InstName Q2
SYMATTR Value 2N2222
SYMBOL res 112 128 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 1K
SYMBOL cap 80 48 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 10nF
SYMBOL cap 96 224 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C2
SYMATTR Value 10µF
SYMBOL res -192 -16 R0
SYMATTR InstName R2
SYMATTR Value 330K
SYMBOL res 336 240 R0
SYMATTR InstName R3
SYMATTR Value 22
SYMBOL LED 336 -32 R0
SYMATTR InstName D1
SYMATTR Value LXK2-PW14
SYMATTR Description Diode
SYMATTR Type diode
TEXT 8 -24 Left 2 !.tran 60s startup

Finally, I entered in the second circuit, which is just the first circuit inverted and polarity-switched, but it won't even oscillate.


texts: Using two switches to light/turn off consecutive LEDs

texts:
I am trying to create a circuit that controls 10 LEDs with two momentary switches. Let's call one button ButtonUp and the other ButtonDown.

When I press ButtonUp, the first LED lights up. If I hit ButtonUp again, the second LED lights up, etc., resulting in all LEDs being lit if you hit ButtonUp 10 times.

If I press ButtonDown, the most recently lit LED turns off.

Is there a way to do this with a circuit and if so, how?
Is this a job better-suited for a programmable chip like the one found in an Arduino?


texts: Keil watch window and Clock of STM32f103

texts:
Here is my public variable definition and value:

As you can see in this picture I can't track the value of Hello variable:

I have changed the position of Hello variable to prevent from being constant during the execution time.

but it still has two problems in debug mode( The data-type is different, "Cannot evaluate" error")
In addition, the break-points option is disabled in debug mode.

In addition, I need to know that the frequency of my MCU has been changed correctly to 72Mhz?

RCC_HSEConfig(RCC_HSE_ON);
while(RCC_WaitForHSEStartUp()==ERROR);

FLASH_SetLatency(FLASH_Latency_0);

RCC_PLLCmd(DISABLE);
RCC_PLLConfig(RCC_PLLSource_HSE_Div1,9);
RCC_PLLCmd(ENABLE);

while(RCC_GetFlagStatus( RCC_FLAG_PLLRDY)!=SET);

FLASH_SetLatency(FLASH_Latency_2);

RCC_ClockSecuritySystemCmd(ENABLE);
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
RCC_HCLKConfig(RCC_SYSCLK_Div1);

while (RCC_GetSYSCLKSource() != 0x08);
SystemCoreClockUpdate();


texts:
Using an STM32F429I-DISCO board. SYSCLK is set to 180 MHz. I verified the value from MCO2 output pin, and it is spot on. Setting up GPIO_AF3_TIM9 channel 1, and need an output of 12.288 MHz and 50% duty cycle. Calculated config values as:

  const uint32_t TIMF =  180000000;
  const uint32_t TFOUT =  12288000;
  uint16_t ARR = (TIMF / TFOUT) - 1;
  uint16_t uhPrescalerValue =  ((SystemCoreClock) / TIMF) - 1;
  uint16_t pulse = ARR/2 + 1;

Results are prescalar = 0, ARR = 13, pulse = 7.

Here is the setup code:

  GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  GPIO_InitStruct.Speed =  GPIO_SPEED_HIGH;
  GPIO_InitStruct.Alternate = GPIO_AF3_TIM9;
  GPIO_InitStruct.Pin = GPIO_PIN_CHANNEL1;
  HAL_GPIO_Init(GPIOE, &GPIO_InitStruct)

  TimHandle.Instance = TIMx;
  TimHandle.Init.Prescaler =  uhPrescalerValue;
  TimHandle.Init.Period = ARR;
  TimHandle.Init.ClockDivision = 0;
  TimHandle.Init.CounterMode = TIM_COUNTERMODE_UP;
  if(HAL_TIM_PWM_Init(&TimHandle) != HAL_OK)
  {
    Error_Handler();
  }

  sConfig.OCMode = TIM_OCMODE_PWM1;
  sConfig.OCPolarity = TIM_OCPOLARITY_HIGH;
  sConfig.OCFastMode = TIM_OCFAST_DISABLE;
  sConfig.Pulse = pulse;
  if(HAL_TIM_PWM_ConfigChannel(&TimHandle, &sConfig, TIM_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }

Output on scope counter shows PWM frequency as 12.8582 MHz. Duty cycle is correct. Where have I gone wrong in deriving the parameters?


texts: Does using 220V-110V transformer matter?

texts:
An electronic device manufacturer, said that using it with transformer is not recommended.

I don't understand why is that. There are products that work with both voltages, and I don't understand how the output of a transformer will be different from an "original" output.

Is that really true? If so, why is it?

The device is a singer sewing machine, which I want to use in the USA and in Europe, with different power outlets.

Even if regular transformer wouldn't work, I'll be glad to hear about other solutions.


texts: Create a blinking LED circuit with a z-diode and a capacitor

texts:
I was searching for the most simple LED flashing circuit. On a webpage (http://cappels.org/dproj/simplest_LED_flasher/Simplest_LED_Flasher_Circuit.html) I found the following circuit with a transistor and a capacitor.

As I read the description to the circuit, I was wondering, if it would be possible to swap the transistor with a z-diode, because the z-diode also uses the avalanche effect like the transistor in the circuit.

Would the ciruit below work ? And if yes, how would you have to calculate the values for the z-diode and the capacitor ?

simulate this circuit – Schematic created using CircuitLab


texts:
I have been designing boards (2-6 layer). After the complete layout I usually pour a GND in the end all over the board. What are the rules governing ground pours ?
In my 1st board I have 2 BLDC motors taking in about 16-20 amps. So having a gnd pour with vias stitched help in heat dissipation.
But my new board consumes only about 7mApms and it has a GPS.
Will a ground pour affect the performance of this GPS ? Is my understanding of ground pours clear ? Or is there any other advantage of ground pours ?

I understand that I should isolate the noisy Ground from the digital gnd. Is it ok if I route the noisy ground and digital ground seperate and then stitch them at a single point via a 0R resistor or a ferrite bead ?
Is this a good design practise ?


texts: Transformer Design: How do I set an N1/N2 ratio by means of selecting winding inductances?

texts:
I'm trying to simulate a transformer by using a circuit simulation software. In my requirements sheet, three specifications are given for the transformer:

Maximum power (\$P_m\$) of the transformer will be 4VA.
Magnetizing inductance (\$L_?\$) will be 30\$\mu\$H.
\$\frac{N_1}{N_2}\$ ratio will be 4.

(I don't know what "magnetizing inductance" is. Is there a term like that? Can it be mutual inductance (\$L_m\$)? Are \$L_m\$ and \$L_?\$ the same parameters?)

The turns ration must be a function of these parameters, isn't it?

Like:

\$\frac{N_1}{N_2}=f(P_m, L_1, L_2, L_m)\$

Where;
\$L_1\$: Inductance of the primary winding.
\$L_2\$: Inductance of the secondary winding.

