texts: Understanding LED specifications (hobby kit)

texts:
I have an LED that looks like:

It did not come with specs for the LED. In laymens terms, I'm trying to determine the technical term for the following descriptions.

(What is the max amount of current that can flow through this type of LED before it becomes 'unsafe' and blows up) -- What is this term called?

(What is the minimum amount of current needed to flow through in order to emit any sort of light 'minimum light') -- What is this term called?


texts: Changing output voltage of a buck converter by electronically swapping the feedback resistors

texts:
I am going to design a circuit which is going to output some digital signals. The output stage of the circuit will have some level shifters. The level shifters will give flexibility to the user to choose the voltage level (1.8V, 3.3V or 5V) of the output signals. I am planning to place a three-position slide switch on the PCB. According to the position of the switch, one of mosfets will be shorted, and so, corresponding feedback branch will activate and set the output voltage.

Can you please review this idea? I am not sure if the feedback signal will be distorted or not. I think the switching frequency of the buck converter to be around 500kHz. Is this idea feasible? Can you please make some suggestions to improve it, or tell me why it wouldn't work?

EDIT: The switch will be a panel mount one and will stay in a remote location. That is why I am using the mosfets to short the feedback paths.


texts:
While I have successfully cleared all the lcd display with the help of some guys here by a cheat code (because it doesnt really delete the display)for (int i=0; i < 80; i++), Now I needed to delete  single character on my lcd display.

Note:
I am using serial communication with my lcd module. I intensively search the internet but I could not find any solution, Is there anyone who had an Idea to do so?


texts: What does the MCP4725 Power-On-Reset (POR) value indicate?

texts:
I managed to read from an MCP4725 using I2C. In the second byte below, the POR value it gives me is '1' (the whole byte is 11000000)

I know that if RDY/BSY = 1, it means the device is ready to write its EEPROM.
When does POR = 0? What does it mean if POR = 1?
The datasheet gives no information about the value of POR. I think that POR = 1 when the IC's power is >2V and POR = 0 when IC's power is <2V. (But if that is the case, giving me the POR value has no meaning)
EDIT:
Based on the below section of the datasheet, since there is a "after POR" state, I think POR=1 means that the device has "completely woken up from its power-up/reset state and its ready to receive commands".

Since after the reset, the device loads the data from EEPROM to the register (to output its analog value,) this takes some time, and while POR = 0, this event is still taking place.
Am I right?


texts: Electric force at a distant point created by a changing current in a wire

texts:
Regarding the following figure:

A text claims when the current I through the wire |AB| is increased it will set up an electric force f at a point P. And if there will be a wire |A'B'| there will be a current flow across |A'B'| as well. The text claims this is due to the fact that the magnetic field h without changing its direction will be displaced in the radial direction M perpendicular to h.

I couldn't get which law it is talking about in electromagnetic theory. What does the text mean here?


texts: Tracing boolean functions using a TUL PYNQ Z2 board

texts:
I am trying to trace the output of a simple XOR gate using a PYNQ Z2 board. But the documentation and related tutorials are not helping.
My boolean function is as follows: function = ['D2 = D0 ^ D1'].
I am passing it to the boolean generator but how do I check its waveform? I want to send different combinations of D0 and D1 and see D2's waveform for all these combinations, thus verifying the truth table of the gate.
I am a beginner with Xilinx boards, thank you.
My code so far:
function_specs = {'XOR_gate': 'D2 = D0 & D1'}
boolean_generator.setup(function_specs)
boolean_generator.run()

xor_gate = {'signal': [
        ['stimulus',
            {'name': 'A', 'pin': 'D0', 'wave': 'hlhl'},
            {'name': 'B', 'pin': 'D1', 'wave': 'l.h.'}],
        ['analysis',
            {'name': 'Output', 'pin': 'D2'}]],
       'foot': {'tock': 1},
       'head': {'text': 'xor_gate'}}

waveform = Waveform(xor_gate)
waveform.display()

References I have seen so far:

The official PYNQ Documentation (https://pynq.readthedocs.io/en/v2.3/pynq_libraries/logictools.html)
The sample codes present in the board.
https://github.com/Xilinx/PYNQ_Workshop
I even asked a question on the Xilinx forum but to no avail.


texts: Ideas for attaching / connecting / stacking one PCB onto another with no gap

texts:
What methods might be feasible for attaching/stacking one PCB immediately on top of another PCB, with the following conditions:

Zero spacing/gap between the two PCBs
Electrical contacts are needed, not just physical attachment
Assume that the top PCB is about a third the size of the bottom PCB

I'm at the early design stage of a project and am trying to survey the options first, so I'm open to recommendations of standard methods as well as any creative ideas.

Note: I'm already familiar with edge castellations (AKA "half vias"), so other suggestions would be of interest.

For instance, is it possible to design it such that the top PCB has pad-contacts only at the bottom (QFN/QFP style) which are somehow solderable onto pads on the bottom PCB?

EDIT: To answer @Andrew's question:

My purpose of stacking the two boards like this is that the Top PCB will be variable across variants of my device (in fact, variable not only in what the Top PCB contains but also size and number of contacts it has), hence the goal of having one constant Base PCB with pads onto which I can attach a variable Top PCB.


texts: Using diode mode on my multimeter to debug circuits. A good idea?

texts:
I've seen a few YouTube videos where the presenter, who appears to be experienced in board repair of Apple (and presumably other) circuit boards recommends to use your multimeter in "diode mode" to make measurements from a suspected problematic part of a circuit, and compare to a known good board. The boards are not powered during the measurement.

How to Use multimeter DIODE MODE to find ANY motherboard fault - Jessa Jones
Importance of DIODE MODE measurements for troubleshooting - Louis Rossmann

In both cases they recommend putting the red lead to ground and the black lead to the test point (around 6:40 in Jessa's video, and 2:45 in Louis' video).

The advantages are apparently that diode mode measures somewhat faster than simply measuring resistance. In my testing resistance mode took around a second to measure while the multimeter auto-ranges, but diode mode seemed virtually instantaneous.

They both recommend finding a problem connector or IC, and then (with the board unpowered) take a measurement of each pin, and write that down, and then compare to a known good board in the same place. Any readings which are substantially different point to a possible problem.

My questions are:

Why reverse the polarity? You are injecting a negative voltage into parts of the circuit which presumably are designed for positive voltage.
Won't injecting negative voltages damage the underlying circuit? I measured three multimeters I have here in diode mode and found that they used:

7.3V at 1.0 mA
3.3V at 1.4 mA
2.5V at 0.91 mA

I would have thought that injecting -7V into a logic board would cause assorted problems, but both of these presenters are swearing by that technique as a way of quickly debugging. Maybe their meters only inject 3.3V but even so.

From a comment:

  how many volts/mA does the ohm feature use?

Same meters in the same order:

2.77V at 1.0 mA
0.48V at 0.65 mA
0.53V at 0.31 mA

A possible explanation?

Thinking about the questions above, particularly the one about "why use negative voltages?" I have come up with one possible explanation:

If you connect (say) positive 3.3V to a board then parts of it will try to power up. For example, if you connect to Vcc of a chip, the chip will try to power up, or if you connect it to a data line it will parasitically power up.

The resulting readings won't prove a lot. Effectively your multimeter has become a rather under-powered power supply.

However by injecting a negative voltage then the main chips will reject that (through their protection diodes) and thus won't power up. What will be left is the "path to ground" via various resistors and voltage dividers. This would more readily pick up missing or bad resistors, broken traces, bad connections, etc.

Does this sound plausible?


texts: What is the tradeoff between a low and high tolerance in a processor?

texts:
For example, There're 2 processors in which voltages of 1 signals are 1.0 volt. Manufacturer A make it so that 0.95+ to 1.00 volt is also considerd 1, while manufacturer B make the same processor recognize 0.9+ to 1.00 volt as 1. What is the trade off between the two?

Bonus question: Also, are there official names for 1-signal's voltage and 0-signal's voltage?


texts: What kind of capacitor might this be? Value?

texts:
I am trying to duplicate a simple 556 circuit, this capacitor works, but when I try to substitute another cap, it doesn't work.  I need to order a couple dozen of these but want to order the right thing:)  tha cal in question is the flat green one with 103k in the number.
I tried to measure this cap with my vom, and it read .025n.
I dont know , that is accurate, since the .025n stays on my meter display with other components and wont zero out till I change away from capacitance and back again.

Thanks,

Dan


texts:
I have just used an IP in the IP catalog called Multiply accumulate. This IP is supposed to multiply 2 inputs and accumulate the result. I made a control module for it(mac_control) where I instantiate this IP (mac: entity work.MAC port map...) and then I made my test bench. Everything compiled as it should but when I go to the simulation, it doesn't output anything.

I noticed that the port map pins that I set forcefully (for example, ce => '1', rst => '1', etc) were not displayed in the simulation. I don't mean that they they were marked as undefined, I am saying that there was just the black background where the signal should be. So I created internal signals which were initiated with the expected values (signal int_ce : std_logic := '1') and then I linked the signal to the port maps. This made the signals appear on the vivado simulator, but still ... no output.

Maybe I'm missing a library or something. Does anyonw know how to simulate the IP core?

EDIT:
I also tried using the '*' and '+' operators but vivado told me that 0 definitions were found for those operators. I'm almost certain that this means that a library is missing. But I can't same the same for the main problem

EDIT2:
I noticed something else. When I open the sources it lloks something like this:

tb -> multiplier.vhd -> mac.xci -> mac.vhd (this one has a red flag) -> xbip_multaccum_v2_0

I guess there may be something wroong with the mac.vhd. A red flag doesn't strike me as a good thing (it's a little red square at the bottom levt part of the icon in Vivado)

EDIT3:
I'm using Vivado's simulator.


texts: How to control a robot wirelessly using xbee modules?

texts: I want to be able to control my robot wirelessly from my pc via xbee modules. So one xbee should be connected to my computer while the other one will be to the arduino on my robot. I've done a lot of research on xbees but Im still very confused. For example I'd like to control it manually using arrow keys and also be able to control other functions on the robot like headlights etc. But frankly I dont know where to start. Can someone give me a brief introduction to how this can be achieved? Thankyou.


texts: RISC-V Arithmetic Shift vs Operator "<<<"

texts:
I'm new at learning Verilog so some of my practices are based on already existing codes. I was reading the RISC-V implementation of arithmetic shift and didn't quite understand why it's that way when it can be a simple shift operator.

Since I'm a newbie at this topic I want to know if there's any practical difference between both implementations.

