texts: Why does this simple VHDL pattern for a shift register not work as expected

texts:
At first glance you would expect the VHDL source code below to behave as a shift register. In that q, over time would be

"UUUU0", "UUU00", "UU000", "U0000", "00000", ....

but instead it is always U after five (or more) consecutive clock cycles.

Why is this?

This code is actually a much simplified version of a far more complicated simulation.  But it demonstrates the symptoms that I see.

It exhibits this interesting and unexpected result during simulation under both ModelSim and ActiveHDL, I have not tried other simulators and would (secondly to an explanation of the cause) like to know if others act in the same way.

To answer this question properly you must understand that:

I know this is not the best way of implementing a shift register
I know for RTL synthesis this should have a reset.
I know an array of std_logic is a std_logic_vector.
I know of the aggregation operator, &.

What I have also found:

If the assignment temp(0)<='0'; is moved inside the process, it works.
If the loop is unwrapped (see commented code), it works.

I will reiterate that this is a very simplified version of a much more complicated design (for a pipelined CPU), configured to purely show the unexpected simulation results.  The actual signal types are just a simplification. For this reason you must consider your answers with the code in the form as it is.

My guess is that the VHDL simulation engine's optimiser is mistakenly (or perhaps as per specification) not bothering to run the expressions inside the loop as no signals outside change,  though I can disprove this by placing the unwrapped loop in a loop.

So I expect that the answer to this question is more to do with the standards for VHDL simulation of inexplicit VHDL syntax and how VHDL simulation engines do their optimisations, rather than if given code example is the best way of doing something or not.

And now to the code I am simulating:

 library ieee;
 use ieee.std_logic_1164.all;

 entity test_simple is
    port (
        clk : in  std_logic;
        q   : out std_logic
    );
 end entity;

 architecture example of test_simple is
    type   t_temp is array(4 downto 0) of std_logic;
    signal temp : t_temp;
 begin

    temp(0) <= '0';

    p : process (clk)
    begin
        if rising_edge(clk) then
            for i in 1 to 4 loop
                    temp(i) <= temp(i - 1);
            end loop;

            --temp(1) <= temp(0);
            --temp(2) <= temp(1);
            --temp(3) <= temp(2);
            --temp(4) <= temp(3);
        end if;
    end process p;
    q <= temp(4);
 end architecture;

And the test bench:

library ieee;
use ieee.std_logic_1164.all;

entity Bench is
end entity;

architecture tb of bench is

component test_simple is
    port (
        clk : in  std_logic;
        q   : out std_logic
    );
end component;

signal clk:std_logic:='0';
signal q:std_logic;
signal rst:std_logic;

constant freq:real:=100.0e3;

begin
    clk<=not clk after 0.5 sec / freq;

    TB:process
    begin
        rst<='1';
        wait for 10 us;
        rst<='0';
        wait for 100 us;
        wait;
    end process;

     --Note: rst is not connected
    UUT:test_simple  port map (clk=>clk,q=>q) ;
end architecture;


texts: Issue with universal motor velocity control by microcontroller

texts:
I'm using the circuit in the picture with a BTB12 600BW snuberless triac to control an universal motor (picked from a old washing machine, 220 VAC, 50 Hz) controlled by an arduino nano in customized PCB I made. At the moment only in "open loop" control.

As zero crossing I'm using the circuit below, with the output on the emittor side and a 10KOhm pull-down resistor.

https://images.app.goo.gl/VrPu1aej51YPKi3s8

The problem started when I connected the motor and ran the program, as you can see (fixed voltage, 45 VAC):
https://youtu.be/5Q3df7z6ZT0

Setting a fixed or variable (ramp) voltage from arduino, the motor sometime, at a random time, "jump" at a higher velocity then return back to the imposed velocity. It seems that sometimes the triac remains close for some AC cycle before to come back to the normal behaviour, and so on.

The simple code I'm using is here:
https://drive.google.com/open?id=1d2r3AmiUaU0wRjiOclEF8eqn1y7RIoIr

Note that the main loop has been purified from Serial and delay() functions to not affect the correct interrupt execution, but the problem is still present.

I passed the code to a friend of mine that have a very similar circuit (he only differ for mounting an R-C snubber on a classic not snuberless triac) and no problem of "jumping" appear to him.

At this point I'm thinking of a problem on the motor's collector. Unfortunately I don't have an oscilloscope. When the jump happen, I'm able to see a little increment in the output voltage (only the transient tail the multimeter is capable to capture).

What do you think about?

To Marko:
Yes, infact I was thinking that the R+C in my case should be used to snubber the optocoupler and not the triac (as suggested in many MOC30XX AN). For now I tried to insert a classic snubber R=100 Ohm and C=100nF on the main TRIAC side and it seems to work well. I solved temporarely but I didn't understand why a "snuberless TRIAC" requires in my case a snubber! Another test i can do is to eliminate the TRIAC snubber and insert an optocoupler snubber to see if the problem is solved the same. Maybe the current R+C I added helps in some way the turn off of the internal MOC triac, not the main triac. As last help, what size do you think I should consider in the R+C OPTO and R+C TRIAC. Currently I used 4W for the 100Ohm resistor (39Ohm in the AN) and 630V for the 100nF capacitor.


texts: SIM900a Modem IMEI 0, Help with TX RX pins

texts:
I have Simcom SIM900a GSM (SIM900a Mini DEV Board v3.9.2) and I am interfacing it with Arduino UNO.
I have no idea how to connect SIM900a to Arduino UNO.
What I did now is:

I connect the following Pin from above Image to:
5 to: GND (Digital GND near Pin 13)
6 to: 5V of Arduio
2 to: GND of Arduino near 5V
3 to: Digital Pin 0 of Arduino (RX)
4 to: Digital Pin 1 of Arduino (TX)
1 to: (No idea)
From Picture option 7, 8, 9 are not connected to anything.
Can you please guide me am I doing right?
I am getting hard time to find out what is TX and RX in my SIM900a module as it is not written there.
My SIM900a looks like this, this(Schematics given) and this.
When I upload sketch of:
Example > GSM > TestModem:
to Arduino, I got this output from Serial Monitor:

Starting modem test...ERROR, no modem answer.
Checking IMEI...Modem's IMEI: 0
Reseting Modem... Modem is functioning properly: IMEI: 0


texts: Using op-amp at high or low end of Vcc range

texts:
I'm looking to find an op-amp that can run off a +/-2.5V supply, sampling 60Hz AC voltage signals.
With all else being equal with operational amplifiers, is it better to use a component that has a maximum Vcc rating (ex: 5.5V max, 2.2V min), or min Vcc (ex: 4.5V min, 36V max) close to your supply voltage?
I'm asking because I'm torn between the TLV4197QPWRQ1 and OPA4325IPWR as both will work well for my application.
Mouser link to TLV4197QPWRQ1
Mouser link to OPA4325IPWR


texts: Designing split-phase grid-tie solar system

texts:
I'm in the process of designing and building a grid-tied solar power system, and had I'm having trouble finding a solar inverter that isn't MASSIVE (the smallest one I can find that meets my use cases and outputs split phase power is 6kw). The entire system will likely never go over 2kw~ of panels and 1.5-2kw inverter. I don't really want to just feed one side of the house -- I have whole-home power monitoring in place and because of the way this old place is wired, one of the split phases is typically 1kw+ more loaded than the other. I don't want to contribute to this or create a situation where if it's later corrected, my solar system now creates a large imbalance.
So I was wondering if it would be possible to use a large 1:1 isolation transformer with a centertap on one side -- feed 240v single phase into the transformer from a 240v inverter, then the center-tapped side to the L1, L2, and N for the house. Would something like this work? Is there a better way? Is if safe? I've seen a few 'autotransformers' around supposedly designed for this purpose, but I've had trouble confirming they can be used this way outside of marketing.
My questions are basically:
1). Can I use a big bare 1:1 wound transformer center tapped on one side to input 240 single phase and grid-tie to 240 split-phase on the other side? (Or even a 120v -> 240v centertapped with a single 120v inverter)
2). Would an actual 'autotransformer' like the ones made by Victron or Outback be better? Is it worth the $400~ more for the metal case they come in over buying a bare xfmr and wiring it myself?
3). Is there a better/safer way to accomplish what I'm trying to do? Or should I not care at all and just feed one of the split phases with a 120v grid-tie inverter?


texts: How do I operate any mercury vapor bulb and/or a metal halide without a ballast?

texts:
I have seen some youtube videos of some folks operating mercury vapor, metal halide and high pressure sodium bulbs on a incandecent bulb to limit current, but they never explain how.

I can't find anything about how this is done, what's the secret?
for clearity: secret = what wattage incandecent bulb with hid wattage?


texts:
I am trying to direct a bi-directional dc motor that is about 1.5v (i got it from a micro servo and it is about half the size of a 130 dc motor at 1.5 - 3v) with the smallest power source/battery possible. I'll be controlling it all from a micrcontroller.

I was told that MOSFET transistors would be the best thing for this project as it would draw the least amount of power and current for itself and the motors. Could someone tell me if this is the best solution or if there is a better way to establish an H-bridge at very low power? Any and all references, explanations, and links to tutorials would be much appreciated as I am still unclear if MOSFET is the combination of certain transistors to make the h-bridge or if the transistors themselves are considered MOSFETs...

I was using a L293d but that cost too much power and the batteries needed would have taken up too much space.


texts: Confusion with current in voltage-out amplifier

texts:
Why do we call some amplifiers this way? I mean lets say one call an amplifier as: "Current in voltage-out amplifier". I dont understand this because if current is in  then inevitably voltage is also in.

What makes us naming the type of input here(current or voltage)?

For example is common-emitter BJT NPN amplifier voltage in voltage out? But some current is also in and some current is also out. Why choose one?

What is an example of current in voltage out amplifier? And if current is in then some voltage also must be in why we call it current in?

EDIT: Please if possible give examples with single BJT transistor amplifiers. Because that creates my current confusion.


texts: Variable Gain Amplifier (VGA) Cadence Simulation

texts: I'm designing an Amplifier (VGA). I'm using Cadence CMOS 180nm technology. How can I find the power up time and power down time (1% of final current)?


texts: Best way to get exact proximity between devices

texts:
Need to get exact distance between devices like beacons or RF devices, exact means; about ~10cm tolerance.

Here is what I need;
I will use some devices like RF module or beacons on road and I need to make people with reciever walk on this road. The reciever that people have will communicate with these transmitter devices on the road. Transmistter and receiver has 0.5m to 3m distance and this distance will change while person was walking.

