texts: LED luminous intensity vs forward current and duty cycle

texts:
Could you please help me to understand more about below.

I am comparing two LEDs. One has 2330 mcd of luminous intensity and the second 1300 mcd. Both having 20mA of forward current.
My understanding is LED with 2330 mcd luminous intensity will output more light than 1300 mcd LED, is this correct?

I would also like to know, in datasheet it is mentioned that peak current of 100mA at duty cycle of 10% with frequency of 1kHz. Does this means, I can not drive with 10% at 1.1kHz and onwards, below 1kHz it will be fine to drive the LED.

If anyone have any related document link to understand, please share with me.


texts: What's the name of this type of connector

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What's the name of the connector in the picture below? Is it suitable to use such connector and wires as signal wires routed from main PCB to the front panel for ethernet and USB?

Update:

After some more searching on Google, I finally find the name and one vendor who make this type of connector, http://www.jst-mfg.com/product/pdf/eng/eXH.pdf. It's name is "2.5mm pitch/Disconnectable Crimp style connectors".

But I still want to get some information about using this type of connector with the standard USB/Ethernet cable to connect the main PCB and the standard USB/Ethernet connector mounted on front panel. Or there are other better choices?


texts:
I have bought enclosure for my power supply (datasheet), which looks like the follow:

How can i connect the plugs to my circiut? Soldering is not an option because the box is made from ABS.


texts: Can I connect Arduino ground to the negative terminal of a battery?

texts:
I wanted to use a transistor to switch a circuit that has its own power source (a battery).

It appears you could do something similar if you had two battery power sources, but in simulators, it doesn't seem to be the same for an Arduino connected to the USB port's ground.

This seems to work as best as I can tell.  The attempt is to simulate a battery powered Arduino switching the transistor with an output pin.

simulate this circuit – Schematic created using CircuitLab

This doesn't seem to work but I don't know why.  The intent is to simulate connecting the negative terminal of the battery to the Arduino ground.  In the simulator I have that shows current flow, this is a no-go.

simulate this circuit

Is this just generally a bad idea?  Should I use a relay instead?  Or an optocoupler?


texts: Finding the Current in a Series RLC Circuit

texts:
Question :

If the input to an RLC serise circuit is \$V=V_{in}\cos(wt)\$, what is the current I in the circuit in terms of \$V_{in}, w, t,R,L,C,\theta\$?

Answer :

$$I = \frac{V_{in}\cos(wt-\theta)}{\sqrt{R^2+(wL-1/wC)^2}}$$

My Steps :
\begin{align}
Z&=R+\frac{-j}{wC}+jwL\\
 &=\frac{RwC+j(w^2LC-1)}{wC}
\end{align}

If I sub the Z into \$I=\frac{V}{Z}\$ to gain \$Z^{-1}\$, the result seems wrong. How to obtain the answer?

Thank you for your help.


texts: Where are the external oscillator pins on PIC12LF1572

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I have searched the whole datasheet, but couldn't find where are the OSC1 and OSC2 pins are. I've found the CLKOUT (which is CMOS output) on RA4 and CLKIN (which is TTL input) on RA5. But I need the XTAL input/output pins.

I tried connecting my 4 MHz crystal to these CLKOUT & CLKIN with two 22 pF capacitors connected to GND, but it's not working.

I need to use UART on this microcontroller, that's why I need external crystal oscillators.

Please suggest some solution.


texts: How does carrier frequency and pulse width modulation in a VFD work together to control AC motor speed?

texts: There is a lot of online information about this but there is also a lot of contradictory information. What is carrier frequency exactly and does it stay the same or does it vary? I understand the concept of PWM but if carrier frequency stays constant, then how does an AC motor see varying degrees of pulse width in order to operate on a simulated AC signal? I'm just trying to find the truth, in detail, about the relationship between carrier frequency, the speed reference signal, and PWM in order to control an AC motor.


texts: Bitbang ATMega-328PU with CT210x using avrdude

texts:
I have made a breadboard-arduino with an ATMega-328PU and the standard components taking help from Building an Arduino on a Breadboard. I interfaced the CT2102 Breakout Board with this assembly:

DTR - SCK
RXI - MOSI
TXO - MISO
RTS - Pin 1 On the ATMega

Before everything else, I downloaded ans installed the CP210x Drivers from their website. Now, it does come up on the list of "Attached USB devices" in the terminal window through the command ls /dev/cu.* and ls /dev/tty.*

To check if everything's working correctly, I issued the "Read Fuses" command which:

avrdude -P /dev/cu.SLAB_USBtoUART -b 19200 -c avrisp -p m328p -v

I hit the reset switch on the breadboard: following what hoipolloi said on Arduino Sketch upload issue - avrdude: stk500_recv(): programmer is not responding.

No luck! avrdude failed saying:

avrdude: stk500_recv(): programmer is not responding

Can anyone please help?

I tried connecting it with cu command, it says connected. But when I try reading data off of it (fuses) with

avrdude: initialization failed.


texts: How can I reduce the heat on these pipe soldering pliers?

texts:
I'm trying to use these pipe soldering pliers https://www.garrettwade.com/copper-pipe-soldering-tool-gp.html to compress and heat the ends of nylon rope so that the ends are more finished and secure.

They currently heat up to around 900f. I need the heat to be around 400f. It would be really great if I could specify the temperature as you would with a good soldering iron, but I'm not sure how you'd do that.

The best idea I have is to reduce wattage with a simple in-line light switch or other similar dial.


texts:
I been trying to figure out this diagram, and Can't understand what happens from the beginning of the input , how the voltage changes in a way that "shuts off" one transistor. Also cant understand the direction in which it goes in the input signal .

Does the voltage goes off completely on one transistor at a time whle there is a signal ?

How does the signal works in the preamplifier transistor?

What path does the current takes when the signal changes in the input?

(A hobbyist about electricity , learned only the basics)


texts: Building a first State Machine circuit - Technical Help

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I just learned how to synthesize a diagram of a finite state machine into a diagram of a logical circuit composed of D flip flops, a clock and logical gates.

However, I don't really have much experience with an actual physical building of an electrical circuit, so I thought I might try.

I was thinking about trying to actually build an electrical circuit of the following state machine diagram:

In other words, the description of the circuit is:

The circuit will have a button to press down and 3 LEDS.

At each point in time, only one of the LEDS will be on.

If the button is not pressed, it will remain in it's current state. If the button is pressed, then the turned on LED will change cyclically between the 3 LEDS, at a frequency determined by the Clock component.

(Also, possibly, a reset button to bring the state machine to an initial state)

My question is this:
How would you technically do this? I have no acquaintance with the different brands and kinds of electrical components.

I know I need 2 D-flipflops because there are 3 states. I also know I need a clock to connect into the flipflops, and I would need OR/AND/NOT gates. I think I would also need a Mux to choose the specific LED to light according to the current state.

How do I find such suitable components to buy? I'm afraid I wouldn't know such a component if I saw one, the technical terms in some of the buying sites I visited kind of baffled me.
Could you suggest components for the gates, mux, flipflops and clock?

Any tips and advice regarding this first amateur try would be very much appreciated.


texts: Help a beginner who wants to start microcontroller coding

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I see lot of chip from Atmel company like AT89C2051,AT89S52,Atmega32,P89V51RD2.

Suppose I write a code for Atmega32 which blink one LED after 10 milliseconds.
Can I use the same code for  AT89C2051, AT89S52, P89V51RD2 if I change the port?

So if I buy one USB ISP programmer for Atmega32 MCU can I use it to program  AT89C2051, AT89S52 also? Or does anybody compare the chip in terms of compiler, programmer, coding language, development board etc.?


texts: what is field exitation type of 775 DC motor?

texts:
There are different types of field exitation modes. Some of them are

Shunt wound
series wound and
permanent type

So, what type of motor is 775 DC motor?
i have tried to search the type from different websites but found nothing which describes the type of motor
Motor DETAILS
DSD-775 HIGH POWER DC MOTOR
WEBSITE:  http://www.dsdmotor.com/ProductShow.asp?ID=271
PICS:

I also need to know the resistance value, the inductance value and the inertia of the motor?
THANKS IN ADVANCE!


texts: How to determine power from emitted light using a photodiode?

texts: I have a project that involves detecting blue light (400nm-490nm) from Cherenkov radiation to find the power that is being generated by the reactor. I understand the photodiode will give me a leakage current that varies directly with light intensity, but how do I calculate power? Does it involve using the input voltage from a battery that my photodiode will use? The resistance in the photodiode circuit?


texts:
I have a signal cable (also transmits power) that is extremely short (see attached picture).

I would like to extend the cable with one meter (3ft), and I was thinking of cutting it in two (again see picture), and then attaching it to either a phone cable or a flat console (serial) cable, but I don't know how to best attach the cables.

How do I attach thin twisted cables so that I can extend my signal cable?

Edit: I have tried different ways of extending and done extensive testing that the signal survives (it does).  However, none are good "permanent" solutions.  The signal is 9600 baud, and the device draws minimal amounts (<1W) of power.


texts:
Can you please give me a definition, or at least a more specific context, of the term "point-of-load" converter/regulator? I have seen around explanations on related products or applications but no real definition. Most important for me is, why do we need this extra term, instead of just saying DC-DC converter? Isn't that the same?

Thank you for your attention,
Leonidas


texts: Can a grounded thermocouple cause GFCI to trip?

texts: I noticed the tip of my soldering iron is case grounded. I understand the GFCI compares voltages and trips if there is a difference (in the millivolt range). If the thermocouple generates a small amount of voltage, can't it trip the GCFI? Moreover, what does the GFCI use as a voltage reference?


texts: Can I use a 0.7A charger in place of a 1A charger?

texts:
One problem that I usually come across is the current ratings on mobile phone chargers. Right now, I need a 1A charger (which was shipped with my phone) and I have a 0.7A charger handy. Both the chargers have a 5V output.

I read here Charging devices - Voltage and Amperage that:

  Correct voltage rating and too low current rating may cause damage.
  Slightly too low may be OK with computers an similar.

Now I am wondering:
1. What happens if I connect my phone to this charger ? Is it safe or will it cause problems later on?

Misc:
I have a 220V / 50Hz / Single Phase supply.
Phone: Samsung Galaxy S3 (if this is even relevant) and the charger I have is from Samsung Galaxy S3 Mini


texts:
simulate this circuit – Schematic created using CircuitLab

I have a DUT that can take packets from all 4 identical interfaces (A, B, C, D) Packets from one port can go to either one of the output ports (1,2,3,4). Example: Packets from A can go onto 1, 2, 3 or 4. Packets from port B can go to 1, 2, 3 or 4 and so on. Packets coming on the same port are in order but packets can be serviced in any order between A, B, C, D (no order is maintained since all 4 interfaces can be active at the same time sending packets).

