texts: [Updated]How to select the values to move in assembler?

texts:
I'm trying to make the led blinks on the tm4c1294ncpdt, so the basic idea its to make 2 routines , one to select the GPIO port (in this case the F) and other to keep up on and off.

the setup routine is the next code

PIO_Init
    LDR R1,=0x400FE608
    LDR R0,[R1]
    ORR R0,R0,#0x20
    STR RO,[R1]

    LDR R1,=0x4005D400
    MOV R0,#0x
`   STR R0,[R1]

    LDR R1,=0x4005D51C
    MOV R0,#0x
`   STR R0,[R1]

    BX LR

SWITCH_ON
        LDR R1,=0x4005D000
        MOV R0,#0x
        STR R0,[R1]
        BX LR

The idea its to select the PORTF using the base address and the offset (0x400F.E000+0x608), store it in the R0 and later orr it  with 0x20 value.
Now these 0x20 is calculated this way, from the datasheet and the RCGCGPIO definition I'm using the F (6th) port so is this one

so this would be 0b 0010 0000 = 0x 20,

In the next part using the 0x4005D400/(GPIODIR) to configure the pin as output

this would be also the

0b 0010 0000 = 0x20

But this seems to do nothing and besides I remember to see in class that in similar GPIODIR configurations the number used was 0x02 (so I taked as a bad written number since I was using 0x20).

I don't know which one is right.

LDR R1,=0x4005D400
MOV R0,#0x20
STR R0,[R1]

or

LDR R1,=0x4005D400
MOV R0,#0x02
STR R0,[R1]

how must be calculated these values in the MOV instruction?

UPDATE
from the gpio.h in the SW-TM4C-2.1.4.178.exe, under the section "Values that can be passed to GPIOIntEnable() and GPIOIntDisable() functions"
// in the ui32IntFlags parameter.

I have found that

#define GPIO_INT_PIN_0          0x00000001
#define GPIO_INT_PIN_1          0x00000002
#define GPIO_INT_PIN_2          0x00000004
#define GPIO_INT_PIN_3          0x00000008
#define GPIO_INT_PIN_4          0x00000010
#define GPIO_INT_PIN_5          0x00000020
#define GPIO_INT_PIN_6          0x00000040
#define GPIO_INT_PIN_7          0x00000080
#define GPIO_INT_DMA            0x00000100

so the 0x00000002 is used and at the end the right version is

LDR R1,=0x4005D400
MOV R0,#0x02
STR R0,[R1]

As pointed by Ellio Anderson enabling the clock, selecting and using the port are different things.

And the right version of the code is

 PIO_Init
        LDR R1,=0x400FE608
        LDR R0,[R1]
        ORR R0,R0,#0x20
        STR RO,[R1]

        LDR R1,=0x4005D400
        MOV R0,#0x02
    `   STR R0,[R1]

        LDR R1,=0x4005D51C
        MOV R0,#0x02
    `   STR R0,[R1]

        BX LR

    SWITCH_ON
            LDR R1,=0x4005D000
            MOV R0,#0x02
            STR R0,[R1]
            BX LR


texts: Irfp250n n channel mosfet gate charge problem?

texts: I thought of changing and using a mosfet with n channels instead p channels. I connected the mosfet's source leg to the minus pole. I connected the drain leg of the mosfet to the plus pole. In this way, MOSFET will think that it is sending electricity to the minus pole and n Channel mosfet will work and connect positive + pole like P channel mosfets. I connected a lamp where the positive electricity was. The result is successful because it worked without any problems. But the arduino did not charge the mosfet gate leg. Later I saw that the plus pole of the mosfet was operating the gate leg when it is connected. Then I connected the plus pole of the mosfet to the minus pole of the arduino uno and the arduino uno started the mosfet smoothly. But I can do this with a maximum of 20 volts because the electric current coming to the gate leg is equal to the sum of 5.5 volts and 20 volts. When I use 100 volts, the electric current coming to the gate leg is 105 volts. Then the mosfet explodes. How can I solve this problem and run MOSFET with 100 volts. I can't charge mosfet gate leg any other voltage source. I can only charge their drain positive voltage source. I need to use n channel mosfet like p channel. How can I fix this charge problem ? Mosfet have only 20 volt Vgs limit capacity in gate leg. When I give it 105 volt it exploded like a bomb .


texts:
I am designing an automated telephone circuit that will work with the PSTN line. I already had a question to detect the incoming ring signal. Now I want to detect whether the opponent person in the line terminated the call. Because I need to cut off the line connection automatically since there will be no one to hang the handset on my telephone side.

So far, I learned that there is a constant beep sound which is generated by the telecom company when the opponent hangs his/her phone and terminates the call. The beep sound has ~2V peak-to-peak and a 5V offset, you can see the DC measurement and AC measurement below:

DC Measurement:

AC Measurement:

I am trying to detect the existence of this signal by an MCU. So far, I tried using an optocoupler but the voltage is not enough for driving an optocoupler. I tried the optocoupler circuit because the input (LINE- and LINE+) must be isolated from the output (GPIO of the MCU).

Are there any already-tested solutions for this kind of applications? Do they just use circuits for amplifying or filtering this signal to detect its existence? I wanted to use a comparator by using the Line for both supply and input but I couldn't get it work.


texts: How to use JTAG to test faulty soldered chips

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I have circuit using the ATSAM3X8E chip, soldering only the the chip and is complimentary passives. Upon connecting to it via usb to its native usb lines, windows throw an error saying that it cant get the device discriptor.

There could have many point in my circuit that could have gone wrong, bad soldering, bad cable, bad chip. So i would like to eliminate some. In my circuit i have a jtag breakouts, But i have no idea how to use them.

I bought a J-link mini edu for situations like this, even though knowing nothing about them. I downloaded their software but it would seem to be command line only. Does anyone know to Quickly test my chip using the J-link mini ?


texts:
Please give an intuitive explanation of difference between how a signal or data is carried using voltage and current?

I'm wondering even though current and voltage inevitability co-exist, why do we use the term for one concept(current or voltage)? If there is a signal out there somewhere, it is both current and voltage at the same time. But we name only one of its property.

We see in some circuits like heart rate signals or some other small signals which have to be in form of voltage in order to transfer the whole signal it to an amplifier (which has high input impedance). Even if it is voltage signal, we still have current passed to the amplifier.Why it is mentioned that voltage is transferred to input of the amplifier and why not current (when voltage causes current to pass)?


texts:
I have a very cheap, ebay 18650 li-ion battery. I was removing it from a battery holder, and as I was doing so, I noticed a bit of smoke.  I quickly got it out and took it outside.  It's winter. I set it down on some clear pavement, and brought it back inside now that it's cold.  I think it's safe now as far as thermal runaway is concerned.  What steps should I take from here?  The amount of smoke I saw was equivalent to putting a tiny bit of solder on a soldering iron.  How should I dispose of this?  YES: I am aware that cheap batteries have inherent risks.  OBVIOUSLY these aren't 9800mAh like they claim.

EDIT: I have to leave the house soon for an event, what can I do with it while I'm away?!


texts:
I have a small board that controls some appliances through the parallel port.

What i want to do is to put on high/low pin X with out modifying the rest of the pins (short story, control each pin individuality)

Example:
D0-D5 = 1
what i want D0 = 0 and  D1-D5 = 1

Thanks a lot.


texts: AA cell for low power embedded system -Debugging help needed

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I am using AA LI cells for an embedded system project.This is a low power embedded project with various modules consuming current in pulses.
Recently one of the prototype board stopped working. Although I measured the voltage across the AA measured 1.6V, it still does not work. How should I go debugging the problem and find the root cause. Can the AA cell be bad although it shows 1.6V?


texts: Strongest way to connect loose 20awg wires together

texts:
Hello I have 4 loose 20 awg wires leaving a stepper motor.  The loose wires are only about 4 inches long and I need at least 5 ft.  Therefore I will be connecting a longer section of wire to the loose wires hanging out of the stepper.  The wires are in a cable drag chain and are thus subject to constant bending which adds stress to the connection between the two sets of wire.
I have considered JST connectors, dupont connectors, spade connectors, soldering the connections...  But not sure the best way to go.


texts: General PSpice and 555 timer question regarding precision

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I have been experimenting with values recorded using a multimeter versus the voltages (RMS) simulated using capture. I simultaneously setup a circuit using a breadboard and drew exactly the same circuit in PSpice. I don't really have a particular circuit in mind. But I am sure I can set something up if it would help explain my problem.

Most of my component values have been extremely close to one another, such as resistors and capacitors. However I have hit a sour patch with the 555. It is not within a reasonable range. Not even close. The last test reported an error of about 45%. The breadboard pin 3 output voltage doubled the RMS PSpice voltage. Not good!

Is this normal? Is there anything that can be done to tighten up the PSpice component tolerances for ICs? I would like to use the program to its fullest, if it will let me!


texts: Confusion with grounding floating sources to be used with a differential ended data acquisition board

texts:
Regarding this paper, I first tried to wire single-ended floating sources to a diff ended data acquisition board.  But because of some power supply related issues and not wanting to make another interface for bias resistors I want to try another configuration by converting floating sources(0 10V DC outputting transducers like humidity, temperature ect) to grounded sources. So basically my sources are single-ended(not bipolar) and the DAQ board is diff ended.

To make it clear what I mean here are the general configurations from the paper:

In above table, I was using the the one on the top left with bias resistor and now I want to try the encircled one in red.

My questions are:

Here I made a more practical drawing:

As you see above the Figure 1 represents my current wiring scheme. And in that there is no earth ground involved. But still I'm having issues. And now I want to change this to "grounded sources to diff ended" scheme like the one encircled in red.

Regarding the red encircled configuration from the original paper:

1-) Can I do this floating to grounded scheme by using earth? Is my Figure 2 correct?

2-) No extra wire needed to be wired to AIGND?

3-) I wired the DC- to earth ground, but is this correct? I'm not sure whether DC- or SGND must be wired to earth ground. Because sometimes I observed wiring DC- to the earth reduces 50Hz interference.


texts:
I only have experience with low-speed boards that are 4 layers at most.
 I want to get into full-speed USB 2.0 and 100Mb/s ethernet, so I need some impedance controlled traces.  Instead of doing something professional first, I want to put together a hobby board that does these speeds.

Advanced circuits, the PCB house that I use, has this pdf about stackup thickness.  I've spent about an hour googling, but I haven't come up with clear reputable results to the following questions related to stackup thickness:

What is pre-preg?  What is its purpose in manufacturing?  I always thought that we just glued copper to an FR-4 sheet and then photoexposed it.
Why does pre-preg thickness change depending on how much of the pcb is filled up?
If I order an "impedance controlled" board, will the pre-preg thickness be better controlled?  How is this process different than "regular" boards?
Is there a textbook or nice, long app note that talks about all the nitty-gritty of pcb manufacture?


texts: Are waves inside conductor wires considered longitudinal waves, just like sound waves?

texts:
Are signals transmitted through electrical wires considered longitudinal waves (signals) or electromagnetic waves?

