texts: Calculating base current and resistor required from transistor datasheet? Do I need a different transistor?

texts:
I am extremely new to circuits and using transistors, but after reading many other posts and articles I am still confused about terms and not sure if I am understanding this correctly.

I have been trying to use raspberry pi to use as a switch to turn on a motor. However I realized that I could not use PN2222 as the current limitation IIUC is less than a few hundred mA, much less than 1.5A. So I have been trying to get a new transistor but have been very lost on reading the datasheet. After much research, I think I have the basics, but wanted to double check from the experts here whether what I am doing is not going to blow anything up.

My main guide has been this post: Need help calculating resistance for transistor base

(Tried to simulate this but I don't seem to be getting any useful data - getting 0 V everywhere or N/A)

simulate this circuit – Schematic created using CircuitLab

Datasheet: sheet

Questions

So the motor I have is 12V which takes in minimum 1.5A. Using I=VR, does this mean that the resistance is 8Ohm and so I should use 8 Ohm in my calculation?
If I understand correctly, to calculate how much current is required from base, I need to use \$h_{FE}\$. At 1.5A collector current, gain is approximately 30 (from the graph, although I am not sure how that \$V_{CE}=4V\$ actually affects anything). So to support 1.5A, does that mean \$I_b\$ needs to be \$\frac{1.5A}{30}=50mA\$? If the max the source can output is 16mA, is the max current going through collector->emitter \$16mA * 30 = 480mA\$?
So the base resistor required would be \$R=\frac{V_{BaseResistor}}{I_B}=\frac{3.3V - V_{BE}}{50mA} = \frac{3.3V - 1V}{50mA} = 44Ohm\$ But since I can't do 50mA, do I just calculate this for 16mA?
From the calculation above, it seems like I can't actually use my current setup to enable the motor properly. Is this correct? In this case, is it better to get a new transistor (is there a way to find correct transistor more easily?) or is it possible to provide external power to increase amperage provided to transistor?

Sorry if my questions seem all over the place I'm still very confused whether whatever I am doing is correct.


texts: Why is current flowing mostly through the base (NPN transistor)

texts:
I am currently working to install an NPN photoelectric sensor (retro-reflective dark on: https://www.automationdirect.com/adc/shopping/catalog/sensors_-z-_encoders/photoelectric_sensors/18mm_round_-_nonmetal/polarized_retroreflective_(ss_-z-fa-z-_fb_series)/fbp-dn-0e) however it is not working as expected and was hoping someone here could clarify what is happening. To my understanding an NPN transistor works as so (RL is 9k ohms). Here the transistor is activated.

What is happening is the current Ib is 0.016A when the transistor(sensor) is on and 0.12A when the transistor is off. Ie is 0.018A when the transistor is on and 0.012 when off. Ic is essentially zero at all times. The impedance reading between the collector and emmiter is 38.5M ohms at all times, and the impedance reading when taken across RL (base and collector) is overload and then when the sensor is activated the resistance of 9k ohms is read.

My question is although the logic is working as expected, the currents (Ie, Ib and Ic) are not. I was under the impression the transistor acted essentially as a switch between emitter and collector, however most of the current flow is through the base and the emitter, and the impedance between the collector and emitter is not dropping below 38.5M ohms. Can anyone clarify anything for me? Or is it likely I have screwed up the circuit or am taking incorrect measurements. Thank you.


texts: Protect ESP32 GPIO from ESD events, resets on inputs!

texts:
I'm working on a product that uses the ESP32 WROOM module.  There are 6 exposed pins that user can touch, shown by the header attached.  There is a piece of plastic that slides across a plastic housing, and makes contact with some metal contacts, to short some of the pins together to make a selection (binary math counts the number of on/off etc).  Anyhow, there is a static charge that builds up as the two plastic pieces slide, and as soon as the metal contacts touch, the ESP32 will brown out and reboot.  It's not software, it is for sure ESD (can wet the plastic and it stops).
I've tried researching the best I could, and this circuit does not seem to stop the reset sequence from occurring.  How can I stop this?  we do not have expensive ESD testing equipment, just an oscilloscope.


texts: could I just add a microcontroller or timer to this transmitter circuit to turn it on and off so that it lasts longer?

texts:
I am thinking of making my own UHF tracking transmitters for a wildlife study.

Could I just connect a low power microcontroller to the Vcc part of this circuit
http://www.instructables.com/id/Tiny-UHF-Tracker-Transmitter/
 (e.g. Attiny85) and program it to turn the transmitter on after 10 days for a couple of hours every afternoon only (i.e. during the time when I'm searching for the transmitters)?

Or are there other considerations I haven't thought of here.  I'm very unfamiliar with radio.   If someone has other suggestions on how to significantly increase the battery life that would also be useful.  I need to keep everything less than 2g (lighter is better).

My plan is to also have a temperature sensor and store temperature data on the Attiny. The main purpose I have for the transmitters would be to find the animals at the end of the study to retrieve the sensors rather than to track the animals so it would not need to be working continuously.

Possibly this is an obvious question and it would work fine, but it will be a lot of work so just wanted other opinions in case someone can see that it won't work or can suggest a simple and better way to increase the battery life.

Really appreciate any help, thanks!!


texts: Auto-charge 8.2V Lithum-ion battery pack

texts:
I am planning a device consisting of a load, a battery, and an external power source.

The idea is that the battery powers the system until the external power is plugged in -- then, the external source provides the power and charges the battery.

I am working with a 8.2V battery pack, and would like to add an auto charging circuit to this battery, such that it start charging when the battery has been discharged a certain amount, and stops charging when the battery is fully charged.

I would like to know what is a good way to accomplish this, and what voltage source/level I should be using to charge the battery safely.


texts: Why is this MAX6675 temp. sensor so wrong?

texts:
I recently bought this MAX6675 sensor with a K-type thermocouple, and I'm wondering what's wrong with it. I'm been testing it against a DS18B20 based sensor (metallic tip), and MAX6675 is giving me readings
way off the mark.

I tested it putting both sensors together against a hot plate and taking readings every 15 seconds. Plate start from room temperature. Previously, sensors were bring to start temp by immersing it in ice water.

Connections:

DS18B20

- Signal to Arduino Pin 8.
- Ground to Ground.
- Vcc to Vcc (plus a 4.7K resistor between Vcc and Ground).

MAX6675

- SCK to Arduino Pin 4.
- CS to Arduino Pin 5.
- SO to Arduino Pin 6.
- Vcc to Arduino Pin 3 (HIGH).
- Gnd to Arduino Pin 2 (LOW).

This is the result from a run test (temps in °C):

Basically, the greater the temp, the greater the difference between MAX6675 reading and "true" temp (as defined by DS18B20). In previous tests, when real temp reach 100°C, MAX6675 was giving ~150°C readings. This is not a offset or noise, but something else, almost exponential.

What is wrong here? Bad thermocouple? Throw it away and buy something else?


texts: protect standby lithium ion battery from continuous charge

texts:
The Amazon Echo Dot is a neat device and pretty portable, except that it doesn't have a battery and it takes a minute or so to reboot if you unplug it from one place and plug it in another.

I've used a li-ion powerbank pack attached to the Dot for a year now. Very convenient to be able to carry the Echo Dot to another room to continue listening to a podcast. But to do that, it has to remain plugged in to the charger full time. Recently I noticed that the rectangular package had popped apart. Apparently the Li-Ion cells swelled under continuous charge. Not confidence building.  So, what I really need is a rig where the Dot can be running on AC power, I plug in a battery before unplugging the AC supply, carry it to my destination, and then either plug into AC again or continue running on battery for as long as it lasts. And then I recharge the battery separately. I'm sure such a thing is possible electronically but I've never seen one. An OTG octopus might work but I'm not sure.

To be explicit, I think I need something that has a micro-USB output (which goes into the Dot) and two micro-usb inputs.  One input would be for the battery pack and the other for output from a wall wart.  And I need to be able to plug and unplug either one (though obviously not both) without resetting the Dot or shorting out the power supplies.


texts: Indexing a column of a Systemverilog array

texts:
x is defined as :
logic [ 0 : 1 ] [ 2 : 0 ] x ;

Is there a quick way (not a custom function) to access a column of x ?


texts:
I'm pretty new to PCB design, so my question may be obvious for some of you.
I am wiring the layout of an LCD screen on a PCB using KiCad. When I came to powering up, the datasheet of the AT070TN92 suggests applying DVDD voltage before AVDD. I know I can use voltage regulators to gain power.
The question is, how can I ensure one voltage is applied before another? How can I make sure of the delay between DVDD and AVDD?


texts:
I am trying to use on chip I2C on NXP P89LPC954 microcontroller(80C51 based) for voltage monitoring.

I have two voltage monitoring chips of same kind(same chip with same register address) connected to I2C pins of microcontroller.
Now in order to write to one of the chip how can i send address and data to that specific chip registers.What i mean is both are connected to the same pins of microcontroller(SDA,SCL).

Microcontroller used :NXP P89LPC954

Voltage monitor ic   :MAX6656

Interface            : I2C


texts: Problem in the output current of an PNP current mirror

texts:
I have a problem in the implementation of a current source, based on an OPAMP voltage-to-current converter followed by a PNP current mirror (see picture).
Indeed, the output currents are identical to the input current in R1 only when the supply of the mirror is 5 V. Unlike in the LTSpice simulation, in the physical circuit their values increase exponentially with the increase of the supply. The input current value is 2 mA. Is there a way to solve this problem? maybe by adding resistors between supply and emitters?


texts: Soft diode clipping for 'controlling' amplifier levels and avoiding harsh distortion

texts:
The title might be misleading/confusing. I'm building an amplifier with TDA2003 IC's which could be both suitable as a guitar amplifier and as a music amp.
 Where diodes come into this circuit?  As you might know most transistor based amplifiers clip really harshly and it's amplifiers way of telling you "stop asking more from me!".

The idea I have - putting soft clipping diodes (perhaps 1N4148?) before the input of the amp and to manipulate it in a way that it starts softly clipping just before the amp could say "little more and I will be angry".

What's the point of that?  You would start knowing when the amp starts to reach the peak of clean amplification and you would still get in comparison a nice more overdrive like tone rather than instant angry distortion.  For me this is great as my amplifier is going to be used for both guitar and music so in (my) theory it should sound quite great both at low and high levels of amplification for both guitar and music!

