texts:
I'm working on designing an 8 bit home brewed CPU and in this process I'm using Octal D Flip Flops as registers to store data.  One of the issues that I've ran into is the need to execute multiple functions in a single main clock cycle.

In order to do this, I'm fetching data from memory, placing it on the data bus, then clocking it into a register all in a single operation.  I'm worried that the rising edge of the main clock will happen at the register before the data is fetched from memory.... a sort of propagation delay / race condition.

The only way I though to counter act this is to AND the flip flop's clock input with a clock that is faster than the main clock... that way data will be guaranteed to be clocked in at the end of that cycle.  This does bring up a problem with data being clocked in over and over again, but I'm not sure if this is an issue.  Any recommendations?  Do I need to provide schematics?

EDIT:

Here's a small schematic for a register.  I have three buses in the picture: data, control, and state.  Depending on the OP code on the control bus, and the state, the flip flop will be clocked in.  Note that I am ANDing with MC which is a clock that I set up running twice as fast as the universal clock.  This is described above.


texts: Floating Point: What do "Bits Precision" and "Decimal Precision" Mean and How To Convert Between Them?

texts:
I've seen the following table on Wikipedia:

However I couldn't find an explanation regarding what "bits precision" and "number of decimal digits" are and how they are related. What do they mean exactly? How to convert between them?

Thanks


texts: Sometimes I get unmotivated to finish my personal projects because of a lack of plan on what to do next--should I design a board first, hook up a test circuit, write test code or write design requirements?  Are there any formal design flows maybe specific to embedded hardware that I could follow to make sure I don't miss anything and waste time re-doing things.


texts:
I have an I2C slave device in which the maximum input voltage to SCL & SDA is 3.6V.
And the I2C Master device is PIC16F877A operating at 20MHz which provides a 5V output on SCL & SDA.

Pls help me to interface these two devices.


texts:
I'm trying to make an 8-bit Display using 4 seven segment displays being driven by a single EEPROM (like in this video).  From the video, I used the design of the 555 timer and a dual JK flip-flop to count 0 to 3.  The clock works, however, when I wire the flip-flop in the same way as is done in the video (Both presets, clears, Js and Ks high and connect the clock to the clock1 pin and the clock2 to the output of the first flip-flop)

The two LEDs do not count up in binary as they do in the video instead, they both stay on.

I noticed that there are a few differences between the datasheets of the flip-flop I bought (CD4027BE) and the flip-flop he has.

On his datasheet, he has two preset pins and two clear pins whereas
I have two set pins and two reset pins (although I do not think this
is anything major)
On his datasheet, he has a toggle feature in the feature table where
    as in the datasheet I have, there is not a feature table.

So my question is have I bought the wrong flip-flop or am I wiring it incorrectly and if I have bought the wrong flip-flop can I make it work with this flip flop?

Additionally, the desired output is:

0,0 - 0,1 - 1,0 - 1,1 and repeat.


texts: Capacitor replacement on ancient Fisher & Pykel fridge - which pins to connect?

texts:
I have three pins on this compressor:
[a] white wire post - live phase - bottom left
[b] capacitor resister - copper terminal - top left
[c[ black wire post - ground to wall - bottom right

It's so old it's probably one of the first ever made: ABE021 is the serial.

When completely cool - meaning the compressor is unplugged and not running, cold to the touch - the fridge will start first time nicely, and run well for 10 minutes.

I reckon the start capacitor is blown, and when the thermo-resister (shown as capsule shaped copper in pics) is preventing the cap or start coil from getting enough juice for a 2nd re-start. Instead I can hear the relay clicking back in place due to lack of rotation energy, but i can hear the compressor spin still.

I plan to connect a new capacitor to one of the three options, with impedances:
a/b - 70 ohms (relay???)
a/c - 27 ohms (run coil?)
b/c - 42 ohms (from capacitor to ground) <---- current choice to add new cap.

Model ZS4/14 and E00 BBA 023
Model KS400 and very early serial: E00 ABE 020

I would say if there was someone there called ABE, then this serial is even earlier than might first seem!


texts: Have Pins light up after pushing a button/switch

texts:
I'm trying to create a "Push Pin" map for a friend as a gift. My friend has traveled through out the world and I'd like to organize the pins by year. So a different color pin for each year he has traveled to a specific location. I'd like to take it a step further and have the different "year pins" light up. For example, I'd like to be able to push a certain button or switch and have all the 2008 pins light up, push another button and all of 2009 pins light up, push another button and all of the pins light up. Does anyone have any direction they think would be a good place to start?

Thanks!


texts: Using earthed appliances and extension lead with unearthed (Sweden) socket

texts:
I live in an old building in Sweden and the sockets are unearthed. Two pronged EU type.
I want to plug in an extension lead (earthed) and to have 3-4 appliances running off the extension lead. The appliances would be 1) lamp, 2) phone charger 3) TV
Would this be ok/safe to use earthed extension lead and appliances through an unearthed socket? What are the risks? I don't want to frazzle the TV or myself!
Also in Sweden they sell earthed and unearthed extension leads, which would be most suitable in this instance?
Thanks very much for any help/answers!
EDIT:
Thanks very much for all useful and helpful answers! Much appreciated, really overwhelmed actually by the time taken to provide such comprehensive responses, testament to great community knowledge and helpfulness so thanks again. I will now only used double insulated devices in the unearthed socket and until I have an electrician swap it out to an earthed. Cheers!


texts:
I have a LiFePO4 battery connected in 2P4S configuration. What happen if one of the batteries is short-circuited? The other batteries will also be short circuits, or this will be result in the venting of one battery?

update:

Thank you for the answer, but the batteries are connected in this way:

What happen to the other cells conneceted in series (BAT6, BAT7, BAT8) if we have an internal short circuit of the BAT5 ?


texts:
I have the following logic circuit:

And I'm asked to identify the minterms in F's truth table.

The expression for F is

F = C + A'B'

and the truth table isn't too difficult to construct (X=F):

I said that the minterms are m0, m1, m3, m5, and m7, as F is 1 in rows 0, 1, 3, 5, and 7 of the truth table above.

But the textbook says that the answer is m0, m1, m2, m3, m6, m7. What am I missing here?


texts: What is the difference between galvanic skin response and skin resistance of human skin?

texts:
I know this is not related electrical directly, but op amps and Wheatstone bridges are used in these applications.
I have seen, Wheatstone bridges with a  differential amplifier are used in skin resistance measurement.
The following will provide skin resistance in Ohms:

Galvanic skin response is measured with an op amp as well:
Schematic source.

GSR- I could not find whether it is resistance or some other parameter. Some say it is a measure of skin conductivity.
What is the real difference of these two readings? Are they the same?


texts:
I have looked all over the interwebs for a few good hours now, and I cannot find anything that simply explains a capacitor! I know that the capacitance of a capacitor is measured in uF, but what is the voltage of a capacitor? I have a small, hobby capacitor at my house and it is a 100 mF 16V capacitor. What is the difference between that and a 10uF 16V capacitor?

Schematic:

simulate this circuit – Schematic created using CircuitLab

So, as you can see the 2 caps are the same. If you charged part of the cap with fruit 1, as in Circuit 1, and then took out fruit 1, and replaced it with fruit 2, as seen in Circuit 2, without taking the cap out or discharging the cap, will the cap have 1400mV?


texts: How to connect a Inductive Proximity Sensor Switch NPN DC6-36V to PIC18F4550 5V

texts:
I have got a LJ12A3-4-Z/BX Inductive Proximity Sensor Switch NPN DC6-36V with this Specifications:

Model: LJ12A3-4-Z/BX
Theory: Inductive Type Sensor
Wire Type:    Cylindrical DC 3 Wire Type
Output Type: NPN
Detecting Distance: 4mm
Supply Voltage: DC6-36V
Current Output: 300 mA
Response Frequency: 100Hz
Detect Object: Iron

(I use 12V or 8V to supply one sensor)

this should be connected to this ports of a pic (one sensor per limit):

what do I need optocouplers etc.?


texts: Why does my op-amp circuit output a rectangle wave form instead of sine?

texts:
After tons of research on the web I still don't know what the problem is.
I'm trying to simulate a non-inverting voltage amplifier.  It is supposed to generate a similar waveform but when I use the oscilloscope I see that the wave is a rectangle not a sine wave.
Can someone explain what is wrong?
The first picture is wrong I know but it is just for experimenting the op-amp.


texts:
So i have this shift register

With the initial values of ABCD (1101)

And the question is, how will this change after 4 clock pulses.

As I understand it, this shift register goes shifting the values from left to right. My first guess was basically taking the the lsb and putting it in first place and repeating the procedure 4 times (4 clock pulses).

I would then get ABCD (1101)

This is not the correct answer though.


texts: Cooper Bussmann's screw-in Edison-base mini breakers aren't for inductive loads. What does "inductive" mean?

texts:
I'm thinking of buying some Edison-base screw-in miniature circuit breakers to replace some of the fuses in my house.  There are some made by Connecticut Electric and some made by Cooper Bussmann.

Cooper Bussmann writes that their Edison-base mini breakers aren't for inductive loads.  I don't know too much about electricity.  What does "inductive" mean?


texts: A few years ago I found an old Peavey Standard 260 and I just took it apart for parts. I want to try to use the transformer for something, but don't know anything about it.


texts: Linear Feedback Shift Registers on FPGA's

texts: I want to put 256 linear feedback shift registers on a FPGA and each LFSR will have just two tap positions for the XNOR feedback and each register is 63 cells . I don't care if the LFSR'S are not maximal length. The catch is I want the tap positions for all these shift registers to be easily reconfigurable. How difficult/easy is it to do this?


texts: How NOR gate turns two zero inputs into one as output?

texts: While wrapping my head around NOR gate, I found it difficult understand. Not in terms of the logic, but how it works from electrical perspective. I always like to see electrical current as water stream in a river. When you have water in the river, let's call it 1. If there's no water, let's call it a 0. It's fairly easy to understand that you can block the flow to make 1 to become 0 with a gate. But how exactly does it work when it's coming from turning two zeros into a one? It seems odd to me that you can turn two of "nothing" and output "something". When two low voltage as zero digital signal turn into a high voltage one, where's the energy coming from?


texts: How do you deal with operating ranges of low current LEDs?

texts:
I'm looking at using an IN-S85AT5UW in an upcoming hobby project.  I'm pretty sure it says that with the white LED, I'll get about 180 mcd and that the maximum continuous forward current is 5ma.

That feels surprisingly low, so I thought I'd get a sanity check.  It also kind of makes the forward voltage range a bigger concern I think.

I have a 5V supply and if the LED has a typical forward voltage between 2.6 and 3.4, then I'll have to drop 2.4V to 1.6V across a current limiting resistor.

So, somewhere between 320 and 480 ohms?  That seems like a pretty big range.  If I get an LED with a forward voltage of 2.6V and I have a 320 ohms resistor, then I'll have a 7.5ma current . . . which is 50% higher than the rated forward current.