I think it would make sense for them to be longitudinal because the electrons are pushed then dragged back by the force of voltage or potential difference.


texts: What unit is expressing the effect of this capacitor in a common emitter amplifier?

texts:
I'm working through this handout I3.PDF in my attempt to understand negative feedback in amplifiers.  The following formula appears, in which the author is substituting \$v_{out}\$ and \$v_{in}\$ to arrive at the gain \$A_V\$ of a simple common emitter amplifier.  (I've pasted the excerpt below.)

It looks like \$Z_{CE}\$ is the capacitive reactance of the bypass capacitor.  My question is two-fold; first, is \$Z_{CE}\$ a  common variable to use for this (I thought capacitive reactance was \$X\$) and second, why does the author then convert it to some sort of a reciprocal unit \$1/s_{C{E}}\$ in the final equation?  Wouldn't it be easier to leave the effect of the capacitor in ohms?
Note: I usually would attribute my sources, but this handout has no author listed.  If anyone knows the author I'd appreciate being able to include his/her name here.


texts: Why symmetrical component analysis is necessary for fault calculation?

texts:
If a 3 phase fault occurs the direct axis sub-transient reactance is sufficient to calculate the fault current. But in case of an unbalanced fault it is not.

Taking the example of Line to Ground fault, where generator neutral is ground and a fault occurs on one of the terminals the circuit becomes,

Looking at the circuit it apparently looks fault current should be Ea/(Zs+Zn) but actually it is not. Can somebody please explain me why is it so?


texts: How does electricity produce heat, and where do the electrons go?

texts:
When electrons flow through a conductor it is subject to resistive loss, which has the unfortunate capability of producing heat from this current, leaving us with less current in the other end of the conductor opposite to the power source.

When current is lost due to heat, what happens to the electron? I mean, what is left of it? I guess heat is caused by friction, but that doesn't mean that the electron is not able to travel all the way through to the load of the conductor, or what?


texts: Altium designer, changing from imperic to metrics primitives won't work?

texts:
I'm using a trial on Altium, where for I guess support ignores me (Altium Designer version 19.0.14).

(I really hope it's better for real users if someone can confirm that, it would be most appreciated)

Back to the question: I want to change all the mils units to metrics.

I found this guide:

https://resources.altium.com/pcb-design-blog/menu-changes-and-switching-units-in-altium-designer-18

However, it doesn't seem to work. If I change the primitive to "MMs" I can't apply them unless I do some other changes as well, however, the settings won't apply anyway, it's still stuck with Mils.

Is Altium like this or can it be changed?


texts: Understanding Power Diodes and Heatsinks

texts:
I am working on reverse engineering and understanding a circuit board from the 1970s. I don't have a schematic diagram from the manufacturer. This board has an unmarked power diode that has a flange which is bolted to a large heatsink that is external to the casing. The diode casing is about 1/4" in diameter without the flange.
I've run a spice simulation on the circuit treating this diode as a standard diode and I get:

Max current = 3A
Forward voltage = 0.86V

So the power dissipation is 2.6W.
If I go to digikey and search for standard diodes that can handle 3A with a Vf of 1V I get the 1N5408RLG. This looks like a regular diode. Clearly no need for a heatsink.
https://www.onsemi.com/pdf/datasheet/1n5400-d.pdf
What am I missing? Is it just old technology vs new or do I have a misunderstanding?
Thanks!

(red is current, green is voltage)


texts:
I am having doubts in the relation between 7E1 and 8N1. Assuming I am transmitting a sent of characters between a client and a server; client sending with 7 bits and 1 even parity bit (7E1) and the server is to reply the same information switching to 8bits with no parity bit(8N1), how does the conversion happen. I have an example, but I cant seem to understand how the conversion happened. Here is the example
I am transmitting from the client :"06H 02H 05H 02H 0DH OAH"(7E1)
The server replies :"06H B2H 35H B2H 8DH 0AH"(8N1).

How was the server able to reply with such characters in 8N1 from 7E1 which it received.

Thanks.


texts: Best practices for production programming of data/NAND flash devices

texts:
A project has finally reached the point where prototypes are operational and ducks are lining up in rows for the first pre-production lot of boards. It uses a SOC device that boots its ARM core from an external NAND FLASH chip, which normally contains a boot loader, the embedded application, and other data resources. With a minimal boot loader and application in FLASH, it is easy to field upgrade. The prototypes got boot loaders installed with a JTAG cable, but that seems more than a little unwieldy for production lots larger than a dozen or so boards.

If this were a NOR FLASH or OTP PROM I would expect a vendor to be happy to take an Intel HEX or Motorola SRecord file and deliver devices that just work when soldered down.

Given the different nature of NAND FLASH devices, what issues should we be watching for?
What questions should we be asking vendors?
What form of image should we be expecting to be able to supply?

In short, what is the usual practice for pre-programming a NAND FLASH device before assembly?

Edit:

If it were to make a difference, it is an STM (numonyx or micron, why can't the chip companies stop selling each other their product lines mid design cycle?) NAND512xxx 512 Mb SLC family device that wants programming.


texts: Why would an electronic timer have a minimum load?

texts:
I need to replace an electronic timer lightswitch, and both the old one, and this example of a replacement, state that they have a minimum load of 40w.

Why would the switch have a minimum load, and what would happen if I used it with a lower wattage bulb?

This is a for a lantern style outdoor light (although the switch is indoor) and I'd ideally like to put a small energy saving led bulb (5-10 watts) in it.


texts: Help identifying the audio up/down switch in a Roku remote control

texts:
My sound down button isn't working in the Roku 3 remote control. I've opened it up to find that the rocker broke off. The Sound Up has B S marking and the Sound Down has G S. On the other side (metallic cover) of the switch, both the Sound Up and Down have B3B17A1
Anyone knows the manufacturer of these switches, or a compatible replacement?

enter code here


texts:
Container farms take a lot of light.  Powering it is not cheap.  And I have spent a lot of time pondering the different possibilities.
I've developed a PCB to control 4 x 300watt PWM amplifiers.  This gives me a simple controller that can handle sets of 4 channels of say 3 x 100watts COBs.  The inputs into these are ~24-27v and ~1500watts, so a single PSU at around $150 a pop will do it.
But that is not cheap.
I have some very grunty 5v controlled 20kw SCRs and 240v. If I rectify this with a FWBR and smooth it then divide in series by 12 light controllers, I get my ~27v to each fitting.
Was basically thinking to make a secure enclosure with 240v in and say 12 sets of terminals out. But how do I separate the terminals within the enclosure - i.e. types of resistor - and what happens if the load between terminals is very uneven (lights unused).
And is all this too silly, and not worth the $2000+ in savings for individual SMPS units.


texts: Very small scale electronic goods manufacturing regulations

texts:
I would like to make a 12v rechargeable battery operated robotic toy, for sale as a kit. This would be more of a hobby for me, selling say 5 units a month with a very small turnover. It would just involve a standard wall socket charger, a few 12v motors / servos, a microprocessor, a couple of li-ion batteries and an enclosure. I would probably have the pcb made professionally. I would offer the option to have it unsoldered or solder it myself, and I would make the enclosure pieces myself.

As far as the electronics and electrical circuity goes, what regulations, if any, would I have to be concerned about? It would not use any kind of radio link, and other than the motors, would not involve any kind of electrical circuits prone to EMI emission. I want to avoid buying any EMI detection tools given the expected tiny turnover. I am interested mainly in UK regulations, but any country's regulations would be helpful to give me an idea of what to expect.

(PS, any regulations regarding mechanical safety would be a bonus but not expected here!)

Thanks


texts: High voltage measurement with an Arduino

texts:
I'm looking for a way to somehow measure voltages in the range of 60~90V with an arduino analog input. These voltages are biasing a rather sensitive APD exposed to very low light levels, which supplies very small currents (~0.8 uA) for a transimpedance amplifier. The biasing circuit is shown below.

I though about using a voltage divider with the lower resistor having a bypass Zener to protect from over voltage, but that would require very large resistances (8~10 GOhms, and I'm mounting this on a PCB). What kind of interference could this have on the APD measurement?


texts:
I'm interested in designing a microphone array which will have 5+ inputs which need to be synced, possibly more. I want to sample each input at 20-30khz at 8-10 bit resolution.
I would prefer not have to have 5 separate ADC but the MEMS microphones I have seen which include ADC all use an odd protocol which I am not sure about.
Additionally even if the microphones all used SPI or I2C out I don't think I have seen any microcontroller which has 5+ inputs.
What would be the standard approach to this problem?


texts: How do I determine the unknowns for this equation?

texts:
Suppose a series RLC circuit in series with a 12 V battery and a switch initially opened. R = 100 Ω, L = 100mH and C = 10uF. L and C are initially discharged.

A t=0 the switch is closed.

I want to know the current equation.

I calculate \$ \alpha = \frac{R}{2L} = \frac{100}{2 \times 100x10^{-3}} = 500 \$

then \$ \omega_0 = \sqrt{\frac{1}{LC}} = = \sqrt{\frac{1}{100 \times 10^{-3} \times 10 \times 10^{-6}}} = 1000 \$

\$ \alpha < \omega_0 \$ , so we are dealing with an underdamped circuit and the current equation has the form

\$ i(t) = e^{- \alpha t} [K_1 \thinspace Cos(\omega_d t) + K_2\thinspace
Sen(\omega_d t)] + I_{\infty}\$

I need to determine \$ K_1 \$ and \$ K_2 \$

I apply the first initial conditions. Current at time 0 is 0

\$ i(t=0) = 0 = e^{0} [K_1 \thinspace Cos(0) + K_2\thinspace
Sen(0)] + 0\$

0 = [K_1 + 0] + 0 \$

\$ K_1 = 0\$

Second condition, \$ i'(0) = 0 \$

The derivate of the i equation gives me

\$ \frac{V_L}{L} = -\alpha e^{- \alpha t} [K_1 \thinspace Cos(\omega_d t) + K_2\thinspace Sen(\omega_d t)] - \omega_d e^{- \alpha t} \thinspace K_1 \thinspace
Sen(\omega_d t) + \omega_d e^{- \alpha t} \thinspace K_2\thinspace Cos(\omega_d t)
\$

when I apply t=0 that gives me
\$ K_2 = 0\$

With K1 and K2 equal to zero there is no current equation.