Though I've came across a problem - how do you manipulate the diodes so they start clipping only at specific input level?  Would it have to be resistors before diodes?  And would this affect music audio listening quality when the signal is supposedly clean (and soft clipping diodes are on vacation until input is higher)__?
P.S.  perhaps you know any great diodes that clip softly besides popular 1N4148?


texts: How can I protect an analog output from high voltage?

texts:
I have a DAC output from my STM32 microcontroller. The DAC output gives 0-3.3V and I want to protect it from high voltage backwards, e.g if I apply e.g 30V onto the DAC output by mistake.
Is this the correct way to do it? I have one Schottky diode that blocks up to 30V and one 3.3V Zener that makes sure that the voltage can only be at maximum 3.3V due to the leakage from the Schottky diode. The Schottky diode has a 0.2A limit but that's OK. DAC outputs cannot spit out more than 30mA.
What do you think of this solution?


texts: Avoiding solder mask in certain region in Altium PCB design

texts: I want to have a region in my PCB without solder mask while the other regions should have solder mask. I am not sure how do I do it in Altium? Is it by having a Solid (copper) Fill in the Top/Bottom Solder layer?


texts:
I have read that it is inadvisable to leave the reset pin on an MCU floating, also I would like to expose the pins of my ATtiny84 so that it can be programmed by an Arduino. Is the 10kΩ resistor in the below schematic the correct way to tie reset to ground, while still allowing the MCU to be programmed via ISP?

simulate this circuit – Schematic created using CircuitLab


texts: How to convert single precision floating point numbers in a file into their 32 bit representation in VHDL

texts:
Test data consists of single precision floating point numbers in a text file. These must be read into testbench and applied to a 32 bit std_logic_vector input port. The numbers can be read in as "real" type but how does one obtain their 32 bit representation to store in a std_logic_vector?

Floating point numbers consist of mantissa and exponent. Here the floating point number shall be reversed to get its actual representation inside the hardware and that will be stored in an std_logic_vector.

Here are a few numbers in the text file: -0.951835638,  -0.154052139,   0.007186272. I need to convert these into their 32 bit binary representation and store it into std_logic_vector. These numbers are originally floating point with 8 bit exponent and 23 bit mantissa. I want them to be binary represented in this way when I store them into the std_logic_vector.


texts: Feasibility of using "computer RAM" with a microcontroller project

texts:
How feasible is it that I could connect the pins of some garden variety "computer RAM" to a micro controller for use as external RAM?

Is there specific hardware used on computer motherboards that help interface the RAM with the rest of the system, or is it just as simple as finding timing/transaction information about the memory module and implementing/writing a driver somehow?


texts: Broken lock on flat cable connector, can it work without?

texts:
I tried to replace the camera unit on my Samsung SM-C101 phone. It is connected to the phone's motherboard with two flat cables, that fasten and un-fasten through a little switch in the connector.

You can see the two connectors in the following picture, I circled them in yellow.

You can see the little black switches on the left of the connectors. Unfortunately the two switches broke and the flat cables do not stay still. I can fix that with some tape, but my question is:

Without the two black flaps, does the cable make contact anyway? Or does it need to be pressed?

I'm asking this because the new replacement camera unit does not work. It pops in an out (it is a zoom lens) but then I get a "Camera error" message.

The main culprit are of course these connectors, I'd like to know more about how they work.

Thank you very much for your help.


texts: What will be small signal trans resistance gain of shown circuit?

texts:
Take beta = 99.

I analysed this circuit using first considering this circuit as feedback circuit with shunt-shunt type of feedback and then  did the same analysis considering that the circuit is a common emitter amplifier ; i.e. I pretended that I don't know  feedback circuits and followed the basic approach of nodal analysis followed in small signal analysis.

I got different results for small signal Voltage gain from both type of analysis. Obviously, the analysis without considering the network as feed back is correct, but I want to ask that how to realize that I should solve using basic approach neglecting feedback concepts.

I am having vibe that it has to do something with approximations taken while feedback analysis that

[Y12]A<<[Y12]B

[Y21]A>>[Y21]B

are not appropriately satisfied in below circuit. That is why I got different answers. Please clear up this concept.
My calculations for Voltage gain

For calculating trans resistance gain

Why I am getting different answers for trans resistance gain using different approach?


texts: Is it good to clear the state on 'posedge enable' in verilog

texts:
I am just getting started with verilog and I wanted to try to create a module which calculates whether a point in the Mandelbrot set diverges or not.  I am planing on using the Xilinx IP for 32 bit floating point math.  Bellow is the code I have so far which is far from complete.

What I want to do is when the enable wire is flipped from false to true I want to reset the state of all of my registers so the calculation can begin on the next clock cycle.  I was wondering if this is a good practice or not.  I was thinking the issue may be that when enable changes to true, but the always @(posedge clk && enable == 1) begin executes before the initialization is done.  Is there a better way to go about this?  Maybe I should have an internal enable register which is changed when the enable wire is triggered.

Also I am just wondering if the EE stack exchange is the best place for verilog questions?  I have been posting on stack overflow but these questions tend to not get much attention.

module mandelbrot(
    input [31:0] x,
    input [31:0] y,
    input clk,
    input enable,

    output reg [7:0] count,
    output done);

    reg [61:0] z;
    reg [61:0] zsq;
    reg [1:0] state;
    parameter SQUARING = 0;
    parameter COMPARING = 1;
    parameter ADDING = 2;

    reg valid_sq;
    reg done_sq;
    reg in_sq;

    reg valid_add;
    reg done_add;
    reg in_add;

    reg valid_lt;
    reg done_lt;
    reg in_lt;

    always @(posedge enable) begin
        z = {x, y};
        valid_sq <= 0;
        done_sq <= 0;
        in_sq <= 0;
        valid_add <= 0;
        done_add <= 0;
        in_add <= 0;
        valid_lt <= 0;
        done_lt <= 0;
        in_lt <= 0;
    end

    always @(posedge clk && enable == 1) begin
        case(state)
            SQUARING:

            COMPARING:
                state <= ADDING;
            ADDING:
                state <= SQUARING;
        endcase
    end

endmodule


texts: Benchtop power supplies: linear vs switching?

texts:
I'm looking into getting a decent benchtop power supply ($150-300) for hobby-level electronic design and testing. I don't want to modify or use a computer ATX supply because I want:

Adjustable voltage
Adjustable current
Low noise/ripple
Accuracy
1 or 2 voltage outputs
0-30VDC (AC not needed)
3-5A

As I look at various manufacturers' supplies, I am finding a few that seem like good choices, however I've encountered an aspect I am stumped on: Linear or switching?

I am planning primarily on small microcontroller projects, but I'd also like to do some audio and RF projects. I'm concerned a switching supply might have excess noise. Is this a valid concern, or are quality switching supplies more than adequate for clean battery-like power?

Also, should I assume that a supply which does not specify linear/switching on its datasheet is a switching type?


texts: Clarifications about GY-521 Module (Accelerometer and Gyroscope) for Arduino

texts:
I have some doubts about how to analyze data acquired through a gyroscope and accelerometer (GY 521, datasheet).

Precisely, let's consider this acquisition I have done when the module was still:

My questions are:

1) While I was reading the datasheet, I was not able to find any information about the reference (xyz) system. How are x, y, z axis physically oriented compared to the module?

2) Which is the meaning of negative values, if the reference axis are not specified? Does it mean maybe the verse of motion?

3) Is it correct that there are so high variations between two consecutive measures (in which the module is still)?


texts: I am replacing a wifi module for my smart tv. I have any never done this before and want to know if I need to solder the two components together or just use an adhesive like in the old module. The first two pictures are of the old wifi module while the last one shows that the pieces I need to attach.


texts: Designing 1-to-2 demultiplexing circuit with a custom truth table

texts:
I'm trying to build a circuit with following truth table with CMOS logic.

Pins are:

I and A are inputs
D0 and D1 are outputs
A is a line select GPIO pin (1 for D0, 0 forD1)
I is input level (when D0 is "selected" D1 level is set to 1 and vice versa)

I have figured out that D1 is simply "I or A" but D0 output is more difficult.

What is the general method of breaking down the problem in smaller pieces ?

I   A || D0  D1
1   1 ||  1   1
0   1 ||  0   1
1   0 ||  1   1
0   0 ||  1   0

EDIT: here's the solution. Any change to make it even simpler ?
circuit simulator link


texts:
I have this (run) capacitor with 4 terminals for a sewing machine motor. I have fixed some minor issues but now I realize I don't know how the wiring was before.
I don't find an explanation for the scheme on the back of it anywhere so I post the image here

Two terminals should connect the motor and the others two the pedal.
A front image, too, in case it helps:

I have not found anything about this model/type anywhere


texts: MCP1501 Voltage Reference has very noisy output

texts:
I want to use the MCP1501 precision voltage reference in an ADC circuit and have the issue that the reference produces a very noisy output. Much worse than an average LDO.

I have a VPP of 200mV when using the reference circuit shown in Figure 5-1 on page 19 of the Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/20005474C.pdf

How can this happen? Does the output have to be connected to a load?

Here is the measurement on the scope:


texts: Signal with little amplitude and offset in LTSpice

texts:
i have a problem trying to work with a signal whose amplitude is in nanovolts and has an offset of 1V. LTSpice doesn't plot the amplitude because is too small in comparation to the offset (the amplitude limit for plotting with the offset is 1 micro volt). Is there a way to make LTSpice more sensitive to these little amplitudes or force it to work with the signal? I need to amplify the signal but my amplifier needs the offset to work, and LTSpice does not amplify anything because it does not recognize the waveform because of the little amplitude it has.

Thank you


texts: Low noise amplification - Op Amps vs Transistor based amplifiers

texts: Whats the best amplification strategy to use for something requiring very low noise like an EEG (brain wave detecting)? Efficiency isn't really an issue. Op amps with high CMRR are expensive, and without a high CMRR there will be a lot of noise.. Is buying an expensive instrumentation amplifier (op amp) the way to go? Or would a cheap transistor based ie class A amplifier do just as well?


texts: How to simulate a d-flip flop counter/divider?

texts:
I would like to simulate a simple one-bit counter (or frequency divider) using the D-flip flop.

However, I don't want to use the abstracted D-flip flop above. Rather, I want to simulate this using primitive NOR/AND gates directly. I rigged up a D-flip flop based  on NOR Gates below.

The full simulation can be seen at this link: http://tinyurl.com/z6mae9c

However, I cannot connect the Q' output back into the "D" input without getting an error (endpoints circled in red below). Can anyone recommend how to fix this? Is this a limitation of the simulation framework? If so, what's a good package to simulate this on?


texts:
I just noticed this SSR that was for DCV instead of all the others that are normally for AC.

Although I can not find the datasheet for it, it does seem compatible with Arduino. eBay auction site and also here is where I found it.