How do I verify such a DUT? What scoreboard data structure to use?


texts: Do wifi cards on client devices adjust tx strength depending on signal?

texts:
In trying to answer a question about wifi optimization in homes, one has to know whether a slightly lower signal on a client device (due to low TX setting on a router, for example) would normally be compensated by an increased TX strength (such as seems to be the case with GSM devices) on the client.
If that is normally the case, then perhaps it's safer to bet on higher TX power settings on the routers, than on the client devices for battery and health-related reasons.
If, on the other hand, the bulk of client devices don't vary the TX power, then the best thing to do is to bring the TX power on the routers to a minimal level at which good speed is attainable.
Update:
this edit is to dispute the closing as off topic.
The question was flagged as a "question a about use of electronics device" which is entirely untrue. The question is rather about the way transmission-reception components are programmed normally in wifi enabled devices.
According to guide,

if your question generally covers ...

a specific electronics design problem

and is not about ...

consumer electronics such as media players, cell phones or smart phones, except when designing these products or modifying their electronics for other uses

I should add that the question applies to any device using wi-fi signal, be it a plug and play router for home use or a park-wide system of antennae. It's about how to properly configure TX and RX in terms of power.


texts: Troubleshooting Noise/Quirks in Audio Circuit

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I am working on a project that takes in a single line-level audio channel and outputs 2 balanced/unbalanced +/- outputs from that channel. I have read a number of the excellent published articles online on circuit topologies for balanced/unbalanced inputs/outputs and have been testing the circuit shown in the partial schematic attached. I have tested the output on both a decent quality sony boombox (unbalanced RCA inputs) and a high end QCS amplifier (balanced 1/4"), and have discovered a number of quirks I've been trying to troubleshoot.

1) When connecting to either the QCS or Sony, as long as the audio signal (-) output is at the same potential as GND in the schematic, everything works fine, the sound is top notch. When connecting the Sony with the audio signal (-) as shown in the schematic, I would expect noise since the output is not (probably) at same potential with the Sony signal GND ... this is exactly what I get (a high pitched buzz). However, I would expect that the QCS, having balanced inputs (active I assume) wouldn't care about the actual (-) potential (I measured around 1mV DC, 5mV ACrms). However I get the exact same result with both, a high pitched buzzing noise). Anyone know why that might be?

2) Turning on the project device results in a light pop heard from the speakers, presumably from the initial DC bias current flowing from the cap. Is there a way to reduce or eliminate this? Would a larger output resistor help? (I'd prefer to keep output impedance at 100Ohm if possible.)

3) Without power to my project device, the sound still comes through the opamp follower (via an audio transformer) and is output (albeit very distorted with no DC bias) to the speakers. I wasn't expecting sound output without opamp power ... is there a common/easy way to prevent this?

4) When the device is working unbalanced with excellent sound, it still does add a minimal amount to the noise floor (white noise/hiss). It's not really significant, but what is the best way to minimize this generally?

Thanks for any input.


texts: amplifying audio lm386 dumps negative part?

texts:
I am amplifying and audio signal with ac levels of around +-0.3V.
This signal also has DC level of 1.2V

I used 2 DC block capcitors because I saw the input should be ground referenced.
The output of this circuit that I measured was for some reason also DC bias [even though I used a dc block capcitor aswell] but the sound was awful and I think it is because the output has lost all its negetive sound .
Also first time I noticed this amp doesnt have -Vsupply but  ground.
I know it is also got truncate but I doubt thats the reason .

I know there is FFT on the right side but this is not FFT of the audio its in time plain .

I thought maybe to lose the DC blocks in the input and to put 1 or 2 diode in series to lower the DC but I dont think it will end up well.
Also thought to replace LM386 to LM370 but the input resistance is 2M .
any solutions How can I get the negative part ?


texts: Ground induced noise between two connected boards

texts:
I have a CNC system that consists of a CNC controller connected to a PC via USB. The controller is in turn connected to a stepper motor driver board. My problem is that some time the turning off/on of the stepper motor drive power supply induced larges spikes in the power distribution of the CNC controller, some times to the extent of resetting the system.

When the drives are switched on you can even see the 20khz PWM frequency of the drivers switching on/off on the CNC controllers power distribution as thin voltage spikes. If the drivers board is disconnected from the controller board there is no interference.

I am assuming that since both boards are connected with a common ground that this is the main cause of the induced spikes. Also the CNC to driver interface is via digital isolators, so in fact the CNC board and driver boards are electrically isolated.

I would like to know what I could do to minimize this problem. Any suggestions are greatly appreciated.

The controller uses the USB power supply and is isolated from the drivers. But only when the drivers are connected to the controller do I see noise being injected into the controles (usb powered) power supply.

A diagram to illustrate the architecture:


texts:
While I was reading the STM32 HAL drivers for timers I found this macro:

#define __HAL_TIM_DISABLE(__HANDLE__) \
                    do { \
                      if (((__HANDLE__)->Instance->CCER & TIM_CCER_CCxE_MASK) == 0U) \
                      { \
                        (__HANDLE__)->Instance->CR1 &= ~(TIM_CR1_CEN); \
                      } \
                    } while(0)

Since the while part is always wrong there should be basically no loop, and the do-while seems redundant to me. But since they distribute it in the HAL like this, I suppose there is some point? Can anyone point out which?


texts: Why unintended capacitances are an issue for the design of chips?

texts:
I understand as the clock frequency of a chip is increased, some issues arise. Probably, the most known issues are those related to the so-called "power wall", which alludes to the fact the thermal dissipation becomes an issue when the clock reaches a given threshold. However, there is something else I don't get: as the integration scale of the chip (i.e., its density) increases, distances between inner wires (tracks, actually) shortens, increasing capacitances and bounding the clock rate, right? But in which way capacitances inhibit higher frequencies?
To quote Stallings:

  The speed at which electrons can flow on a chip between transistors is limited by the resistance and capacitance of the metal wires connecting them; specifically, delay increases as the RC product increases. As components on the chip decrease in size, the wire interconnects become thinner, increasing resistance. Also, the wires are closer together, increasing capacitance.

Although I am not an engineer, I can tell why thinner conductors are bad for chips design. But I have no clue why high capacitances may be an issue. May any good Samaritan clarify that for me, please?


texts: Why is the base resistance suggested to be one-tenth of the emitter resistance times beta?

texts:
This is a follow up question from Emitter follower biasing with voltage divider or the emitter follower design example in The Art of Electronics.

Why is the recommended one-tenth ratio of base resistance to emitter resistance times \$\beta\$? The base current should just be approximated to the emitter current divided by \$\beta\$, with the base current changes against the varying \$\beta\$.


texts: How do I compute the lifetime of an electrolytic capacitor?

texts: I am considering using a KZE series (by United Chemi-Con) electrolytic capacitor, which has a specified lifespan of 5,000 hours at 105°C with rated ripple current. Now, for an example assume I am using it at room temperature (25°C) with half the rated ripple current and half the applied working voltage. How long would the capacitor last? In future, how would I calculate it?


texts: Normally Closed Negative Output, Positive Input Relay

texts:
I'm attempting to wire up my remote start in my manual transmission vehicle to ONLY start when the vehicle is in neutral. The way that the transmission works is like this:

When in neutral, resistance is >150 ohm and no voltage.
When in gear, resistance is <1 ohm and 12 volts.

However, the remote start neutral safety wire works like this:

Remote start will start if ground circuit is complete. ("Shows ground")
Remote start will NOT start if ground circuit is not complete.

My understanding is that I'd have to use a relay that accepts a positive input, and provides a negative output. I had wired up a 5-pin SPDT relay like this:

30 to ground out (remote start safety wire)
85 to positive input (transmission signal wire)
86 to constant ground (chassis)
87a to constant ground (chassis)

In theory I expected this to provide a normally-closed ground circuit to the remote start indicating that the car is in neutral and able to be started, and when the car is in-gear, it would provide the positive input signal to cause the relay to toggle 30 to 87 (not connected), thus opening the circuit and disabling remote start.

Unfortunately that did not work; the relay did not toggle at all. When I hooked up a multimeter to the positive input (with the ground connected to the chassis), it showed 0.45 volts, as if it were encountering resistance. Disconnecting the positive input from the relay caused the multimeter to read 12 volts again.

I've searched extensively online and there was one video that showed that the above connections should have been appropriate, but otherwise no other help to confirm that is the correct process.


texts:
There are tons of schematics and concepts online of AM or FM transmitters. I wish to build one using discrete components (at most an op-amp).

The problem is, how would transmission of stereo work? In my current circuit, I have two outputs from pre-amps for left and right channel. I want this to be transmitted and played back on a radio correctly.

Is this just a matter of transmitting left and right separately on two op-amps but on the same frequency? Would that work? Or would the signals likely cancel each other out?


texts:
I need to calculate baud rate of wireless sensor which operates on 433.92Mhz and uses OOK modulation.
Signal wave form and packet structure are known.
Packet = 36bit (44.7ms), each bit consists of 2 impulses with different duration  (bit 0 - LOW & 2HIGH, bit 1 - 2LOW & HIGH)

So the question is how to calculate baud rate for this sensor?


texts:
My first question on EE, please be kind. :-)

I am trying to learn how the ADC works on this Cypress PSoC 4100 board.

The circuit in the picture does nothing but power the board, connect it to the LCD display, and show the readings from the ADC.  The ADC is set up to use the internal 1.024V reference with the bypass cap, which is built onto the 4100 board itself. The input to the ADC is on pin 2.0, which is in the upper-right corner of the photo.

I noticed that the ADC never output the minimum value (which is -2048, since it's a 12-bit ADC and outputs signed values), even when I connected the ADC input to one of the ground rails. The only way I was able to get a minimum value is to connect the ADC input directly to the ground pin on the 4100 board.

Using my multimeter I discovered that there was 500-600 ohms of resistance between the breadboard ground rail and the ground pin of the 4100 board!  In the photo, the multimeter black wire (entering at the bottom) is connected not exactly to the 4100 board's ground but to the breadboard socket right next to it, while the red wire (also entering at the bottom) is connected to the ground rail on the lower breadboard. That is connected via a black wire on the right to the ground rail on the top breadboard, which his connected to the ground pin.