How do I get these unknowns?


texts: Altium Collision DRC error? Cant figure out why

texts:
i have finished my PCB design with Altium. I ran the DRC, to check if there are any errors. Strangely i got like hundreds of errors. First i couldn't find out why, but i managed to narrow it down to one footprint.
I have a footprint, i've designed it myself for a button which somehow throws multiple errors.
First there are errors like:

Clearance Constraint: (Collision < 0.089mm) Between Pad
SW6-1(9.381mm,102.69mm) on Multi-Layer And Pad
SW6-3(7.381mm,100.936mm) on Multi-Layer

this would say the two pads on the footprint are colliding. But as you can see in the Picture they aren't. I've measured about 0.5mm between them.
But the error which is even more interesting is the following one:

Clearance Constraint: (0.01mm < 0.5mm) Between Pad
SW2-0(9.413mm,288.69mm) on Multi-Layer And Polygon Region (186
hole(s)) Int1 (GND)

It says the clearance between the Polygon and the Pad is to small. I've measured the clearance and it is exactly 5mm. But somehow the DRC thinks it isn't. One interesting thing i noted is the  two arrows wich show where the clearance is smaller than 0.5mm (Red circle in image). They measure not from the Polygon to the pad, they measure from the polygon to somewhere between the pad, which is evidently shorter than 5mm.

My only explanation is that the DRC thinks the Pad is bigger than it actually is.
Im really lost, i tried to edit the footprint, to edit the rules, nothing worked. It might be a small fault, but i really want to figure it out.
Does anyone have an idea why this error is caused?
EDIT: i asked Altium, they didn't figure it out... i just ordered the PCB with the errors. The Gerber seems to be fine.


texts:
Is there way to calculate slew rate of following circuit?

simulate this circuit – Schematic created using CircuitLab

Datasheet for Transistor

Datasheet for Diode

I chose the PMOS and Diode arbitrarily from what I could choose from Circuit Lab.

If VTRIG goes from 5V to 0V, how can I calculate the slew rate (V/us)?


texts: How does the power usage and voltage of a universal motor change when running on DC?

texts:
I have a 2400w universal motor from an AC powered garden blower (230V @50Hz here in Australia) and am wondering what voltage and power requirements it would require from a DC source to give roughly the same amount of mechanical power and speed?

Also the armature brushes and the field winding's are wired in parallel series, could I gain some additional efficiency out of the motor by powering them from different voltage/current sources?

Reason I'm asking is that these motors are mass produced ridiculously cheap (the entire blower is only $35 at Bunnings - a tool store chain here in Australia) whereas any other motors of a similar power rating I have found are usually at least a factor of 10 more expensive and I plan on using multiple motors in my project but will be running from batteries so would like to know if there is room for optimising on the cheap.


texts: Verilog always block w/o posedge or negedge

texts:
I have a basic Verilog block that I wrote to trigger on any change in the signal.

always @ (trigger)
begin
  data_out <= data_in;
end

I expected this to trigger on the rising or falling edge of the trigger.  Instead, it tied data_out to data_in.  Even when the trigger was in steady state, the output was changing with the input.  What am I missing here?

EDIT: I can only use the three signals listed: data_in, data_out, and trigger.  The output must initiate on the bit flip of trigger.


texts: Current through a diode changes for the same forward voltage in two circuits

texts:
In LTspice IV, I am simulating a 1N914 diode behavior in response to a variable current source in two circuits. One circuit has just the current source and the diode, and the other has the current source and a the diode connected in parallel with a 1 kilo Ohms resistor. I vary the current out of the current source from 0 mA to 2 mA, plotting the forward voltage across the diode on the left and the current through it on the right, both on the vertical axis, versus the current out of the current source on the horizontal axis.

As shown in the picture, when I put the horizontal cursor line at the voltage where the forward voltage (V(D1)) is almost 540 mV, different values of current through the diode appear in each circuit ( I(D1) ).
Shockley equation tells that if the forward voltage is constant, then the forward current must still the same.


texts: Can bike/motor brake (and/or) gear shift cables used as a conductor

texts:
I am a mtb rider and my bike has green/black theme going on. There are not many green (especially neon) sleved cables around. (Nor the heat shrinks' green match the bikes'). I do not want to interfere with the theme.
Based on that, I have 3 questions as follows;
The neon green on brake cables look so great that I want to use a new pair of them to power led's in the front. Would the metal's conductivity/resistance affect the power and generate an excessive power loss? Would the cable heat?
I do have a multimeter and I could measure the static resistance, Find the voltage and amp requirements of the lamp and assume the cable as a big resistor as shown:

simulate this circuit – Schematic created using CircuitLab
Would I need anything else to consider before hopping on to the project?


texts:
For days I work on this and I have no solution. My ACMD 41 constantly returns 0x01. Here's my code. Can someone help me with this, I really need someone who worked on this.

char micro_SD_Init()
{
    //raise CS and MOSI for 80 clock cycles
    //SendByte(0xff) 10 times with CS high
    int i;

__delay_cycles(500);

// Init SPI Module
SPI_init();

/* Enable CS bit for using */
P3DIR |= BIT0;

//initialization sequence on PowerUp -> 80 clock cycles delay
CS_HIGH();
for(i = 0; i < 10; i++)
{
    SPI_Send_Byte(DUMMY_CHAR);
}
CS_LOW();

SPI_Send_Byte(DUMMY_CHAR);
SPI_Send_Byte(DUMMY_CHAR);
//Send Command 0 to put microSD in SPI mode
micro_SD_SendCmd(MICROSD_GO_IDLE_STATE,0x00000000,0x95);
while (resp1 != 0x01) // resp1 != 0x01
{
    SPI_Send_Byte(DUMMY_CHAR);
    micro_SD_SendCmd(MICROSD_GO_IDLE_STATE,0x00000000,0x95);                 // CMD0
    resp1 = micro_SD_GetResponse();
    SPI_Send_Byte(DUMMY_CHAR);
}

SPI_Send_Byte(DUMMY_CHAR);
/* Send if cond */
while ((array_resp[0] != 0x01) && (array_resp[3] != 0x01) && (array_resp[4] != 0xAA))
{
    micro_SD_SendCmd(MICROSD_SEND_IF_COND,0x000001AA,0x87);              // CMD8
    micro_SD_GetLongerResponse();
    SPI_Send_Byte(DUMMY_CHAR);
}

/* prosla CMD8 */
CS_HIGH();
SPI_Send_Byte(DUMMY_CHAR);
CS_LOW();

/* Tell that the next command is aplication-specific command */
do
{
    SPI_Send_Byte(DUMMY_CHAR);
    micro_SD_SendCmd(MICROSD_NEXT_ACMD,0x00000000,0x65);           // CMD 55

    CS_HIGH();
    __delay_cycles(50);
    CS_LOW();
    SPI_Send_Byte(DUMMY_CHAR);

    //ACMD41
    micro_SD_SendCmd(MICROSD_SEND_OP_COND,0x40000000,0x77);
    resp1 = micro_SD_GetResponse();
    if (resp1 == 0x00) break;

} while (resp1 != 0x00);

//SPI_speed_up();
//--------------------------------------------------

while (SPI_Send_Byte(DUMMY_CHAR) != 0xFF)
{
    SPI_Send_Byte(DUMMY_CHAR);
}

// da provjerimo napon napajanja na kartici
SPI_Send_Byte(DUMMY_CHAR);
micro_SD_SendCmd(MICROSD_READ_OCR,0x00000000,0x75);
micro_SD_GetLongerResponse();

if ((array_resp[1] == 0xC0) || (array_resp[1] == 0x40))
    printf ("SDHC kartica validna!");
else
    micro_SD_SetBlockLength(512);

return (MICROSD_SUCCESS);

}


texts: Charging a single 12V battery from 2 solar panels

texts: I'm building a solar powered robot that uses a 12V lithium battery. It will have two (17.6V max) solar panels - one on the top and one on the bottom (so it will still work if it flips), meaning I won't be able to wire the two panels directly together (as the one on the bottom would limit the one on the top), and I read that wiring controllers together isn't a good idea either. How would I best supply 1A at 12V to my robot?


texts: How does an optimized car battery charging system could be designed?

texts:
To start, I saw a scooter electrics. In that implementation, after quite a weak (in my sense) generator it has some shunt linear regulator, that just dissipates overvoltage to heat. Oh god! Weak generator + such many losses + inability to carry electronics, I would never buy myself one! :)

Now consider I've bought some big car, and I am electricity geek, so I've somehow managed to install 480Ah*12V battery pack in it. I want to be able to run kind of welding, and have many electrical devices, but power consumers are not the case. Just appreciate it's somehow could be used, in a quite short time.

I feel that I should modify supply system in a first place. First step is ofc is buying a powerful generator, I'll accelerate slower, and would agree to waste some amount of engine power to charging, at its best! I heard car generators are 3-phase. Scooter weak stuff is 1-phase. But what's after? Generator is working at a quite random RPM, its rectified and voltage varies alot. What should I place after a generator between battery? Or how to design extremely-heavy load car charging system?

PS. Indeed a PC exists in that car. It could control and have to log voltage and current draw, so a subquestion is "how to measure current draw", when multiple batteries connected to some "distribution copper bar"? You typically dont want any bit of power loss, but have to measure aggregated current from all the batts.. but that's worth another question. You may just comment on that topic briefly, so that I could do my own research, and not flooding questions in here. Thanks!


texts: Choice between Pseudo-Differential Unipolar and Pseudo-Differential Bipolar ADC Input

texts:
While reading about Pseudo-Differential Inputs for ADCs, I came across the  document below from LT. Link : http://cds.linear.com/docs/en/product-selector-card/2PB_sarinputtypesfb.pdf

Below are copied lines from the PDF:

"A pseudo-differential unipolar ADC digitizes the differential analog input voltage (IN+ – IN–) over a span of 0V to VFS. In this range, a single-ended unipolar input signal, driven on the IN+ pin, is measured with respect to the signal ground reference level, driven on the IN
– pin. The IN+ pin is allowed to swing from GND to VFS, while the IN– pin is restricted to around GND ± 100mV (Figure 2a).

A pseudo-differential bipolar ADC digitizes the differential analog input voltage (IN+ – IN–) over a span of ±VFS/2. In this range, a single-ended bipolar input signal, driven on the IN+ pin, is measured with respect to the signal mid-scale reference level, driven on the IN– pin. The IN+ pin is allowed to swing from GND to VFS, while the IN– pin is restricted to around VFS/2 ± 100mV (Figure 2b)."

Now the questions is, how do we make a choice between Pseudo-Differential Unipolar and Pseudo-Differential Bipolar. The choice should be based on the property and characteristics of the Input signal. For example, the input signal is a single ended sin function with range from 0 to 3V and a DC bias of 1.5V. Should we connect the IN– to 1.5V or to GND?


texts:
Question: I am designing the following common emitter amplifier. This is designed with a BC547B transistor.