However, I am just wanting to double check 2 things here:

My thoughts on how to go about wiring it:

I have 2 scenarios here. One that runs 12V out and another that does ground. Is this SSR capable of doing the 0vdc out since I am seeing the output is 5V-220V DC? I'm using the 0V DC to "push" a button (pushing = grounding it) so that the object it's connected to turns on or off.
I gather that when I send 5V DC to the SSR (via Digital Pin 1 or 2) it will open up the line for the 12V/0V to flow out the negative (-) side? Not sure if these are NO or NC? And as a side note, the diagram in the picture and the label on the SSR itself seems to be backwords? It says +/- and +/- while the diagram says -/+ and -/+?

Addition:

This image shows that they have some resisters in place:

Can anyone tell by those images above what type of resister they are using? Seems to me they are dropping the voltage by that on the arduino board side?


texts:
What is the purpose of the two 1N4148 diodes used in this circuit?

Regards

Edit:Source page of the circuit..

http://www.radanpro.com/Radan2400/Video/TV%20remote%20control%20blocker-jammer%20circuit%20diagram.htm


texts: Are neuromorphic computers considered digital computers?

texts:
This might be a pretty simple question, but I am wondering if neuromorphic computers using non Von Neumann architectures such as the IBM TrueNorth chip are still considered digital computers.

I have heard that some neuromorphic computers (don't remember which) use analog measurements rather than calculations when computing, but I believe that the interfaces are mostly digital. I am wondering if it affects the categorization of the class of computers.


texts: Safely wiring a 120v smoke detector externally

texts:
I am building a relay box that will cut power to an outlet if an attached 120V smoke alarm detects smoke.
The relay box itself will be a grounded metal electrical box hardwired to a 3 prong plug. It will present a 3-prong socket for the switched device. But I'm not sure what the safest way to connect to the smoke alarm is. Is standard gauge wire fine as long as it's rated for 120VAC? But in consumer devices, wire carrying mains voltage typically has a much beefier jacket, so this gives me pause. How should I splice the connection to the thin wires on the smoke alarm, wire nuts? It seems like a wire could come loose on the smoke alarm side, exposing a live wire.
   male 120VAC 3-prong plug
       |
+----------------+
| junction box   |
|                |
|switched        |
|120V outlet     |
+----------------+
  |            |
  |            | (Line, Neutral, Interconnect)
device       smoke alarm

Example relay module - Kidde SM120X that would be inside the junction box, using the interconnect to switch the device.


texts: Why is SPP20N60S5 rated for more power than STW26NM60N?

texts:
I'm wondering what could be the reason for SPP20N60S5 (PG-TO-220) to be rated for a maximam power of 208W and STW26NM60N (TO-247) only for 140W.
I compared both datasheets and in almost any attribute the STW26NM60N is superior to the SPP20N60S5.
Lets compare important attributes:

MODEL
ID_MAX
RDS_ON
Q_G
Q_GS
Rthj_case
CASE
P_TOT

STW26NM60N
20A
0.165
60nC
8.5nC
0.89°C/W
TO-247
140W

SPP20N60S5
20A
0.19
79nC
21nC
0.6°C/W
PG-TO-220
208W

What could be the reason for SPP20N60S5 rated for 1.5 times the maximum power?
Only information I could found on PG-TO220 is here Maybe the difference is another compound in the epoxy it self? That would be the only reason I could imagine for slightly better Rthj_case.


texts:
I am using a Polyolefin Adhesive-Lined heat-shrink tubing to water-proof wire joints.

The method works well but I need to measure if the seal is truly water-proof. The datasheet provides a test method:

  Prepare 3 test assemblies insulated with SCT-2 as follows:
  Construct a 2-wire to 2-wire inline splice in any suitable manner (crimped, soldered, twisted
  or welded). Splice an AWG 18 and an AWG 14 to an AWG 20 and AWG 14. Each wire
  shall be approximately 12 inches long. The wire insulation shall be cross-linked polyolefin
  and the conductor shall be bare copper. Shrink a 2-inch length of SCT-2 over the splice area
  with an appropriate heat gun. Apply heat until the SCT-2 is completely recovered on the
  splice and the adhesive liner flows at both ends. Allow the test assemblies to cool to room
  temperature and immerse them, except for the ends, in a 5% salt solution for 24 hours at
  room temperature. Apply 50 volts DC to the immersed specimens and measure the current
  leakage.

I do not understand how to measure the current leakage. I get it that the input current will be exactly equal to the output current if the seal is truly water-proof, but if the seal is not water-proof where else would the current flow anyway?


texts: Countdown to specific date and time (6 months away) and then count up

texts:
I am looking to build a device that would countdown to a specific date and time (approx 6 months away); countdwon in days:hours:minutes:seconds.
And when it reaches that date and time starts counting up in days:hours:minutes:seconds.
The device should fit in 10x60x40mm (display included). 60x40mm is loose and could be little bigger but 10mm thick is important.

edit (by Steven)
Greg said in comment that he wants it to be battery operated.


texts: StarRC extraction types vs process corners from foundry

texts:
When extract layout with extraction tools such as StarRC..., we have types of extraction such as RC, C types. From foundary such as TSMC, Samsung, they provide us with corners such as RCbest, RCworst, Cbest, Cmin...
My question is that what are the differences between them? If i choose to extract with C types (Cap only, isn't it), i still have corners like RCbest, RCworst (how resistance makes sense if i extract only Cap )for simulation. I am not clear about these two differences.
Please help me explain!


texts: Confused about phase angle of Network Function

texts:
When exactly are we supposed to make our phase angle \$180\$ or \$-180\$. For example if I had the following network function $$H(\omega) = \frac{-\omega_o^2}{\omega^2}$$

Why is the phase angle \$-180\$ as opposed to \$180\$?

Or if I had the following network function $$H(\omega) = \frac{-R_2}{R_1 + j\omega CR_1R_2}$$

The phase angle is supposedly $$180 - \tan^{-1}(\omega CR_2)$$

Why could it not be \$-180\$ instead?


texts: Micro-controller: External Interrupt " RBIE "

texts:
I'm working on a little project using micro controllers (PIC 16f84A) and got stuck at a point. I have 4 switches and those are the external interrupts now the idea is I don't understand how can I know which switch caused the interrupt to occur?

Say I have four switches SW1 , SW2 , SW3, SW4 now all those have a common external interrupt mode and flag RBIE and RBIF. If someone pushes the SW2 switch then I should do a function "2" how can I know that SW2 was the one pushes and not SW1 ?


texts: What does having complex conjugate zeros implies?

texts:
I am studying control systems, and I have found a system which has two complex conjugate zeros.

I know that if I had two complex conjugate poles in the system, this implies having some damping in the frequency response, but what does having complex conjugate zeros implies?

Moreover, I have found them in the RHP, so they have positive real part, what does this implies?

By plotting the frequency response of my system I have this:


texts: Help with PN512 basic PCB antenna design

texts:
I'm designing a small board that integrate a PN512 IC along with other components (MCU, etc). I need to build a proof-of-concept device for a presentation with the suit people and everything is ready but the PN512 antenna/matching circuit design. My guidelines for a PCB antenna are:

It must be single layer. (I've seen single layer designs with a 0 ohm resistor as a jumper over the traces)
It can't be more than 10x10cm or 4x4in.
I need it to successfully transmit data between the PN512 and an external NFC device, 5cm (2 in) or less range will be more than fine.
I own a 200MHz scope to play with (Sadly, no network analyzer).
My knowledge of the "black magic" behind this is very limited, but I'm learning as i go.

So my question is:

It is possible to build an antenna with the above requirements? Do you know of any (open) design available to get as starting point?

I've found many design guides for 2.4GHz antennas, but nothing helpful for the 13.56MHz range. Any help will be highly appreciated!


texts: Convert PDF schematic to any form of schematic files like .sch

texts:
I am new to electronics. I have a PDF schematic file of a power supply.
I wish to convert this PDF file to any form of file which can be imported in Simscape Electronics.
Is there any way to convert this PDF file to schematic file without redrawing it?
I do not need image background. I need to convert it to a schematic file which I can modify and test.


texts:
I am designing a circuit which may fail to start up. It has a power good output which is high when the supply is working. When the power good output goes low, the circuit has failed to start oscillating properly, and needs to be restarted. I thought about using a 555 timer but couldn't figure out how to make the output stay high when the input signal was low. Any ideas?

The circuit must do this because it fails to start under high current set points. It drives an LED. The idea is at higher currents the output folds back, but doesn't require an actual restart of the circuit to get it working again, and the fold-back mechanism makes the LED blink on and off.

Here's an image to show what I mean. Green shows the LED current. It has been set too high and the supply's overvoltage protection circuit kicks in to prevent more than 4.7V being applied across the LED (to prevent breakdown of the LED if in reverse.) The blue trace represents the power good output. During the oscillations the supply is outputting correctly, so it is high. It drops low after the oscillations stop. A short delay after it drops low, I need the supply to reset and try again - this would be accomplished by turning the supply controller IC on and off.


texts: Using UART's TX & RX for Separate Functinality

texts:
I am using PIC18F4520.
The project  requirement is to interface GSM module with uC as well as receive commands from PC via serial port.

to achieve this I have connected Microcontroller- TX to GSM module- RX, as GSM module is used just for sending SMS. It is working OK with this connection.(this connection is on TTL level.)

but i want to receive command from PC , so I have connected PC- TX to uC -RX (this connection is through MAX232).
when i connect PC-TX to uC-RX the serial terminal s/w (PC) shows garbage values on RX, and uC also receives garbage values (As I am not sending anything but still Receive interrupt routines gets called continuously ) . there is no issue in program.

but meanwhile the GSM module working fine.

Do i need to terminate the TX line?
I am using just 2 wire serial cable for connection to PC.

Thank You


texts: A book that talks of how computer hardware is designed

texts: There are many books aboout what CPU's pipelines do and etc., but I am unable to find a book that talks of how computer hardware is designed - technical stuff, like electrical engineering stuff. Can anyone recommend some book?


texts: What is a 50-ohm antenna? How would you make one?

texts: This is an intentionally very open ended question. What does it mean for an antenna to be a 50-ohm antenna at some  frequency? How do you make a 50-ohm antenna for say 433.92MHz? What are the options? What are the consequences of it being different from 50-ohms?


texts: Using a stepper motor for an electric bike

texts:
I'm going to design an electric bike using a BLDC motor.

According to my knowledge there are two types of BLDC motors: normal BLDC motors and stepper motors.