I made some search about BLE and RF and I saw getting distance by BLE is not reliable. [Source1]

In this link there are some calculations to find distance between RF devices, I can see result of even 1 cm distance change mathematically but can RF reciever take dB value decisively?

Most important part is here, this solution must be cheap and decisive, it should be feasible for indoor and outdoor, and shouldn't be more affected from noise and other factors

Lastly if RFID is suitable, can i communicate between transmitter on the floor with NFC on mobile phones from these distances.


texts: How do I incorporate output and input impedances connected to my circuit?

texts:
I'm designing a TTL to VGA DAC for a vintage PC, and I'm confused about the significance of the output and input impedances of my video card and monitor, respectively. The VGA spec states 75 ohms at both ends, if I understand it correctly. I couldn't find mention of an output impedance for the TTL video cards (I have an IBM CGA card and an IBM MDA card). My first inclination is to treat both the card and the monitor as 75 ohm equivalent resistors, and design accordingly. Specifically, my diagram would look like this:

simulate this circuit – Schematic created using CircuitLab
But on further consideration, it occurs to me that the video card is TTL, so there should be 5V on the signal lines, and I can just ignore its output impedance and treat it like a straight 0V/5V signal source. In that case, my diagram would be the same, except it would omit R1.
The contents of the solid box is just a resistor network, to combine the digital rgbi lines into an analog signal and drop the voltage down from 5V to .7V max, as per the VGA spec. No active components, transistors, diodes or other fancy stuff.
Am I thinking about this correctly, or am I going to set fire to something?


texts: Connecting and soldering audio cable of several earbuds, but none is working

texts:
I have about 10 sets of earbuds accumulated over the years, where just one of the two is working or the jack is broken, so I thought to try to fix them.

I've tried mixing several of them, in example cutting the jack from a set with only one earbud working, and connecting it to a set with 2 earbuds working but no jack; or adding a working earbud to a set with only one earbud working.

I didn't manage to recover any of them.

I've seen many tutorials on youtube and read many pages, and I don't think there is anything I'm doing wrong.

It should be as easy as stripping the insulation, separating the wires and removing the smaller insulation and then connecting them, making sure colors match.

I've tried stripping the thin-colored insulation either by fire (lighter), sand paper or with the soldering iron, but the result is still the same.

As a final trial, I cut the cable of a working earbud, and then tried to connect it back, so that I was expecting it to go back to its working status, but it didn't.

I tried just by connecting manually the 2 ground wires and 2 signal (coloured wire) after removing the insulation, and it didn't work;

I tried wrapping and it didn't work;
I tried soldering and it didn't work.

How is that possible?

I can't understand where I'm failing.

All of the earbuds are cheap Chinese products, but I don't think it should make a difference


texts: Operational Transconductance Amplifier Input Configurations

texts: I recently purchased several OTAs (Lm13700) but have had quite a bit of trouble using them. Going through the TI datasheet and a Nuts & Volts tutorial it's occured to me that transconductance amps don't really function in the same manner as "normal" op amps. Excluding the obvious currrent output in place of a voltage output the input configurations for many of the example circuits I've seen don't seem to follow normal op amp rules. Most pointedly, while I understand that hysteresis isn't a problem thanks to controllable gain I don't understand why so many circuits feature resistors attached to both input pins. It would seem to me that to achieve differential voltage gain one simple had to apply a voltage to the non-inverting input (perhaps with a voltage divider) and tie the other to ground. However, I tried this on a breadboard without success and only one circuit I found actually suggested this. Would someone mind explaning why OTA amplifier circuits differ so radically from ordinary op amps?


texts:
I need to change fans of my beamer but I cant find a replacement because I dont know which connector they used.
Thought it would be an 3 Pin connector but it isnt.

The connector in the pictures is 5x5x2,5mm

Hope anyone can help me!


texts:
Before I ask my question, I would like to say that im not exactly from the EE field, so please be easy on me.
I would like to use a Solar Panel and Rechargable Batteries as input to raspberry pi zero w that needs 5v.
I came across the CN3722 charging controller with battery protection. it can handle 1 or more multi-cell lithium battery
So this is the circuit I thought about (high level):

These are my main questions:

What will happen when the batteries are charging? The load still getting current? im not sure if there is cut out between the CN3722 to the Pi (as the two pictures I uploaded). If the load is still getting current, how can I be sure it will no go over\under from what it needs and ruin the Pi?

The Pi needs 5 V. does the CN3722 output voltage is basically the batteries output 7.4 V? The resistor should take 2.4 V?

What does it mean that the CN3722 can handle 1 or more multi-cell lithium battery? Are those batteries connected in serial \ parallel \ combined. How does it know how they are connected?

I’m a bit confused and ill be happy for guidance.
Thanks a lot!
EDIT
in addition to question 1.
This situation of connecting the load to the battery, in parallel, can damage the load? i guess my question is divided to 3 questions. what will happen (current wise) to the load when:
1. the batteries are full
2. the batteries are half full
3. the batteries completely empty

how can I know\make sure, the Pi gets the current it needs and not more or less?
from my understanding, when the batteries are half full, the current (that the solar outputs on the exact moment) will divide somehow between the batteries and the load.


texts: subtract two AC voltages with instrumentation amps

texts:
I'm implementing the so-called "3 omega technique", where a thin metal line is excited with a sine current. The metal has a high TCR which causes a 3rd harmonic oscillation, and I need to measure the amplitude of this voltage using a lock-in amp. I use a Keithley 6221 current function generator, which has high harmonic noise above 5 kHz, which interferes with the measurement of the 3rd harmonic.

In the litterature, several people have used a circuit such as the one illustrated in fig 2.6, pg 47 of this document : http://repository.lib.ncsu.edu/ir/bitstream/1840.16/5418/1/etd.pdf

The metal line is placed in series with a variable resistor with a low TCR, which is adjusted to the same nominal resistance as the metal line. Therefore by subtracting the 2 voltages, this will remove the fundamental signal, and harmonics caused by noise from the function generator, and the only thing left should be the 3 omega oscillation from the metal line.

However, I haven't found any detailed description of the actual circuit, other than the basic diagram in the link above. The only extra detail given by the authors is that they use AD624 amps.

So my question is, how do I actually implement this circuit ?

The 3rd harmonic is measured versus excitation frequency, which can vary between 1 Hz and 30 kHz. However harmonic noise from the generator isn't a problem at low frequency.
The resistance of the metal line is typically 50 - 100 Ohm.

Thanks !

EDIT : my reputation is now high enough to post the diagram here directly


texts: How to calculate Ic for a very simple NPN transistor circuit

texts:
I built a very simple circuit with an NPN (2N3904) transistor.
Then, I swept Vce from 0 to 5V and plotted a Vce vs Ic graph (as shown in the picture).
I heard Ic = Is*e^(Vbe/VT), where VT=0.025V, and Is and Vbe are given in the picture
(I also attached other parameters for the transistor as well just in case).

I keep getting Ic=107.4mA using the equation above, but the circuit simulator tells me that Ic has to be around 43mA.

I made sure that Ic/Ib = 100 throughout the whole DC sweep which makes me believe that the transistor is in the active mode.

Do any of you know how to calculate Ic in this case?


texts: Why should I connect Vbat pin of stm32f37x to VDD when there is no battery?

texts: I'm using a STM32f373x and with no battery. The product specification on page 77 says it should be connected to VDD. I have made a test with Vbat pin left open and the micro is working. Why I should connect Vbat to VDD and why it may work if it's open?


texts: How do I find the equivalent resistance of a circuit with a node between each resistor?

texts:
I can't make out what's in series and what's in parallel in this circuit.

The solution I've thought of so far is to consider R1 in series with R4 and R2 in series with R5. Then, (R1+R4), R3 and (R2+R5) would be in parallel and their resultant resistance would be in parallel with R6. I'm not entirely certain this solution is correct though.

A nudge in the right direction would be appreciated.


texts: Issues with LTSpice Sallen-Key single-supply Simulation

texts:
I'm having trouble with simulating a Sallen-Key single-supply low pass filter using LTSpice.
After fiddling around with the circuit for an hour I'm hoping for some assistance in troubleshooting.

For a transient analysis I'm inputting a 1 Khz 1 V signal and apply a DC offset. The gain should be 1 at this frequency. But at the output of my filter I'm getting a very very small amplitude centered at the DC offset.

For an AC simulation I'm inputting a small-signal AC amplitude of 1V. Again, I see a very small gain, and this time it's shown to be across all frequencies.

Based on the circuit design, these results are not what I would expect. I think my error must be in how I am implementing it using LTSpice, which I'm not an expert in using. I'd appreciate any input on what I might be doing wrong.


texts:
In short I'm building a relay controller and want to limit the current going to specific relays.

My power source is 12V DC @ 20A.

For one relay I want to limit the current to 10A and another to 2.5A. I'd also like to have minimal voltage drop, say ± 0.5V, but if this is unreasonable I understand.

If anyone would please help me I would be grateful. To keep things simple, I'd only need to be shown how to do this once and can figure it out for the other relays.

Thank you.


texts: What can be the cause of an exceptionally large latency for the UART receive interrupt?

texts:
I receive data on the UART, using an 8-bit atmega, usually around 5 bytes connected, then a long pause. The total time for one byte (with start+stop bits, I don't use parity) is 160 us. However, the receive interrupt is triggered 60 to 100 us after the stop bit, and nearly half the time it does not trigger at all! (checked with scope)

There were some quite long interrupts, so I blamed them, but after disabling every interrupt besides the UART, the situation remains the same. The UART interrupts finishes in under 10 us (typically 7us) all the time. The signal strength is OK, it's 5V, just as the supply voltage.

First, after realizing that a lot of bytes were lost, I was thinking that the signal frequency was the cause, but I double checked it: the baud rate is perfect, the signal quality looks good, the baud rate error is close to zero. If that was the problem, I would get some lost interrupts (because some bits were lost) but the rest should happen at the proper time, shouldn't it? In my case the interrupt comes very late, if at all, and even when in comes, sometimes it contains rubbish. The signal on the pin is OK, I can read and evaluate it correctly on the scope.

I searched for the typical latency of the UART interrupt, but could not find anything. I strongly suspect that a wild variation between 60 and 100 us should not be normal.


texts: Relation between current, resistance and voltage according to Ohm's law, Joules law of heat and P=IV

texts:
According to P=IV, if P is constant with increase in I (current,) then voltage has to decrease and vice a versa - which means they become inversely proportional but according to Ohm's law they are directly proportional.  What role does resistance play?