My design is as follows:

Vcc = 15V, IC = 30ma, VRe = 2.5 V, VRc = 5V, VCE = 7.5V. HfE = about 200, VR2 = 3.2 V.

Ib = 1.5ma, Rc = 166 ohms, Re = 83 ohms, R1 = 7866 ohms, R2 = 2133 ohms. CE = 1uF Cap.

Cout = 47uF and Rl = 50 ohms.

I plug my electric guitar signal into the input and the signal actually comes out, but smaller than just straight from the guitar, measured with my oscilloscope.

I have read many books and none of them really address the issue as to what is the limitation in voltage swing when designing small signal amplifiers as the guitar's is about +- 250mv max with the low E-string. I.E what voltage swing will actually cutoff the base-emitter bias and essentially turn off the transistor.

This does extend as I am trying to amplify an incoming AM RF signal and have been unsuccessful.

Also, of course, any ideas as to why the circuit does not amplify the signal and actually diminishes it?

I'm obviously missing something here and I don't know what it is.


texts: Simple way to measure amps with a volt meter?

texts: I've got a simple voltmeter that I'd like to use to measure the power load of some components that I have no idea of. Some are simple (like an LED) and some are more complex sub-assemblies. I'm not sure how to use my voltmeter to measure the mA drawn by the component. I don't seem to be able to just touch the contacts on either side of the component and ground like I do when measuring resistance or voltage levels. Do I need to break the circuit and then use my volt-meter to connect the source to the load? That seems like a lot of trouble and quite difficult to do with soldered-on components and complex wiring harnesses. There must be an easier way. What do I not know?


texts: Why does my opamp circuit give only x10 overall gain

texts:
I designed the circuit below after a suggestion that I use two gain stages rather than one large stage with an expensive opamp.  This help keep the cost of my circuit down (the same application has been discussed in my previous questions).

My schematic is:

My thinking when designing the circuit was:

U1 buffers the Vcc/2 virtual ground (perhaps unnecessary to buffer it, but not harmful)
U3 should match the input impedance of 52 ohms and amplify x10 (OPA355 datasheet)
U4 should amplify a further x10

The input signal is 5Mhz and the circuit is on a PCB, seen below.

So for a small input of 10mVpp I expect approximately 1Vpp out.  I'll probably reduce the overall gain once I've done some testing but x100 is a good place to start testing.

With a 10mVpp input from a signal generator, checking TP2 with a scope shows virtually the same signal as the input.  Testing at TP3 shows a signal x10 larger than the input.

I assume I must have made a very silly basic error.  Therefore my question is: can somebody point out what is wrong with the circuit which results in only x10 overall gain.

Note I am not currently testing the comparator (U2), as I haven't yet integrated the data slicer discussed in my previous question.  Also I am using the same scope probe for all measurements, so I'm not mistaking x1/x10 settings by accident.


texts: Designing Buck Converter with Adjustable Output Current and Output Voltage

texts:
I am currently attempting to design a buck converter where both the output current and output voltage can be simultaneously adjusted. I will be utilizing an Arduino for control. I figured some sort of IC would be required to achieve this digitally (don't want to utilize manual potentiometer type designs). I am currently considering utilizing an LT8613 chip. Here is the datasheet for reference: http://cds.linear.com/docs/en/datasheet/8613f.pdf

Running a simulation for a digitally controlled voltage/current source with this chip, I am having trouble figuring out how to control the output V and I. I know the Ictrl pin is directly responsible for output current, and the feedback resistor network for the output voltage, but changing one is effecting the other quite a bit. To be more specific, I am considering utilizing digital potentiometers for the feedback resistor network.

Any guidance, tips, etc. on this would be appreciated. The application is a Lithium-Ion battery charger. Max output current of 5A, max output voltage of 4.2 volts. Also, can something like this be achieved without an IC?


texts: Bode diagram of a single complex pole and under-damped system

texts:
I would like to draw Bode plot for a complex pole as below. Let's assume that for now regardless that the single complex pole doesn't exist.
This is the function:

$$H = \frac{1}{s - (a + jb)}$$ where \$a\$ and \$b\$ are real numbers.

Now I would like to draw Bode plot of this transfer function.
First, substitute \$s\$ by \$j\omega\$ and we have:

$$H(j\omega) = \frac{1}{-a + j(\omega -b)}$$

From this I can calculate the magnitude and phase and draw Bode diagram.

I want to calculate break frequency (the frequency where the gain is 0.707 value of DC gain).

My questions are:

Is that method correct to draw Bode plot of a single complex pole?
Is my method of break frequency calculation correct?
Assume that I have a second order transfer function as under-damped system.
The transfer function has two complex poles. Does this mean it has two break frequencies?

Can I draw Bode plot of the under-damped system by plot Bode diagram of each single complex pole separately and then sum or subtract them?


texts: Identifying and calculating a load resistor of a multi stage amplifier

texts:
What is the load resistor in the circled stage of the amplifier? If there is a load resistor, what is it's value (either in strict numerical value and/or in terms of the stage's small-signal model parameters (such as gM and r0))?

The stage in question:


texts: Do I need to reset my FPGA design after startup?

texts:
I usually initialize state registers of my FSMs by specifying an initial value in my VHDL code, so that, I do not require a reset pulse after startup of the configured FPGA. The following example demonstrates this by a "ring-counter" which just merges all state registers together:

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity counter_init is
  port (
    clock : in  std_logic;
    msb   : out std_logic);
end entity counter_init;

architecture rtl of counter_init is
  -- large counter to detect excessive skew on Global Write Enable (GWE)
  signal counter : unsigned(255 downto 0) :=
    x"55555555_55555555_55555555_55555555_55555555_55555555_55555555_55555555";
begin  -- architecture rtl

  counter <= counter(0) & counter(counter'left downto 1) when rising_edge(clock);

  -- The counter value will be observed by an on-chip logic analyzer.
  -- Output most-significant bit to prevent synthesizing away the above logic.
  msb <= counter(counter'left);

end architecture rtl;

This technique has worked in my designs for Altera or Xilinx FPGAs so far. I have explicitly checked it using the vendor-specific on-chip logic analyzer and a startup trigger. Here is a screenshot of ChipScope, ok one cycle is missed apparently:

But, after reading the docs, I wonder how it works:
How do all the flip-flops (connected to the same clock signal) start to toggle at the same time?

The startup sequence for a Xilinx FPGA is described in the 7 Series FPGAs Configuration User Guide (UG470) for example. After configuration of the FPGA, a startup sequence is executed which asserts a "Global Write Enable (GWE)" Table 5-12:

  When asserted, GWE
  enables the CLB and the IOB flip-flops as well as other
  synchronous elements on the FPGA.

and in the footnote:

  GWE is asserted synchronously to the configuration clock (CCLK) and has a significant skew across the part. Therefore, sequential
  elements are not released synchronously to the user's system clock and timing violations can occur during startup. It is
  recommended to reset the design after startup and/or apply some other synchronization technique.

So, this actually means: If the clock at the flip-flops already toggles, then all the flip-flops may start to toggle at different times / clock edges. Given that the clock oscillator on the FPGA board is already running, and that I'm using a global clock-buffer without an enable input (BUFG): Will the clock input at the flip-flops already toggle before GWE is asserted?

I didn't find any information in UG470 about if and how clock-buffers are enabled. And the Xilinx 7 Series FPGA and Zynq-7000 All Programmable SoC Libraries Guide for HDL Designs (UG768) only states that the clock-enable input of a BUFGCTRL must be asserted synchronously. But, this is actually a user-driven input.

For the Altera Cyclone III FPGA I'm using too, I didn't find any relevant information in the Cyclone III Device Handbook.

To repeat: I didn't observed any failing initialization so far, but this seems not to be specified in the docs.


texts: What are the technical specs of the Nordic NRF 31512?

texts: can someone tell me what chip this is and where I can find the datasheet? Or at least if this is a custom fabrication, what chip from Nordic is it based off of? I've search high and low on the Internet and just can't seem to find any details on this tiny chip.


texts: How to calculate the high voltage power line trace clearance

texts: In my application the DC supply has rating of 1200V and 15A. I just want know the calculation for the trace clearance between power and ground.


texts:
simulate this circuit – Schematic created using CircuitLab

Q10 is equal to 10μC. No charge on C2. I need to find the amount of electric work that is converted into heat, from the moment the sw closes until circuit goes into stationary state.

Here's how I go:

Since there's no current in both states, we can disregard the resistor.
I calculate voltage of C1, when switch is open $$ U = Q/C = 2V $$
Switch closes, voltage is $$ E1-E2=8V $$ it divides on capacitors 4/3V on C1 and 20/3 on C2.
Use $$ We= 1/2*C*(ΔU)^2$$ Use it on both capacitors, sum them and get the wrong result, 70/3 instead of 15μJ.

What did I do wrong?


texts: Using Transistor to dump excessive voltage?

texts:
I'm way over my head with this and need a poke in the right direction.

I'm building a small hobby LiPo charger (I'm aware of the risks with a LiPo battery packs regarding usage, charging and discharging). And I figured, why not build in a >4.1v dumper circuit that grounds out any voltage above 4.1v but still feeds the 4.1v through the rest of the circuit.

I tried to do this with a transistor, hoping I could utilize a gate voltage of ~4.1v and drain the source. This would (obviously?) "break" the monitor output to the right seeing as there's less resistance to ground through the transistor, thus cutting off the monitor? Even that I would be fine with.
But running a simulator (NI Multisim) I'm getting a weird voltage combination instead of a over-voltage dump.

This is the monitoring part in the LiPo charger, where each Vs# is the individual cell-stack in the LiPo (5 Series LiPo pack in the example).

How can I feed excessive voltage to ground, but still feed 0-4.1v to the monitor gate to the right?

My end goal is also to combine all these voltage monitoring gates into 1 serial/digital mechanism so that I can feed the 5 voltages to a single Arduino port, would this be possible in any way shape or form?


texts:
I have 10 Cree XM-L RGBW LEDS and I would like to power them from a 12V power supply. I came up with this idea:

A 12V 30 amp power supply powers 3 different step down buck converters (10 amps each buck converter)
1st buck converter set to 2.25V (Red)
2nd buck converter set to 3.1V (White and Blue)
3rd buck converter set to 3.3V (Green)
then each diode is wired to its corresponding buck converter
(all 10 reds to 2.25V, all 10 greens to 3.3V and all 10 blues and whites to 3.1V)

The main idea is to control each LED from a DMX controller independently using this DMX decoder inside each fixture.

One of my main concerns is that in every circuit I've seen, they connect all the positives on the LEDs together to V+ and each negative is wired to a resistor and then to the controller R, G and B pins (with the resistor in-between). And what I'm doing is different. I'm wiring each Positive to its corresponding buck converter and each negative to the DMX board without a resistor. I'm afraid that I might burn the LED or something.