RISC-V Implementation snippet:

       //----------------------------------------------
       // Shift Left
       //----------------------------------------------
       `ALU_SHIFTL :
       begin
            if (alu_b_i[0] == 1'b1)
                shift_left_1_r = {alu_a_i[30:0],1'b0};
            else
                shift_left_1_r = alu_a_i;

            if (alu_b_i[1] == 1'b1)
                shift_left_2_r = {shift_left_1_r[29:0],2'b00};
            else
                shift_left_2_r = shift_left_1_r;

            if (alu_b_i[2] == 1'b1)
                shift_left_4_r = {shift_left_2_r[27:0],4'b0000};
            else
                shift_left_4_r = shift_left_2_r;

            if (alu_b_i[3] == 1'b1)
                shift_left_8_r = {shift_left_4_r[23:0],8'b00000000};
            else
                shift_left_8_r = shift_left_4_r;

            if (alu_b_i[4] == 1'b1)
                result_r = {shift_left_8_r[15:0],16'b0000000000000000};
            else
                result_r = shift_left_8_r;
       end

Almost equivalent snippet:

    always @ (posedge clk) begin
        data_out <= data_in <<< shift;
    end


texts: How do I detect the output voltage of the charging controller?

texts:
My project uses Li-ion battery charger LTC4099 (https://www.analog.com/media/en/technical-documentation/data-sheets/4099fd.pdf). And S6E2DH FM4 microcontroller (https://www.cypress.com/file/224786/download). I want to detect the presence of the ouput voltage VOUT of the charging controller (in the attached picture) using the microcontroller. What are some sensible ways to do it? Please let me know. Thanks.
PS: I want to measure using a voltage divider but dont exactly get it because the VOUT of the battery charge controller is varying but not always constant. Isn't it?


texts: Remove 0 Ohm resistor (solder bridge jumper)

texts:
I have an STM Nucleo-64 board that I want to power from my own 3v3 rail. To do so you must remove two solder bridges (SB2 and SB12 in the photos), both made with what appear to be size 805, \$0\Omega\$ resistors that are placed close to other nearby components. Does anyone have a technique for removing these safely?

I considered trying to somehow snip them, but I don't see how to get flush cut snips in there safely. Maybe I could cut perpendicularly through the bridges from above, but even that looks like it would be difficult. I could try to wick them, but it would be a bear.

I think my best idea might be to use a hot air gun and hope the nearby stuff stays in decent shape. Otherwise it might actually be easier to snap the ST-Link from the rest of the board...


texts: DC Motor used in cordless drill - is it polarity-sensitive?

texts: I have an old cordless drill  I've stripped the motor out of. Am I correct in saying all dc motor aren't polarity sensitive? I thought that how you reverse the direction of the motor


texts: Correct MOSFET for logic level switching

texts:
I'm looking to switch a 12 volt 0.5A and 2A load using the raspberry pi's 3.3v GPIO pins.
From what I've read a MOSFET is the best fit for this application but I'd like to avoid wasting energy as heat and having to use a heatsink.
I have some RFP12N10L MOSFET's but I'm struggling to determine if they are right for this application. ThePiHut sell IRLB8721PbF MOSFET's stating they can switch up to 15A without a heatsink so maybe they are a better option?
Thanks!


texts: I am making a 64x32 bit SRAM, I need to use a 6x64 decoder as the Row address decoder. My question, is it possible to design a 6x64 Decoder using  3x8 Decoders?


texts:
Because I live in a bus, I use paid-for hotspots to connect to the internet.
Sometimes I'm quite far from a hotspot, so I was thinking to use a raspberry-pi with both an ethernet connection and a wifi, attached to a long ethernet cable as my router.
Now my questions are about the powersupply and possible interference with the ethernet cable.
So, can I use a Cat5e and use the blue or brown wires to provide power over the same cable ?
(Which I would then have to separate from the rest before they go in the RJ-45 connector, because I don't suppose the raspberry would support PoE)

Or would it better to be using a seperate ethernet cable for the power supply ?

How much Power would I need to provide at the source in order to still have 5 Volts over i.e. a 30 m ethernet cable ?


texts: Why is a switched-capacitor voltage replicator useful?

texts:
The figure below is a switched-capacitor voltage replicator. It is from Reconfigurable Switched-Capacitor Power Converters by Dongsheng Ma and Rajdeep Bondade. You can read it here.

As you can see the output voltage Vout is finally charged to Vin. So why it is useful to use this circuit while it has a voltage gain of unity?
It also doesn't seem to be a voltage buffer either.


texts: How to combine two resistors with a voltage source

texts:
simulate this circuit – Schematic created using CircuitLab

simulate this circuit

Are these two circuits the same? If not, could you please indicate why as well?


texts: Pros and cons of a output discharge of a power distribution switch

texts:
I am looking at a current limited output switch tps2061 and some variation of this part has a output discharge. Based on the datasheet page 16 this discharges the circuit when disabled or in UVLO.

I thought power is usually cut when in those situation? what are the pros and cons of output discharge?


texts:
As a way to improve my meagre FPGA skills, I'm moving some of my retrocomputing projects to purely FPGA implementations in VHDL, where each individual chips have the exact signals interface as they had in the old times. While having a lot of fun, I find that my exotic designs are not exactly what the FPGA manufacturers had in mind when producing chips and toolchains, and I don't get much help from their documentation. I'm intentionally asking a couple of questions together, as I suspect not many people will be interested in distinct detailed answers on the subject.
One of my next designs is a simulated retro DRAM chip (such as the 4164) using some block RAM. How can I duplicate the exact delays for the availability of data after asserting /RAS and /CAS? I found out that the VHDL "after" and "wait" statements are to be used only in test benches, as they are not synthetizable. So what could be the most efficient wait to do that? Should I add an additional high-frequency clock and an internal counter, so as to simulate an asynchronous chip by being internally synchronous? Could I use some kind of delay loop? Something else? As I don't have enough problems yet, I added this additional constraint: I don't want to use any "IP" inside a given simulated chip.
The other side of my quest is about clocks, a subjet I'm not really familiar with. Some of my favourite chips, such as the 68000, perform operations on the falling edge of their clock (e.g. 68000 states S1 and S7). When I learned the basics of FPGA design, I've seen a lot of scary warnings about using both the rising and falling edges in the same design. So how can I simulate such signals? For other chips, such as the 6809, there are sometimes two clocks, one leading the other (Q and E). Is it "safe" to use a PLL and happily drive a single simulated design with two clocks having a slightly distinct phase?
Bonus: I understand that both Vivado and Quartus have the ability to specify timing constraints and perform timing analysis of the designs. I never used them before, as I'm still learning and my main tool is still the waveform viewer. Could those tools be abused so as to assist me when I'm creating original retro-like designs connected to simulated retro components with timing constraints?


texts: Is there anything I should watch out for with cheap "Arduino" copies?

texts:
There's a plethora of cheap Arduino copies on eBay and similar sites, usually originating from the far east, that can be had for a significant chunk less than the official boards, especially if you're buying more than one.

Aside from the moral reasons of supporting the Arduino guys (not that I'm ignoring that, just not considering it for the purposes of this question) is there any technical difference between them, or are they pretty much the same (Arduino are open source hardware after all) will they be, as far as functionally, pretty identical?


texts: A query regarding Thermal Voltage V = KT

texts:
I read thermal voltage = KT ;  K in ev/K and T in Kelvin.

By substituting we get V = 8.620 * 10^(-5) ev/K  *  300K  = 0.0259 ev

But where ever I read, Thermal Voltage is given as 26 mv but It has to be 26 milli electron volts right..??

Can you please clarify on this..??


texts: Minimalistic RTC backup battery charging or a super-capacitor?

texts:
I am trying to provide RTC power backup for a 3.3V system that will be running at the very least 8hrs during the work day. As such I only need up to a month of backup, enough to survive over long weekends and vacation periods just in case the system is powered-down.

Estimated RTC consumption is <3µA.
Minimum RTC voltage 2V.
Charge/discharge duty cycle better than 5:1 (40hrs running over a week).

The main driving design consideration is overall size. So the answers provided to related questions such as this one, or this one, are not satisfactory. I am looking for a minimum-size solution and I would like some input regarding the tradeoffs and filling-in important details.

The first solution that I approached was a super capacitor. I found a 220mF 3.5V supercap that in principle satisfies all of the requirements with only a diode and a resistor to charge it. However the vendor does not specify the self-discharge current, so the duration estimate might be very exaggerated. It clocks in at 11mmx11mmx5mm.

The second solution that I approached is an actual battery. I found this 3V coin cell that has a 1mAh stated capacity, a maximum 5µA discharge current and 30µA maximum charge current. This should last for two weeks. A simple two-resistor and diode charging circuit that accounts for that 30µA maximum current would only provide ~3µA for charging during normal conditions. So I have two choices:

Ignore the maximum charging current and design the resistor divider to provide at least 15µA (to satisfy my charge/discharge duty cycle) during expected normal conditions.
Add a transistor a resistor and a diode to limit the maximum charging current.

As size is the main driver, this solution is very attractive as the coin cell only takes 5mmx5mmx1.5mm. However this size advantage is somewhat offset by the extra transistors and 2 resistors.

simulate this circuit – Schematic created using CircuitLab

Do I have any other alternatives?

Would the super capacitor duration actually satisfy the requirements?

Are there better batteries with a reasonable form factor? (all of the ones I found have very bad mechanical placement for their SMD pads).


texts: What does a bar symbol in parallel with a single inductor indicate?

texts:
Some circuits have parallel bars on their inductor symbols such as:

Does that mean the inductor is wound around a magnetic core instead of air? Is that how a differential choke is represented?


texts: If I want to make an Arduino derivative product based on the Arduino UNO design, and I make no modifications to the firmware loaded on the ATMega8u2 usb chip, do I still have to go off and buy my own VID/PID from USB-IF?


texts: 2.4GHz Bluetooth PCB Trace Antenna Range

texts: I have designed a PCB trace antenna for a BLE module. I used an existing reference design, which is offered to be used in your own design. I am able to connect to the radio, and on a spectrum analyzer the frequency is where it's supposed to be (right in the middle 2.442GHz), but the (effective) range is terrible. With the dev board module I get close to 90 meters without losing the connection but with my board I get about 8-10 meters before it drops the connection. The transmit power seems good but I have a very poor understanding of the amplitude of the frequency. When comparing the dBm of my design and the reference design there is very little difference in the dBm. So, my questions are how can I have the correct frequency but such poor range, what attributes to the range, and what can be done to a PCB trace antenna to increase its range?


texts: Experience with thermal glues/adhesives?

texts:
I'm planning on using a thermal adhesive to bond an LED pcb to an aluminum enclosure.  The enclosure is meant to serve as a heat sink and wick away any heat generated by the LED board.  The aluminum enclosure has a curvature to it, which means that I cannot simply place the PCB flush against its surface.  To that end I'm hoping to use a solution that will fill the gap between the two surfaces (at it's maximum the gap is roughly .063").

In the past I've used thermal pastes to help a heat sink wick away heat from an IC.  I'd be inclined to use thermal paste, but it never quite hardens and I've found often "drips" away over time.  That's generally fine if the chip/board is stationary, but in this case the entire enclosure moves often such that I can already see the thermal paste dripping off the board into some corner of the enclosure.  Not to mention that with a .063" gap I can't imagine traditional thermal paste doing a good job here.