My simulation software does not allow me to directly set \$\frac{N_1}{N_2}\$ ratio. Instead, it allows me to set the \$L_1\$, \$L_2\$, \$L_m\$ parameters.

So, my question is, how do I indirectly set the turns ration (\$\frac{N_1}{N_2}\$) by choosing \$L_1\$, \$L_2\$ and \$L_m\$ parameters?


texts: Suppose I have some sensitive proprietary software (VHDL/Verilog) on an FPGA connected to my server so I can control it by SSH. Now suppose an attacker compromises my server and can communicate with the FPGA. Could the attacker read the sensitive software off of my FPGA?


texts: Comparing two variable voltages with hysteresis

texts:
All of the designs I have seen for adding hysteresis to a comparator (Schmitt triggers) assume that one of the two inputs to the comparator is set at a fixed reference voltage (typically with a voltage divider between the supply voltage and ground).

Suppose I want to compare one voltage to another, where both input voltages change over time. A simple comparator will do this. But I would like to add hysteresis. In other words, when the difference between the two inputs is within some threshold of 0, the comparator does not switch its output, but if the voltage difference exceed the threshold, the comparator input switches to indicate which value is higher.

How could I design a comparator which compares two variable voltages with hysteresis?


texts: Low-power solar cell source using capacitors

texts:
I am designing a circuit using AtTiny10 to supply a downstream microcontroller with power using only capacitors and a small solar cell. Would the following design work ?

The basic idea is that the tiny10 gets powered directly by the solar cell (should consume around 40uA @ 3V internal 128kHz oscillator when active, datasheet here). The tiny10 controls one mosfet for charging the caps and one mosfet to connect the caps to the downstream microcontroller (not depicted here in the schematic, connected to +3V3 and GND).

Any comments would be greatly appreciated.

Many thanks in advance!

UPDATE: I have removed the pullup on /Reset since it sinks a lot of current. Assuming a 10kohm pullup @ 3V, it would mean 300uA wasted instead of charging the caps. /Reset needs to be disabled in the fuse bits.

Schematic:


texts:
MATLAB has a function fixdt() that creates objects describing fixed-point or floating-point data type. So if we write

a = fixdt(0,16,26)

MATLAB will return

  NumericType with properties:

      DataTypeMode: 'Fixed-point: binary point scaling'
        Signedness: 'Unsigned'
        WordLength: 16
    FractionLength: 26
           IsAlias: 0
         DataScope: 'Auto'
        HeaderFile: ''
       Description: ''

My question is, is it even possible to have a fixed point data type, with fraction length exceeding the word length. Doesn't the fraction length represents the location of the binary point from LSB? I'm trying to fully understand what exactly a data type of word length 16 with fraction length 26 exactly represent. Many thanks for your inputs!


texts: Load cell amplifier inverse voltage output

texts:
I'm making a load cell modification to my Logitech G29 brake pedal.
The potentiometer on the existing pedal have inverse voltage so 5V is no brake applied and 0V is max brake applied.

This is inverse of what for example an INA122PA amplifier does.
So I added an MCP606 to inverse or reverse the voltage from this post. I do not know what the correct term is as I'm not an electrical engineer.
The reason I need to do this is I am using it for the PS4 where I cannot reverse the axis of the pedal as I can on PC.

So I made the attached schematic in KiCad. I added a variable resistor to the output so I can modify the gain.

So my question here is are there some parts I do not need?
There are two caps going from 5V to ground (C1 and C2), do I really need them or is one enough? Also added a bypass of the MCP606 to get the output from the INA122PA

Do you now of a load cell amplifier that has inverse output builtin, haven't been able to find any.


texts:
I am using MAX5035 for a DC-DC(5V output, 9-72V input) converter.

The circuit works fine for 7.6-20V input. The output begins to rise for input above 20V.

Please suggest reasons for such a response.


texts: Off grid LED solar lighting without batteries

texts:
I have 2 COB LEDs (12-14V DC, 50W, I think with 3,75 A in data sheet). I need to run them with a solar panel, it should only run when there is sunlight no batteries needed. Using a 270W panel (open circuit voltage around 38,8V, optimum volt and current: 32V, 8,4A) with 2 parallel connected DC DC Step Down Buck Converters 8-40V 10 or 12A Constant, adjustable current and voltage to run them both separately, it is concerning because the maximum voltage of the solar panel gets really close to the maximum current the Buck Converters can handle.

Using only one LED with a 130 W Solar panel (open circ. volt 22,8V, opt. volt+curr: 17,6V 7,4A) with a 7-32V DC DC step down buck Converter 8-10A also constant adjustable current and voltage. It is concerning that the input voltage may get to low for the converter (because just 38% of the current of the max. output is needed and because the voltages get lower when the temperature gets over the 25°C Standard-conditions.) Which means bad efficiency when there is no perfect sunlight shining.

Or are my concerns unfounded

Please help…

Thank you very much for your answers. I already got the LEDs and the Solarpanel

I got the idea to try it with a buck/boost converter (link) to hopefully solve the voltage problem that comes with a 150W Mono solar cell at higher temperatures (shift down to almost 12V in the worst case (75°C and 0,3-0,4% irridiance)), what do you guys think does it work better that way than with a buck converter?
So in this way: Solar panel -> Buck Boos converter -> LED

I mean the Buck boost converter only costs about 3$ so...
Instead of a Buck converter.

higher voltage, lower amps mean less heat, so there Comes another Advantage with a buck boost converter i guess, because I can go higher with the voltage as I thought (13,5 instead of 12,5V with the buck converter to slightly better handle the temperature-caused voltage Drops) And for the Buck Boost Converter it should be of no or little concern if 13,5 or 12,5V are adjusted because it can both, also a Switch of the converter just stays opened when it gets the same vin as vout is adjusted, am i right? just the current gets witheld in that case)

OK thank you i now ordered a Automatic Buck-boost converter but you are right a mppt Charge Controller (that i have to adjust?or is it enough to connect the battery first with the chargecontroller? ) and a small battery would be better for more continous LED lightning. I found this one https://www.ebay.de/itm/12V-24V-30A-MPPT-Solar-Charge-Controller-Solar-Panel-Battery-Regulator-Dual-USB-/283300643163
... In combination with a small 12V 20AH solarbattery..?
But first i will try it Out without battery so heres my First Plan:
So do you think it works out when i Just wire the 150 W Solarpanel (21,8V opencirc. V) with the Buck-boost converter (How about the polarity of the voltage with buck-boost converters i think i did not fully understood this till now will/can it work too with a combinated step Up/down module instead of a normal Buck converter?) and then to the one cob led that is mounted to an Aluminium heatsink? I also ordered two Buck converters to experiment.

