texts: Is it optimized to design same temperature for several heat sink in a power supply?

texts:
I plan to use 5 heatsinks in a two-switch forward converter.

Should I to design same temperature for them or it is optimized to each heat-sink has a special temperature?


texts: DC blocking capacitor value for 2-12GHz?

texts:
I'm working on a simple RF mixer circuit, and having some trouble picking the right DC blocking cap value for 2-12GHz (even higher if possible). Here's the schematic for the front end LNA:

C7 and C9 are what's giving me problems, especially C9 since it's part of the bias-T and I definitely want to get that right so Im not pumping 3.3v into the input of the mixer
What I don't understand is that I've seen some people saying not to go >100pF for any frequencies above 100MHz, but meanwhile this circuit is taken directly from the manufacturer's recommended application circuit in the datasheet and it says to use 100pF which seems high, especially for 15GHz.
Is there some equation I can use to figure out the right value? Or is it not as big of a deal as Im thinking it is?


texts:
I'll preempt this by saying that I'm a software person whose education (unfortunately) didn't even touch on the most basics of hardware or circuits.

I'm attempting to program a PIC16f1709 microchip with a PICkit3 via MPLab X v2.3. The PIC is part of a larger board, but is currently blank. The board in question is a manufactured product, not a dev board, but it does have exposed pins into which I've wired the PICKit, and I'm sure that the pins match up. I'm powering the board with its own power supply. The board doesn't have a pull-up resistor from Vpp/MCLR to Vdd. According to the PICkit User Guide, that resistor is "recommended" (see paragraph 2.4.2).

When I try to program the controller, MPLab warns me first that the target ID is being read as 0x00 rather than the expected value, and then after programming it reports that the instruction at address 0x00 is 0x00 rather than the expected first instruction. My understanding is that this means that the PICkit is not able to communicate with the controller, because it is reading everything as 0x00. I've read that a freshly-erased PIC sets all bytes to one, so even if my code didn't get programmed, it shouldn't be reading zeroes.

Target voltage detected
Target Device ID (0x0) does not match expected Device ID (0x3054).

The following memory area(s) will be programmed:
program memory: start address = 0x0, end address = 0x3f

Device Erased...

Programming...
program memory
Address: 0 Expected Value: 3180 Received Value: 0
Failed to program device

So my question is this: is the pull-up resistor required (as I've read from less "official" sources)? Is the fact that it is missing causing the programmer to be unable to communicate with the controller?


texts: Using two 12V batteries, while simultaneously charging?

texts:
I would like to deepen and clarify the question.

Specifically, I'm planning on using an electric wheelchair to transport equipment for me. Two, 12V 75A batteries are my power source. The wheelchair has two 24V/300W motors.

I'd like to throw a little Honda generator on top, with a battery charger, with two 12V 10A outputs. I'm not looking for "endless" power. Simply greater range, and a little loving care for my batteries.

The charger I've found is 220V/3A. My Generator output is 220V/1000W.

What are my chances of this working?


texts: Second order all-pass filter using a single op-amp

texts:
Is it possible to build an active second order all-pass filter using a single op-amp and no inductors? After Googling it I've found no less than three different circuit topologies, but when simulating them they all have a non-flat frequency response. I've also tried analysing them using some simple Laplace transforms and some algebra, but have failed to get anything similar to the transfer function that a second order all-pass filter should have. This might be because the algebra does get slightly messy, and I don't handle messy algebra very well when tired.

It would be great if such a circuit does exist, as I'm (purely for fun) designing a phasing network to obtain a fairly flat 90 degrees phase difference (quadrature) in the output over a fairly wide range of frequencies, to be used in a phasing SSB receiver for side-band rejection. Currently I'm using a software (called QuadNet) that outputs a phasing network for me, but it uses first order segments, which results in a whole lotta op-amps. The goal is to halve the necessary number of op-amps.

Just for reference; the transfer function of an all-pass filter takes on the following form $$\frac{s^2-As+B}{s^2+As+B}.$$

To be clear, I'm simply looking for a circuit topology that provides this transfer function (2nd order all-pass filter) using a single op-amp and no inductors, and nothing else. Assuming ideal components is totally fine for my purposes.

I'm eagerly awaiting enlightenment!


texts: Can I measure voltage and current at the same time by using two multimeters?

texts: I think the title is revealing. I'm planning to use 2 multi-meters to get a better perspective of my circuits. Is there any drawback in this situation i should be aware?


texts: Using Arduino Mega With lots of strain gauges

texts:
I was looking for a strain gauge shield for an Arduino Mega. I found this link which I found really useful:

http://www.osengr.org/Projects/Load-Cell-Shield/Load-Cell-Shield.html

At the bottom of the web page linked above, the details regarding the circuitry have been made available for downloading.

But I have not built this shield yet as I have bumped into a few problems. I will need to measure the voltage output from around 24 strain gauges (putting them in a half-bridge configuration). So, I was thinking of having only one Wheatstone bridge on the shield and having all the gauges taking turns in interacting with the same bridge. Sorry if this sounds silly, but I was hoping to achieve this using a multiplexer (even though more I think about it, it seems more impossible), so I don't end up making 12 bridges.

Let's say that the previous approach is impossible and I have to make individual bridges per pair of strain gauges. Could I still use a 16-channel MUX like HEF4067B to allow each bridge take turns in signal amplification and analogue to digital conversion through the AD7730 chip? By doing this I want to prevent using an amplifier chip like AD7730 or INA126 for every single bridge.  Also I wanted to use the multiplexer to overcome the limited number of analogue inputs on the Mega.

This way I can use only two analogue pins on the Mega for taking to potentially 32 sensors (16 channels on each analogue pin). Do you think my line of thinking is reasonable or am I really off?

Actually I think this is my main issue at the moment and what I mentioned above are my thought/solutions. I apologize if they are really far-fetched and I really appreciate any help on this matter.


texts: I have a laptop, which comes with an SMPS charger. The laptop charger is a very common type. I know there are some earthing issues in my home. I need to fix that. But SMPS isolate mains from the supply, but when I touch the body of the laptop, it shocks. Another day, I was charging my phone through USB from the laptop and plugged the laptop charger. I own a metal earphone, and that shocked me. I know there's some problem in my home earthing part, but still aren't SMPS meant to be isolated from mains. Then why I'm getting that shock. Why does electricity want to flow through my body if it's floating? Someone, please explain the incident, with reasoning and possible ways to avoid it.


texts: I have a lamp that I really love.Sadly while moving I lost the power adapter. The lamp has 21 leds wired in parallel with a 68 ohm resistor on each. The lamp shows the original power supply to be 6 volts, but no amp rating. I have researched and tried to figure what I need and came up with 350 ma. The lamp works, but some of the leds blink. Can someone give me some advice on this?  thanks J phantom


texts: How to determine number of allowable wires in a crimp wire connector?

texts:
I bought a pack of single-ended crimp-style connectors at a standard hardware store. The data sheet specifies allowable wire configurations, but I am having trouble reading it.