Google provided me with some basic info on thermal epoxies, but I've never used them and am wondering if anyone has experience with them.  If so any advice/commentary?  Are there any solutions that are "resettable" (e.g. can somehow break the bond and redo it)?  Beyond epoxies are there solutions commonly used for this kind of stuff?


texts: Can you provide a short circuit protection circuit to use with a regulator?

texts: I recently shorted my AMS1117 voltage regulator while probing on a DSO. It blew off. I am wondering, is there a short circuit protection circuit which I can use with any configuration voltage regulator.


texts: Understanding certain relationship in Induction heating circuits

texts:
I will try to keep this short as I can and to the point, there is a bit of a back story, so bear with me.

For the last 18 months (on and off as life allows), I have been trying to develop an induction heating assisted machine for 2 reasons.
1 - To learn as much as I can by doing so (I want to actually make the circuits etc myself)
and 2- To actually achieve what I want the machine to do, as I cannot get what I want anywhere else for a decent price and functions the way I want.

I have been researching induction heating circuits for quite a while now. But there is something I cannot work out. And I cannot find any specific info on the internet for exactly what I am asking.

Just a quick review of the machine I need to make:
The machine will be called a Rifle Case Annealing Machine.
It will incorporate an induction circuit to heat rifle case mouths to an annealed state (399C), so that the cases can be reloaded and fired again. This annealing relieves the work stress created by firing the cases.
This is specifically useful for competition shooters, that require all their brass to be of the exact same hardness rifle round, to rifle round, and to get decent life out of the brass, as sometimes, specific calibres can get VERY expensive.

Now, I initially purchased a circuit from ebay - ZVS flyback driver circuit 1000w 12-48v (it came with a copper coil).

I had a play with it and a 36v 13.6a power supply.

Now just using this, I was able to anneal my small rifle (.204 Ruger) rifle cases manually, in about 25 seconds.
This actually cooked the capacitors and blew them up, they got way to hot. Needless to say I learned something LOL.
I then connected water cooling to the coil.
I then replaced with the capacitors with some slightly lower value units, to try to increase the frequency with which the unit operated at. I did some very rough maths, and hypothesised that lower caps, would raise the resonance frequency. Apparently, to heat non-ferrous metals, you need a higher resonance frequency (not sure if this is true). I was hoping to increase the speed that the cases annealed at, as 25 seconds was far to slow.
I did this, with not much noticeable difference, maybe slightly faster.

I then saw that someone gapped a ferrite core, and wrapped the work coil around it a few times.
This made the ferrite core concentrate the switching magnetic field.
https://youtu.be/axM177JrIBo

I tried this and I annealed the 204 brass within seconds!! Success!!
Except incorporating a ferrite core (one I had to gap myself with a dremel and great difficulty) into the machine, and trying to water cool the whole coil was going to prove to be very difficult.
There must be a better way.

Then I came across this video, where someone had actually made a very similar machine to the one I want.

https://youtu.be/EGfGV8xrfak

Now, my question is this:

In that last video, as far as I can tell, the guy that made it, has used water cooling (water bottle in the box), and has obviously used a normal copper coil (not a ferrite core concentrator).

How the hell did he get that brass to heat up so fast!?!?!
Realistically, that is the speed I am after, with that size case.
Smaller cases will anneal faster, which is no problem.

Is he just using more power? maybe 2kw power supply, running at 40 amps?
Obviously he has designed the whole circuit himself, and kudos, as that is an awesome job.
I have actually tried contacting him directly. I got a "read receipt" through the email, and no response :(

Has he used very low capacitors, to get the resonance frequency right for the non-ferros brass to heat fast?
Has he changed the inductors, and some how got the heating speed from that?
I have a feeling he is just using more power?!? I don't know.

I just cannot find any information, on how to speed up the induction heat rate, without putting more power into that system, and having to up the capacity all the components, to handle more power.....

Any ideas electro wizards?


texts: How can I measure ampere flow on the 3phase 3 core (RYB) cables with clamp tester, where I cant separate the phases to measure it.


texts: When issuing GDB `continue` in RAM, can I write to the adresses from which I `continue`d?

texts:
I'm just writing some test programs in order to get to know the STM32F4 (ARM Cortex M4). The development board I'm using has U-Boot preinstalled in flash. When the board is up and running and U-Boot is showing it's command prompt,

I'm connecting with OpenOCD+GDB through JTAG
load my binary image into the RAM (OpenOCD: load_image)
reset the CPU (OpenOCD: reset init)
and set the PC to the location I want to run (GDB: set $pc=0x2000001d)
and run (GDB: continue)

The problem

Most of the times this is working fine.
However, several times I had the problem that when the CPU is in RUNNING state suddenly OpenOCD is displaying this message:

Error: jtag status contains invalid mode value - communication failure
Polling target stm32f4x.cpu failed, GDB will be halted. Polling again in 100ms

If my observation is correct, this only happens when

I'm resetting the development board with the reset button
and typing something into the then-appearing U-Boot prompt.

When instead of U-Boot some other program is present in flash, this problem does not seem to occur.

My assumption

Currently I'm assuming this is caused by U-Boot writing to the RAM location from which issued the continue command. I don't know how continue works exactly, but my theory is that this command affects the debug circuitery in some way and writing to that RAM adress is therefore causing problems.

When my other program is present in flash, everything works fine. Even hitting the reset button works. I think it's because its very small in memory footprint, hence 0x2000001d is unaffected.

My questions

What is continue doing exactly? Does it anything else than just setting the CPU into run mode? Does it affect the breakpoints in some way?
Is my assumption I explained above plausible?


texts: Can a capacitor be used as a dipole antenna?

texts: Can a parallel plate/cylindrical/spherical capacitor be used as a dipole antenna?  Isn't a dipole antenna like a capacitor with a small capacitance?


texts: Voltage waveform at the Emitter of a Buck Converter?

texts:
In one of the questions I am trying to resolve, I am given the Vbe waveform and I am told to draw "waveforms related to Q1". I am guessing that means the emitter voltage waveform - right?

The Vbe waveform:

This is the buck converter circuit:

The Vbe waveform seems very vague to me. I cant understand what that horizontal plateau in the middle of the positive part signifies?

Update:

So since I am asked to draw the waveforms related to Q1, I added teh Collector and Emitter voltages on the same waveform. Am I right?


texts: Best way to send a simple digital signal wirelessly (close-range)?

texts:
I have a small device which powers two vibrating motors. I would like the vibrating motors to be wireless (ie, not actually connected to the device).

Here's some more info:

Here's the vibrating motor: https://www.sparkfun.com/products/8449
I have the motors working in my circuit perfectly, I would just like the signal to be wireless. I'm currently running them off 3.3V I think.

Would something like this work: https://www.sparkfun.com/products/12770?

This is all new to me so I'm unsure how to make it all work. Would it be something like this:

[Device][RFM12BSP] ----- air -----> [RFM12BSP][motor][coin battery]

The issue I have is that I'm not really sending data. I just want to send a simple digital signal (ie, turn motor on, turn motor off).

How would I implement this?


texts: Multiple errors when writing image file with OpenOCD and Stlink v2 to NRF51822

texts:
I want to flash a firmware on my nrf51822 module I was trying an example from Nordic, I concatenated the bin file with the s110 file and it worked fine. Now, when I went ahead to flash the bin file, here's what I got (I followed the wiki http://github.com/RIOT-OS/RIOT/wiki/Board:-yunjia-nrf51822)

> flash probe 0
nRF51822-QFAA(build code: Gx0) 256kB Flash
flash 'nrf51' found at 0x00000000

> flash banks
#0 : nrf51.flash (nrf51) at 0x00000000, size 0x00040000, buswidth 1, chipwidth 1
#1 : nrf51.uicr (nrf51) at 0x10001000, size 0x00000000, buswidth 1, chipwidth 1

for some reason,  I have no idea why size 0x00000000.. any clue?

If I do

> nrf51 mass_erase
> flash banks
#0 : nrf51.flash (nrf51) at 0x00000000, size 0x00040000, buswidth 1, chipwidth 1
#1 : nrf51.uicr (nrf51) at 0x10001000, size 0x00000100, buswidth 1, chipwidth 1

Now when I try to flash the firmware, I get the following:

> flash write_image erase    ~/NRF51822/Board/pca10001/s110/ble_app_proximity/gcc/_build/test.bin 0
auto erase enabled
Padding image section 0 with 12596 bytes
using fast async flash loader. This is currently supported
only with ST-Link and CMSIS-DAP. If you have issues, add
"set WORKAREASIZE 0" before sourcing nrf51.cfg to disable it
jtag status contains invalid mode value - communication failure
error waiting for target flash write algorithm
Failed to enable read-only operation
Failed to write to nrf51 flash
error writing to flash at address 0x00000000 at offset 0x00000000

Previous state query failed, trying to reconnect

It's driving me crazy, I have no clue why that's happening. I couldn't get it to work.

Note: I have an STLink-v2 dongle, no STM32 board involved. I also updated the stlink-v2 firmware using stlink utility.

One last thing, the test.bin file I'm using is basically the output of the following (using S110 v6 and example from sdk v6):
srec_cat ~/Downloads/s110_nrf51822_6.2.1/s110_nrf51822_6.2.1_softdevice.hex  -intel ble_app_proximity_s110_xxaa.hex -intel -o ./test.bin --line-length=44


texts: Converting -3.7V to -32V (both negative), Is it a boost or a buck?

texts:
I need to get create a split supply at +/-32V, but all I have to work with are LiPo batteries. I was thinking something like the block diagram below. The positive part is simple, but the negative part is not so straight-forward.

simulate this circuit – Schematic created using CircuitLab

I tired googling this, but there is not much literature on dc-dc conversion with negative voltage. Main questions I have and need help with are:

When you convert -3.7V to -32V, is that considered a boost or buck? The output voltage is lower, but the absolute value is greater.
Judging by the lack of information, it seems this is not a typical problem, but is it practical?
Can the negative "boost" be done using the same positive boost IC? Ideally, I'd like to use the same chip if possible.
Any recommendation on reading material or schematics? Or any other method of getting +/-32V?


texts:
I live in Melbourne Australia, and I know that if you had two myki's close together they prevent each other from working causing a "multiple cards detected" message to appear. I was wondering if this would work similarly for a debit card, as the bank f'd up and sent me a card with the first and last name mixed up, so I got a replacement with the right name, would the two cards prevent each other from working?

This could be tested with a new card and an expired one as they both still have the technology to communicate, simplified, i'm asking if it works like a simplex radio or a duplex radio (this is an analogy, I dont want to know about radio's right now).

I welcome all input relating to the question at hand and all attempts at making it easier to understand, i am not too good at explaining idea's and wording things on paper/keyboard whilst i have better luck with typing it than writing it

Thanks


texts: Is it possible to create a working JK-flip flop using gate level description in Verilog

texts:
I am attempting to create a working JK flip flop using gate level description in verilog. Although, the design is successfully compiled and simulated, the outputs to the FF are always unknown.