My questions are the following

Do I need to set a current limit? I know that any device will only consume the necessary current, so even if my buck converter is outputting 10 amps, it doesn't really matter because each LED will pull the required current (mA) right?
How should I connect all the buck converters and DMX decoder power? When using resistors, I've seen that they connect to the cathode so I don't know how to wire everything. Should I connect all the grounds together? The anodes to its corresponding buck converter?
Is there an easier way to do what I want? :D

SORRY FOR THE HORRIBLE DIAGRAM!

I hope this is enough so you understand what I'm trying to achieve.

Anyway I will try to edit this and make it more clear later, because it's 7 am and I have to go to sleep.

Thanks in advance.


texts: Why are the poles of the transfer function of the sinusoidal input signal always on the left side? I know that it makes the system bounded, but is there a way to understand it conceptually without going through the maths?


texts: Where do I get this regulator? Alternatives?

texts:
I am searching for this 3-pin IC.  It might be a low drop regulator switch. It is marked e3 N  1086 18 DR815.
It was faulty on a 42" LCD TV PCB. The TV could not turned on or switched from the standby to run mode. Hope someone can help me out what this IC is designed for and from which manufacturer it was and maybe you guys can show me an alternative part.


texts: Designing a M-Bus Master up to 10 slaves

texts:
I intend to design a M-Bus master which will be able to control minimum 10 slaves.
I started to search an IC with everything embedded (except supply of course) but I found nothing.
I discovered this scheme for 3 slaves :  but I would like to be able to control 10 slaves.

Do you have any reference for that ? What are the critical points ?

Many thanks in advance.


texts: Why are oscilloscope input impedances so low?

texts:
My question is two-fold:

Where does the input impedance come from?

I'm wondering where the input impedance of your average multimeter or oscilloscope comes from? Is it just the input impedance to the device's input stage (such as an amplifier or ADC input stage), or is it the impedance of an actual resistor? If it is the impedance of an actual resistor, then why is there a resistor at all? Why not just the input circuitry?

I measured the input impedance of my oscilloscope with a DMM. When the scope was turned off, the DMM measured about \$1.2\mathrm{M\Omega}\$. However, when the scope was turned on, the DMM measured pretty much exactly \$1\mathrm{M\Omega}\$ (I could even see the 1V test input applied by the DMM on the oscilloscope screen!). This suggests to me that there is active circuitry involved in the scope's input impedance. If this is true, how can the input impedance be so precisely controlled? Based on my understanding, the input impedance to active circuitry will depend somewhat on the exact transistor characteristics.

Why can't the input impedance be much higher?

Why is the input impedance of an oscilloscope a standard \$1\mathrm{M\Omega}\$? Why can't it be higher than that? FET input stages can achieve input impedances on the order of teraohms! Why have such a low input impedance?

I suppose one benefit of a precise standard \$1\mathrm{M\Omega}\$ is it allows 10X probes and the like, which would only work if the scope had a precise input impedance that wasn't unreasonably large (like that of a FET input stage). However, even if the scope had a really high input impedance (e.g., teraohms), it seems to me that you could still have 10X probes just by having a 10:1 voltage divider inside the probe itself, with the scope measuring across a \$1\mathrm{M\Omega}\$ resistor inside the probe. If it had an input impedance on the order of teraohms, this would seem to be feasible.

Am I misunderstanding the input circuitry of a scope? Is it more complicated than I'm making it out to be? What are your thoughts on this?

The reason I thought of this is that I've recently been trying to measure the common-mode input impedance of an emitter-coupled differential pair, which is much larger than the scope input impedance, so it made me wonder why the input impedance can't be larger.


texts: Why does the depletion region penetrate more into the lightly doped region in a pn junction?

texts:
I have read at several places if we take exact same cubes of p and and n doped semiconductor material and form a junction, the depletion region(blue colored region in my drawing) will be asymmetric around the physical center as below:

This means for some reason the doping difference in two materials shows itself in such asymmetry.

If correct, how could it be explained in simple terms?


texts: When a solder joint is reheated without applying flux, the solder might get dull. Or, when I solder a joint (maybe with the temperature set higher than enough), the solder looks shiny when melted, then turns dull upon solidifying. The solder joint might still have good electrical connection, but I just wonder what makes the joint not shiny.


texts: SIM card for SMS messaging application. Just pay per text (SMS) rather than monthly fee?

texts: I"m working on an app that uses text messaging (SMS) in an embedded application and I'd like to source a SIM card where I just pay per text (dont really care about the rates) but I refuse to pay a monthly fee for it.  Does anyone know of any SIM card suppliers where I only need text messaging and am willing to pay a lot for it ($1 per text) but no monthly fee.


texts: Voltage/Current varation according to the time and EMI

texts:
It is largely said that large voltage or current variation according to the time produces EMI. (Electromagnetic interference). When drawing the layout, care have to be taken on traces with high : $$\frac{dVoltage(t)}{dt}$$ and $$\frac{dCurrent(t)}{dt}$$.

Nevertheless I do not understand this principle. I do not know what is the relation between the current or voltage variation and magnetic or electric field. On the other hand, I can understand that large variation will lead to produce a lot of harmonics at high frequencies according to Fourier's theory. And so as the PCB are made smaller and smaller, the propagation will be easier as an antenna is perfectly transmitting/receiving when this length is equal to (if I remember correctly) to the waveform lenght divided by two.

Nevertheless, I do not know a formula which tells that the amplitude of the magnetic or electric field is higher if there is large current or voltage variation. The amplitude of the magnetic field or electric field space depends mainly on the current amplitude or voltage amplitude (and the distance).

So why no attention is paid on traces with high current or high voltage ?

If there is a formula which links voltage/current variation to magnetic/electric field, please let me know :D

Thank you for your help !


texts:
For randomness entropy I think I need some noise. My PCB is powered with 9V battery that's reduced to 5V using 7805 and I have a PIC16F15386 on it. There is little to no noise on the power lines so I cannot use that. My book on analog electronics says that zener diodes produces some noise, especially above 6V.
Question 1: Would it be possible to add a 7.5V zener to the board and use the PIC A/D to read the zener, and use the result as a start value for srand()? Or will that not be enough?
Question 2: The PIC uses INTOSC and I have the ability to use the clock out-pin. Can I feed the clock signal to the A/D and use that as a noise generator?
Are there any other ways I can explore?
EDIT: Added name of PIC.


texts:
I have a control problem with saturation. It is nearly linear in the non-saturation zone.

Problem:

Occasionally I measure huge error spikes. They must not disturb my control routine.
I want to get down to 50% (of the reference voltage) in my output voltage.
In the moment I do this by stepping one step up or down depending on whether the output is bigger or smaller than 50%.
This leads to oscillations.

Oscillations:

If I wait some bigger time before measuring the output voltage and then adjust the control voltage the oscillations go down. But this also extends my start-up time which is a problem as I don't know which control voltage value delivers 50% output voltage. I have to search quite a time.

How can I control the oscillations without slowing down my sampling rate?

In PID control it is said that the stationary error is reduced to zero if an integral part is added but how can I do something similar here?

Otherwise what would your approach to control this thing be?


texts: I am trying to PCB using a schematic I made

texts:
Routing isnt my strong point. I would like to know if this looks correct?

So I have 230V AC to 12V DC. I then have DC coupling, then an LED emitter, transimpedance amplifier, then active high pass filter, then a comparator abd finally a power transistor npn which will be connected to a 12V relay to turn a device of 230V.

Do the connections look fine? I want to distribute 12V power rail to each device so no voltage drop.


texts:
Below is the functional schematic that I am planning to use to control an AC load (air conditioner in this example with max current draw of 32A). Since I am still relatively new to mains power and relays, would appreciate if you guys can comment on the design and point out if I am missing something and whether this design is safe or not.

I plan to use a DPST Latching relay with coil voltage of 5V and max load current of 40A. The relay would operate on both the Live and the Neutral line for added safety
There would also be a 40A fuse on the Live line to protect against over current
A 12V Schottkey to protect against back EMF
A Hall sensor on the Live line to give feedback to the microcontroller on weather the current is going to the load or not.


texts: Why did they make the 74x170 (670) register file asychronous, no CLK input?

texts:
I am designing a retro computer as a project to learn digital electronics hands-on (not FPGA programming). I currently have an accumulator machine similar to the PDP-8 where the ALU has the accumulator register as one of its input, the other input comes from the data bus, and the output is clocked directly into the accumulator register on the rising edge.
I can use a 74LS173 for the register, or even a 74LS161 counter (as I do for the instruction pointer, IP). But I looked if I can just replace the single register with a 74LS170 (or 670) "register file", having 4 registers, but I'm missing the clock input. It's asynchronous like my 74LS189 memory. I am looking at the 74LS670 Data Sheet particularly the timing diagrams, and I can't seem to figure out how you could read from one of the registers, into the ALU and clock the result into the same register.
I would put read select (RA, RB) and write select (WA, WB) both at the same address, say 00. Soon the data appears on Q1,2,3, and 4. Soon the result comes out of the ALU. But the timing diagram shows -WE line go low before the data arrives! That doesn't seem to make sense. Why did they build it that way? It's even worse, according to this timing diagram the data output would appear even before I lower the -WE line.

This can't be true however, so what am I reading wrong? How did they use these register files without a clock? If I want asynchronous memory I could just use any SRAM chip.
UPDATE: It's been a veritable saga with me and these chips.

Open collector logic puzzle solved, a non-issue,
and moot with the '670 - Adapting the 74LS170 open-collector "register file" to active-high TTL input
Wondering of to convert it to positive edge triggered - part 1 - Turn a positive clock edge into a negative pulse to make a 74LS170/670 register file synchronous
Building the positive edge detector - Positive edge detection triggers on negative edge too
Trying to apply the edge detector and it doesn't work - How do I make a 74LS170 or 74LS670 register file reliably clock in data on the rising edge?

And after this circle (circus?) I am right where I started. Pulling my hair out why they never made an edge triggered register file and instead followed up the '170 with a '670 that is just as useless as the '170.
The only thing that's interesting is the dual port nature. So I can read a different register than I write to. This is the only thing that could make it somewhat useful, if the constraint is that you never write to the same register that you just read from in the immediately preceding clock cycle.
Or if you do, read and write from the same register, you must pull high the !G_W again right after the clock went high and before it goes low again. That means, I need to OR-gate this !LOAD control with a 90 degrees phase-shifted (delayed) clock, in addition to the CLOCK itself; so a 3-input OR gate:
!G_W = !LOAD + CLK' + CLK
Darn! That is complicated! So I still don't know what the use of those '170 and '670 ever was? And why the '172, which is edge triggered had been so abandoned that you can't even get an LS version for it (let alone HC?)


texts: Clarification on using software serial with AVR's

texts: Arduino appears to be able to use software serial on any pins you choose. I am trying to test the same scenario on an atMega128 however, all of the examples and notes I find require using the RX pin on External Interrupt 0 which is PIND0. I have successfully implemented TX on any pin I choose. My question is very specific. Can a RX pin for software serial be implemented on any GPIO pin I choose? If so, is there an example of how to test this. I Have not been able to get the RX working in my environment. Thanks


texts: prevent test/reset plug from tripping when electrical current stops?

texts:
I am installing an electric garage heater. The heater has a 120v wall plug with a test and reset buttons. I am plugging the heater into an outlet that is on a timer switch. Everything works as expected, however when the timer commences the wall plug trips and I have to press the reset button to get the heater to work again.