Can I use a large stepper motor for the ebike?


texts: Why is a BJT considered "current-controlled"?

texts: With BJTs, we can control base current using Vin (from diagram). Why do textbooks state that BJTs are current controlled when it's obvious that changing the voltage controls the current through the collector?


texts: What are the advantages of a shunt resistor vs. a hall effect sensor?

texts: I'm constructing a boost converter, and I need to measure both the input current and the output current. Currents range anywhere from 25A to 200A, depending on the model. My controller is referenced to the negative rail of the converter. I've been focusing on hall effect sensors, but it occurs to me that I could use shunt resistors in the negative leg instead. What are the advantages and disadvantages of each approach?


texts: AMS1117-3.3 outputs 4.4 V from a 5 V supply

texts:
[disclaimer - I am new in DIY and this is the first PCB I designed myself]
I designed a PCB for a very simple ESP8266 12-F + RGB LEDs project.
I assume that I am doing something fundamentally wrong because the voltage regulator is connected to a 5.1..5.4 V, 500 mA supply but outputs 4.4 V instead of 3.3 V.
Note that the AMS1117-3.3 regulator uses the tab as another VOUT.
Note also that only the power-supply, the capacitors, and the regulator are currently mounted to the board. The ESP and LEDs are not yet on the board.
For details check the schematics screenshots below:

Any hint/help is highly appreciated!
EDIT:
I am terribly sorry, just noticed that the actual design which was printed indeed was using the full-copper approach:

UPDATE:
In the meanwhile my ordered 22uF smd tantalum capacitors arrived and I did some experiments:

22 uF capacitor without resistor -> 4.34 V
22 uF capacitor + 330 ohm resistor -> 4.22 V
22 uF capacitor + 100 ohm resistor -> 4.00-4.01 V
22 uF capacitor + 10 ohm resistor -> 2.68 V

So my follow-up question here would be if this is expected output? And do I need to use one of the resistors if I want to connect the ESP now?


texts:
This may sound like a strange question, but its bothered me for a while:

I assume electric stoves (the ones with the coils that get red hot) work just by having a resistor that gets hot. If it's getting hot, then it must be using a lot of power so it would be pretty low resistance, but the heating element would still be higher resistance than the wires so the heating element is what gets hot. But to change the heat if the stove there must be a variable resistor, why does the variable resistor not get really hot when you lower the heat?

Am I really off about how all this works?


texts:
Voltage drop for red LED is around 1.7V, but in my experiment, which consist of a voltage supply connected to a 330ohm resistor and a red LED all in series, the min voltage supply needed for LED to light up is 1.7V? by using Ohm's law the current is 0 ? but the LED light up ?

(I'm supposed to find the min voltage (and current) needed to light up the LED)


texts:
We have to draw 3A in peak bursts, so I computed 55 mils wide for this amount of current. The footprint on this drawing is of a transistor, that has a small footprint. Would it be best to keep it this way or reduce the track width?

If track width reduction is necessary, please comment if successive reductions are necessary.


texts:
Does anyone know what this component with the package marking 63 and the "T" next to it is? Is it a Toshiba or NEC perhaps?
It resides on a small buffer PCB next to a 74AVC2T45 device.


texts: Why have both: BJT and FET transistors on IC output?

texts:
This is the structure of FAN3100 gate driver IC:

(taken from its datasheet)

As you can see - there are two ouput switches: CMOS and BJT.

Why they put them both?


texts:
Given an N-bit R2R DAC, with input voltages of e.g. 0-3.3 volts, what is the the best way (signal integrity and quality maintained) to attenuate its output voltage to a range e.g. 0-.7 volts for a VGA signal.

Is it as simple as using a voltage divider, or would something like an opamp be more appropriate?


texts: Measure/Access Information from small device through audio jack (mic)?

texts:
I've got a small device that I have not yet opened. It sends some unknown sequence of voltage and current through a medium for a few seconds thereby calulating and then displaying a result value on a display. During the measuring time it also displays some small waiting animation on the screen. I guess that one small chip will be handling all these activities.

Now I'm wondering how I could grap the result and import them into a smartphone through the audio jack. I want to loose the integrated display of the device and only use the smartphone screen. What would be the smartest way to go?

Grabing the display signal doesn't seem to be feasable because it are multiple digitally coded lines and not one signal with ampiltude. Could I maybe listen to the measuring signal through the audio line and then try to do my own reference measurements, or might this disport the actual measurement? Is there maybe some other way to grab this information to provide means of interoperability?

What voltage (& current?) can be measured my a mic in line and how must the signal be modulated? Some fixed frequency or can microphone electronics also analyse frequency?


texts:
I have found this circuit of a millivoltmeter, and it seems like something which as a hobbyist I can do it, and the range of the measurement is very suiting one of my projects, but I would like to attach it to an Arduino interfaced precise 24 bit ADC, so my question is:

How to replace the ammeter with a voltmeter in order to interface an ADC?
Is there some better replacement of the IC LF351 in the same circuit?
What diodes I shall use as the best option?


texts: How can I connect the MTCH6301 touch sensing controller to an Arduino?

texts:
I made this PCB (image below) and I connected all the copper area to the touch sensing controller (MTCH6301), but I don't know what to do now.

What do I need to connect the MTCH6301 to? I want to be able to connect this PCB to an Arduino.


texts: Hello I have a circuit here that turns on an led when the switch at the bottom opens up. My first problem is that I would like a NO push button that turns off the LED when it’s hit. But I would also like the light to stay on for let’s say 5 seconds after that push button is hit. That’s why I tried adding the capacitor at the top, I’m obviously way off on basic capacitance and need to do more research,  but any help you could give me would be appreciated


texts: Electric skateboard ESC and homemade battery pack

texts:
I am building an electric skateboard and it requires an 80A ESC and 22.2V Li-po battery to run.
I found a video where a guy connected a bunch of 18650 Lithium Ion cells in series to form an equivalent voltage supply. https://www.youtube.com/watch?v=1D90heZ8z4s
To my understanding, the amperage of the cells must match the amperage of the ESC. A standard cell is 3.7V 10A (/20A) so how does this work? Does the amperage of my battery matter?
Apologies and thanks in advance. I am new to this.
Cheers,


texts: Stepper Driver TMC5160 strange mosfet behaviour

texts:
So I made stepper driver PCB with the TMC5160 (datasheet) but I noticed something weird about about one of the motor outputs. Of the 4 motor outputs (A1, A2, B1 and B2) B2 always seems to have some kind of "ramp" in turning on (see images). My PCB has 2 TMC5160 gate drivers and both drivers show this behavior although not equally as bad. All mosfets are of the same type (AON7400A) and all have the same value gate resistor (15R). I measured other PCB's and the B2 output always shows the same "ramp thing" with varying degrees of severity.
Does anyone know what is happening here?
Here are some scope images (channel 1 = motor output, channel 2 = 24V supply).
In order they are:

Output B1 (driver 1)
Output B2 (driver 1)
Output A1 (driver 1)
Output A2 (driver 1)
Output B2 (driver 2)
Schematic of one of the mosfet h-bridges (with scope measurement points highlighted)


texts: Steady state current in circuit containing dependent source

texts: I was solving a question and got confused about steady state current in circuit (image), in solution it is given that steady state current across inductor will be zero as all the initial current of inductor dies out, but I wanted to know whether dependent  sources always acts as a resistor (absorb power) or it can also deliver power so that steady state current can become some finite value  also? If both conditions are possible then what factor determine steady state current in circuits(image)  like this?


texts:
This is a rather elementary question but I think my fundamentals are not clear on this. What is the voltage at the common node?

Firstly, I thought voltage was taken across something i.e it's taken with a reference to some other voltage. How can we say what is the voltage at the node? My professor claims that the voltage at that node will be Vcc since the negative of the battery Vee has zero voltage and the positive of Vcc is Vcc.

He also claims that voltage Vcc should be greater than Vee to keep the Emitter Base Junction in forward bias and Collector Base in Reverse Bias. Why is this?

I am also perplexed in other bjt configurations- Common Emmitter.

What is the voltage at the common node here and how do I know if they are properly biased in their active region?


texts: Is it possible to "hash" a circuit board?

texts:
I'll preface this by saying I'm a software engineer by trade and have very little EE knowledge.
In the software world, one can take all the bits that make up a file and generate a hash for a file. When the same hash algorithm is used, the hash of a file with identical contents is always the same.
I've always wondered whether or not something like this would be possible for physical circuit boards (not design files).
It seems to me that some combination of electrical/physical measurements ought to generate a unique identifier.

This identifier could be used to make sure the board wasn't tampered with.
One could independently verify the components of the board by reconstructing it and making sure the "hashes" match.

Is there any fundamental reason why something like this isn't possible? Is there any work being done in this area?


texts: Lattice MachXO2 EFB Timer/Counter timing specification missing

texts:
Searching through Lattice FPGA-DS-02056 (MachXO2 Family Data Sheet) and TN1205 (Using User Flash Memory and Hardened Control Functions in MachXO2 Devices), I couldn't find a detailed specification of the embedded Timer/Counter's tc_rstn active-low reset: is it a synchronous or asynchronous reset?
If synchronous:

What are the setup/hold times vs the Timer/Counter's tc_clki clock input?

If asynchronous:

What are its timing requirements?
Specifically, what is tc_rstn's minimum active time?

Also missing from Lattice TN1205 is the behaviour of the Timer/Counter's tc_oc output upon a Timer reset. Specifically in the Clear Timer on Compare Match Mode (the one I am using) with tc_oc in TOGGLE mode:

Does tc_oc change state upon a reset?
If yes, what is the propagation delay from tc_rstn to tc_oc (if asynchronous reset) or from tc_clki to tc_oc (if synchronous reset)?

Thanks for your help!


texts: What does "heavily decoupled voltage source" mean in this context?

texts:
Regarding the following paragraph:

  To measure the amount of input-referred noise, the input of the ADC is
  either grounded or connected to a heavily decoupled voltage source,
  and a large number of output samples are collected and plotted as a
  histogram (referred to as a grounded input histogram if the input is
  nominally at zero volts).

What is meant by "heavily decoupled voltage source"? Could you provide a circuit to illustrate it?


texts: Enhanced 16F PIC: How many instruction periods does automatic_context_save require?

texts:
I am about to do my first design with an enhanced 16F PIC microcontroller.  I have a question regarding automatic context save & restore that occurs when an Interrupt is triggered.

Specifically, how many instruction periods does an enhanced PIC16F microcontroller such as the PIC16F1782 require to perform the automatic context save when an interrupt is triggered?