According to Ohm's law V~I.
But R should also be directly proportional to current as with increase in current heat increases and with heat increase resistance increase.  As H=I^2RT
therefore, with increase in current the resistance increases but due to resistance increase current will decrease and therefore resistance shall also decrease.

Please clear the confusion between relation of formulas.


texts:
I want to get an idea of how to use a chip, code it and burn it.
So an and gate could be a good choice.

I've thought about using AT27C01024-70PU or AT89LP4052-20PU.

Got this burner in mind: https://www.batronix.com/shop/programmer/BX32P/index.html

I've already used Arduino for a bit.

Could this work?

Thanks in advance for tips and advisement.


texts:
(This is not a homework question.)

While reading "Digital Computer Electronics" by Albert P. Malvino, I found this circuit on page 121, figure 8-22(a). It claims to be an example of a discrete TTL tri-state buffer, but I believe it to be wrong.

Best I can tell, the output will always be either high or tristated: it will never be low. I also simulated it online, and the results agreed with this assessment. I googled for published errata, but found none.

Would people say this circuit was in error, or am I missing something crucial?


texts: UART communication not working without injecting voltage in pin headers

texts:
I have a bluetooth module (rn4020) talking via UART to a stm32f103c8t6 MCU in a custom PCB, I also have an OLED screen and  some pin headers for listening what either module receives (as seen in the right top of the schematic).

The thing is that without connecting a FTDI chip in the pin headers, communication between stm32 and RN4020 does not work, I know this because the OLED screen outputs a message whenever a message from the bluetooth is received by the microcontroller (which is the first event to happen) and the message is not being shown in the OLED screen. I am not connecting ground from the FTDI chip in the pin headers and the communication proceeds normally which leds me to believe 3.8 volts injection is the thing making UART communication work (in contrast with 3.3 volts communication  without connecting anything in pin headers).

I've also seen that boards that pretend to achieve a similar functionality like Arduino Uno have some resistors for switching the UC communicates, though I know this is not the case I am looking for and makes me believe the problem I have can be noise related


texts:
I want to use a 3.7v lithium-polymer battery to power a esp8266 wifi module in a mechatronic project. This module works with 3.3v and I'm not an electronic expert so I use modules to avoid mistakes and time saving.
Despite the fact that it looks like a pretty common problem, I can't find any module to buy. I don't know anything about circuit design but I can learn. So I'm looking for any cheap solution for this problem.

using this:

to power this:


texts: Create a beeper when a battery voltage goes down to specific number

texts:
I have a 6 X 2V (400Ah) batteries in the office and I use usual DC to AC inverter to run our computers. One problem that we have is there is no way to know how soon our batteries are going to die. I got usual volt meter, but I need to monitor that all the time.
What can I do to make a beep when a battery volts goes below 11.5? I think it is very simple thing but I don't know what it is called or how to make it.


texts: Must an SV inout port be only in the top module?

texts:
When an inout port is used for read and write simultaneously it is necessary to use the "?:" operator with the HiZ to assign the port.
inout   [7:0]some_port;
wire    [7:0]port_in;
reg     [7:0]port_out;
reg     is_output;
...
assign port_in  = some_port;
assign some_port= is_output ? 8'bz : port_out;

Suppose that the design contains several levels of modules and the bottom module has a number of ports. Some of these ports are used by middle level modules. The other ports are directly used as inout of the FPGA.
Must I to drag inout ports through all hierarchy of modules as a separated port_in / port_out / is_output and then assign it in the top level module to the inout port? Can I assign somehow an inout port in the bottom module and then forward this port through all levels to the top? If I can't, do the professional SV programmers uses some macros to do this action with minimum strings of code?


texts: Mitigate the effects of magnetic induction heating in a three phase AC system

texts: To mitigate the effects of magnetic induction heating in a three phase AC system, it is common practice to group the conductors and to keep them in the same raceway. Also, three phase power is generated with each phase is 120 degrees out of phase from the others. Since Three phase power is generated by a rotating assembly (generator), and each conductor has a rotating magnetic field which surrounds it along the length of the conductor, are the magnetic induction effects reduced by the action of combining the three rotating magnetic fields into a 360 degree rotating flux envelope when grouping the conductors?


texts:
I am looking for the best (closest) way to create a solid state version of a dual coil latching relay. Essentially, a circuit that has two inputs (on & off) that when pulsed will flip flop the state of a FET from on to off, but when the inputs hard disconnect the state remains in either on or off (power to the circuit remains).
The background is an experimental university rocket that has an electronics package. While it is on the pad, you want the electronics package off for safety and then you want to turn it on remotely (through a gpio pin output from a ground tether). If the launch is scrubbed you need to turn it off remotely. In many ways, a dual coil latching relay would be perfect (no "power on" the rocket required), but the magnetic latching would not reliably hold up to the G forces and physical stresses of launch/landing. The two inputs are only connected, while it is on the pad. Once the vehicle launches they become physically disconnected, so the circuit cannot be dependent on their state.
So, I am considering some type of flip flop circuit that switches a FET. The circuit would need to be powered up separately, but would have little drain and would present little risk to the fueling operating.
Any creative ideas on how to simplify this? I am more software than I am hardware and my EE skills are a bit rusty, but this should be a pretty simple circuit.  Thanks!!


texts: Below is a schematic for adjustable voltage of the LT1528. The documentation did not mention whether there should be a small valued capacitor on input, nor did it mention what approximate value the output capacitor should be. Does anyone have any recommendations?


texts: How to limit the output voltage of a TCXO?

texts:
I am using an SiT1552 MEMS TCXO providing 32.768 kHz. It will be sourcing two ICs: a microcontroller and a DA14580 Bluetooth Low Energy transceiver.

The ICs and TCXO are all powered by 3.3V. The TCXO output is the standard 10%-90% LVCMOS voltage swing. It can drive up to 100 pF. It is not AC-coupled.

The MCU is happy with this voltage swing. It wants ~50% duty cycle.

The BLE clock input, however, is internally AC-coupled and needs a 0.1 - 1.5V (pk-pk) voltage swing.

In an app note which requires registration to view, it suggests to use a series capacitor for attenuation:

I can do this with a larger cap so as to attenuate the signal even more. The TCXO can handle the extra load.

Here is the result.

Does it look sane?
Will the MCU remain happy?
Is there a better method?

.

simulate this circuit – Schematic created using CircuitLab


texts: What is the purpose of the capacitor and resistor in this op-amp circuit?

texts:
Here is the op-amp circuit, which is found in this datasheet on page 5:

I have boxed, in red, the part of the circuit that I am confused about. What is the point of having this? Thanks in advance.


texts: LM7805 Voltage Regulator stops working when input voltage increases

texts:
I have the following circuit:

simulate this circuit – Schematic created using CircuitLab

I designed the PCB, had it printed and now I am testing it.
When I power it up the following happens:

When V1 stays below 27.8V circa, everything works fine. The WeMos board powers up, its led flashes as expected. Output voltage of the 7805 is 5V stable.
When V1 passes the 27.8V, the output voltage of the 7805 drops to 1V circa, shutting down the board. The transistor base voltage oscillates around 0.7-0.8V, causing the relay to open/close very quickly.
If V1 goes below 27.8 volts again the board powers up again and the relay stops flickering.

I tried to remove the WeMos board and put a resistor instead (with Q1 base floating), and in this case everything works perfectly fine, the 7805 doesn't switch off.
I am not an expert in troubeshooting circuits, so I'm asking for help.
What could be the problem? How can I start troubleshooting? Could it be the 7805 oscillates?

Edit: I installed a small aluminium Heatsink on the 7805 (TO-220 package). I calculated a maximum current consumption of 70 mA (there are some leds and another IC using the 5V), for a total power dissipation of circa 2W


texts:
I'm involved in some reverse engineering of a device I need to interface with.  With what little I know, and being able to capture a single data transmission, I think I've narrowed down the encoding method.  I suspect it might be a custom or obscure method because I can't find anything that matches what appears to be happening here.

At first I thought it might be a form of Manchester/Bi-Phase encoding, but any examples I've seen show transitions both rising and falling.  I have only falling transitions, and transitions between bits can be rising or falling.

Here's how the bit stream begins:

I have to assume that there are either some start or stop bits (maybe both) because the number of data bits I expect doesn't match how many bit frames I see overall.  The difference is in the low single digits and number of expected bits is in the high double digits.  I don't think the number is relevant to this discussion.  I only mention this because it corroborates my framing of the bits.

Somewhere in the middle of the stream I snipped this section to show where I'm marking each bit frame and what's happening along the way (scale is same as above):

I've marked an arrow on each transition I believe to be the start of a bit frame.  I suspect that no transition mid-frame is one logic level and a falling transition is the other level.  Though I've marked up the image with 1's and 0's, it could just as easily be inverted.

Has anyone seen this type of serial encoding before?  Does it have a name?  How likely is it I'm making a mistake with my interpretation?

EDIT 1: I can probably figure this part out, but if you've successfully decoded something like this in software (low level firmware) I'm interested in hearing about your solution.

EDIT 2: The repeating bit pattern in the marked-up image is coincidental.  Below is another section of the bit stream to illustrate this more clearly.  I would post the entire thing, but for technical reasons I can't do that right now.


texts: Need help with a solution for current measuring

texts:
I need a solution for measuring current through a load. It is a 15W load at 230 VAC or 24 VDC. I found the TMCS1100A4 from TI (datasheet). It's very nice because it can measure both AC and DC easily and the input and output are isolated. The downside is the sensitivity at 400 mV/A is probably a bit to low, as it would result in an output of 26 mV (at 230V input).
Does anyone have some suggetions for other sensors or ways of measuring the current?
I do not need to know the exact current, the output of the sensor will go to some comparators to detect if there is a current and if the current is too high (to indicate a short circuit for example).


texts: Confusion regarding the design of Lithium Ion PCB

texts:
From this site and many others, it seems to be universally recommended that a lithium ion battery not be discharged lower than 3.0 volts.  Most actually recommend to stop discharging at around 3.3 volts as there is little usable energy beyond this.

However, every lithium ion PCB or BMS stops the discharging of a lithium battery or battery pack at a voltage of 2.7 or even as low as 2.4.

Here is an example:

http://www.batteryspace.com/PCB-for-3.7V-of-Li-Ion-Battery-2.0A-limit.aspx

In this protection circuit, it stops the discharge at 2.4 volts/cell.

The reasoning I am given for not over discharging the lithium ion batteries is that it will hasten their demise and increase the probability of catastrophic failure such as fire or explosion.