Please note that the design is a modified 'SR-Latch with enable' design (which is known to operate correctly) with the outputs tied to the inputs.

module JK_FlipFlop(input clk, J, K, output Q, Q_not);
    wire    wl0, wl1;

    nand    g0 (wl0, clk, J, Q_not),
            g1 (wl1, clk, K, Q),
            g2 (Q, wl0, Q_not),
            g3 (Q_not, wl1, Q);
endmodule

I have also tried other implementation of the JK Flip-flops using gate level description and the outcome is always the same; with the outputs being unknown.

The test bench used is shown below:

module test_JKFF;
   reg   clk;
   reg   J;
   reg   K;
   wire  Q;
   wire  Q_not;
   // Instantiate the Unit Under Test (UUT)
   initial begin
   // Initialize Inputs
       J = 0;
       K = 0;
       fork
       #5 K = 1;
       #15 J = 1;
       #15 K = 0;
       #25 J = 1;
       #25 K = 1;
       #50 J = 0;
       #50 K = 0;
       #60 K = 1;
       #70 J = 1;
       #70 K = 0;
       #80 K = 1;
       clk = 0;
       join
      // Wait 100 ns for global reset to finish
       #100;
    end

    JK_FlipFlop UUT(clk, J, K, Q, Q_not);

    always #5 clk=!clk;

endmodule

Therefore, any insight that anyone may be able to provide in relation to this question would be very much appreciated.

Thanks


texts: Component identification from vintage tachometer

texts:
For the purpose of understanding how it works, I'm attempting to reverse-engineer the schematic of an analog gauge. For some context, it's an analog tachometer from the 70s, with a scale from 400 to 7000 rpm for a 4 cylinder engine.

I've come across this component on the picture below, with a package and markings I cannot identify. There are two of them on the board (you can see them next to each other), each with 3 terminals. I'm thinking it might be a transistor, but the strange (to me) package confuses me a bit. The markings on the package are:

V15
S10

I'm thinking the circuit might be similar to this one from an earlier ('66) unit, but without the thermistors.

Update: I traced the schematic, and I believe I could identify all parts except for the Zener (the 6.7V measured across it make me think it's a 6V8 one) and obviously the two components from this question (which I now believe to be transistors, though).

I can't make much sense of it yet and I need to double check it, but here it is:

The input signal is from the (mechanical) distributor points of a classic vehicle without electronic ignition. It is a periodic waveform coming from output of the primary side of the ignition coil (low voltage side), and each cycle looks like the blue trace on this image:

The maximum frequency of the signal is 233 Hz (7000 rpm), but in practice it would be less, as the vehicle's ECU would cut off the injection at a max of 5400 rpm (180 Hz).

Essentially, if I understand it correctly, the tachometer circuit should:

attenuate the input waveform to a low voltage signal
convert the signal to a square wave keeping its original frequency
convert the frequency to a voltage/current that is proportional to it
drive the tachometer needle's coil with that current

Would someone have an idea what component it could be? Or perhaps which type of package it is?


texts:
I have the next system, and I want to find the transfer function from d to y.

So I've got the next equations

$$v = Ce = C(r-y)$$
$$e = r - y$$
$$u = d + v$$
$$y = Pu = Pd + PCr - PCy$$

Now I know that:

$$e/r = \frac{1}{1+PC}$$

So eventaully if I am not mistaken I arrive at:

$$y/d = \frac{P}{1+PC}+\frac{PC}{1+PC} \frac{r}{d}$$

How do I eliminate the dependence on \$r/d\$? i.e, I want y/d to be a function of P and C.

Edit: actually, I arrive at:

$$ y = \frac{P}{1+PC} d + \frac{PC}{1+PC} r$$

So the transfer function from d to y should be: \$\dfrac{P}{1+PC}\$, correct?


texts: Stripline (with target impedance) between ground and power planes?

texts:
The common idea for a stripline is that the trace is sandwiched between two ground planes.

My question: is it the same, for the purpose of characteristic impedance, to have a ground plane or a power (VCC) plane?  That is, would the stripline's characteristics be the same if I sandwich the trace between GND/GND, or between GND/VCC, or even VCC1/VCC2?

My instinct is that it should be the same, since for small-signal analysis VCC is the same as GND.  And as I understand it, characteristic impedance aspects go with small-signal analysis. However, I'm not sure that this is the case.  Plus, even if it is the case: are there any requirements on the geometry or decoupling for the power plane(s)?


texts:
I'm working as technician in computer store and I have a lot of scrap transformers . Most of them small and have 6-8 pins  .I wonder, can I use them for my projects ?
If I remember correctly these transformers only work with high frequency and if you feed them low frequency they burn or explode
But I don't know why they heat up without load on secondary coil .
Also I think this the same reason you can't get 5000v with 9V transformer by connect it reverse


texts: Are pins supposed to have the same thickness by some standard?

texts:
I bought a DHT-22 temperature sensor, some other sensors, and some jumper cables. The cable and the pins on other sensors and a Raspberry Pi fitted well, but the pins on DHT-22 seem thinner. The jumper cables cannot stick to the pins, though they still work. I wonder if this is normal or the DHT-22 is a defective one.
That is, are the pin thicknesses supposed to be the same by some kind of standard?


texts: Using a LED as indicator for 9VAC and "borrowing" a 5V-ground does not work. Why?

texts:
The power supply in a Commodore 64 has two voltages: 9VAC and 5VDC. The 9V comes straight from the transformer while the 5V comes from a 7805 and some filtering within the PSU, before outputting on the cable.

Just for the sake of testing, I hooked up a LED and 1k resistor to one of the two 9V-pins, and the other end to the GND-pin (from the 5V-net).

However, that did not work at all. I thought that even if the 9VAC-net does not have a ground, using another ground point in the same supply would work, but obviously it does not.

Question: why doesn't it work?

(What does work is hooking up to the other 9VAC-pin instead of GND, but then the reverse voltage will be too high for the LED [as I recently learned in another thread] so I need another diode in series to protect it, but I'd rather use only a resistor + LED)


texts: Why 2 input bias currents are equal for OpAmp?

texts: In Floyd book it says that 2 input bias currents for 2 inputs ideally equal. I understand if they are equal in a common mode, but how they can be equal in a differential mode if in this case, one input is connected to the ground, or voltages are in opposite phase which at least gives opposite directions of the currents?


texts: High precision frequency to voltage converter

texts:
Lets say I have some 10MHz (+-0.001HZ) precision reference signal that I want to convert to quite a precise 10V Voltage reference. Unfortunately I don't have anything like a josephson junction available (or ten thousands...), and when I spend too much money my wife will kill me.

Looking around for semiconductor voltage references it seems that the highest precision is around 0.01% initial accuracy (the quantum volt doesn't seem to be ready yet), so to be much better than them, I would like to target, say, 0.0001% accuracy.

Looking into existing precision frequency to voltage converters, although having nice linearity components, even if they were sufficient, the devices would still require some reference calibration, which is exactly what I want to avoid.

So is there any technology that fits this gap? That is, intrinsic high precision frequency to voltage conversion without the need for calibration or laboratory grade equipment (and prices)?


texts: How should I set up bypass capacitors for candle flicker LEDs?

texts:
simulate this circuit – Schematic created using CircuitLab
I recently put together a simple project that was three basic LED circuits all in parallel off of a AA battery pack. The interesting twist is that two of the LEDs are of the candle flicker variety and one was a regular white LED. What I noticed was that the white LED also flickers, presumably from noise generated by the flicker LEDs rapidly changing their current draw. In this particular circuit that's an unexpected benefit, but I had thought that the batteries would be able to react to changes in current like this when it's all hooked together with decent gauge wire and no other components. What I have are a few interrelated questions around this:

Is this flicker caused by an inability of the batteries to rapidly react to rapid swings in current on the order of milliamps or by inductance on the wires? (They are some inches long.)
Given that each LED is actually an LED combined with a microcontroller, the technically correct approach would be to drop a 104 capacitor next to each one. But, I sometimes have a bank of these things. Is it possible to (suboptimally, but practically) have them share a smaller number of capacitors and still eliminate enough noise? e.g. I have a bank of ten all in parallel and am pondering adding a capacitor to each end of the bank.
Given that these are usually the load of a circuit and only really interact with the rest of the circuit by being hooked up to ground via a transistor (or mosfet) on the low side and directly to VCC on the high side, how much noise could meaningfully propagate to the rest of the circuit, presuming that the rest is properly designed with bypass capacitors, etc. around relevant parts?

Flicker LED datasheet: https://cdn.evilmadscientist.com/catalog/components/semi/LED/datasheets/BL-L513-B-S3.pdf


texts: Operation details of LUT distributed RAM in FPGA

texts:
I have taken the below image from the source, i have some slight confusion about how read and writes will operate using the 32RAM shown.

Quad port • One port for synchronous writes and asynchronous reads •
Three ports for asynchronous reads

Is ADDRD[4:0] the port responsible for synchronous writes on WA[6:1] and asynchronous reads on the first DPRAM32?
And ADDRC[4:0] - ADDRA[4:0] are the asynchronous reading ports?
Also if a 6input LUT can provide 64memory cells, and DPRAM is 32 memory locations, that means the output must be 2 bits for there to be 32 memory locations. Is this what the DID[0] and DID1 bits are? The 2 bit data bits?
Also, if i write to one DPRAM, does this mean i will write to all DPRAM? Since the Write enable signal WE is connected to all DPRAM32's. How then would someone write a byte of data or 8 bits?
Source:
https://www.xilinx.com/support/documentation/user_guides/ug474_7Series_CLB.pdf


texts: I have this Siemens electrical panel and I am looking for a way to install a lock on the panel door so that it can only be opened with a key. Any suggestions? Are there latches that already have built in locks?


texts: Powering a servo with 9V battery and other questions

texts:
I'm working on a small project. I want to make an internet-connected dog food dispenser to attach to my dog's crate so I can dispatch a network command remotely to dispense it. I have a Raspberry Pi Zero WH with the Pi Cobbler attached to a breadboard and a small servo (Medium Plastic Gear Analog by OSEPP). The idea was to make something like this, where the servo would lift a small cardboard gate inserted into a cardboard tube to let the treats slide down.

I don't have a 4xAA battery holder, but have several 9V batteries and battery clips. I'm a software engineer, not electrical, so I mostly want to confirm a couple of things about the circuit design.

First is that I'm not sure how to calculate how much resistance I would need to use the servo (4.5 - 6V) with a 9V battery, if that's even possible. I know that if you just had a forward voltage drop of 2.4V for example, you would just use 6.6V as your voltage value in Ohm's law and the forward current of the servo as I. But how would I calculate this with a voltage range?

Second is that I'm not sure exactly how to insert the external battery source in the circuit. Do I just insert the positive lead in between the GPIO pin and the servo and the negative lead between the negative side of the servo and the GPIO GND?

Final question is that I just want to know... will the servo continually draw power from the batteries, even when inactive (pin isn't sending a signal to the servo). If so, is there a way I could set up the circuit to prevent this other than just adding a power switch?