Do I pick conservatively and accept the loss in brightness?  Do I pick a resistor based on the nominal forward voltage of the LED (3V) and hope I don't burn out the LED?  Are the datasheets written so that if you select components at nominal values, the component will not burn out over its rated min/max range?


texts: Applying power to a circuit only when a certain input voltage has been reached

texts:
I'm playing around with an old MagSafe charger and designing a circuit to be powered off it.

From what I've read, the charger's safety mechanism first provides 6V with a current limit of around 100uA. The load is expected to apply a resistive load that pulls that voltage down to around 1.7V for a second or so. This seems to be some sort of protection against shorts (i.e. a short would have pulled the voltage close to 0V). Only after one second and the charger is happy there is no fault does it then send the full 14-20V down. It makes sense to do this since the 85W of power the charger is able to deliver is something that can seriously ruin your day if shorted.

Unfortunately, that means extra complications if I'm designing a circuit to be powered entirely off the charger. In particular, I don't want to provide power to the rest of my circuit until the charger is delivering full power.

I came up with a scheme to achieve this by taking advantage of a N-channel MOSFET with a high threshold voltage to do this.

simulate this circuit – Schematic created using CircuitLab

When VIN is at 6V, M1 will not turn on and R1 will be the only load being driven (which will pull down the voltage as per the spec). When the charger starts delivering the full voltage (around 14-20V), VIN will be above the threshold voltage of M1 which will deliver power to the rest of the circuit.

Now, in practice, I understand that a MOSFET is not really completely off if a lower-than-threshold-voltage is applied to the gate. Normally this isn't a problem but in this case, I can't really leak more than 100uA into the rest of the circuit lest the safety circuit thinks there's a short circuit.

Will this actually be an issue? What parameter should I look for when shopping for MOSFETs? Is the idea sound or have I missed something blatantly obvious?


texts: How can emitter bias amplify since the emitter current is fixed?

texts:
My textbook says \$I_E\$ is fixed at \$V_{BB}/R_E\$ no matter what the current gain of the transistor is. This is confusing me a lot. Since the emitter current cannot change, how can this ciruit amplify anything ?

When I feed in some signal \$v_b(t)\$ to the base, I think it simply appears across the \$R_E\$, emitter current would then be \$(V_{BB} + v_b(t))/R_E\$. See no amplification ?


texts:
I'm trying to calculate $$\frac{V_o}{V_s}$$ of the given circuit, but don't really know what to do with the voltage dependent voltage source. As I'm not an engineering student, this stuff is very foreign to me and I don't know how to approach a problem like this.

Also, what type of filter would this be? To me it looks like a high pass filter, but am not sure.

Any help is much appreciated!


texts: Reverse-engineering asynchronous serial protocol for EcoSmart Tankless Water Heater

texts:
I am trying to reverse-engineer the remote control protocol for my EcoSmart Tankless Water Heater.

Unfortunately, the remote control device is no longer available for purchase, and the manufacturer has no information on the protocol used.  I want to try and interface the heater directly to an Arduino so I can monitor/control it via Ethernet.

The heater has a 4-pin connector for the remote, and is connected to the MCU as shown here:

simulate this circuit – Schematic created using CircuitLab

The unit sends data in the following scenarios:

Temperature changed by turning control knob
Unit turned on/off by pressing control knob
Heater activated/deactivated (water flow start/stop)

My scope has built-in RS-232 decoding, and it does seem to decode some data at 1200bps, but I am not sure I'm actually dealing with RS-232/UART data here.  My question to you is: what type of data does this look like to you?

Here is part of the output of an "ON" operation (i.e. press button to turn heater On): http://is.am/fx

To me, this looks like too many high/low transitions for UART...  I am leaning toward a variable-width pulse to indicate 0/1. In the timing diagram above, you see my interpretation of both RS-232 and "Other" which indicates an unknown protocol, which would have a digital '0' as a 720uS high pulse, and a digital '1' as a 24mS high pulse.

I would appreciate any insight into the protocol used here.  If you need clarifications I'll do my best.

RS-232/UART reference: https://electronics.stackexchange.com/a/227414/16378

Update:
After recording and transcribing lots of waveforms from different events, I have figured out part of the protocol.

There is a 'Start' command at the beginning of each sequence.  It consists of a logic Low for at least 4ms, then High for 7ms, then Low for 4ms.
After the 'Start' command, short pulses (720uS) represent logic Zero and long pulses (2.4ms) represent logic One.  The spaces between pulses are all approx 840uS.
All sequences are 5 bytes long, and are transmitted 6 times.
The first 2 bytes are always the same: 00:FF:0F:F0
The third byte appears to be the command/event identifier:

Temperature setting change event (wheel turned): 00:70
ON command (button pressed): 00:00
OFF command (button pressed): 00:70 (same as temp. setting)
Flow start event: 02:70
Flow stop event: 00:70 (same as temp setting and Off command)

The fourth byte is the temperature in Fahrenheit, MSB to LSB (80 to 140)
The fifth byte is the temperature in Celsius, MSB to LSB (26 to 60)

So now I have to determine if I can send these same sequences into the RX line to change temperatures and enable/disable the heater remotely.  I wonder if a different address is used

UPDATE #2: Success!
It turns out, sending the same sequences to the RX pin can be used to adjust the temperature and turn the unit on and off!  It was quite easy to bit-bang the protocol with an Arduino Uno, and the heater responds to temperature settings by directly altering the output temperature (no need to step upward/downward one degree at a time).
I plan to post the full interface guide along with source code for both input and output when completed.

Thanks to everyone who offered suggestions!

UPDATE #3: Github repository created:
https://github.com/ryangriggs/EcoSmartLib

UPDATE #4: See Phil's github repo for further info: https://github.com/PhilRW/ecosmart-remote


texts: How to determine which size of surface mount resistor for an ADMP441

texts:
I'm relatively new to reflow surface mount soldering and am unfamiliar with the various sizes of components.

The PCB design I ordered is here:
https://oshpark.com/shared_projects/ypqAU3CH

But I don't see any reference to which size components I should order to fit the design.  (ie 0402 0603 0805 1206)  In this case, I suspect that the correct size is 0603...but I don't want to order parts on an educated guess.

How can I determine the correct size of components to order for any given board design?


texts:
I have an LM35DZ which is temperature sensor, properly connected and reading
strange values... like 1023.

I've tried almost any code I could find regarding LM35DZ and Arduino, with the same results every time.

After several attempts I tried to measure voltage with multimeter on 2nd pin (Vout) and it was 4.16V. Using this code I also got 4.16V precisely :

float voltage0 =   analogRead(A0) * (5.0 / 1023.0);
Serial.print(voltage0);

By mistake I ordered 5 pieces instead of one so I tried with all of them and they all give me same result (both on Arduino and voltage measured).

Now I'm confused what is going on and why all of them return the same value?

Here are pictures:

Schematic used http://blog.rastating.com/content/images/2014/Feb/lm35_schem_1_.jpg
Update:
Sorry on my Bad English, I'll try to explain even more what I've done.
As Ricardo told I've tried to remove Arduino out of picture and still got 4.16V,
on all 5 of them.  (bought them from Ebay- maybe got defective/miscalibrated ones? )
Will buy one in local electronics shop and try with it.
Attached schematic picture.


texts:
I am trying to measure the current consumed by my circuit using an MDO4104 oscilloscope. I have soldered a 0.01 ohms resistor in series with the Vcc. The 2 ends of the resistor is are probed using 2 different probes of the said scope. Then I am using the math function of the scope to do a difference. Then this difference value is divided by the resistor value (0.01) to give me the current. The selected resistor is of 10W. I am expecting something like a peaks of 10Amp or so.

Now the 1st end of scope is Vccb (blue) and the other end is Vccg (green). Ideally Vccb > Vccg.

simulate this circuit – Schematic created using CircuitLab

In the oscilloscope I am doing a math operation of Vccb - Vccg. Ideally I must divide it by 0.01R. I understand that. But just the difference should be very small is what I assume. Just for me to analyse the drop across the sense resistor.

The scope screen shot is as shown below -

Please note I have removed the dc bias of 24V to analyse the voltages carefully. Is this analysis or method correct ?
Also, if you notice the peak (red). It shows almost 0.25V (scale is 50mV). So, the current at that instant is 0.25/0.01 = 25Amps. Now, I am using just 2 22AWG wires for this. 22AWG can source a max of 7Amps/wire. So we get a max of 14Amps sourcing via the wires.

If so, why doesnt the wire burn out or get damaged ? I understand that this peak is momentarily. If so, what is the max time that this wire can sustain till it burns out (if we continuously supply 25Amps).

How do i calculate the max time for sustaining the 25AMps of 22AWG(or for that matter any gauge) wire.


texts:
I recently purchased three 12V batteries: #1, #2, and #3.

They all say that they have T1 terminals; however, when looking for the appropriate connectors for my 18 AWG wire, I could really only found information about F1 and F2 terminals.  Based on this page, two of my batteries definitely have F2 connectors and one definitely has F1 connectors.

So what's the deal with T1 (and T2?) versus F1 and F2?  Are they the same?  Perhaps T refers to the wire connector while F refers to the battery terminal?


texts: Are there Eagle library templates for each package type?

texts:
Although some packages vary slightly from one-another, nearly all of them have the same PCB footprint and schematic symbol.

How do you guys actually make the footprint, for say, an LM317 TO-220 when it is not (at least by default) in the library?

I assume from scratch as I cannot see a "copy from another item" feature at least on hand, however that opens to major problems if one was done wrong.

I have heard of a default template library of most package types, that'd be amazing to use, however have not found it (or on search engines at first look) nor would I understand how to copy just (i.e. a TO-220 generic) template out and edit it in to my own library.

Any advice on what to do?

I may need to get a lot more proficient at this, as many parts I come across simply do not have libraries. I thought Element 14? (who bought cadsoft I believe) would have made a huge library with every one of their parts - that'd be amazing, again, no luck in search engine and am not even sure it is better than just DIY symbols.


texts:
I am trying to design a Pi Hat to integrate my Raspberry Pi 3 for use as an automotive head unit. I have a Texas Instruments TAS6424 and some supporting components, and am trying to design a DAC PCB to drive the speakers.

Ignoring power issues etc, the issue I've run into is that the Raspberry Pi cannot output the mclk signal required by the TAS6424 chip's digital serial audio interface. The DAC operates in slave mode exclusively, while the Pi can operate in either master or slave mode on both the LRCLK and BCLK signals.

I've found the following devices that may be able to generate an appropriate signal.

TI PLL1708
TI SN74LS294

Will this work to generate an external clock? Can the Pi generate a BCLK signal from a LRCLK? Vice versa? How much kernel modding will it take to properly control the above devices in order to switch sample rates at runtime and create a working ASoC device?