So why the low voltages on the protection circuits and are our lithium ion drills etc being allowed to go to this low a voltage?


texts: Mosfet is getting hot in switching circuit

texts:
I've built a NiMh battery charger (6-cell battery, 7.2v, 3000Mah) using DS2715.
Input is 12v.
Here is the schematic:

For Q1 I used IRF9540N
For Q3 I used IRLB8721PbF
L1 is a 47uF ferrite choke
R7 (current sense) is 0.1 Ohm

The diode is blinking and a current flowing to the battery is 0.75A which would indicate that the circuit is assembled correctly.

The problem is that Q1 is getting too hot (can't hold a finger on it for more than a second) even with a small heatsink.
I now it can handle up to 175C, but I thought that in a switching mode it shouldn't be hot.
I know that for linear mode it would need to dissipate (12v - 6v) * 0.75 = 4.5W of power, but in switching mode it shouldn't even need a heatsink.

Can someone help me understand what's going on here? Can I do something to make it cooler (apart from getting a bigger heatsink :))

Here is the datasheet for DS2715:
https://datasheets.maximintegrated.com/en/ds/DS2715.pdf

And here is the source of the schematic that I've used:
https://www.maximintegrated.com/en/app-notes/index.mvp/id/4180

Here is the layout of the thing:

Cheers!
Leonti

Update:
After using more appropriate mosfets overheating issue went away :)
IRLML2246TRPbF for Q1
FK3503010L for Q3

Accepted answer has the details


texts: How do I suppress this voltage spike/dip?

texts:
I have a system that's currently testing automotive brushed dc motors.  Occasionally, I'm getting interruptions in my data acquisition system that I believe is being caused by transients coming from some of the motors under test.  Below is a transient that I was able to capture (I'm getting positive spikes just as often too).  Could I get rid of this with a bypass capacitor?  If so, based on the graph below and the timing of this transient, how do I size the capacitor?  Is there another device, such as TVS, that would work better?

UPDATE:

I placed an 18V TVS diode directly across the motor under test, which is roughly 6 meter away from the test system.  The scope measurement below was taken at the test system.  How is this possible?  Shouldn't it be clamped at 18V in the positive direction, and around -0.6V in the negative?


texts: On multi master i2c bus how to determine which device is the master of the bus?

texts:
On a multimaster i2c bus, how to determine which device started the transfer?

update (from comments made below by the O.P.) :

I am trying to make sense of http://www.i2c-bus.org/serial-resistances-and-debugging/ where it says:

  it is possible to recognize which I2C device is currently active by analyzing the low level on the I2C lines

What does that mean?


texts: Wire shield when using connector for strain gauge sensor

texts:
I have made strain gauge sensor with 1 strain gauge. Thet gauge is in "bottom" part of Wheatstone brigde (one strain gauge terminal is signal, second is connected to ground).

I'm using Sommer CICADA SO-D14 200-0451 cable. It's shield drain wre is connected to GND in the same spot at PCB as strain gauge wire.

Right now I'm not using any connector, but I'd like to make sensor instalation easier.

Now it looks like that:

Dark green - PCB with yellow solder points
Grey - sensor - it's just a piece of aluminium with strain gauge bonded to it. Shield drain wire is not connected to it.
Red - one strain gauge terminal (signal)
Blue - second strain gauge terminal (GND)
Green - Shield drain wire.

As I'd like to use connector I found 2 options:
1. Use 2-pin connector, shield drain wire connected to gnd terminal of strain gauge at sensor side of connector, but on pcb side of connector it will be connected only to gnd at pcb. I'll use that connector close to pcb - then It will be similar situation to one which is right now.

Use of 3 pin connector with one pin just for shield drain wire.

Will 2nd way a lot better than 1?

Connecting shield drain wire to GND at sensor side of connector is not possible (only ground point is at pcb).

Maybe there are other options?


texts: How do RIM and SIM instructions of microprocessor 8085 work?

texts: RIM and SIM instruction are used for interrupts of Microprocessor 8085.


texts: Smallest possible resistance (highest current)

texts: I'm new to electronics and I've been familiarizing myself with some basic formulas, specifically Ohm's law. It seems to imply that if resistance is smaller than 1, let's say 0.00001 Ohm, then I can get 100000 A of current with just 1V of voltage. So is it actually possible (not in just theory) to achieve that kind of current by lowering the resistance, or there's some limitations to how low the resistance can be?


texts: Is it okay to use a power supply that provides slightly more voltage and amperage than what's rated?

texts:
To preface; I am aware that there are a lot of questions that are similar to mine.  But I am finding mixed signals as well as jargon I don't understand; and I was really just hoping somebody could give me a yes/no because I'm really paranoid about plugging it in based off of my reading

I have an LED sign that says that it takes "Class 2, 18VDC, 2A" from a wall adapter with "100-240VAC, 50-60HZ, 1.2A"

I lost the adapter, and it's surprisingly difficult to buy a new one that matches those specs.  I did find an old laptop power supply that has these ratings:

Input: 100-240VAC, 50-60HZ, 1.2A
Output:19V, 3.42A

There is a weird symbol between the 19V and the 3.42A, but I have no idea what it means.

Here is a picture of the sign:

And here is one of the laptop power supply:


texts: Draw power evenly from two 12v battery banks, 24v solar system

texts:
I am currently running a small 24v emergency power solar system. I have a 40a MPPT charge controller with (4) 12v flooded lead-acid batteries in a 2S-2P configuration. I have a need for both 24v and 12v power during outages.

The 24v is obviously easy, but am having a problem getting a decent 12v buck converter to suit my power needs that doesn't cost an arm and a leg.

I was wondering if it would be possible to design a circuit that would take (2) 12v inputs and seamlessly switch between them constantly balancing the voltage on the two 12v banks, all the while outputting an uninterrupted high current (30+ amps) 12v output.

I know it's a lot to ask, and I realize the parts might cost more than a pre-made buck converter but I figured it would be worth a shot and I might learn something!


texts: Efficient and quick charging and discharging of a 2.7V supercapacitor with a 4.2V Li-ion battery

texts:
I have a 2.7V 50F* capacitor and a 4.2V high-power Li-ion slave battery. Based on  an ideal circuit that only has the internal battery resistance of approximately 1 m \omega\$ , the RC time constant would be 5ms. However, since charging it above its nominal voltage gets messy, I want to lower the voltage discharged by the battery in a way that offers negligible resistance. How can I do this?

Thanks,

BH

*EDIT: 100F, not 50


texts: MT3608/SX1308/... boost converter shutdown current (module)

texts:
I have a few step-up converter modules such as

https://www.aliexpress.com/item/33049532652.html

supposedly based on the MT3608 IC:

https://www.olimex.com/Products/Breadboarding/BB-PWR-3608/resources/MT3608.pdf

There seem to be clones/identical ICs available, such as SX1308:

http://www.nmj.sumomo.ne.jp/suz-avr/PMIC/SX1308-Suosemi.pdf (datasheet virtually identical to the one above)

I am aiming for a battery operated (two alkaline cells, so 3..2 V input, 3.3 V output) circuit with an "off" current of around 1 µA. According to the datasheet, the EN pin set to 0 V (GND) should achieve exactly this - however, depending on input voltage and feedback resistor divider (= output voltage) setting, this varies between 0.1 to 0.2 mA, which corresponds to the quiescent current for the PFM mode of operation.

I'm testing at Vin=4.6V, Vout=10V, no load.
Input current is approx. 1 mA when EN at Vin.
With EN at 0V, Vout corresponds to Vin.

From that it seems the IC does go into shutdown, but simply fails to fulfill the specs?

Of course, the feedback voltage divider causes about 50uA at that input voltage, regardless of the IC's consumption, so it's probably not suitable anyway.


texts:
i am trying to get my head around p channel mosfets and bought some A03401 mosfets. As i understand the mosfet will not allow current to flow if Vgs == Vds and thats why the pull up resistor is there. I have not even attempted to connect a microcontroller yet because the led was on in this configuration. i read Vgs and Vds and they are both 0.6v and so i am not sure why the mosfet is allowing current to flow. any help would be much appreciated. thanks.
ps. appolgies for poor picture quality, camera is broken.


texts: How to calculate a correction factor for two sensors

texts:
Suppose one has two sensors placed in the same environment (thus should be reading the same environmental data). But not being perfect instruments, there is a discrepancy between the two sets of numbers.

Sensor 1   Sensor 2
1         1
2         1.9
3         2.7
2         2
2         1.9
3         3
2         1.8
1         1
2         2
3         2.8

How does one calculate a correction factor between these two sets of numbers. The hope being that this first set of data could be a calibration set. Then (knowing the sensors are off) one could then move the sensors to different environments and record a new set of data.

S1      S2
1   10
2   12
3   13
4   15
5   15
6   16
7   17
8   19
9   19
10  20

and then apply a correction factor (based on the initial calibration) to the new data to account for the discrepancy between instruments.


texts:
On the one hand, PCB layouts are considered copyrighted information, and copying them verbatim is a bad idea for legal reasons.

On the other hand, the PCB layout of an evaluation board is pretty much a reference design for how to Do It Right.

Are there any issues with copying the eval board as closely as possible?  I would assume that it's meant to be copied, as their primary goal is for you to keep buying their chips and not have problems with them, but I've never seen this specified anywhere and the datasheets and eval board manuals still have the standard "All Rights Reserved", etc.

  Reproduction of information in TI data
  books or data sheets is permissible
  only if reproduction is without
  alteration and is accompanied by all
  associated warranties, conditions,
  limitations, and notices. Reproduction
  of this information with alteration is
  an unfair and deceptive business
  practice. TI is not responsible or
  liable for such altered documentation.


texts: How to calculate a LED pixel's luminance?

texts:
if the maximum luminous intensity of a single LED pixel is 1.8 candelas, how to determine it's luminance? The LED pixel is an SMD 5050.

Luminance, L = candelas/surface area

Which surface area should I be using for the calculation? Is it the circular area of the SMD 5050 LED?

Please explain. Thank you.


texts: Via fences or pickets important parameters for design

texts:
What is more important for EMI shielding effectiveness with respect to guard traces and via fences, the width of the copper trace that circles around the area or the distance between the vias to ground that connects to the trace and the other ground planes? Are both equally important or is one important and the other not so much?

Any good web resources out there for this?

Some background threads:
the thick copper trace

What is the purpose of holes on edge of the PCB?

TYIA


texts:
Here's a question that I was asked with the answer keys.

