texts: Today I was told that something was causing Transmission Loss and not Insertion Loss. Can someone clarify what these two phenomena are? I always thought they were the same thing expressed in dB or dB/m.


texts:
I'm working on a project where I locate an object using TDOA (Time Difference of Arrival) plus RSSI with trilateration method.
The object send a message to antennas near it.

The problem is I want to add accuracy on the estimation of the distance between the object and the antennas so I'm asking if there is any way to estimate that distance using SNR.
Is there a formula between SNR and distance ?

Thanks for your help !


texts: Is it possible to connect a NOT gate (74hc04) to connect two separate circuits in parallel?

texts: Say I am low on the number of IC, can I use the same not gate for two different connections in parallel in a breadboard? Will there be any interference like short circuits or unexpected behavior if I do this?


texts: What happens if I swap the power supplies on am OP-AMP?

texts:
I designed a simple audio amplifier - for learning purpose.
After getting PCBs made, I realized some critical errors and stupidities in my design.

One of the mistakes I made is that +12V and -12V are swapped (not to mention I shorted +12 to the inverting input of the op-amp).

After populating the components, I turned on the power supply. It wasn't getting warm or anything, so I plugged in my iPod. Then the OP-AMP and the PCB got really hot!

So now I am curious if my OP-AMP survived this ordeal. I am too afraid to find out by dropping the OP-AMP onto a redesigned PCB.


texts:
I am working with the DC-LVDT Omega 620-25

http://www.omega.com/pptst/LD620.html

Manual: http://www.omega.com/Manuals/manualpdf/M4345.pdf

Specs: http://www.omega.com/pressure/pdf/LD620.pdf

I am using the NI 9220 module on a compact DAQ for data acquisition. the module supports differential inputs and single ended mode.

NI 9220: http://www.ni.com/pdf/manuals/373920a_02.pdf

I am experience some trouble obtaining 3 digits of accuracy from the converted signal, the excitation voltage is 12.75 Volts (external adapter) and the reading is -5.9

Furthermore the second case was by using a single ended connection (as per the modules datasheet) single ended is achieved by connecting the signal - of the LVDT module to the COM input, I also placed a 100nF capacitor for noise filtering, I was able to get 2 digits of accuracy 1.12x.

Input is read with a continuous acquisition mode of 100 samples/second with a 500Hz frequency and a voltage range of -10 and 10 as device parameter options ( only differential mode is selectable)

In addition and since the LVDT is linear I should directly convert the voltage reading to distance but the output voltage is of different range
the datasheet states that for an lvdt of -d/2 and d/2 it should outputs a -5 and 5 V readings.

I double checked on the sensitivity formula mv/V/mm
Output Ripple: 0.02% FSO
LD620-25 ±25 (±1.0)inch
and with a range of -6 -> 6 the full LVDT range is (12V)
therefore is its of 0.0024 mv/V * 12.75(excitation) = 0.0306mm

Example used: http://tinyurl.com/hrcshow

but i didn't use that as for calibration I am considering the initial read voltage to be the 0 reference and then subtracting it from each reading!

1) What is the difference between using a single- ended and differential modes for a DC output? and how can I achieve better accuracy

2)where do I use the calculated sensitivity and did I get the calculation correctly?

3)how can I eliminate additional noise (AC noise) that is affecting my measurement and what should I take into consideration for designing a filter and choosing it's type

when disconnecting the LVDT excitation voltage the modules outputs uV values that varies. considering the copper wire acts a receiver and generating additional noise I place the 100nF capacitor between the signal + and signal - terminals.

In addition, I am going to design a circuit to level shift the output voltage from -6 6 to 0 - 12 and make it a single ended output and connecting it to an arduino or a PIC (is it a good idea)?

Thank you in advance! I appreciate the help


texts:
I would like a little insight on choosing a Mosfet for a hotwire cutter. The wire runs 12v @ 2A

I am planning on using a 555 PWM circuit to control the temp on the wire. I plan to use the PWM signal through a mosfet to do this.

I have never used a mosfet for this before. If there is one that would run fine with out a heat sink that would be awesome as the whole project has to be as low cost as possible.

If anyone could recommend one or two I will have a look at the specs. I can post a circuit diagram if needed, not quite complete yet.


texts:
I'm following a tutorial that use a MC14543B chip.
The chip is defined as "Bcd-to-7 Segment Latch/decoder/driver"
Datasheet is here: http://www.digchip.com/datasheets/parts/datasheet/343/MC14543B-pdf.php
Any advice ? What do you use to control 7 segments from the status of only 4 pins ?
Edit:
I was asked for a Schema where the BCD to 7 segment is being used:

(source: siteduzero.com)


texts: Why is resistor in parallel with capacitor needed in capacitor bank?

texts: Capacitor bank in power supply compensates for when input voltage is shortly disconnected (50ms lets say). Do capacitors in this setup (between input and the output of power supply), get initially charged and then remain charged until input power gets disconnected? After that, do capacitors discharge their energy at the output load. If the output load is there to discharge capacitors, why would resistors in parallel to capacitor bank be needed?


texts: Measure resistance of resistor in cirucit

texts:
How do I measure accurately with a multimeter the resistance of a resistor that is already soldered as part of a circuit?
In a simple transistor as a switch circuit, I noticed that when I tried to measure the collector resistor I got a value of about 170KOhms, but I knew that was incorrect, so I took the resistor out and measured again and I got the correct value, so that got me curious, how can I measure the resistance of a resistor that is already in a circuit and know for sure that it is the resistor I am measuring and not the rest of the circuit.


texts:
I'm working on a PCB powered solely by a battery. No charging on the device itself.
I have a question about grounding.

Can I connect -BATT to the global ground plane of the PCB? In schematics for the DW01-G battery protection IC, it has two seperate connections for GND and -BATT(like in the diagram below) I'm wondering, can't I just join these together?

TLDR: Can GND and -BATT be connected together? If so, why do diagrams have it seperate.


texts:
I need to drive LEDs in LCD backlighting. My LED are in this circuit:

The backlight needs a current of 700 mA at 9 V. What driver should I use for control? According to the current peak calculation is 1.5A at 5V supply power at 79% efficiency of driver.

Can I use the circuit LD41 from STMicroelectronic?

On board I have the power branches 5V and 24V.


texts: Given the diagram, where do I add/replace a larger capacitor for continued power while bike is stopped?

texts:
Following the circuit diagram, included as an image in this guide, where do I replace/add a larger capacitor for continued power while the bike is stopped?

My guess is that it should replace the capacitor between the rectifier and the voltage regulator, but I'd like some input from someone who knows. I'm planning to insert a 2200uF capacitor.


texts: What does it mean to establish the state of the internal node in CMOS circuit?

texts:
This is the NAND circuit and the 'int' is the internal node of the circuit.

It is seen that A = B= 0→ 1 gives the worst delay in the below table. What does it mean to establish the state of the internal node as stated in the text below.
It is not clear to me.


texts:
i'm sorry for asking a stupid question, but currently i'm making a simple mp3 player with yx5200-24ss chip. Please read the attached schematic below:

Is it alright if i'm not using pin 15 and pin 16 (adkey1 and adkey2) as shown in the schematic above? For i plan on using mcu to control the ic. Will it working properly without a 22k resistor between vdd io and the addkeys pins?

By the way this ic used in DFPlayer Mini

thanks.


texts: Electronics Newbie - How can I mute speakers when 3.5mm is plugged into female jack? (with volume control)

texts:
So I'm a recent newbie to the world of electronics and have been working on a personal project using the Pi Zero W but I've reached a snag when it comes to sorting out audio.

I have 2 problems I'm trying to figure out:

1) Mute speakers when 3.5mm male is in female jack and vice versa.
2) Control the volume for both speakers and 3.5mm.

Now I've seen tutorials online on how to create an amp op circuit using a 3.5mm plug for amplifying a internal speaker but seen nothing so far online in regards to using a 3.5mm jack.

I was told by an electronics buddy I could use an audio switching MOSFET and to look at differential OP amps as circuit boards but still alot of it confuses me.

At current my project is using a piezo speaker with the goal of simply playing single notes. Although for other parts of my project I will be using sound files and want to also eliminate any loss of sound quality when transferred between speaker/3.5mm.

Any help will be appreciated if able to help. Remember I'm newbie to this so apologies if I don't pick up answer straight away and know exactly what you're talking about.

Edit: I see answers I can understand the 5pin jack and the pins shorting out stuff. What I'm more concerned about is forming the circuit itself. As in are any helpful videos or images that you could point me? Cause there's 1 thing saying it but to be actually able to see it then makes all the better sense to myself.

Edit 2:

I think I've managed to understand it all correctly and following google searches as well got the circuit wired for potentiometer and speaker but could do with a checking with to see if I've got it all right (See image below).


texts:
The above image is from my class notes. I am not able to understand the concept of GMD and GMR calculation.
While practicing, I came across the below problem

Now I am not able to understand how the above formulae can be used to solve this problem. Please help me with this concept.
EDIT 1: I was expecting the solution to be like
Taking 1 as a phase and 2,3 as another phase
Mutual GMD = (D12 x D13)^(1/2) = (2 x 4)^(1/2) = 2.828


texts: Solution for 20Vpp output waveform opamp

texts:
I am planning to design an opamp circuit from 2Vpp to 40 Vpp for frequency rage 0-5MHz as shown in the Figure:

The problem I am facing right now is in the market, there is not an opamp chip that can amplify up to 40Vpp, because the Vmax total voltage supply from V+ to V- for opamp at 5MHz is around  26V, that means V+ =18V only, therefore my output amplitude will be clipped off when V=16V, so how to achieve it? Any possible solution can recommend?


texts: Can a metal pipe shield wiring against EMP during a nearby lightning strike?

texts: I have a building which regularly experiences nearby lightning strikes. The backup diesel generator is located 10 meters away from the building. Can induced currents from the EMP be reduced within the wires connecting the building to the generator, if they were made to run through a grounded metal pipe? The pipe will run above ground.


texts:
I have a DB25 I/O connector, thru-hole.  The pins connect to an SMT MCU, which I want to protect from ESD, specifically IEC 61000-4-2.  I want to use SMT Zener diodes to protect the pins.

I am considering various layouts.  I imagine the optimal layout would have the diodes between the DB25 and the MCU.  In this way, an ESD event can be shunted to ground before it gets to the MCU

MCU <-> Diodes <-> DB25

However, I would like to take advantage of the thru-holes in the DB25 to simplify routing and reduce the number of vias that I would need.  However, in doing so, the diodes will end up on the "other side" of the DB25.

MCU <-> DB25 <-> Diodes

Is this a bad idea?  I'm slightly concerned about whether a sufficiently fast ESD strike could "split up" and reach the MCU before the diodes begin fully conducting.