The multimeter shows 580 ohms of resistance even though it's nothing but metal between these two points. That's causing the ADC (fed via the second red wire right next to the multimeter red wire) to read 100 or so mV instead of the expected zero.

If I wiggle the black wire that connects the ground rails of the top and bottom breadboards, the resistance jumps around a lot, anywhere from 200 ohms to over 1K.

Moving the wires that connect the two breadboards to the left side and away from the LCD signal lines didn't change anything.

If I connect the multimeter red wire to the top breadboard's ground rail, right next to the black wire that connects it to the ground on the 4100 board, I still see about 230 ohms. This is over a distance of about 1cm!

Unplugging the LCD display reduces the the resistance to about 38 ohms.

Removing power by unplugging the USB cable (it's USB-powered so it's all 5 volts) reduces the resistance down to about 6 ohms.

When I tried measuring the resistance between two (connected) ground rails on another otherwise empty breadboard, I saw 3 ohms max.

My question is, what's causing this resistance and how do I get rid of it? Is it some kind of inductance issue? Having 100 mV or so of voltage on the ground rail isn't fatal to the project by itself, but whatever's affecting the ground rail might also affect the input to the ADC, which would throw off the readings.

Thanks!


texts:
In electronic books, the small signal model of a BJT is given as:

I've just studied two-port networks theory and, as an application, another book I'm reading shows this picture:

1st question: why do we have a voltage-controlled voltage generator on the left (which is absent in the first image)?

2nd question: why do we have a current-controlled current generator on the right? I've been always told that the BJT is a "transconductance amplifier" (= collector current is controlled by the base-emitter voltage, not by the base current, as shown indeed in the first image)

Thanks


texts: I want some 100 w bulbs in series to lit one after another on the same switch. How it can be done? Please suggest some methods


texts:
I'm trying to understand current mirror circuits and I've been reading this article. I'm unable to understand the input part of the circuit where the author says "Producing the opposite where the collector current controls the VBE is not possible in the conventional use of the device as a common emitter amplifier. The solution is to incorporate negative feedback." (refer to image).

I do not understand how the feedback is actually 'controlling' base to emitter voltage (Vbe).

From what I understand, the Base-Emitter junction is just like a diode with a fixed ~0.7V across it. So, no matter what current you give to the base through the feedback connection, won't Vbe be equal to ~0.7 volts? How are we actually controlling the output(Vbe) here?


texts: Can I use devices with different unit loads on the same bus? If not, why?

texts:
I've been having trouble getting a rs485 communications bus working with some external devices. I have an Arduino hooked up to a MAX487ECSA+ which goes through some cabling to my devices. Using an oscilloscope, I can see the signal (with sufficient amplitude)  reaches my devices but I get no response. The baud rate used is 19200.

I bought this breakout board from sparkfun to see if I could get some communication working. I hooked it up to my arduino and I get a response from my device.

The MAX487ECSA+ is a quarter unit load and the IC used by sparkfun is a one unit load. I'm unsure of the unit load of my devices. Could a difference in unit loads between the 2 ICs be the reason one circuit works and the other doesn't? If this is a reason, could you please explain why I can't use devices with different unit loads on the same bus?

EDIT
-A and B are correct, I have tried both ways


texts: Voltage across inductor immediately after the switch is closed

texts:
The contact switch in this circuit has been open for a very long time. The switch is connected to the circuit at time t=0.

What is the voltage across the inductor (VL) immediately after the switch is closed?

The answer to this question is 3 V, but why isn't it VL = 5 V?

I thought the inductor would have the voltage source as it's own voltage immediately after it is connected to the voltage source?


texts: I've seen rotary encoders that you can get with and without detents (example). What are detents in the context of rotary encoders? When would you want / need your encoder to include this feature in a design?


texts: One voltage reference per DAC or one voltage reference for all DACs?

texts: I have a circuit that requires six 18-bit DACs (AD5680) on it. Each DAC draws ~800µA at the high voltage output +5V and ~400µA at 0V output. Is there any issue with a single REF195 voltage reference for all of the DACs? The AD5680 is rated to supply 30mA. It can be assumed that the DACs are "close enough" to the voltage reference to not be an issue. The DAC output can be considered static, the output will change but not dynamically and there is plenty of settling time. I'm concerned with noise on the voltage reference supply bus or power supply pull or some effect that I have not considered.


texts: Digitally programmable switching regulator design

texts:
I need to generate a voltage switchable between two levels (5V and 10V) by a microcontroller running at 3.3V. It will be powering lamps at about 1A, low noise is not a major issue.

I have designed the following circuit:

For 5V/10V output R1=420R, Rx=580R, R2=3k

The black part is from the LM2596 datasheet, the red part is my addition to allow the voltage to be switchable. The MOSFET essentially allows the resistor Rx to be bypassed. The datasheet says R1 should be between 240R and 1.5k so there is room to adjust it.

The other option is to have the extra resistor to ground, like this:

For 5V/10V output R1=1k, Rx=750R, R2=3k
With the MOSFET on R1/Rx in parallel is 430R equivellent

This seems to be the more popular way of doing it. Is there any advantage to either method?


texts: Altium: Remove Small Sliver Openings in Hatched Pour

texts:
One of Altium's polygon pour modes is a hatched version, which allows the user to specify an individual track width and a grid size and it automatically generates a pour in a cross-hatch pattern. It also generates solid borders around component pads and traces. The benefit of using a hatched pour is that on larger boards it acts less like a heatsink (even if there are thermal reliefs on the pads it can still cause problems if the copper pour is solid) and promotes better solid joints. The problem is that sometimes this method leads to very small (<3 mil) openings in the hatch, as seen here:

These can pose problems during manufacturing as each opening in the copper represents a section of mask stuck to the core prior to etching. These smaller pieces can flake off in the etching solution and redeposit elsewhere on the board, causing copper that should be etched away to remain. This can lead to shorts between nets.

There can be thousands of these tiny sections on any given board so manually going through and filling them in is time-consuming and impractical.

How could this issue be addressed in Altium Designer 17? Is there a script that I can use to fill in these small areas to improve manufacturability of my board while maintaining solderability?


texts: Why are only 3 pins connected on a dual gang pot?

texts: First post on this platform... I am wondering if anyone knows why in some DJ Mixers (e.g. Pioneer) which use dual gang pots for channel faders, only 3 of the 6 available pins are connected. Also, looking at the schematics it looks like one of the 2 resistor elements of the pot is not even connected. Hence my question would be why not use a single gang pot in this case?


texts: What is the difference between DCM and PLL in e.g. Xilinx FPGA?

texts:
Some FPGAs have both DCM (Digital Clock Manager) and PLL (Phase Lock Loop) for use in internal clock generation.

Xilinx Spartan-6 FPGA Clocking Resources UG382 (v1.10) documentation describes a number of features for DCM:

Eliminate clock skew
Phase shift a clock signal
Multiply or divide an incoming clock frequency or synthesize a completely new
Condition a clock, ensuring a clean output clock with a 50% duty cycle
Mirror, forward, or rebuffer a clock signal
Clock input jitter filtering
Free-running oscillator
Spread-spectrum clock generation

However, to my understanding all these (or at least the majority, maybe not the "Free-running oscillator") are also available when using a PLL.

So, what is the difference in using a DCM vs. a PLL in an FPGA design?


texts:
I'm thinking about this part of this board :

As you can see, there is a resistor in the red rectangle (R26). my question is what is the usage of this resistor?

Well being a resistor for D14(CANRX) is acceptable (because the supply of the MCP2551 is +5V but the STM32F103RBT6 is 3.3V (logic level)) but for D24(CANTX) it doesn't make sense to me.

Note that I have used this circuit for my CAN bus without R26 and R27 resistors and it works very fine.


texts:
Are heatshrink tubings toxic for human health (e.g, using them in a "prolongedly-touched" place)?

E.g. if I use them for supporting the tip of my phone charger or the tip of a 3.5 mm Audio jack (for strengthening purposes), will there be any long term health hazards (toxicity etc.)? I am worried because I touch those places many times over the course of daily activities.


texts: How to make arduino GPIO to operate at 3.3v instead of default 5v

texts:
I am working on a project, I use arduino mega 2560 with system operating voltage of 5v, at the same time I have a Bluetooth module which operates at 3.3v is there any way to reduce my arduino output voltage without any external component such as resistor, ic etc
I saw the following statement in arduino website but couldn't understand,
"IOREF. This pin on the Arduino board provides the voltage reference with which the microcontroller operates. A properly configured shield can
read the IOREF pin voltage and select the appropriate power source or enable voltage translators on the outputs for working with the 5V or
3.3V."


texts: What do the boundary modules do in an IC?

texts: I cannot understand what is the purpose of digital and analog boundary modules embedded in an IC for testing. What are their function?


texts: How to reverse the pinout of connector in Eagle

texts: I have a screw connector with multiple pins and it seems like it will be easier to do the layout if I reverse the pinout on the connector. So if I have a 3 pin screw connector I would just need to switch pin 1 with pin 3 in the layout.  Is there a way to do that? Or do I just need to update my schematic to do it the other way?


texts: In the following question I couldn't find a way how to find the voltage Vc at time T+.Can you explain to me? How can I find impulsive current due to switch.I don't want complete answer to this question.I found T- as shown .


texts: How to mitigate voltage spikes when turning car ON?

texts:
I need to connect some things (LEDs and other misc.) to the 12V rail in a car. I understand that this rail gets a beefy ~100V spike on ignition. I have also heard that the battery soaks this spike (like a big capacitor). In any case, should I add circuitry to prevent the spike from hitting my LEDs?

Let me know if you need clarification. Thanks in advance.

Edit:
I am also interested in keeping MOSFETs and microcontrollers safe. Would hiding it behind an LM7812/LM317 offer protection?


texts: lock output solar panel if too few current

texts:
I use a solar panel which provide 12v-3W. I convert that to 5V using this converter.

This 5V is used as input of a card which to charge a lipo battery and as a power supply for a raspberry zero.

The problem when the power of the panel is under the nominal power of the raspberry Pi. The lipo chager don't work properly.

So my question : how to cut power line from solar panel if current is under                                      400mA ? Ref of a module or CI which do that?


texts: What is Normalized DC Current Gain (as oppossed to DC Current gain)?

texts:
I have a table that presents DC Current Gain for BC548B transistor:

and a graph that presents Normalized DC Current Gain:

Are those two things related? What does "normalized" mean? Why is the Y-axis labeled with numbers from 0.2 to 2 instead of something around 110 to 450?