The linked data sheet contains a table (see bottom of post for text description):

However, all the cell values have a dash in them.  For example, the package says Max 5 22 gauge wires, but I don't see a clear way to derive this from the table.  These values exist:

row = 22 wire size, number of wires = 1, column = size 22, value = 4-14
row = 22 wire size, number of wires = 4, column = size 22, value = 1-11

What does the first and last numbers mean? Does the type of wire (stranded/solid) factor into the table?

  Description of the table, in case the image above (or linked
  datasheet) is inaccessible:

  On the left is wire size

  there are row headers such as size 22
  each row header has sub headers such as 1, 2, 3, etc.

  On the top , there is "number of additional wires of one wire type"

  there are column headers such as size 22


texts: Converting negative numbers to hexadecimal number system

texts:
I was programming in 8051 and I faced this problem I had to convert the number -10000 to hexadecimal ( 2 bytes)
the answer is
0D8h = #HIGH(-10000)
 0F0h =LOW (-10000)
but how the answer was found /computed ?


texts:
I purchased an Autofeel 30 inch light bar that has 4 rows of LEDs.

I have seen this bar advertised under a number of different names, but as far as I know it's the only one with 4 rows of LEDs (they all look the same). I have added a picture of the bar, so you may recognize it from that.

It's a cheap Chinese bar, but it works well for the purpose I want it for which is a side flood light.

My problem is it also has 4 modes (white steady, white strobing, yellow steady, yellow strobing). These modes are selected by a time delay, so if the unit is switched off and on in less then 7 seconds, it will select the next mode.

If switched off and on again after more then 7 seconds, it will go back to steady white.

I have it rigged up to sync with my high beam and it's proving to be a major pain in the rear (or front in this case).

My first thoughts (see my previous question) were to build a time delay circuit that prevents the unit coming on in less then 7 seconds after it was switched off and I think I have that sorted. However one of the contributors mentioned it would be better to directly modify the light bar.

I have seen it advertised with an extra wire which you use to manually select the mode (that's what I thought I was buying) so I guess it's possible to modify the bar to make it work like that.

So my question is, which is a long shot, I know: Does anyone have any information, circuit, advice to modify the light bar so it only works on white steady?

I have written to the manufacturers and the supplies but got nothing back, except how to use it with the time delay to switch the mode.


texts: Microcontroller - potential damage to IO pin

texts:
I'm revisiting a design I made.

The circuit is powered by 24V with polarity protection.

I placed a power loss detection before the polarity protection:

In case the power pins were replaced, the 3v3 zener diode will have forward voltage of ~1V.

will this pin go through R32 to the "unpowered microcontroller" and destroy its IO pin?

The absolute maximum is -0.3V in the mcu:

It's only 100uA limited by R32, but I can't be sure.

Is there such detailed information about the IO pin?


texts:
I’m building a circuit around an LT1172 to deliver 0-300 V from a USB charged LiPo cell. I’ve included the circuit.

I’m using an EPCOS EFD20 former with E87 cores (0.3 mm gap).
If I just have one of the output windings the circuit works like a charm, with an arbitrary 200 turns on a single secondary I get a solid 140 V into a 45 K resistor which together with the 100 K feedback pot works out at just over 0.6 W and holds line regulation between 3 V and 4.2 V input and load regulation doesn’t budge, efficacy is 65 % which I think isn’t too shabby, it also adjusts from 300 V down to 1.25 V, with a 2.4 V Zener in series with the output I can get 0-300 V, I couldn’t ask for more.
Now the issue is when I wind the second secondary everything goes belly up. Both windings end up going down to 84 V, I can tweak these back up to 130 V however I loose regulation and when I connect the two stacked outputs together the total voltage collapses further and the input current drops.
Originally I used an online flyback calculator and entered the following:
100 kHz
Eff  60%
Al   0.25
Vin     3 V
Vout1   150 V
Iout2   0.0022 A
Vout2   150 V
Iout2   0.0022 A
This resulted in:
Lp  19 uH
Np  8.74 (9)
Ns1 659
Ns2 659
The 9 primary turns didn’t seem to put enough energy into the core and even a single 659 turns of secondary just killed the circuit, so I wound 19 turns on the primary (48 uH) and took a punt on 200 turns for the secondary which worked perfectly as mentioned.
Obviously the high number of turns on the secondary is causing the issue but I seem to have hit a brick wall and can’t get anywhere near my goal of 300 V.
I’ve built a few of these 300 V circuits before but used a XP A03P-12 which are very expensive and need a 12 V supply as well as not being adjustable.
Anyone know what I’m doing wrong?
edit. The core in the picture is separated, this is not how it was being used, I found by separating the cores I could get another 10 V of output.


texts:
How can I calculate the effect of accuracy on voltage for a 4-20 mA current loop for a 500 Ohm 0.1 % shunt resistor?

How much is the accuracy affected by this resistor, I mean.


texts: How to calculate the maximum current that a wire can handle?

texts:
What are the methods that manufactures used to do so ?
What is the formula used if there is a one to do so?


texts: Optimize signal return path with decoupling capacitors in a two layer board

texts:
I'm designing a pretty complex two layer board - I should really go for a 4 layer one, but that's not the point here. I'm done with component placing and routing and I'm doing the finishing touches such as making sure the ground planes cover most of the board and are well stitched together (a.k.a ground gridding).

In certain areas, I have signal traces (e.g. SPI) layed out over a ground plane, then a power trace (14V), then another ground plane. There is no way I can move this power trace out of the way, so I thought I could let the signal return currents go through it by having some decoupling capacitors (100nF) between the power trace and ground planes, right under my signal traces.

Here's an image of what I'm thinking:

Is this a good idea to reduce the signal loop area and control EMI?


texts: Can I use two Power Source to Switch with a Relay like this?

texts:
I'm Planning to switch between two power sources with a Arduino like below diagram.

what I'm going to do is monitor AC power failure with a sensor and then once AC power failed switch the Relay to Battery source.

My question is, Connecting two ground wires from DC adapter and Battery Ground will cause any trouble?


texts: Dual Digital Pot With Different Op amps & Layout

texts:
I'm using a dual digital pot IC controlled with an SPI interface.  Each pot goes to a different op amp on the pcb to calibrate two different voltages.  Since both pots are in the same package, how big a deal is it if the pots are far from the op amp feedback loops?  Typically, the amp resistors should be as close as possible to the amp to reduce noise.  The voltages ultimately feed into 12-bit ADCs, so with the resolution being relatively low, can I get away with this as is?

Also, how do the SPI lines affect the DC analog readings if at all?  If I keep the digital traces away from the analog values with a ground pour in between will that suffice, or should they be isolated in some other manner?

I'm looking to get the most accurate/stable reading possible.  Currently going with a four layer pcb, but may have to reduce it to two.

Thanks

Edit: images added


texts: closing a circuit programatically if ground can't be interrupted

texts:
I need to be able to "push" a button on a control panel using python and an arduino board.

My problem here is that the button in question, when depressed, sends 16 vdc to an outgoing wire that disappears into the bowels of a very large machine. Isolating the ground that completes the button's circuit is infeasible at best although it has continuity to the machine's frame so it could still be joined to an arduino's ground.