From the problem I deduced the net load impedance for one of the elements in the delta configuration will turn out to be 172.767|_3.66194 Ohms. Assuming that the voltage and current will be in rms we can use the equation.
$$ \frac{V_l}{Z_p} = I_p $$

So given the phase voltage of 200V we can use this equation to solve for Ip

$$ \frac{(\sqrt{3}\angle{30^\circ})V_p}{Z_p} = \frac{\sqrt{3}*200\angle{30^\circ}V_{rms}}{172.767\angle{3.66194^\circ}} = 2.00507 \angle{26.3381^\circ}$$

This clearly doesn't match with the first answer but matches with the second. But why? I realized that the sqrt(3) factor is the corporate but  removing it would change our equation to...
$$  \frac{V_p}{Z_p} = I_p  $$
Why is the phase voltage equal to the line voltage? I thought phase voltage was defined to be

$$ V_l = \sqrt{3}V_p $$

Which contradicts the equation they used above.

My other question is, is the phase voltage defined to be something else if we don't connect a 3 phase voltage source to it?


texts:
I think this is the right area where to ask this question.
I´v got a cattle mechanical scale like this ones here. I have to weigh around 300 cow every month and with this mechanical scale the work becomes very time consuming.
I need to make my job faster and easier. But I live in Argentina where good technology is extremely overpriced.

Do any of you happen to know a way of modifying a mechanical scale and transforming it to electric without having to change the actual scales system?

I most sincerely apologies if this is not the right section, but you must understand that it is a very specific question.


texts:
I have a board that has a dual voltage isolated DC-DC converter on it.

The converter takes 0 an 5v in and gives -5,0,5 v out.

The 0v of the input is actual ground.

Most of the PCB uses the isolated voltages.

Should I use ground and 5V (input) as my planes?

Or should I use 0v (isolated) for the underside plane, and some other value for the top side plane?


texts:
I am trying to select a current sense amplifier for my design. My design parameters are :-

Vrail:- 9V to 21V
ILoad :- 20A(max)

When I look on digikey,

http://www.digikey.com/product-search/en/integrated-circuits-ics/linear-amplifiers-instrumentation-op-amps-buffer-amps/2556125

I am confused with 2 parameters:-

Gain bandwidth product
-3db Bandwidth

Can someone explain these parameters? What is their significance in selecting right sense amplifier?


texts: How do I print debug messages to gdb console with STM32 discovery board using GDB, OpenOCD and arm-none-eabi-gcc?

texts: I'm programming an STM32 Cortex M0 discovery board (32F0308DISCOVERY) using OpenOCD, arm-none-eabi-gcc, and gdb. I was wondering if there is any straightforward way to log debug messages over SWD. I've read about the semihosting option, but this seems to require pulling in newlib or other big libraries. (There's only 64k flash available.) Is there any more lightweight way to log text over SWD, or is using the UART the only practical option?


texts: Connecting a 120V/30A variac to a 240V circuit

texts:
I have a variac rated for a maximum output of 30A. The problem is it takes 120V on the input and all of my 120V circuits are 15A, as expected. I unfortunately cannot just add an additional 30A circuit since I live in an apartment.
I have a 240V circuit with a 30A double-pole breaker on it (2x 15A breakers connected together). This goes to a NEMA 6-30R outlet but that means there's no neutral for me to get 120V. Since I live in an apartment and this normally powers my A/C, I'd prefer to not rewire it to be a 120V circuit (the A/C unit already sucks enough as-is; I really don't want to see it struggle with 1/4 of the power it was designed for).
I was wondering if it would be possible to use another transformer to step the 240V down to 120V, and if this would properly split the 30A load across both 15A hot legs so as to avoid starting exciting electrical fires in my wall.
If this is possible, I'm having trouble finding a reasonably-priced transformer with the appropriate power rating (3600VA+, not accounting for any core/coil losses) to do this. I guess I'd be stuck winding my own if I go this route and don't want to spend a ton of cash?
The only other thing I could think of was to rectify the 240, step that down, and then pass that to an H-bridge inverter. No idea if that is workable though, or if the variac can even handle a non-sinusoidal input (I assume it can since it's just a transformer, but I didn't see anything in the product description explicitly stating such).
Any ideas or help are appreciated.


texts:
I am a physicist with a limited knowledge of electronic.  I usually study my problems extensively on Internet before asking for a help.  This means that here I will present both the questions and probable solutions and I would like you to confirm or correct what I wrote.

I would like to obtain a relatively cheap hobby signal generator up to cca. 10MHz.  I have two requirements:

It must give floating signal.
It must be possible to ground the output within the aperture and still get a signal with no DC component.

Ad 1: This condition can be fulfilled only if power and the signal generator are galvanically separated, which can be achieved by using a transformer.  Therefore any signal generator that is DC powered (or has external DC power source) is out of the question.

Ad 2: The reasonable way to fulfill this condition is that the signal generator uses transformer with two secondary windings, e.g. 12V-0V-12V.  When the common wire of secondary windings is grounded, it is possible to get true negative and positive voltages.

It seems that practically all cheap signal generators use DC power source (which automatically rules them out due to condition 1).  One notably exception is model FY3200S.  However, according to this video, signal generator FY3200 does not possess truly floated output (for 110V line voltage, 50V and 100 uA on the floating ground!).  Fortunately, the secondary stage requires -12V, 5V, and +12V inputs, which probably means it should be able to make signals without DC component (condition 2).

Author of the video suggests that the problem is that the device uses less appropriate switch mode power supply instead of better linear power supply and suggests replacing power supply.   [I suspect that the less convinient switch mode power supply is used in order that the device could be used on both 220V and 110V power lines.]  However, no information on the design of the linear power supply or the benefit of replacing power supply are provided.

Since linear power supply should not be to hard to make, it seems to me that the best option would indeed be to replace original power supply with something like that:

I could easily and cheaply produce something like that and also add a switch at the connection between the common wire of the secondary windings and the ground.  And using second stage from FY3200S (as well as its box) I would avoid dealing with much more complex electronics of function generating.

Does this seem to be a good idea?  Would this at least reduce stray currents if not completely eliminating them?  Is the power supply above appropriate for the application?


texts: How to assemble PCBs when SMT machine doesn't have enough feeders?

texts:
I just got access to an SMT machine in a DIY fablab. I have a board that has about 50 unique components that I wish to assemble and test drive this new machine. I intend to make 20 of these boards. How should I go about it?

Do I load the 15 of the 50 components and have them put on the 20 boards or cycle through the components and complete one board at a time? My boards are not panelized since I was planning on assembling them by hand so I think would either have to take the boards out or the components. Looking for any practical advice on this.


texts: how does negative differential resistance in a PCT work?

texts:
I understand that up until a point (Vforward), the differential resistance is positive. And then it turns negative, and as the voltage increases, the current decreases, as you can see in this IV curve for a PCT (Point-Contact Transistor):

One can see that up until the red shaded region that the object acts as a normal resistor, where more volts will get you more current. Simple thus far. Next, in the shaded region, one can see that as you apply more volts, less current passes through the device, which inclines me to believe that something must be working "against" the voltage, and that this is acting as a generator that opposes the voltage direction.

But what physical phenomena can explain this?

How does it work with respect to electric fields, currents, and material types for a Point contact transistor?


texts: Schematic for pulse generator by Terence Thomas

texts:
TL;DR
Does anyone have the schematic for pulse generator by Terence Thomas, as described in Chapter 2 of his book Sound Synthesis (ISBN 9780830692767))?

I am trying to build the sequencer, on page 58 from chapter 6 of the same book, the schematic of which I found here on this post, of the thread, simple 8 step sequecer for SL (the mis-spelling/typo in the title is intentional).

The following page (page 60), describes the oscillator used to provide a clock signal to the sequencer:

The sequencer used together with the pulse generator (described in chapter 2) form a unique control facility

I have searched for over a week now, and whilst I have a general idea of the circuit, I am missing a few details1.
From a post, on Buchla 144 dual square wave oscillator DIY, it appears that the pulse generator referred to is a UJT relaxation oscillator:

This is a “Terrence Thomas” build, from his book, from years ago, that is very similar to a Buchla, but has a 2N2646 saw-relaxation oscillator and a TL071-schmitt trigger (square-wave), with a 2N2222, for pulse modulation. The book calls for a 741, which does not work for crap, with the poor slew-rate and overall bad performance. It is a really quirky oscillator.

So I now know that it is a UJT relaxation oscillator, most probably very similar to that which Terence Thomas has posted in Unusual Components and Applications
by Terence Thomas (Negisters, Unijunction transistors, Precision Resistors, and Hall Effect Devices):

However, some components (NOR gate, S2, S3, R5 and C7), which are referenced in Chapter 6, on page 60 are missing

Switch S3, on the pulse clock, provides access to the pulse output
when it is in the up position, but in the down position (as in the
pulse clock schematic), a single pulse mode engages. This mode of
operation allows the user to advance the sequencer just one stage. A
closer look at the pulse clock schematic shows that one section of the
quad NOR gate, combined with switch S2, resister R5 and capacitor C7,
form a bounceless switch. When switch S2 is pressed, the sequencer
advances one stage only, to facilitate easy tuning.

I could order the entire book from an online retailer, even though I only need one schematic from it, but it will take over a month to arrive, as I do not reside in the US. I have checked with my local area library/libraries, and second hand retailers, and they do not have the book available. There is not an e-book/PDF version of the book either.
Does anyone have a scan of the actual schematic, from chapter 2 of the book, or a re-created schematic in Eagle? Or even a complete schematic of the sequencer including the clock circuit, with the single step circuitry?
Yes, I could use any oscillator/clock circuit, but I would like to follow Thomas's original plan.

1 I found some addition information on these two posts (1 and 2), from Analog Sequencer. However, the schematic of the oscillator, although promised, was never posted.


texts: Power Supply amp doesn't match with adapter. Can I use the adapter?

texts:
Can I use this LCD display: http://www.itontec.com/product-detail/product-name-7/

With this adapter:

*Display Specs: Power Supply(5~12V 2A)

*Adapter Specs: Output: 12V - 1A

Is that safe to use this adapter with this display?


texts:
A sustained three-phase fault occurs in the power system shown in the figure (See Link). The current and voltage phasors during the fault (on a common reference), after the natural transients have died down, are also shown. Where is the fault located?

This question was asked in GATE Exam 2015, and I was unable to do it. I have no clue how to solve this problem. The question paper in which this question was asked can be Downloaded from here for verification of problem : gate.iisc.ernet.in/gate-answer-2015/EE_S05.pdf


texts: PLL with two input frequency within lock range for FM demodulation

texts:
I have current output from a photodiode which I believe containing at least two distinct frequencies that is not too far apart from the lock range of a PLL which taking this current as the input frequency.