My reason for asking this question is that I need to know the DC Current Gain for this transistor at Ic=2.0mA and Vce=5V, and whether it would be significantly different at Ic=2.0mA and Vce=0.5V-1.2V.

The table and the graph come from the datasheet for an On Semiconductor BC54X transistor: http://www.onsemi.com/pub_link/Collateral/BC546-D.PDF


texts:
Need help. Is it possible to wire 2 short led strips with 6 pin (ON-OFF-ON) SPDT switch in that way to have:
A) One led strip - ON, second - OFF;
B) Both strips  - ON;
Components: 6-PIN SPDT switch, 1 power supply, 2 led strips


texts: Replace Lithium Battery with Permanent Power Source

texts:
I have a currently dead Bluetooth speaker that had a Micro-USB port that fell off. The battery can no longer be charged and I'm not skilled enough with a soldering iron to re-solder the Micro-USB back on to the board.
However, I am capable of re-soldering the large battery leads with that of the positive and negative leads of a stripped power brick. Since the speaker doesn't move all that often in the first place, I figure this is an adequate solution.
I'm curious what kind of pitfalls I should avoid when doing this process. I have basic knowledge of electronic components, so I'm not so worried about that. I just want to clarify my assumptions before I go and set the board on fire.
Currently, the board is powered by a (dead) 3.7 V 300 mAh battery, as read off of the back of the battery. I want to replace this with a 3.7 V power supply.
However, I cannot seem to find one that matches these specs exactly. Since the power output is so small, and since it was a battery powered device, my assumption is the specs don't need to be exact. The board should have been designed with some redundancy in mind for voltage drops and such. Thus I was curious if a 3 V 1 A power brick would be sufficient to power this thing and not completely fry it.
Is my understanding of electronics right here or will I run the risk of breaking everything going this route?


texts:
I'm trying to develop a flow meter using the cross correlation algorithm.

I'm using 2x IR leds and 2x phototransistors and a MSP430F5529. One pair of phototransistor-Led go in the upper level and the other in  a lower level.

When the liquid passes in the first  pair of phototransistor - IR Led, the microcontroller reads the voltage from the phototransistor out, and after the liquid cross the other pair and the microcontroller reads the voltage again.

The signals collected are very similar but phase shifted as expected.

I analysed the data collected in Matlab software and used the cross correlation algorithm to calculate the phase shift between them, in windows of 250 points.

The results were very good, but sometimes the algorithm results in  values of zero phase shift. And analysing the plot, it can be seen, visually, that the 2 waves have a nonzero phase shift.

An example of a window is showed below.

For this 2 signals, the cross correlation results 0. But as can be seen, the 2 signals are phase shifted by about 13 points.

I know that the cross correlation algorithm will give me the delay of the maximum value of the multiplication of each point. But how I can calculate the phase shift between 2 signals like this example?


texts:
I made a schematic in KiCad with hierarchical layout. I'd like to check if the busses are connected the way I want. In this context I often read something about the netlist.
So my question is, how do I generate a netlist and what does it tell me about the connections?


texts: The "perfect" three terminal, 0.5A, voltage regulator

texts:
So I was looking at SMPS IC's the other day.  I needed a couple of low current bipolar power supplies.  I found these switch mode, three terminal voltage regulators.  Like the old linear 78xx series.  Here's the spec sheet of one, (CUI P7805-S) but there are a number of suppliers.  You can even hook 'em up backwards for a negative output voltage.  (though at reduced current and efficiency.)

I've order a few from digikey, but as I await their arrival I wonder if anyone has used any of these?  Are there any "gotcha's"?  (Besides the ripple and noise.)


texts:
I'm a navigation engineer, so I often have to deal with gyroscopes and their measurements. Out of curiosity, I've decided to build one myself and will give it a try with a Fiber Optics Gyroscope (FOG), which is a Sagnac Interferometer that consists of a laser, optical fiber coil, a beam splitter and a detector.

The basic idea is that the beam from the laser is split into two parts that enter the coil from the opposite sides. They travel through the coil until they meet and interfere in the splitter and then reach the detector. Since the interference ranges from destructive (zero output) to constructive (double the amplitude of a half beam), a large dynamic range detector is needed. Also, being able to sample it at least 10Hz (preferably even more) is desired.

I've looked into sensors like:

https://learn.adafruit.com/adafruit-tsl2591

which could be an easy option, since it does amplification and AD conversion internally. Just its max frequency is 10Hz, which is on the lower side of what I want. Also the sensor itself is very small, thus the alignment between the laser and the sensor could be problematic. Some laboratory sensors like this have much larger sensing diameters (5-7 mm), thus would like to find something bigger as well. The laser I am using has 635nm wavelength, thus silicon based sensors is not a problem.

So, I am seeking for an advice on what kind of sensor suits the most here for this type of application taking into account the high dynamic range, sensitivity and preferably linearity (although this will probably depend on the measurement circuit).

Thanks for help! (and sorry if smth is wrong - this is my first post :))


texts:
I designed the circuit and obtained the desired outputs correctly.
for for circuit it R = 1e3 , C= 0.15e-6, and f = 250 , ( for RC circuit) and in the second part it asks to increase the frequency to 2Kh that is R = 1e3 , C= 0.15e-6, and f = 2kh.
now it asks
Compare the gains and phases from question 1)d) and 1)e). Justify and explain
similarities and/or differences
I know the gain is Vout/Vin but the output looks pretty weird I have an idea but is there a difference between the two? I mean changing the frequency should change the gain or not?

here is output/input waveform for circuit with f=250H

and here is the one with f=2KH

I also plotted the bode diagram for both circuits. f=250, and f=2kh respectively.

here is the code for Bode digram ( frequency domain)


texts: General purpose diode between 2 power rails

texts:
I am looking at a schematic where there is a general purpose diode connected between the positive side of a 5V DC rail to the positive side of a 12 V DC rail.
The circuit is powered by a power supply that provides 12 & 5 V DC and these two input voltages are connected to a choke. The other side of the choke is where the diode connects the 5V to the 12V rail as seen in the picture.
What's the function of this diode?


texts: Does the expression of amplitude modulated suppressed carrier even exist in reality?

texts: I read that a negative frequency implies "forward" travelling wave and a positive frequency implies "backward" travelling wave, so.. does a  suppressed carrier amplitude modulated wave not exist due to destructive interference? As it has 2 exact frequencies but one in negative and one in positive.


texts: Does the positive and negative half cycle of an AC source sees different resistance?

texts:
In a source follower like this:
When AC source is at its positive half cycle, conventional current passes from base terminal to R_E and R_L and then straight to the ground. The resistance it sees is the input impedance Z_in.
But when AC source is at its negative half cycle, it passes from ground to R_E and R_L and then to the emitter terminal. Why does the resistance that this conventional current sees is still the input impedance Z_in and not the output impedance Z_out?
Zout is the resistance that the load R_L sees in its own perspective, that's why I though that if current passes from the ground to the R_E and R_L, it will also face the resistance of Z_out and not Z_in.


texts: Help understanding 2N3904 VCE breakdown voltage?

texts:
While I was designing a constant current source using a 2N3904 I noticed a behavior on the bjt that prompted me to look closer into it.

The issue is that although the datasheet specifies a minimum BVceo = 40V. Any voltage above 8VDC on the collector with base either floating or grounded (as shown on schematic) creates an sudden increase in collector current (suggesting breakdown) and the voltage across C-E is decreased as to limit power across C-E. I breadboarded the circuit below to investigate this.

My current mirror is to be used on the output stage of an audio headphone amplifier with Vcc = 12V. Any help understanding this would be greatly appreciated.

simulate this circuit – Schematic created using CircuitLab


texts: Why does the X-box 360 controller battery pack have an integrated breaker contact?

texts:
People owning an X-box 360 with wireless controllers came across a phenomenon where older controllers were switching off randomly while playing or if they were moved too quickly. Me and everyone I know always blamed the battery contact springs being too short. Everytime the controller switched off it was completely normal to remove the battery pack and pull on the springs so that they would be a little longer and would press more tightly on the battery contacts.
A few years have passed and my Xbox was sitting unused in a storage box, until yesterday when a friend and I decided to play Halo 3. We put new batteries in the controllers and noticed that they struggled to stay on for even a few seconds. After playing a few hours with my benchtop power supply soldered to the controllers' contacts, I started to investigate further into this issue and took the controller apparat:
To my surprise I quickly found that the contact springs weren't the culprits after all. What's causing the switch-offs was a contact in the battery pack itself, that only closes the connection between the batteries if the pack is inserted into the controller. This is done with a little notch on the controller's back that pushes two metal pieces that connect the two batteries and closes the circuit.
Over time these metal pieces corroded quite a bit and the springs of the battery packs loosened up which resulted in really bad to nearly nonexistent contact between the two batteries.

Why all of this?
This seems like a point of failure that could have been easily avoided.
The only thing I could imagine is to avoid short circuits if a battery pack is thrown into a bag. Because of the missing connection a short circuit would be nearly impossible. But then I wonder who would use a battery pack in a way like this as it's just a fancy AA cell holder. Why not just take some extra batteries with you as swapping them out takes only a few seconds longer than switching to a pre-equipped battery pack?
I don't even know if the battery packs were purchasable without a controller as I can see no use in having more battery packs than controllers.
Am I missing something, or am I in inherent danger due to the bridge I've soldered between the contacts? (Just kidding)
Edit: I've just looked it up. There are a lot of aftermarket "battery holders" available. I guess mainly because of the above mentioned issue. I don't know if Microsoft ever sold original batterypacks.


texts:
I have the following circuit for which I need to find the time constant:

Would it be correct in assuming that the only relevent resistances are R2 and R4? So then the time constant would simply be (R2||R4)C? Or am I missing something obvious?

Thanks


texts: Why is the reverse biased zener diode used for voltage regulation?

texts: I would expect a forward biased regular diode to be used. Especially in applications in which you don't expect a change in current direction. Is the curve more predictable in the reverse biased state?


texts:
I am reading this link about ferrite beads and in page 2, figure 2, there is a SPICE circuit to emulate the ferrite beads frequency response.

Why there is an AC Current Source in the circuit? Why just dont "plug" the bead to the AC Voltage sorce and Ground and run the simulation?


texts: 12 pin circular connector with twist lock What kind of conn it is?

texts:
I'm trying to find whose product this. I have an another one with yellow and black twist lock. So might be the twist lock color is variable.
Anybody can send an offer or anybody recognize it?
Thank You!


texts:
When a dc voltage source is connected with a pure inductor

And the switch is closed

We get a change in voltage across inductor and along with it a also an attempt to change the current across the inductor.