If this is the case, would it be mitigated if the MCU <-> DB25 traces were run on bottom-layer, while DB25 <-> Diodes traces were on the top layer?  Would the added vias between the MCU and DB25 encourage the ESD current to go through the diode instead?


texts: PSU Series and Parallel Tracking Mode, Current Limit Behavior

texts:
I'm designing a training course for use of the electronics lab equipment at the local makerspace. We have a HY3005F-3 dual-channel DC power supply, and I scanned and posted the manual here. I'm writing up instructions on how to use it, and I'm a bit rusty / the manual is not super clear about configuring the current limit for the PSU in Series and Parallel Tracking modes.

The manual says that in Series Mode you basically get this topology:

It then goes on to say the procedure is to:

Set the Slave current adjust knob to its maximum clockwise position.
Then set the Master Voltage and Current [as described for Independent mode].

It goes on to briefly describe two "use cases" for this mode - essentially by my interpretation a "+/-X" bipolar use case; and a 0 to +2X single-ended use case.

So what exactly does the current limit you set in this manner apply to? My guess would be that it restricts more than the current limit from flowing into (or out of) any of the three terminals depicted in my schematic, and that it does so by going into constant-current mode by reducing both the Master and Slave supply voltages to the point where the current is in bounds of the set limit.

In Parallel Tracking mode the manual makes the statement "The output current is twice the set master current while the output voltage is the same as the master setting value." It then describes the procedure of setting the current limit as follows:

Set both the Slave current and voltage adjust knobs to their maximum clockwise position.
Then set the Master Voltage and Current [as described for Independent mode].

So does that mean if I follow that procedure for Parallel Mode, and set the current limit to X Amps, the actual current limit set will be 2X Amps?

So what is incorrect and what is correct in my exposition above? Sorry I hate to ask an "am I right?" type of question, but perhaps this also gives someone the opportunity to expound upon the most common utility of Series Tracking mode that I might convey that wisdom on to my colleagues.


texts:
So this query is related to DC synthesis compiler for digital design.

I have a hierarchical VHDL design, with each entity having "Generics". When elaborating the design, should I add the -parameters [name_of_params] only to the top level design or to each entity under it and specify the individual params?

Here's a link to my code snippet.

PS: if it's not clear, let me know; I will upload a screenshot then!


texts: One crystal oscillator for multiple clock inputs PCB tracks topology

texts:
When sharing a crystal oscillator output to multiple clock inputs, what should the oscillator output PCB tracks topology be ? Should they go from the oscillator output to one clock input to the next clock input and so on (chaining) ? Should they all start at the oscillator output and connect independently to the clock inputs (star) ? Is it unimportant ?

Thank you !


texts: What is severity level in AIS-140 document?

texts:
We are working on designing a PCB which is supposed to pass the AIS - 140 Shock Test. My board has a relay, which is an electro-mechanical component and is of a major concern in the shock test.
As per the AIS - 140 specifications shock test is described as
"Shock test is performed to provide a degree of confidence that the device can physically and functionally withstand the relatively infrequent, non-repetitive shocks encountered in transportation environments.This test provides an assessment of the effect of the shocks on the performance of the device. The test shall be performed as per IS 9000-part 7 – 2006. Severity Level = 15g, Impact duration = 11ms, Impact Type = Half sine, Total number of impact = 9 (3 on each axis)"
And the acceptance criteria is :
"Device after the shock test shall be required to meet Class A operation."
where class A is "All functions of the device/system perform as designed during and after the test"
Now, my doubt is what does Severity Level = 15g signify ?
As per the mentioned IS 9000 Part 7 - 2006 document, severity level is specified in terms of Joules

Also, the datasheet of the relay selected mentions the following :
Shock Resistance (Reliable Operation) = Min. 98m/s^2
Shock Resistance (Destruction Operation) = Min. 980m/s^2
Wanted to know if the relay selected will pass the shock test mentioned as per AIS-140 Document?


texts: Which of the following motors best suit as a wind generator?

texts:
I'm watching some brushless outrunners with low kv as a generator for a simple wind turbine that I'm going to build soon. It might not be a scale or fully useful turbine, because I want to build it for testing and prototype purposes for now; I will test it with a fan(s) probably, however I want it to be as useful as possible.
I have found the motors that are linked below:

1) Turnigy CA80-80 Brushless Outrunner

2) Turnigy Aerodrive SK3 - 6374

3) Turnigy RotoMax50

4) Turnigy RotoMax80

5) Turnigy RotoMax100

6) Turnigy RotoMax150

As you see there are lots of details rather than just kv and I`m not such educated to understand these all. Could you clarify:

(a) which of these is the best as a wind generator? why?

(b) which of these is the best for price? why?

(c) and do you recommend something else than of these?

If you ask me how much output I need, I don't know, I would be additionally thankful if you could clarify how much these things can produce, what is the optimal load, and other  information you think is useful.


texts: Does this circuit include two level logic circuits?

texts:
I made the circuit below from the logic expression below.

A'B' + A'C' + A'D + ABC

But, I was told to consider adding two level AND-OR and NAND-NAND logic circuits. I think the circuit below has them, but I'm not sure. Can I get a confirmation if I'm right? Thanks in advance.


texts: Will the charging current decrease due to a higher input resistance?

texts:
I am trying to design a board with USB powered linear battery charger IC charging a 3.7v Li-ion battery. I am concerning about the the relationship between charging path resistance and the maximum charging current. The overall resistance include: USB cable resistance; USB connector to the actual USB input pin on the charger IC PCB trace resistance; I am also consider to add a OVP IC which additionally contributes about 200mOhm.
From my understanding of linear charger, the maximum charging current(in constant current charging) will not decrease until the pass transistor saturates. So I think if I leave a voltage more than 0.3v for the pass transistor, the charging current will not be influenced by the input resistance.

If the transition voltage between constant current and constant voltage for the battery is 4.1v, the maximum charging current is
(5v - 4.1v - 0.3v)/(Rcable + Rtrace + Rovp).

Is my understanding right?


texts:
In the circuit I need to find out equivalence Resistance.

I have applied the Kirchhoff theorem and  but these  look too broad and might take too much time to solve. Is there any easy way to solve it?>

EDIT:
So if the vertical resistor doesn't apply any affect to the voltage then the equivalent resistance will be,
$$1/(R_e)=1/2R+1/2R+1/2R$$
That means
$$R_e=2/3R$$
. Is it right?? but the question is why the vertical resistor is not applying voltage changes to the circuit??? Are they acting as only voltage divisor, nothing else?


texts: Programming of Microcontrollers and other peripherals

texts:
This is a question based on the theory which I am reading and related to one design which I am trying to understand section by section

We are having microcontrollers and some peripherals are connected to it.

Microcontroller: https://www.nxp.com/docs/en/data-sheet/MPC5606S.pdf

EEPROM (16Kb): https://www.onsemi.com/pub/Collateral/CAT24C01-D.PDF

SPI Flash (256Mb): http://www.cypress.com/file/448601/download

The microcontroller is connected to the EEPROM and SPI Flash.

Please check if my understanding is correct :

The software code for the microcontroller needs to stored in a separate non-volatile memory. So, that's why we are storing the boot code in the EEPROM which is a non volatile memory. And we have TFT data which needs to be displayed present in the SPI flash.

Forgive me if my question is too basic.

Once we write the software code for the microcontroller in our PC, how do we load it into the microcontroller?
How is the TFT information (transferred to) stored in the SPI Flash initially?
Does microcontroller have any sort of bootcode initially?

How are these done using Hardware?

Please explain in simple terms.

I just want to know how the software for these codes get inside the hardware (ICs) before the board starts to operate.

Thank you all.


texts: Why do USB data cables have 5 wires, what is the use of shielding wire?

texts:
I have always been curious about the 5th wire(aka shield wire) in USB cables. What is its purpose? Does it anyhow affect charging speed for mobiles or data transfer?
I do know that it carries the signal GND as well, but why add another wire for it inside the cable.

Does it have anything to do with external field interferences?


texts: Replace switching diode with MOSFET for lower voltage drop in charge pump?

texts:
I have seen reverse voltage protection circuits that use a pmos instead of a diode so that there is minimal power loss and voltage drop in that sector of the circuit.

I want to make a charge pump for logic level MOSFETs, but if I only have 5v as a supply, my charge pump will only charge the capacitor to around 4.3v. Is a pmos suitable for fast switching applications in a charge pump?

Images from Hackaday and Circuitdigest.


texts: Why is NOR memory considered XIP, and NAND memory is not?

texts:
I've been reading up on NOR and NAND memories in search of an answer as to why exactly is NOR a XIP (eXecute In Place), and NAND is not. While both of the links were extremely informative and well-written, neither explicitly satisfied my curiosity.

I think I understand the basic pros and cons of both kinds. The way I see it, NOR memory is suitable for program storage, instead of data storage, because it has fast read times, and horrendously slow write/erase times. Clear so far. Also, NOR offers true random access (due to the NOR gates, which are essentially parallel and not serial, if I understood it correctly), as opposed to NAND, which typically works on the level of words, serially, not individual bits.

This made me think that the XIP part is somehow due to the ability to access every individual bit, NOR being random. I am, however, not fully convinced this is so. Is that right, or am I spouting nonsense?

A followup if it indeed is so - I've gotten the impression that NAND actually can be implemented in a way that achieves random access (although there is no real reason to do this, AFAIK). Could XIP theoretically then also be achieved with such NAND memory?


texts:
I have made my own PCB for a project which carry AC supply, and I want to know all about it: If due to moisture it may short out or not, and how to protect it from moisture.

I have seen UV curable solder mask, but I didn't find it in any store, and I have got to some shops, they have something spray or transparent liquid which provides protection against moisture but it was costly. I can't buy it for just 3-4 PCBs.

Please suggest me any other cheap way to provide a protective layer. For a moment I thought to apply oil paint or hot glue on it, but I didn't know if it will work.


texts: Difference amplifier with potentiometer on input

texts:
I've wired this circuit :

simulate this circuit – Schematic created using CircuitLab

When Vin- not connected to R1 I get Vin+ - Vin- in interval [0, 0.5]V when moving potentiometer
After, if I connect Vin- to R1 I get Vin+ - Vin- in interval [0, 1.8]V when moving potentiometer
Vout is in range [1, 3]V

Why does Vin- range change when I connect it to inverting input?

lah


texts:
It seems that ADPCM is all but non-existant anymore. But I'd like to use this to compress six high-quality audio channels into a smaller bit-stream with little overhead.

There seems to be a dsPIC G.726A Speech Encoding/Decoding Library and accompanying User's Guide, however:

These files are for 8kHz sample rate; desired is 40kHz.
I can't find these files anywhere. (And think they were for the old MPLAB.)