I have seen this question, but it is not asking what I am asking.

The question what the PLL is expected to do with these situation (in theory).

Empirically, I observe that the output signal is switching between two states of the frequencies. I wonder if this is agreeable to the theory.

Note: possibly circuit may look like this

Update:
I found a close question asked here


texts: We have designed and tuned a prototype PCB antenna on a high-frequency, low-loss material.  We now have to move to a less expensive material for production.  Any guidance on length tuning of the antenna elements with this change in Dk?  My searches to date have been less than fruitful.


texts: Thermography difference between AC current wire and DC current wire?

texts: Is there thermographic difference between AC current flowing wire and DC current flowing wire? And thermogramic differences for drift velocities?


texts: I'm trying to use a 276-640 instead of a tsop 1236. I heard that it will still work. I can't find any datasheets for the 276-640. In the tsop 1236 datasheet, is the picture below. Does this apply to the 276-640 as well? I'm guessing that the 276-640 is newer and maybe better designed so that it doesn't need the capacitor and resistor shown in that picture.


texts: How does a relay or switch work with batteries or capacitors?

texts:
I am charging my capacitor so it can act as a battery for a short period of time. I already did the calculations for the battery discharging and charging.
My problem is now that I have a load, I want to prevent current to flow to the load until the capacitor is fully charged (or to my required voltage threshold) so I can get maximum output power/energy. When the capacitor is fully charged, the charge controller stops its current flow and stops charging.
What kind of switch or relay do I need that can read, detect or sense my capacitor is full and then connect the capacitor to the load until capacitor drops below a certain voltage?
My load is a wifi module which I don't want current to flow to it and cause problems before I get the correct power or energy levels that are needed.
My Capacitor will have a around 56 Joules of capacity.
My Load needs 1.65 Joules for 1 second, then only 0.1 Joules/sec
This will get me around 6-15 Seconds of discharging til I hit my minimum voltage of the capacitor which is 0.9V.
I want to prevent any energy to go to my load until the capacitor is full.


texts: Considerations for using various AC->DC adapters of different voltages

texts:
What considerations should I take in terms volts and current when using power supplies from different devices such cell phone chargers, hair blowers, etcetera; that I've cut of the tip and soldered two pins for easy connection to a breadboard.

I ask this because I just burnt an Op-Amp by polarizing it with two different manufacturer power supplies that provided 15v each.

Can I mix them in ways that circuit analysis says (e.g. parallel, series, series opposed)
What is the role of the specified current in the power supply, is it the max current or the current that it provides at all times when connected.
If two power supplies output the same voltage but their currents are distinct what would that indicate?

Thanks in advance


texts: Flyback converter design using the LM5021

texts:
I'm trying to design a 24V output flyback converter using the LM5021 (with rectifier and filters included). This 24V will be used in a buck converter to decrease to 0-12V 3A with one transformer or 6A with both transformers connected. I've managed to make this work using simulations but I'm not sure if the circuit shown below will work in practice:

I think my Pi filter after the rectifier might be too overkill? I've seen most designs use like one 100uF capacitor, but testing this on a resistor gave me a pretty big ripple
Vin stabilizer might use too many components, which increases BOM costs. It keeps it stable though.
A lot will probably be asking why I added a second transformer: The reason for this is cause I want to be able to increase the current by adding a module and I figured the transformer was probably gonna be the most costly (now still only a transformer with Schottky's). I'm kinda curious how much influence this has on the snubber circuit and output filter though?
Solar panel controller is not that important at the moment, but I'm trying to be able to either use a solar panel controller (24V output - Schottky diode voltage drop) or the flyback controllers (24V output). Since I'm not using them both at same time some voltage loss from diode doesn't matter for my application. I'm wondering I there's a circuit to automatically disconnect when the solar panel controller has voltage over it (was thinking just a MOSFET tbh)?

General question: Is there anything wrong about this circuit in the real world and will the double transformer configuration work? Also is there anything that is overdesigned and can be cut to reduce the costs?
Most of these components are not the ones I'm using on PCB (M1 will probably be a IPD70R600P7S*, transformer used will be the same 750343004 WE)
If anything I said above doesn't make sense or you need more information let me know! Thanks!


texts: How can I calculate the Cimon in a DC-DC converter?

texts:
I would like to use LT3649 IC, but I don't know how can I calculate the following in the datasheet: Output current monitoring and regulation section in page 10. The datasheet: LT3649
If I use 10k resistor for Rimon and 10nF capacitor for Cimon how can I calculate the value?


texts: Getting a neon light on the handset of an old GPO 700 series telephone to illuminate

texts:
I have been given an old handset for a 700 SRS rotary GPO telephone, with a neon light in the centre.
If it is connected across the ringer circuit, should it light up when the bell set is energised by the 90VAC, or is the voltage too low requiring additional equipment within the phone to raise the voltage?
I'm assuming that neon lights are not polarity sensitive either given that it is an AC device.


texts: What to do about two logic gates connected to the same wire?

texts: If I have two logic gates (made of mosfets) with outputs connected to the same wire or bus, I encounter an issue where, when the logic gates are at opposite logic levels they are both trying to drive the wire to their respective voltage. This creates a current and a unreliable voltage across the wire. As you can see in the photo below, there are two OR gates connected to one another. I want the shared wire to be at logic 1 but it is being held at logic low because of the other gate. Also there is a large amount of current between the two gates. How to people deal with this?


texts:
I have been reading through "Johnson, J. B.: Thermal Agitation of Electricity in Conductors" from 1928 and he keeps on talking about the "real resistance component" \$R(\omega)\$ of a resistor shunted with its own shunt capacity. I think these are questions of historical perception or change in usage of technical language:

For me a general impedance is defined as \$Z(\omega)=R+jX(w)\$, with \$R\$ not being depended on \$\omega\$. For an RC circuit this would be
$$
Z(\omega)=R+jX(w)=R+\frac{1}{j\omega C}.~~~~~~~~~~~~~~(1)
$$
So why should \$R\$ depended on \$\omega\$?
Nyquist talks about a "pure" resistance \$R_0\$. Is he talking about the purely resistive part of his RC circuit, namely \$R\$ in the schematic given below?

simulate this circuit – Schematic created using CircuitLab

How does he deduce eq. (2) in the paper:
$$
R(\omega)=\frac{R_0}{1+\omega^2C^2R_0^2}~~~~~~~~~~~~~~~~~~~~~~~~~~~~(2)
$$
If I talk about real part, I solely talk about \$R\$. If I talk noise, I usually go with the absolute-square. The absoulte yields
$$
\left|\frac{R\cdot\frac{1}{j\omega C}}{R+\frac{1}{j\omega C}}\right|=\frac{R}{\sqrt{1+\omega^2C^2R^2}}.~~~~~~~~~~~~~~~~(3)
$$
Squaring eq. (3) does not equal eq. (2). Where is my error?


texts:
I am currently playing around with a 74LS247 BCD to 7 segment decoder. The basic usage for decoding works perfectly fine.
But I would like to test out everything this IC has to offer including the blanking interval for controlling the brightness. According to the datasheet this is done via the BI/RBO pin. But I am confused regarding the way to use this pin.
As far as I understand this it serves as well as an output for cascading the zero blanking to the next segment and as an input for blanking this segment.
But how can I input a logic level into this pin without risking a short circuit? Will I get into problems when I connect it to H or L while it is outputting a different level?
In the datasheet there is a circuit that represents the way this input works, sadly I am not an expert in semiconductor magic to interpret it correctly.
The datasheet can be found here.


texts: P-MOS Gate-Source Threshold Voltage drop (Along with inrush current limiter)

texts:
I am having a circuit which I have tried to simulate and understand the working.

Circuit parameters :

Zener Breakdown voltage = 6.2V
P-MOSFET Vgs threshold voltage = 1.5V
Inrush current limiter = 3.3ohms

Below are my simulation efforts :

MOSFET Parameters :

ZENER Parameters :

Current Limiter Resistor :

There are other aluminium and electrolytic capacitors which are present. But for simple simulation circuit analysis I have ignored them.

My questions :

I have set the load current as 19.43mA using a 500Ohm Resistor.

I have a Zener diode whose Breakdown Voltage is 6.2V. So, as you can see the MOSFET Vgs Threshold Voltage is -1.5V. So, My question is, if the Vgs threshold voltage of the MOSFET is only 1.5V, the voltage drop between the MOSFET gate and source should only be 1.5V right? But from the simulation we can see that the voltage between the MOSFET gate and source is around 6.01V. Why is this?

From my understanding of BJTs, the voltage drop between the transistor base and emitter would always be around 0.6V-0.7V typically or whatever voltage they have mentioned in the transistor datasheet.

So, isn't the case similar to the MOSFET? Should the Voltage between the MOSFET gate and source be the maximum threshold Vgs voltage(if the voltage across it, exceed Maximum Vgs threshold).

So, I have used a 3.3Ohms current limiter resistor. I understand that Current limiting resistors are chosen to be a small value so that it does not dissipate high power during normal operating conditions.

But during the rise time of the power supply, how does a small value of resistor can help to reduce the high inrush current? Since, low resistance values do not offer much resistance to the current, right?
So, how does a small resistance can help to reduce considerable inrush current during the initial turn on condition?


texts:
I can't find any sources on how numbers are transferred during a phone call. I'm not talking about when dialing, but after the call is established. (like when you call an automatic bot and is given questions which you answers by typing numbers)

How are these numbers transferred? Are they transferred by some standard audio beep frequencies, or is it more complex than that?

I don't know if this is GSM specific at all, but I have an Arduino GSM shield, and I wonder if it is possible to capture these numbers in any way.


texts: Voltage of parallel components (RLC circuit)

texts:
Say we have the circuit above.
The 6 A current is applied at t=0.
I'm trying to get the voltage across the inductor to get di/dt.
If I run this circuit in LTspice, it will show a voltage of 30mv across all nodes. I'm not really sure how I get the 30mv. I was thinking that since the inductor would be a short circuit at t < 0, the voltage across it will be 0V, hence di/dt would also be 0. But I'm confused about LTspicee's 30mv result.


texts: Why won't my 12v 2.5A LCD driver board run when powered from a 12v 6A supply?

texts:
I recently put together a portable RetroPie project with an LCD from an old laptop, it runs fine off an old ps2 power supply drawing around 1A.

However, I decided to try running it off 8 LiPo cells (18650) I had lying around. I put the 8 cells in parallel, and connected them to a 6A DC to DC step up converter setting it to 12v.