This is a problem for me because, with my limited knowledge of electronics, I'm only familiar with methods involving closing the ground using an NPN transistor or an optocoupler connected to an arduino's pin.

If I can share the ground but have no way of turning it off is it still possible to connect the break in the positive wire just as the button does manually with either NPN/PNP transistors, an optocoupler or a combination of both?

I ask because I have several boxes with dozens of types of these but no suitable relays.

Not expecting a schematic but if someone could fill in some of the holes in my knowledge or maybe point me to some appropriate Google search terms I'd be very appreciative.


texts: Feedback regarding isolation practices on a 5V/Mains PCB

texts:
I am currently designing a PCB for a project including PID-control of a heater. The heater runs on mains (220V) and is controlled using zero-crossing switching to regulate the power and minimize EMI and THD.
I already designed multiple PCBs , also ones with mains, but never low and high voltages on the same board. By now I have e prototype-design, where I made the following safety considerations:

strict separation (HV,leftside - LV, right side, see line on top silk layer)
connection HV-LV only via optotransistor/-triac (U1 and U2) and a switching converter U6 including a isolation transformer
further protection with MOV(R6), fuse (F1) and use of a snubberless triac Q1
copper planes of LV part start only after the last everything is converted to LV

Since I do not really have any space constraints I designed everythig with a lot of clearence (grid is 1mm) and used 2mm traces for the AC-powerlines. The PCB is then mounted in a metal box connected to PE or in one out of isolation material.
My main concern is that there are three JST plugs on the LV side (U4,7,8) that connect to rotary encoders, screens,etc, that are accessible to the user. While I am confident about the isolation on the PCB I still wanted to get second takes on the design, especially regarding the connections to the user-accesible features. Are there additional considerations to make in this case?

Any feedback regarding any part of the design is appreciated!


texts:
Can 5V be applied to 3.3V "5V tolerant" ADC inputs for indefinite durations? I'm looking at hardware failure modes, I know the ADC value will be clamped at 3.3V.

I just would like to know if I should generally be cautious with 5V tolerance stated in datasheets in case some implementations are actually non-permanent protections.

[Edited out the example of the ARM LPC1768]


texts:
I have build three Boards with the ESP-07 Module.
These should function as water alarms.
I use a modification of the project: http://esp8266-server.de/Wassermelder.html#
See schematic under "Wassermelder mit ESP-07 / ESP-12".
As soon as water reaches the pins + 3V / CH_PD, the ESP wakes up from the sleep state and logs on to my website. This works fine.

I have removed the led to get low-current-mode.

When I put the circuit into operation, the CH_PD pin is still low. I have measured the power consumption but i have different behavior on my three boards:

Power - around 0,03mA - Expected behavior
Power - around 1-2mA - short time ch_pd on high (Bord wakes) - ch_pd low - around 0,05mA
Power - around 1-2mA - short time ch_pd on high (Bord wakes) - ch_pd low - around 1-2mA - sometimes i get it to about 0,1mA.
All uses the same Sketch and the same wiring. Have i problems with a floating input? Or have i different boards? What else could I have done wrong? I cant find any problems with my wiring


texts: Linear Circuit Analysis: Source Transformation of DC Network

texts:
The 1st (upper) picture is the given problem. The 2nd (lower) picture is my attemps to the solution.
I neglected the middle resistor in bridge circuit, resistor in parallel with voltage source, and resistor in series with current source. But now I'm stuck, any hint?


texts:
I have an AC to DC power supply (specifically the Mean Well RS-25-48 datasheet). When the power supply is not being used, I want it disconnected from the AC mains.

I've thinking about using a SSR-10DA to achieve the above, but I don't know if it is compatible with this type of load. Specifically I don't know how the minimum current specification of the SSR will affect the operation of the power supply.


texts:
I know it's 2014 and you can get an MP3 player and 40 bazillion terabytes on a microscopic chip.  But I want to build a 6502 based retro computer and, in a perfect world, I would order up about 200 SID chips.
Anyway, are there any mass produced audio chips these days that closely resemble the remarkable chiptunes of the 80's?
I've ordered four AY-3-8912's off eBay but I'd like to find something similar but still in production.
Oh, gutting vintage computers is out of the question.  I restore them.  Not gut them.  ;-)
EDIT
I wanted to post a followup to those who are curious.  Finding old vintage audio chips on eBay isn't too difficult.  But, obviously, not for any kind of mass production.
Anyway, I have found an alternative using the Propeller chip from Parallax.  Using that microcontroller, you can emulate with high accuracy the SID, AY-3-8910 and SN76489 chips.  Each emulated chip resides in one cog (from 8).
SIDcog v1.3
SNEcog v0.6
AYcog v0.8


texts: Do low-ESR ceramic capacitors in the uF-range exist?

texts:
I am designing a power supply for my board and plan to use an isolated, regulated DC-DC converter. This converter from Murata fits the bill, but the datasheet doesn't provide any guidance on input or output caps.

So I looked at competitors and found this one from TI which is a more feature-rich version of what I'm using. The data sheet shows this example circuit:

The note on the input cap says:

  \$ C_{IN} = 2.2\mu F \$ for 5-V input devices... Low ESR, ceramic
  capacitors are required.

Is there a typo here? On Digi-Key (search URL), the highest-value they have for low-ESR ceramic caps are 3.3nF, and they cost $43 USD each. What gives?


texts: Is it OK to use switching regulators to charge mobile phones (and such)?

texts:
I had several issues with car usb adapters (dc-dc step-down regulators), and I'd like to make one myself.

Issues:

Nokia cell phone refusing to charge
Motorola phone power supply circuitry fried
Insufficient current

The first thing I'd like to know is whether it's fine to use a switching regulator.

My understanding is that the output will be a square wave signal, am
I right?
Will the cell phones like that?
Will the ripples and resonance in the signal will a further problem?
If I employ a regulator such as the TSR 1-2450, should I
add other components to filter the input and clean the output or is
it fine to use it just by itself?
Am I better off with a linear regulator?

UPDATE:

I tried using a LM2576T-5 with the standard configuration:

It worked great! Then I added the suppression circuitry suggested by @tcrosley, but with a couple changes:

I did NOT double the 100 uF capacitor at the beginning of the first circuit and that at the end of the second.
Since I couldn't find a 1.5KE18A, I used a 1.5KE15A, which works at 12.8V, so I suppose it should be fine.
The 1N4001 wasn't good for me, since it limits current to just 1A. I used one of the 1N5822 I already had, comforted by what I found here.

This resulted in inverted polarity (!!) on the output of the LM2576, which ceased to work shortly afterwards (I didn't cut the power, because it seemed to work somehow, so I was measuring voltages when it died).
I triple checked my soldering work, but all seems in order (well, quite ugly actually!, but correct).
I really can't figure out what's the problem. Maybe I'll just get another LM2576 and remove the suppression circuitry.

The power supply for the testing was a 12V, switching (common PC PSU).