We get equal and opposite voltage across inductor against the source voltage(Faraday and Lenz law) at t = 0.

But then as time passes we get increase /change in current across the inductor at a constant rate. di/dt = V/L.

Now when we connect ac with a pure inductor.

We have always changing voltage across the inductor and consequently always changing current across the inductor.

So can i assume that for every infinitesimal change in voltage and current across the inductor in case of ac there will always be equal and opposite voltage across the inductor which will block the current initially for a while for that infinitesimal change and then will allow the current to change at a constant rate for that infitesimal change of voltage and current?


texts: microcontroller resetting and hanging problem

texts:
I am controlling a 16x2 LCD and a high electrical device using ATmega8l microcontroller but if there appears a spark in AC power line due to high electrical device then my microcontroller goes to reset or unreadable character on LCD or controller goes to hang and I have to reset.

please help me what should i do ?


texts:
Why are series stubs difficult to realize in microstrip technology?

I read this statement in some text about the realization of microstrip filters, in which the solution for this problem is that of realizing them through parallel stubs related to the series ones by kuroda identities.

With Series Stub I mean a series short circuited stub, connected as in the following picture (C)


texts: A good technique for removing 50-pin SMD CF/MD card slot with Hot air

texts:
I have a piece of equipment that has a CF/MD card on it. Somebody tried to force the card in and broke 2 pins off. I managed to replace the two pins temporarily, but it was kind of a hack job, but it works for now. What I want to do is order a replacement part (the part is ELCO 5620). I have a hot-air rework station but I don't have very much experience with it.

Can someone give me a run-down on technique I should use with the re-work station to remove a 50-pin CF/MD card connector. For example, what temperature to use, nozzle size, how long to heat, how to remove the component, how to prepare the site to put the new one on, etc.

Or maybe a link to a good tutorial. I have looked around for tutorials, but all I see is info about removing SMD chips and resistors, which typically aren't surrounded by easily damaged/melted plastic.


texts:
I am doing a project to make a test box that would test the switch module in the photo below. Please see circuit diagram below for inside of the switch. Please note this switch is not an ordinary switch has it resistors inside which is more complex.

So far I have designed the test box circuit using various way and methods  I have used  555 timer circuit, Transistor and finally using NAND logic gate. The best option was the last one using NAND Logic gate as it worked the way I wanted by using a 10k resistor and 3 LEDs using the truth table however due to my switch circuit on the inside this would not work.

A B  Output
0 0   1
0 1   1
1 0   1
1 1   0

This NAND gate logic worked on circuit simulation tool after using two ordinary switches. However, when I try to integrate my tester box switch to the switch I have noticed my switch is much more complex has its got a circuit inside with resistors which I couldn't integrate the two circuits.

The only other idea I have is to do this using Arduino and program it maybe.
Can anyone tell me ways to do this, as I have run out of ideas now?

 Reference A

 Reference B

 Reference C

 Reference D

PS:

@jonk Apologies for misclarification yes the buttons are momentary and no it's not latching magnet motion. Also, its not random switch its got circuit inside which indicated above, my goal is just to test the switch if there are connected or not and their state by showing me LEDs to indicate that. ''wanting to push those buttons to verify they work correctly?'' Yes I want to verify if they work and connected

Response to @Transistor's comments:

Is someone is going to connect the switch module, press the buttons in all four NAND combinations and watch the LEDs? - Yes, the switch is going to be connected with the NAND circuit and watch the LEDs if they are connected and works.
Does the test circuit need to confirm the presence of the four resistors? - yes, the resistor circuit should confirm the four resistors including the switches, In fact, it should configure the switch circuit diagram and it should work by simulating and integrating with NAND gate (tester box circuit).
Does the test circuit need to check the values of the four resistors?  - Yes, it should.
Your simulation doesn't show the four internal resistors. Why not?  - The four resistor from my switch circuit diagram has not been simulated yet - the simulation circuit above is my tester box circuit and however the 2nd image is the switch circuit from the supplier datasheet.
Why do you require a NAND? - This NAND logic works well to what output I want to achieve, I want the output to be on what input is inserted. If any other circuit suggestion do please let me know.

Another Response to @Transistor's comments:

Sorry, I think I have confused you and you have misunderstood my question. Now I have reference each image clearly i.e (References A-C). So the switch unit in Ref A is what I am trying to test, the switch unit has got an onboard installed circuit to see Ref B, Also please note that REF B circuit diagram is already been given by the supplier. In other words, Ref A&B are equivalent. As you can see from the circuit diagram REF B that which doesn't have or contain any a power supply at all. So Ref C is just a draft circuit that I was hoping it would work and I could able to test switch unit in Reference A;- by connecting REf B to the REf  C (the circuit I have created ) to test the switch unit REF A.
So just to sum up and answer your question ''What two circuits? '' One circuit is Ref A and other  REF C. Also this Ref A switch unit is much more complex to test since its got 4 resistors inside and 3 pins see an image and its not just an ordinary simple switch(Reference D)


texts:
I have a GEL battery 225Ah. After fully charging it, it holds a 13.1 - 13.0 volts after 24 hours. I tried to put it on load (20 watts light) for 2 hours and voltage droped to 12.5 volts. I know that battery is bad. but after an hour without load and without charging the battery voltage rised to 12.8 volts. Any idea on what is happening here?

Note: the battery was part of my battery bank which was 6 x 225 Ahr on 24 volts system. Three batteries went dead as a sudden and dropped voltage to 11 while the others were 12.8 (at 6 am). I tried to revive one of them and the result was the first situation.

Details:

Batteries are 4 years old.
bat. temp between 20 - 25 celsius
I use an MPPT charger giving a 28.8 volts on bulk stage, and 27 volts on float stage.
I do use it while charging but My MPPT calculats the battery current and I never let it goes to negative while charging.


texts:
I came across this transformer, and there are a few points of the datasheet that seem unclear to me. I can't seem to find any references for what exactly they refer to, so I'll ask here:

Where the datasheet says Inductance @ Irated, does that mean the primary inductance, or the mutual inductance, or something else entirely?
Likewise, I assume Irated is referring to the primary-side rated current, not the secondary side?
When it gives a value for Leakage Inductance, should that be assumed to be the leakage as seen on the primary side?

And finally: This is a badly-written datasheet, right? I've seen other datasheets that actually define exactly how each parameter is measured, and that seems like it would answer all of my questions if this one had that.


texts:
I'm currently designing a 4-layer PCB for a SOC (Allwinner A33 to be precise, 0.8mm-pitch BGA) with one DDR3 chip. Per DDR3 routing requirements, the traces need to have 50-ohm impedance. Also, they need to fit between BGA pads and breakout vias, which limits the trace width to max. 5mils.

To achieve 50-ohm impedance with a 5-mil microstrip, the dielectric layer needs to be about 3-4mil thick. Currently, I'm preparing to manufacture a few prototype pieces, and I'm having trouble finding a fabrication service online which would offer the required stackup.

So, the question is: how do people get such prototypes manufactured?


texts: Are "bootleg grounds" really more dangerous than other single-point wiring failures?

texts:
Continuing my attempt to understand the use of grounds in modern electrical service: There are numerous posts illustrating why a "bootleg ground" (ground connected to neutral outside of an AC service panel) is dangerous.  But is it fundamentally more dangerous than other similar wiring faults that can occur?

By code, I gather that the introduction of line voltage onto the third "ground" line in an a electrical service is always the result of a wiring fault.  It's unclear to me that the ground service loop has improved safety.  I can see examples where it averts a danger, but doesn't it also introduce hazards where others did not previously exist?  For example:

Single-device fault: In a two-conductor service, without the ground, a device wiring fault could either expose users to line voltage (leading to possible death) or else short the circuit, causing the circuit breaker to cut power.  If the device is grounded then the device can be constructed with a "grounded case" which, in the same fault, attempts to catch and divert the line voltage to the ground so the user doesn't contact it.
Ground wiring fault: If you put a grounded device with a ground fault on a circuit with a broken ground, now all grounded devices are carrying line voltage on the ground.  In fact, because device grounds are designed to do their best to isolate users from voltage, they tend to connect to cases and enclosures users are likely to contact.

So it seems like adding grounding to an electrical service can possibly avert a hazard in device fault scenarios, but at the expense of introducing a new hazard in the event that occurs together with a service ground fault.

Now, I suspect I'm missing important elements of this analysis, since grounded service has been code for a long time.  Can someone fill in the blanks to illuminate why grounding AC service is clearly better then two-conductor?


texts: SI derived units: Another name for the Volt

texts:
\$ V = \frac{Kg \cdot m^2}{s^2A} \$

I know it's basic but I was having a hard time understanding the relationship between volts, ohms, watts, amps and ohms until I broke everything down into base units. The exercise got me thinking about alternate names for the volt. For example, a joule can also be called a newton-meter or a coulomb-volt.

The powers in SI-derived units indicate relationships based on rates of change. For example:

\$ m \$ - distance
\$ m/s \$- velocity, change in distance per second
\$m/s^2 \$ - acceleration, change in velocity per second

Consider:

\$ Kg \cdot m^2  \$ which measures moments of inertia.

That makes volts the acceleration in moments of inertia per amp. That isn't the most helpful observation considering there isn't anything rotating.

Maybe consider:

\$\frac{Kg}{s^2A} \$ which measures Teslas of magnetic strength.

That makes volts... Teslas of area?

Are there any helpful unit-based alternate names for the volt?


texts:
I'm looking at using the following part, S4PM:
Datasheet

The part has a Vrrm of 1000V. The mounting pad layout shows a separation of 0.81mm between cathode and anode.

This is well below IPC2221B clearance for 1000V (should be 2.325mm, for a coated board). How can this part be rated for this voltage?


texts: Device-to-device/machine-to-machine wifi IoT system -- pushing message/action to a connected device

texts:
I am not sure if this is the best community for this question, but I couldn't find one dedicated to IoT. Or should I ask on StackOverflow?