Older 16F PICs without automatic context save require 2 instruction periods to jump to the Interrupt vector and an additional 2 instruction periods to return from Interrupt.  Context save within the ISR requires a minimum of 3 instruction periods to save W & Status and context restore when exiting the ISR requires a minimum of 4 instruction periods to restore Status & W.

The datasheet for an enhanced 16F PIC (PIC16F1782) says that all of the following registers are automatically saved in shadow registers when the Interrupt is triggered and restored when the Interrupt Return is executed:
• W register
• STATUS register (except for !TO and !PD)
• BSR register
• FSR registers
• PCLATH register

However, the datasheet doesn't state how much extra time (if any) is consumed by this context save and restore.  The closest thing I can find is in the Instruction Set Summary (Table 29-3 on page 344 of the PIC16F1782 datasheet - DS40001579E) which states that RETFIE requires 2 instruction periods (same as the older 16F PICs)..

I have learned the hard way that sometimes the Microchip data sheet isn't always complete.


texts: What type of  LED lights are needed for detecting retro-reflective markers for motion capture project?

texts:
I've a project in which I want to add 10-12 led lights around webcam's lens so that the camera can detect retro-reflective tape in it's viewing area.

How this process works is something like this. I'll power on the  red led lights while taking pictures of a human model. The red light of leds will make the captured frames' tapes put on human model light up very brightly(reflection of tapes will be at the same path of led light's emission-because the tape is retro-reflective) so I can separate the tape from other objects in the scene and find its 3d coordinate using c++ programming and image processing software.

I need advice in buying the led lights from http://www.digikey.com. Because I need very bright red led lights and also efficient(low voltage like 1.5 - 2volt and low amperage) what should I look for in the spec? Do I need to change the color of led lights(the tape reflects 50x more than normal white diffused surface)?

What is Millicandela rate?

How this rating help choosing the brightest led light?

The camera's vertical angle of view is 52 degrees and horizontal FOV is 75 degrees. So if I need to create a technically professional looking mocap camera what type of led lights do I need for this project?

If I capture the 2d images in a  brightly lit room will the led lights and my process(explained above) work with the camera? What wavelength of led light is important for this project? Should I broaden my spec for voltage and amperage?

Any other advice is welcome.


texts:
I am making a new design which I use a 4S 18650 batteries with total voltage of 14.8V

in my design I need to have 9V and 5V using 7809 and 7805 regulators

are these regulators going to overheat ?

here is a schematic of my design


texts: How to I determine/ interpret values of autoranging multimter

texts: I have an autoranging multimeter and many AA batteries.... how do I interpret the readings when deciding to keep or discard AA (1.5 volt) batteries?


texts: How to calculate thermal conductivity of potting compound around complex shape

texts:
I am currently evaluating the performance of various cooling strategies of a high-dissipation toroidal core inductor. The inductor specs:

20mm diameter core
9 turns (=very sparse), 16ga
5W core losses (max)
2W Joule losses (max)
High voltages may occur between heatsink and the conductors
Heatsink on one side of the inductor, coplanar with the core at about 1.5mm distance from the outside of the turns

I am currently evaluating cooling strategies for this relatively high power density component. One of these strategies is using thermally conductive potting compound. However, I am a bit lost. Can you help me with:

Evaluating whether this compound is the best I can get (for evaluation purposes - price is not terribly important)
Explaining how I would go about (roughly) calculating the temperature drop over the potting compound if I use this compound to space-fill between the inductor and an aluminum heatsink

The shape is obviously quite irregular, so it's not immediately obvious to me how to attack this calculation. Especially as the core is the main source of heat here.


texts:
When I learnt how to do a Nyquist plot I was taught a really long-winded method that I don't understand to this day. I realised by myself that if you are given a system like below where \$s=j\omega\$ $$\frac{s+1}{s+10}$$ you can just replace \$s\$ with \$j\omega\$ and put in several values of \$\omega\$ and plot these outputs on the real-imaginary axis.

Is there a problem doing it this way because I cannot understand why it would not be taught like this if it is this easy?

EDIT: added image below.


texts: How can I create a DC-DC voltage multiplier

texts: I want to take the 5V output from a USB port and make it 12V, so that I can run a cooling fan which is 12V. Is there any circuit I can make at home myself? If the output voltage is not exactly 12V, it can be at least 11V so the fan can run smoothly.


texts: How to switch between 2 LEDs using a powered momentary DPDTswitch

texts:
Problem http://www.webamplayer.com/dpdt.jpg

I need a visual indication which way the DPDT has been thrown. Should I use a relay?


texts: Why is my fluorescent tube orange on one side, white on the other and dark in the middle?

texts:
I have a ~60 cm fluorescent tube light that is failing. ~10 cm on one end glows orange, ~10 cm on the other end glows blue-white (normal fluorescent light color) and the middle 40 cm is dark.

Question: From an electrical point of view what exactly is going on such that this particular graded pattern of three colors is produced?

There seems to be a "starter" just behind the tube, near the "orange" end.


texts:
I am using STM33F in my application, it has 12 Bit DAC.

For one of the audio codec module in same application, stereo DAC with inbuilt amp needs to be implemented (IC TLV320DAC3100). Above codec will store voice in digital format and will play audio and has built-in DAC.

So, can we use host controller in-built DAC instead CODEC DAC? Is there any pros/cons/constraints while using in-built controller DAC?

Thank you.


texts: Control Dielectric vs. Controlled Impedance

texts:
Can you tell me what the differences are between Controlled Dielectric and Controlled Impedance.  Also what is a TDR report?

I'd appreciate it.


texts: Possible causes of dead cyclone IV on custom board

texts:
i designed and soldered my first fpga board using cyclone IV in the 144 eqfp package. First of all, i made following mistakes:

I am using 3.3V VCCIO for all IO banks. I misread the handbook and
connected TMS and TDI pins on the 3.3V VCC instead of 2.5V VCCA.
After realising this, i corrected it but it might be too late. Would
this be enaugh, to fry the JTAG?
After soldering the chip in place, i failed to notice in time there
are about two to five solder bridges between pins. Some of them
shorted my 3.3V VCC. After i realized this, i reworked the chip and
triple checked for any bridges. There are not any.
Because of the problems mentioned above, i had to solder and
desolder the chip twice. I was using hot air station. I tried to
controll the temperature as well as i could (with thermocoupple
right on top of the chip) but i did it by hand. Could it be damaged
by the heat?

When i connect the board to the USB blaster, quartus says that it could not initiate JTAG chain, because no devices were found. I tried debugging the jtag using oscilloscope, but since this is my first time trying to do it, i do not know what exactly to look for. I noticed the following:

When using JTAG debugger and setting how many clock pusles to send,
clock signal looked quite weird. If i sent less than 8 pulses, the
scope showed quite nice square wave. But when setting the clock to
send more pulses, the signal became weird. There were few nice
pulses as before and then there were random bursts of pulses of
about 6x the frequency of the original ones. At first i thought they
were just noise, but they were perfectly uniform. Almost seemed like
the programmer would try to communicate on different frequencies. I
do know if this is normal behavior of JTAG or not.
The TDO pin was staying high all the time. Which i assume is a sign
of broken jtag interface in fpga.
Other pins were showing some data, but i do not know enough about
the protocol to say, if it was correct.

Every VCCIO is connected to the 3.3V, every VCCA to 2.5V and every VCORE is connected to the 1.2V. Coud the problem be, that VCCIO of the bank where JTAG resides is 3.3v?

I am sorry if i forgot something or sound too stupid. This is my first fpga project so please be kind. :-)
Thank you in advance for all your replies!


texts: Hardware and software to program AT89S52 chips with linux

texts:
Seeing that the ATMEL AT89S52 chips are so cheap (8 usd for 5 with free shipping from ebay!), are supposed to have a simple architecture and a lot of documentation available online, I would like to use them to learn microcontrollers at a lower level than the Arduino.

I have already learned how to compile simple programs with sdcc and convert the resulting ihx file to hex with packihx, ready to be loaded into the chip.

I don't understand what hardware and software is needed to transfer the file from my laptop via a usb port. From what I've read avrdude doesn't work for these chips, what should I use instead? Also, what hardware should I buy to do the programming?

Can someone provide a simple guide for a beginner?

Thanks

EDIT: If I understand correctly, the circuit provided by Sandun only converts the RS-232 voltages down to 5V. If this is correct, and since I'll be using a USB port instead of a serial one, can I just use a USB - serial cable which outputs 5V like this one? Or am I missing something?


texts: Multiplexer CD4067 bug:signal appears in unselected channels

texts:
I connected a multiplexer CD4067 with arduino. I will select ch0-ch15 in turn and pass the selected channel to A0 on arduino to do AD Convert.

Then I only connected ch0 to 5V on arduino and selected all channels in turn to do a test. The result shows that when ch1-ch15 is selected, some of those channels will have a output around 5V and those "wrong channels" are fixed if you choose a fixed input channel. However when I connected a 1kΩ resistor between the output of CD4067 and the GND. Those unselected channels' voltage will be 0. And the voltage of ch0 will be around 4.2v. (I checked the connection and code which are correct.)

So after this, I changed the analog input to a piezoelectric film's signal. A similar problem exists. And I tried several kinds of resistors(max at 4MΩ), but the problem still exists.

I have no ideal about why this happened? And I am a little bit confused about some flaws about the CMOS. What is the possible solution?


texts: How to decrease nrf24l01 transceiver range?

texts:
I've just got my Nrf24l01 but then I found out that the working signal range for the module is 100m and above. Our real intention for the module is to let the nrf24l01(Receiver) out of range for about 5m in order to activate the alarm.

The purpose of our project is for anti-theft alarm which sounds the alarm if the module is out of range. We only need a short distance in order for the alarm to work since our research project is only for personal use.

We have an idea which we want to clarify if it is possible, it works by having the (receiver) to reach a fixed distance value in the coding of the arduino and when the (receiver) goes beyond that value, it will activate the alarm or beep. We want to ask if our idea is possible and if yes, can you help us how to code the arduino?.

I don't have any background in making a code for arduino but I know how to program an arduino using a ready-made code from the internet.


texts: How are the original signal and the AM signal related?

texts:
Use the TIMS “Variable DC” module to generate a 1V DC signal.
Use the “Adder” module to add this DC signal to the message
signal generated in task 1 (this will produce the [1 + K_a m(t)] part
of the AM signal).
Use a “Multiplier” module to multiply this with the carrier signal
c(t) generated in task 2.
You will now obtain the full DSB AM signal:

Display the time-domain of this signal as well as its spectrum on
LabVIEW.