This is compounded by the intended function of this dsPIC:

Acquire six samples from SPI1 device (40kHz rate, 16-bit)
ADPCM the six samples from 16-bit to 4-bit
Multiplex these 24 bits into 3 bytes, queue/wait for SPI2
Send to SPI2 device (both 8MHz SPI)

Even at 64MHz clock, I have no clue as to whether this dsPIC has enough horsepower to accomplish all of this. The user's guide above in table 4-4 reads that the "computational speed [of the] encode function [is] 7MIPS" which is ambiguous for many reasons.

Application note AN643 shows some generic C code for implementing ADPCM compression, but nothing tailored to dsPIC. The dsPIC libraries for dsPIC33E which are available, are all precompiled for low sample-rate telephony applications.

Can anyone give insight into a direction to proceed? Is this futile with a single dsPIC? Is hacking dsPIC assembler the only way? Is there a better way to approach this application?


texts: Can I connect my ADMP401 straight to my computer's microphone jack?

texts: So I'm looking to get a bit more value out of this little 'ol microphone I have. It has a Vcc, GND, and an analog data port on the breakout board. Could I splice a 3.5 mm jack wire and connect the microphone to my computer's microphone port to record the sound in Audacity? What voltage does the 3.5 mm jack use? Has anyone tried doing this with an electret microphone?


texts: Internally compensated opamp for 5V/V or more

texts:
I am using opamp for some signal conditioning circuit. I want to use opamp as voltage follower. It is mentioned in the Opamp datasheet that opamp is internallly compensated for 5/5V, 10V/V, or more etc.
I have read the concept of internal compensation of opamp for unity gain. I am doubtful about internal compensation for 5 or 10 gain.
Does it mean that I have to externally set at least 5 gain with feedback resistor? i can't connect in follower configuration?
or does it mean even if i connect in voltage follower configuration (inverting terminal to output) with unity gain, Vout=5*Vin?


texts: In the context of a differentiator circuit, what is a “current-sensing resistor”?

texts:
I’m reading through The Art of Electronics and am puzzled by the use of the term “current-sensing resistor” as it pertains to differentiator circuits. In the above figure, the author explains that a perfect differentiator could be made from a capacitor alone, although the current through the capacitor could not be used as an output. So, he says a “current-sensing resistor” must be added. My questions are:

1) What does the term “current-sensing” mean in this context?

2) Why is the resistor even necessary? I’m having trouble understanding intuitively why this is.


texts: Can someone help me identify the is connector?

texts:
I'm repairing an old coffee machine and one of the wires came out the its connector. I'd like to order the connector and the proper crimps to repair it but I'm unsure of which type/size to order.
Here are some pictures:


texts: Parallel LED not achieving expected current from 18650 battery pack and Boost converter

texts:
This is kinda a follow up to a previous question I asked here: Parallel 18650 battery pack voltage not stepping-up with Boost converter. Why?

I have now added the correct boost converter to my 20 LED and I am able to achieve higher voltages, however when I measure the current from the output of the booster converter and the wired LEDs, I am not getting the expected current, thus not getting the full power out of it.

My setup is:

20 x LED (12V, 1050ma) (Parallel circuit)
6P 18650 battery pack (Samsung 25R 3.7V, 2500mah)
LM2587 Boost converter - 5A (https://www.banggood.com/LM2587-DC-DC-Boost-Converter-5A-3-30V-Step-Up-to-4-35V-Power-Supply-Module-p-1135387.html?cur_warehouse=CN)

So, if I am correct, my LEDs (as it's laid out) should consume 12V at 21A?
And my battery pack should supply 3.7V at 15A?
Correct me if I am wrong.

I have no intentions of delivering the full 15A or 21A (the latter being impossible) but at 12V at 4A or 10V at 5A.
However, my current readings are always giving me 0.7A on my multimeter!

Does anyone know what could be going wrong here?


texts: Should I add insulation to lithium ion battery

texts:
I have purchased a 36v 10ah lithium ion battery for use with an electric bike.

I live in rural Australia where it gets very hot in summer and fairly cold in winter. I considered insulating the battery with silver tape to reduce the battery's exposure to the weather.

I then read that using the battery makes it hot and I thought insulating the battery with silver tape could do more harm than good.

Should this battery be insulated?

Thanks

EDIT

This is the datasheet for the battery's cells (no datasheet for battery)

This is the battery on AliExpress

This is the tape


texts: Pin Arrangement which one should i follow?

texts:
I have 2 different arrangement of 7448 IC's pins, and I'm not sure which one I should follow. The two different pin arrangements I found for the IC are:

www.alldatasheet.com/datasheet-pdf/pdf/247381/RENESAS/HD74LS48P.html
www.alldatasheet.com/datasheet-pdf/pdf/27434/TI/SN74LS48N.html

The circuit I'm trying to make is making is diagrammed here. According to this circuit diagram it should be connected in different way.  I have two questions:

Should I use the datasheet I found on alldatasheet or the one I have?
Can I  mix HD74lS48p and SN74lS48n?


texts: Driving a Common Anode RGB LED Using a uC

texts:
I have an RGB LED, APHF1608LSEEQBDZGKC, (Datasheet) which is common anode. The blue and green diodes both have a forward voltage of 2.65V while the red has a forward voltage of 1.8V. I want to minimize component count while driving this LED with the TI CC2640R2F embedded MCU (Datasheet). My circuit is running off of a 3V regulator and my plan is to use the analog GPIO pins on the MCU to control the LED.

The first problem is that the current would be flowing into the GPIO pins.

The second problem is that 3V is higher than the forward voltages of the LEDs.

Therefore, my question, would it be possible to, for the green diode, feed 3V into the common anode, and then connect the cathode to an analog GPIO pin set to .35V thereby creating a 2.65V drop over the LED? I am trying to minimize component count and current draw, any suggestions are welcome.


texts: Long tailed pair not working to compare signals from 2 LDRs

texts:
I've been trying to compare my signals from 2 LDRs to feed into Arduino's ADC.
However I can not get any gain from my differential amplification.

The problem comes when I have high resistance from 1 of the LDR's in the dark (1 MΩ).
There's not enough current flowing through the base and it always makes the transistor work in forward-biased.
I tried adding a voltage divider to bias the voltage to the base, but I am still having trouble.
I want to amplify the difference because between midday and full sunlight there is not much difference in resistance and I would like a more accurate reading when using the ADC.
Also would like to add that I'm not allowed to use op-amps for this circuit.


texts: RC Car mounted Raspberry Pi runs out of juice

texts:
I'm trying to make a Tamiya Blackfoot RC car run on a Raspberry Pi.

I've written a small C program for controlling the servo and the ESC/motor with a wireless gamepad. Everything is working fine when RasPi is getting its power from a separate power source (mains), but with the RC battery some problems occur.

When RasPi is connected to the RC battery (via 3A/5V UBEC) the servo control works but I have to be very careful when controlling the motor. If I accelerate too fast, at least one of the following will happen:

WiFi dongle can't get enough power
Joystick receiver can't get enough power
Raspberry Pi reboots

I tried adding a 2200 μF electrolytic capacitor to prevent the brownouts, but it didn't seem to do the trick. I'm not (yet) very good with electronics so can you please tell me if there's anything to do to make the Raspberry car run without a second battery?

Here's a picture of the current setup. Please note that the voltage regulator is actually a 3A/5V UBEC, the resistors are 1 kΩ each, the cap is 2200 μF, and the motor controller is the closest to ESC (TEU-104BK) I could find.

UPDATE:

Thank you for your attention. I feel so stupid.. I forgot the 7.2V connection from the battery to the ESC from the image. Updated the image.

ESC (TEU-104BK)

Input voltage: 6.6-7.2V
Max. continuous current (FET spec): Forward 60A

Motor (RS-540SH-7520)

Operating range: 4.8~7.2 V
Nominal voltage: 7.2 V
Current no load: 2.4 A
Current at maximum efficiency: 13.0 A
Output at maximum efficiency: 63.2 W
Current stall: 70.0 A

Servo (Tower Pro MG995)

Operating voltage: 4.8~7.2 V
Current Drain (4.8 V): 8.8 mA/idle and 350 mA no load operating
Current Drain (6.0 V): 9.1 mA/idle and 450 mA no load operating

Battery (HPI Racing Plazma)

Voltage: 7.2 V
Capacity: 3300 mAh
Cells: 6
Brand new (I've got two of these)

Raspberry Pi GPIO

Output voltage: 3.3 V
Max current for pins 18 & 23: 16 mA each


texts: Required to use a DB9 connector to pass DC to unit requiring 12V/5A supply. An easy way to do that is using a DB-9 to Terminal Block adapter. But most DB-9 to TB adapters I see have 3 A or less current rating per pin. How can use such adapter to make it pass a 12V/5A stably?


texts: Output CLOCK signal to GPIO pin of CYCLONE IV E

texts:
I am new to FPGA and I am trying to send a CLOCK signal as an output of a GPIO pin of an Altera Cyclone IV E. I first made a program:

module CLOCK_out (input CLOCK_50, output CLOCK_pin);
      assign CLOCK_pin = CLOCK_50;

endmodule

It just sends out the default 50 MHz clock signal of the DE0-Nano Board to a GPIO pin. This is a success. However, when I viewed the signal with an oscilloscope, what I have is a 50MHz sine wave (see attached picture). I feel like I produced the wrong signal because I am expecting a square wave instead . I don't know where I am wrong. I am using 3.3V LVTTL standard for the IO. Is there something wrong with what I have done or is the output really a sine wave after all?

I need help. Thanks in Advance


texts: STM32 L1 Bootloader: how to set the reset vector

texts:
I am trying to program a STM32 L1(51C8Ux) via the standard bootloader and when I do the memory gets written to, but the code doesn't execute (after reset that is).  I assume as part of the memory erase, I have overwritten the reset vector.  Where does the reset vector reside and what am I supposed to write to it?

I have been referencing RM0038 (Reference manual) and AN3155 (Bootloader command set).


texts: Transformer dimensioning for SMPS (not the Aw Ae way)

texts:
There's a lot of documents that talks about dimensioning of the transformer for a SMPS power supply (in this case one quadrant only is not of my interest).

this site cites the following:

  The main constraint in all cases (except for saturable inductors) is that peak magnetic
  flux density Bmax should not approach the core material's saturation flux value Bsat.

(more)

  Contrary to popular misconception, Bmax does not depend on the magnetic material
  properties or air gaps. It does not depend on the transferred power neither. However,
  for thermal reasons, we have to limit ohmic losses in the wires. Most textbooks
  provide  formulas for estimation of the core size based on the product of magnetic cross-section
  area by the window area available for the winding. Unfortunately, this method is not
  very helpful because these formulas are based on pretty much arbitrary selection of
  current density and on an assumption of a certain window utilization (fill) factor.

So, I calculated the Bmax for my project, and it gives-me similar results to that of poweresim.com. But with the AwAe method it requires more than 4 times the core size!

Anyway, the Bmax formula being close to the results, it does not have the current included in the formula. So that any power (respecting the Vpk and f in the formula) could be used with the same Ae transformer.