Is there any way to prevent the plug from tripping when electrical current stops?

Could I replace the test and reset plug with a regular plug?


texts: Bypass diode 1N5400 series on 48v system

texts:
I want to protect my dc motor controller from voltage spikes due regenerative braking. Battery is 48v (54.6v at full charge) li-ion chemistry 100A peak, with "cutt-off protection BMS" from overcharging.
Connection is:

48v/15Ah Battery
200A contactor with 470ohm 10W  precharge resistor
120A/60V Roboclaw controller
48V DC motor.

I also need bypass diode in parallel on positive wire between battery and contactor. I was looking for 1N5400 series diodes, and I'm in doubt. Should I go with 1N5400 or 1N5408 diode? Or something different? Do I need one diode on the contactor also?
This is wiring diagram, bypass diode is labeled D1, F1 is fuse, R1 is precharge resistor on the  contactor.


texts: Does an Oscilloscope's bandwidth need to match or exceed the microcontroller's/processor's clock speed?

texts: Looking to buy an oscilloscope for home use, I've seen the questions on here in regards to bandwidth. I'm interested in prototyping microprocessors with clock speeds 800+ MHz, but I shouldn't need an oscilloscope with that bandwidth, correct? Only for the external buses/peripherals, so if the memory bus was 100MHz then I'd need a scope with at least 100MHz bandwidth, so on and so forth. Do I have the right idea??


texts: In-amp output clamps to reference voltage

texts:
I am using AD8231 instrumentation amplifier in unity gain configuration. I used the inbuilt op-amp to provide reference voltage as the datasheet suggests. A 4.4kHz sine wave generated with my professional signal generator (PC sound card) is fed into the non-inverting input of the in-amp.

Channel one is the input signal and channel two is the output of the in-amp. For some reason the output clamps near the reference voltage (1.6V).

The circuit is built on a breadboard and I haven't used decoupling and filtering capacitors since I'm prototyping. Here is a photo of the breadboard in case it helps:


texts:
Can we make inductor in thick film technology to use as in hybrid micro circuits?

If so what is the wattage limitation?


texts: Step down converter stops regulating above 6V input

texts:
I'm currently using the following step down converter in a 4xAA battery powered design -> TPS62745

I have my Vselect pins configured as 3.3v out and using 4.7uH / 10uF combination on the output circuitry.

The coil I'm using has a Isat of 1.75A: 4.7uH and my load is 80mA max

When I increase my Vin to 6 volt and more, I get these dips and increasing Vin results in the same dip line but lifted upwards.
So it doesn't regulate 3.3v anymore.
Vin on the scope screenshot was 6.6V and output 3.76V already.

I replaced the cap to a 22uF and also tried 6.8uH coil but nothing changed.
The dips are every 100ms.

What is going on here?


texts: Can liquid soldering flux be refrigerated?

texts:
I've been upgrading my soldering mojo lately and have collected an assortment of liquid fluxes.

The Kester 951 and Kester 186 datasheets state shelf lives (1 and 2 years respectively) when stored between 10-25°C (50-77°F).

I store my solder paste in the fridge, which is between 2-5°C (35-40°F).

Is the liquid soldering flux safe in there too? And would keeping it there extend its shelf life?

Also I guess I don't know how I could tell it had gone past its prime. What would be the signs it had "expired", whether or not the shelf life period had elapsed?


texts: Using velostat instead of a force sensing resistor

texts:
I am trying to make an input device that will communicate with a game. The device will be incorporated into a phone cover. I want the user to be able to squeeze the cover...similar to how you would squeeze a stress ball. I have made a stress ball with an FSR incorporated in it. What I did notice, however, was that sometimes the values from the FSR changed. Like on day 1, the range would be 100 to 1020 and then on another day it would only go to 500. I thought it was the battery supply that was responsible for this but the circuit had a 5v regulator component as well, so the input voltage was maintained at 5V.

Now that I am using a phone cover, it will be tough to incorporate an FSR as the FSR also has really weak legs and this might not make it very durable or resilient for daily usage.

So my question is : could I perhaps cover the phone cover in velostat and use it in a similar manner to an FSR? Or should I stick with the FSR and find a way to work around the aforementioned issues?


texts: Voltages at Secondary Winding in Centre Tap Full wave rectifier

texts:
Let N1 turns in the primary winding, N2 turns in the secondary winding.After centre tap, the turns ratio becomes half of secondary winding.In textbooks given that the voltages of the upper winding and lower winding are equal with that of the input with 180 phase diff.
but my doubt is that If the turns ratio becomes half, Voltage at upper, lower part of centre tap should be half that of the input.
how it possible to have the same voltage as the input?


texts:
I am building a battery powered device. Almost all of my logic is running at 3.3v, although I do have a 5v supply for a few hobby servos.

I want to measure the battery voltage, but I can't do so directly with the ADC on my controller because the battery voltage (depending on the cell count of the lithium polymer battery that the user connects to the device) can vary between 6 and 36 volts. (My 5V and 3.3V supplies are fine with this input variation already.) The ADC can't measure anything above its supply voltage.

Obviously I need some sort of amplifier with a fractional gain, about 1/12 or so. Should I just use a simple voltage divider? How do I decide what values to use? Maximizing sleep-mode battery life is a concern, so that votes for using large values. What constrains how large those values can be? (The input impedance of the ADC, right?)

Am I better off using some sort of opamp amplifier circuit for some reason?

What's the usual solution here?


texts: Centering joystick potentiometers in a controller

texts:
I've replaced a joystick in my Dual Shock 4 controller, because it was getting stuck. The readings of the new joystick are offset to right and down.

I've read that you can recenter the readings by reseting the controller but that didn't work.
I was thinking about soldering another potentiometer in parallel and live adjust it to make the stick read center and then desolder them, measure and replace them with SMD resistors of similar value. Would that work? Should I try something else?


texts:
I want to build an inverter and currently I am in the processing of choosing the right MOSFET. To achieve this I use simulations to compare the total power dissipated on the MOSFETs, to see which one has the lowest.

In order to truly see the best results and the "competition" to be fair, should I be using the same value for Rg (let's say 10ohm), or should it be proportionate to each MOSFET's Qg. I'm thinking the by adjusting the Rg I am eliminating the Qg from the equation and the results will be based on Rdson.


texts:
We've currently got a PCB that needs to power a modem and a microcontroller. The PCB is powered via a battery (12V - 30V range). The  modem and the microcontroller have separate power lines. The microcontroller + peripherals consumes about 200mA, while the modem can consume about 300mA (with spikes of 2A during transmission bursts).

During the design phase it was obvious that a step down switching regulator would be the preferred solution, as an LDO would need to dissipate too much heat. For an initial revision however, the PCB was designed in such a way so that we had the option to use either

LDO : LM317
Stepdown converter: PTN78000WAH

(The reason being that the LDO was a lot cheaper to design / manufacter) and that the modem was only used a couple of times per day for really short periods of times (sending about 5 x 1kb per day).

The reason being that it was unclear what the cost would be of a decent switching regulator design.

We've tested with both and indeed found that the LDO needs cooling when heavily used. Obviously using the PTN78000WAH buck is not possible from a pricing perspective (14 eur).

We're wondering what the uptick would be compared to the LM317 LDO if we were to go for a switching regulator. Our PCB designer isn't clear on this, stating that a switching regulator design is very complicate, requires additional research and a proof of concept that we need to pay without have any idea what the impact on the final cost will be.

We just want to know what the pricing impact would be if we opt for a switching regulator on the PCB.

The reference design of the modem proposed the following:

We already have the fuse, diodes, caps, ferrite bead in place on our PCB. The only thing we don't have is the L101 (a inductor/ choke), as this is currently on the Texas Instruments breakout board.

Is it as easy as looking at the price of the 2 core components:

DC DC Converter LM3596S
Inductor B82111EC22

And conclude that for about 3EUR (as opposed to the current 0,3EUR) we would be able to put a switching regulator circuit on our PCB ? Or is there still something else I'm missing. And are there other alternatives for the 2 components above that might be suitable for our use-case (powering a SIM900 modem, 12-30V input, 2A current during transmission bursts, 300mA normal operations) ?


texts: Calculating the real and reactive power of a transmission line

texts:
I have a single machine connected to an infinite bus with the following parameters:

Sending end power = 3.75MW
RL=5.18 ohms
XL=130 ohms
VS (Generator bus)=161kV
VR (Infinite bus)=161kV
Sending end voltage angle (delta) = 0.01877 (Angle which allows 3.75MW to be transferred)

Using these I want to calculate the amount of reactive power sent by the sending end as well.

I calculated it first without factoring in the line resistance (RL=0) Then got the result for Q as : 35.24kVAR

Next I calculated it with the line resistance factored in Then got the result for Q as: -114.77kVAR

When the line resistance is factored in, the answers for reactive power vary immensely. And when the resistance is factored in, the sign of Q is negative indicating the generator bus is absorbing VARS which doesn't seem to make sense.

Why are they so different? What am I doing wrong?

The equations I used are here

I derived these equations using Matlab to do the algebra, so it hopefully should be correct :)


texts: How many 115ah wet lead acid batteries are safe to charge in the same space?

texts: We are using about 10 115ah wet lead acid batteries to provide electricity for our business in the field. At night, we charge them all in the same space. The space does have a bit of airflow, but it's not like we are leaving a window open. Is charging this many batteries together in close proximity safe? I am asking due to the gases that are given off by them all while charging. Thank you for your help!


texts:
I will be using the OPA694 for some video processing. I would like to know how much delay it introduces, so I can account for it. Here are some specifications of the op-amp:

Rise Time and Fall Time    G = +2, VO = 0.2 V  Step 0.8 ns
Settling Time to 0.01%     G = +2, VO = 2 V    Step 20 ns
Settling Time to 0.1%      G = +2, VO = 2 V    Step 13 ns

I won't be using a 2+ gain, only a +1. My signal will be an RGB line and range from -0.3 V to 0.7 V. A rough estimate will do, and as I understand it can vary with the application.