Here are the links to all the articles that i ordered to make it complete:
BUCK BOOST CONVERTER 5-30V
https://www.ebay.de/itm/Automatic-Boost-Buck-Converter-CC-CV-5-30V-To-1-25-30V-8A-12V-24V-Regulator-100W-/132951586178?txnId=1566909161003

BUCK CONVERTER CC CV 7-40V
https://www.ebay.de/itm/DC-DC-Voltage-CC-CV-Buck-Konverter-7-40V-to-0-8-28V-12A-300W-12V-5V-AHS-/302978096967?txnId=1612434223020

BUCK CONVERTER CC CV 7-32V
https://www.ebay.de/itm/DC-DC-CC-CV-Buck-Leistungsmodul-7-32V-Zu-0-8-28V-300W-Konverter-Step-down-DE-K1-/332974029848?txnId=1632235338014

12-14V 3,75A LED:
https://www.ebay.de/itm/10DC12V-50W-COB-LED-Full-spectrum-400-840nm-High-Powe-Grow-Light-for-hydroponics-/263123281373?txnId=2387191590016

SOLAR:
https://www.ebay.de/itm/55516-Solarpanel-Solarmodul-150W-Solarzelle-12V-Solar-MONO-/362500588745?txnId=1011911505023


texts:
For an trajectory estimation project using BMX055 IMU, it looks like all 3 sensors(acc,gyro,mag) inside the IMU have different and unsync data rates. Accelerometer provides 7.81, 15.63, 31.25, 62.5, 125, 250, 1000, 2000 Hz options. Gyroscope provides 100,200,400,1000,2000 Hz and magnetometer 2,6,8,10,15,20,25,30 Hz rates. Considering a dead-reckoning application using a fusion algorithm:

Is there a relationship between the case that sampling rates are exactly multiple of each other and algorithm's(mahony,madgwick,kalman,dcm..) success?
If 125Hz for accelerometer and 100Hz for gyroscope are selected, what speed the fusion method need to work?  Selecting 100Hz and discarding 25 accelerometer sample or selecting 125Hz and repeating 25 gyroscope sample when running the algorithm.
Sensors sampling are not sync with each other. Does it cause a problem for fusion?
How to select data rate(bandwidth) of IMU sensors with considering application? Can we say higher sampling rates are better everytime?


texts: Electronic Controller Unit (ECU) Vs. MCU

texts:
Isn't the Electronic Controller Unit (which are used in automotive applications) a Microcontroller it self?

What is the difference between them in architectural point of view?


texts: How can I use 5V devices and sensors with a Fio?

texts:
I have a PS/2 barcode scanner that works fine with my Uno and the PS2Keyboard library. I'd like to hook it up to my Fio so that I can transmit barcode readings wirelessly, but the operating voltage of the Fio is 3.3V. I tried giving the scanner 3.3V, it will not operate on the reduced voltage.

How can I use 5V devices and sensors on the Fio? Would a boost converter circuit be sufficient?


texts: How to determine temperature with LSM303DLHC

texts:
I am using a LSM303DLHC and am very confident I have the I2C communication working well.   I am now trying to use the devices 12 bit temperature sensor.  The datasheet is not clear and the tech support is not that fast.

The datasheet parameter, TSDr, described as "Temperature sensor output change vs. temperature"  has a typical value of "8 LSB/°C".

That seems to suggest to me that a temperature reading of 1 (just single bit high) would be 1/8th of 1 deg C.  A value of 8 would be 1 deg C.

That does not work out over a range of temperatures.  I don't have access to an accurate thermometer, but it it's clear it'd not as simple as that.

Hoping someone reading this might have already figured this out.


texts: What are the differences between buffered/unbuffered clocks in a Virtex-6 FPGA?


texts: Why does a CCFL in an LCD have a bigger pink lead and a small white lead?

texts:
After removing the dead CCFLs from an LCD monitor, I noticed something odd. Although both wires go to different ends of the tube and presumably carry identical currents, they are visibly and internally different sizes. Everything I know about electronics tells me the current is the same in all parts of a circuit for a series circuit, but this defies that!

See picture attached.


texts:
I can use your help.
I need a high precision capacitor to implement the RC match filter across an inductor to measure the current through it.

Picture taken from (IC is not relevant in this question): http://www.ti.com/product/LM27403/datasheet/detailed_description
You can imagine that the capacitor needs to be very precise in order to effectively match the L/DCR of the inductor to the R*C time constant.
What I'm asking is, can you recommend any material or type of capacitor that I can use the best. [Deleted own requirements, question will be obsolete for others]
I know that this technique is not rock solid because of environmental influences, that why a high precision capacitor here is mandatory.
Thanks for your time and support :)


texts: How to use 18650 instead of A23 battery to power 12V door/window sensor

texts:
I have a security/alarm system running, it uses multiple door/window sensors (433Mhz), which use A23 12V batteries. These A23 battery are non-rechargeable and quite low on capacity (used in 433Mhz remote controls as well), they are drained after about 3 month when installed in the mentioned door/window sensors and I'm sick of buying new and replacing every so often.
I'd like to use a single 18650 battery to power a sensor (salvaged from old tech with higher capacity, should be enough for 1-2 years). So I tried a small step-up converter but discovered that it draws ~1mA without even the sensor being attached. This would drain the battery after ~2000 hours (80 days), so I end up with even shorter time on the 18650 battery.
Wrong approach? I searched the net, but end up with charge-modules and things, which do not help.
My experience with micro electronics is rather basic.
Thank you in advance! o)


texts: Need help understanding rise time parameter in nc7wz04p6x datasheet

texts: I am looking at the datasheet of nc7wz04 UHS dual inverter. The propagation delay specified is 2.3ns. The rise time/ fall time of input pulse in the fig 6 is 3ns. But in recommended operating conditions table, for 5V output, tr & tf is 25ns. What should be my input pulse rise time?


texts: Help regarding question of magnetic flux in 3 phase induction motor

texts: Here i have a picture where the waveform of magnetic fluxes of each phase is given . I know that the formula for resultant vector when magnitude of two vectors are same is 2.F.cosx/2 where F is the magnitude of equal forces(flux in this case) and x is the angle between two forces.but here i got the question:at interval 0 In the picture flux of phase 1 is 0 so we only have vector sum of 2 other phases. You can see that in the equation for resultant flux the cos of 60/2 is taken. Why is it so? Isn't it that the flux should lag by 120 ? So that we should have cos120 ?please explain this concept to me. I am good at math but i cant visualize how it actually works.


texts: Where should I put the kickback diode in a transistor switch?

texts:
When driving inductive loads with transistors, we use kickback diodes.

What I understand is a kickback diode supplies a path for the inductive charge to discharge. Also, an inductor will try to resist the change in the current, turning into something like a voltage source that will source the current in the same way it was before, in case of a break in the current (for example  when the transistor turns OFF).

In the below circuits, there are two different placement of the kickback diode. D1 is placed in a logical way, so that the charge in L1 will discharge through it, protecting Q1's collector from over-voltage or breakdown.