Is the core size not dependent on H, just B? That is, having enough space for windings for the projected currents/potentials and getting Bmax below saturation Bsat, and dis-considering hysteresis, eddy-current losses, what should I consider?

If not what should I consider then? If I try to calculate H, it will give-me values really above saturation (from B-H curve), for near most materials, so I think thats wrong.


texts:
Sirs,

I am not able to understand why Proportional controller introduces offset.Please consider follwing paragraph I found on internet, credit to **

http://blog.opticontrols.com/archives/344

**, regarding offset error of Proportional only controller -

" If the operator should increase the flow out of the tank, the tank level will begin to decrease due to the imbalance between inflow and outflow. While the tank level decreases, the error increases and our proportional controller increases the controller output proportional to this error. Consequently, the valve controlling the flow into the tank opens wider and more water flows into the tank.

As the level continues to decrease, the valve continues to open until it gets to a point where the inflow again matches the outflow. At this point the tank level (and error) will remain constant. Because the error remains constant our P-controller will keep its output constant and the control valve will hold its position. The system now remains at balance, but the tank level remains below its set point. This residual sustained error is called Offset."

I believe that measured variable here is level of liquid in the tank and not the outflow.
Considering the bold statements in above paragraph, my question is why the valve will open only unitill inflow matches outflow? Shouldn't it open till the level measured equals setpoint? Then why the offset should come into pitcutre?


texts: I am using 4500 RPM motor.To be specific,this is the motor I am using https://www.robomart.com/4500-rpm-high-torque-dc-motor. I am using Cytron MD10C motor driver to drive it.The PWM source is Raspberry pi.What is the range of frequency for PWM that I can use for this setup? Both the motor driver and the motor gets heated when a little amount of load is given.I have tried 50 to 300 Hz.


texts: Could some please help me understand why D2 is on and not D1 on a) and why is D1 is on and not D2 for b). This is for ideal diodes


texts:
Some basic questions concerning Stepper motor with geared head/geared box.

What is the meaning the reduction 1:56 (1/56) or 1:100 (1/100) or 18/1? According to some charts:

How can i know (calculate) the RPM from the reduction ratio? Why there are more reduction for the same Holding torqoue (eg.: J57HB56-03 Holding torque = 0,9 Nm but the reduction can be 1:3 or 1:5)? Does it have affect on the motor life long if i use great reduction (1:100) to increase the torqoue from smal stepper motor? I mean that motor life wil be shorter.

Thank you:
Palko


texts: Monostable multivibrator with NAND gates

texts:
I would understand the behavior of the V_C potential in this circuit. The IN-M voltage is a pulse wave with 5% duty cycle. I think that it works in this way:

When the IN-M is HIGH the NAND 1's output is LOW so no matter how the NAND 3's output is, the NAND 2 output is HIGH.
At this point the charging of capacitor C1 starts and V_C potential is initially HIGH and than it decreases exponentially.
When the IN-M voltage becomes LOW and NAND 1's output is HIGH it happens that NAND 2's output is HIGH untill V_C potential goes below a treshold and consequently NAND 3's output becomes HIGH.
At this point the V_C potential becomes LOW (because there is a negative charge on the "right" plate of the capacitor) and the discharging of capacitor C1 starts at first through the diode D1 and than through the resistor R1.

I posted a screenshot of the oscilloscope with V_C and V_in traces. The zero potential level is indicated by the arrows.

I can't understand why the V_C potential during the discharging of the capacitor tends to a potential level different from zero as if asymptotically there was a current flowing through the resistor R1.


texts: Confusion regarding Timing Diagram of 8085 microprocessor

texts:
When do the transistions actually occur? I mean do the various registers used in 8085 are edge-triggered or level-triggered? Say, for example, The address value stored in Program Counter is passed on to the address bus but when? At the falling edge , rising edge or level triggered??

Why do we make read signal low for two clock cycles? Why not one?


texts: Risks associated with water in a powered-off circuit

texts:
I think I understand fairly well by now why one wouldn't want tap water to get in contact with an electric circuit as it is conductive.
However, assuming the circuit will dry out completely before it is turned on, are there any risks for the circuit associated with having some tap water splash on it while it is powered off?


texts: Blocking current from Backup battery (3x1.5V=4.5V) when powerbank (5V) is turned on my timer switch

texts:
I'd like to power cycle a RaspberryPi0 each 1h. I plan to use a TPl5110 for this, which can be powered by around 2.5-5.5V. I want to deliver 5V to the Vdd-Pin using a powerbank. However, once the RPI0 sends the done signal to the TPL5110-IC, too little current (<50mA) is drawn from the powerbank, which shuts the powerbank off.
Thus, I am thinking of using a Backup-Battery with 3x1.5V AA (alkaline) batteries to keep the TPL5110 powered on all the time.
Will it work as simple as adding a standard silicon diode after the 3x1.5V backup batteries, as sketched here:

I want to avoid current flowing from the backup battery to the RPI0 if it is powered on (at least as much as possible to avoid draining the backup battery low).
EDIT: my requirements are different from this question: how to switch to backup battery when power fail? since I do not just want to use a diode with forward voltage drop all the time since it consumes too much power for my application.
Thank you!


texts:
why there are two crystal oscillators connected in parallel in the circuit above? i am familiar with the configuration of Q2( look at the schematic) but what is the purpose of Q3? do i really need to implement it? if yes, why?

the chip is CC430F5133. datasheet


texts:
I am trying to communicate to SIM900 with PIC18F2520. I am able to send AT commands using  UART but I also want to receive its response like OK or ERROR.

Following is the code for RX interrupt

#pragma code rx_interrupt = 0x8
void rx_int(void)
{
  _asm goto rx_handler _endasm
}
#pragma code
#pragma interrupt rx_handler
void rx_handler(void)
{
  while (!DataRdyUSART());   //if data is ready to receive
  for(k=0;k<=20;k++)
  {

    Rx[k] = getcUSART();    //read a byte from UART

  }
  UARTSend("We have read everything");   //I have a put a breakpoint here
  if(strstr(Rx,"OK") != NULL)
  {
    UARTSend("OK received"\n);
  }

   PIR1bits.RCIF = 0;   //Clear the interrupt flag

}

Above is the code I am using for receiving data from SIM900. In the debug mode, I send UARTSend("AT\r");. I have a put a breakpoint at UARTSend("We have read everything");. At this line, I check for the Rx buffer in variable but it doesnt have OK instead it has few random chars while on the terminal I am getting proper response.

So how to read response from SIM900. The approach I am using it correct or not.Please help.


texts: STM32F04xx UART - Implement input rejection for strings longer than 2 bytes

texts:
I am trying to implement input validation on the STM32 side. I am hoping to allow a string in the form "x\n" where "x" can be any character.

To receive a changing number of bytes I have implemented this in USART1_IRQHandler

void USART1_IRQHandler(void)
{
    if((USART1->ISR & USART_ISR_RXNE) != RESET) {
        if((1+RX_BUFFER_POS) < RX_BUFFER_SIZE) {
            UART_Buffer[1+RX_BUFFER_POS++] = USART1->RDR; // reading from DR resets RXNE flag, no need to manually clear it!
    }
  }
  HAL_UART_IRQHandler(&huart1);
}

And in the main while loop of the program

if((RX_BUFFER_POS + 1) >= 2) {
  if(UART_Buffer[1] == 0x0A && !(UART_Buffer[2])) {
    HAL_UART_Transmit_IT(&huart1, (uint8_t*)OK_BUFFER, OKBUFFERSIZE);
  } else {
    UART_Buffer[2] = 0;
    RX_BUFFER_POS = -1;
    HAL_UART_Transmit_IT(&huart1, (uint8_t*)BAD_BUFFER, BADBUFFERSIZE);
  }
RX_BUFFER_POS = -1;
}

The code correctly rejects an invalid character string, I use "00\n" as an example, the first time. After that all strings are rejected, including a "valid" ("x\n") string.

I did some debugging, and found that after an incorrect string, RX_BUFFER_POS was not being reset to -1, instead it stuck at 0. What is the cause of this? I also found that if I added a 1ms delay to the main while loop, the problem was fixed. This makes me suspect that some sort of race condition is occuring.

A side note, I found a way to fix any character being rejected. If I send a string of length 7, with "\n" being the last character the rejection will work once more. When I send the string I receive "BAD" and also "OK".

My question is why is RX_BUFF_POS not being reset to -1 when an incorrect string is received? Also, as there seems to be a race condition occuring, how can I track down the cause of this?


texts: Implementing led lighting with SR-ZG9101FA-RGBW

texts:
So I have this device: SR-ZG9101FA-RGBW

I'm trying to properly connect it, but so far I'm having issues such as being unable to detect device in philips hue app and only two color channels are being powered.

This might have to do something with the fact, that I only used single V+ and V- connectors to power device, but device seems to have two of them!

Can anyone explain why does it need to have two V+ and two V- connectors for power input?

Can I use same 12V power source for both of these connectors? If so, can I just split + and - wires in two and then connect?

P. S. I have very little knowledge of electrical wiring, so bear with me.


texts: Minimum wire gauge for 5 Volt, 5 Amp system

texts:
Electrical n00b here. I am trying to create a circuit with 100 ultra bright white/yellow LEDs in parallel (controlled via a rPi)

I figured out that I need an external wall wart, rated at 5V, 5A.

The project require minimum sized wires, I was wondering would telephone wires be "thick" though to handle 5V with 5A?

If not, what would be the recommended gauge of wire to use for this project?


texts: Is it possible to set initial state to a simulink model to do simulations?

texts: Consider that I have built an electrical circuit, or a power system or any other at Simulink and to do simulations, Simulink should work in the sense that it builds a state space model of the system, right? If that is the case, is it possible to set an initial condition of this model? And more, is it possible to know what are the state variables of the model built by Simulink?


texts: Tuning ID-3LA RFID antenna using oscilloscope

texts: I've got an ID-3LA chip wired up to an arduino and an antenna I wound myself with 30 AWG magnet wire.  It works, but I've read that I should be able to tune the antenna by connecting it to an oscilloscope, and then gradually adding or removing turns to improve the signal.  However it's been decades since I've used an oscilloscope and I can't find a good description of where to connect to.  I've managed to connect the probe across the coil and see the 125khz sine wave,  but adding and removing turns doesn't cause any changes, so I think I'm just reading what's coming out of the ID-3LA. Does anyone have experience doing this that can walk me through getting a usable signal to be able to tune this?  Thanks!


texts: Implementing Moores or Mealys State Machine to display different numbers in 4-Digit 7-Segment Display using VHDL

texts:
Ok so i am here again, i posted this question some hours earlier and the answer was to use a state machine in order to achieve it. Now the the question is how do i implement it. I would like it to use these 4 signals : S1 <="0001";, S2 <="0011";, S3 <="0011"; , S4 <="0111"; and display them at the same time. From my understanding i should make 4 std_logic_vector, like that :

     s1           : in std_logic_vector(3 downto 0);
     s2           : in std_logic_vector(3 downto 0);
     s3           : in std_logic_vector(3 downto 0);
     s4           : in std_logic_vector(3 downto 0);

or should i use std_logic_vector(6 downto 0); because i want to input the 7 segment display directly?