I'm asking this because I'll be taking an input which will be roughly 35 nanoseconds behind, delaying it to sum it to another signal. E.g. Sync is 35 ns late and RGB are all on time 0 ns. To add sync to G, I will delay G 35 ns and use an op-amp to add G and sync together. The op-amp now means line G is 35 + x ns behind R and B at 0 ns.

Also, how much does 1 ns matter in video? If it is less than a pixel it's fine.


texts: ODT Termination and driver impedance Question

texts:
I am analyzing signal integrity between an applications processor and DDR3 modules.I was looking at IBIS models for the device I am using. I was confused because certain IBIS models had "driver impedance" and certain ones had "ODT" - (on-die termination)

In that context, would anyone be able to outline the difference between termination impedance and driver impedance?

Thanks


texts: What is the function of a capacitor in a motor circuit?

texts: I read a manual of how to connect a speed controller to a motor. I see there is a capacitor as shown below. My question is what the function of the capacitor is? Thanks


texts:
I have a RF remote control for the garage that I would like to control via Arduino.

With a multimeter, I detected around 3v across the button.

I have soldered two wired on either side of one of the buttons, and connected one side to digital pin 12 and the other to ground.

While this worked fine, I did notice that the remote depleted of all battery in a day.

Trying to marry theory with practice, did this occur because I did not use a pull-up / pull-down resistor?

Update

As recommended by Cornelius, I removed the battery and connected the 3.3V and Ground directly to the battery terminals.

As Andy Aka predicted, I measured the voltage from ground to the positive terminal of the button, and it is ~5V, which will end up damaging the board.


texts: Surge protection for ADC inputs measuring DC from batteries and switching supply?

texts: I'm working on a circuit that senses AC presence and measures DC output from a switching power supply and a battery. They will stay inside a grounded metal case but out in the field, so the AC mains are already protected by a varistor and the AC presence sensor is opto-isolated, so I guess that is enough for the AC detection part. For the DC measurements though, on my prototype I'm just using a resistive voltage divider to scale down the battery and supply levels to the ADC range, but I'm wondering if any protection would be recommended as well. The measurements are taken on the switching supply and battery charging outputs, so they are already somehow isolated from the AC input. No wiring or sensor inputs are coming from outside the metal case apart from the AC mains, so, do you think any protection would be recommended on the ADC inputs other than clamping diodes to the ADC voltage input rails?


texts: Triac drivers with or without zero-crossing detection

texts: I've been looking at this schematic for triac control by varying the gate pulse timing. The description states that the triac switches off automatically at zero crossing and when there is no gate pulse. Does this mean this a zero-crossing detecting triac driver? I looked up the datasheet for the triac listed there (MOC3052-M) and it states that the opto circuit is couple to a non-zero crossing triac driver. I'm a little confused.


texts: Efficiently rectify 18-20V to 12V AC-DC for wireless charging

texts: Connected to terminal J1 is a wireless charging receiving coil (18-20V AC). Is there a more efficient way to produce 12V DC from this with enough power to drive the charging circuit and wifi comms (not shown).


texts: Power supply fails when PWM an halogen lamp

texts:
In this video I'm trying to light a 50W 12V halogen lamp using PWM, and switching from 0/500 to 500/500 duty cycle within 15 seconds (31000Hz frequency). I'm using an ATX power supply  (276W spec on 12V rail), a MOSFET (IRF540N, "33A 100V 0.040 Ohm N-Channel UltraFET Power MOSFET"), and an Arduino Mega controller (wire going directly from chip PWM pin to MOSFET gate).

System works a treat when below ~300/500 duty cycle or above ~400/500.
System works a treat with led strips attached (instead of halogen lamp), I suspect they draw about 15 W (no specs available).
Power supply turns off when around ~350/500 duty cycle (problem I'm asking your help for).
I haven't got to measure the lamp resistance when cold (Fluke 106 multi-meter shows same reading for both the halogen lamp resistance and the multi-meter probes touching each other directly).
I haven't got to measure power draw/current (I'm afraid of blowing the 10A multi-meter fuse).
I haven't got an oscilloscope.

I was wondering how could the power supply withstand the load of a colder halogen lamp when around 200/500 duty cycle or a fully powered lamp and not a 350/500 duty cycle (if power draw was the one causing the power supply to fail).
I was wondering if there were any other plausible explanations for my problem that I should be checking for.
I was planning to buy a new ATX power supply to connect 6 of this lamps in parallel and needed to solve this problem first/learn the required specs of the future power supply.
I liked the idea of using PWM and not a dimmer (not messing with 220V, avoiding lamp transformers magnetostriction noise when dimming the lights, learning of the problems I'm encountering ATM).
I wanted to thank you all for your patience and hope somebody else finds this thread useful!


texts: Measuring Power Amplifier with Sound Card

texts:
I'd like to measure the frequency response of my power amplifier, while it is connected to a loudspeaker.

The power amplifier outputs at +- 50V, and I think the maximum input of the sound card is approximately 1.5V.  The input impedance of the sound card is 1 K ohm or 1 M ohm (there is switch to select the impedance).

I think the first step is creating a voltage divider, and match the impedance with the input impedance of the sound card.  The next step is -- since I can't afford replacing sound cards for every mistake I make -- is add some zener diode protection.

Is there anything I'm missing, or any other protection I should add. The circuit I've got so far:


texts: Determining frequency of self-drive piezo oscillator circuit

texts:
I have the circuit below, and I am wondering how the resistors and capacitor alter / determine the frequency that the piezo element vibrates at. I am assuming that they make a difference but I can't find any information pointing me in the right direction.

simulate this circuit – Schematic created using CircuitLab

Note that the values currently there were given and no explanation as to why they are so. Any guidance as to what controls the frequency of the oscillation would be greatly appreciated!

EDIT
That datasheet / catalogue for the piezo can be found here.
Additionally, the product page with more specifics is here.

I don't know what properties play a part in this calculation so any guidance in this would also be appreciated.


texts: Difficulties in biasing MOSFET push-pull amplifier

texts:
Everything works perfectly well and following the expected in the simulations on MultiSim.

This is what the test-version of my circuit project looks like:

I made this version of the circuit to correctly bias the MOSFET's and to get the DC operating points correct before connecting the sources together to use it as an power amplifier.

In the simulation, the VGS of the IRF530 is 3.6 V, the VGS of the IRF9530 is -3.3 V and the voltage between the sources (the voltage over the output resistors) is 0.26V.

It works fine as an amp (in the simulation) when injecting signal on the base of that BD140. No distortion nor frequency-related problems.

But that's what I got when making the actual circuit:

Ps.: In the actual circuit I use an IRF540 and an IRF9540 instead.

I got the voltages the same at the gates of the mosfet's, but now the output is totally different.

The VGS on the IRF540 is 3.2 V, but the VGS on the IRF9540 is 20.5 V (positive, which is even worse).

Somewhy, the IRF9540 seems to be completely allowing current to flow between its Drain and its Source, the voltage between them is reading 0V even in the milivolt scale of my multimeter (And that's why VGS on it has the same value as VGD).

I also tried to simplify things to see if it had some kind of instability, I did this:

In this circuit (in the simulation), by adjusting the potentiometers to get the same values on the mosfet's gates as before, it works exactly as it did before.

In reality... I get the same exact behaviour it had in reality before too. Still the same problem.

I also tried playing with the potentiometers and found no point where the circuit behaves minimally similar to the simulations. The VGS of the IRF9540 is always positive and it's always conducting even with at a positive VGS.

Both MOSFET's are mounted in a heatsink and I checked for any kind of faults in the circuit - Everything is correct.

I also replaced both of them and nothing changed, they're not malfunctioning.

According to the simulation, nothing even close to that should happen even if the values were a bit off.

So, any ideas?

Thanks!


texts: Does a RFID antenna need to be FCC certified?

texts: Being a RFID UHF antenna a "passive" element does it need to be FCC certified? Or, we just need to have the RFID UHF reader certified?


texts: What does overlaping indicate in i2c timing diagram

texts:
I am studying how i2c devices works...and I have downloaded a power point presentation from Google,

I have understood almost every basic concept, like, how the start and end of the transfer occur, what is SDA and SCL and what is master/slave.

but in this timing diagram,
SDA supposed to show the transmission of data bits, i do not understand how the two lines of transmission are displaying in the SDA here which are over each other. shouldn't it be a single line for SDA too ?
also, what does the dashed line indicating here ?


texts: How to find the Lithium Contents of a Metal Battery, by knwing only the VOLTS

texts:
How do we find the Lithium Contents of a Metal Battery, when the Batteries show only the VOLTS.

As per the IATA DGR, Metal Batteries can be accepted only when the Lithium contents are known ;  but the Batteries do not show the Lithium Contents, it shows only the Volts.


texts: How to design Digital logic gate using TFET logic?

texts:
In my recent project, I need to design digital logic gates using TFET instead of CMOS logic.
Can someone Suggest any simulator or procedure which support design using TFET logic?


texts: Is there difference in connecting these two jack connectors?

texts:
I'm making a pedal from this tutorial https://www.instructables.com/id/Overdrive-Pedal/ and the author is using this type of jack female connector:

But I already bought this type of connector:

The author's connector has 3 tabs to connect, and in step 13 he said:

"Connect the black wire from the 9v battery snap to the remaining unused tab on the stereo jack."

But I'm an amateur and I do not know how this connector works. I already used the 2 tabs to connect other wires, and there's no tab left. Is there difference to connect all wires to the same tab, or are these tabs only a method to organize my wires better?

Will this connector still work (in my case) when the connector has only one tab and I connect all wires in the same tab?


texts: How does a rocking arm voltage regulator work?

texts:
I am trying to determine the suitability of replacing a (ancient) rocking arm voltage regulator with a modern digital device.

I assume a rocking arm regulator has an electromechanical or magnetic feedback mechanism, but I have not been able to find a detailed description of its operation or much information on how quickly such regulators respond to transients.

Does anyone with experience have an explanation of how they work? Are these devices mag-amp based? Are they known by any other names?


texts:
I am trying to fix a hair straightener and I found what appears to be burnt resistors.
They are surface mount but they don't look like surface mount. They look like a mini version of your regular metal film resistors. However as far as I can tell they are 51 Ohm (Green, Brown, Black, Gold), and used in mains voltage (240V). So I am thinking they are high wattage variety of some sort. My local Jaycar didn't have a clue. Can someone here help me source this component or a substitute?

(It's about a centimetre long)


texts: UL 508A - Listed assembly in unlisted enclosure?

texts:
I need a UL Listed industrial control panel (cf. UL 508A) with non-standard dimensions. I understand that "508A" shops can fabricate Listed enclosures in custom sizes, but that takes extra time and expense.