UPDATE 2:
The IC is still good and the circuit is finally working. Turns out that the inverted polarity was my fault. I connected 2 usb sockets to the leads, but I had the pin-out upside down! Since the usb socket casing is shortened to pin 4 (ground), and I thought that was pin 1 (Vcc), I ended up this circuit:

Now I fixed it, and I will try again with the suppression circuit. I'll use at least the TVS diode.

UPDATE 3:
It seems like I had this all wrong from the start.
I added the suppression circuitry, checked that all was working and mounted the thing on the car. And surprise surprise, it started smelling after a few minutes! While in the LM2576 datasheet it is written that there's no need for a heat sink, the reality is that it gets really, really hot after just a few minutes of phone charging :(
Note how it melted the inductance nearby!
Now, in order to fit a heat sink, I'll have to do a new board...

UPDATE 4:
take 3, finally working properly. thank you all!


texts: Creating a vibration device based on bass in audio

texts:
First, I'll admit that I haven't done any real electrical engineering in years so I'm quite rusty. But here's a fun project to contemplate:

I'm building a device that "rumbles" with the bass in the audio, to increase immersion. One similar device is this Basslet. It's a "silent haptic subwoofer" if you will.

Current concept:

USB or 3.5mm jack audio input from PC
Some low pass filtering, ideally configurable. Was hoping to use an Arduino but not sure if it's powerful enough... Google searches didn't help.
Output processed signal to a vibration actuator (motor? linear?)

Desired result: a box that vibrates with the lowest thumps in music and movie audio.

Any tips on where to look/start? Should be a fun project!


texts: Output resistance of CE amplifier small signal model

texts:
I was studying input/output impedance of CE amplifier small signal model and I wanted to know why the output impedance (looking from the collector) is just Rc in parallel with dynamic output resistance of the transistor (ro).

When calculating output impedance why are RB and rbe neglected? and also is the current through Rc just Ic if so why ?


texts: How can I calculate max, min frequency between FF to FF in RTL design?

texts:
I am trying to review regarding RTL design.
The RTL design as follows

--FF---Comb----FF----FF----

And each FF have same configure like this

setup 1ns
hold  1ns
output 0.5ns

Also, the Comb(combinational logic) have configueblike this
propagation time 5ns. If the clock skew is -1 or 0, How can I calculate what is the minimun and maximum frequency of operation of this circuit ?


texts: Balance charging and protecting 4s LiPO battery pack

texts:
I'm planning to use a 4s 18650 LiPo pack to power a portable speaker and I'd like to include a charging circuit, so I don't rely on an external balance charger. I currently have it hooked up to this HX-4S-A01 protection board, which apparently lacks balancing features.

Am I fine, if i just add such a balacing module and hook it up to a 16,8V Power Supply, or do I need a different module e.g. to limit current?

Would this module alone do the job of protecting, balancing and charging the batteries?

I'm a bit lost in the different types of protection and I appreciate any help.


texts: Help with resistor in gain and filter op-amps circuit

texts:
I'm designing a piezo preamp with high-pass filter using two preamps. The first one amplifies the signal, while the second one filters it (and some little extra gain). See schematic:

simulate this circuit – Schematic created using CircuitLab

My question is about R4. Is it needed? What value should it have? I read in one answer, that op-amps don't like to drive capacitors. What happens with or without R4? Another question, would I be able to reduce this to one op-amp if my input is a piezo? Or do I need the first one to buffer the high-impedance piezo signal as I've done now?


texts: Variable voltage signal importing and procesing using computer in real time

texts:
I am working on a project where I need to import an analogue signal into a computer for real time processing. Signal strength is about 2-10V.
I found this solution where it is possible to use the microphone port of the computer and observe signal like an oscilloscope, but I don't know what software to use for signal processing.
The best option is to use USB port for importing signal, I have found some expensive solutions for that, but instead I want to solder something up. So any idea about that?


texts: Power button does not work unless I short power pin to ground (then the power button works normally afterward)

texts:
The title might be confusing but I am confused as well, This is an old sony ta-808m amplifier.
initially, the issue was a broken power button I have replaced it with a new power button and I can confirm that the power button itself is working (continuity mode using a tester, not by powering on the circuit. Even with the circuit powered on it does work, shorting pin 5 pwr to ground BUT IT STILL DOESNT WANT TO TURN ON) it's just idling in standby mode.
Now my main issue is this I've tested every resistor, transistor, capacitors, and connection paths. All are in the right value.
the only way this amp powers on properly is by using a piece of metal (or any wire) to jump pin 5 to ground. After doing that everything works flawlessly and as intended (and makes the power button work properly as well as if there is no issue.)
the problem goes back when you unplug the amplifier.
you will need to short pin 5 to ground again manually in order to make everything work properly again.
Edit: I even tried replacing the old wires with new ones and it's still the same.
Did I miss something in the circuit that the amplifier won't work (the power button) after unplugging it and plugging it again?


texts: What are these wires on single-sided PCBs?

texts:
I have a few questions about this PCB, namely the wires across the visible side:

I am new to electronics. Would these wires be considered a "trace", "jump", a "via", or something else entirely?
How would this be illustrated on a schematic to indicate that it is an actual wire and not part of the etching?
If one were to purchase this kind of solid wire, what would its gauge be, its material, and how would I search for it so that I exclude results with shielding?
Are there any issues with running wires like this without shielding? Such as electrical interference.

Other questions, not necessary for a complete answer:

Unless I am mistaken, these do not appear to be hand-made due do their exactness and how straight they are. How does a machine place these? Or are they pre-bent, placed, and then sent through a wave solder machine?
When would this method still used today? Or is it something that is an artifact of single-layer boards where one would otherwise use a through-hole via and traces on the other side?


texts:
I have a bad 350v 2 uf fan capacitor. I managed to find a 400v 6.3uf cap in my locality, would this work instead of the 2uf one?
Thanks.


texts: Difference between logical and virtual addresses

texts:
Today I heard that a:

DMA-controller is mapping/converting logical addresses (from I/O-Mapping) to physical addresses
MMU-controller is mapping/converting virtual addresses to physical addresses

So now I'm really confused! What is the difference between logical and virtual addresses? Why do we need that new type of address (logical address)?


texts:
I am designing a shift register. It has a control signal called RD which is asynchronous (so cant use it inside the procedural block), the whole point is my n-1 bit shift register is value of the input if RD ==1 or else it has high impedance; I am not sure how to write the assign the high impedance value because my n bit is a parameter so I cant define the no of bits.

inout [n-1:0] Data;
input RD;

reg [n-1:0] register;  //my register

Example:  Data = (RD==1'b1)? [n-1:0] register: 'z ;

its giving me a error. How can I define that if RD is 1 then I need to see what is there inside the register and if its 0 then, it should be high impedance. Can anyone help?