The red LED on the driver board lit up telling me the board was receiving power, but when I hit the power button the LED turned green, which indicates that it is turning on, then backlight flickered and the whole thing reset, the LED also went back to red, this will repeat as many times as I push the power button.

I am assuming that the culprit is the CCFL needing more current than the DC to DC converter can provide, however the specs say that the board needs at most 2.5A so I am uncertain.

If anyone knows what I can do to get this working, any help would be greatly appreciated.

DC to DC converter: http://a.co/aEGWhaY
LCD Driver: http://a.co/b3kLdwH


texts: What is the cap for in Arduino reset circuit?

texts: My Arduino AtMega328P board has this circuit for reset. I understand the switch (LTSpice didn't have a switch symbol) pulls the line low, thats obvious, but what does the cap do when reset comes through DTR? Does it invert the signal or only allow a pulse?


texts: Transistor / mosfet for PWM dimming of 30W RGB LED

texts:
I am building a led mood light with a high power RGB LED (30W) using 3 constant power supplies for each color.

These are the items I had in mind (but open to suggestions):

30W Integrated RGB LED Light Bulb (10 Series and 3 in Parallel)
JR-30W 30W Waterproof LED Power Driver (AC 85~265V)

Each color will be controlled with PWM by arduino. So far so good, the problem is that the bc337 transistors I have can only go up to 800ma so I need something significantly beefier. What is my best and simplest option here? I'm not very knowledgeable in electronics so simplest solution would be best.


texts:
I came across the following solved question, but I have trouble understanding part of the solution. If anyone could shed some light into this I would be really grateful since this problem has been bugging me for a while.

We have the following power delay profile for a broadband bus:

relative delay (μs)   ||   mean relative Power (dB)
          0.0         ||         -1.0
          0.5         ||          0.0
          1.0         ||         -3.0
          1.5         ||         -6.0
          2.5         ||         -7.0
          4.5         ||        -11.0

There are a few questions such as: What's the mean excess delay (answer Tmean=0.79μs), RMS delay spread (answer Td=0.925μs) and the max excess delay, with Treff=-10dB (answer Tmax=2.5μs).

Up to this point I understand everything pretty well. But the final question is bugging me: "Can you tell that the bus is broadband, for a system that transmits with rate 25kbps and why?". The answer to this is:

The bus is narrow band, because Ts >> Td

I don't get it, at all. To begin with, how did he calculate Ts?


texts: How does the push button in this circuit work?

texts:
I am using a variation on the following Arduino project and it works, though I'm not quite sure how when it comes to the push button:

http://ardx.org/BBLS07/

The schematic (from p22 of http://oomlout.com/products/ARDX/ARDX-experimenters-guide-DD.pdf):

The 5V voltage source runs through a 10K resistor, which is connected to pin 2 and the push button.

I believe that the circuit works like so: when the button is not pushed, it is  a series circuit, and current only flows through the wire leading to pin 2. (Notably, the default state for digital pin 2 in the Arduino sketch is HIGH, not LOW.) When the button is depressed however, the circuit becomes parallel. Somehow, the circuit's action is constituted by this. Even if I'm essentially right I'm missing some details, so fill me in here.


texts: Why doesn't BD139 act as a switch like my 2N3904?

texts:
I got this low power transistor that I want to make a class-A amplifier out of, but I'm having a really hard time with it. It seems not to behave much like what I expect from a transistor.

The transistor came in a TO-126 package. I've never seen one like it, so I had no idea which side was the emitter. To figure this out, I tried to build a switching circuit.

Here's the test circuit I built:

When I unplug the base resistor going to the Vcc (+12 V), I expect Q1 to stop conducting. It doesn't though. I thought maybe I messed up the orientation. Flipping it around, however, did nothing. It does not matter how I wire it.

I replaced it with a 2N3904, and that worked just as I expected. The LED starts off not being lit. Then I hit the NO switch, and it lights up. But in the circuit above, it doesn't matter what I do, the circuit is always on.

What gives guys? Why can't I use this transistor as a switch?


texts: Achieving low-frequency clocks in FPGA fabric when below what PLL can provide

texts:
I have a 100 MHz reference clock source coming in from the XTAL on the board (Xilinx). As a trivial example, I wish to build a 1Hz virtual clock to drive a real-world clock/timer.
Now, as I see it, the Clocking Wizard is incapable of producing a frequency that low using PLL primitives or even if it were capable, the jitter and inaccuracy would be atrocious.
So that leaves me with a couple of options:

Use the Clocking Wizard to produce a clock which is ~an order of magnitude slower than the XTAL, then use a traditional counter divider to reach 1 Hz.

Directly use a traditional counter divider to reach 1 Hz.

My reasoning is that the first solution would help improve efficiency by minimising switching power losses, but both solutions don't feel particularly efficient to me.
Is there a way that I can achieve a very slow clock which is also not burning up millions of cycles just to count?


texts:
I am trying to put my controller in sleep mode and waking it up on a certain number of timer overflow. The code is as below:

//*******TIMER 2 INITILIZATION  will be used
    TCCR2=0X07;   //clock source select, prescaler
    TIMSK=0X40;  //timer 2 interrupt selected
    TCNT2=0X00;   // timer resistor
    sei();

    // controller sleep mode
    set_sleep_mode(SLEEP_MODE_PWR_SAVE); // sleep mode selected
    sleep_enable();  // set SE bit
    sleep_cpu(); // sleep mode activated
    do
    {
        if(count>=1000) //  min delay
        {
            sleep_disable();   // SE bit reset
            _delay_ms(1000);
            print("waking up.....");
            _delay_ms(2000);
            cmd(0xc0);
            print("AT+CFUN=1");
            _delay_ms(1000);
            transmit("AT+CFUN=1\r\n");
            _delay_ms(1000);
            _delay_ms(2000);count=0;
            break;

        }
        else
        {
            print("sleep");
            sleep_enable();
            sleep_cpu();
        }

    } while (1);

the corresponding ISR is as follows

ISR(TIMER2_OVF_vect)
{
    count++;

}

The problem it is not coming out of sleep mode.

I am using internal clock 8MHz and timer2.
edit: i found this description in datasheet ,so this means i have to use asynchronous clock for timer 2 (i.e provided by external crystal osc).Is there any way i can do this with the help of internal clock.


texts:
I just looked back at an old model for calculation ADC reading error.

When looking at it realised I have +/-0.5LSB for the worst case (WC) positive and negative channel. I can't really figure out why I added this when I also have a round function around it.

Wouldn't it just be enough to have a rounding? to the closest integer value?
I'm asking because I know I put a lot of time in making that model and I've hard time to believe I didn't had a thought about it.

The idea of the model is to round every value to an whole integer, to emulate what an ADC would approximately see in real life but in Spice.


texts: Current on each winding of a solenoid and wire selection

texts:
While I was reading an article about inductors and air core solenoids in general, I came across the term voltage per turn. Until then I thought that all of the windings of a coil are a continuous wire having the same current. But this term made me wonder that, does each turn of a coil behave like a parallel branch having the same voltage and current? Also if this is so, is the output current is equal to the sum of all the currents?

These questions are actually subsections of another main question that, if I have a  generator that generates a pulse of 800 amperes and about 10 kilovolts, then should I divide the current by the number of turns and look for wire qualification that satisfies the divided value?

Thanks in advance.


texts: Dissimilar Vector Group Transformers fed from 2 dissimilar phased sources of power

texts:
A bit of a debate among'st my peers about utilizing paralleling generators with dissimilar vector group transformers.
The theory goes as such: Generator A will be energizing the LV side of a Yd11 4160:600Vac transformer. Generator B will be energizing the LV side of a Yd1 4160:600Vac transformer. Both transformers have identical impedance % values. Both generators have sync scopes that match gen voltage to the bus voltage on 600Vac LV side before closing their respective breakers.
The common point of connection is on the HV side.
Generator A closes to dead-bus first energizing both transformer A and subsequently transformer B in a rather series orientation. Phase shift from LV to HV of transformer A will lead by 30 degrees which will energize Transformer B and subsequently be leading again by another 30 to the LV side. Generator B will now see a reference voltage 60 degrees leading of Generator A but it should not care: it'll sync to that voltage and close to the live bus.
The debate now is: will circulating-current (or cross-current) still be an issue, many of my peers say it will but refuse to explain and I cannot see how; as the difference in potential has now been neutralized by phase-shifting Generator B to match. thoughts?
Edited to eliminate vagueness: Both generators are identical in pitch windings (.6667 or 2/3rds), both have methods of KVAR sharing and both excitation systems are externally-powered PMG type and are tuned identically to produce exactly 600Vac L-L. Simply: is the vector group dissimilarity enough to produce circulating-current?


texts: Explanations regarding the blocking of diodes in single phase rectifier

texts:
I have started an analog circuits course and have trouble understanding the behavior of such opAmps and rectifiers.

This is the circuit given as example, however there's no extra explanations provided regarding the functioning of diodes and how the amp distributes the current.
LE: Does the opening/closing of diodes depends on the direction of current? Am i misunderstanding that the direction of current changes when Vi changes sign?
Thanks


texts: How do we separate source signals in spread spectrum?

texts:
In a point-to-point mode, that is, one transmitter and one receiver, I understand how a spread spectrum receiver can read the transmitted signal from a spread spectrum transmitter by knowing the code. But I cannot understand how different codes can be sufficient to separate signals from multiple transmitters on the same bandwidth.

When there are multiple transmitters transmitting at the same frequency and at the same time, even if they have different codes, don't their signals still interfere with each other? How come codes are not affected by interference?


texts:
I'm using a PWM IC to control some LEDs, and it uses an Open Drain setup. So I run 5V to the LED (through the appropriate resistor) then connect the LED ground to the PWM terminal.

I have one led that uses 100mA, which I believe is too much for the PWM IC. So I thought I would use a MOSFET, but I don't understand them enough to make this work.

The gate of the MOSFET is what the PWM IC would control to change the brightness, but the MOSFET requires a voltage to the Gate to close, and the PWM IC would only connect it to Gnd as an open drain.