However, the second circuit with D2 makes no sense to me. How can D2 prevent any damage when it is reverse biased? I was seeing this configuration rarely, however I saw it in a Lenze driver schematic and couldn't understand it.

How does D2 prevent any damage due to inductive kickback?


texts: logic level converter does not get to 5v

texts:
I'm trying to control a 2 relay module with an Esp8266 esp 12-f.

After a while, I realized that the GPIO from the ESP8266 was not going to drive the 5v needed for the relay to be activated. I only get the relay module led turned slightly on, but I don't get the relay activated.

I tested the relay and it works if I control it with an arduino or even with a direct 5v in its IN1/IN2 inputs.

That's why I bought a Logic Level converter, which turns my 3v signal into a 5v one.

How I set all up

Here's a schematic of what I set up for this. (I don't know how to add components to fritzing, so this is just to get the concept of what I've done)

Everything is powered by a 5v USB and the 3v part of the Logic Level is powered from the ESP8266 3v pins

I'm using the GPIO14, but also tested with the GPIO 4.. not sure if there's a difference there.

The problem

After setting that, I can see that the blue wire, this is where my 5v signal should be, gets a 3v instead. And that's my actual question:

Why my converter won't convert my gpio14 3v to 5v? What am I doing wrong, or is it the converter that's fried?

I'm testing this with a multimeter. And of course, this means the relay is not triggered.

Let me know If I can provide anything else, any help is appreciated. May be i just need to buy a new converter?

Thanks a lot!


texts:
I'm working with an Altera FPGA. In the Pin Planner there is a choice in the combo box for a 1-bit inout node to be connected to an "IOBANK_n" (under "Location" row). I was expecting only "PIN_nn" are available.

What does it mean to connect a 1-bit node to an IOBANK? or, if it's nonsense, then what type of objects do you connect to IOBANKs?


texts: What is the noise electrical appliances / lights make before the power goes out during a blackout?

texts: I have no prior EE experience, but I am curious about why there is a strange noise when a blackout occurs. It makes a high pitched noise right before the lights fade out? What causes incandescent lights to make the noise while the lights are fading out?


texts:
How can I wire up 6 pin potentiometers for 3 pins.
I need a 3 pin potentiometer for a project, but I only have 6 pin ones available, how can I hook it up to a LED or volume control circuit?


texts:
I am using a  CTHSCIC06 capacitive touch button and have connected as per the datasheet  (the motor side of the circuit is not needed) however I am still having trouble around the pnp side of the circuit. I am using the BC557C. The circuit is set up in the following configuration:

simulate this circuit – Schematic created using CircuitLab
The idea with the button is that when the button is pushed the LED will turn on and will give a +5V logic signal to the MCU. When the button is not pushed the led is off and the logic signal is 0V.
I have this soldered onto prototype board and it works fine when the power supply is from the USB connection from the PC to the ardunio however when I connect a power supply with +5V even when the the pnp is suppose to be off, there is still a low to medium glow from the LED within the capacitive push button as if it is on. But from probing the MCU I/P when the low medium glow is present it is 0V going to the MCU. So it seems when the LED should be off, it is still on but not on fully.
Originally I thought maybe voltage ripple but the ripple on the power supply is no more that 15mV. I also thought maybe the pull up resistor isn't pulling the line high but this works when powered from from the PC usb.
If you guys have any suggestions or advice that would be great.
Cheers
UPDATE
So I checked the voltage of the MCU O/P pin and found when powered from the USB V=4.8V but when powered from external power supply V=4.1V. Could this be a reason why the line is not going fully high?


texts: Guarantee Continuous conduction mode dc/dc buck converter

texts:
In a buck converter the continuous conduction mode it depends on following equation:

$$ L_{min} \geq \frac{(1-D)R}{2f_s} $$

For a fixed load and inductance value, the operation mode will depend on the switching frequency.

For  following specifications:

$$ V_i = 30V $$
$$ R = 6\Omega $$
$$ L = 43 \mu H$$

I made the following plot:

Where yellow line is the output current, and the curves represents the minimum current required to operate in CCM at a given frequency. According to that, any Fs over 100 kHz will guarantee CCM in all range for that specific load and for any bigger one.

To find the minimum switching frequency to operate in CCM search iteratively the frequency where the line and the curve is tangent ang got: Fs = 70859Hz.

Is this a proper way to approach this problem or there is a better/easier alternative?


texts: Pulldown doesn't seem to affect inverter?

texts:
I have a relay/optoisolator circuit which is connected to a microcontroller.

The input/output is controlled by a physical slide switch.

I expected this to turn off the relay and status light because of the 10K pulldown, but the status LED stays on when I switch to the input side.

What am I missing?

The relay is a SIP-1A05.


texts: Very simple signalling over 12V DC power wire?

texts:
I found some DC power line comms circuits but they seem too complex for my needs. I have 6 outside LED RGB lamps that are linked with a single 2 core cable running around the edge of my garden, it is about 20m (60 yds) from the 12V DC power supply inside garage to last lamp in the chain. Each lamp is rated at 10w so max 60w from PSU means 5A max current. The lamps are controlled (on/off, colour, fading, etc.) by a small IR remote that only has a range of about 2m (6 ft), the IR goes through the lamp lens to an internal receiver. I want to be able to control all of the lamps together from a single remote. I have tried building a larger IR remote using 24 IR diodes and a 9V battery and this works to a degree, but still does not have enough range.

As the lamp housing is large enough to hold a further small circuit I thought that maybe I could add a small IR receiver inside the lamp and send the required signals over the 2 core DC power cable. I would put an RF receiver inside the garage and drive this from an RF remote (much better range), the RF receiver would need to send the signals to the lamps over the 12v power cable which each receiver would resend as IR within the lamp, so IR range is no longer an issue. Ideally the receiver would not consist of more than a few passive components and probably at least one transistor and an IR diode. Perhaps an FSK carrier at 100KHz on the DC line, carrier present = 1 (IR on) and no carrier = 0 (IR off).

I normally work with micros so my logic skills are fine but my RF and discrete skills are not very good. I want a simple solution, assuming one exists, otherwise I might just have to go back to building the mother of all IR remotes.

Update - I like the DCC solution suggested and on checking I see that the LED lamps are in fact rated as 12V DC/AC and so must already include a rectifier within them. I will monitor the IR signal to find out what the duration of a 'message' is how long each bit is. I have some IR LEDs rated as 1.5V 20mA so if I put one of these in series with a 560R resistor across the power lines inside the lamp then it should turn on when the power lines have the correct polarity. Can I assume that the LED will be safe when the polarity is reversed or does its high reverse resistance mean the entire 12V will be across it and damage it?


texts:
I'm trying to figure out the meanings of all the parallel port IO addresses on a PC because I have custom hardware I use with it and I figure if I change a value then my hardware will work.

So far, the Internet tells me that the standard IO port 0x378 is data, 0x379 is status and 0x37A is control.