Question
- Compare the envelope of this signal with the original
message signal, m(t) (You can display both the original
signal and the AM signal on the oscilloscope to accurately
compare them), how do they relate to each other?

Following picture are the result for this exercise but I am not exactly sure how to answer the question above "how do they relate to each other". Could you please explain me or give me any hint to start.

Thank you! Appreciate it!


texts: PS/2 keyboard with RS232 (DB9) workstation port

texts:
I'm currently awaiting for dispatch/delivery of a 1995 PS/2 Model M keyboard w/attached flat cable but a missing PS/2 plug
It seems those flat cables were not very sturdy.
(Yes, I checked the model number, it's PS/2).
Once cleaned up and checked out, my guess is the two easiest/least $$$ choices would be:

replace the original cable with a new one and use an active PS/2 -> USB converter.
crack open the above converter, hard wire it to the existing controller inside the keyboard case and wire in a nice USB cable with or without a socket.

But while looking through the collection of things I have stubbornly refused to throw away every year, I came across two things which at different times held permanent residence in my sack along with the rest of my gear:

a PS/2 to serial adaptor
I think it was original issue with the early Microsoft Serial Mouse 2.0 which had a PS/2 plug.

a USB Prolific PL2303 Serial Port board (invaluable)
Eventually cannibalised from it's original junction box and hard wired into my Palm III's sync base so as to make it USB instead of serial.

Since my Sun Ultra 24 workstation has an on-board RS232 which at some time in the past I enabled in BIOS and properly set up to use my serial data-logging hardware ...
~$ sudo dmesg | grep -i tty
--- snip ---
[1.821872] 00:02: ttyS1 at I/O 0x2f8 (irq = 3, base_baud = 115200) is a 16550A
--- snip ---
~$

... and the PS/2 -> DB9 adaptor has this pinout:
https://i.stack.imgur.com/t12O8.gif
Would it be possible to wire the PS/2 Model M with a DB9 plug and directly use my workstation's serial port, like it was possible with the PS/2 mouse?
ie: I'd avoid converting PS/2 to USB and solve the current draw issue some PS/2 keyboards have and free a USB port.
Software wise, it would be (?) a question of loading the now blacklisted PS/2 module in my Linux Devuan installation.
I'd appreciate your input.


texts: How to add part in eagle board that doesn't have "pad" but only holes?

texts:
I would like to add this part https://fr.rs-online.com/web/p/guides-de-lumieres-led/8796223/ on my eagle board.

I did the schematic (just to be sure it's in the project) and the "footprint" of the component.

My component has no pads only holes.

The problem is, I don't see it in my board design ...

Any idea to solve this ?

there is my symbol

there is my device :

there is my component footprint :

there is the library :


texts: increasing output voltage of a schmitt trigger op amp

texts: I have the Schmitt trigger circuit below that I read the output as 1.6V for the logic High. I wonder how can I increase the output voltage of the comparator below without changing the threshold of the Schmitt trigger?


texts: Is it possible to create an HDMI input adapter for android?

texts: Would it be possible to stream a video signal into an android device? I understand that the HDMI port it's self is not designed to take input, so I was thinking that the data could be streamed via the USB port. I know that the Apple hardware prohibits this (apple made this decision for some reason) but would it be feasible on android?


texts: I have a question about RSSI and EIRP. When I bring my smartphone very near my antenna wifi router (+20 dBm EIRP) the analyzer wifi application shows me an RSSI level about -20 to -25 dBm (a negative value). I don't understand this value! If I have +20 dBm EIRP (a positive value), why do I get -20 dBm when I bring my phone close to the router antenna? Why don't I get a value of +20dBm?


texts: Strange Behaviour of Lipo Battery ESR during charging

texts:
I performed three charge tests on a single cell 190mAh Li-Po battery with Keithley Battery Simulator instrument. Charging started at 3V and stopped at 4.20V in all tests.

After completing the three charge tests, I plotted the LiPo Voltage and ESR results and the ESR curves came out a little strange.

In the ESR graph (2nd graph), the blue ESR curve (first charge of LiPo) suddenly drops (SOC: 80%) and I cannot explain why this happened. The other two curves in the same graph have a smoother curve.

I cannot explain this sudden change in ESR in the first charge test (blue curve at SOC:80%)
I cannot explain the difference  between the first and the two following ESR test curves, since all three tests have been performed on the same battery

I searched for articles regarding Lipo ESR curves during charging but I have not found something.

If any ideas, please let me know.

Thank you.


texts: Am I going to encounter grounding issues with this PCB design?

texts:
This is my first time designing a PCB, and because it is part of a project at uni I have the intention of manufacturing it afterwards.  The circuit itself is a voltage-controlled oscillator designed by Ray Wilson MFOS:

Page 1: http://www.musicfromouterspace.com/analogsynth_new/VCO20120618REV0/pdf/vco20120615wsoic_page_1_assembly.pdf

Page 2: http://www.musicfromouterspace.com/analogsynth_new/VCO20120618REV0/pdf/vco20120615wsoic_page_2_assembly.pdf

The website is full of great info and resources, including the PCB layout that he himself used.  To speed the process of my design up I have mimicked his assembly layout using the PCB design tool that comes with TINA, but through differences of software, there are differences in the final results.

This may be a silly question, but my concern comes from the the grounding issues that may (or may not) arise.  On Ray's PCB there is a ground pin which I imagine is the bridge between the power supply and ground plane?:

And on my PCB i've used two pin headers, so there is effectively two ground pins, and am hesitant in how to connect ground properly from my power supply to the PCB using this particular set up:

The PCB started as two layer and I've added a ground and power plane, but how do I ensure that ground is connected properly at the VS1 and VS2 power supply headers after manufacture? Would I short the two ground pins and proceed to hook up the power supply, or use banana jacks to to hook both ground pins up accordingly?
I apologize for this rookie question, and if any more info is needed let me know! Here's an un-routed 3D view of my PCB design (ground pins of power supply headers circled in blue):


texts: How do I use an ATTiny board with right angled pins on a breadboard?

texts:
I created a project on an Uno as a proof of concept and now have reduced the code and squeezed it onto an ATTiny.

Before I transfer it all to a PCB I want to get it going on a solderless breadboard to make sure everything is still working (I don't quite trust my soldering :P ) and also optimise the layout.

The issue is that an ATTiny has pins at right angles to each other,

so no matter which way it is turned, a row of pins will be along a strip of electrically connected holes on the breadboard.

How do I get around this?


texts:
I want to know the numbers needed to build a capacitor bank to sustain a load of 36 V, 1500 W up to 5 - 10 minutes at time before needing recharge. I have four 10,000 μF, 40 V caps connected in parallel to a 12 - 36 V booster with a 36 V, 1500 W load connect to the other end of the cap bank.

Ok, thank you all for your input, let me add some more details. The Project is being powered by a 12 V car battery, the battery is powering a 12V DC motor turning a Self Exciting 12 V, 96 A alternator, the alternator is powering a 12 V to 36 V booster at 30 A and in turn charging the CAP bank and powering the 36 V, 1500 W load, while also keeping the battery charged, at IDLE the load is drawing 100 W.
OK, with the comments so far , i need to give more details again.
The battery is only powering the 12 V motor, cooling fnas and power monitors.
The alternator is supplying power to a separate set of power rails for the 12 V to 36 V booster from the booster to the cap bank and then to the 36 V 1500 W load, my thought was to have the cap bank as a buffer between the alternator and actual load device. A seperate 12 V mini charger will also take power from the alt and send it back to the battery to help keep it charged.
The motor driving the alt is 400 mA, 12 v, 3500 rpm with no load, the cooling fans are 120 mm computer fans so the draw from them is also minor, like a car the battery is basically only for starting the system while the alt is providing all the main power and returning some to the battery, NOT perpetual motion.
Does all this sound feasible and is there anything else I might need, like high-wattage balancing resistors and such?
What else do I need to know?


texts:
My electronics teacher asked me the other day to research the SAA 1027 to drive stepper motors however whats happened to them? In some newer textbooks they talk about using a PIC and then using a ULN2803 to drive it. Is this the new way as SAA 1027 are now obsolete?
Thanks in Advance,
Dean


texts: How to get the longest one's sequence in verilog

texts:
I have some problems with a question that ask me to get  the number of one's in the longest one's sequence in a 16 bit input using a 5 bit number in verilog. For example
(0111011111010101 = 00101 the answer is five duo to the sequence in the middle)
(1111111111111111 = 100000) I would like to know how to do it using both combinational and sequential circuits.


texts: Shortening the coax on UHF CB antenna caused SWR to get worse, why?

texts:
I shortened the coax cable on my car's 477MHz CB antenna because the braid was frayed at the transciever connector end, and a metre or so of spare coax was coiled up behind the dash. I thought if I cut the coax shorter, I would remove a little cable loss.

I measured SWR with a meter before and after: Before was 1.3:1, after 1.7:1. This seems quite a bit worse. I don't know how much this will affect performance.

I think I assembled the new connector pretty well, good solder joints to centre and braid.

Could my antenna setup be sensitive to the length of the coax? I have not heard of tuned lengths but my understanding of antenna and feeds is limited.

My vehicle's antenna is mounted at the front, it has a short solid base tube with a standard threaded mount onto which I fitted a 60cm 4.5dBi whip (the original antenna was missing). I don't know exactly what the antenna mount is but it looks similar to this one.

I'd like to understand what has happened, if I have significantly affected the performance of my antenna system, and how I might be able to fix it if so (splice the cut part of the coax back on?)


texts:
I'm trying to create a circuit that will pulse out (short pulse) whenever it passes a certain threshold going upwards and another one to detect going downwards. I was thinking of using delay to achieve this... but I dont know how to really go about it.

Any help would be appreciated, thanks in advance!


texts: A protecting circuit using GPIO of the BeagleBone (Black or Green)

texts:
I'm really trying to develop a cape since I need to use 7-8 GPIO-Pins of my BBB Green and Black as Output.
I'm too afraid to destroy the board somehow, so I was thinking to implement a solution which let me operate my board under safety condition without frying anything.