texts: Setting Pulldown on the PMOD Pins (Nexys A7)

texts:
Ive created a keypad scanning project with Verilog. The waveform works great! But it did not work in practice. Through troubleshooting I found that it will work if I add external pulldown resistors to the pins im using as inputs. Ive read that its possible within Verilog to set a pin to pulldown. However im not finding great information on how to implement it. Through docs it looks like it should be done by the line set_property PULLDOWN TRUE [get_ports outputport], however my xdc file seems to be formatted different and I have been unable to figure it out. So, how do I set PMOD pins to pulldown with my XDC file?
XDC PMOD lines:
set_property -dict { PACKAGE_PIN D17   IOSTANDARD LVCMOS33 } [get_ports { column[1] }]; #IO_L16N_T2_A27_15 Sch=ja[7]
set_property -dict { PACKAGE_PIN E17   IOSTANDARD LVCMOS33 } [get_ports { column[2] }]; #IO_L16P_T2_A28_15 Sch=ja[8]
set_property -dict { PACKAGE_PIN F18   IOSTANDARD LVCMOS33 } [get_ports { column[3] }]; #IO_L22N_T3_A16_15 Sch=ja[9]
set_property -dict { PACKAGE_PIN G18   IOSTANDARD LVCMOS33 } [get_ports { column[4] }]; #IO_L22P_T3_A17_15 Sch=ja[10]


texts: BJT base connected to ground and still operates?

texts: When in university I used to get confused how a transistor (NPN) can draw current from ground. I'm now studying power amplifiers and again, this same configuration appears. How does Ir draw current from seemingly nothing/ground?


texts: IP2 1dB compression point representation and formula

texts:
I'm trying to calculate the 1dB compression point in a second order interception. I did find many examples using third order, however, for a second order, I couldn't find much.

In Matlab I could find the interception point using the following code:

% Parameters
a1=5; a2=4;
G1=20*log10(a1);G2=10*log10(a2^2/2);

% Equations
Pi=-10:0.1:10;
Po=G1+Pi;
P2=G2+2*Pi;

% Interception Point (3)
IPi=(G1-G2);
IPo=G1+IPi;

How can I get the 1dB compression point (referenced to output) using this code? And the representation of the gain.


texts: Detecting low currents in high current industrial environment

texts:
I would like to detect if a current flows in a 3-phase industrial environment where currents can go up to 120A. Anyway, for me is only important information current is flowing/current is not flowing. The threshold should be somewhere about 0.5A - 1A. I excluded shunt and current transformer solutions from consideration because I cant put shunt anuwhere (but I also think it is not quite applicable for such high current environments) and the later seems to be more expensive than solutions with Hall-effect sensor which I would like to consider here. In this question I would like to consult you about the principles in order to choose the one that fits the best my application.

Is there a Hall-effect sensor which is able to provide a digital output based on the absolute value of the magnetic field? I checked various types of Hall-effect sensors, bipolar, unipolar and omnipolar. The closest to what I want is unipolar but none of unipolar sensors can actually treat south and north poles in the same way. By this I mean, that threshold should be for +- x T. Using such an element I believe I would minimize my BOM.

Since all three phases are in vicinity of each other, how sensitive might be using Hall sensors in such environments in terms of flux cancelations?

Would it be possible to implement this without a ferrite ring for concentrating magnetic flux? My calculations give in the worst case, 3mm away from the conductor about 0.5G (2/3e-4 T).

Is there any other interesting way of doing this that I missed completely?


texts: Electret microphone amplifer for general aviation

texts:
I'm attempting to create a converter box that allows the use of a standard electret mic and earphones as a headset for general aviation. The headset is relatively straight forward, just use an audio transformer to get a decent impedance match (~150 Ohm for the avionics output vs 8 Ohm for the headset). The mic is a little more difficult. In order to be compatible with WW2 era carbon mics, the avionics expect an input of ~0.5-1V and ~400 Ohm impedance. The avionics supply phantom power (or in the case of an actual carbon mic, DC bias). The actual voltage supplied seems to vary quite a bit, but 5-7 VDC seems to be typical. I've thrown together the above circuit to amplify the electret output and hopefully get the impedance close based on this answer, but I'm an ME by training and my analog circuit design skills are a bit rusty so I wanted to get some feedback from the community. My thought process is to combine the inverting amplifier with a voltage divider to get the output voltage and current into the desired range. I'm not sure that C2 is necessary since the audio+ line is already carrying a DC offset, but I figured it couldn't hurt. Is this approach at least on the right track? Thanks in advance!

EDIT:
I haven't had time to pick up the components yet, but I was in the plane today and decided to try the mic as is with no additional circuitry. The mic was only faintly audible, which is about what I expected. Based on this I'm planning to try out Andrew's circuit once I get the parts. I'm also thinking of just replicating the electret's internal amplifier by hooking up a jfet as a backup plan.

EDIT 2:
I was able to test Andy's circuit this afternoon and it worked well. The only change I made was to reduce the 100 ohm resistor to 10 ohms to increase the gain slightly.


texts: I want to design pfc boost converter using uc3854 but I am not getting its simulation model also on texas TINA ti library. Where can I simulate it?


texts: Why does an analog oscilloscope have a frequency number written on it?

texts: So in our lab, we are working with an oscilloscope, an Analog to be precise. It is the Tektronix 2205. My question is if it is analog, then why would it have "20 MHz" written on its box.


texts:
I'm collected some input leakage information for I/O libraries. Most vendors and datasheets give a maximum value +/-1uA for the input leakage information (see below an example):

This value is higher than the value reported on the liberty file that makes part of the simulation/characterization files provided by I/O cell vendors.
What considerations are taken and how it is characterized?

For my application this value is prohibitively large, due the chip will be supplied by a coin battery and should be ensured a long term operation. In the worst case my chip would consume Number of I/Os times 1uA.


texts:
I'm trying to drive a Peltier cell. The driver must allow both operation modes (cold/hot). To achieve this i'm using filtered 3.3V 100KHz PWM from a microcontroller to drive an H-Bridge (as far as i've read on the internet filtering PWM signals coming out from the bridge with an LC filter is useful for efficiency problems). The Peltier cell is a 70W 12V module.

This is the H-Bridge/Filter section:

This is the IR2110, bridge driver for A and B side:

I'd like to know if this circuit will likely work or if there are any mistakes in components maximum ratings (like free-wheeling diodes) or other stuff that can create magic white smoke.

Feel free to ask anything.

Thank you


texts: How does the HD44780 LCD work at the low level?

texts:
I'm not asking for a driver specifically, but how exactly it works.

I looked up the 2 chips that were in it. HD44780A00 and HD66100F to be exact. I'm assuming one is a display driver? And the other is a segment driver?

I guess I'm looking to learn how, in this most basic terms, for instance, a pixel or a character is put on the screen.

I know how to use it with libraries and such. That's simple (just follow the instructions). But I want to understand what's going on.

I looked at the instruction set here. But is that just for the HD44780A00 or HD661001F? I guess I'm confused at what this instruction set is or what is it for.
I guess what I'm asking is: what exactly is the process for sending a single pixel and how exactly does that work.