On my linux when I have the parallel port drivers loaded, I see the above IO port addresses but I also see these addresses:

0x37B through 0x37F

What do each of those addresses represent specifically?


texts: Is it better to make multiple small i2c requests or one larger one?

texts:
I have four registers on my slave (an arduino)

0x00 - device id
0x01 - button state (four buttons)
0x02 - led state (four buttons)
0x03 - led mode (how the leds react to button presses if at all)

Currently, to get a value off the slave I issue a write with an address. This address is stored in a pointer on the slave and then when the next read comes in I return the data in the register at that pointer address.

Basically, on address 0x48

W 0x48 0x01
R 0x48        ; button state at 0x01
W 0x48 0x02
R 0x48        ; led state at 0x02

And I do this over and over checking for state changes. I'm not really sure why I did it this way, some datasheet or blog post lead me in this direction but now I'm questioning it. Now I'm thinking I should just skip the writes and return all the register values on every read. So one read would return four bytes in this example instead of one.

Is this better? It seems less error prone but I'm not sure what costs are associate with returning multiple bytes etc.


texts: How to measure high power LED temperature?

texts:
I have a 100W LED module that I believe is overheating due to the heatsink being too small. I use a piece of anodised aluminium from an old fanless PSU. It's only 300g so far too small for 100W led so I added 120mm fan. I still feel it gets far too hot. I have an IR thermometer and it shows temperatures over 120C after a few minutes when measuring the led itself and 40C for the metal part of the led. Thermal grease in between but the led is not firmly fixed to the heatsink.

I am planning on using arduino with a basic temperature sensor to control cooling fan based on temperature and dim the led if it overheats. What is the correct way of measuring the temperature of the led and at what part of the led?

Here's the LED:


texts: 3 phase transformer efficiency calculation

texts:
This is an assignment. No matter how hard I try the answer is never what I expect. Here is the question:
Three single phase transformers, each rated at 12 kVA, 120/240V, 60Hz, are connected to form a three-phase, step-up, star/delta connection. The parameters of each transformer are
R(High) = 133.5 milli-ohms,
X(High) = 201 milli-ohms,
R(Low) = 39.5 milli-ohms,
X(Low) = 61.5 milli-ohms,
Rc(Low) = 240 ohms,
Xm(Low) = 290 ohms.
When it delivers the rated load at the rated voltage and 0.8 pf lagging, determine the line voltage, line currents and efficiency.
I will tell you what I am after. Here is what I did, but the answer is 0.92 approx. I think I am mistaken in calculating core and/or copper loss.


texts: Making eaglecad library for ATSAMD21G: how to copy TQFP48 package to my new library

texts:
I did look in the standard library for Eaglecad, but I see no entry for the SAM D chips.

While searching, I saw posts that say to make my own, so I did.

Now, I have the schematic for the D21G, but I need the footprint. From my understanding, I can use another TQFP48 package from another chip and that should be OK.

Is this true or do I have to do from scratch also the packaging? I am not sure if I would be able to do that from scratch; the sparkfun tutorial was not really clear.

I wish there were libraries already made for the components that I need, but sadly they are not. Design with Eagle seems to put hurdles after hurdles, in front of the newbies :)


texts: Proper way to connect signals to USB Type-C receptacle

texts:
I am trying to follow the design in this schematic link at page 9.

The schematic above is connecting only RX1 TX1 and D1 data lines on the USB-C receptacle. And there are no pins shown for the other pairs in the USB-C standard (RX2, TX2, D2).

Does this imply leaving the other pairs floating?

I only need my USB-C receptacle to properly transfer my RX, TX and D signals. And couldn't figure out what to do. I spent a lot of time Googling the matter. Using a MUX as TI's HD3SS3220 could be my best chance. But I really want to know if I can just leave these pins floating, voiding extra components.


texts: I was aiming to make a square wave generator which gives 16 kHz -7V,+7V square wave signal. I have used this design however i could not reach a clear square wave. I have shown the LTSpice simulation result and circuit below. If you have any idea, i will be happy. Thank you.


texts: Configurable Switchs Selector Identification

texts:
Probably off topic.

I need help identifying a switch type.

The switch in the picture is embed in a camera to define configurations to the hardware.

I would like to use this kind of switch in a project, but i need a light.


texts:
I need to make a precise angular rotator for my directional antenna. The goal is to rotate the antenna at a precise angle. Arduino stepper motor library has functionalities to run a stepper motor for one step at a time. However, the problem is to choose the right motor.

I need at least 1-degree precision. Therefore, I am thinking to use a 0.9-degree step angle stepper motor. The problem is I cannot decide what would be the right stepper motor for me.

The total weight of my system is 3 kg. There will be two directional antennas, each having 1 kg weight, in an antenna stand which has approximately 1 kg weight. I need to rotate the antenna at a specific angle and then make some experiments, and then go to the next rotation angle. Each time I need to achieve a precise angle so that the experiment can run correctly.

Now, what should be the right stepper moto for me? I can calculate the moment of inertia of my system (J). However, I do not know which torque would be sufficient to perfectly rotate this motor. That what should be the minimum angular acceleration (a) of my system to ensure a precise and smooth run of the system.


texts: Base resistance missing in BC817-40 datasheet

texts: I need to calculate noise at the base of my BJT so I need base resistance for that, but I could not find this parameter in any datasheet. How do I can calculate noise then? Do I have to measure base resistance on my own? If so, how? I am using sot23-5 BC817-40.


texts: What is the relation between DAC peripheral bus and conversion/settling time

texts:
Going through the datasheet and the LPC17xx user manual, what is quite evident is how to select the various clocking options for the peripheral clock divider, i.e:

00   PCLK_peripheral = CCLK/4
01   PCLK_peripheral = CCLK
10   PCLK_peripheral = CCLK/2
11   PCLK_peripheral = CCLK/8, except for CAN1, CAN2, and CAN filtering when “11” selects = CCLK/6.

But what is not evident is how various clock speeds impact the conversion time (or settling time) of the DAC output? Would CCLK / 8 result in longer settling times as compared to CCLK / 2?

In case if their exists no such relation and the conversion/settling time is only dependent upon the DAC BIAS bit (DACR[16]), then why did the designers even gave this option for choosing between different clock sources?

Please forgive me if i am asking something which is plainly obvious. ARM is a new architecture for me and i have searched through the available literature. I also checked out some tutorials but the question still remained unanswered.

CPU: LPC1768


texts: Can you receive a shock by touching only one probe ?

texts:
in this video at 4min 4sec
https://youtu.be/CkGVMWK10qU?t=243
The guy receive a shock of a taser by touching a metal object that touches one probe, but why does the arc goes through his body ? I know that there must be an electric potential difference in order to have current flowing through the body, so where is the second potential ? At first I though it was the ground he touches with his feets but his contraption runs on a drill battery and it looks like it is on a wooden table.
Any help ?


texts:
I designed this circuit;

PRI_LO and NEUT are connected to 220v.
The "high side" triac is Q4004D3RP (datasheet).