Developing something like this would allow one to interface the Pi with DACs that require a master clock signal, like most hifi i2s equipment.


texts: Is the ability of reading NFC-tags in smartphones specified?

texts:
Is the NFC-reading-module in smart phones in a way specified (e.g. in ISO 18092) as that every smart phone has the same 'power' of reading NFC-tags. I am not an electrical engineer. What I am trying to ask is, if the reading process in respect to the distance between the smartphone and the NFC-Tag is the same at every smart phone because every NFC-reading-module is the same, or if there are differences between smartphones as that one smartphone can read tags where the difference is like 5cm and another one can read tags with distance to the phone about 10cm?

I hope my question is clear. It is a little bit hard for me to phrase.


texts: Which option of bonding multiple strands from Cat5 pick up the lowest level of EMI?

texts:
Caviat
I am not an EE major, nor have I had the opportunity to study general EE principles. At best, I could be considered a weekend hobbyist. This is my first time posting to this SE site.

Some background:
I have a microcontroller that I have programmed to monitor for change in state on a circuit. A good analogy would be a alarm circuit. When there is a change in the state, I will perform some action. I have this circuit set up as a working prototype. I am planning on using Cat5 for the loop of cable for the monitored circuit. The area in which the controller and circuit will eventually be placed has the potential to be a somewhat noisy environment from an EMI perspective.

Okay, what is the question then?
If the eight strands in the Cat5 were to be bonded together into two legs to carry low mA DC current, is there any advantage to which 4 strands are connected from the perspective of lowering EMI that is picked up by the wire and transmitted back to the microcontroller?

For reference the pinout for Cat5 cable is as follows:

Each white-dash wire and the solid colored wire of the same color are a twisted pair.


texts:
I want to start with the RFID by building up a simple lock which can be unlocked with another RFID transponder.

The device which has unlocks the lock and has one RFID transponder will be a BeagleBone Black. I would like to have the key as some static RFID transponder (sends only its key).

To achieve this I have following questions:

Is it possible to connect a RFID antenna and control it just with GPIO and PWM or does it necessarily require an own micro controller
What protocol is used for data communication between the RFID transponders
Where or how do I set a key on a static RFID transponder
Are there any resources I should read additionally?


texts: Measuring isolated AC signals with a single ADC that has common ground inputs

texts:
In my setup I have a power transformer (XFMR6) and some load connected to it.

Need to build a device that takes samples of U, I at the input and output of the transformer.

The measuring networks have to be halvanically isolated from the current networks. I plan to use ACS712 for the current sensors and I have no problems with it.

To make voltage measurements I plan to use small transformers (XFMR3 and XFMR4) connected to ADC that has only single ended inputs with a common ground. Will there be problems if the two signals come in different phases? What if there will be no grounding?


texts:
Is it possible to have two antennas connected to the antenna port of an RF transceiver through some sort of mux? I want to be able to switch to a different antenna if the signal is weak on one.  I would just use two of the RF modules but they are somewhat expensive.

ant2-----------------------------                          |---------|
                                 \________|2:1MUX|_________|RF module|
ant1-----------------------------/                         |---------|

edit:
this will be for a 500-900Mhz system
and both antennas are oriented differently, the case isn't that one antenna is high gain and the other not.


texts: How much volt and amps would be in this CT circuit?

texts:
How many amps would be in Is?
How many volts is Vs?
Does that voltage depend on te number of turns like current?
Can I operate a 24VAC or DC relay from it?


texts:
I'm trying to build a LED driver using an MC34063 dc-dc converter in step up mode. Since LEDs need current mode operation to run stably, I elected to use a 51mOhm current sense resistor combined with a current sense amplifier, ZXCT1109, to output the required 1.25V feedback voltage (normally done with a voltage divider to measure output voltage). I also used an external n-MOSFET so that I'd able to potentially operate at higher average currents like so:

simulate this circuit – Schematic created using CircuitLab

Where R1 is a pull up resistor.

Specs:
Input voltage: 3.6V
Output voltage: ~6V (2x Cree XM-L LEDs in series, forward voltage drop ~3V)
Output current: 0.5A (for testing purposes, ideally ~1-1.5A)

I tried this out, and it worked... Somewhat. There is audible buzzing from the inductor and the MC34063 gets hot pretty quickly, which shouldn't be happening. In addition, despite an expected input current of ~1A given the boost ratio, the power supply's current limit of 2A is being exceeded for part of the cycle - there's an LED that turns on when the current limit is tripped and it's partially on, flickering a little, even though the (analog) current dial indicates ~1A. I imagine this is due to very high input voltage & current ripple.

The datasheet seems to suggest the IC normally operates in discontinuous mode, which would explain the ripple. I am fairly sure it would be better to run the LEDs in continuous current mode: a high output voltage ripple would lead to massive current ripple since the load is an LED, and efficiency is a big concern. Higher ripple current would also put a lot more stress on the switching components as well as making the inductor more likely to saturate.

Question 1: Is there any way I can force use of continuous current mode? Is this what I should be looking to do?

In the process of writing this I realized that the current path during the SMPS on time is also through the internal BJT, which nullifies the intended effect. Ideally the BJT should be driving the MOSFET such that the MOSFET carries the inductor charging current.

Question 2: Is there any way I can configure an n-MOSFET so that the BJT will drive it without carrying the inductor current? Or must I use a p-channel?

Addendum:

There is a 12V zener diode (only rating I have) between the output
and the feedback voltage pin to protect the IC in case the load is
disconnected.
Originally I only used 2 10uF MLCCs to filter the output. In my haste I ignored the required output capacitance calculations, and after going back over them I realized this was approx. five times too small. I added a 100uF electrolytic cap and this seemed to reduce the ripple current, but it's still very much discontinuous. Is this the right way of going about it? 120uF seems like a lot of capacitance for a power supply of this size.


texts: How does the improved transistor astable multivibrator work?

texts:
This is an astable multivibrator circuit. Assuming that TR2 is initially on, the right pin of C2 is grounded and since C2 isn't charged, the left pin of it is also at 0V. Now, Out 2 is low.

C2 is then charged up slowly through R3, until a critical moment when the left pin of C2 passes around 0.7V to activate TR1, in which the circuit flips and TR1 turns on, causing Out 1 to be low, and the cycle repeats.

However this has a problem with the rise time. Assuming that TR2 is initially on, TR1 is off and thus Out 1 will be high. However, the capacitor will cause the rising edge to be a curve and not "instant".

This is an improved astable multivibrator circuit, which improves the rise time by using a diode to prevent the capacitive action when TR1 is high (assuming TR2 is initially on). Instead, C1 will be charged through a separate resistor.

It works in real life, but I just can't wrap my mind around it. If D2 is there, and TR2 is on causing the right pin of D2 to be grounded, the left pin of D2 will be around 0.7V (forward voltage drop of D2). As C2 is not charged yet, the right and left pin of it will be 0.7V.

But doesn't this cause it to achieve the critical level of 0.7V already? This is where my head explodes from infinite frequency.

How does it work?


texts: How can I switch a single load (fantastic fan) between two separate 12v power sources (the vehicles 12v battery or a goal zero power source?

texts: The fan is currently wired into the vehicles 12v system and drains the battery on multi-day trips. I plan to wire the fan into the goal zero system, but I’d like have the option to switch between the two systems (for example: I’d like to switch back to the 12v battery system when the goal zero isn’t in the vehicle.  Can I use a switch to provide either power source for the fan?


texts:
Please excuse the possibly simple question but this is all a bit new to me.

I have an APC Smart UPS 1000 which has a very large/tall 2700uF 40V capacitor on the battery (24V) connector. Not knowing how good all the capacitors are and having already ‘melted’ a set of new batteries, I have exchanged all of the electrolytic capacitors on the board as this is recommended to resolve overcharging problems.

The problem is that the new 2700uF 40V electrolytic is TINY compared to the original.

Does it matter?
Surely a 2700uF 40V cap is still a 2700uF 40V cap no matter how big it is? Or is there a reason why the old cap would have been spec’d To be BIGGER?

OK, a bit more information which, hopefully, will get me closer to a solution...

Thanks for your answers.

The original caps are EPCOS B41848-A7278-Z which is TDK, from what I can find online. The problem is that I can not find a spec sheet.

If anyone knows the specs for these caps, can you let me know please?

Or

I have found some Nichicon GU series caps at RS which match the snap pin dimensions. They are 50V rather than 40V but, otherwise, are 2700uF.

Does anyone know enough about APC Smart-UPS design to be able to say whether they are suitable?

Or

Point me in the direction of somewhere where I can buy the correct/matching caps?


texts: Waveform Function Generator - Practical Usage

texts: I never had any chance yet to play with function generators, but I know what they. What I don't see at this moment is their practical usage in digital electronic. For audio I can see it probably for comparison of how good or bad your amp is by comparing the outputs for example, and for digital I saw that some of these function generators can record a digital signal, and later reproduce it on demand and in that case they would act as simulators (right?), but what would be some other practical scenarios?


texts: How to drop input voltage to an L7805 using a zener diode

texts:
I want 5 volts for my circuit but my rectifier gives me a voltage of 17.30 volts. I am using an L7805 regulator for all this and I want to use a zener diode on my adjustable pin of my regulator so as to decrease the amount of voltage going in my regulator.

How do I do it without blowing my regulator?


texts: Looking for the name of a 3-input logic gate

texts:
I am looking for a three-input, one-output logic-gate from the following truth table:

$$\begin{array}{c|c|c|}
\text{C} & \text{B} & \text{A} & \text{Output} \\ \hline
0 & 0 & 0 & 0 \\ \hline
0 & 0 & 1 & 1 \\ \hline
0 & 1 & 0 & 1 \\ \hline
0 & 1 & 1 & 0 \\ \hline
1 & 0 & 0 & 1 \\ \hline
1 & 0 & 1 & 0 \\ \hline
1 & 1 & 0 & 0 \\ \hline
1 & 1 & 1 & 1 \\ \hline
\end{array}$$

As I can see \$A\$ and \$B\$ acts as XOR-gate when \$C=0\$, and as a XNOR-gate when \$C=1\$.
Im looking to order a gate that has these input- and output pins, and the required operation pins to make it work. Im just wondering whats the name of the gate? Looking for one in the 74 or HC family, or one that is easy to put on breadboards.


texts: Is the infrared sensor fabrication process(Using such materials HgCdTe, InSb, InGaAs) different from CMOS fabrication processes ?

texts:
I want to learn differences between Infrared sensor fabrication and standard CMOS IC fabrication. If I am not wrong, in standard CMOS fabrication Silicon is mostly used. But for infrared spectrum such materials (HgCdTe, InSb and InGaAs ) are preferred.

Thank you,


texts: Would this type of design be scale-able?

texts:
With current technologies within a modern system, we have pushed the limits of computations within the CPU portion of the system where it now exceeds that of the memory units. Moving memory is slow and costly and this trend grows as datasets increase in size. The bus between the CPU and Memory is very narrow and this creates a bottleneck as well as higher power consumption.
We can have a CPU perform 3-5 billion instructions per second where its base clock frequency is measured between 3-5GHz, yet when we have to fetch data from main memory across the bus to the system's CPU this is now orders of magnitude slower creating various bottlenecks.
Instead of having a single CPU with an ALU and an array of memory cells that communicate across the system's bus independently, what I propose is to couple both the ALU process and the memory unit into what I like to call a single ALU Memory Cell.
The I/O of this device has the following structure:

Inputs:

Three single input bit lines.
A clock signal.
A 4-bit instruction opcode.