I am looking to build the following IoT system using WiFi devices:
-- total 3 wifi capable devices
-- devices #1 and #2 are acting as sensors. Assume they are simple ON-OFF type sensors (very infrequent state change)
-- Device #3 is acting as an actuator, controlling an output ON/OFF
-- Required functionality: The Device #3 should turn its output ON, when both device #1 and #2 read 'ON' on their sensors

I have spent today searching for ways to achieve this. I looked through Particle Photon, Sparkfun Thing, etc. for the devices and Thingspeak, data.sparfun.com for the cloud/internet part of it. But I couldnt see how I could achieve this.
What is not clear to me is:
--- how to get the message to the actuator device to turn its output ON?? Poll or send a message? how to do either?

Here is one potential approach I thought of:

Use Sparkfun Thing for the devices
The sensor devices use HTTP to post the sensor data to the cloud when they detect a change on their sensors values
The actuator device, will periodically poll (by issuing HTTP GET requests) the cloud and fetch the sensors' data. And when it sees both are ON, it will drive its output ON

The problem with this is that I need quick reaction, i.e. once both the sensors read ON, I need the actuator to turn the output ON within 2-3 seconds. This means, with the "polling" method, I need to poll quite frequently, and I am not sure whether the rate-limits on Thingspeak and data.sparkfun.com will allow this.

So to summarize my questions:
--- how to get the message to the actuator device to turn its output ON?? Is there a way other than polling, where a message can be sent to the device?
--- Any suggestions on which platform (photon, sparkfun thing or any other) to use for this kind of project
--- Any other (even totally different) suggestions on how to achieve the system with the required functionality described above

Thank you.


texts: Art of Electronics figure 5.87 (revised)

texts:
The circuit below comes from the errata of The Art of Electronics. Why is the circuit in Figure 5.87-B (bottom) correct?

As drawn, 50 mA at output will mean -5V at the inverting input of the Op-Amp. Actually, I would expect that 50 mA causes +5V and the circuit is at the Full-Source operation point (1V/10mA).

Should the errata be corrected? In the original figure (printed book), the inputs of the In-Amp are swapped.

Thank you in advance!


texts:
I have twenty LEDs that I want to light up. I planned out a few possible circuits, which I describe below along with a few questions. Would any of them not work, and why? Anything else I should be taking into consideration but haven't? The LED has the following specs:

Vmin: 2.8V
Vmax: 3.5V
If: 20 mA

From what I understand, the Vmin is essentially the same as Vd in this diagram, so the current will be 0 until it reaches that voltage. Is this correct?

If the LEDs are connected in series, that means that I'll need 20*2.8V=56V in total to get current passing through every LED. I calculated the approximate amount of power necessary (60V*0.02A=1.2W) and compared it to the amount that can be provided by a typical AA battery, which I've been told usually provide around 800mA of current (1.5V*0.8A=1.2W). Seeing as they're the same, I'm pretty sure it'll be possible to step up from a single AA to what's needed to light the LEDs. So far, I know of the SEPIC, which I'm reading up on right now. Is there a better way of accomplishing this? Possibly without needing inductors?

Another solution I've considered is connecting them in parallel, which I recall reading somewhere that it's a bad idea unless there's a resistor in series with each of the LEDs. Two AA batteries in series would be enough in this case, providing a 3.0V potential across each branch. Since the LED takes 2.8V, the resistor would take up the remaining 0.2V, and to get a 20mA current, I'll need a (0.2V/0.02A=10ohms) 10 Ohm resistor.

I could also plug it into an adapter which converts the AC electricity from the outlet to 15V (the current rating on the adapter means the maximum it can give and not the amount it'll always give, right?). In this case, I could separate the LEDs into four groups of five (which is convenient given their layout), each LED in a group of five is connected in parallel to each other, and the four groups are connected in series. That would give a voltage of (15V/4) 3.75V across each group of five, and since the LEDs in the group are in parallel, they'll each get 3.75V too. The current needed would then be (0.02A*5) 100mA. The voltage across the resistor in series with the LEDs is (3.75V-2.8V) 0.95V. The resistance needed would then be (0.95V/0.02A) about 50 ohms.


texts: Measuring humidity with Honeywell 5030/5031 sensors

texts:
I'm trying to hook up Honeywell's 5030 humidity sensor (datasheet here). Figure 10 (on page 7) of the datasheet has a typical application circuit, only I'm not sure why they have also included a resistor between the output and ground pins. The resistor is not mentioned anywhere else in the datasheet (i.e. the humidity-voltage curve does not include a parameter for this resistor). Is the value of the resistor relevant? What is it supposed to do? Does it change the response curve at all?

I can see that the resistor is labelled 'minimum load', but I'm not sure what that means either. Sorry if this is blindingly obvious, I'm CS trained and jumping into embedded stuff so some of the electronics is a bit confusing :)

Leon


texts: Operation of a Growler to test armature shorts

texts:
Can someone explain to me how a Growler for testing electric motor armatures works please? I have obviously read the Wikipedia Growler page but it is still foggy. So the growler unit acts as the primary of a transformer but how does the stator winding (I am testing on a stator) act as the secondary if there is a short and induce a vibration (or force) in the feeler? Also, I need some clarification on the part of the growler that is attached to the stator (but not the feeler and not the primary unit). I am going to see one in operation soon and can update this after I have viewed it in operation.
Thanks!


texts: Capicator voltage difference on a 1990’s CRT circuit board

texts:
I have (4) 25v 10uf capicators to replace on a CRT circuit board. I have some new 65v 10uf caps on hand, will they work? Is 2.5 X the original voltage to High? The CRT is a low resolution game monitor from the early 90’s
Thanks for your input.


texts:
I have a LM317 setup as a 3.3V regulator. I am getting 12V input from an Agilent Technologies E3631A Variable DC Power Supply. On this same board I also have a LM7805 regulating to 5V. All of my grounds are connected together.

My problem is with the 3.3V line. When I measure the line with my fluke, it reads 3.63V. Way above where the regulator should be putting the line. However, when I hookup the ground line from my osciliscope cables to the ground on the board, my multimeter reads out 3.31V (within the expected range). Why is this line floating so high, and how can I fix it?

As a side not, the Power Supply does have a ground terminal. I tried using that with the board instead, but when measuring the voltage from V+ on the power supply to earth ground. I get a varying range of small voltages (not the 12V that the power supply is putting out). Also the 5V line does not change depending on if the oscilliscope probes ground lines are connect.

A diagram of the circuit:

Thank you.


texts: What is the purpose of the ground in this diagram?

texts:
I'm trying to read a throttle position sensor with my Arduino Mega. This is the schematic for a normal TPS. It's a basic potentiometer.

(source: autolabscopediagnostics.com)
However, this particular TPS only has 2 pins coming out. There's no ground, there's just the 5 volt reference and the signal return. I have one pin hooked up to the 5Volts on my Arduino and the other hooked up to an analog pin, which I am reading with analogRead. I'm getting strange readings at different positions. At position zero, it jumps around at around 300. As soon as I turn the sensor at all, it automatically jumps to 1023 and stays there.
What is the point of the ground in that diagram? What am I missing here, and how does that tie in to the odd TPS readings?


texts: Can I feed same digital signal to two DACs and take the average of the outputs of two DACs. What precautions should be taken?


texts: Measuring sensor noise on analog channels of common single board computers

texts:
Using the "MATLAB support package for Arduino" package, I am trying to characterise the analog input channels on an Arduino Uno board. The underlying assumption is that all sensors are inherently noisy and far from perfect. After all, the arduino has got only a 10-bit ADC, and there should be at-least some quantization noise, if not pick-up electrical noise.

But when I ground any of the 5 analog pins on the Uno (i.e. a hook-up wire connected between analog channels and the on-board GND pin), all that MATLAB can read in software is a perfectly flat '0' (ideal voltage) even after collecting analog data for long time-periods. This seems a bit strange to me, as the analog sensor on the Arduino is certainly not super hi-fidelity.

i would really like to characterize the analog channels (for coming up with the "R" (i.e. sensor covariance) matrix when I later implement a Kalman filter using batch analog data collected from this Arduino. Any help towards this is much appreciated.


texts:
This MOSFET IRFBG30 is being used in an old design. It even has a little heat sink attached. The FET is used as a current limiter. During normal operation, a current about 13 mA passes through it. Under certain condition, the same FET is going to switch a 1.4A inductive load for a brief moment. What I'm thinking is to redesign this board and replace that FET, with this one: IPD95R1K2P7 which is a surface mount FET. I would use the PCB as heat sink. I note that the new FET has VDS: 950V and the old one 1000V. But I think this shouldn't be an issue, as I expect the max VDS to reach 900V under some critical/unwanted condition. Of course, this time the IRFBG30 wins. However, the IPD95R1K2P7 has lower RDS.

Is this a good idea?

EDIT: Added the circuit


texts: Using Op-Amp to form a uni-gain buffer, what happen if IN+ is floating?

texts:
If an amplifier is supplied with VCC and VSS and form as a buffer, what is the amplifier's output voltage once the positive input pin is disconnected(floating)?

Is there any method to calculate out the output voltage?


texts: Chargers for modern devices, understanding compatibility

texts:
When a device (say a modern MacBook charger or GaN charger) lists modes, such as...
Max Power Output
66W
USB-C1
65W Power Delivery 3.0, 5~15V/3A, 20V/3.25A
USB-C2
65W Power Delivery 3.0, 5~15V/3A, 20V/3.25A
USB-A1
36W Quick Charge 3.0, 5V/3A, 9V/3A, 12V/3A, 20V/1.8A
Power Input
AC 100-240V 50/60Hz 1.7A

If I'm say charging a 60w device from this "65w" charger, is all I care about "syncing" the voltage.
i.e. I need the device being charged to be able to sync at 5->15 or 20v, but I don't need sync on the amps.
so the device can draw as much as it needs of the 3->3.25 amps, once it has a happy sync on the voltage?


texts: I'm trying to generate a 15 minutes alarm using RTC in MSP430F5438A microcontroller from Texas Instruments. What values should I put in the Interrupt registers. I have tried putting 0x95 in RTCAMIN register but it generates an interrupt at 15 min, 1 hour 15 minutes, 2 hours 15 minutes, and so on. I want the interrupt at 15 min and only one time.


texts: How can a Ultralow Voltage Step-Up converters start up?

texts:
I've read about step up converters working from unbelievably low voltages (20mV), namely the LTC3108. How can circuits even start at those low voltages?
Diodes, FETs and BJTs shouldn't switch at 20mV.

What is the concept behind it?

Link to the actual IC


texts:
We have a product which is to do resistance measurement. The simplified schematic is as below. A 50mA DC current flows through the resistor, and we measure the voltage on the resistor's terminals. There are three relays from OMRON, G4W-2212P-US-TV5-24VDC. And because that relay has two contacts, so we use them in series. That is both RLY2 and RLY3 actually two contacts in series.