I measure voltage at J2.

Whatever is the command signal, I always measure 220v. I shorted the led of the MOC3041, same result. Why?

Second question, this system is triggered by an esp32. During a test, I unplugged the usb cable of the ESP32 and I noticed some electric arc on 220v side. I was unable to see exactly where. At this moment a smartphone charger was plugged in J2. Why?

Thanks


texts: what do I need to make 230V AC fan spin slower?

texts:
So - i often work with DC current for robotics and the like, but now i have the problem that i'm having a 230V AC fan which shall be operated at two different speeds for an exhibition installation. I don't have a dimmer, only two 230V relais that are controlled by my microcontroller and that are connected to regular 230V AC powersupply. At one setting, the fan should rotate at maximum speed, at the other setting it should turn only very slowly.

Now, I'm not experienced with AC current electrics. I think I have to put a capacitor in series with the fan, as a capacitor in an AC circuit is kind of the equivalent to a resistor in a DC circuit, right?

But what capacitor to chose and what to pay attention to so that the whole thing won't catch fire?

//edit: the fan uses a "Shaded-pole" type of motor

thanks!


texts: Should I cool off in water the desoldered components?

texts:
I use a REGULAR (for home-use, not for electronics) hot air gun to desolder non-SMD components from PCBs. The components are really hot (naturally) after desoldering and it takes a while until they cool off. Is it better or worse if I cool then off in water?

My issue is related to the fast cooling interval that will appear when I drop the hot component into the water.


texts: How to invert a sine wave so that the output is 180 degrees out of phase with the input?

texts: I'm sure there is fairly simply op-amp circuit that will do this, however I lack the experience to design it myself.


texts: How to implement Latch with WR/RD functions?

texts:
In a VLSI design book I have found a diagram of a (jamb) latch that is used in FPGAs as part of register file and I wanted to use it in the circuit I am designing. However I have a few qestions:

What is the triangle with a circle means? Never seen it before. Doesn't look like an inverter. How is it implemented in CMOS?
Now, the WR transistor and two RD transistors looks like they aren't following the Pull down / Pull up rules, is this ok ? If so , where do I connect the Vdd ? Is Dout going to ground?

Unfortunately the book only shows this circuit and no more explanations so if you can recommend me where I can read on latches that have Data-in/Data-out outputs and read/write switches it would be helpful because a simple set/reset latch isn't very useful for me, I need to work with Data input as it comes from the source (would it be high or low)


texts: Is it possible to combine Common and GND on a DC/DC converter?

texts:
There is an isolated DC / DC converter TMR1222

12VDC will come to the input,
The outputs will be + 12VDC and -12VDC

When connecting with dual output, there is a "Common" contact

Tell me, is this the earth? If so, why was it not called GND?

Can I connect Common to GND?

Thank you!


texts:
I'm using USB cables in an very unconventional way (don't ask, we had a barrel full of USB cables left over from something else) to connect between boards with 3v battery power and also not following the USB pinout at all.

And would like to place diodes behind the USB receptacle to prevent anything bad happening if someone were to be actually try plugging one into a computer.

Someone suggested this configuration, and my mental model of how diodes should work with separate voltage sources isn't strong enough to figure out how this would work, but I'm also not convinced this circuit looks right. What would actually happen if this were connected?


texts: When is one active and one dummy strain gauge preferred to two active strain gauges?

texts:
As far as I understand, one active and one dummy strain gauge arrangement can be used for temperature compensation. But even two active strain gauges can be used for temperature compensation, and in fact, the latter has better sensitivity.

Is there any situation where one active and one dummy strain gauge arrangement would be preferred over the two active strain gauge arrangement? Similarly, is there any situation where two active and two dummy strain gauges would be preferred over four active strain gauges?


texts:
I have a project to open and close a high voltage circuit (e.g. 240 V) with a relay using low power, let's say 5 V.

Is it possible that I can use it as a switch to on or off the circuit without providing it power (5 V) continuously to close the circuit?
I want to make an electric switch for 240 V which just takes 5 V for an instant to switch only. For example, if I have a 5 V battery I don't want it to drain continuously.
I want to make it like a toggle switch.

Or there are any other options I can use?


texts: How do you know if a vacuum tube is going to suffer from AC hum or not?

texts:
I know that technically there is little difference between AC or DC heating of the tube - if it gives proper voltage everything is fine... Except the hum:
  I have read in various sources that some preamp tubes are very resistant to AC hum and can be properly heated with it and some are somewhat terrible with the hum and are needed to be heated with filtered DC if you want to achieve noiseless performance.

The question is.. How do we know which types of tubes are affected by the hum and which are not? Can you find out without testing? I have researched various datasheets but found little help.
  The problem it appears is that in most datasheets it is not stated if the heater is isolated or not.  (Obviously an isolated heater will produce way less hum)

I plan on working with ECC85 tube (similar but not the same as 12AT7/ECC81).  (Maybe some of you had experience with this specific tube?)  In this tubes datasheet it is stated that it can be heated with both AC and DC but then again... if we are working on somewhat high-end headphones amplifier is the noise going to be an issue with AC heating? And how bad is it going to be?
Here is the datasheet:  https://frank.pocnet.net/sheets/010/e/ECC85.pdf

There is a wonderful source of information in this website  (tubes enthusiasts - you must read this! It's a gold mine) and it basically answers my question (use DC and you can not go wrong).
http://www.valvewizard.co.uk/heater.html

Of course you can always go the guaranteed road and filter AC to DC  (cmon, it's easy isn't it?) but I am really curious whether you always need DC heating for high end performance... And how do you find it? - the answer is still somewhat a mystery to me.


texts:
I need to detect a AC mains outage, isolated way. Output marked as [?] goes to AVR MCU. I don't need to detect undervoltage or zero-crossings. I actually need a simple feedback to MCU interrupt which will trigger interrupt only in mains outage. MCU are powered from UPS. I've picked following circuit found on the net based on PC817, but adjusted C1/R1 to 230VAC.

Any errors, i.e. will this work? Suggestions/comments on parts/values are welcomed.


texts: Long term storage of sealed lead acid battery

texts:
I was given some brand new sealed lead acid batteries. I have no real need for them right now, but I don't want them to go to waste. I'm trying to figure out the best way to store them, unloaded, for many years until I'm ready to use them for something.

Would storing them in a cool basement, attached to an intelligent float-charger work? When I say intelligent, I mean it monitors the voltage and cuts on and off to keep the charge topped off.

Approximately how long could I keep the battery stored like this and not have significant degradation?


texts:
There's a touch button which has a spring on the PCB.

Is it capacitive?
How does it work?
Do I need a special circuit to read touch events?


texts: Purpose of capacitor and diode in analogue input protection circuit of ADC?

texts:
I am analyzing the following circuit used as an analogue input protection for an ADC ( image source: http://www.analog.com/library/analogDialogue/archives/43-04/process_control.html ):

I don't understand the purpose of c5, c6, and D3. So my questions:

1- I'm guessing c5 can reduce spikes on the input. Is this correct?