It might be too complicated and if it is, that's cool. I'm just trying to figure out how it works at the low level.


texts: USB hub with 12V 5A power adapter – how can it convert the power into more amps?

texts: I've found an USB 3.0 hub that has 12V 5A power adapter. USB 3.0 specification says that ports should support 0.9 A. The hub has 10 ports. Users say that it's very stable and suggest that in order to provide 9A in total the hub converts 12V to 5V with larger current. But is it possible without a transformer? Could they use some small transformer for each of the ports?


texts:
I need a controllable frequency for use in a radio transceiver with a range of 3–50MHz (i.e., 80m–6m). The frequency needs to be selectable using a microcontroller. Because chips like the Si5351 tend to give birdies, I want to use a DDS. However, that would mean a >100MHz crystal oscillator since as far as I know all DDS chips require an at least twice faster input signal. It's not so easy to get a >100MHz crystal oscillator, and I want to use common parts as much as possible.

Would it be feasible to use a lower frequency crystal oscillator and a PLL to scale it up? Specifically, I'm thinking about the ADF4002 PLL with the AD9913 DDS. Or are there other options that I'm missing?


texts: Voltage drop on relay coil while driving relay using Darlington Arrays

texts:
I am using Wemos D1 mini and trying to use ULN2083A Darlington Arrays to drive SRD-05VDC-SL-C relay. The relay does work properly when the circuit is connected as attached schematic.

The Darlington array (ULN2803A) would decrease the load voltage by about 1 volt across the internal transistor. If I have a 5V supply connect to the array and wish to use it to drive a 5v relay, the coil would end up receiving ~4 volt when it is activated. Is it acceptable? How would this affect on the relay?

I also tried the same thing to drive SRD-12VDC-SL-C relay with the 12v supply. The voltage would drop to about 11v as well. The relay does work but I have the same question, is it acceptable?

If the both scenarios are acceptable, which setup is preferable? Also, the circuit seems too simple to me, am I missing anything to improve it?

Edit: adding the datasheet of the relays


texts:
A thermocouple amplifier outputs a voltage range of 1.2V to 8.8V for the temperature range -260C till 1380C when using a K-type thermocouple.

The formula used to determinte the measured temperature is Ttc = ((Vout - 2.05) * 0.005)°C

I am thinking of using two 1K ohm to divide the output voltage by 2 so as to fit within Arduino's max input voltage of 5V.]

Question: For maximum accuracy when determining the temperature, is 1K ohm resistors suitable, or should we increase/decrease their resistance?

Link to product


texts: Can anyone please explain how do I get this variation of Ix vs Vx curve?How do I determine whether the current will be in positive region or negetive?


texts: Design considerations for large ratio step-down transformation

texts:
What are the design considerations for a system in which a high voltage and current DC soliton pulse (approximately 50kJ at 45kV over 100ms) from a capacitor bank or PFN must be stepped down to a low voltage DC pulse (say 5v)?
The source is an ex-military HV capacitor bank. I would like to step it down as far as possible for safety reasons, and since I am trying to use Joule heating to sinter alloys of mostly rare earths (powder metallurgy).
Would the best solution be to use a monolithic transformer for this purpose, or are there better ways to do it? I imagine that very hefty, low-resistance conductors would need to be used on both ends, with an improbable number of turns on the primary.
In practical terms, I know that this sort of transformation is done in systems used for capacitor discharge sintering, pulse welding, or possibly in high-energy physics experimentation. How is this typically accomplished in such scenarios?


texts: What control scheme do ESCs for RC planes use?

texts:
I have just built an electric skateboard based on a Hobbyking 50A ESC, controlling a 400Kv outrunner-type brushless motor. The skateboard requires a little nudge at the beginning to run regardless of the speed setpoint, otherwise it struggles and vibrates. This is not an issue of torque capability, as it can carry me up a slope without issue once it has non-zero speed.

I'm starting to think, in spite of discussions I find on the web saying these sorts of controllers use sensorless position feedback algorithms, that the stator rotating field is set to rotate at a given speed (i.e. fixed frequency) regardless of the rotor position - resulting in very little torque when driving very high load inertia at zero speed. I was expecting some kind of closed loop control of the stator field with respect to the rotor field (90°), wouldn't you?


texts: Continous liquid level measurement loop connection device

texts: I have 4-20mA loop device for measuring liquid levels. It was working well until I connected a motor (heavy load) to the same outlet(120Vac). I have this device ON and as soon as motor turns ON the output of the device starts flickering. I believe it is noise from the motor. How can I prevent this from happening?


texts: Clarification on R, I, and J type Instruction formats in MIPS

texts:
I would like some clarification on some concepts of register types, to know if I understand it correctly.

If I had a 32-bit CPU.

Would that mean that the max number of operations that can be executed by the CPU be: $$3\times2^{6} = 192$$

Also, would the number of registers in the CPU be:$$2^{5} = 32$$

Which would then make the main memory be: $$32 \times 4bits = 64 bits = 8bytes$$

Finally, the maximum size of the target address of the J-type would be:$$2^{26} $$


texts:
Hi guys i just learned a new topic last week and i was unsure on these questions.
Does anyone know how to determine in the diagram if it's forward-biased or reverse-biased?
How can i calculate the diode current in the diagram. Thanks

Voltage at X= 10v

Voltage from X to Z

10v-(-20v) = 30v

Voltage at Vxy= 10k/20k x 30v = 15v

voltage at Y= 10v-15v= -5v


texts:
I'm needing to create a 4 bit, 16 input multiplexer. I know I could describe this as a long list of S => when "0000" etc.. but I think that's not very clean, and I'd like to opt for a generic n-bit multiplexer so I can reuse it later for more inputs or whatever.

How would you do this?


texts: Reading industrial magnetic length sensor (DRO)

texts:
My brother broke his LCD display on his saw, it is a simple display put on conductive silicon strip showing numbers and some status icons.

They priced the replacement for about 500$, which is kind of lot in our country.

So i thought that since the only important function is to measure length, that i take the sensor connected to the display, find the documentation and use it with arduino.
But the documentation cant be found because it is custom made sensor by the company. It has five wires and the display was powered by one AAA battery.

Before i dive into debugging with logic probe, did anyone used that sensor in his project?

Thanks, im also uploading images of sensor and PCB.


texts: TI SN65HVD75 RS485 is not working while transmitting

texts:
Now I am doing a project with TI SN65HVD75 RS485 and nrf52832.
The project is converting RS485 to BLE or BLE to RS485.
I succeeded converting RS485 to BLE. If other RS485 device sends datas to my device then my device will pass them to BLE.

But I can't transmit datas from BLE to other RS485 device through my device.

The circuit of my device is here.

Please, see SN65HVD75DGK part.
I use GPIOs of nrf52832 like following.

R : P0.14
RE, DE : P0.15
D : P0.16

I set R as pull-up by programming.
Before send datas from my device to other RS485 device, I set RE, DE as HIGH. But the datas are not passing.
I suspected nrf52832, so I tested TI SN65HVD75 RS485 with Arduino Due.
But also datas from my device to other RS485 device are not passing with Arduino Due.

I think that I did wrong with TI SN65HVD75 RS485. But I don't know what it was.


texts: Connector for splitting GND and VCC to six servos

texts:
I have one ground wire and one voltage wire that needs to be split into six separate pieces so I can connect each piece to a servos voltage an ground pins(which are male).