Outputs:

The three input bits as a fallthrough output.
The three inputs after being latched to a single bit register (history).
The two output bits that the resulting operation performs.

Here's a Logisim image as a diagram to my ALU Memory Cell. This could easily be extended into a 2x2 array of cells to create a full memory module. The columns would be single bits to a word, byte, etc. And each row would be a word line as convention systems already implement.

With this kind of implementation design in hardware, this could allow for in-place calculations on data without having to move the data. This could reduce latency, power usage, and even cost.
My main question(s) of concern is, would this be scale-able and a viable proposal to the solution of reducing memory latency and power consumption within a system?
In other words, instead of having a single CPU that communicates to a memory bank via a single bus, would we be able to decouple and integrate the two into a single unit or device by merging these technologies where each memory cell has its own ALU. Here calculations can be done in place on a set of bits. Yes, there are 4 single-bit registers, a full 1 bit ALU a single 4-16 mux, and a 2-bit output register per cell technology. This might have the potential to reduce the amount of memory(data) transfers as calculations and instructions can be done in place without having to move the data. Instead, we would move the instruction to the memory banks.


texts:
I am using UCC21732 gate driver IC. This has an external miller clamp, meaning the "Clamp" pin must be connected to the Gate of the external MOSFET. However, I want to build my own miller clamp without the external clamp MOSFET.
So I looked at what an "internal miller clamp" does. I found this document showing the internal diagram in detail. My question is -- Is the "Vclamp" simply a voltage source? Like, a cell battery? In other words, if I were to compare the voltage across gate resistor, how do I get the reference voltage? Should I be using something like a resistor divider?

EDIT:
I want to implement the active miller clamp without using the clamp pin in the gate driver. I have tried out using a pnp/npn transistor, but that is only to pull down the gate voltage to ground. Any suggestions on a different method is appreciated.


texts: From node to node, do units of charge lose energy over a constant period of time?

texts:
I have the following circuit set up on a breadboard, and I've measured current and voltage between each node. Current everywhere is .02A, as expected, and my resistor came out to 217R.

simulate this circuit – Schematic created using CircuitLab
As per the above schematic, voltage across the LED came to 2.25V.
This is a bit confusing to me. Apparently, voltage is joules per coulomb. So, I assume:
From positive lead to anode, there are ~6.66 joules per coulomb

From cathode to the start of R1, there are ~4.41 joules per coulomb
In other words, every coulomb that went across the LED lost ~2.25 joules.
How long did it take for every coulomb to lose 2.25 joules? Did it take a unit of time for every unit of charge to lose that amount of energy?
Would it be something like:
R = L/T
R = rate of L per T

L = loss of energy

T = time for a coulomb to move from anode to cathode
However, this seems flawed to me, the notion that each coulomb would lose energy at a set rate, since current (or, movement of charge over time) is constant throughout the entire circuit. What am I misunderstanding here?
Edit
When an LED is rated at .02A and 2V for best performance according to the manufacturer, does that mean the circuit needs to be set up in such a way that movement of charge over time is equal to .02A across the LED, and that each coulomb must lose 2 joules between the anode and cathode?
Or, does it simply mean that the amount of energy it takes to move a coulomb from anode to cathode must be equal to 2 joules, or else the LED will be damaged over time?


texts: Finding the equivalent inductance across terminals a and b with a wire included

texts:
Find the equivalent inductance looking into the terminals a and b of the circuit below.

(Answer: L(eq)= 7H)
Now I try to transform it to be the following.

simulate this circuit – Schematic created using CircuitLab
Then, I get the following formula :
$$
L\left(eq\right)=4+\left(\frac{1}{9+3}+\frac{1}{\left(10^{-1}+0^{-1}\right)^{-1}+\left(12^{-1}+6^{-1}\right)^{-1}}\right)^{-1}
$$
However, $$0^{-1} = Error$$
How do I deal with this question?


texts: Electrically simulate and toggle a capacitive touch

texts:
I am interested in testing a capacitive touch device for reliability by simulating touch events periodically.

I would like to do this purely electrically if possible (no mechanical parts), or with a mechanical relay. I would like to avoid servos, motors, etc.

How can I design a circuit which can switch between two states? In one state, it would generate a touch on a capacitive device, in the other it would not.


texts: Finding the steady state value of v using nodal analysis

texts:
I am currently working on a problem of determing the steady-state value of v using nodal analysis. I understand all the steps up until the step of converting my j6 / -1-j to the phasor value that I circled within the red rectangle below.

Could someone give me some insight on what was achieved here and why?


texts: Reference voltage source using classic rectifier diodes

texts:
I want to make some simple voltage stabilizer using operational amp, but need source of reference voltage. I know that I can buy this component, but shop is far away from me and paying 8e for courier to deliver component with price of 0.00000000...x seems to be overkill. And diodes that I have can be counted by hundreds.
In theory from school, each diode have a voltage drop on it, should I use them few in series with rezistor or are there some aspects that I do not know about and why this solution is bad or very bad idea ?


texts:
I have a digilent Nexys 4 board that I am using for learning Verilog. I have written a code that requires connecting an audio speaker to the board for evaluating. What is the speaker that can be used for Nexys 4 board?
Nexys 4 manual: http://www.cs.unc.edu/~montek/teaching/Comp541-Fall14/Lab/Nexys4.pdf


texts:
Firstly, I have to say that I'm new to PIC family. I am trying to build USB-CAN converter from USB-TIN page using PIC18f14k50 microcontroller, PICkit3 programmer and MPLAB IDE.

After writing hex file to flash memory device is not detected by PC. I tried on different OS and PCs.

I decided to read back flash memory after writing. It turned out that hex file that I've read is different from what I've tried to write!

What have I made wrong? Any ideas?

what i read before write

what i write

Look at my hex files. I read a lot of "FFFFFFF..FFF" sectors. Some adresses and data are consistent, but only just a few.


texts: Is there an alternative to B2.SPICE A/D for Mac OS X?

texts: I've tried B2.SPICE A/D on Windows and I liked it. Is there an easy-to-use application like B2.SPICE A/D that uses SPICE and allows drawing the schematic of the circuit and simulating it?


texts:
I'm designing an intermittent wiper motor controller to be fitted on a classic car.
As I'm selecting components, I came around this relay that seems to be fitting my needs (PCB mount, automotive, high current).
When looking at the PCB layout, I find pin 3 and 5 way too close to each other to allow for drilling plus some copper around the holes for soldering.

This makes me think I can't use this relay as I need wide copper path for the current demand (20A). I'm not familiar with relays, am I missing something ? I find it strange that it is designed that way.


texts: Converting varying frequency and duty cycle to varying frequency fixed duty cycle

texts:
I have an LM331 which is outputting variable freq. with an input of 0-10V. The output freq. of LM331 is is varying between 50Hz to 900Hz. But the pulse width creates some trouble for the next stage. Around 50Hz the ON time is too long; and around 900Hz the ON time is too short. I want more equal ON OFF time in any case(anything between 30 to 50 percent duty cycle would be fine).

I tried with a 555 one shot topology but that didn't help. It just fixes the pulse ON time. That means it only solves the problem if the incoming pulse width was fixed.

But in my case both the freq. and the pulse width changes.

So I basically want to keep the freq. same(or halved) for an input voltage with a more even ON OFF time(duty cycle around between 30% to 50%) at the output. Some suggested using 74HC74 for the purpose but I have no experience with that. I couldn't find a similar application. How can I solve this issue without using a microcontroller?

To be more clear I need the variable frequency output from the LM331 have 50% duty cycle at any freq. output. Frequency will vary as usual linearly to the 0..10V input; but the duty cycle(ON_time/Period ratio) should not vary much(fixed at 50% or 30% to 50% would be fine).


texts: How nickel plated copper strip can be welded? What is the optimum thickness of nickel layer?

texts: I have a trouble with (resistance) spot welding of nickel plated copper strip to 18650 battery. I tried to weld 0.1mm, 0.2mm and 0.3mm copper strips with 5 micrometers and 10 micrometers nickel plate thickness. Actually i have tried all of the combinations, that is i have tried to weld 0.1mm with 5 microns to 0.3mm with 10 micrometer or 0.2mm with 10 micrometers to 0.1 with 10 micrometers… Additionally, i adjusted power of spot welding machine, i tried with full power and half of the maximum power… Unfortunately all of the trials have failed. According to you what is the main problem in my case? What is the optimum nickel plate thickness for spot welding application and how it is determined?


texts:
I wand to make a simple stereo 4-band EQ for a mid-fi amp I'm building. I draw my knowledge from this excellent article - however, it only seems to talk about peak/notch bands and not low and high pass filtering in the context of a graphic EQ.

Could anyone clue me up on circuits for a low-pass and a high-pass band which would fit well in a design such as this?
How can I adapt the schematic to work with 20k pots instead of 100k?
What are some good center frequencies for my EQ?


texts: what is the difference between area and magnitude of a pulse?

texts:
I have read : "An impulse is a generalized function having infinite length and finite area. It is also known as the Dirac Delta function. Magnitude of an impulse doesn’t make sense , only its area does.

A pulse is defined over a finite time interval. Both the area under the pulse and magnitude of a pulse at an instant of time is well defined."

What is the difference between area and magnitude of a pulse? what do they physically mean? and is there a relation between them?


texts:
The problem has given the following circuit:

And asked to find the value(s) of Ix if the elements absorb the power(s) given.

I tired to set up KCL/KVL but I keep getting stuck.

I first drew this:

And set KVL1 = (Ra)(i1)-(Rb)(i2)
        KVL2 = (Rb)(i2)+(Rc)(i3)

After that I am confused on how to continue without knowing the resistances.


texts:
What will happen if transformer core is made of aluminium which is a paramagnetic material?
I know transformer core is made of iron which is a ferromagnetic material. The reason is a small amount of magnetizing current can produce a thousands of times magnetic field inside the core.
This was asked in a interview. Please clarify this.


texts: How is the electrical bus capacitance for I2C trace calculated?

texts:
i am trying to learn how to calculate the bus capacitance of an I2C tree with a master and multiple slaves.

For example, in this document from TI, it shows how to calculate the value of the pull up resistors and just assumes the captive load of each bus line to be 400 pF.

Where do I get this pF number in my i2c design?