I appreciate any help.


texts: how to read current from sense pins of UWS-5/10-Q48 muRata chip with arduino

texts: I have a muRata UWS-5/10-Q48 DC-DC converter chip which has sense pins and I hope to read the current draw of the load which is connected to the arduino and print out the current draw.  I am not sure how to read the current using the sense pins.  Attached is the data sheet: http://www.murata-ps.com/data/power/uws.pdf which refers to remote sensing around page 23.


texts: How does the resistor characteristic work on a MOFSET diagram?

texts:
I'm currently studying n-MOSFETs, and we've just begun the section on using them as inverters. The circuit which we're looking at is:

simulate this circuit – Schematic created using CircuitLab

However, it all seems to depend on this graph, which I'm not sure I understand (in particular, the resistor characteristic line). If there is no voltage difference across the MOFSET, then surely there is also no current—but the resistor characteristic line suggests that 10 mA will flow. Likewise, if the voltage difference across the MOFSET is 10 V, then surely the current would depend on the gate voltage, which is consistent with the curved lines. So why does the resistor characteristic line go to 0 there?


texts: What is "Number of occurrences" in DM16 - Binary data transfer at J1939 CAN-bus protocol

texts:
After I have send a DM14 memory access with the functionality read.

Assume that I'm want to read 646 and 647 address. Then I want to use the lenght = 1, Pointer Type = 1(if I want DM15 message response) or 0(if I don't want DM15 message response), Command = 0 (Write), Pointer (646 or 647 depending on what address I want to read). Pointer extension = 1 (I want to read EEPROM), Key = 0xFFFF(No key) or 0x2505 (I want to write to the address)
I assuming that after I have done a request on the address where I describe how long the values of the address are (in this case 1 byte). Then I expecting a feedback message of both DM15 if I selected Pointer Type = 1, and a message with DM16. Right?
But what does Number of occurrences mean?


texts: Why use a Schottky diode instead of a normal diode on a solar panel?

texts:
I see all forums recommending using a Schottky diode instead of a "normal" 1N4007 diode in parallel with each solar panel cell. Why a Schottky? You don't need speed here - and the voltage drop is about the same (0.7V-1V).)
Schottky forward voltage (drop): PDF1, PDF2, Wikipedia


texts: Analog vs Digital attenuation for an ADC

texts:
I'm designing a digital parametric EQ that will go in front of a high gain guitar amplifier. I want to have the option to boost signals up to 12dB. I plan on implementing this either by attenuating the signal to the ADC by 1/4 (analog), or by knocking off a couple bits either before or after I filter the signal in the discrete domain. I will then amplify the output by 4x via analog means. In terms of SNR and Dynamic Range, which is the better alternative?

The ADC can take the input voltage from a guitar quite easily without clipping. Rather my concern is the clipping of the DAC once I crank up the gain by 12dB.


texts: Connecting a simple device with my secured home wifi

texts:
I am planning on building a simple device, which retrieves information over wifi. The device shall be as cheap and simple as possible, so it won't have a keyboard or a display.

My question is: What possibilities are there to connect said device with my secured home network without having the keyboard/display to chose a the right network or to type in the security credentials?


texts: Which is used in mobile phones? A microprocessor or a microcontroller?

texts: Please help me with this. I'm trying hard to get the specific answer. I want to know a particular answer. What we use in mobile phones? Micro-controller or microprocessor? Or both?


texts: How to power a 6-14v piezo from an Arduino?

texts:
I have a Arduino Nano and I'm trying to run this Piezo Siren off the circuit. The Arduino is currently powered by a USB plug. The siren expects 6-14v and the digital output pins on the nano are giving me about 4.6v. If I run the siren directly from VCC to ground (around 4.70v) then it works, but if I go from a digital output to ground then I get no sound (I do get sound from a smaller speaker on the same pins). If I use the exact same setup with my Arduino Duemilanove then it works as well.

What is the easiest way to get this siren to work based on a trigger from the Arduino? (A bonus would be if I can get the required parts in store from RadioShack so I don't have to wait on shipping anything...)

The Siren:
http://www.radioshack.com/product/index.jsp?productId=2062405


texts: Looking for help improving power control circuit

texts:
I am looking for ideas on improving the circuit below. Any constructive criticism is very much appreciated as well. The following is a long explanation how I arrived at this monstrosity, it can be skipped right away.

The setup:

We have a mixed bunch of 3-rd party and our own devices sharing the same 24V power line. We would like to power them up/down using one more conductor with logic level "enable" signal. The 3-rd party devices are controlled by simple relay + driver (SZNUD3160LT1G) combination.

Our own devices are identical STM32-based boards, one of which is a master controlling that signal, the others are slaves that follow the same power up/down logic.

The requirements:

The logic signal is 3.3V but the inputs should be compatible with 5V as well;
The boards should be able to provide up to 6W power for optional devices connected to them, like sensors, switches, LEDs etc.
The boards should not load control line too much, i.e have high input impedance;
The boards should be hot pluggable, i.e. not interfere with the signal (unless this is master board, of course) and be protected from transients or inductive kick-back from the line.

The schematics at the moment:

To satisfy requirement (2) I've designed somewhat universal footprint on PCB for mounting a variety of POL modules, chosen by specific power needs for each board. Some of them with dedicated EN/!SHDN inputs, like Pololu D24V5F3, the other are simple LDO substitutes, like Murata OKI-78SR. Pretty much anything with TO-220 pinout, including actual LDOs can be used.

Originally I was going to send the signal from MCU straight to EN pin, or maybe use simple buffer. Then I realized that Pololu modules have pull-ups to VIN, that would bleed 24V back to signal line, breaking requirement (4). After considering depletion MOSFETs, analog switches and solid state relays I've decided to use inverting gate driver for this.

What I would like to improve:

Simplify the circuit. Use less and cheaper parts;
Ensure inactive state on power-up. Analog switches and SSRs come in dual packages with NC+NO contacts. This should save PCB space and increase safety. Unfortunately I could not figure out how to use something like DG467 in single supply mode, even though datasheet says it is possible;
Saving one MCU pin would be a bonus. I do have pins available but rather use them for something else. Note, that Sense/Send signal basically depends on device being master or slave and is not changing ever otherwise;
Also R4 looks awfully misplaced to me. It's purpose is to safely send incoming "enable" signal to MCU so that in the absence of "EN" input on installed POL we can still save some power by entering sleep mode. However as it is I think it will simply latch up the outgoing buffer on itself.

Update

Ok, it looks like the original circuit was wrong, so here is updated version. Not only old one had self-latching power output, but it also allowed voltage to be applied to un-powered chips not designed to tolerate it. Hopefully all fixed now. Unfortunately, instead of simplifying this made it more complex.


texts: How to use Slave Select on SPI Transceiver

texts:
I'm an absolute idiot when it comes to wireless technologies, but I'm kinda familiar with protocols over cables. Because of that, I know about the SS on SPI busses and that there is a separate cable for every signle device.
When it comes to Wireless, is there a address inserted at the beginning like in I2C or how is it implemented?

I might be totally asking the wrong question here, but I need a starting point to continue my own research.

Notes:

I'll be using an avr Arduino, so any software implementation to use the SPI interface in a I2C fashion is also suitable.

Also, this is for a project of Home Automation, so there will be many devices, but I will try to keep the communication to a minimum and in bursts.

This is the transceiver I'm looking at right now


texts: Just opened up a defunct Samsung charger... what am I looking at?

texts:
From a preliminary look around the internet, I think there's an axial lead capacitor, a couple of ceramic capacitors, and a couple of electrolytic capacitors.

I'm also thinking that that's a resistor down the bottom there.

In this second one, I recon I'm looking at a bunch of IC's and transistors, but, beyond knowing the two basic transistor types (PNP and NPN), I don't really know how further to identify them.

Any confirmation or correction on anyone's part would be great!


texts: How to choose the impedance of a BNC adapter?

texts:
I am trying to set up lab equipment to measure my soon-to-come sample, but I couldn't get my mind around one thing, impedance termination. I will tell you what I have, what I want to get, and my concerns. My probes are already connected to coaxial wires that are  terminated by trixial connectors. However, my oscilloscope/function generator/etc all have BNC connectors. So i need to get a triaxial to BNC adapter. my concern is, do I get a 50 ohm or 75 ohm adapter. What is it based on? The function generator? The coaxial wires I already have? how do I know if it is terminated by a 50 ohm or 75 ohm? (I cannot get in contact with the person who ordered them, nor i have their datasheets, they are just there and I have to figure it out with what I have).

I understand that they nature of my measurements are also important. But I am not asking if I have to change the wires I already have, I want to work with them, and then maybe change them latter to what better fits my measurements. Most of my measurements are DC. so does it matter at this point? I do measure a square wave of about 300 MHz, is this considered high frequency?


texts:
I was studying the Noninverting and the inverting Comparator with Hysteresis from the book "Practical electronics for inventors".

NonInverting

Inverting

I understand that when the comparator has an open collector then V_{out} is low (V_{out} = GND) and I agree with the relative schematic provided by the book.

The problem is related to the case when V_{out} is high. I think that the correct circuit are the following, not the one in the book. Am I wrong?

Thank you!

simulate this circuit – Schematic created using CircuitLab

I've corrected the two mistake suggested by @Cristobol Polychronopolis


texts: Measuring voltage drop across 10 ohm, 100 ohm and 10 kilohm resistors (one at a time) - very simple circuit

texts:
Below is a picture of my very simple circuit.

There are three resistors 10 ohm, 100 ohm, and 10 kilohm. I connect them one at a time in serial fashion and measure voltage drop across them. When I measure battery voltage I get 6.5 Volt and this is what I expect  as voltage drop on all of my measurements, but here is what I get:

When I measure voltage drop across 10 ohm resistor I get 0.2 volt.
When I measure voltage drop across 100 ohm resistor I get 1.0 volt.
When I measure voltage drop across 10 kilohm resistor I get 5.8 volt.

Why do I get all these different readings and not something around 6.5 Volt?
P.S. On the image the circuit is not closed, but this is how I took picture, circuit is closed on all measurements.


texts: is there any different characteristic between these two crystal?

texts:
I have two 12MHz crystal with through-hole package. It is intended to use for MCU crystal.

On top of the crystal, one is written "12.000" and the other is written "E12.000AKDI".

Anybody know what is the different between them???

Sorry if its sound like a very basic question...


texts: No deflection in voltage regulator but the circuit works fine

texts:
I have connected a voltage regulator (range 0- 300V) to my Air conditioner. The Air conditioner has three wires neutral,live and Earth. (I doubt if the connection is right). The Air conditioner turns on successfully after connecting to the regulator but the there is no deflection in the voltage regulator. (the needle always stays at 0V). Also the outside AC condenser doesn't start probably doesn't start cooling because of this.
I wanted to know if this could be due to a wrong wire connection between AC and the voltage regulator and what if the connection is right and i connect the wrong wires the regulator can it also affect the appliance?
And what could be the possible reasons for the voltage regulator showing no deflection and staying at 0V.
P.S - the voltage regulator and Air conditioner turn on fine and show a green light.
Image of the voltage regulator-


texts: PMR446 interferes with small electronics?

texts:
Some small electronic devices react to PMR446 adversely temporarily, when exposed to a PMR446 transmitter, during the transmission.