The Moore State Machine Code :

use IEEE.STD_LOGIC_1164.ALL;

entity moore_machine is
port (
 clock: in std_logic; --- clock signal
 reset: in std_logic; -- reset input
 sequence_in: in std_logic; -- binary sequence input
 detector_out: out std_logic -- output of the VHDL sequence detector
);
end moore_machine;

architecture Behavioral of moore_machine is
type MOORE_FSM is (Zero, One, OneZero, OneZeroZero, OneZeroZeroOne);
signal current_state, next_state: MOORE_FSM;

begin
-- Sequential memory of the VHDL MOORE FSM Sequence Detector
process(clock,reset)
begin
 if(reset='1') then
  current_state <= Zero;
 elsif(rising_edge(clock)) then
  current_state <= next_state;
 end if;
end process;
-- Next state logic of the VHDL MOORE FSM Sequence Detector
-- Combinational logic
process(current_state,sequence_in)
begin
 case(current_state) is
 when Zero =>
  if(sequence_in='1') then
   -- "1"
   next_state <= One;
  else
   next_state <= Zero;
  end if;
 when One =>
  if(sequence_in='0') then
   -- "10"
   next_state <= OneZero;
  else
   next_state <= One;
  end if;
 when OneZero =>
  if(sequence_in='0') then
   -- "100"
   next_state <= OneZeroZero;
  else
   next_state <= One;
  end if;
 when OneZeroZero =>
  if(sequence_in='1') then
   -- "1001"
   next_state <= OneZeroZeroOne;
  else
   next_state <= Zero;
  end if;
 when OneZeroZeroOne =>
  if(sequence_in='1') then
   next_state <= One;
  else
   next_state <= OneZero;
  end if;
 end case;
end process;
-- Output logic of the VHDL MOORE FSM Sequence Detector
process(current_state)
begin
 case current_state is
 when Zero =>
  detector_out <= '0';
 when One =>
  detector_out <= '0';
 when OneZero =>
  detector_out <= '0';
 when OneZeroZero =>
  detector_out <= '0';
 when OneZeroZeroOne =>
  detector_out <= '1';
 end case;
end process;
end Behavioral;

and the static 7-Segment 4-Digit code :

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;

entity seven_segments is
port(
    clk       : in  std_logic;
    bcd       : in  std_logic_vector(3 downto 0);
    dig_pins  : out  std_logic_vector(3 downto 0);
    segment7  : out std_logic_vector(6 downto 0)
    );
end entity;

architecture Behavioral of seven_segments is

begin

    BCD_process : process (clk)
    begin
        if rising_edge(clk) then
            case  bcd is
            when "0000"=> segment7 <="1000000";  -- '0'
            when "0001"=> segment7 <="1111001";  -- '1'
            when "0010"=> segment7 <="0100100";  -- '2'
            when "0011"=> segment7 <="0110000";  -- '3'
            when "0100"=> segment7 <="0011001";  -- '4'
            when "0101"=> segment7 <="0010010";  -- '5'
            when "0110"=> segment7 <="0000010";  -- '6'
            when "0111"=> segment7 <="1111000";  -- '7'
            when "1000"=> segment7 <="0000000";  -- '8'
            when "1001"=> segment7 <="0010000";  -- '9'

            when others=> segment7 <="1111111";
            end case;
        end if;
    end process;

    DIG_pins_process : process (clk)
    begin
        if rising_edge(clk) then

        end if;
    end process;