Today, we encountered an interesting problem. When all the relays closed, \$V_{CD} < V_{AB}\$, the 10 ohms standard resistor was measured to 9 ohms or so. It's not surprising that there must be different voltage drops on the two relay branches. What surprised us is if we break the current path and re-close it (either control RLY1 or break the loop manually), then the resistance measured is correct. Considering the relays have been in sock about two years, we doubt their contacts may not in good situation, so we break them and do a contact cleaning. Then all are OK.

The problem is resolved now. But i have some questions:

Why breaking the current loop and re-closing it will work?
Is it normal for a relay without using for 2 years to behave like this? Or we choose a relay not suited for our applications?
Beside breaking them and clean the contacts, are there other methods to make them work?

Update:

Thanks to MarkU, he points out the doc states the relay is not suited to switch micro loads
less than 100 mA, but i still want to known the answer to other questions, thanks.

simulate this circuit – Schematic created using CircuitLab


texts: differential pressure sensor gives oscillated result

texts:
I'm trying to measure water pressure of water pipe by exactly replicating this : http://www.practicalarduino.com/projects/water-tank-depth-sensor

When I tested the sensor (by leaving both inlet free, and printed the result directly to Arduino's Serial), I got a wave-like output. The sensor gave high output (1023) then steadily dropped to 0, and then increased again.

I've also tried to test the sensor by directing both output (+Vout and -Vout) to Arduino's analog pin. And the result stayed the same.

My question is: Is this condition normal? I have no experience before with pressure sensor so I have no idea if this is working correctly or not.

PS: I've tried the component by using 9V adaptor. From the datasheet (http://www.nxp.com/files/sensors/doc/data_sheet/MPX2010.pdf) I found that

Vs = 10 Vdc

While Vs = supply voltage, what does Vdc stands for? And what's the difference it has with Vs?

Update : I found this https://stackoverflow.com/questions/2851078/analog-readings-on-arduino-returns-wrong-values and it seems the case is almost similar to me. Should I do the same with my MPX2010 from the output pin (even though MPX2010 already had its own ground from the 1st pin)?


texts:
I am to size a 3v3 voltage regulator,
It gets at its input 12VDC maximum. And the load can consume up to 150 mA (few leds, 20 NMOS control, ADC control, microntroler supply...) and ambient temperature can reach 70°C.
I have to be surface and cost efficient in my choice.
I'm struggling with chosing the regulator because I don't know weither the regulators I found are underdimensioned or overdimensioned.
I found those regulators:
MC33375 /
ldk320 /
MCP1702
What do you think of them ? On some of the datasheet there are formulas but I didn't understand how to use them, as the RthA can vary depending temperature and manufacturers usually indicate its value for TA = 25°C (and not 70°C)
Thank you for your help


texts: is this li-ion battery still safe to use?

texts: While replacing my phone's screen I seem to have scratched and maybe damaged the battery. I don't know much about li-ion batteries so I'm wondering if it's still safe to use, or if I should look for a replacement.


texts: Why is this opto isolator input turning off so slowly?

texts: I feed a nice square wave into Q1/2, and on U40/1 I see a full turn off take almost a millisecond! What is happening, and can I fix it (ideally by not adding components)?


texts:
I’m rewiring a Desktop CNC controller and came across the attached info on one of the internal modules (variable frequency drive).

The two 220v mains power inputs are labelled R / S / E where I was expecting L / N / E or similar for live (active), neutral, and earth.

What does R / S stand for and is this a standard notation that I haven’t seen before, or something else (perhaps a translation issue)?


texts:
I'm currentlry doing a redesign of the Arduino Due board to include some additional features I need. Browsing through the Datasheet of the ATMSAM3X8E atmel chip, I noticed that the 12Mhz Oszillator used for the Arduino Due differs from the descriptions in the datasheet. The Due oszillator has a load cap. of 20pF and they use two 22pF externals caps. The datasheet specifies an allowed crystal capacitance load of 12.5 to 17.5 pF and external caps < 10pF (Datasheet p.1397).

Every schematic I found doing an adaption of the arduino due uses the same setup as the Arduino Due.

I already have a first prototype made where I used the setup from the Due schematic and it seems to work. Now that I discovered this, I'm not sure wether to adapt this and risk that the redesign does not work for some reason or just ignore this...

Does anyone have experience with this or any thoughts?

Thanks

EDIT:
It gets better :-). Apparently the BOM I used for the first prototype was an older one and had even another crystal in it. So the current prototype runs with an 12MHz Oszillator with a load cap. of 10pF together with two 22pF external caps. Apparently this does not cause any (at least obvious) problems. I really do not have any experience regarding those crystals and wonder why those faults obviously dont matter... :-)


texts: PWM frequency and control system sampling frequency in dc-dc converters

texts:
I am trying to control the output voltage of a simple dc-dc buck converter, which is digitally controlled. The output voltage is sampled, and the control algorithm is run, at every \$T_s\$ seconds, while the PWM frequency is \$ f_{sw} = \frac{1}{T_{sw}} \$, with \$ T_{sw}= 0.1\times T_{s}\$. In other words, the sampling frequency and the frequency at which the controller is run, is much lower than the PWM frequency. I.e. the controller is "undersampled" (please correct me if this expression is inappropriate here).
What does this difference in control sampling frequency and PWM switching frequency imply in terms of controller design? In the literature, the controller sampling/running frequency is most of the times chosen the same as the PWM switching frequency, and I could not find a source explaining what happens when the controller runs slower than the PWM.
Thank you


texts:
I found this "Plant Grow LED light" circuit on the Internet and I wanted to know if:
(Please don't feel pressured to answer all my questions.  You can just answer a few only if you like.)

this is correct?
the best way to build this circuit?
is the cooling fan necessary?
what is the heat threshold necessary to implement a cooling fan?
how can I determine the amps correctly of 12 volt power supply if the label on the
power supply is wrong?  I use a 120 volt outlet here in Toronto, Canada.
I have old 12 volt power supply but it gets too hot to the touch.  Should I discard
that?
Is R1 0.20 ohm resistor the same thing as a 20 ohm resistor?
How can I add a switch with a potentiometer?  What kind of ohms?
Could a 555 timer be used to increase the amount of LEDs to double by alternating 2
separate circuits back and forth - on and off? This would appear to be 20 led light on
simultaneously but really a set of 10 go on while the 2nd set of 10 turn off and then
in a split second later this reverses the 1st set of 10 turn off and the 2nd set turn
on. And so forth.

I'm wanting to grow Orange Pixie Tomatoes.(I bought the seeds from Tomato Grower's Supply Company  I'm just a customer, have no endeavor with them, just in case your curious about that tomato cultivar.)

The circuit to be built would hang 4 inches above the plant.  I'm scared that if I purchase a 50 WATT(includes a cooling fan) grow light this would catch fire when I'm sleeping or away from home. Thus I thought a 12 volt circuit would be safe.

Later I would like to show my final draft which will include white LEDs to produce better nutrition in the tomato plant. Many grow lights now come with between 10.66% to 25% white lights to produce carotenoids in the plant as a health benefit I believe.  So thats one mistake the circuit has.

This is my first time here in posting.    Thank You for reading this.


texts: Eagle: How do I edit the dimension layer?

texts:
While creating a via, a drill shape somehow ended up on my dimension layer. Even though I've deleted the via the drill hole remains and produces an error. How can I edit the dimension layer and delete the drill hole?

Screenshot attached. Only the dimension layer (layer 20) is shown.


texts: Purpose of rheostat in measuring resistance

texts:
I was given task to measure the resistance of different length of same conductor to find the relationship between length and resistance. The circuit diagram is something like this:

The resistance,R is replace with different length of the conductor  thorough the experiment. The rheostat is adjusted so that the ammeter reading is always the same for the different wire length.

My question is why the rheostat is needed in this experiment to adjusted the current. Isn't that we can get the resistance by dividing the voltmeter reading to ammeter reading, even without the rheostat?


texts: Microstrip transmission line impedance calculation

texts:
I'm attempting to calculate the necessary trace width of a PCB transmission line in order to have a characteristic impedance of 50ohm. However, different online calculators are giving me slightly different results.

My PCB substrate is FR408 from OSHPark. So, the dielectric at my 5-6GHz frequency range is 3.66, the trace height is 1.4mil and the dielectric thickness to the first intermediate layer (this is a 4-layer board) is 6.7mil.

This Mantaro calculator tells me that I need a trace width of 11.98mil. Chemandy on the other hand tells me 14.72mil. 3mil seems like a substantial enough difference. Is one of these calculators more accurate than the other, or should I use a different equation altogether?

EDIT:

Looking at the equations, Chemandy provides an explicit calculation for the effective dielectric (due to the fact that one side of the microstrip is adjacent to air, as explained here), whereas Mantaro does not. If I use the effective dielectric provided by Chemandy with the Mantaro calc, the difference between the results roughly halves, but does not disappear. This might explain part of the discrepancy, but is not a full explanation (and still does not specify the right equation to use).

The reason provided in the edit is incorrect. I found the exact equation Mantaro uses in High Speed Digital Design by Johnson, where he explicitly states it takes into account the effective dielectric.


texts: What is the right voltage to charge a flooded lead acid at CV? Also it got pretty warm while filling up acid

texts:
Recently purchased a Yuasa PowerSport (6N5.5-1D- 6V 5.5Ah) bike battery. Since Amazon does not sell it with the acid it has to be purchased separately from an auto store or self prepared. I went with the latter and prepared a 37% sulfuric acid solution using a 98% ACS H2SO4 reagent.
If I'm correct flooded Lead acid batteries use 36-38% sulfuric acid electrolyte.
I had prepared the acid solution yesterday. A little while ago I added the prepared acid to the battery and immediately upon adding the lead plates died/bubbled a bit and the battery is getting warm (not hot.) Is this normal or something is wrong with my battery?
The battery shows a voltage of 6.62V.

While charging the battery for the first time can I use a constant voltage charger?
Can the charging voltage be 7.2-7.5V like SLA or should it be lower for a flooded cell?


texts: How do I calculated the outputted AC voltage of an H-Bridge inverter

texts:
I am trying to build a wireless battery charger. Below is a rough idea of what I want to achieve.

Currently I am having trouble with the inverter circuit that is shown below.

I understand that this inverter circuit is converting DC to AC by using an H-Bridge configuration with the use of MOSFETS, MOSFET Drivers, timer IC and Inverting IC.