After reading over the internet I came up with the following solutions:

Here I would use a phototransistor such in the following schematic:

It is a light modification of this circuit: Raspberry Pi GPIO

the pros are that I don't need to care about the initial voltage state of the GPIO pins after booting the board. The BBB-SRM cleary states that no pin should be driven at boot, otherwise it can destroy the board.
Another pro is that I can get a non inverting signal at the emitter of the transistor (maybe I should put another resistor to reduce the current in the collector).
The only contra is that I should place and sold many resistors (at least 8) for my circuit. With this schematic I want to drive some circuits which are connected to the BBB.

the other one is simply to use such a non inverting transceiver like the following 74HCT245
In this case I would connect the single GPIO of the BBB directly, without any resistor, to the input of the device.
The pros are that I don't need any resistor and can connect the gpio directly

I would realize the first schematic because I'm really not sure whether the second one right is or not. If you think that the second one better or the most used is, could you please tell me why? I really want to learn and understand in this process and not just sitting there and doing passively circuit from the net.


texts:
When doing rtl design, mux is always used to select the input of a block/module, for example:

input [135:0] dataA, dataB;
assign FIFO_DATAIN=(sl)?dataA:dataB;
myfifo xxx(.(FIFO_DATAIN)
         .... );

Since the input data is 136 bits wide, this may lead to timing violations and requires a lot of resources after synthesis. Would it be better to use the "case" or "if else"? If not, is there a better way?
Thanks in advance


texts: Designing flyback converter - Current ripple and turns ratio

texts:
This would be a long question, I apologize in advance.

In the process of learning about flyback I've calculated same LT8302-based converter using five methods. Four from generic (as in: not related to any specific chip) application notes and guides, one straight from LT8302 datasheet primer.

All five produced different results. :( Generic methods were at least close (Lp 2.7~4.3uH) but the fifth was way out of line (Lp 23.4uH). Here is heavily simplified description of generic methods:

Calculate input power Pin from output requirements.
Either choose turn ratio proportional to voltages and calculate D from there or set D to 50% and calculate turn ratio from it. In either case D <= 0.5 and Nps is about 1:5.
Arbitrary choose current ripple factor Kr within 0.25~0.5.
Either directly calculate Lp from D, Kr, Pin and Vin(min) or first calculate average current from D and swing from Kr and then get Lp from those. In both cases Fsw assumed to be max possible and the results are essentially the same.

Every time I end up with Isw going over max rated current at Vin = min, and with Fsw going above maximum possible at Vin = max. So, I have to loop back and increase Lp until Isw gets into acceptable range (at about 5uH). As I understand, this decreases Kr well under 0.25.

Now, the method in LT8302 datasheet goes in opposite direction:

Ignore actual power requirements and go straight with Vsw(max) - safety margin.
Calculate Nps from that, which gives something like 1:1.3
Calculate D from above, which produces 0.8~0.89 (?!)
Calculate Lp from above using Toff(min) and Isw(min); result is 24uH (?!)

Surprisingly, the end result is that Isw stays under max in all Vin range, Fsw is around half of max FQ, and Pout is comfortably above required at any Vin. Although Kr is higher this time at 0.5~0.9.

I've been reading the book by Pressman and Billings (which was an eye opener BTW, "flyback transformer is not a transformer, it is inductor with multiple coils" 8O ). From there and other sources Dmax must stay under 0.5 to avoid oscillations. Looks like LT8302 makers do not worry about this at all.

Question: Which way to follow? (Obviously) Also, is Kr < 0.25 a bad thing?

List of documents used for calculations:
Analysis and Design of Multioutput Flyback Converter
Fairchild AN-4137
National Semiconductor AN-1055
Texas Instruments U-165
LT8302 datasheet

Update:

Here are couple calculations using "generic" methods. Both had Ipeak over max, so I had to reduce Kf to 0.2 to adjust.

And here are calculations based on LT8302 datasheet:


texts: Can a simple voltage divider circuit be used to accurately measure voltage?

texts:
I have a discharger circuit that I intend to hook up to a 3V battery. Total resistance of the circuit (depending on how fast I intend to discharge it) will vary from 0.04 to 0.01 Ohms (that's 75A and 450A respectively).

Can I hook up a simple voltage divider circuit in parallel to measure the 'health' of the battery? (Diagram below) Or will I run into some trouble?

Thanks,

Julia


texts: How to stop plastic granules sticking to the iron wall of their silo?

texts:
In our factory, we have some large (8 meters tall and 3 meters in diameters) iron silos for storing the plastic compounding material. Every time the silos are getting unloaded from the granules, the plastic powders stick to the inner metal layer due to the static electricity, so that the operator needs to knock on the wall severely in order to make them fall. I want to know:

1- How can I instantly make this static load discharged and get rid of this problem (Right now, the resistance value between the earth system and Null is almost 0.03 Ohm)
I would appreciate if you mention the standards and the detailed answers.

2- How can I measure the quality of the grounding system and what would be the standard range of this value?


texts:
I am working on a small touchscreen extension to implement into a robot (show debug, command some basic functions, show points on a map where the robot has to go, etc...).
Microcontrollers used are Cortex M3.

I am pretty new to the world of touchscreens and I see there are different types and I very don't know how to choose them, and on which criterion.
Astonishing colours or resolution aren't needed, just need something reliable and handy.
A size of about 5", 4:3 format should be great I think, but I will happily look at any suggestion.

Can you help me to choose, tell me where to buy, which price, indicate some references, tips ?
Do you also have some advices about how to interface it ?

Thanks a lot for your help,
Ryl


texts:
simulate this circuit – Schematic created using CircuitLab

The diagram above, the voltage sources are equal and wired parallel, they would increase the current(2x) flow to the load(R), but what about this case:

simulate this circuit

Are the two voltage sources in series now?


texts:
Would it be possible to have two microphones (which simply output a varying voltage between two terminals) connected to an audio jack (i.e. the standard laptop 3.5mm mic jack) and reproduce the sound picked up by both of them?

That is, one would have something like this:

simulate this circuit – Schematic created using CircuitLab


texts: modify 700VA UPS to power 65Watt Laptop Adapter for hours instead of minutes

texts:
I have 700VA UPS which I had bought in 2009 to power my Desktop Computer.It can power desktop(17" CRT monitor,CPU cabinet ) for 5-6 minutes.It has 7Ah battery(only 1), charging and inverting circuit and a transformer inside. Now I want to modify it to power my Laptop Adapter whose specifications are:

100-240V~1.8A 50-60Hz
20V-3.25A
65W

The problem is, it only last for 15 minutes. Since the load is only 65 watt, I had expected hours instead of minutes.

So, what should I do to make it last for hours??

I searched for this on google and went through several sites and found some things regarding UPS:

UPS transformer is designed to power high power device(generally 400-500Watt) for short time(5-6minutes). At longer use , it may burn.

So, if I change the transformer inside with lower capacity trasformer( 100Watt), will I get backup for long time(1-2hours). Also, I have cooling fan from desktop CPU cabinet which I can use to cool the tranformer.

Please suggest me ways to modify it.( If you are wondering why I need UPS for Laptop, here in Nepal we have Load Shedding for 11 hours each day and Laptop battery last only for 2.30-3hrs and if I am able to modify a UPS(lying around) for 1-2hrs, it would be great!!)


texts: I have a DAC that can provide voltages between 0-2.5 V and I need a -12.5 - +12.5 sine wave. I am not too steady on the circuit calculations. Would it be possible to amplify by 10 and set the positive input on the op amp to a 1.25 V ref? Like I have drawn in the picture. Or do i perhaps have to do it in two steps?


texts: triangle symbol in xilinx schematic view

texts:
I'm working on a project on spartan 6 using xilinx ISE 14.7. When I opened a schematic view, I cannot recognize the red triangle between those connections, which I think should not be an predefined block such as buffer. Is that an amplifier? If it's true, why it put in an opposite way? I'm new to fpga, thanks a lot for any help.

when I check the signals it shows two IOCLK as output pin and the others as input pin.


texts:
I'm looking for a "circuit swapper"; basically I need to change the voltage reference on "out1" and "out2". I have an input signal that changes periodically, so i.e. input = 0, out1 = 5V, out2 = 0V; input = 1, out1 = 0V, out2 = 5V. I'm worried about the transition between the swap..
hope the question is enough clear.
Thanks


texts:
I am using PIC18f microcontroller. I have to write a 16 bit integer variables (2 bytes) which was cast into two character variable i.e to write each byte in a consecutive adrressess of EEPROM. By first I have to write a upper byte(8bit data) in the EEPROM. I am unable to get the higher 8 bit of the integer variable by the following code (where I  am able to write the lower eight bit of the integer variable ). My code is

void int_EEPROM_putc(unsigned char address, unsigned char data);
unsigned char int_EEPROM_getc(unsigned char address);
unsigned char c;
unsigned int d;
unsigned char* e;
unsigned char f;

void main()
{
d=0xffff;
e=(unsigned char*)&d;
//f=*e
f=*(e+1);
int_EEPROM_putc(0x02,f);
delay_ms(100);
c=int_EEPROM_getc(0x02);
while(true)
{
    if(c==255)
    {
    PORTB=~PORTB;
    }
    else
    {
    PORTB=0xff;
    }
}


texts: FCC, ROHS and CE certification and compliance

texts:
I have design a PCB which has Stepper driver, micro-controller, 204JHD display, MOSFETS for driving fans and TRIACS for driving heaters.There is not RF components on the PCB.

What are the criterias for makiing the PCB compliance with FCC, CE and ROHS ?
Are there any specific guidelines or rules for which i must follow to make my PCB compliance with FCC, CE and ROHS ?

Where to get the reading materials for the guidelines or rules, if any ?

Do i have to go to any institution or lab to make my PCB compliance with FCC, CE and ROHS ?


texts: What sets the resolution of an analog resistive sensor?

texts:
When I read about film or silicon strain gauges their data-sheets mentions about their resolution.

But in analog world what sets the resolution? For example if you vary a potentiometer the output voltage changes accordingly so one can say there is relation between the rotation and the output voltage which would be a continous function not quantized.

Can you give an example which would explain the resolution concept for strain-gauge?


texts: Why doesn’t the comparator output go near the power supply voltage?

texts:
I had this circuit

And the output voltage wasn’t the same as the supply voltage.
I wondered that the reason was because the datasheet of the 741C says that the output shouldn’t be larger than the supply voltage. But, I wasn’t sure if this is the right reasoning?

The output voltage was between 9V and -12V depending on the potentiometer


texts:
I am currently constructing a laser microphone using 5mW red laser pointer source based on the idea below, not directly output to a speakers or headphones, but the signals must be fed into computer for further analysis.

http://www.lucidscience.com/pro-laser%20spy%20device-11.aspx

I am not satisfied with the detection area being too small and I have a 1V solar cell by now since it has been suggested that solar cell could be another choice as laser detector too. I just take in the raw output from the solar cell and fed into laptop using a 3.5mm aux audio cable.

Large Active Area phototransistors? And can solar cells be a replacement

The problem I am currently facing is the high noise content and 50Hz harmonics spikes when I check with the spectrum of recorded audio (sometimes it working really well as clear audio can be heard)but I am thinking of better and much more robust alternatives for my setup.