Portable DVD player: Green horizontal stripes on screen. Increasing if I hold the PMR446 transmitter near.
Portable CD player (discman): Laser lens loses track, CD spins up very fast; also indicating low battery.
Boombox CD player: Skips and noise hearable if too near to laser lens + fart sound at speakers.
Standalone DVD recorder: Nothing, surprisingly.
DECT unit: Display brightness decreases temporarily.
USB Multimeter: Display lower current than actually flowing (e.g. 1.2A instead of 1.6a). Sometimes, voltage jumps up to 9.99V (highest displayable amount).
CD boombox: Fart sound from speaker.
Toy robot: Do random moves.
Toy phone benign girl: Decreased speaker volume; ability to be enabled by the PMR446 signal.
Portable standalone LED torch gets dimmed.

How can these interferences be explained technically?


texts: Passive POE: Need 5V @ 2A at the destination

texts:
Having a bit of trouble finding the right information on google, and I'm worried I might fry some cables so I thought it best to ask some far more knowledgable than myself.

I want to connect 2 or more devices, giving them 5V/2A plus networking between them.

I figured to do so with the least amount of cables, Passive POE would be a good choice. The distance isn't far, probably maximum 20ft, as each device will be somewhere in a car, connected in to the boot/trunk area.

I'm looking at splitters and injectors, from what I've read its not as simple as just injecting 5v and it'll work? I have to worry about loss and also heat.

So my questions are, what is the best way to get 5V with max 2A current to the destinations? Do I need to send higher voltage to ensure it doesn't drop below 5, then use a regulator to ensure 5V? If I do that, the power will also be higher therefore more heat, is that ok?

Studying Wikipedia page I've read "Category 5 cable uses 24 AWG conductors, which can safely carry 360 mA at 50 V according to the latest TIA ruling"

50v * 0.36a = 18W, so if I were to send 9v * 2a = 18W. Then I could use a regulator to drop the ~9V(allowing for loss) down to 5V. Does that sound reasonable?

Many thanks


texts: how to show a bunch of numbers one by one on a seven segment display

texts: The question is on the title. I just need a starting point like should I draw first the state diagram? I need to show the 150707926 on one seven segment display one by one by using logic gates. Thanks a lot.


texts: 2 LEDs in series with resistor at 3.3V won't light up, one LED works

texts:
I am making a simple circuit with 2 LEDs but it doesn't work - the LEDs do not turn on when I supply 3.3V power to the circuit. (I've tried connecting one LED and it worked.) The resistor is 330 Ohm.

Any thoughts or ideas, please?


texts: Passive components swapping and replacement

texts:
I am trying to writte a small note for our staff when they purchase components. Quite often some resistors, capacitor, inductor, diode and transistor (NPN and MOSFTET) may not be availble on the market.

For this reason swapping or replacing some components might make sense after the engineering to review those swap proposal. I have already roughly established how to replace or swap capacitor based on several criterias like this:

CAPACITOR (C)
Brand: swapable
Value (F): should be the same
Rating (V): take the same or you can take higher value
Tolerance (%): take the same or lower %
Temperature range : same or bigger range including the current range
Footprint: as to be the same otherwise can not solder on pcb
ESR: ??? (I didn't find out this)

RESISTOR (R)
Brand: Swapable
Value (Ohm): should be the same
Rating (W): take the same or you can take higher value
etc..

I am trying to establish the same format for D, L, Q, S, J

What parameters seems the more obvious for you for those 5 other components mentionned above ?

Thank you very much for your help


texts: What is the simplest way to turn on the ESC with PWM input?

texts:
I have an ESC like in the picture and I want to test a motor with it. I don't have any PWM source. Can I connect something simpler (like a DC source) to it to make the motor rotate?
(Red arrow points input of interest but it's not obligatory)


texts: I bought two CC41-A BT modules. First I want to buy HM10 modules. I wonder if I can connect this two CC41-A to send and read data wirelessly. I look in datasheet but I cant find suitable AT command (I think I need some like AT+CONN). Is it possible to connect this two modules or I must buy orginal HM10?


texts: When to use kernelspace and when to use userspace?

texts:
Suppose I have an embedded device like a rapsberry pi and would need to communicate with a module over e.g. i2c. When would it be a good choice to try to communicate with the module by writing kernelspace code?
I know that there are libraries available that allow you to communicate with the module via i2c by writing userspace code. When would you rather go for the latter solution?


texts: Why does the output voltage from 180W ATX PSU on +12V rail deliver only +9.6V to +9.7V?

texts:
I recently got three ATX PSUs which I plan to use as bench supplies. I've successfully managed to get one of them (250W) converted and running as bench supply. But the other two a 150W and 180W. The former only has a click when I power it up and has no output voltage nor does the fan spin.

Now the third 180W PSU is the one my question is related to. I shorted the GREEN and BLACK wires and the PSU fan is spinning and the out put on +5V and 3.3V rails are 4.9V and 3.4V respectively. But on the +12V rail the output is only 9.7V and when I connect a load (CPU fan) on the +12V rail it did not run and the PSU shut after like 10 sec.

I even tried connecting it to my UPS and it is when I noticed that the "SITE FAULT WIRING" LED came ON. Anyone has any idea what could be the possible issue here.I know there is high voltage and precaution needs to be taken so if its a small issue that I can rectify I'm planning to rectify it by myself.

Thanks in advance guys.


texts:
I use stm32f030 and I use st eeprom emulation library. I want to know how many variables I can save in eeprom? I have 48 variables and in this case, I have to create 48 pages? Is it possible to save more than one variable in one page? Or I have to save each variable in one page?
After writing and reading for several times, sometimes the memory loss the defined variables. This is the code that I use for saving my variables.
FLASH_Unlock();

EE_Init();

for(k=0;k<=3;k++){ data = pass_2[k]; EE_WriteVariable( ++i , data ); }

for(k=0;k<=3;k++){ data = pass_3[k]; EE_WriteVariable( ++i , data ); }

for(k=0;k<=3;k++){ data = pass_4[k]; EE_WriteVariable( ++i , data ); }

for(k=0;k<=24;k++){ data = z1[k]; EE_WriteVariable( ++i , data ); }

for(k=0;k<=2;k++){ data = z2[k]; EE_WriteVariable( ++i , data ); }

for(k=1;k<=2;k++){ data = z3[k] ; EE_WriteVariable( ++i , data ); }

for(k=0;k<=10;k++){ data = phone_number[k] ; EE_WriteVariable( ++i , data ); }

for(k=0;k<=24;k++){ data = z4[k] ; EE_WriteVariable( ++i , data ); }

for(k=0;k<=24;k++){ data = z5[k] ; EE_WriteVariable( ++i , data ); }

EE_WriteVariable( ++i , relay );

EE_WriteVariable( ++i , counter );

EE_WriteVariable( ++i , zs);

EE_WriteVariable( ++i , check);

if(lcd_HD_786543 == 22){ flash_ch = 457;    }

EE_WriteVariable( ++i , flash_ch );

FLASH_Lock();


texts: Direct Phone Charge from Solar Cells via USB

texts:
I have a 19V 0.7A series of solar cells I'd like to connect to a standard 5V USB breakout PCB for phone charging. Do I need to worry about causing damage to the phone or battery without a regulator?

In other words, is the charging regulator in a typical phone capable of regulating 19V 0.7A?


texts: What is affected by switching noise - do I need to care about it?

texts:
EDIT:
Load side is build up like this :
ESP > Shift Register/Expander > NMOS > SSR DC >
3 x Pumps
(uses V_in or external power supply via SSR AC)
ESP > Shift Register/Expander > NMOS > SSR DC >
Heating Elements ( external power supply)
ESP > Shift Register/Expander > NMOS >
~8 Valves (500mA - 12V trying to get the Datasheet for them)
I can't choose between Shift Register (TPL9201 - higher mA for NMOS switching) or I2C Expander (MCP23008 - simple to use and cheap but low mA)
Everything that needs to use 5V (currently switched by a RPM5.0-2.0):
ESP32, LAN8720(+ RJ45 Module - Needs 3V3 but I get that from the ESP so I count it in here), maybe the MCP23008 +
bunch of waterflowsensors YF-S201 and digital thermometer DS18B20

All my post kinda are about the same project so who remembers my name maybe knows why I am asking this.
For the project I have to have a 12/24Vdc Input Voltage depending on the user and regulate it down to 12V and 5V.
I learned here and somewhere else that simply the best method to do that is to use a Buck-Boost Converter from 12/24V -> 12VDC and a Buck from 12Vdc -> 5VDc. I use switching because I the load uses a min of 2A and max of 8A which just cost to much place for linear regulator cooling.
As I tried to simulate this a bit in SPICE and TI Webbench i stumpled over switching noise. My supervisor stated that he wants a stable voltage but doesnt specifiy if it has to be low noise aswell.
On the load side I have the following :
~8 electrical valves, ~3 pumps, a bunch of SSR(DC and AC), an ESP32 who sends and recieves the signals(Ethernet added) some Shift Register / Expander for a bunch of NMOS who switch the valves and SSR.
I tried to read a bit abouse voltage/ switching noise and it only seems to affect ADC or audio signals. But in my layout I don't use this so would I need to care ?
Also what about PCB desing, do I need to watch for extra short routes on the noise affected lines like I need to watch the Ethernet 50Mhz osz?
Thanks for any help!


texts:
I have followed this tutorial on building a basic Li-Ion charger for a single cell.
I have the output from the LM338 set to 4.2 volts as described in the tutorial but dont seem to be able to get the led to light with the battery not connected or with the battery connected and full.
The opamp output voltage never seems to change from low to high.
I have removed the 3V3 zenner diode from my circuit as I was advised to do this.
The only other difference between my circuit and  the one in the tutorial link is I'm using a LM358 opamp as opposed to the 714 opamp.
Would using the LM358 make that much difference or is the circuit design unfeasible anyway?

simulate this circuit – Schematic created using CircuitLab


texts: Designing a LiIon battery pack & charger for a Roomba 400.

texts:
I have a device with a 14.4V battery  (a Roomba) and I wish to design a LiIon battery + charging system to replace the existing arrangement.
I would like to charge it with the standard charger that comes with the Roomba. The current battery box will take 8 - 18650 size cells.

My question is will a 4 cell, 14.4 V 4S Li-ion Lithium Battery 18650 Charger Protection Board 15A work to protect the batteries so I can use the standard charger that will provide 20 V to the charger protection board?

I was looking at using this:
http://www.ebay.com/itm/321820489871?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Any ideas?  Thanks!


texts: Calculating output voltage and current of photodiode for input towards ADC

texts:
I need to make something that reads brightness value of an LED from voltage output of photodiode.
I will be using the following parts:

OSRAM OSTAR LE UW E3B datasheet
Summary:

Forward voltage Vf (typ.): 20.8 V at forward current If = 700 mA
light emitting surface: 2.1 mm x 3.2 mm
Luminance: 22 x 10^6 cd/m^2
optical efficiency: 65 lm/W at 350 mA

Hamamatsu Si-PIN diode S6036 datasheet
Summary:

Reverse voltage Vr: 12 V
lens: phi 7 mm
sensitivity: 0.56 A/W
short circuit current: 30 uA
dark current: 0.1 nA

I will see the voltage output as drawn in this figure

And voltage input range of my ADC equipment is within 2 volts peak to peak and +/- 3 volts.