What I can think off is two sources (what am I missing?):

I need to look up specs of all slave devices and add up their Capacitances to be in parallel, right?
The second source would be the I2C trace itself, right? If my trace is let's say 6 inches long, how do I calculate the capacitance of this trace?


texts: Show A Non-Min Phase System Cannot be Controlled via Controllability Matrix?

texts:
I've been reading about how a non-minimum phase system with a Right-Half Plane Zero and Right-Half Plane Pole can become impossible to control IF the RHP Pole becomes faster than the RHP Zero.
I was curious if one can show such a system is uncontrollable via the Controllability Matrix.
I was starting with the following system.
$$ G(s)=\frac{s-z}{(s+p)(s-p)}$$
However, I was tripping up on how to convert that to State Space Form, so I can get the A and B matrices and then obtain the Controllability Matrix.
Curious if anyone had insights.  Thanks!


texts:
Given the following Hamming Code, I was tasked to implement the following circuits using gates.

Transmiter Circuit (Parity Bit Generator).
Error Detector Circuit of the receptor (Parity Check).
Data Bit Corrector.

I did the first two circuits, but I can't seem to figure out the corrector circuit.

Parity Bit Generator Circuit:

Parity Check Circuit:

I was hoping for a little push to help me finish the rest of the circuit.

Thanks in advance.


texts:
Really quick question here - is it possible to use the GND/5V from the USB cable to power the Arduino through the USB connector but use the RX/TX pins to a motherboard's USB pin headers (D+/D-)?

The D+ = TX
The D- = RX

Then connect the common grounds (5V, GND and motherboard GND together).

So:

5V (psu) ---------> Arduino USB \$V_{cc}\$ connector
GND (psu) --------> Arduino USB GND connector
TX (Arduino pin) -> motherboard USB header D+
RX (Arduino pin) -> motherboard USB header D-
GND (Arduino pin -> motherboard USB header GND

Will the GND pin on the Arduino be considered "combined" since the PSU GND is connected via the USB connector (grounding both USB GND and motherboard GND)?

The Arduino I am using is this:


texts:
I have the following flash section defined in my linker file:

keep { section .SomeConst };
place at address mem: 0x0003F800 { readonly section .SomeConst };

In my code I have the following symbols defined:

#pragma location = ".SomeConst"
__root const uint8_t _value1[16] = {...};
#pragma location = ".SomeConst"
__root const uint8_t _value2[16] = {...};
#pragma location = ".SomeConst"
__root const uint8_t _value3[16] = {...};

Is it safe to assume _value1 will always be at 0x3F800?
is it safe to assume _value2 will always be at 0x3F810?
etc? I assume its not.. but wanted to check with the experts.

This is using EWARM

Thanks
Bret


texts: Connection question for Renology - order and possible converter needed?

texts:
I bought a Renology 100w solar panel with charge controller - and I see in the controller instructions booklet, "Never connect the solar panel array to the controller without a battery. Battery must be connected first. This may cause a dangerous occurrence where the controller would experience a high open circuit voltage at the terminals."
However the solar panel connections for the controller included (looks like a MC4 by this page) show stop, do not disconnect under load. So, which is it, if I set up a portable system I cannot pack it up by unplugging the solar panel from the controller, I cannot pack up by unplugging the battery from the controller either?
What's more, I see the pack I have has an input of 15v, measured on the adapters and this probably will not work seeing the voltage marked 12v on the controller... would that charge it not at all or, very slowly? Would just a dc-dc converter 12v to 15v, to plug be all that's necessary in this case?


texts: Q3.24 (d) Signals & Systems 2ed by A. Oppenheim

texts:
3.24 (d) Determine the Fourier series representation for the following signal:

a_k = 1 (k is even), 2 (k is odd)

The solution (see attached) breaks down the answer to two components:

y(t) and z(t). How is z(t) derived?


texts: Using Arduino to power a 4 terminal phone

texts:
My dad took my battery for misbehaving (No questions!) but I still want to use my phone (Huawei Honor 3c). However, when I use a USB plug, the phone only vibrates constantly (Why does it do this?).

So I looked around and found my Arduino(Uno) and thought I could turn my phone on with this.

However, I found a few problems. (BTW, all info in this image http://vifocal.com/media/catalog/product/cache/1/image/38c4fbe4447791bfb2ff7ebb56cba1e8/h/u/huawei3c_1.jpg)

1) There were 4 terminals. 2 marked with + and - (What are the other 2?)

2) Battery outputs 3.8V while my Arduino has 5V and 3.3V (Which to use?)

3) Is it even possible to try such thing (Could it work?)


texts: Microcontroller with and without debugging features?

texts:
Out of curiousity, are there any microcontrollers which are available with and without debugging capabilities?

I'm asking because I assume that the debugger is not a simple 'peripheral' in terms of e.g. silicon space; I figure it would be much more complex than an SPI, I²C or ADC peripheral.

If that is true, would it make sense to provide 'development' devices with integrated debugging and 'production' devices for mass production? Could the latter be made cheaper because of the omitted functionality?

Are there µC's for which those two variants exist?


texts: Why is this switched power inlet fused on both load and neutral sides?

texts:
I've purchased a Schurter 4304.6090 power inlet for a project and am a bit confused by the fuse configuration. The inlet requires two fuses: one on the load side and another on the neutral side of the circuit. Is this just for redundancy, or am I missing something here?

I plan to use this for 120VAC (USA).

Here's a picture of the inlet, along with a crude wiring diagram:


texts: Excessive AVR static RAM usage with mixed-type math operations

texts:
I've narrowed down an issue in my code which creates an extra 260 bytes of static RAM usage:

BYTE Height = 150;

BYTE sampleLevel(BYTE ADCchan,BYTE averages)
{
    float samp;
    //int samp;
    BYTE level;

    samp = avgSampleADC(ADCchan,averages);
    level = 100-(samp*100/Height);

    return level;
}

BYTE here is a uint8_t type.  If I comment out float samp and turn it into an int type, the static RAM usage goes back down to what I expect it to be.  I suppose this has something to do with the math operation level = 100-(samp*100/Height); but I don't know what it is.  What is happening to create such behavior?


texts:
I am trying to use ESP8266 with STM32L476RG Nucleo. The ESP8266 requires up to 300 mA to transmit properly. I tried to connect my ESP to an Arduino Mega, and it responds correctly, but when I brunch the ESP to the STM micro controller, the AT command was sent correctly, but the response message is not correct (if I send 'AT+RST' the response would be 'AT +RST').

I want to ask if the STM32L476 Nucleo can provide 300 mA that the ESP requires.

If it can require that 300 mA, what do you think the issue could be?

Well, I tried to use an external power supply that can provide 3.3 V the ESP8266 is responding this time with garbage characters baudrate = 115,200 and Tx -> Rx , Rx->Tx, CH-PD -> 3.3 V, VCC -> 3.3 V, and Gnd -> Gnd.

I am working with IARWorkbensh and the code is simple:

if (HAL_UART_Receive_IT(&UartHandle, aRxBuffer, RXBUFFERSIZE) != HAL_OK)
{
    Error_Handler();
}

if (HAL_UART_Transmit(&UartHandle, (uint8_t*)aTxBuffer, TXBUFFERSIZE, 5000) != HAL_OK)
{
    while(1);
}

aRxBuffer is a buffer containing the data received.

aTxBuffer is a buffer containing the command transmitted to the ESP8266 (in my case I'm sending an "AT+RST\r\n" command).


texts: Economical thermocouple amplifier circuit

texts:
I'm looking for the most economical circuit that reasonably accurate circuit for amplifying the voltage produced by a thermocouple (so it can be read by an ADC). For the sake of argument, component count and manual calibration time is not an issue.

It's a K type thermocouple (41uV/ºC) and I'm hoping for an accuracy of around 25ºC from 100ºC to 1000ºC. 1 sample per second is plenty. The ADC is 10 bit, and there is a regulated 12v, 5v, 3.3v and ground supply.

Could it be more economical with the above requirements to use cheap op-amps instead of a purpose made instrumentation amp?

As I understand, the problem with cheap op-amps is their input offset voltage and drift. But am I correct in saying:

Many cheap op-amps can be offset-nulled with a variable resistor?
and the offset drift is relatively negligible even for a thermocouple? (15uV/ºC in the LM741)

If so, the question remains what circuit could be used. Would 3 op-amps be necessary? or could it be done with fewer?

Last but not least, suggestions for which op-amp would be appreciated.


texts: Any thoughts on what this IC might be (from a McDonald's toy)?

texts:
I'm looking for a datasheet or some indication on the function of this 4-pin IC, which I removed from a McDonald's toy.  The IC is marked with 2MEE KRDB.

The disconnected pins (1 and 4) are V+ and GND respectively and was running on 3V.

The IC is attached to a speaker and a smaller coil (see below).  When the toy is bumped, a coil vibrates near the speaker magnet, producing a current to switch-on the IC.  Some music then plays through the speaker (though I can't get this to work reliably anymore after removing it from the toy).  Each end of the coil are attached respectively to pins 2 and 3 of the IC.

I was hoping to see if the IC is programmable -- would be a nice gadget to have!


texts: Why do computer circuits tend to have so many resistors and capacitors?

texts: As someone who has a decent understanding of computer architecture (but not of electrical engineering) I've always wondered why computer circuits tend to have so many resistors, capacitors, and other small circuit elements. Computing logic is binary - either wires have electricity going through them or they don't. So why the need to store/reduce the flow of electrons in so many different places? I'm guessing it has something to do with delivering voltage to different circuit elements from the power supply, or maybe controlling the rapid oscillation of the CPU clock, but I'm not sure.


texts:
I'm currently working on a audio project where I need to play a 16 bit depth signal with a speaker.
Right now I'm using an atmega328 for prototyping, two 8 bit shift registers (controlled by the MCU) and an R-2R DAC (and an LM386).
Given that the setup is not so simple, I was wondering if an MCU with a 16 bit DAC exists. Searching on Google, 12 bit is the maximum DAC resolution that I can find for an MCU so far.
So my question is: does such a device exist? Or is there a simpler alternative?
Thanks


texts: Why does equal resistance and capacitive reactance lead to 70,7% of the output signal?

texts:
I think I'm somewhere half way through to understand it.

Considering an ordinary voltage divider like this:

the output voltage is independent of the frequency and is equal to the ratio of these two resistors.

Going through to passive filters there is somehow an analogy, which is a bit misleading.

I know that the capacitive reactance depends on the frequency according to the equation:

$$X_C = \frac{1}{2\pi fC} [\Omega]$$

So following the idea of the voltage divider, I would expect the output voltage to be at 50% of the input voltage, but it is not the case. For some reason you have to use the impedance like:

$$V_{out} = V_{in} \frac{X_C}{\sqrt{R^2 + X_C^2}} = V_{in}\frac{X_C}{Z}$$

and it leads to the output voltage of 70,7%, when the resistance and the capacitive reactance are equal.