My question is how do I calculate the AC Voltage produced by this inverter if I am to supply 12V DC and set the working frequency to 100khz for wireless power transmission through a litz pancake coil?

I know that regular inverters convert 12VDC to 240 VAC with the use of a transformer. I have tried looking at the 74HC4049N inverting IC datasheet and am unable to identify the outputting AC voltage.

I need to know how much AC is produced in order to correctly build a Diode Bridge rectifying circuit on the battery side.

Any Help will be sincerely appreciated.


texts: Is it possible to connect CSI-2 camera to CSI-1 port?

texts:
I'm not hardware engineer and I have no idea if it would possible connect CSI-2 4k camera to CSI-1 port in snapdragon board?
Do I need any adapter or it will work straightaway? Is any other pitfalls I may expect?


texts:
I notice that clamp-type current meters range in price from a few dozen dollars to a few hundred, but current probes for oscilloscopes cost significantly more, with many close to $1000 and some well over $4000. Why are the oscilloscope current probes so expensive? Are they built by princes? Do they contain coils of solid gold wire?

I get that these are fairly low-volume items, and that they need to be calibrated and probably have circuitry that compensates for various errors, but isn't that also true of current meters? Is there something special about the probes, or just market forces at work?


texts: Using HC05 Bluetooth SerialPort to stream music/voice via Arduino

texts:
I'm considering streaming music/voice over Bluetooth serial link (via HC05) from PC to Arduino. By doing this, there would be no need for a SD card. Here is the questions I have.
Any help is appreciated.

1- Arduino Uno doesn't have D2A. Is the tone.h library enough for this purpose? Can we use an external D2A instead? What about other Arduinos?

2- Maximum supported baud rate for ITead's HC05 is 460800 (datasheet here).
Based on searching the net, people suggest using a lower baud rate to increase Signal/Noise or even range. Does UART's baud rate(aka a logic layer) affect range/quality?

3- If we use 460800, we get 45 KByte/s data rate. If we use 115200, we get 11.25 KByte/s data rate. Are these rates enough for A- Voice and B- Music streaming?

[UPDATE]
Various audio quality samples are provided here (from 8Kbps to 192Kbps).
Here is a list within reach of HC05's maximum baud rate:
1   KByte/s -> voice, music
2   KByte/s -> voice, music
....
10 KByte/s -> voice, music

10 KByte/s or 80 Kbps corresponds to baud rate = 115200 and we can quite clearly hear the contents. So can we say baud rate is not the limiting factor here?

Thanks


texts:
So I have a power supply for an old Molar Mac that repeatedly chirps and does not power on. One issue is that the thing looks like it is in perfect condition (no bloated caps or anything). I cannot try to power it on without load because it has to be connected to the analog board (as far as i can tell, i need to look at it a little more) to even try to power on. I have heard if it is a power supply issue (not a connected device shorted/pulling too much) it is usually the caps or diodes. I am a noob, so how would I go about testing something like this?
Thanks!


texts:
I have been set the task of creating an h-bridge that can control a 12V DC Drill motor. Below is a slightly modified version of the document I have been given to help me get started:

I don't understand why only one of the MOSFETS is being driven with 15V, and the other 12V. I believe it would be acceptable to drive both with 15V. As this is only half of a complete H-bridge, I have drawn the other half and researched some component values and included these in:

Could someone please help me understand the purpose of the resistors and diodes used, and which grounds are what as I understand that the NME1215SC isolates each 0V.

EDIT:

After looking at the comments and answers, I have come up with the following schematic. Does it look correct?

Many thanks for your help with this!

ANOTHER EDIT:

As per Andy aka's corrections, here is the modified schematic:


texts:
I am learning some concepts of USB OTG recently. When surfing wikipedia,I came to know that, OTG supporting devices are playing dual role and it will have mini AB type receptacle or micro AB type receptacle.

To act as a host, the OTG supporting device must be connected with mini-A or micro-A cable. To act as a device, it needs to be connected with mini-B type or micro-B type cable.

Wikipedia says -

  "The device with a mini-A plug inserted becomes an OTG A-device, and
  the device with a mini-B plug inserted becomes a B-device (see above).
  The type of plug inserted is detected by the state of the ID pin (the
  mini-A plug's ID pin is grounded, while the mini-B plug's is
  floating)."

But doubt comes when I come across this image I attached. It has mini-B type receptacle for it's audio system. In order to insert a pendrive, the user need to have an adapter which should have mini-B type on one end and standard A type on the other end. So, possibly the audio system in the car can only detects that mini B type cable is connected with it. If this is the case, the audio system is supposed to works as a device instead of host.

But, the audio system detects pendrive and starts to play music from it. This is a chevrolet beat car audio system. Is this contradictory to the theory said in wikipedia?

clear out this doubt please?


texts: PIC18F4550's internal oscillator block power consumption

texts:
I started learning the PIC18F4550 recently, and I came across the internal oscillator segment where an 8 MHz internal oscillator source is divided into multiple clock signals of different frequencies. Does dividing the clock source save any power?
(Because the oscillator source is the same, the power consumption should be the same or maybe more due to the frequency divider. However, my instructor indicated that the answer to this has something to do with delays, and I can not seem to figure out what it is)


texts: Light dependent resistor (LDR) switched LED-circuit

texts:
NOTE! The LDR has a minimum val = 2kOhm and a max. val. = about 5 MOhm

Im trying to build this circuit for my radio station. I would appreciate som help.

Your general opinion about the functionality of the circuit. (It is my first completely own-made circuit)
Some thoughts, let me explain.

Well basically I have more than one question, but lets start with the main focus. So the whole idea of using the Zenerdiode is that I want that when the light is of (the LDR is attached to a tiny LED-lamp on the mixerbord, wich goes on if someone is calling the radio station) and the LDR has a value about 5 MegaOhm, there is not enough voltage over the Zenerdiode, making it act as a open (no current passing through). In that case, in my opinion, there will be no current and likewise no potential relative to ground in the point between the diode and R2. This would close the transistor. No light on the mixerboad, no LED1 2 or 3 is lit.

In the case where the mixerboard LED is on, well the potential after the LDR is much higher (hopefully around 7-8[V]) so the Zenerdiode will now push trough current, and the potential after the zener will appear. This will open the transistor and the LED's will be lit.

My main problem, and the reason why I designed it like this is because it is really important that the transistor is acutally "closed", and the LEDs are not lit when they are expected to not be lit. Basically, I tried to quantify a "light on" (on the mixerboard) with a specific voltage on the gatepin of the transistor, via the zenerdiod.

Is this viable?


texts:
I'm trying to build an IR Barrier with an 555, a sfh4547 and a tssp58038. Here are the datasheets:

http://www.ti.com/lit/ds/symlink/ne555.pdf
https://www.osram-os.com/Graphics/XPic0/00209793_0.pdf/SFH%204547.pdf
http://www.vishay.com/docs/82479/tssp58038.pdf

This is the schematic of the emitter:

An this is the schematic of the receiver:

I have tested that the emitter has a frequency near 38khz
but always have a 5v output in pin 1 of the tssp58038. I don't know how to make it work.

Update:
Osciloscope at 1v and 5us.

This is the NE555 output:

This is the base of the Q1:

This is between Q1 and D1:

This is between D1 and R5:


texts: Convention on pin shape association for headers on a PCB?

texts:
I want to use such headers below as terminals on PCB to solder power or signal wires to the PCB.

Is there a convention for square or circle pins association? I mean should square always be the GND or?


texts: Bluetooth Low Energy IoT device compliance

texts:
I´m designing a bluetooth IoT BLE device and have heard that making use of the Bluetooth logo in the device implies an annual fee for Bluetooth SIG.
I would like to know if this only applies to the bluetooth logo and not to the technology itself.

The device will be free and inistalled by our company so it doesn´t have to have any marketing/commercial attraction for the final user.

This is, if I design a bluetooth device but don´t print the bluetooth logo in the case nor use the word bluetooth, should I have to pay for it?

Would developing an Android application making use of bluetooth require any payment or extra cost for using this technology?

Are there any additional costs on Bluetooth Low Energy qualification/certification appart from CE/FCC marking required? I´ve checked this and this questions and it isn´t clear to me yet.

As post in the first question, if we don´t need any marketing/commercial strategy, we could go ahead with the bluetooth low energy certification related to the regulatory marking laws depending on the territory, in our case CE marking, nothing else. Is this correct?


texts: CMOS 4000 series postfix meaning: BCL, BCP, BD

texts:
I am simulating a digital circuit and I need to use a CMOS inverter 4009. There are three of them with different postfixes:

4009BCL
4009BCP
4009BD

What are the differences between BCL and BCP and BD?


texts: When power is lost on an AVR chip (4313 and 8535) why does the mcu run slower?

texts:
I have an AVR circuit for which I have connected its clock-out pin some other circuits external clock and the other pins operate various other things. By using an oscilloscope, I have found that the AVR chip (both attiny4313 or atmega8535) will run at a slower speed after its power source has been disconnected and reconnected.

The chips in the circuit in question are connected to a 20mhz resonator to xtal 1 and xtal 2.  Here is how I recreate the issue:

1) Connect power and ground.

2) burn fuses for external oscilator with clock out

3) press reset button

4) clockout shows 20 MHz on scope, other circuits run at proper speed.

5) Disconnect battery (from the L7805 regulator)

6) Connect battery back to the circuit

7) main chip is now running at around 8 mhz, no nother circuits are running properly.

8) Reburn fuses

9) Works properly at 20 MHz now.

The issue happens with a attiny4313 and an atmega8535.

EDIT: The image is a test circuit that I am using to try and figure this out. It allows me to reproduce the problem.

why is this happening? How do I prevent it from happening?

Additional notes:

Brown out detection at 4.3 V does not fix the issue.

Programmed with an arduino uno as ISP with avr-gcc (latest ubuntu version)


texts: Extension vectors in an array in a VHDL code

texts:
Given :
type data_array is array (integer range 0 to (N- 1))  of std_logic_vector ( ( M-1 ) downto 0);
signal data: data_array     := (others => (others => '0'));

I am going to sum all vector up.

for i in 0 to 3 loop
  adder_sum <= signed(data(4*k)) + signed(data(4*k + 1))+ signed(data(4*k + 2)) ;
end loop;

I need to extend each vector. How to do it?
I have tried:

for i in 0 to N-1 loop
  data (i) <= data(i) (M-l) & data(i) ; -- L additional bits
end loop;