Can an industrial control panel be UL Listed if the enclosure itself is not UL Listed or Recognized?


texts:
I am looking for a PIC which has a webserver builtin or has the ability to install one(with) . I want to experiment connecting  in reasonable price please)two PIC/PICAXE boards or different type and send data from one to another. I will be running a server program in the webserver where I want to capture the data sent from 2nd PIC board.

Thanks.


texts:
I've got an old Sony Ericsson with a charger that's sustained some damage. The cord has been melted and flattened in one place. Neither the charger nor phone has been used in a long time. The battery for the phone is not charged and at right now the charger doesn't seem to charge the phone.

Using a multimeter, I tested the voltage on the pins of the charger. I get the correct 5V readout. This leads me to believe the charger still works. However, when I try to read the amperage from one pin to the other I always get zero. Can anyone tell me why this might be?


texts: DC Motor control setup and circuit design. 1.5Hp continuous duty @ 95v dc

texts:
I have a DC treadmill motor rated at 1.5Hp @ 95v Continuous duty, though the motor label also states that it is a 2.65HP motor and that the amperage is 21.4.  I would like to be able to SAFELY run and control this motor from a standard American household outlet to spin a rotor for a project.  I do NOT have any of the original components from the treadmill it came off of, but after a bunch of research I have ordered some parts, and want to make sure there aren't any extraneous factors that may cause it to function improperly, or draw too much current due to DC motor start-up current draws, not enough resistance, etc.

I will likely run this motor from a 20amp(based on the circuit breaker) circuit in my garage.  The design is as follows, and all connections between components are made with 12 gauge Copper wire unless otherwise specified, and each wire section being no longer than a few feet, mostly around 1-2 feet.

I have a 15amp(rated)replacement male plug end(so i can hook it up myself) coming from the wall outlet that will be connected in line to a 20 amp Circuit breaker(acting as my on/off switch) connected to a 4000Watt(as per manufacturers specs) SCR Voltage controller (0-110V).  This in turn will  be connected on the output side to a 1000V/50Amp Full wave Bridge Rectifier with heat sink, which will connect to the motor via the 16AWG wire coming out of the motor itself(it came with those wires attached)

Assuming I don't heavily overload or stall the motor in some way, is this a safe setup?  Are all of the components rated with enough power/amp/volts to safely run the motor at all voltages?  Is it safer to switch on the motor at low or high voltage on the SCR controller and why? I am a little fuzzy if the lower voltage means higher amperage because of ohms law, or if the higher voltage means it will have a stronger reverse EMF and cause higher amperage draw.  Any help and explanation would be appreciated.  I speculate that the lower the startup voltage from the SCR controller the better, but I just want to make sure.  Are there any additional components that I would need to make this a safe and useful setup?  I would be happy to provide links to specific parts for reference if my information isn't enough.  If there are better or more cost effective ways to be able to accomplish the same speed control/level of safety, please let me know as well, total cost of project not including motor or wires is ~$35  Thank you for the help.

EDIT TO ADD: The DC motor controllers I saw on amazon were seemingly not rated high enough for my purpose, either not a high enough voltage to be able to handle Mains voltage or provide the 90+ volts, or not enough watts for the rating of the motor.  This is the SCR I intend to use, rated at 4000Watts 0-110 Volts: http://www.amazon.com/gp/product/B00MKU4W3Y/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

EDIT TO ADD: I spoke with an Electrical engineer and he mentioned a Variac, and ideally I would love to use a Variac, but the ones I saw available that can handle the 20+amps are in the $200+ range, and far beyond my budget.  Seemingly the 4000W at up to 110 volts means the SCR I intend to use can handle up to about 33amps which is enough for this project if my math is correct, and far less expensive. ~$18


texts:
I'm trying to simulate a relatively simple AC->DC power supply in LTSpice, but it's not quite cooperating with me. I've followed this schematic:

only replacing potentiometers with resistors due to my lack of LTSpice knowledge.

Now, as you can see in the image above, I'm not exactly getting a clean DC signal out... What am I missing here?

Since my LM317 component isn't part of the schematic, I'll just upload a screenshot unless you really need the full file; however, it should be irrelevant as the same problem occurs even if I cut everything to the right of the 2200µF cap away!

Am I missing something in the design itself, or is this plainly a simulation problem? In either case, any suggestions on what is wrong?


texts: Capture Analog Audio Output from a two-way radio?

texts:
I am trying to record audio that is from a two way radio, which is equipped with a d-sub 15 pin accessory connector.  I know pin 2 outputs analog audio at -10 dBm @ 600 Ohms, so what do I need to do in order to use this signal?

Service Manual for Radio With Pin Description


texts: Issue replacing 27C256 ROM with 62256 RAM

texts:
I'm trying to replace a 27c256 ROM with a 62256 RAM, to be able to easily change the memory content. I thought this would be pretty straight forward. Not quite, it seems.

I made an simple experimental PCB which is build around the 66256 RAM chip. On one side you have the connection to the target device, of course I made sure I rewired pin 1 with pin 27 to make sure A14 is in the right place.
On the other side I have a PIC MCU with a RS232 connection to a PC which takes care of the programming and verifying of the RAM chip. To start of simple I placed DIP switches betwheen the RAM chip and both sides (Target device and PIC) to make sure the two aren't interfering with each other. My idea is to replace this with some type of octal latches eventually.

After I programmed and verified the RAM chip using the PIC I isolate the 62256 from the PIC and open the DIP switches towards the target device. I make sure I keep the /WE pulled up and the /CE pulled down. The /OE is strobed by the target device just as it does when a regular ROM is connected. However the target device does not run the program.

This while the program works fine when burned to a ROM.

What am I missing/forgetting?


texts: My oscillator of 40Khz is not giving 40Khz signal at the output

texts:
I am putting a 40Khz crystal oscillator with 33Pf load capacitors.
 The problem I am facing is that as soon as I switch on the circuit, it is not giving me the pulse but as soon as i touch a metal or my hand on one of the pins, it begins to give the pulse. Is it a faulty Oscillator or I am doing something wrong. The circuit used to work perfectly fine with the other Hardware PCB I am using.

This is a very weird problem for me. Kindly help.


texts: Difference between Peak rectifier vs Full wave rectifier

texts:
I asked a question the NXP forums here about the TEA2208T (datasheet) which is an active bridge rectifier. I was told this part is a full wave rectifier and not a peak rectifier and therefore a rectified AC voltage would look like this even with a smoothing cap after rectification:

Where a peak rectifier's output would look like this with a smoothing cap:

I cant really find anything on "peak rectifiers", never heard of that term before either. I typically hear what the NXP rep calls a "peak rectifier" as a "full bridge rectifier"

How would the two rectifiers produce a different output even with both having a smoothing cap? My understanding is the active bridge rectifier does the same thing as the diode bridge but at a higher efficiency by essentially replacing the losses from the forward voltage drop of the diode with the Rds_on from the mosfets? I would think no matter how I get to the  rectified AC signal, placing a smoothing cap on the end would produce a DC output.

Edit (to respond to Cristobal's answer):
So I believe I understand now. Say for the positive half cycle of the ac input, two mosfets will conduct and we can idealize those mosfets as a normal conductor like so

Which is simply (image edited to remove cap value and clarify the voltage source is not vcc)

So the cap just follows the input voltage even as the input voltage drops below it's peak value. Where as in the diode bridge configuration, the cap will charge to the Vpeak value (minus Vf of diode) and once the input drops below Vpeak then the diode stops conducting and the cap is essentially cut off from the input and discharges at the rate of it's RC time constant rather than following the input voltage like in the mosfet bridge.
Edit #2:
Looking at their eval board for this part they show the output waveform of the IC eval board

The body diodes do the initial rectification and you can see that the output signal is DC for the first cycle. After that first cycle the mosfets kick in and take over the rectification. And you can see that you no longer get a DC output but just rectified AC.


texts: What is the purpose of a 380/220V control transformer when you could just use one phase and a neutral for your motor control circuit?

texts:
I've seen a control circuit that uses a transformer in the plant. The supply voltage is 380V. What is the reason for this? Would it not be easier just to tap one phase and use neutral as your return path in order to get the same 220V?
Infact, what is the general purpose of using a transformer for the control circuit? Maybe that's the point I'm missing.


texts:
I'm studying the schematic for the constant current/constant voltage (CC/CV) indicator on an Agilent E3610A:

My question is: What purpose is served by the 10kΩ resistor (R26, R16) on the non-inverting input to the LM393 comparator?

The circuit operation is pretty straightforward. When the constant current error amp (U4B) is controlling the pass device, it's output voltage is around -1V. When the constant voltage error amp is controlling the pass device, the constant current error amp output jumps up to near the positive rail, say 14V in this case. The inverting input to the comparator (U5A) is set at around 12.3V. So the LED comes on when the constant current error amp is in control.

The thing I don't get is why a resistor is required between the error amp (LM442 op amp) and the comparator input. The input impedance of the LM393 is megohms, isn't it? What difference would an extra 10k make?

The only hypothesis I have is that I understand from the datasheet that if one of the inputs is driven more than 0.3V more negative than the negative supply, that as much as 50mA can flow out of the input pin. So I suppose this might be a safety precaution; but I can't work out what anticipated condition would drive that voltage down that far since it uses the same supply rails. So that possibility isn't making much sense to me.

Can anyone help me understand why the design engineer might have added these resistors?


texts: Lithium Ion charging problems - power outages

texts:
Does any one know if general charge circuits for lithium ion batteries suffer from this problem:

-Flat Battery put on to charge.
-A power outage of long duration occurs (say 8 hours).
-When power comes back on, the charger won't charge.
-The charge refuses to charge until batteries are disconnected and then reconnected.

Where do you think the charger is getting stuck?

On a voltage or current measurement?

Or is it typical for the battery to have to disconnect before it can 'restart' and reinitialise its measurement values?


texts: Will this setup create much audio interference for me?

texts:
I'll be installing a ipod adapter kit in my 2004 honda accord, and on the device that connects to my stereo, it includes stereo outputs - red/white - that i can connect with a stereo to 3.5mm cable to plug in any other device and listen to it through the stereo.

My question is, since I bought a 6ft cable without really thinking, will I get much interference from winding up the cable in bunch to fit it under the stereo? As opposed to just getting a shorter cable.

Here is the cable for reference: http://www.amazon.com/Belkin-Audio-Cable-Splitter-1-Mini/dp/B00004Z5CP/ref=sr_1_5?ie=UTF8&qid=1323873682&sr=8-5

This is the interface that I will be installing: http://www.amazon.com/USA-PA15-HON2-Interface-Select-Factory/dp/B001JT5G4G/ref=sr_1_1?ie=UTF8&qid=1323879039&sr=8-1

Wasn't sure how much self-interference from the cable being bunched up together - like in the amazon pic - I would get, if any.