I basically need a wire jumper(female) that I put one ground or power pin into, then its outputs (female or male doesn't matter) go into the servos.

Note: Its output doesn't have to be six, but as long as the input to the wire jumper is one. I did research but found nothing

Servo stall current is 2.5 A at 6 V. During operation it is 1 A. Servos operate from a supply voltage from 4.8 V to 6 V.


texts:
I am looking for the pinout on a hantronix HDM24216L-2-L3ES
24x1 LCD. I found the datasheet:
http://www.hantronix.com/files/data/1278557021char-comm.pdf
but I cant determine what the pinout is. Can someone help me find the pinout for this device?


texts: Working out ICopy from a current mirror [Mosfet]

texts:
I'm trying to solve for \$I_{copy}\$, but I've looked around on the internet and cannot find an explanation. However, I know the formula:

\$ I_{copy} =\frac{I_{REF} * W_1/L_1}{W_{REF}/L_{REF}}\$

but don't understand how to work this out from the circuit diagram.

Attached is an image explanation my problem. Answer for:

The circuit on the left: \$I_{copy}=\frac{2}{8I_{REF}}\$
The circuit on the right:  \$I_{copy}= 7I_{REF}\$


texts:
how to model igbt from the APT150GN120J datasheet.
SHEET 1 880 680
WIRE 160 64 160 -32
WIRE 112 144 48 144
WIRE 336 160 160 160
FLAG 48 224 0
FLAG 160 -112 0
FLAG 336 240 0
SYMBOL Misc\\NIGBT 112 64 R0
SYMATTR InstName Z1
SYMBOL voltage 48 128 R0
WINDOW 3 -104 149 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value PULSE(0 1 0 0 0 12.5e-3 25e-3)
SYMBOL voltage 160 -16 R180
WINDOW 0 24 96 Left 2
WINDOW 3 24 16 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 25
SYMBOL res 320 144 R0
SYMATTR InstName R1
SYMATTR Value 10
TEXT 256 64 Left 2 !Z1 C G E M1 [1e-4] [off] [temp=25]
TEXT 256 88 Left 2 !.model M1 NIGBT
TEXT -58 298 Left 2 !.tran 20m

using this coomands
Zxxx C G E MNAME [area] [m=] [off] [temp=]
.model MNAME NIGBT
how to obtain this values from above datasheet to model the igbt


texts: What are the physical mechanisms of core loss, and how can they be minimized?

texts: Suppose you have an inductor in a boost converter. The core gets hot. Why? What are the physical mechanisms that cause core loss? Eddy currents? Magnetic domains flipping? Coupling to materials outside the core? Others? How can these losses be minimized?


texts: Understanding the thermal images of planar pcb coils

texts:
Why is only the first turn in the coil hotter compared to other two turns?

In this, only the turns of the top part seem to be hotter compared to the bottom.

Current through the coils is 2 A. It is connected to a half-bridge operating in buck mode at 1 MHz.

I don't know if I am making any mistakes in capturing the images, but I expected a more uniform distribution of the heat.

Here are some details about the second coil:

Top Layer

Bottom Layer

and Coil connected to the board

The board is FR4 material and turns are copper.


texts: What electric field strength in the range 50MHz to 3.5GHz should be considered "natural"?

texts:
If we were to measure the electric field strength of the earth's surface in the range 50MHz to 3.5GHz (in the absence of any man-made transmitter), what value should be considered "natural"?

The next paragraph was in the original formulation of the question, but it is useless and is left here only to make sense of the comments: I read that the electric field should be about 150 Volts per meter, but I do not understand what range this refers to.  (Or maybe I do not understand what electric fields are.)  I measured it in the above range (with a Tenmars 195) and I got much smaller values.


texts: How to Amplify Thermocouples (and DC sensors between 1mV and 1µV DC)?

texts:
This is a bad idea, I know

Here's what I know about amplifying really tiny DC voltages:

it's impractical to build your own for production
there's going to be noise
the signal is relative to the cold junction temperature
it would be easier with an ASIC than using basic components
most op amps aren't rail-to-rail (can't go to 0)

These are all acceptable to me. I want to learn how to do it anyway.

Background

I've just started self-teaching and I thought that measuring the actual temperature in my toaster oven with what I have laying around (batteries, resistors, thermocouples, resistors, and op amps) would be a fairly simple and easy first project to design myself. Maybe I'm wrong, but I believe  it's possible and I want to learn how.

Where I've been

I was able to measure between 0.2mV and 0.4mV while holding the K Type (41µV/˚C) thermocouple with my finger (37˚C supposedly) using my multimeter. That checks out: ~0.5mV = 41µV * (37 - 23).

Well, I can't read that in on 0-5v analog input...

At first I thought that perhaps I could use series of transistors, but since there's no current (and the voltage is well below the minimum necessary), that was a bust.

I remembered reading and hearing about op amps, so I thought perhaps that might be the right tool for the job. I watched Dave Jone's excellent EEVblog #600 - OpAmps Tutorial - What is an Operational Amplifier? and that I'd give it a try.

The local university has a plentiful supply LF347-N in a vending machine on the 4th floor of their college of EE, so I grabbed a few of those.

I was able to get a 10 µF capacitor to hold < 1V of charge (tapping to the 9v with a resistor and then draining with a resistor while measuring) and then created the suggested non-inverted feedback loop with each of a 5k1 and 2k resistor on a breadboard with a 9v battery and see the expected 3.55v (1 + RF/R1). It seemed that the op amp was actually charging the cap, despite the no-in/no-out "guideline". Or it was just increasing from residual voltage as it settled.

(only using one for now with the basic "non-inverting feedback loop" for now, but considering trying the "instrumentational amplifier" or "two op amp inamp" next time)

Cool, I think I'm on the right path now.

I swapped out the 3.5x feedback (5k1, 2k) with a 101x feedback (100k, 1k) so that I could test with the thermocouple. I got an initial ~1.2V reading (maybe because I was below the rail limit?), but then it didn't change when I held my finger on it.

... and I could smell the Magic Smoke! Hot resistors. Hot op amp. I don't think it works anymore. I still get some readings, but they seem off and I don't trust it.

Tried a second time, similar result (gotta go back to that vending machine). At various points as I was experimenting I even tried touching my hot soldering iron to the tip, but never saw a response different from holding it with my finger through the op amp output.

What I'd like help with

what might I have done to burn up the LF347-N?

(it's rated +/- 25v input)

how do I bias the thermocouple's 0v starting point?

what happens if I don't? (it's not like the first 10˚C matter anyway)

is battery "ground" compatible with the thermocouple "ground"?

(they're both relative to themselves rather than ground ground)

I'm not ready to give up and use more specialized components like the MAX31855, LT1025 and LTC1049. I want to bang my head against this with "basic" components a little longer.

What else does a noob like me need to know to get on the right path? How might you go about this? What might I be missing?