end architecture;
```


texts: Chip shorting to ground when connecting the grounds

texts:
I have a pcb that converts USB to RS232, it is using a CH340G and a MAX2323. The output when not connected works as expected.
I try to connect it to a separate device that has its own power supply. When I measure the grounds of connected USB and the device, it reads 70V AC 50Hz.
When I try to connect the grounds, the chips start to heat up as a short circuit.
Any idea why this might happen?


texts:
Hypothetical: I have two circuits that are being powered from the same electrical service. They both have a hot and a neutral wire from the same transformer.

The first circuit and the transformer are earth grounded locally with a ground rod.
The second circuit is earth grounded on the other side of the country with a second ground rod.

Assuming the voltage drop is acceptable for circuit #2:

Are these equivalent circuits?
What problems could occur when a circuit is grounded elsewhere than where its electrical service is grounded?

Hypothetical Schematic

simulate this circuit – Schematic created using CircuitLab


texts: Connector Voltage Ratings Relative/Absolute Across Multiple Pins

texts:
When using connectors with specific working voltage ratings, does this refer to:

The relative voltage between any two adjacent pins,
The absolute voltage relative to anything within the system, or
The voltage across the gap before the connection is made (like with a relay's switching voltage)?

For example, would a connector with a 50V rating be safely usable in this way?

My understanding would be that the voltages only exist relative to each other, so pin 1 at 0V shouldn't care that pin 4 is at 90V, but it equally feels wrong to be using a 90V potential with a "50V" connector.


texts: Fiber-optic transceiver ICs for applications other than fiber-optic Ethernet?

texts:
When we talk about fiber-optic transmission, we almost always talk about copper to fiber-optic Ethernet conversion using fiber-optic transceivers.

But since fiber-optic communication is just transmission of any electrical signal in the form of light, I was wondering if there are other transceivers available for fiber-optic transmission, I mean for interfaces/protocols other than Ethernet.

In my search I could not come across any such transceivers. Whenever and wherever I see the word fiber-optic, it is related to Ethernet/networking only.

Any comments are appreciated.


texts:
I know that there are many LED Drivers out there but most of them are quite big / complex / expensive and don´t do what I need. (all of them do constant-current)

I want to drive a single coloured LED somewhere between 25mA and 100mA (the maximum current is fixed in the application but should be once configurable by some resistor, for example). The LED should shine "as bright as possible" over the range between 0 and 70 °C. So:

I saw the strong current derating of LEDs with temperature, so I could just use the current that is allowed after derating for +70°C over the complete range, but than I might (e.g.) just use 30mA all the time, where at 25°C temperatures, I could e.g. use 80mA and get out more of the LED.

So what I search for is something like a simple temperature controlled current source.

Any suggestions welcome!
have a nice day!


texts: Linear behavior from 0-10V and steady at 3.3V from 10-24V

texts:
Apologies as I have very basic electronics background, and after searching for a whole afternoon I couldn't find out how to implement a circuitry that has this behavior as shown in the graph.

If anyone can point me in a general direction or any available existing reference this would be very much appreciated! E.g. Is there a name for this kind of circuitry, common components used, like transistors or diodes etc. Thanks much!!


texts:
Can someone explain to me how you can power (vcc, vdd whatever) a logic gate in Proteus, with only the input and output pins being shown? Thanks in advance.

The above is the circuit I want to implement. I read that this is the circuit of a basic oscillator.I want to connect the power lines with the power source. Can anyone help me?


texts: MOSFET inverter switching losses/events - 3-phase motor

texts:
To keep this simple, let's focus on one half-bridge which supplies sinusoidal current to the motor. Q1 is the high side MOSFET and Q2 is the low side MOSFET.
SPWM outputs change twice per period - so the current also changes direction twice per period - making these transitions:

Q1 turns off
Q2 turns on
Q2 turns off
Q1 turns on

Let's say the current is flowing into the motor coil. When Q1 turns off, the current is rerouted through Q2's diode. I believe only Q1 experiences switching losses at this point. The same thing when Q1 turns back on. Turning Q2 on and off only reduces conduction losses.
The situation is reversed when the current is reversed - only Q2 then experiences switching losses.
As the current is positive half the time and negative the other, I would say the whole half-bridge has two switching events per SPWM period. Which would mean only one switching event per period per MOSFET.
I've made numerous drawings, wrote some equations, and always came to the same conclusion - one switching event (1/2 turn-on + 1/2 turn-off) per MOSFET per average SPWM period. Unfortunately I can't find anyone to back me up.
Is there anybody that either agrees with me or can tell me why my reasoning is wrong?
EDIT:
I've found a picture and changed Ms to Qs. To be clear - I'm talking about phase currents - the currents through coils L1, L2 and L3. These currents should be sinusoidal, but with a lower frequency than SPWM.

(source: eet.com)
EDIT2:
Seeing there is some confusion about what I'm asking, I'm going to try to explain it further. The picture here is just something I found using google search. It illustrates the inverter (the 6 MOSFETs Q1-Q6) and the 3-phase AC motor (coils L1-L3). MOSFET gates are controled by a SPWM (not pictured here). Please also disregard the colorful arrows. To keep it simple, the SPWM works with a frequency of 10 kHz while the motor rotates with 6000 rpm or 100 Hz (it has just two poles).
Now, SPWM works as they usually do, producing some complicated pattern of the 6 gate signals. Let's say we counted the number of times the Q1 gate voltage changes during one motor rotation (10 ms) and the number is 200. Q1 turns on 100 times and also turns off 100 times in 10 ms.
During that time the current through L1 makes a whole (although noisy) sine wave. So it goes from 0 to \$I_{max}\$ back to 0 and down to \$-I_{max}\$ until finishing back at 0. Half the time the current is in one direction and half the time it's in the other direction.
And finally the question: accounting for the current sign change, how many of the 100 turn-ons imply switching losses?


texts: Took 24V out of a 12V PSU to power a peltier module, the psu died

texts:
I connected a TEC1-12705 to +12V and -12V of a PC PSU (+12v rated 45A, -12v rated 0.5A) then the PSU died. I inspected the PCB and found no burnt traces. What could be damaged?

The IC of the PSU is a JZ6120BD and the -12V rail goes to it. Maybe replacing the IC can bring the psu to working state again? (No caps or resistors were found blown out)enter image description here


texts: What is the contribution of dependent sources while calculating the Thevenin’s Voltage?

texts: I was solving a problem and while calculating the Thevenin’s voltage the dependent voltage source contribution was not taken into account.Why?What important concept am I missing?


texts: Can Hardfault Exception be triggered by hardware?

texts:
I have an Cortex-M7 project that sometimes goes in the Hardfault exception interrupt, sometimes not. With the same code. When it happens it append all the time. My system is made of two board connected together, one has the M7 MCU. When I disconnect the board, the program run fine. When I connect the boards, it goes into HardFault even before initializing the hardware on the second board.

I suspect that the second board change some hardware parameter (Supply voltage, noise, whatever).

Do someone has already noticed that hardware (physical) condition can trigger an Hardfault on ARM cortex-M MCU ?


texts: Circuit Design for Current Measurement at High Voltage

texts:
We're working on a power supply unit for ionic pumps. My supply voltage is 2kV to 3kV with current varying from 0.5mA to 1mA. We wanted to add a high side current measurement indication in these units-an analog voltage (like 5V for 0.5mA). First part of the circuit is sensing the current and in our research we came across the ACS product line, particularly speaking of ACS722KMATR-10AB datasheet attached here it offers Isolation for 4800 Vrms. For amplification we were thinking of using ADA4528, MAX4238 and AD8428. We want to know a few things:

A. Is the term Isolation Voltage in any way related to the Voltage Rating of the sense resistor of ACS722KMA? If not then what is the Voltage Rating of the sense resistor?

B. The Basic Isolation Working Voltage for ACS722KMA is stated 1097 Vrms in the datasheet, there is a little confusion if ACS722KMA be able to survive constant 2kVDC to 3kVDC ?

C. I came across another article, The schematic attached in this EEVBlog suggests another simpler method of measurement but unfortunately I wasn't able to find current sense resistors with High Voltage Rating.

How can I measure 1mA from a 2kV source?


texts:
Does anyone have any experience in using the Enhanced Parallel Master Port on the PIC24 family?

I am trying to use the example on page 42 of the EPMP manual - the "Read Example".

My problem is that the example doesn't even begin to even think about the vaguest possibility of working.  The very first bit:

#define EXTERNAL_RESOURCE_SIZE  0x20000L
#define CS_START_ADDRESS        0x200000L

// define an array in EPMP EDS space to access the external resource
__eds__ char pmp_data[EXTERNAL_RESOURCE_SIZE]
    __attribute__((space(eds), address(CS_START_ADDRESS), noload));

will not compile.  It complains:

error: size of array ‘pmp_data’ is too large

Now, the EPMP on this chip has 23 address lines.  That's a massive 8MB of address space - coupled with 2 CS lines, so a total possible of 16MB.  This is only 256KB I am using (the example in the manual is for 2 x 128KB memory chips, which is as it happens just what I have here).

So what's the game here?  I have had a poke around in the linker scripts, but nowhere in any of the chips' scripts can I see any mention of the EDS space.  I am, quite frankly, lost in those gld files, and last time I tried tinkering with one it broke it completely.


texts:
I will be designing a circuit for 8 stepper motors. these stepper motors require 12V and atleast 3A. at most only 2 stepper motors will move at the same time.

Will a 12V 30A bus be enough or advisable to control this? how can i also design this to be safe and error-less


texts:
I'm interesting of how can graphics cards detecting what type of TV has connected with S-Video? TVs sent some indefiniter signal back to the computer? And how it's working (protocols, signals, freq, etc)?
Thanks.


texts: What is the reference for High side IC with internal mosfet driver

texts:
In the schematic below (like many other) the IC (switcher) is on the high side.
I was really curious how the internal circuitry of such an IC is referenced to.

My first thought was that everything is referenced to the source. Because my reasoning was that internally there is a N-channel MOSFET, so you would want to drive referenced to the source.
What contradicts this reasoning is that the source is a switching node.

But if they use the drain as reference, then how do they sense and drive etc

My question is not specific for this IC, but in general for high side switchers.


texts: Power rating for opto-triac trigger circuit resistors

texts:
RHS will be using 220v 400watt bulb

2 simple questions
1- does the 360ohm resistors has to be of high watt too ?
2- all i can find is 5-10watt resistors, can i use them ? would they snub correctly ? (will use 3 in series to get the ohm i need) what do i do ?


texts:
I am looking for .gitignore file for the Lattice Diamond IDE.  I've been trying to only add what I need, but it would be nice to have a .gitignore that just ignores all of the automatically generated files for build/documentation/etc.  Yes, I could sit down and make one myself, but a ready-made already existing file would be ideal.

The build process that Diamond runs through, plus any IP thats included from their included tools, all generate a lot of files, some necessary, many not.  I've not come across a clear definition of what is needed and what is not, nor have I been able to find a boilerplate .gitignore for the IDE.

I debated where to place this question, I apologize if it is off topic here, however electronics SE seemed like a best fit since it involves an FPGA IDE.

EDIT:  I would really like an explanation as to why this is being downvoted.  If anyone has resources I am missing about what files Diamond generates that are temporary, then by all means please downvote.  But I would also appreciate a point in the right direction.  I spent a good while searching through Diamond documentation, and would love to be proven as an idiot, so long as it means I get a good answer.


texts: Heat dissipation in stepper motor running for long time

texts:
Background

I want to run a 28BYJ-48 motor for 8 hours a day over a week. I am concerned about the motor overheating throughout the day.

What I know

The motor draws 92mA of current and takes 5V, generating approx. 0.5 W of power. I know that power is converted to motion and heat (and that motion is proportional to current, and heat is proportional to current squared).

Question

In what proportion is that 0.5 W of power transformed into motion and heat? If this is dependent on some spec of the motor, what spec should I be looking at?


texts:
I have a set of xmas LED lights (400)
After a short use the lights developed a fault, about the first100 lights are on then 100 off then 100 on then the last100 off there are also a few here and there that are off.
On checking the wires 2 wires come from the controller , one goes to the first LED which then divides into 2 then each LED has 2 in 2 out all up the string.
The other wire flows the full length and joins the end.
What could be wrong and how do I fix


texts: Can you setup UART Reception on dsPIC33EP512MU814 on eval board dsPICDEM MCLV-2

texts:
According to microchip, the dsPIC33EP512MU814 can be integrated with the dsPICDEM MCLV-2 Development Board using dsPIC33EP512MU814 Plug-In-Module

However, according to the dsPICDEM MCLV-2 Interface map the UART Rx and Tx of the evaluation board are pins 49 and 50, respectively. So then according to plug-in-module interface map that UART Rx must be mapped to pin SDA2/RP100/RF4, and UART Tx must be mapped to SCL2/RP101/RF5.

I'm aware that you can map out UART Tx to RP101 by simply assigning

RPOR9BITS.RP101R = 1;

However I was expecting the pin of UART Rx to be RPIx not an RPx.

Does this mean you can't perform UART Reception?


texts: Why do musical tesla coils sound more like square waves?

texts: When people modulate their tesla coils to play music, it sounds like a very sharp square wave, as opposed to the electrical signal, a (roughly) sine wave. Why doesn't the tesla coil sound like a sine wave, which would match the electrical signal?