What have I missed?


texts:
I have a desk lamp that doesn't have a switch because it was custom made, and I discovered that it is bright enough to light the whole room. I figured I'd solve the switch problem by designing a circuit that would allow me to turn it on and off, and I'd like to do that from two locations: my bedside table and my desk (my room is very small). I'd position the circuit somewhere along the power cable, and my power board has a spare built in USB port so I figured it'd make sense to power a relay from that. Also the lamp is a 7.5W 240VAC globe. The circuit I came up with is as follows:

simulate this circuit – Schematic created using CircuitLab

Because I'm a still a novice electrical engineer, I have a few technical questions:

Does it matter which AC wire I put the relay on? Say could I just pick any wire and put the circuit in the middle of that?
What am I looking for in a relay that could pull this job off? Suggestions welcome :)
From my very basic knowledge of electronics, I know you can't just put a solenoid in a circuit with out something to take the load - hence the existence of R1. What would be a good value for R1? My guess is if it's too low, the relay would get hot, and if it's too high, the relay wouldn't work.

If you see issues with this circuit or have better design ideas, be sure to leave a comment. Thanks for your help!


texts: How do I increase the signal to noise ratio in a true condenser microphone?

texts:
I made a simple condenser mic as a test project for something more functional. However, when I connect my microphone I only hear the mains hum. Using a factory-made condenser I hear the mains hum except I am also getting a decent signal. I know for a fact then that my laptop has some grounding issues (the metal case always shocks me). I want to know why my circuit does not provide any audio signal what so ever. Go easy on me please, I know my way around audio equipment, but building it is a totally new field for me. Here is the schematic (adapted from John Salmon's version on YouTube):

Note: The Al foil is conductive as well as the back plate. The capacitor, resistor and power supply are functional.


texts: To ground capacitance of a power line modelling

texts: Is it correct to model to ground capacitance of an overhead power line as ideal current source when using matrix methods for load flow calculation?


texts: Simple AVR LED blink in assembly - why does this code not work?

texts:
I've been trying to blink an LED with AVR assembly. I'm using an ATMega168 chip and avr-gcc toolchain. Here's my code:

.include "m168.h"

.global main

main:
    ldi r16, 0b00000001
    out DDRB,r16            ; Set PB0 to output
    out PORTB,r16           ; Set PB0 high
    ldi r16, 0b00000101
    out TCCR0B,r16          ; Set prescaler to 1024
loop:
    in r17, TCNT0           ; If the counter is >= 128,
    cpi r17, 128            ; branch to dim
    brge dim                ; otherwise continue to light
light:
    sbi PORTB, 0
    rjmp loop
dim:
    cbi PORTB,0
    rjmp loop

I figure that my LED should be on ~50% of the time (values 0-127) and off 50% of the time (values 128-255). But it doesn't light at all (visibly).

If I run the program though my head it goes like this.

Counter TCNT0 starts at zero
LED is on
loop runs through without branching to dim
light jumps back to loop

Steps 3 and 4 happen in a loop for all vales of TCNT0 where 0 <= TCNT0 <= 127, meaning the light is on all this time

TCCR0B reaches 128, so branches to dim
dim jumps back to loop

Steps 5 and 5 happen in a loop for all vales of TCNT0 where 128 <= TCNT0 <= 255, meaning the light is off all this time

Eventually TCNT0 overflows, and we go back to the LED being on again. And so on...

Assuming my clock speed is 8Mhz (don't know how to find this in the datasheet), the timer increments once every 1024 clock cycles or roughly 4ms (10248 (1/8^6)). Which means my LED should be on for 512ms (128 * 4) and then off for 512ms.

Clearly I'm getting something wrong here or logic above isn't sound but I'm not sure where.

Edit:

If I set the comparison to compare with 255, it does blink. This confuses me even more!


texts:
In my project I want to use two power supplies of the type HLG-600H-24 with a power of 600W each and a efficiency of 95%. In the installation manual it tells me that each power supply should be at least 10-15 cm away from the next heat-generating source. Unfortunately I do not have enough space for that, the maximum distance is 3 cm. Now I assumed that with a heat power of 30W each this distance should not be a problem if I add flowing air to the setup (in between the power supplies. Is it possible to place them nearer to each other in this case, or should I still rely on the installation manual?
Data Sheet: http://www.meanwell.com/search/HLG-600H/HLG-600H-spec.pdf
Installation manual: http://www.meanwell.com/webnet/search/doc/DE/LED.pdf


texts: Converting 100MHz clock to 65MHz clock for VGA

texts:
I've written some HDL code to convert the frequency of the clock on FPGA (100MHz) to a freqency which is compatible with my VGA monitor (65MHz):

reg FLAG = 0;
reg [26:0]count;
always@(posedge clock)
begin
    if(reset)
    count <= 'd0;

    else if(count==65000000)
    begin
        FLAG = 1;
        count <= 'd0;
    end
    else
    begin
        count <= count+1;
        FLAG=0;
    end
end

The value of flag would keep changing from 0 to 1 with frquency of 65MHz, but that isin't apparenly working for me. Can someone point out the error here?
Also, is there a better way to convert one clock frequency to another?


texts: How standard relays mitigate the problem of electrical arc?

texts:
I disassembled (tore apart?) an old 812H-1C-C relay to see what's inside, and found an expected piece of metal which moves between two other pieces of metal when activated by an electromagnet.

I was however surprised that there is nothing special to prevent arcing, and the contacts were rather small, compared to the contacts of a 10A 250VAC wall socket, for instance. Despite the fact that the relay was used a lot, there was no traces of contact wear.

What's the trick? Why arcing is such an issue with wall sockets or any other connector, but is not an issue inside a relay rated 16A 277VAC? Is it because the relay is sealed, and filled with non-conductive gas which somehow prevents an electrical arc?


texts:
I am trying to get the right pinout to this module from a Canon MX492. I would like to know which one is goes to red, black, green and white for a usb connector. I don't have the whole printer to test what goes where and I'm fairly new to the whole hardware hacking thing. This has eight pins on a ribbon cable. I would like to use it for a RPi. All I know is it is possibly a USB module.

Edit:

Edit: Chip markings.
Marvell

88W8782U-NAP2
P14V750A2JW
1436 B0P
TV C005


texts: Unable to get bootloader working on custom PCB with AT32UC3L

texts:
I have designed a PCB for a client recently, everything is fine with the hardware and software (application is working as it is supposed to). Now we are facing the need to update the program inside the microcontroller, but since these PCBs are installed at different places over the world, it would be perfect to install a bootloader and use the same UART as used by the application.

Board description

AT32UC3L032
One UART already used to communicate between board and PC
Couple of I/Os for the application
Couple of state LEDs

Relevant PINS and config

PA01 # Used for entering ISP with high level

PA20 # Used for application and ISP UART
PA21 # Used for application and ISP UART

#define COM_USART               (&AVR32_USART2)
#define COM_USART_RX_PIN        AVR32_USART2_RXD_0_0_PIN
#define COM_USART_RX_FUNCTION   AVR32_USART2_RXD_0_0_FUNCTION
#define COM_USART_TX_PIN        AVR32_USART2_TXD_0_0_PIN
#define COM_USART_TX_FUNCTION   AVR32_USART2_TXD_0_0_FUNCTION
#define COM_USART_IRQ           AVR32_USART2_IRQ
#define COM_USART_BAUDRATE      115200

Tools used

Windows XP
Atmel Studio 6.1
AVRONE programmer

After many hours searching, I've found the Atmel Software Framework DFU, provided in ASF 3.14.0.834. That was looking promising, I was able to install it on my board using provided tools :

AVR32Studio 2.6.0
program_at32uc3l-uart-isp-1.0.1.cmd (provided script with ASF)
Flip 3.4.7 (batchisp)

At first, I used .bin and .dat provided with ASF, installed using the script. Now trying to upload application using batchisp command :

batchisp.exe -device at32uc3l032 -hardware RS232 -port COM1 -baudrate 115200 -operation erase f memory flash blankcheck loadbuffer myapp.hex program verify

But always getting :

Device selection.................... PASS
Hardware selection.................. PASS
Opening port........................ PASS
Synchronzing target................. FAIL    Timeout error.

I've tested with oscilloscope RX and TX from UART, data is going to board but PC is receiving a 27kHz square wave (can't be data from UART since there is no stop bit or anything, also frequency is probably not the same for 115200bps).

After more research, I've configured Word1 and Word2 in file at32uc3l-uart-isp_cfg-1.0.1.dat to get these values :

Word1 : 0xE11E0024
Word2 : 0x494F81AA

To use pin PA01 as option to enter in the ISP.

Also, loaded the source of the DFU in Atmel Studio 6.1 and noticed they were not using same serial port configuration, so changed for the same as my application. Also added some LEDs toggle inside the main of the DFU.

After updating the bootloader in the board, no LEDs changes, same timeout, same square wave.

Am I missing something?

Bootloader.map
program_at32uc3l-uart-isp-1.0.1.cmd


texts: How to prevent a low duty cycle load from flickering lights

texts:
This is a follow up question to this:

Alternatives to Large Transformer or PSU for Driving DC Heater

I've hooked up 120v AC to a zero crossing SSR and a 3.2 ohm resistive load. To get my desired wattage I send trigger pulses the the SSR periodically to create a 10% duty cycle.

This is working fine, but as I expected it's causing the lights in my workshop to flicker.

What's the simplest way to prevent this? I would like to use as few "large" components as possible.

Here're my ideas:

Use an inductor to limit the peak current to a more reasonable level.
Rectify the AC, then feed that into a large 200v cap. Then Draw from that using a DC SSR.

Update:

I've switched to a 1000W electric cooktop with a much more reasonable peak current. This also flickers the lights every time it switches on and off, although that's once per 5 seconds now instead of 4 times per second. I guess Spehro was right I just need better lights...


texts: Digital bathroom scale circuit - how it works?

texts:
I'd like to understand how the digital bathroom scales work. I was able to gather that there are four three-wire load cells connected into the Wheatstone bridge as suggested below. The load cells have three wires which seem to be connected as if there were two resistors (R1A,R1B first cell; R2A,R2B second cell, etc). The resistance of the four load cells is approximately the same, about 1kΩ, and changes slightly under pressure. (Both resistances RA and RB change.) The PCB carries the symbols E+/-, S+/-, which most likely stand for 'excitation' (input voltage) and 'sense' (output voltage).

Can someone explain how this thing works? I understand that the Wheatstone bridge acts as a voltage divider and that the voltage difference is measured between S+ and S-. However, I do not see how can it work with the four load cells connected in this way: if I position myself on the scale perfectly so that the pressure is identical for all load cells, the voltage difference wouldn't change. If the pressure is not the same, then the voltage difference is going to be random. Any ideas?? I suspect that the load cells may be more intricate than I think. Or could it be something else?

Edit: Added a photo of the PCB.

simulate this circuit – Schematic created using CircuitLab


texts: Combining inverting and non inverting opamps

texts:
I have a circuit:

Assuming the op-amps are ideal, how do I derive an expression of Vout in terms of A and B?
I set B to 0 and worked out that the output of the opamp connected to A is 9A, and by setting A to 0, I worked out the output of the opamp connected to B is -2B.
I then merged the two expressions together, forming Vout = 9A-2B. I think this is incorrect. Please help me understand where I went wrong.


texts:
I've been reading about how energy is actually transported in circuits (I first read about it here: http://amasci.com/miscon/ener1.html). The description in this article of why electrons don't move around the circuit carrying energy like buckets, picking up energy from the battery and dumping it at the load, is reasonable to me, some points in particular being that electron drift velocity in circuits is actually very low and that in AC circuits electrons don't even drift along the entire length of the circuit but rather oscillate, so they don't even travel from sources to loads and back. Instead, it's electromagnetic waves that carry energy through a circuit.