I need to know which resistor I need to use, or whether I need put amplifier or attenuator,
in order to adjust output voltage level from photodiode towards ADC input.

To figure out it, here's my calculation:

sensing area of photodiode: 3.14 * (0.007 / 2) ^2 = 3.848451e-5 m^2 # 0.007: lens phi
candela value into sensing area: 22e6 * area = 846.65922 cd
candela-Watt conversion: 1 cd = 18.3988 mW over a complete sphere
watt value: 15.57751 W
current output from photodiode: watt * sensitivity = 8.7234 A
assume that + 2 volts is the maximum acceptable, 2 V = 8.7234 A * R
thus, I should use resistor with R = 0.2292684 ohm

But, I think 0.23 ohm is absurdly small.

Since I'm not familiar with electrical engineering, circuitry and optical,
I have totally no idea whether my calculation is correct or not,
and whether I use the terms in the equations with right interpretation.

Another problem is, I think current output from photodiode towards ADC does matter.
If it is too high or low, ADC will be fried or breakdown due to too much current drain.
I'm not sure that it is correct or not. If it is wrong, please fix the statement.
Back to the question, anyway, is it correct that the current matters for ADC?

FYI, ADC that I will use is on LFRX daughterboard (schematics) for USRP.


texts:
In the following paper on applications of Game Theory to power control in communications,

http://mackenab.ece.vt.edu/wp-content/uploads/2011/06/mackenzie2001b.pdf

Why is the Signal to Interference and Noise Ratio (SINR) inversely proportional to the transmission rate R?

The expression for the SINR can be found in section III of the paper.

Thanks


texts: Replace 12V 2A centrifugal pump with 12V 1.4A peristaltic pump

texts:
I bought a liquid filling machine -http://a.co/d/8FMFWIU. There is a centrifugal pump model Dp 521 2Amps 12Volt.  I want to replace this pump with a peristaltic pump. The pump is controller by a micro controller.

The pumps that i find are rated as 12volt / 1.4Amps.

Will the difference in amps cause an issue? I am guessing the system will run slower and the new pump should only draw the current(max 1.4a) that it needs and i shouldnt run into an overheating issue. am i correct?


texts: What is the difference between many core and multi core?

texts: These terms seem to be same but in a guest lecture i found that they are not but i have not been able to find the difference even after googling around for a while .


texts: MOSFET power supply ON with no MCU input

texts:
I have a MOSFET circuit that a microcontroller manipulates (using its GPIOs) to control power to other devices.  I noticed yesterday when I detached the microcontroller from the circuit the LED on the board was still lit up.  So this means that 5V on the MOSFET's supply was making it to the drain and hence the R_load.  Below is the schematic for the circuit.  Is this failure by design or some other failure going on?
When should I expect 5V supplied to the R_load (GPIO: 3.3V, GND, open circuit)?


texts:
I find this circuit in an old book.

Regardless what is the task of this circuit, i wonder why the op amp symbol is unusual(curved)?

This is the datasheet of LM301A: http://www.utm.edu/staff/leeb/LM301.pdf

But the other circuit in the same book using the traditional symbol for the op amp


texts: Problems with Arduino PID tuning on DC motor

texts:
I'm using a shaft encoder attached to a DC motor to measure RPM, a L293D IC to drive the motor and a Arduino board. My objective is to control the DC motor speed to roughly 200 RPM, and I'm trying to use the PID library of the arduino to achieve this. My problem, right now, is with the tuning. The system oscillates a lot, and I've tried several methods, but nothing seems to work. I've tried setting Kd and Ki to zero and adjusting Kp until I get a steady oscillation, without success. Also, adjusting Kd isn't doing damping. I've tried using a simple Python program to plot the RPM in function of time and this is what I'm getting:

Below is the Arduino code I'm using:

#include <PID_v1.h>

#define SpeedSetPoint 200

double Input, Output, Setpoint; //PID Variables

int potKp = 2;
int potKd = 3;
int potKi = 4;
float Kp = 0, Kd = 0, Ki =0;

PID myPid(&Input, &Output, &Setpoint, 0, 0, 0, DIRECT);

//RPM Counter
unsigned long start;
const byte encoderPinA = 2;//A pin -> interrupt pin 0
const byte encoderPinB = 4;//B pin -> digital pin 4
volatile long pulse;
volatile bool pinB, pinA, dir;
const byte ppr = 25, upDatesPerSec = 2;
const int fin = 1000 / upDatesPerSec;
const float konstant = 60.0 * upDatesPerSec / (ppr * 2);
int rpm=0;

int outputValue=0;

//DC Motor Pins
int pwm = 5;
int motorA1 = 10;
int motorA2 = 9;

void setup(){
  Serial.begin(19200);
  Input = 25;
  Setpoint = SpeedSetPoint;
  myPid.SetMode(AUTOMATIC);

  attachInterrupt(0, readEncoder, CHANGE);
  pinMode(encoderPinA,INPUT_PULLUP);
  pinMode(encoderPinB,INPUT_PULLUP);

  pinMode(pwm, OUTPUT);
  pinMode(motorA1, OUTPUT);
  pinMode(motorA2, OUTPUT);

  //Start DC Motor
  digitalWrite(pwm, HIGH);
  digitalWrite(motorA1, HIGH);
  digitalWrite(motorA2, LOW);
}

void loop() {

  Kp = analogRead(potKp)/100.0;
  Ki = analogRead(potKi)/1000.0;
  Kd = analogRead(potKd)/1000.0;

  myPid.SetTunings(Kp, Ki, Kd);

  if(millis() - start > fin)
  {
    start = millis();
    rpm = pulse * konstant;
    rpm = abs(rpm);
    Serial.println(rpm);
    pulse = 0;
  }//End RPM reading

  Input = rpm;
  myPid.Compute();
  outputValue = Output;
  //outputValue = map(outputValue, 0, 400, 180, 255);
  analogWrite(pwm, outputValue);

  Serial.print("RPM = ");
  Serial.print(rpm);
  Serial.print("\t");
  Serial.print("Kp = ");
  Serial.print(Kp);
  Serial.print("\t");
  Serial.print("Ki = ");
  Serial.print(Ki);
  Serial.print("\t");
  Serial.print("Kd = ");
  Serial.println(Kd);
}

void readEncoder()
{
  pinA = bitRead(PIND,encoderPinA);
  pinB = bitRead(PIND,encoderPinB);
  dir = pinA ^ pinB;          // if pinA & pinB are the same
  dir ? --pulse : ++pulse;    // dir is CW, else CCW
}

Any tips?


texts:
Hi just having some issues understanding what's happening with my opamp circuit.

Vin is a Sine wave at 1kHz and VG is 4.5V.

From what I understand this circuit should boost the signal I provide it with my guitar. Simulated the circuit on LTSpice which provided the expected output at Out. But when I built the circuit, and supplied it with an input signal from my guitar and output into a guitar amp, it was significantly more quiet than what the guitar would sound going straight into the amp. What would be the reason for the signal being so quiet and what would I further need to read up on to understand what is going on with the opamp circuit.

EDIT: For the built circuit I used an NJM4560D opamp.


texts:
Find the the length x of the transmission line of \$100 \Omega\$ characteristic impedance where the load \$Z_L\$=\$100 + j 100 \Omega\$ becomes purely resistive. Also find \$R_x\$. Assume \$VSWR = 2.6 \$.

This problem I am trying to solve without using a smith's chart i.e. algebraically. A help with the formulae or the steps would be really kind.


texts: Beginner PLC: Configure Ethernet/IP Connection

texts:
I am really new to PLCs programming, connecting, etc. I received a 1756-L72 with Logix5572 Processor and an EthernetIP card. My goal here is to connect it to my laptop along with another device (a Bar Code Reader). Both devices are connected to an unmanaged ethernet switch and one of the port to my laptop.

Now the problem is that all my Rockwell Softwares are on a VM. Therefore, I need to connect all those devices to the VM on my laptop and it does not seem to work.
My ethernet IP on the VM is 192.168.198.128 while my PLC is 192.168.0.205. I know i have to get the 3 first equal but I don't know how to change my PLC IP address. I tried following this website steps but it did not work.

I know it might not be clear, so I'm available to answer any questions you guys have.

Thanks,
luisarcher


texts:
I have been working on a PIC24FJ128GA310 development board for for some time now and recently got a PCB made. If I try to move my code into the new board all timing related math and functions are failing on HS oscillator even the UART lines wont work at the desired baud rate. The device does not run when I put it to XT oscillator.

After some debugging, I found out that the PLL module wasn't getting locked. I have a 8 MHz oscillator with PRIPLL config bit on. So, instead of having FCY of ((8*4)/2) I have (8/2). The case is true if I have POSCMD as HS. But if I put POSCMD as XT, the controller just wont work at all. I am unable to debug the code with POSCMD as XT, IDE says device is not ready for debugging as some config bit is incorrect or the emulator is not wired properly. I know for sure the pickit3 connections are fine because when I change the POSCMD to HS or put the device to work on internal oscillator I am able to get into debug mode.

I tried doing a while(OSCCONbits.LOCK == 0); at the starting to check if the PLL module start-up timer is satisfied. But it never out of that loop. I also tried to start up with internal oscillator and then switch to external oscillator and PLL without much luck.

After some research online I got to this thread,  which says the capacitor on Vcore pin should be causing the problem. I changed that capacitor to a through hole 10uF tantalum. But still the issue remains unresolved.

Here is the schematic and layout of relevant sections.

Oscillator Circuit

Vcore pin

Layout of both. Bottom Layer

I have run out of options and need some help. Please suggest any other course of action. Thanks for any help.


texts: Struggling to understand series connections based on experiment

texts:
I'm having some issues understanding how series connections work based on an experiment I did at school.

I took two lamps, and then connected them in series so the power initially goes to the first then the second. My book tells me that in series connection, the current stays constant throughout the system, which is also what I measured (1,86A), and the voltage potential should split between the two lamps, which I could also see (6,55V + 5,16V almost equals the total potential of the system at 11,86).

This I could also see, as one of the lamps (the one closest to + on my power supply) were shining much brighter than the other one. What I don't understand is, given how the resistance of the lamps are the same, how does this make sense?

According to Ohm's Law, U=I*R, this doesn't make sense. Given both a constant I and the same R across each lamp, U should really stay the same too?


texts:
I was using my 12 V Power Supply, and suddenly a spark occured near the AC input terminals. The power supply stopped functioning. I opened up the casing and found some blackish colour near the 250V 3A fuse as shown:

I have never worked with these fuses. I wanna know if these fuses can make a big spark (as happened in my case), if overloaded. Simply put, could that spark be potentially caused by this fuse?


texts: Can someone provide me the function table for \$ 74xx184 \$?

texts:
In Practical Electronics for Inventors, Paul mentions of these as BCD-to-binary encoders and shows a method to cascade them, but gives no function table to see why it works.