I'm guessing I'm just wrong to use an N-type MOSFET for this setup, but I don't know what I should be using.

simulate this circuit – Schematic created using CircuitLab

The schematic doesn't show, but the PWM is open drain, so just a connection to gnd. The other LEDs being used are all drawing less than 40mA current, so they go directly to the PWM IC

Parts:
PWM IC - PCA9685
MOSFET - MMBF170L
LED - IR333-A

Thanks for helping a clueless hobbyist.
-Seth


texts: How can i convert a equation into a working circuit

texts:
How can i convert a Equation into working circuit
For Ex : Eb (Back EMF) = V - IR (Copper losses) of a motor.
How can i convert the above equation into a working circuit having variable & as well as non variable constants ??


texts: Why pic18fxxx microcontrollers is better for C language

texts: Pic18fxxx family has a lot advantages and improvements from the pic16fxxx family of microcontrollers. What is the particular feature that make them better for C programming than the pic16fxxx devices?


texts: Is analog signal arithmetic faster than digital one?

texts:
Would it be theoretically possible to speed up modern processors if one would use analog signal arithmetic (at the cost of accuracy and precision) instead of digital FPUs (CPU -> DAC -> analog FPU -> ADC -> CPU)?

Is analog signal division possible (as FPU multiplication often takes one CPU cycle anyway)?


texts: I'm interested in how diseqc motor works. I mean how satellite receiver communicates with it etc. Is there some literature explaining this? Which field of electronics is related to this? Maybe digital electronics?


texts: Overclocking an image sensor for higher FPS

texts:
What happens if I overclock an image sensor? For instance the OV7670 (datasheet) which has a rated maximum system clock input (XCLK) of 24 MHz and maximum pixel clock (PCLK) of again 24 MHz. The maximum standard frames per second is 30. Is it possible to completely "speed up" the sensor to get more FPS?

Will the overclocking affect the automatic image control functions like auto exposure control, gain control, white balance etc? Maybe resulting in the AEC running faster and producing darker images?


texts: Using OpAmps to amplify a low voltage/High noise DC signal

texts:
I am receiving a DC signal through a device called a Faraday cup. It is effectively a conductive piece of copper and when a gas is ionized nearby and the ions collide with the cup it is accepted as a current.

I want to do the following:

Convert this current into a voltage, the current is low so the resistance of the cup itself isn't quite enough to convert it all into voltage so I've included a resistor in the circuit as shown in the figure. The other end of the cup is tied to ground through a small bleed resistor as shown.
Take this low voltage input and amplify it, preferably 100 times.
Minimize noise and impedance issues whenever possible.

So to this end I was thinking of the following circuit.

simulate this circuit – Schematic created using CircuitLab

I will have a low pass filter set up as the input to the first opamp, the buffer, so I'm able to allow the lower (DC) current inputs into the op amp since that is what I desire. I want the resistor to be high enough to convert the current to voltage as I mentioned before, but capacitance can be changed to make the cutoff frequency decently low (So I can get as close to DC as possible).

On the other hand I'll have a high pass filter going to ground because I want all those high frequency noise and other stuff to be removed from my circuit.

Then the output of the buffer is fed into a non inverting amplifier with a gain of 10, then another with a gain of 10. The reason for this is because of bandwidth limitations on the LM358. So when all is said and done I want to have a decently high output voltage in the 1-3V range with as minimal noise as I can get.

Does this seem like a decent set up or are there ways for me to improve it? I had considered using an instrumentation amplifier but currently am not because:

I've haven't been able to get the gain to work, ie I'd simulate 100 gain but hooking that up I'd only be getting 20-40.
Single chip InstrAmp are a bit pricey
I just need to compare the faraday to ground so the two buffered inputs wouldn't benefit me as I'd just need to ground the inverting input.


texts: DS18B20 have the same 1-wire ids in proteus

texts:
I'm developing a temperature monitoring system and trying to model it in Proteus 8.1 SP1.
When I try to execute rom search for multiple DS18B20 it give back just 1 ID, but if I add one DS1822 I can see two Ids so I assumed that proteus has just a fixed ID for 1-wire devices.
Is it true?
Is there any workarounds of this problem?


texts:
I need to upload a code written for STM32F302RCT6 uC but I have stm32f4 type of uC board.
The code has the following dependency:
#include "stm32f3xx_hal.h"
#include "stm32f3xx_hal_conf.h"

I am kind of novice in ARM and all I need to upload the code successfully to proceed.
Would these libraries work for an stm32f4 device? Is it backwards supported?


texts:
I am having trouble getting my ADV7511 chip to display data in 1080p@30Hz. I am using data pins 23-12 for 12-bit data as defined in Table 26 for Style 2 (ADV7511 datasheet). I am following the timing diagram below from CEA-861-D exactly with a 75MHz pixel clock, which is slightly above the expected 74.25MHz clock.

I am able to generate 720p@60Hz from the ADV7511 using the same settings I am trying to use for 1080p@30Hz which the only difference being the frame size/blanking.

Edit
Forgot to ask the question...

Why would the ADV7511 fail to display 1080p@30Hz on an ASUS display, which an error message of "OUT OF RANGE"?


texts:
I generally tend to use vias close to the pin to connect my components to GND.
I was just wondering what is the right way to make connections when you have two components connecting to say 5V or GND. Should you connect them both on the same layer and use vias or one of the two?
For example, in the picture below (please ignore violation,) I have a component that needs to go to 5V. There is a 5V plane underneath all of this. Would you not connect them on the top layer and simply via it to the plane since that will be the shortest path, or would you have one connected to the plane and the other simply a net on the top layer - or does it not matter?


texts: Where can I look for USB 3.x superspeed mux chips for poor people that only have through-hole soldering tools?

texts:
I'm new to this realm of purchasing and I'm not exactly sure which of the different package names (SSOP, VQFN, etc.) are more friendly than others for basic through-hole soldering.

I would also be willing to use a SMT breakout board, but it seems most of the USB 3.x superspeed muxes I find come in strange dimensions that I can't find any breakouts for (or I don't realize they are in fact compatible).

Alternatively, a more USB-specific question -- is it absolutely necessary I use a mux "designed for USB 3.x" (per product branding) ? Or can I use traditional differential multiplexers? what attributes of these multiplexers make them better for USB 3.x SuperSpeed mux anyway?

Any info would be greatly appreciated.

Thanks


texts:
I seem to be having some problems with hooking up the L7805CV Regulator. When I provide it 12v @2A I seem to be getting an output value of 10.xxV???

What could I be doing incorrectly? Does it matter that the power supply is 2A and the Regulator is 1.5A?

Schematic: http://www.taydaelectronics.com/datasheets/A-179.pdf

(TOP VIEW)
--------|====== Output
|       |====== Ground
--------|====== Input

I have my photo below hooked up looking at it from the back.

What would I be doing incorrectly?


texts: Creating a unit to input an array of different computers display/sound and output only 1 with a switch to select

texts:
I have a few computers and I was wondering if there was an inexpensive way to link them all to a box that I would be able to use to select which ones I want outputted to my monitor(s).

I've only really had experience with an arduino, but is there some kind of microcontroller that I would be able to use to handle this?  It would be nice if I could hook up multiple monitors for it to work with (say I want to use two monitors while working on one of the computers).


texts: How to calculate typical signal trace clearance?

texts:
Knowing nothing more than most of the signal traces on a project are 7.5mil and it's a high end audio product, i.e. it's not a high frequency or any 'advanced' application, what would be a safe minimal trace clearance between parallel-running signal traces, assuming it's safe to run the traces under scrutiny in parallel.  I'm finishing up a PCB design project.  I plan to hand it in to my boss tomorrow.  He mentioned that the signal traces could have been set up with a 7.5mil clearance between them.  Right now I have it at 12mil, but I want to minimize it as I hear the extra 5mil of clearance will not improve performance of the product in any way and I would like to conserve copper (less pollution, creation cost, I could make the ground and power puddles larger, etc.)  I really need to learn EMFT!  I like to be able to calculate and model things mathematically when I design, however my level of knowledge is not at the level to where I could go through the design at the schematic level, decipher the relevant info from the datasheets and answer this question on my own.  Is there a PCB Design for Dummies? :)

Appreciate any advice.  Thanks.


texts: What is this connector type and how to connect to a loose wire

texts: I have a 3d printer heater cartridge that terminates with a rather odd connector.  The heater cartridge is 30W at 24V.  But I am wondering what kind of connector this is and how to connect a loose wire to it, can anyone identify?


texts: What gauge wire for 24V, 72W, 8m extension RGBW?

texts:
I have a simple question (I think) but I haven't been able to find the answer.

I have 4 * 5m lengths of RGBW LED lighting, which is rated at 24V, 14.4W/m. This is the maximum power draw, assuming the Red, Green, Blue and White LEDs are powered.

I have looked at the current / AWG table, and 22AWG, assuming rather pessimistically a 20core cable (I don't know what the core count is of the cable I could buy, so I'm erring on the side of caution here) is rated for 2.1A. I make that ~50W through one cable; given the highest draw for each LED strip would be 72W, this is around ~18W per channel, which is well below the 50W figure. What I don't know is what about the common (black) cable? Will that be needed to support the full 72W as it is shared between R,G,B and W?

In addition, would voltage drop be an issue over an 8m run of this cable?

I hope this makes sense - basically, if it's safe and won't cause problems, I would prefer to use 22AWG cable. However, would this be asking for trouble, and I'd be better off with 18AWG? (I want to avoid 18AWG if I can as it's far less readily available and significantly more expensive).

Thanks in advance. I hope that is enough information to help!

---EDIT---

The LED controller is: https://ltech-led.eu/en/d-series/1284-led-wand-controller-touch-d4-rgbw.html

It supports 4A per channel @24V for a total supply of up to 384W. I am intending to run four connections in parallel from the controller to the four strips (one run of cable per LED strip).
I am using a 24V, 400W PSU designed for LED lighting.

The LED strip is this: https://www.led-lighthouse.co.uk/led-strip-lights/rgbw-led-strip-controllers/12v-rgbw-led-strip-lights-60-led-metre-ip68-nano-tech

I have 4 * 5m runs.

The PSU is connected into the controller, and then the LED strips to the output on the controller.


texts: What's causing this power spike in STM32 low power mode

texts:
I'm using an STM32L073RZ on a bare board with just the CPU and decoupling caps. I'm powering the board straight from an Otii Arc and measuring current consumption. I'm running MbedOS 5.11.2.

When I call the sleep() function the CPU goes into a low power mode, with an occasional 5mA spike in current consumption approximately every second, see the image below:

What is the cause of this? I'm attempting to place the CPU into STOP mode with an RTC running - this should draw, according to the datasheet, 1µA current.

Further to this, how can I tell which low power mode the sleep() function has chosen? I'm trying to stay away from the HAL because I've had many issues configuring interrupts and the like.

For completeness, here's the code that's running on the board:

#include "mbed.h"

int main() {
    sleep();
}