Photodiodes has come into my mind but I saw that they are not suitable in daylight conditions. I would have to use optical lens to concentrate the laser beam onto the photodiode surface.

So my question is
If I am going to use solar cell as laser detector, what can I do to improve the responsivity and reduce the inherent noise?
OR
If I am going to use photodiode as main detector, what kind of photodiode which has fast responsivity, optical setup should I use, and any other possible issues I should take care of?

Thanks.

P/S :  I do aware of the 50Hz noise may come from powerline interference but it still exists even it does not connected to AC power sources. I also make sure I turned off the lights and perform recording at dark environment.
I did use high pass passive filters consists of resistors and capacitors which have cutoff at 92Hz. The effect is not really that good but at least it can attenuate the 50Hz noise.

The entire setup (currently not functioning)

Solar Cell used here

Noise Spectrum of just pure recording without any light sources shines on the solar cell

Ok it has been a month but I here to say that not be able to recover the audio signals from modulated laser beam. The laser beam itself is modulated, but even with offline processing using the bandpass filter, I could not obtain any results after demodulation.


texts: Do I have a short? Why is my breadboard burning?

texts:
First, yes I've unplugged the power source.

Second, I'm an electronics newbie so please be patient.

Finally, I'm working on a project and I think I may have a short. But I'm not understanding why.

The project: An LED strip with a dimmer.

The problem: My breadboard was burnt and slightly melted along the positive and ground lines closest to the power source. Here is what the breadboard looks like:

Here is a diagram I wrote up (hope I got that right; it's my first attempt).

LED = Neopixel RGBW 60 pixels/meter 1m strip
MC = Arduino Pro Mini 3.3V
AC = 120 V AC wall outlet
DC = AC to DC power converter 5V
C = 1000μF capacitor
R = 390 Ohm resistor

More documentation: https://github.com/coreyferguson/workbench/tree/light-dimmer-only/lighting

Any help would be much appreciated!


texts:
I am new to electronics simulation.
I am currently simulating a simple FET where I sweep both the gate and drain voltages.

When I plot the drain currents for low values of the drain voltage I obtain a negative current value.
I am actually not understanding the reason behind this.
I am aware that a small negative current in possible if the voltage between drain and source becomes negative, but here Vds is always >=0.
If you can tell me where´s the mistake, I would really appreciate.
Many thanks


texts: Firmware update using MSPDEBUG goes directly into the debugging console

texts:
I have encountered a strange problem using mspdebug with my MSP430FR5969 launchpad.
I have recently started with msp430 programming. I was interested in running the Curve25519 project on MSP430. I followed there instruction step by step to install gcc-msp430, mspdebug etc with other dependencies. Since I could not find the slac460k.zip file in TI website I downloaded the latest slac460w.zip file.
Now whenever I type

  mspdebug --allow-fw-update tilib

It directly goes inside the mspdebug (screenshots attached).

I think it is supposed to update the firmware with this command.
I can see the red LED glowing after I execute the above command.

Moreover, I can't run any program on the microcontroller. I tried with a small blinkng program from the mspdebug prompt by executing the command

  prog a.out

But I can't see the LED blinking. And the program runs forever.
I will appreciate if you can tell what am I doing wrong here.
I appreciate your help.

Edit :

I used usb connector to connect my device to my laptop.

Edit :
Code for Blinky.

            #include <msp430fr5969.h>

            int main(void) {
              volatile int i,j;

              // stop watchdog timer
              WDTCTL = WDTPW | WDTHOLD;
              // set up bit 0 of P1 as output
              P1DIR = 0x01;
              // intialize bit 0 of P1 to 0
              P1OUT = 0x00;

              P1OUT ^= 0x01;
              // loop forever
              for (j=0;j<=1000;j++) {
                // toggle bit 0 of P1
                P1OUT ^= 0x01;
                // delay for a while
                for (i = 0; i < 0x6000; i++);
              }

            return 0;
            }


texts: What is a common-emitter bjt push-pull output stage?

texts: My professor mentioned it briefly in class, and I've been googling it and all I find is the CC output stage. Can anyone show me a picture of this configuration and maybe describe how it works? Can you provide a source?


texts: How to calculate the maximum current rating of an ammeter manganin shunt?

texts: I want to make a shunt for an ammeter using a manganin wire. I don't know how to chose the wire diameter for the desired current. For example, my shunt will have 0.05 ohms and it must withstand 5A for a continuous usage and 10A for short periods of time. What diameter of wire should I choose ?


texts: how to print a PCB layout for UV etching

texts:
I am new to UV etching. I have a 2 layer PCB layout that I prepared on Eagle Cad. I am confused what layer do I need to mirror?

After printing the layout what side of the paper turns to the UV light and to the board (for both top and bottom layers)?

Edit: I use Jetstar inkjet film (transparent) and I will use ink printer (HP). I will use UV box to transfer the layout onto the PCB.


texts: Why are two transmission used gates to make a D Latch?

texts: In the circuit given below I can't understand what the second transmission gate TG2 is used for. It is connected both to the exit of a Transmission gate and an inverter... so what is the actual input and output of this circuit?


texts: What could be the source of capacitive coupling in these SMPS?

texts:
I have bought two of these cheap laptop power supplies for an audio amplifier I was building.

They work, but with a serious problem: They give mild to strong shocks to anybody touching the ground (or any of the AC mains) and touching the DC output.

I can easily stop that by grounding one of the terminals of the DC output, but they shouldn't need grounding and there isn't even a pin for the ground. There is no conductive path between the primary and secondary windings of the transformer and the capacitive coupling should be minimal.

I tested each power source for conductance between the AC inputs and the DC outputs, and got nothing. Not even in the 10^7 ohm scale.

I also tested applying 80 V DC between the inputs and the outputs to see if any current flowed. Nothing again.

But, when applying 127 V AC (60 Hz), a ~13 mA current flowed between the input and the output of the power source.

Calculating the capacitance, I found that each power source had a ~ 270 nF capacitance between the inputs and the outputs.

This is outrageously high. I measured several transformers I have (LF and HF) and none goes over 1 nF.

What could be the source of all this capacitance?

Thanks!


texts: How can I create a fixed voltage reference output voltage from a varying input voltage?

texts:
Suppose I have the following:

A voltage source that outputs a voltage between 10 and 14 V.

I need to generate a fixed reference voltage independent of the input voltage mentioned above. How can I do this?

Ideally I'd like my reference voltage not to vary more than 25 mV.  So, say for instance, that the reference voltage is 5V then when input voltage is 14 V, the reference voltage must be at most 5.025V and when input voltage is 9 V the reference must be at least 4.975 V.

My first thought is to use a zener diode, maybe 5.6V or 3V. But I don't like this solution as it is a bit power consuming. I don't have any specific maximum value for power consumption, but I'd like it to be as low as possible. Is there any IC that can do this by consuming less than a zener?

I could also use an LM317 but since the voltage reference would feed a few comparators I thought the LM317 might be an overkill.


texts:
So I have this question that I'm struggling to understand and solve, it goes like this:

I want to determine the Thevenin equivalent of my car battery. You measure a voltage of 12.2V across the battery while it supplies a current of 1A. When I turn the headlights on, the load current increases to 8A and the voltage drops to 11.88V. What would be the Thevenin equivalent voltage and resistance?

How would I go about solving this? I struggle to imagine it being a linear circuit.


texts: Input power requirements for "load regulation" tests on DC power supplies

texts:
My question is this:  What is the convention, if any, for specifying a power supply's input voltage value when performing a load regulation test?

Background

A typical specification for DC power supplies is its input voltage range--e.g., \$115\,VAC\,\pm10\,\%\$ for line-powered "AC/DC converter" power supplies,

115 VAC -> [DC POWER SUPPLY] -> Regulated Volts DC Output (CV mode)
115 VAC -> [DC POWER SUPPLY] -> Regulated Amps DC Output (CC mode)

or perhaps for a DC/DC converter power supply the range of unregulated DC input voltages \$V_{in}\$ is specified:

10 VDC <= Vin <= 14 VDC    // nominal is 12 VDC

Vin -> [DC POWER SUPPLY] -> Regulated Volts DC Output (CV mode)
Vin -> [DC POWER SUPPLY] -> Regulated Amps DC Output (CC mode)

Assume I have a DC power supply operating in constant voltage (CV) mode whose output voltage is specified as \$5.0\,VDC\,\pm\,0.1\,VDC\$, i.e.,

4.9 VDC <= Vout <= 5.1 VDC

and whose output power is specified as 10 Watts--i.e., when operating in CV mode the supply's maximum output current is 2 ADC (and its minimum output current is implied as 0 ADC).

Now I want to perform a load regulation test to verify the supply's output voltage remains within its specified voltage window

4.9 VDC <= Vout <= 5.1 VDC

over the supply's full range of output currents--e.g.,

0 Amps <= Iout <= 2 ADC

What is the convention, if any, for specifying the supply's input voltage value when performing a load regulation test?  Does one ordinarily specify/use the nominal input voltage for this test--i.e., 115 VAC or 12 VDC for the examples above--or does one perform the load regulation test twice, once at Vin(min) and once again at Vin(max):

// Load regulation test 1a: Vin = Vin(min)
115-10% VAC -> [DC POWER SUPPLY] -> Regulated Vout @ Imin, Imax
10 VDC -> [DC POWER SUPPLY] -> Regulated Vout @ Imin, Imax

// Load regulation test 1b: Vin = Vin(max)
115+10% VAC -> [DC POWER SUPPLY] -> Regulated Vout @ Imin, Imax
14 VDC -> [DC POWER SUPPLY] -> Regulated Vout @ Imin, Imax

Or perhaps the test is run thrice @ Vin(min), Vin(nominal), Vin(max)?  Or "other"?

(n.b. I understand that a complete answer depends upon "other factors" to include time and cost trade-offs when specifying testing regimes--i.e., what degree of testing is necessary and sufficient for a given product? Nevertheless, I'm interested in hearing some opinions / conventions for selecting the input voltage value when performing a load regulation test.)


texts:
While selecting a diode, I came across these two, which appear to be the same, save the ending part numbers after a "/" (i.e. one is 54, the other 73). I've surmised from JEDEC 609B section 5.3 that the "E3" refers to the leads being pure tin; section 5.1 mentions a "slash-sheet" number, but this refers to PCB base materials, and according to section 7.9, should come before the "E3" designation.
I haven't found an answer in the datasheet. What do the numbers after the slash ("/") mean?