texts: Can a voltage source be DC and generate a sawtooth signal?

texts:
Pretty much what the title says. I'm fairly confused with this simple question. Shouldn't waveforms which change amplitude be AC?

EDIT: So this is about a RAMP Type DVM (Digital Voltmeter). Can the input signal be both DC and sawtooth is my question?


texts:
I'm working on a low-low power system, which is powered by a little solar panel and a Li-Po (Lithium-ion Polymer) battery, which can be \$20\$ or \$ 50\:\mathrm{ mAh}\$. The capacity by now is not important, since it's only a buffer to store the energy given by the panel, that should guarantee autonomy.

Today we were discussing the fact that Li-Po batteries have a leakage, that somewhere (I don't know the source) is indicated to be the 20% of the capacity in one month. So at first glance, seems that the smallest battery, as long as it can store the necessary energy to survive when there is no light.

But I'd like to measure how much is this leakage; the idea was to feed the battery with a small current (around \$ 1\:\mathrm{ \mu A}\$) and check if the battery voltage increases or decreases over a long time. But I'm not very aware of the chemical processes happening inside, and I think that this technique may involve other factors. So there is a better way than charging the battery and waiting to see it discharge?

Update

For reference, the battery we're currently using are Fullriver toy series 301213HS10C and 501417HS10C (same page). As can you seen, the manufacturer doesn't give these (and many other) specifications, so I want to measure it by myself.

The battery is charged by a LTC4071 shunt battery charger which has a really small (550 nA) operating current and which we have measured having less than 10 nA of leakage when the battery voltage is higher than the panel one.

And for me  \$20 \:\mathrm{ \mu A} \$ are critical, since the panel in the worst case we consider (about \$50-100 \:\mathrm{Lx}\$, wich is in a room with no direct light on the panel) deliver \$10-20 \:\mathrm{ \mu A }\$, and the module consumes about \$10 \:\mathrm{\mu A} \$, taking the duty cycle into account.


texts: Verilog Netlist and verilog file not justifying each other

texts:
i generated a verilog netlist file with the help of a test case for 2-1 encoder .To test the netlist i draw the schematic diagram and try to find the output.I can't upload the pic of schematic which i draw by hand but below is the verilog file

module test (input [1:0] in, input enable, output reg  out);

always @(in or enable)
    if(!enable)
        out = 4'b0000;
    else begin
       case (in)
           2'b00 : out = 0 ;
           2'b01 : out = 1;
           2'b10 : out = 0;
           2'b11 : out = 1;
        endcase
    end
endmodule

which says that output must be 0,1,0,1

i generated a netlist which is given below

module test(enable, in, out);
input [1:0] in;
input enable;
output out;

wire  synth_net_4;
wire  synth_net_9;
wire  synth_net_12;
wire  synth_net_17;

wire  synth_net_19;
wire  synth_net;
GND synth_GND_0(.out(synth_net_4));
GND
    synth_GND_1(.out(synth_net_12));
MUX4 synth_MUX(.in({synth_net_17,
    synth_net_12, synth_net_9, synth_net_4}), .select({in[1], in[0]}), .out(
    synth_net_19));
VCC synth_VCC_2(.out(synth_net_9));
VCC synth_VCC_5(.out(
    synth_net_17));
BUF synth_BUF(.in(enable), .out(synth_net));
AND2 synth_AND(
    .in({synth_net_19, synth_net}), .out(out));
endmodule

but schematic with respect to this netlist give output as 1,0,1,0.So am i doing something wrong in getting exact schematic?I just want to validate that netlist corresponds exactly to verilog file.


texts: Calculating the resistance for the base of a transistor

texts:
I'm building a circuit for my little niece's birthday (I'm already overdue with a couple of days).
I started building it before I well understood enough about transistors and no I'm running a little out of time.

The whole project (it's actually a small city, build with recycled parts, in which I placed a lot of LEDS) is nearly finished, what's left are putting the resistors R10 - R19 in place.
If somebody could take a look at the picture and tell me how I should calculate the value of these resistors ?

Also, Can I power the arduino (5v) with the same power source (12v) using only resistors, or should I use a step down convertor (or build one) ?

I think I'm going to choose this adapter instead of the one I was previously talking about. It was previously used for a USB Hard disk and supplies both 12v and 5v. It probably has a regulator built-in ?
How do I know ?


texts: Why is the stored value in each D flip flop reconnected to the input in a buffer register?

texts: Like can one not just connect a single AND gate with the load and X input instead of complicating by reconnecting the output and using another OR gate? Will it be logically the same? or is it that I am missing out on something?


texts:
Lets assume we have a wire passing a magnetic field, it is know that EMF is induced due to the magnetic field, what if the wire is not connected to a circuit what happens?

Is there ay voltage in the wire? I doubt there, is.. and current can not flow in an open circuit so what will happen?


texts: On a transmission line, why does max power transfer occur at impedance matching?

texts:
I do not intuitively understand why max power is transferred when the characteristic impedance of a transmission line is equivalent to the impedance of a load.

A voltage wave going through the transmission line is already traveling through a certain impedance. When it encounters the load, the load's impedance is exactly the same, so the voltage wave should pass through it in the same way it has been passing through the previous part of the transmission line. The load should act as just another part of the transmission line because there are no differences between the impedance.

--edit--

Many answers aren't addressing my question about why the wave would be absorbed by the load rather than pass right through it.


texts: Circuit to exaggerate differences in current

texts:
Basically what I am after is some sort of a circuit which will amplify higher voltage signals, but possibly dampen lower voltage signals, in order to make a wider separation between high and low voltage. This is just for a little DIY project I am working on at home, and basically it would be comparable to setting your audio equipment to "Theater" mode vs. "Quiet" mode.
Would this be easily accomplished with a fairly simple circuit, or am I trying to go after something far too complex for a beginner?

What would be the name of a circuit similar to what I am attempting to build?


texts:
I have seen many videos about earthing but I couldn't understanding why the current would flow from live to ground (earth) if one touched a live wire.
Suppose I am in a house and I touch a live wire while standing barefoot on a concrete floor.

Would I be electrocuted?
Isn't the concrete supposed to be non conductive?
Even if the current flowed to ground, isn't there no connection between earth and live wire? Why would the current go to ground?

Also I have another question out of curiosity. The mains tester we use in our home in which we put our finger on the cap and the bulb glows. Is it based on the parasitic capacitance of our body?


texts: Whats the difference between time changing electromagnetic field and electromagnetic waves?

texts: When a charge is accelerated its said that it produces electromagnetic waves. They also say that an accelerating charges produces time changing electromagnetic field and which when passes through a conductor induces voltage in it. I wonder are these two terms same ? Electromagnetic waves is the concept used in communication while electromagnetic field/induction is the concept mostly used in motors,transformers and generators. Please explain. I am confused on it.


texts:
I have a project with many buttons and leds. I currently have 2 daisy chains for buttons and each chain has three shift registers (74HC165). I do the same for my leds (STP16CP05) But even with with three chains.

Would it make a speed or led brightness difference, if I connect all shift registers to one chain (one for leds and one for buttons)?

I somewhere read that the more shift registers I chain in a chain, the slower it get's to read/write the values. Is this true?


texts:
I am reading a datasheet on the 28F010 flash.
The datasheet states that for reading it behaves like a ordinary EEPROM but in order to alter memory content the command first the command must be issued.
So then in datasheet there is a diagram where 28F010 is connected to a 80C186 processor.
My question is how CPU will be able to write this flash memory?
When we access the address for writing the CPU will generate standard signals on it't bus. CPU will not generate any command for writing because he doesn't know about the flash.
So i guess if 28F010 is connected to 80C186 the CPU will be able to read this flash only.
Am i correct?


texts: Computing the input voltage that turns the LED on

texts: We assume that the LED will light as soon as the transistor comes out of the cut-oﬀ region, therefore the BJT is on and operates in the active region. I know that that Vbe = 0.7V, Ib>0, ic=BIb and Vce>=0.7. Is this inequality for Vi expected for the BJT in the active region? If so, what value should we expect fot saturation mode?


texts: Why do LEDs have only RGB (Red, Green, Blue) colors why not others?

texts:
After some studies I've found LEDs having 3 colors RGB (Red, Green and Blue), I was very interested in this topic so this question is up. The Diagram will tell the colors in LEDs.

> Red, Green and Blue color in LEDs

  Why only RGB is needed?

  Why can't any other color be replaced?

  Why MCY Cannot be used?


texts: What is the purpose of this spiral wire on top of the transformer body?

texts:
A follow-up to What are the ratings of vintage Selenium Rectifier B20/16-2,4?

The photograph linked shows, in the red-box, a spiral wire on the transformer body.
What is the purpose of this?

p.s. I vaguely recall a similar (pardon my language!) contraption on top of a sub-station transformer - think it may have been at a Railway yard.


texts: How to calculate RMS of total noise from digital Oscilloscope (FFT)?

texts:
Only the red channel is in consideration. The yellow curve is not relevant, which is only another channel of the oscilloscope.

The image above was captured from a digital oscilloscope. The vertical axis is in dBu, which can be converted in to Volts. And the horizontal axis is in kHz frequency, with a frequency resolution of 1.2Hz.

Assuming all the data of frequency vs voltage at every single frequency could be obtained, Could I ask:

How to calculate the RMS value of the noises with bandwidth from 0Hz
to 3.6Hz(only three points)?
how to calculate the RMS value of the noises with bandwidth from say DC to 10kHz?

EDIT

One answer mentioned that the more points exist in a given bandwidth, the lower the voltage level will be. However this is not the case according to experiments.

The signal source is not connected with anything, which means leaving the oscilloscope unconnected.

Picture 1 shows acquisition time of 8.192s, indicating a frequency resolution of 0.12Hz.
Picture 2 shows acquisition time of 26us, indicating a frequency resolution of 38kHz. However the noise floors for these two diagrams are the same at -105dBu.

EDIT 2
2015-03-21

For the above two diagrams, the noises floor are similar. It is because for the above two cases, the noises come from quantization noise of the ADC of the scope.

The TOTAL noise power of the quantization noises are always the same between 0 - 0.5*fs(from zero to half of the sampling frequency), no matter what the fs is.


texts: I have heard some people talk a bit about negative resistance, but I have never really understood it. What is negative resistance?


texts: Convert a Ngspice rawfile to binary format

texts:
I have these NgSpice rawfiles that are generated in ASCII format instead of binary format.
I would like to know please what command to use to force their generation in binary instead or ASCII format when running the NgSpice simulation in batch mode? If no such thing exists it there a command that converts ASCII files to binary ones?
Thanks in advance


texts: How to keep voltage when using two diodes to run two irrigation stations?

texts:
My limited knowledge of electronics allowed me to solve a 'problem' that I had with my sprinkler controller.

I wanted to run zones individually, but for some zones also wanted to run them together (in order to essentially have lower water pressure and throw the water to a different locations than what it would at full pressure).

So on the wiring to the controller I would, for example, wire the solenoid of one zone to the controller's zone1, and wire the solenoid of another zone to the controller's zone2 (There's a common wire that is also wired to the controller for all solenoids to complete a circuit). Then I would use two diodes to go from the zone1 wiring to zone3 on the controller, and from the zone2 to zone3.

Yay, it worked.

However, I noticed the solenoids were 'clicking' on any combined runs. I'm guessing this is due to a voltage drop? Is there a way for me to get the correct voltage to each solenoid?

Thanks

EDIT:
Here's a picture of what I did, very convulated to look at but, all I am doing is adding the diodes in at the controller, clearly I have no ide what I did :) I thought of the diode as a one way street, so when (in my example) zone3 is triggered the completed circuit (via the common wire - white) between zone1 and zone2, whereas when zone1 was triggered it would not go through the diode through zone3 and to zone2.

So the green wire(zone6) and yellow wire(zone5) go to zone3, so if I trigger zone3 they both go.

ADDED 2:

I think I almost have it, but I feel like my problem is that I have this white common wire coming back from all the solenoid valves, which I can't isolate. In the first diagram I can get what I want (but that isolates every second wire to each solenoid, which I can't do without digging up the yard). On the other diagram with the second wire common, I get undesired current flowing half the time to the unintended valve.

Am I missing something obvious, or is there no way around having the second wires isolated?


texts: Connecting capacitors in series after charging them

texts:
Assume I have two identical capacitors and charged both equally. If I measure C1 with a voltmeter, I read 5V, and C2 reads 5V. If I connect the positive leg of C1 to the negative leg of C2 (connect in series) what would the voltage be across the series capacitors?
Googling series capacitor seems to suggest they add up to 10 volts but I am highly doubtful and somewhat scared to try.
Wouldn't all the holes of the positive C1 leg rush to merge with electrons in the negative C2 leg and quickly deplete the charge, possibility resulting in an explosion if the capacitors are big enough?


texts:
I would like to build an oscillator that will satisfy a few requirements. The main requirement is to have exactly one capacitor. Another one is to have high Q and sine wave output.