2- I have no idea what D3 (1n4148) does. If a negative voltage is placed at the input of the circuit this diode would immediately fry (defeats the purpose of the circuit).

3- I also have no idea what c6 does?

4- Also the ref input is connected to 0.5 volts. Why? The op-amp is rail-to-rail, why is there any need to shift the output by 0.5 volts?

P.S. Anti aliasing filter is placed on the ADC input and is not shown in this circuit.


texts: Calculator Printer Control (how to drive Epson dot matrix printer)

texts:
I have small dot matrix printing device that I'm trying to control (i.e. print to) with a Parallax Propeller board.  (See images below.)  It's the printer from this: http://shop.usa.canon.com/shop/en/catalog/calculators/palm-printing-calculators/p23-dhv

Is anyone familiar with how one of these things works?  I don't see any chips or other electronics on it, so I assume it's just stepping motor control.  It seems like I can get specs on the large silver motor from here: http://www.standardmotor.net/sc_webcat/ecat/product_browse_list.php?lang=1&cat=205 but don't know on the rest.

It would be great if there were some sort of "driver" for this for use from Propeller Spin code, but I realize that most likely doesn't exist.  If I could at least find some specifications that would describe what I need to send to it, I'd be happy.  (Trying to guess what I need to send to each individual motor to get the right output sounds like a rather difficult way of approaching the problem, was hoping there was some sort of documentation or standardized "protocol" that might exist for the overall unit.   Definitely have googled a lot to no avail.)

Just looking for some help to point me in the right direction here.  I am familiar with the Propeller chip, software development (my main gig), and basic electronics concepts.  Never tried to do motor control before.


texts: Why is the capacitance changing while measuring?

texts:
I have 2 different 100nF capacitors. Let's call them A and B. My dad told me that B is "better" than A. I've tried measuring their capacitance using a Metex multimeter which has the option of measuring capacitors. I connected A and it showed 80nF and then it started slowly rising until it reached about 130nF. What's more, I've tried touching the capacitor (I was careful not to touch the terminals, I've touched only the coating). It influenced the result of the measurement - capacitance decreased. I thought that maybe it is related to the temperature but then I blowed warm air on it and it didn't change anything.

And then I connected capacitor B. It showed 100.5nF. I could touch it as much as I wanted and it didn't influence the measured capacitance. It was rock solid.

At first I thought that A is faulty but I have more capacitors of this type and all of them behave in the same manner. Why is this happening? Can I still use them e.g. as a Vcc buffer in an IC (like Atmega, etc.)?


texts: Demux I2C with a relay system or similar

texts:
I'm working on a electronic prototype. I have got one I2C communication master and I have six slaves to talk to. But here is the problem: the components are not built to have many addresses: only two are available.

So I have got two possible solutions:

The first is to program the processor to give me three I2C masters. This isn't very convenient.
The second one is to use a demux component which uses a mechanical connection between the slave and the master like a relay connection (classic demux are buffering signals).

Do you know of such a chip? Or is there another option?


texts:
I am trying to implement an idea where part of the register is incrementally taken, shift left twice and subtract one from the residue. Following is the piece of code I am working on. I am required to take Bplusone[0] in the first iteration, shift it left twice and subtract 1'b1 from it, then have zeros in the remaining part of the register. Then take Bplusone[1:0] on the next iteration, shift left twice, subtract 1'b1 and have zeros filling up the remaining part of the register. I am stuck here.
Here's what I have done:
I initialized the registers A, B and iteration count using Reset. Then used MUXs to perform some operation on the registers and had Aplusone and Bplusone as the outputs. Then incrementally take outputs from Aplusone and Bplusone, perform some operation on them, store it in registers F1 and F2 and finally choose from these to get the desired output in the register F. How do I go about with iplementing the process I described above?
input logic Clk;
input logic Reset;
input logic [1:0] sjplusone;
output logic [11:0] F;
output logic [7:0] Aplusone;

logic [7:0] K, A, B, Bplusone;
logic [9:0] F1, F2;
logic Kout;
integer iterator;

always @(posedge Clk) begin
    if(Reset) begin
        iterator = 1'b0;
        A = 8'b00000000;
        B = 8'b00000000; end
    else
        F1 = ~Aplusone << 9 - iterator;
        F2 =  (Bplusone << 9 - iterator) -1'b1;
        iterator = iterator + 1;
    end

    shiftreg #(8) shr (Clk, Reset, Load, 1'b1, 8'b11111111, K, Kout);
    mux2 #(8) m1 ({A[6:0], Kout}, {B[6:0], ~Kout}, sjplusone[1], Aplusone);
    mux2 #(8) m2 ({B[6:0], Kout}, {A[6:0], ~Kout}, ~sjplusone[1], Bplusone);
    mux2 #(12) Fmux ({2'b11, F1},   {2'b00, F2}, sjplusone[1], F);


texts: Implementing Multichannel ADC conversion and transfer data to PC

texts:
I have developed a system using the TI MSP430 G2553 that accomplishes analog to digital conversion of multiple sensors simultaneously.

So here is the question:

Can someone suggest me how to transfer the digital output of the ADC to the PC and store it in say, a text file?

EDIT: I am making use of CCS as my IDE for programming the microcontroller. Is there something inherent in CCS which will help me accomplish the task?


texts: Seeking deeper understand of reading a schematic with an op-amp IC (AD-8574)

texts:
A couple days ago I was seeking some education on reading a schematic, I had great answers for replies and I feel like I am closer. What I am trying to get my head around is the use of a dual channel op-amp circuit. I think the circuit shown below is indicating the exact part number I need to use, as well as the pins I would use from the IC itself.

Source: Schematic was copied from page 4 of the manufacturer's product datasheet.
Zhengzhou Winsen Electronics Technology Co.,Ltd
Looking at the part number's datasheet (the source of the below pin out diagram as taken from Mouser.com) it looks like I would just need one of these chips on the board, is that correct?

Is that IC in the pinout a quad channel operational amplifier? And last question, in the schematic above, is the schematic indicating the actual pin numbers to run the traces to? Seems like a clearly defined blueprint of what exactly I should be doing or am I just being overly optimistic?


texts: Synchronizing a diesel generator with a pure sine wave inverter

texts:
As the title reads, I'm trying to understand the best (Practical) way to synchronize a diesel generator with a pure sine wave inverter, in order to implement an automatic synchronizer based on microcontrollers.

I've searched alot for references, books and articles related to this topic and I came up (theoretically) with these conclusions :

To Synchronize any two sources of single phase AC power, these conditions must be achieved:

Phase angle between the two wave forms must match.
Voltage on both terminals of the sources must match.
Frequency between the two sources must match.