I can accept this but now I'm confused about how you would interpret calculations of energy transfer in terms of electrons, calculations which also seem reasonable to me but seem to contradict the arguments above.

For example, suppose you have a 9 volt battery and you want to increase its energy by 500 J. Since a volt is J/C, \$ \Delta E = V \Delta C \rightarrow \Delta C = \frac{\Delta E}{V} \rightarrow \Delta C = \frac{500 J}{9 J/C} \approx 55.56\ Coul\$. Converting this into electrons, this is about \$ 3.47*10^{20}\$ electrons.  This seems to suggest that you would physically need this number of electrons to pass between the terminals of the battery to transfer this energy. Is this calculation invalid? If not, how do you interpret this calculation in terms of electromagnetic waves?


texts:
I have this problem 3.32 from Fundamentals of Electric Circuits 6th edition by Alenxander and Sadiku. I have drawn the circuit in LTspice. My goal is to solve this problem using nodal analysis and supernodes. I am not sure how to handle have two supernodes in series, can someone give me a suggestion?

This problem is for an intro to circuits class. Its asking me to identify the voltages at N1, N2, and N3. In this section, we were dealing with super nodes. From the supernode definition I know that a supernode is when a voltage source is connected between two nonreference nodes. Notice, and the part that is confusing me is that between N1 and N2 there is a supernode, and there also is one between N2 and N3. This problem is very easy as I know the solution doesn't even yield a KCL equation. I don't understand how the supernodes are working in this problem. I am really thankful for all the quick responses, hopefully that clarified what's going on in my head.


texts: Incorrect Manchester encoding from PIC microcontroller

texts:
I have written a C program for the PIC18F4620. My PIC works as an encoder, which encodes a data stream in Manchester code. My output is rd7, where it should appear the Manchester code, but only appears 0 to 1 transitions. Can anybody help me? Here is my code:

#define MAX_BITS 12
#define MANCHESTER_BIT 1

sbit ENCODER_OUT at RD7_bit;

sbit DATA_OUT at RD6_bit;

sbit LED1 at RD0_bit;
sbit LED2 at RD1_bit;

unsigned int Encode_val;
unsigned char Encode_State;

unsigned int Encode_Count;

const unsigned char START_SYNCH = 0;
const unsigned char SYNCH = 0;
const unsigned char END_SYNCH = 0;
const unsigned char SETUP = 0 ;
const unsigned char TRANSITION = 0  ;
const unsigned char COMPLETE = 0 ;
const unsigned char IDLE = 0;
void Start_Transmission(unsigned int ) ;

void InitTimer0(){
  T0CON         = 0x88;
  TMR0H         = 0xFE;
  TMR0L         = 0x0C;
  GIE_bit         = 1;
  TMR0IE_bit         = 1;
  TMR0IF_bit = 0;
}

void InitTimer1()
{
  T1CON  = 0x01;
  TMR1IF_bit     = 0;
  TMR1H  = 0xFF;
  TMR1L  = 0x06;
  TMR1IE_bit     = 1;
  INTCON     = 0xC0;
}

void Interrupt(){

  if (TMR1IF_bit)
  {
      TMR1IF_bit = 0;
      TMR1H  = 0xFF;
      TMR1L  = 0x06;
      DATA_OUT = ~DATA_OUT;

  }

  if (TMR0IF_bit){
    TMR0IF_bit = 0;
    TMR0H      = 0xFE;    //5 Khz interrupts   0.2 ms
    TMR0L      = 0x0C;
    LED2 = ~LED2;

 switch(Encode_State){

        case START_SYNCH:
            ENCODER_OUT ^= MANCHESTER_BIT; //bring line low, start synch pulse
            Encode_State = SYNCH;
            break;
        case SYNCH:
            Encode_State = END_SYNCH; // synch pulse needs to be twice the interrupt rate
            break;
        case END_SYNCH:
            ENCODER_OUT |= MANCHESTER_BIT; //bring the line high, end synch pulse
            Encode_Count =0;
            Encode_State = SETUP;
            break;
        case SETUP:
            if((Encode_val & 0x01))
                ENCODER_OUT = ((Encode_val & 0x01) | (ENCODER_OUT & MANCHESTER_BIT)); //next bit to transmit "1"
            else
                ENCODER_OUT = ((Encode_val & 0x01) & (ENCODER_OUT & MANCHESTER_BIT)); //next bit to transmit "0"
            Encode_State = TRANSITION;
            break;
        case TRANSITION:
            ENCODER_OUT = (Encode_val & 0x01) ^ MANCHESTER_BIT; //set the line for transition
            if(Encode_Count++ < MAX_BITS){
                Encode_val = (Encode_val >> 1);
                Encode_State = SETUP;
            }
            else
                Encode_State = COMPLETE;
            break;
        case COMPLETE:
            ENCODER_OUT |= MANCHESTER_BIT; //transition done, bring the line high
            Encode_state = IDLE;
        case IDLE:
        default:
            break;
 }
 }
}

void Start_Transmission(unsigned int val)
{
   int i, parity_bit_count =0;

    for(i=0; i < MAX_BITS; i++)
        if(((val >> i) & 0x0001) == 1)
            parity_bit_count++;

    if((parity_bit_count & 0x0001) == 1)
        val |= 0x8000;

    Encode_val = val;
    Encode_State = START_SYNCH;
}

void main() {
  TRISD = 0;
  PORTD = 0;
  LED1 = 1;

  Start_Transmission(0);
  InitTimer0();
  InitTimer1();
}


texts: How can I find the short circuit current across a and b?

texts:
In order to find R thevenin, I need to find Isc across a and b since there's a dependent source.
Based on my calculations, Vth=500/3V.
I've spent countless hours thinking about Isc,please help.


texts:
First off - I'm fairly new to electronics
I've been probing an AT45DB041B on a mobile printer board using my CH341A
The voltages on the printer board for the AT45DB041B pins are 3v
I just discovered that the CH341A is outputting 5v (Supposedly there's a fix for this)
Is there a chance I might have damaged the AT45DB041B or other components on the printer board?
Cheers
Edit: Not this exact model but some other knockoff (probably)
https://www.amazon.ca/Programmer-CH341A-Burner-EEPROM-Writer/dp/B01D4CXYJE
Edit2: I was using it to try to red data from MOSI/MISO. The CH341A outputs 5v on VCC/MISO/MOSI instead of 3v


texts:
I designed a circuit around LTC4366 as per the picture below. However numerous MOSFETs have been damaged and become useless.

Mosfets used : STH12N120K5-2; IXFT50N85XVH; STW13NK100Z - All are rated to above 800V and 12A

The Load is operated with 380VDC and can handle 450VDC MAX (the threshold in the circuit is set to 420VDC). The power supply can deliver 800VDC if it fails (and this is what I want to protect the load from)

1) If the Gate Cap (Cg) is 3.3nF the Vout never goes up. The circuit behaves as if it was in the protected mode.

2) If the Gate Cap (Cg) is 10pF the circuit works and turns off the MOSFET when the input voltage reaches approx. 420V. However if I set the power supply to 550VDC, the LTC4366 resets the failure every 9 seconds and after a few cycles the MOSFET simply dies and shows a short between Drain and Source


texts:
I'm looking for another solution to a problem.

I have 4 of the same infrared sensors which detect if an object is close or not (pretty simple). The difficult part now is that they don't have an integrated ID, so I can't see which of them is detecting something. I would like to use the least amount of wiring, for example an I2C solution.

Right now I'm using a kind of DIP-switch configuration (a connector in which the sensor cables are added and a simple wire bridge to create a ID) to set the sensor apart. Although this works, it requires a lot of cables.

I was thinking of an analog solution. Putting some resistors after the sensor all in parallel and checking the voltage. But I was hoping someone would know of a better solution.

The current sensor is a photoelectric sensor (BOS 5K-NS-RD11-02) from Balluff, but that's not the point. Maybe someone has a better option. I use CANopen, but I can also use something else like I2C.

I'm curious if anybody has used more of these simple sensors and managed to assign them a different ID or is there a photoelectric sensor that already has something where you can assign an ID to it?


texts: VHDL how to make a redundant case statement simpler?

texts:
I'm using case statements to check the bits of a word. Is there any way to write this more compact since it uses a lot of space (I have other signals on which I want to do this aswell).

...
case a(1 downto 0) is
        when "00" =>
            r(3 downto 0) <= "0000";
        when "01" =>
            r(3 downto 0) <= "0001";
        when "10" =>
            r(3 downto 0) <= "1100";
        when "11" =>
            r(3 downto 0) <= "1101";
        when others =>
            null;
    case a(3 downto 2) is
        when "00" =>
            r(7 downto 4) <= "0000";
        when "01" =>
            r(7 downto 4) <= "0001";
        when "10" =>
            r(7 downto 4) <= "1100";
        when "11" =>
            r(7 downto 4) <= "1101";
        when others =>
            null;
    case a(5 downto 4) is
        when "00" =>
            r(11 downto 8) <= "0000";
        when "01" =>
            r(11 downto 8) <= "0001";
        when "10" =>
            r(11 downto 8) <= "1100";
        when "11" =>
            r(11 downto 8) <= "1101";
        when others =>
            null;
    case a(7 downto 6) is
        when "00" =>
            r(15 downto 12) <= "0000";
        when "01" =>
            r(15 downto 12) <= "0001";
        when "10" =>
            r(15 downto 12) <= "1100";
        when "11" =>
            r(15 downto 12) <= "1101";
        when others =>
            null;
        ...


texts:
I'm making a buck converter with the following characteristics:

Input voltage: 24V

Output voltage: 5V-20V

Max current: 5A

*Constrains:
The transistor driver must be an IR2110

I have the following doubts:

Is it necessary connect and to control the high side and low side transistors even when I only need to use the high side one?

Can I check the output signal of the IR2110 before connect the transistor?

How is selected the value of the resistance RG?

Edit.

Vs and Vcc aren't connected, that was and error in the image.

I have the above circuit but with the transistor disconnected, and I'm testing the signal between pins 7 and 5 with a led, it does not turn on, but when I connect the led  between pin 7 and ground it does turn on. What could be the issue?

Edit 2:

I've simulated the circuit, but the result is not as expected.

The imput voltage is 20V and the duty cicle 50% so the output should be 20V, but instead I get a transient signal then just a 0V output.