I am considering Hartley's oscillator design. Since it has only one cap. I don't what to built the biasing network and select a transistor that will suit the oscillator's needs, so I figured that there must be a way to build Hartley's oscillator around an operational amplifier as shown on the figure below.

I have made the simulation as shown above, and I believe it should oscillate, since the gain of the Op Amp negative feedback loop is greater than \$\frac{L1}{L2}\$ ratio. But the oscillations start and die. I can see that the frequency of the decaying oscillations is correct, but they would not sustain. I event tried to crack the gain up to some unreasonable number, but this doesn't help at all.

Can anyone advise me as to what I'm overlooking and how to make this circuit oscillate?

PS. The simulation uses 741. If is is not the best op-amp for the job, then what would be a good replacement?


texts:
I'm trying to use a MAX485 module to interface a RS-485 domotic bus, when I use the oscilloscope I see that the original bus signals (A and B) are between 1.9 V high and -2.250 V low (4.15 V amplitude, total differential between A and B of 7.3 V):

When using the MAX485 module with an Arduino Uno, I can't seem to get those kind of output voltages. I've tried connecting the module's VCC and DE/RE with several different voltages (3.3 V up to 11.7 V) but I can never get a diferential as high as the BUS i'm trying to interface:

On the spec sheet (data sheet link) it says "Driver Output Voltage (A, B) -8 V to +12.5 V", but there seems to be no big difference on the output voltages using either 5V or 11.7V VCC, so how do I control the output voltage?


texts: Xbee-Arduino serial input (outliers problem)

texts:
I have an Xbee configured as receiver and Arduino (standalone w/ atmega328p chip) connected together. The RSSI pin of the Xbee is connected to one of the Arduino Board PWM pin. I used the PulseIn to get the digital equivalent of the RSSI (i named it rssiDur) I used the Hyperterminal to display the rssiDur value. The rssiDur values displayed on the HT is not consistent. Any interference between my Xbees changes the rssiDur dramatically. I wish to stabilize the rssiDur reading so that the interference will not be of great effect.

it has been suggested to use a timer. i don't know how though. it was something like when the rssiDur displays 10 consecutive of the same value, that value will be the rssiDur. ( example: 9 9 9 9 9 9 9 9 9 9 8 8 6 7 10, rssiDur=9) Does anyone know how to do this? Or any suggestions on how to treat the values of rssiDur? it will much help on our project.

**Update: Hi again! I used the Average Library but I am still getting outliers every now and then for example: (copied from HT)
:
  25
4
25
27
25
20
32
1
24
24
20
20
27
28
20
22
20
19
1
3
19
18
20
20
1
20

how do you throw out the outliers? Will it be advisable if I used a double Mode filter?


texts:
Suppose I connect the two terminals of a battery without any resistor resulting in a short circuit. Doesn't that mean the voltage is zero across the terminals of the battery? From Ohm's law V = IR and when R =0, V = 0.

But how is the voltage zero when one terminal of the battery is clearly at a higher potential? The positive charge is concentrated at one terminal and the negative in the other. So how come the voltage becomes zero in a short circuit?

I also can't wrap my head around the fact that voltage immediately becomes nonzero when you add a resistor. I know it works according to Ohm's law. But I don't just get an intuitive idea.


texts: Help by identifying a smd FET in Philips Hue power supply

texts:
One of our Philips Hue lamps died recently and I found that the power supply is the reason.
Two resistors burned (most likely due overvoltage from the mains).
However there a SOT-23 packaged component that I couldn't identify.
Probably this is a http://www.alfa-mos.com/datasheet/HVMOS/AFN501DEA.pdf, but I'm not sure. Check the photo below, "501de".
Unfortunately, I didn't find an alternative/replacement component for this. Could somebody help to find one?
Thanks!


texts:
There are tons of electrical descriptions of I2S; however, I cannot find information about how the data is formatted/structured. What I mean by format is, what does a value on the serial data line mean? Do these values have information on volume, pitch, or something else?

As an application example, I have a .wav audio file. I unpacked the file and obtained a stream of data samples. How should this sample data be transmitted on I2S so that a receiver can play the audio? 0x 0011 2233 4455 6677 8899 AABB CCDD EEFF 0011 2233 4455 ... and so on. Should these values be formatted in some way that is meaningful to the receiver? Maybe something like 0x0011____, 0x2233____, where blank means other miscellaneous information?

Let's assume for the case of I2S Standard, 24 bits per sample. Any information would be helpful. Thanks.


texts:
I'm working with the Teensy++ 2.0 dev. board. It uses the AT90USB1286 8 bit AVR 16 MHz microcontroller. I'm using the microcontroller to drive a small solid state relay.

This was just a basic simulation that I ran. I am actually using a TLP222A relay instead of the MOC205. The 5V from the microcontroller, across the 390 ohm resistor (factoring the forward voltage of the diode) will give me ~12 mA of forward current. I have tested this circuit with a bench power supply as my "microcontroller" to supply 5V, and it worked great.

On my Teensy++ board, I am able to measure 5V at the pin with no load. But as soon as I connect it in the circuit, my voltage output is only about 1V.

void initialize (void) {
DDRB=0b11111111;
}

int main(void)
{
// set for 16 MHz clock, and make sure the LED is off
CPU_PRESCALE(0);
LED_CONFIG;
LED_OFF;

usb_init();

while(1) {
    PORTB = 0b11111111;
    LED_ON;
    _delay_ms(3000);
    PORTB = 0b00000000;
    LED_OFF;
    _delay_ms(3000);
}
}

Above is a bit of my code. The main piece is that I set DDRB to outputs and then in my while loop I toggle the output on and off.

I trust that there is no issue with the resistor or relay, since they work properly when I use a bench power supply in place of the microcontroller. I have tested multiple pins/ports from the board.

Thank you for the help! It's much appreciated!


texts: Timing control within a loop - Sending data at exact intervals

texts:
We have a program where we are sending data wirelessly through GPRS. We retrieve values from ADCs, do our calculations, display it on the screen and also send it to remote servers. The loop can be though of as this

while(1)
{
  _ReadADC();
  _LCD_Display();
  _DoCurrentCalcultions();
  _SendCurrentData();  /* I want to send this data exactly every minutes */
}

The problem that I am facing right now is occasionally data is not send successfully so there are skipping, but that is not what I am concerned about.

I want to be able to send data exactly every time, e.g.
11:00:00, 11:01:00, 11:02:00  note that the second value remains same only minute value changes. Now I do not have Real Time Clock (RTC) on my board but definitely have timers. What I am thinking is that I should give some slack time in my loop and if the calculations take more or less time, I should adjust that time in the slack and send data precisely every minute.

How can I do that, it has been long since I did embedded systems programming.


texts:
Recently I switched from the leaf-spring type of DIP sockets to the more expensive machined MIL sockets. The leaf-spring type were failing (by the spring parts pulling out of the socket) after a few insertions, or maybe just over time), but the MIL types don't seem to hold the part securely. Notice how this one relaxes into a cockeyed position after having been pressed firmly into the socket:

Are the MIL sockets supposed to be used with some kind of a hold-down?
Did I get an atypically bad batch of leaf-spring types, and is there a brand or supplier whose sockets can be counted on?

Update: Isn't the point of socketting to permit removal for replacement or, more frequently, for reprogramming (and if not, then why socket instead soldering the chip directly)? ZIF is a tool for the lab or assembly house, not a part to go on a product. It's bulky, heavy and expensive. Is there no kind of socket that's any better than having to unsolder a part?


texts: Extending the wires of soil moisture sensor without voltage drop

texts:
How can I extend the wires of my soil moisture sensor without dropping analog output voltage?

My control box is 15 meters from the plants. I also have my 5v power supply for my sensor. I have 2 sensors.

Specification for control box:

Power supply: 3.3v or 5v
Output voltage signal: 0~4.2v Current: 35mA

Pin definition:
Analog output (Blue wire)
GND (Black wire)
Power (Red wire)


texts: huge reverse current leakage in fast recovery diode for boost converter

texts:
i have a boost converter circuit that will boost 12V to around 180V, the circuit is works pretty good but there is huge reverse current in fast recovery diode right before the load, here my circuit and the simulation

the green line is voltage in R3 (ignore the value cos i know how to control that), the blue line is the current through D1, as you can see, in the very beginning, the current has opposite direction which is i assume as reverse current in D1, the question is

how can the current go reverse the diode? it must be blocked right? since the maximum blocked voltage around 1kV
if it is how supposed to be, can i assume it as surge current of diode?

thank you


texts: Sniffing USB traffic at the hardware level

texts:
I've been looking to purchase a USB sniffer that will parse packets at the hardware level. I've used usbsnoopy and the like, but a filter driver solution is not my goal here.

Does anyone know of a hardware solution for this? Thanks.


texts:
I understand the problems with parallel LEDs sharing a current source. However, I came acrosse this LED from Cree, which, in one configuration described in the datasheet, has its internal LEDs electrically in parallel:

It seems like Cree knows what they're doing with LEDs, so there must be some reason this works. I am imagining some sort of extremely tight binning scheme for the individual chips before being put into the modules, and I supposed they're pretty well coupled thermally inside the package. My understanding is that they would have to bin not only based on forward voltage but also based on temperature coefficients, which seems infeasible(?)

If you look very carefully you will see the electrical connection putting the two strings of LEDs in parallel are outside the package, and they describe an alternate configuration where the strings are put in series. I also can imagine another setup where each string gets its own constant-current driver (or really beefy resistor), but that adds a lot of cost and complexity.

My question is, will using a Cree XLamp MHD-E series LED in a 9-V configuration degrade the performance or lifespan of the LED, and if not, how is this possible?


texts: A poor man's alternative to a network analyzer for antenna matching

texts:
I'm doing a small board with a 915 MHz transceiver. A small helical antenna is used, which is located on board with a very short path (10 mm) from the IC, including balun and a matching network. There are no RF connectors or real state available to include any. Since I'm constrained with the board space and the board needs a plastic case, I couldn't follow the manufacturer's guidelines for them so I need to at least do some antenna matching to ensure maximum transfer. The problem is that I don't have access to a network analyzer, so I'd like to know if there is some manual method I could use, besides randomly trying L and C values and measure the output. I don't need serious antenna performance, but some reasonably "good" one (a relative term, I know).

The board has footprints for two 0402 components, one series and one parallel. IC's crude power output is around 20 dBm. From the IC's development kit I've got boards that have a good antenna and good matching for it (other kind of antenna). I was thinking I could do some continous transmission from my board and get a relative power measurement from the dev kit receiver's perceived RSSI. I could compare the results with measures obtained from another dev kit board in countinuous transmission. Then I would perform some brute force by trying out L and C values. I could also choose from 10 different channels in the 915 MHz band (902~928) and see what diference I get. I know that's terrible, but hey, that's why it's called brute force.

Is there a better method? Is there any cheap (<$100) equipment I could use to get some measurements? Please mind that I live in an underdeveloped country so "buy some xxx on eBay" is not within my possibilities.

Any suggestions would be greatly appreciated.


texts: Meaning of strong and weak drive in VHDL?

texts: What is the meaning and effect of "strong" and "weak" drive shown by (0,1) and (L,H) in VHDL's package  ieee.std_logic_1164?


texts: Does this buffer's current rating apply to each individual output, or all of them?

texts: I'm thinking of using a SN74ABT244A octal buffer in a circuit that requires the buffer to sink 20mA of current on all eight outputs under worst-case input conditions. In the datasheet, it says that IOH is -32mA, which should be enough. However, I am confused as to whether or not this applies to each individual output, or all outputs on the entire chip, in which case I would be sinking 160mA of current and severely exceeding the current rating of this chip.


texts:
So I bought a new Christmas tree this year.  One with LEDs which makes setting up and tearing down simple.  It has a remote control which can set the lights blinking in different patterns.  A lot of really brilliant reds, blues, greens, violet, orange, and white.  They can dance and repeat patterns, chase each other up and down the tree, all that.  It's really pretty great.

Then I noticed something puzzling.  The replacement pack of lights.  For the tree they gave me a small packet of 6 replacement LEDs.  Enclosed is a picture of one.

My question.  How in the world would this work?  It's a two wire connection.  From the variety of colors there has to be at least 4 LEDs in there - RGB and W.  How can the CPU in the base of the tree address any light in the thread and assign it a color with only two wires?  Anyone know the protocol this thing is using?  How can they get such color diversity and positional addressability from only 2 wires?


texts: How to increase watts going to my lithium battery?

texts:
I have a 48V 50Ah 2000W lithium battery for my ebike, I am currently using a 12V 160W solar panel with a GVB charge controller with MPPT and getting my battery to charge but only getting 350W, how can I get a full 2000W?

MPPT datasheet can be found here.

48V 50Ah Li-ion Battery pack is made of 16 pcs of 50000 mAh Li-ion Cells
One Special 14 cells PCB with balance function is installed with battery pack to protect battery from over charging, over discharging and over drain

Voltage: 48V (Rated voltage:51.2v)
Capacity: 50Ah
Cut-off voltage: 35V
Max. discharging current: 100Amp
Max Continuous Discharging Amperage: 50 Amps
Rated Discharging Amperage: 50 Amps
Charging Current: <10 Amps
Charging Voltage: 58.8 Volts