On the net, I’ve able to find only one datasheet for it, which also is not clear as to what it means by Binary Words column in its function table.


texts: How can I resolve the error "Net wire X has multiple names"?

texts:
The message "Nets Wire AHS2 has multiple names" is shown as a warning in Altium.

How can I solve this please? I spent more than two hours and I couldn't locate the problem.

PS: I know it is a warning but I want to make it disappear.


texts: Find the phase angle between two functions

texts:
Apologies if this is better suited for a mathematics forum, it's from my circuits textbook so I've decided to post here. Below is a practice problem from the textbook, with the provided solution.

If I try to convert i1 to a positive cosine function, I get 4cos(377t+140) by shifting -90 (converting to cos) and then shifting +180 (negating the amplitude). So I am then comparing i1=4cos(377t+140) and i2=5cos(377t-65), so a 205 degree phase angle between the functions, where 210 is the stated answer. Is this a mistake in the textbook? I spend hundreds for textbooks and I've spent more time verifying errors than reading... :( oh well
Additionally, it seems to me which function leads which is rather relative as I can shift any function 360 deg, any easy reconciliation?


texts: How to simulate a composite video input signal in ltspice

texts:
I want to simulate this video driver circuit (i think it's called that) in ltspice

I found this design from this very nice video: https://www.youtube.com/watch?v=lqSiMKwfZsY by the videolabguy.
To simulate the same circuit in ltSpice,  I'll need to have a sample analog video input file. I cannot find this anywhere. Earlier, I had simulated an audio amplifier in ltspice - for that, I provided the input as a .wav file (which is accepted by ltspice). I'm not sure how to do this for analog video input.
I have found a way to convert the usual video format to NTSC standard, which i believe is the standard for the analog video input used in this project. But how to add this video input in ltspice is beyond me. Is there any way to do that in ltspice, or is there any other simulation software I have to use to simulate video input?


texts: Generating a (relatively) large current from a small battery at 2 Hz?

texts:
So, I'm running into a few roadblocks and am seeking advice.

I'm trying to use a very small 6V battery to provide 1.5 mA at 2 Hz to a ~100k load.

I intend to use a small microprocessor and a BJT/MOSFET to regulate the frequency and application of current. However, what I'm struggling with is how to achieve this kind of current from such a small battery. I don't have much practical experience with electronics. Would it be feasible to use a capacitor to charge up while waiting for the "on" cycle? How can I regulate the current when the capacitor discharges?

Any advice to get me started a bit would be greatly appreciated. I've been researching a bit on constant current sources and I'm mostly struggling at the power supply aspect. I'm restricted to a very small battery for input.


texts: Simulink - STM32 - PIL test communication error

texts:
I have a Simulink model that contain an algorithm block. I built the generated c code succesfully to STM32F4-discovery board. (I read that from diagnostic viewer.) I used SIL/PIL Manager App to make PIL test. I selected serial communication at configuration panel. When I run the PIL simulation I get this error:
The timeout of 10 seconds for receiving data from the rtiostream interface has been exceeded. There might be multiple reasons for this communications failure. You should:
(a) Check that the target hardware configuration is correct, for example, check that the byte ordering is correct.
(b) Confirm that the target application is running on the target hardware.
(c) Consider the possibility of application run-time failures (e.g. divide by zero exceptions, incorrect custom code integration, etc.).
Note (c): To identify possible reasons for the run-time failure, consider using SIL, which supports signal handlers and debugging. If you cannot find a solution, consider using the method setTimeoutRecvSecs of rtw.connectivity.RtIOStreamHostCommunicator to increase the timeout value.
This is my example model:
This is the diagnostic viewer outputs:
.### Connectivity configuration for "C:\Users\atakan\Desktop\milpilsil\mult_ert_rtw": STM32F4-Discovery (Serial) ### .### Preparing to start PIL block simulation: denemepil/mult ... .### Using toolchain: GNU Tools for ARM Embedded Processors .### 'C:\Users\atakan\Desktop\milpilsil\mult_ert_rtw\pil\mult.mk' is up to date .### Building 'mult': "D:\MATLAB\bin\win64\gmake" -f mult.mk all MW_GNU_ARM_TOOLS_PATH = C:/PROGRA~3/MATLAB/SUPPOR~1/R2020b/3P778C~1.INS/GNUARM~1.INS/win/bin C:\Users\atakan\Desktop\milpilsil\mult_ert_rtw\pil>cd . C:\Users\atakan\Desktop\milpilsil\mult_ert_rtw\pil>if "" == "" ("D:\MATLAB\bin\win64\gmake" -f mult.mk all ) else ("D:\MATLAB\bin\win64\gmake" -f mult.mk ) "### Invoking postbuild tool "Binary Converter" ..." "C:/PROGRA~3/MATLAB/SUPPOR~1/R2020b/3P778C~1.INS/GNUARM~1.INS/win/bin/arm-none-eabi-objcopy" -O binary ./mult.elf ../../mult.bin "### Done invoking postbuild tool." "### Invoking postbuild tool "Hex Converter" ..." "C:/PROGRA~3/MATLAB/SUPPOR~1/R2020b/3P778C~1.INS/GNUARM~1.INS/win/bin/arm-none-eabi-objcopy" -O ihex ./mult.elf ../../mult.hex "### Done invoking postbuild tool." "### Invoking postbuild tool "Executable Size" ..." "C:/PROGRA~3/MATLAB/SUPPOR~1/R2020b/3P778C~1.INS/GNUARM~1.INS/win/bin/arm-none-eabi-size" ./mult.elf text data bss dec hex filename 16748 160 12016 28924 70fc ./mult.elf "### Done invoking postbuild tool." "### Successfully generated all binary outputs." C:\Users\atakan\Desktop\milpilsil\mult_ert_rtw\pil>exit 0 .### Starting application: 'mult_ert_rtw\pil\mult.elf' .### Started new OpenOCD process with PID 19356. .### Terminated OpenOCD process with PID 19356.
The timeout of 10 seconds for receiving data from the rtiostream interface has been exceeded. There might be multiple reasons for this communications failure. You should: (a) Check that the target hardware configuration is correct, for example, check that the byte ordering is correct. (b) Confirm that the target application is running on the target hardware. (c) Consider the possibility of application run-time failures (e.g. divide by zero exceptions, incorrect custom code integration, etc.). Note (c): To identify possible reasons for the run-time failure, consider using SIL, which supports signal handlers and debugging. If you cannot find a solution, consider using the method setTimeoutRecvSecs of rtw.connectivity.RtIOStreamHostCommunicator to increase the timeout value.
How can I fix this?


texts: Calculating thevenin voltage with two voltage supplies

texts: I can't seem to find out how to get the thevenin voltage with two parallell voltage sources. I have calculated thevenin resistance to be 2.67Ω. It is my understanding that I need to calculate the voltage between A and B. Could someone please help me out with this one.


texts: Is it possible to convert/copy/transfer my MULTISIM circuit into LTspice file?

texts:
Hello,
By any chance, if is there a way to convert/copy/transfer my MULTISIM circuit into LTspice.
Would appreciate a lot your responses
Thank you


texts: Choosing a controller/drive for a bare-glass SLCD

texts: I'm interested in playing with bare-glass SLCDs for low-power applications, so I picked up a few of these recently. It's four digit, seven segment, 1/4 duty, 1/3 bias SLCD with 12 pins. I'm unsure what controller or driver to look for to help run this thing, because I really don't know what to even look for in the datasheet. Any help would be appreciated. Through-hole would be great.


texts: How to write more than one page at once in Winbond W25Q32JV

texts:
I am using Eclipse IDE for firmware development. I am using Quectel MC60 module with Winbond W25Q32JV (4 MB memory). The thing is that I am able to read/write single page.

I am facing issue with multiple page writing at once. I have to write multiple pages at once since I had erased the sector (consists of 16 pages).
Before writing one page, I had to erase 1 sector.

General algorithm for writing:

main()
{
// read from memory address adr

// erase sector (16 pages)

// write at address adr
}

I want to utilize memory pages for optimum performance. Any help will be appreciated.

Thanks for your prompt response.
                                                                                My pseudocode  is like this:

char buff[256];

sector_erase(0);   // erase first 16 pages

memset(buff,7,sizeof(buff));

for(int addr=0;addr<16;addr++)
    {
    write_enable();
    page_program();
    spi_write(addr,buff);    // write page one by one and hence increment the address
    while(status_register);   // polling status register
    }


texts: What is the difference between VA and W for a relay

texts:
I am trying to choose a relay to control a compressor. The compressor alimentation is 230V (50Hz), the max intensity is 0.9A and the power needed is 130W.

Then I found two relays: the ALD112W and the GNDB-1A-E12VDC with Max switching current 5A and max switching voltage 250VAC.

So that seems ok but when I looked at the max switching power it is 1250VA, 90W.

Since W is the real power needed and VA is the complete power I don't understand why there is a difference for a relay which should just let the current pass or not.

Which one is important? 1250VA or 90W? Since the compressor is I think like a motor.


texts: Brushless DC Motor - Sensoreless Startup Algorithm

texts:
I am trying to achieve speed control of a sensorless Brushless dc motor (Back Emf method). Initially its speed is zero so Back emf is zero, so there will be no feedback, in that case what do i do?
 In my current implementation I can only hear a high pitch noise but no rotation.
 please help.
        I Hope this helps. As for the code, Im not sure. Could anybody help me out?


texts: where i can find allwinner library for eagle

texts: I work in a project using Allwinner a10 CPU and eagle software i did't find the library I already tried to searched in google and github many time for Allwinner a10 library for eagle software but I did't find any thing where i can find this library ?


texts:
I'm trying to troubleshoot a problem with my Creative Inspire T6100 speakers.
They seem to be known for volume control issues.
In any case, I'm trying to determine if the power adapter is working as expected.
In the label it reads "13.5V" as output, but I am measuring about 15V.
Would it be safe to assume that the adaptor is faulty? Or should the additional output not represent a problem?


texts:
EDIT: I am not removing the linked question and redoing the question.

How do you formulate an equation on a node with two voltage sources connected in it, regardless if it is a supernode or not?

(You may ignore the statements below this.)

Though this question has been answered here, I still have doubts in mind.

Consider the circuit below. In the linked question above, both voltage sources have the same value for voltage. The circuit below has 30 V and 20 V. Will it still be zero just like the one in the linked question? If not, how should you create the nodal equation for node 1? Usually, if there is only one voltage source connected to the node, and if it is connected to the ground, you just equate V to the value of voltage source. (Let's say below, if there is no 2 kΩ resistor below node 2, V1 = 30 V.)

An additional question as well. What if there are two voltage sources, but the other one is not independent but a VCVS or CCVS? How do you formulate the equation at that certain node with those branches connected?


texts:
What happens to STM32F407 ADC if i give it an input voltage higher than maximum VDDA that is mentioned in datasheet equals to 3.6 volts?

It will harm the micro?