For the IR2110 the green signal is the input, at pin 10, the blue one is the output at pin 7, and the red signal is the voltage at the load.


texts:
I have a question regarding the manual type relay switch shown in the picture.
I need relay with dual coil-latching, I thought of using avmomentary toggle SPDT to turn the relay on and off, but I will not know the position of the lever of the switch (whether it is set or reset.) If I use a relay with a built in manual switch which is on the top of the relay, is it possible to set and reset the relay using that without needing any external momentary switches? If I use the normal one then I would need an additional digital latch or flipflop.
Please let me know if I can the manual switch type relay and also let me know if there are any disadvantages with the manual type relay switch.
FYI: Relay -  ADJH23112


texts:
This question is related to Is it possible to “trace” a hall effect sensor on a PCB?.

As far as I understand it, a Hall effect sensor consists of a metal plate, plus a current source and an amplifier.

Instead of buying a Hall effect sensing chip, would it be possible to implement this with a PCB and a microcontroller?  A metal plate is easy to come by within a PCB, and current sources, amplifiers and ADCs are available in some microcontrollers (e.g. PSoC4)

Applications for this might include current sensing in a power supply, or position sensing of a magnet.

One drawback might be that the size of the plate would have a poor tolerance.  Are there any other reasons this wouldn't be possible?


texts: Zener Diode maximum current calculation based on max rated Power dissapation

texts:
Question as in picture part 3 a)

Do I calculate the maximum current based of the slope resistance of 1 ohm and Pmax 3W (I squared R)

Or do I calculate the the maximum current based on the 15V zener and Pmax 3W (VI)

Other examples in the course seem to point to using VI but if you apply Kirchoff's Voltage Law to the loop and include the slope resistance it obviously does not equate. On the other hand if you were to use (I squared R) to solve then the max current= 1.73A which seems excessive.

Can someone please help solve this problem?


texts:
I want to connect iM881A-M LoRa module to arduino.
And I want to ask which external parts I need to connect it.
In datasheet there are many parts that I think I don't need to use.
Please help me , I am only student.


texts:
So a NPN transistor has 3 legs. If you connect up leg 2 and take current away from it then current can cross over from leg 1 to 3. What I want is when you take away/give current to the central leg current cannot pass from 1 to 2 but can when no current is given/taken from the centre. Look at the schematic below to see what I would like to know exists.

simulate this circuit – Schematic created using CircuitLab


texts: How can I modify this circuit to if once the battery turned off, never turn on again or turn only when min. ~0.5V increased?

texts:
I made this circuit:

I would like the following:

The LM1 opamp wathching the battery voltage and the output high while the battery voltage higher than 3V. When the voltage drops below 3V, the opamp output go low and turn off the N-channel mosfet, so no more current consuption from the battery (except the watching circuit which is only 1-2mA).

How can I modify this circuit to if once the battery voltage dropped below 3V, never turn off, or turn on olny when the voltage higher than 3.5V?

Now my problem is when turning off because the low voltage, immediately turning on again because the voltage higher than 3.00V.


texts: What does a P-Channel MOSFET symbol with body connected to source mean?

texts:
I was just trying to source a power MOSFET, and I stumbled across a very odd symbol for a P-channel MOSFET.

I know that the arrow pointing out means it is P-channel, and I know that the dashed bar means it is enhancement mode. However, I have never seen a P-channel MOSFET that has the body terminal connected to source, every other symbol for them I have seen has body connected to drain.

My question is whether this difference in the symbol signifies that the component behaves differently than a standard P-channel MOSFET?

Thank you


texts: How to stream Arduino-based camera to HTTP server?

texts:
I'm designing a simple Arduino-based robot that would be capable of streaming an A/V feed (small color camera and microphone) over the Internet to a URL (my web server).

I would be using an Arduino board with either an Arduino WiFi or Ethernet shield.

Several problems:

How to send camera video feed and microphone audio feed to the shield (WiFi or Ethernet)?
How does the shield actually transmit the A/V feed? Does it automatically encode the stream or is this something I'd have to program myself?

Thanks in advance.


texts: ADC differential dynamic range vs Differential input voltage range

texts:
Is there a difference between Differential dynamic range(in volt) and the Differential input voltage range?
If I have an input that swings between 1V and 3.4V, Is the Differential input voltage range in the below( which is a screenshot form a datasheet) enough or not?


texts: What's the difference between chip families

texts:
I've been trying to follow Ben Eater's 8 bit computer design (https://eater.net/8bit) and I've manged to build something that broadly works but it's not very reliable. Sometimes modules don't work, if I reset the system and try again they might work. It's all very frustrating.
The main point where I've deviated from the original design is the choice of chips. In the original design, Ben used 74LS___ chips, but I had trouble getting hold of these, so instead I've used some 74HC___ chips.
I'm using a mixture of LS, HC and HTC.
Can somebody tell me what is the difference between

74ls___
74hc___
74hct___

I'm using a 5 volt bench power supply and lots of decoupling capacitors. I can see that all the chips are all getting about 5 volts. The clock is running at fractions of hertz through to 10's of hertz, so speed should not be a problem.


texts:
I asked Xilinx for such a list but they don't have a complete list. I wish to make sure all input files are in source control and all output files aren't. This is with 13.1-13.2 with ISE and PlanAhead

Some of the information they have provide is the list of PAR Output Files and the ISE Design Suite Files in the Command Line Tools User Guide, the source files list from here.

Edit Aug 19 2011: mentioned 13.2 and PlanAhead
Edit Sep 7 2011: removed EDK reference since some in answer


texts:
In working on a toaster project, We've started by tearing up an old toaster to recover the nichrome heating wire and mica sheets. But I'm uncertain how to re-create the wire joins.

In the original, metal plates are riveted to the nichrome wire to create a solderless join.

What alternatives are there to join heating wire in a foodsafe way, at the scale of a one-off?


texts: How can I control 8 LEDs using only 5 pins of a microcontroller?

texts:
How can I control 8 LEDs using only 5 pins of a microcontroller without using any shift registers or I/O expanders?
By "controlling" I mean turning an LED or a set of LEDs on or off, not just turning one only at a time like Charlieplexing.
Edited : This query  had a boundary of not using any devices or ICs other than the microcontroller, any possible number and combination of wires and resistors. Some answers tend to be useful for people who have the same question but using devices or ICs is allowed.


texts: how to use my smartphone as oscilloscope

texts:
i found this circuit that can make my laptop work as oscilloscope

can this circuit work with my android phone while am using this app

https://play.google.com/store/apps/details?id=com.nfx.noscpro


texts: LTSpice produces incorrect simulation for Class AB amplifier

texts:
I have been building a Class AB amplifier simulation using LTSpice.
While it simulates well for transient analysis (voltage gain of 0.9 at peak),
using ac analysis the the voltage gain drops to 0.268.

I also tried using zener diodes, and these do work well for ac analysis, however they are not common place in Class AB amps.

Can anyone explain what am I doing wrong?

Circuit

Transient Analysis

AC Analysis


texts: What is a good wiring configuration to minimize noise on an analog DC signal?

texts:
I am measuring a photodiode with a high precision ADC, but they are currently 0.5-1m apart. The voltage will be constant. I would like to take the measurements as quick as possible so it would be good to reduce noise rather rely on software to extract the value.

I have been looking into some of the different cables like twisted pair, coax or parallel, but they are targeted towards high frequency signals rather than DC.

Are there wiring configurations that would be good in this situation or would making a separate board for the ADC next to the photodiode be the better solution?


texts:
I have a question!.

As I understand,the 3 diodes are "more or less" the same but with really important differences:

Zener diode: Clamps voltage at a breakout lvl.
Schottky diode: Like Zener but it lose less voltage in forward mode and it switches way faster.
TVS-Diode: The transient voltage supressor is to improve between other applications the EMC (Characteristics against EMV noise).

Am I right?
The point of this question, is that as to test, I took a Schottky diode, where  the Breakout Voltage was 40V. I connected it directly to battery.
As i tested that with 24 V, a low current value was flowing (obviously).
But I expected that as any resistance was connected in between, it would burn out more or less when it triggers (ideally at 40V).

The source did not have a current consumption bigger than 40 - 50 mA.  After 40V, it should be like a 0 Ohm resistor, right? It worked like that until a value of 56V, where it directly exploded. How is that possible?

Thank you very much!.
Greetings.


texts: What does maximum frequency range really mean in an inductor?

texts:
I'm trying to decide whether or not to order several 0.22uH inductors from http://www.futurlec.com/Inductors.shtml for my radio application where the frequency is well over 100Mhz.

The website states: "Frequency Range Up to 1MHz"

How is this possible when an inductor is really wire wrapped around something? or does that refer to something else?


texts: I am using an LED in my project. I need to provide uniform intensity or uniform spread of light using this LED in a particular area(Small region). Please tell some techniques for this. I have read about the use of plain glass with some chemical coating and place in front of the LED. Anybody knows about these? Please help me to find an appropriate technique.


texts: solder/join single copper filament to contacts (speaker tweeter)

texts:
As a result of the careful shipping of UPS, my speakers arrived with broken tweeters. One tweeter in particular has had its connections severed when the plastic support broke. I need to re-connect the filaments.
In this picture the two single filaments coming out of the tweeter are visible.

Those filaments need to be connected back to the contacts' plate that broke off (the plastic plate itself has since been reattached with glue):

There is about 1 cm gap from when the filaments are broken to the metal connection on the plate.
I have been told that the filaments were covered in enamel, and to scrape it off with a scalpel. I tried, as best as I could; hopefully I managed to remove the enamel but I am not sure. The filaments are so small I am worried they would break if I scrape more.
I have a small soldering iron, like this: https://www.clasohlson.com/no/Cocraft-loddepenn-HS-30L/p/41-1364
What would be the best way to do this now:

Bridge the filaments to the metal connections using a filament from electrical wire
Bridge it by making a strip of soldering tin
other suggestions?

Thank you


texts: How to define n-bit signed int in systemverilog?

texts:
We can define unsigned integer like these:

typedef bit[4:0] int5; // 5 bits unsigned integer
typedef bit[3:0] int4; // 4 bits unsigned integer

How to define type for signed integer?

e.g. 6 bits signed integer range from -32 to +31

typedef bit[5:0] signed int6signed; // doesn't work


texts: Why does it take time for electronic scale to measure?

texts:
If I am standing on a digital scale or measuring the weight of my luggage,
the display doesn't show the weight immediately - it takes a few fractions of a second.
Why is that and can you overcome it to always, immediately show the current weight (e.g. weighing the exact weight of a continuously filling cup)?


texts: Low frequency low voltage Sine wave generator

texts: I want to build a low frequency (around 10 Hz) and low voltage (about 3V) sine wave generator to drive an electro magnet. It would be very helpful, if you can suggest few efficient ways of doing this.


texts: Why do some voltage reference ICs (LM385B) have 8 pin packages where 6 pins are NC?

texts: A search for voltage reference LM385B reveals that most of its many versions come in either 3-pin TO packages or 8-pin SOIC/TSSOP packages. Very few are 3-pin SOT-23 packages. I was wondering why is this? Why have 8 pin packages where 6 pins are NC?