Now, frequency synchronization seems to be achieved since both the inverter and the generator is designed to output 50 Hz pure sine wave,
Phase angle condition can be achieved by studying the initial state of the inverter wave then start the inverter based on this method in order to make the phase difference between the two sources zero, for voltage It seems to be more complicated to match the voltage of both sources (since both sources are not designed by me /and seems to me that I can't control their voltage output/ neither the generator nor the pure sine wave inverter, I bought them both) so here lies the problem , how can this be done ?

Also I want to know (please) what's the effect of slightly different values in each condition of synchronization, and is my approach to this goal totally wrong ?

This is my first time doing something like this, but not the first time I deal with 220 volts AC, so any advice would be much appreciated.


texts: Is there a kind of switch that after being pressed, even if not released, will open the circuit again?

texts:
I want my sliding door to turn off the tv. So I opened the remote control of the TV, soldered a KW12-3 switch to the pads of the original ON/OFF momentary button, and everything is working good, I press the switch once and it turns off, and the same for turning the TV on. The problem is, when I tape my "creation" to the sliding door and the door is closed, my switch is always pressed, and the remote is constantly turning off and on the tv.

So I would need a switch which, after closing the circuit, even if not released, will open it again. Do I need a different kind of switch or I actually need to add other components such a capacitors and inductors? I'm sorry for my total ignorance about the subject, but I hope I explained the problem well.

The remote control and trigger switch I'm working on.

I actually bought the small universal remote and soldered the switch to it from the other side of the pcb. The tape is there just to blend with the color of the door, and to hold the red push button which is used to program the remote. The whole thing is about 4cm on the longest side, totally invisible if I tape it on top of the door, so I would be happy if it will work as I intend.


texts: Operate and speed control a 230V 50Hz AC Ceiling Fan with Power MOSFET based Dimmer Circuit

texts:
I am trying to control the speed of ceiling fan at my home using a power MOSFET based dimmer circuit.
The ceiling fan operates at 230V AC and can consume maximum 50 to 75 Watts power.
The circuit which I am using to control the speed of this fan is shown in below image. Some important highlights of the circuit are:

The Fan is connected between Load+ and Load- terminals
Live is 230V AC, IRF740A is Power MOSFET and PC817 is optical isolator
PWM control signal is provided at the input of optical isolator via a microcontroller

Here is what I observe when I try to operate the ceiling fan using above circuit:

When I increase the duty cycle of PWM, it successfully increases fan speed accordingly
When I decrease the PWM duty cycle slowly, fan still runs at same speed, and doesn't slow down
When I turn off the PWM, fan stops with a sudden jerk, and my MOSFET blows off after becoming too hot
The same circuit works well for dimming of resistive loads like incandescent bulb

So I wanted to know, what modifications do I need to make in my circuit, to safely handle the decrease in fan speed?
I want to make sure that after operating the fan at 100%, even if I turn off the PWM suddenly, the fan should still stop gradually and not with a jerk.


texts: Why does the MRI machine does not rip off its own electronic components

texts:
Maybe it's a lame question but it came up to my mind recently.
Usually, Electronic equipment or metallic materials are forbidden in MRI rooms. Also, there are no electric sockets present in that room. How is the machine designed so that it does not rip off itself!!


texts: Understanding CMOS Circuit Behaviour with Resistive Loads using Thevenin theorem

texts:
I have been reading the Digital Design: Principles and Practices 3rd Edition as a hobby. Unfortunately, I am stuck at page 103 of Section 3.5.2: Circuit Behavior with Resistive Loads.

In Figure 3-27: https://ibb.co/v1BVXrK, a resistive model of a CMOS inverter with a resistive load has been illustrated. (a) showing the actual load circuit and (b) using the Thevenin equivalent of the load.

To understand how Figure 3.27(a) is equivalent to Figure 3.27(b), I learned how the Thevenin theorem works. I watched a brilliant course about the theorem: https://www.youtube.com/watch?v=25axDabtoFk.

However, as far as I understand from the Thevenin theorem, we remove a circuit component and make it an open circuit. After the removal, we have only 2 open terminals. Whereas in Figure 3.27(a), by removing the components in the right-hand-side blue rectangle, we are making 3 open terminals, not 2.

So, how does the author convert Figure 3.27(a) to Figure 3.27(b) using the Thevenin theorem?


texts:
I have a level shifter (TXS0102DCT) connected according to the diagram below:

VCCA: 3.3v
VCCB: 5v
A2: trigger pin of µC
B2: output
A1: NC
B2: NC

The crazy thing is if I input 3.3V on the A2 pin I get 2.7V on B2 instead of 5V and I can't figure out why.
I also tried removing the ESD diodes D8,D5 and pull A1 to GND yet no result.
Can someone explain to me why it doesn't work like this?


texts: Why does an diff-amp being fed by two separate op-amps with low input resistances distort the signal on the inverting input?

texts:
I'm using the following circuit. In1 and In2 come from two separate amplifiers (Max9643), both of which are fed by a square pulse but have their inverting and non-inverting terminals criss-crossed with each other. The first stage amplifiers work well separately. Now coming to the second stage (i.e. the circuit shown below).

simulate this circuit – Schematic created using CircuitLab

When I use R1=R2=20k and R3=R4=100k, they work properly and In1 and In2 are shown below:

(This's only a spice simulation and practical output varies, especially with respect to limiting high frequency).

Now if I use R1=R2=20 and R3=R4=100, Vin2 somehow gets affected.

I realize I'm doing something wrong with the resistor values but what exactly is happening? On a practical circuit, more than voltage reduction, the edges seem to become contaminated and are jagged. I am using an op-amp with 10s of uA bias currents so the high value resistors might not be suitable for me. But if it's an input current/voltage issue why does this occur only at the inverting terminal? I've been beating myself up over this since I think this must be a basic issue, but I'm not able to put my finger on the exact cause. I'm planning to check this with a fully differential amplifier IC instead of the op-amp but I would really like to know what I'm doing wrong.


texts: pc817 large emiter collector voltage drop in saturation

texts:
I'm experimenting with a very simple circuit with a PC817 optocoupler. I just want to turn on an LED with the optocoupler output, but the bright is really low in comparison to a direct drive of the LED.

Here's my circuit:

simulate this circuit – Schematic created using CircuitLab

The problem I'm experiencing is a large colector-emiter voltage drop (around 2.8V), when the datasheet states voltages below .5V for my setup.

Is there something wrong with my circuit?

Thanks


texts: VHDL Plus operator `+` and Downto syntax

texts:
Considering variable a and b as STD_LOGIC_VECTOR (31 DOWNTO 0) we have a + b as 33 bit result;

How can we get 32 bits out of this?

Does VHDL have something like (a+b)(31 downto 0) or we should store c:= a+b and then get c(31 downto 0)?


texts: single cycle implementation with single memory

texts:
I've read that implementing a single cycle cpu requires two memories one for data and one for instructions. Why is this?

Using a single memory with two read ports (see figure below) wouldn't it be possible to fetch the instruction and read the operand specified during the same cycle?

EDIT:

@supercat

Would something like this work ?