P.S. Some related posts

Economical thermocouple amplifier circuit
https://www.eevblog.com/forum/beginners/amplifying-a-thermocouple-(for-learning)/


texts: Transducer output wires in grounded enclosure - to twist or not to twist?

texts:
I have a transducer totally enclosed in a conductive brass casing, which is grounded. One of the transducer outputs is grounded, and the other fed from the enclosure by a coax connector.

Internally, is there any benefit twisting the transducer output wires prior to their terminating on the coax connector and earthed brass? Signal is small amplitude (mV) at 120kHz

I believe not, but would like a second opinion


texts: Sequence Detector forced to wait a specific number of bits

texts:
So I have this little problem, where I am supposed to build a sequence detector which is forced to wait a specific number of bits before going into the reset state. It's kind of like pin codes work. You put the whole 4-digit sequence number and in the end it says if the output is true (1) or not (0).
An example our professor gave is:
A sequence detector waits for 4 bits and outputs 1 if the 4-bit sequence has at least two 1s.
If anyone does not mind explaining how to build a system like this or find me a lecture/notes/site/tutorial where I can understand this concept.
I can only use Mealy machines state diagrams.


texts:
I have a process that produces a digital pulse train from a rotary encoder. I need to be able to stop the process once a stepper motor has moved a given distance. The trick is, I need to manually set the length of the process, probably using a potentiometer. So what I'm looking for is something that takes the digital pulse train as an input and produces an analog voltage as an output, the voltage increasing with the number of pulses received. I can then compare this output voltage with the voltage at the potentiometer and stop the process when they match.

This stopping is secondary to the main purpose of the stepper motor, and is not a precise requirement; the exact number of pulses received is not important. I want to stop the stepper motor if it overruns its intended distance, so a potentiometer control is adequate.

I've been searching the web for articles that give a solution to this, but haven't found any. I've looked at digital-to-analog converters but can't find one that does what I need. Basically, it's a digital counter that produces an analog voltage output which increases with the input count.


texts:
I have read about matching networks, authors usually will describe a target impedance to be presented, to say, the output of an amplifier, and then they design the matching network. To widen the bandwith they usually create a matching network with more sections, thus, lowering the general Q and presenting the same impedance to a wider range of frequencies.

But my question is this: What's the point on presenting the same impedance over a wide range of frequencies if the S-parameters (and thus the required load/source to be presented to the amp) change with frequency? For example the optimum source impedance for LNA design is not the same at different frequencies, in a power amplifier the optimum load varies with frequency, so whats the point on designing a matching network that presents the same load over a wide range of frequencies?, instead, shouldnt a network be designed to "track"  those impedance changes, thus presenting the ideal source/load required for each frequency?, how is a network like that designed?


texts:
I'm working with STM32F103VE and STM32F746, and i want to use my Flash memory as EEPROM EMULATOR for writing and reading data easily.

I have searched for axemples of Emulation of EEPROM for my board but i found exemple of those boards '' STM32F0xx and STM32L4'' and i want to adapt the codes eeprom.h and eeprom.c to my boards.

What i should change? and where?

it's my first time with STM32.

Thank you.


texts: how to model AWGN for a Triangular waveform

texts:
If I want to generate some Additive White Gaussian Random Noise on top of my signal, how should I do it, if my waveform is triangular instead of being rectangular.
Because I am sure I have to somehow account for this in the noise variance, but I don't know how?


texts: ARM Instruction size vs Instruction encoding

texts:
I cannot make sense of the difference between 'Instruction size' and 'Instruction encoding' specially about ARM and Thumb ISA's as explained here:

Can we say that Instruction size is 32 bits but its encoding is 16-bits for Thumb-1 ISA and 32 bits for Thumb-2?

IS 'encoding' related to the binary code generated by the Assembler or is it related to the MCU internal architecture and not visible to the software developer?


texts:
Due to very bad SWR I have taken apart a Workman UVS-200 antenna and did a continuity test on the capacitors used for tuning. One of them seems to be bad. It is a small disc (I think ceramic capacitor) with the following markings on it:

first line - "9J"

second line - "1K?"(the letter is either U or V ... i assume V so it would read 1KV)

The cap is brown in color and also has a dot of black paint on top of it ... to be more specific the black dot is on the circumference of the disc.

All of the references I have checked for identifying a capacitor say nothing about such a marking with a single digit and a letter.

Please help in determining what capacity this thing has so I can replace it.

thanks,

D.


texts: Short-circuiting the primary coil of a transformer to keep it warm

texts:
I saw this problem somewhere and I wanted to give it a try, but the numbers I've got seem to be pretty outlying.

We have a 25kV / 4160V transformer which is out of circuit for now. To protect it from humidity in a freezing cold conditions, we need to keep it warm by short-circuiting its primary coil and connecting the secondary coil to a 208V, 3ph line. How much heat will be generated in this way? The transformer specifications are as follows.

My try:
Since the primary coil is short-circuited, all the loss occurs at the core. And since it is operating at 5% of its nominal voltage, the coil loss will be 5% of its nominal value, i.e. about 650 watt. Though I suspected that since the loss is proportional to V^2 then it would be even lower, but nonetheless, the numbers are way too lower than what I've been told (which was 57% of the full-load loss).
So I would appreciate if anyone guide me on how to approach such problems.


texts: Which mode to configure MP24833AGN LED driver when we need output voltage higher than input voltage?

texts:
The MP24833AGN is a good choice for an LED driver when we have a DC input of 9 or 12 V (or even higher) and need to drive bright LEDs which consume high current like 1A or more.
If your application is boost type, ensure that you use the buck-boost mode rather than dedicated boost mode.
This is because in boost mode the LEDs will glow even when the IC is disabled via Enable pin if the input voltage falls under the combined forward voltage range of the LED string.
If we use buck-boost mode, this issue can be avoided and the switching be enabled and LED string circuit be completed only when the IC is enabled usig EN pin.


texts: how can I "map" potentiometer value without microcontroller?

texts:
I want to make potentiometer that goes to 0 to 100% ONLY if I start to open it from 50%.
That means, if I open it to 51%, it will report as 2%. if I open it at 75%, it will report as 50%.

In Arduino, I can make it like this

int val = analogRead(0);
if (val < 50)
{
   val = 0;
}
val = map(analogRead(A0,51,100,0,100);
//okay that's stupid coding for sure.

How can I do this without arduino?

EDIT : I want to do it WITHOUT microcontroller.
EDIT 2 : I want to do it as simple as possible, and if possible without using any IC.


texts: My headphones have 4 wires instead of just 3

texts:
I cut into my headphone cable to repair the headphone plug and instead of the standard "3 wires" I read about all the time mine has four:

1 red (I assume right)
1 blue (I assume left)
1 white (???)
1 black (???)

These headphones don't have a microphone, so it's not for audio in.

UPDATE: I looked at some other documentation about this brand's design, turns out it's "left earth" and "right earth".


texts: Increasing 12V Rail current on power supply for mobile computing

texts:
I am building a miro-itx slimline pc for my mobile home that is powered by solar. I have selected a GPU with a rated TDP of 120 Watts and a CPU with a TDP of 53 Watts.I purchased a DC-DC buck converter ATX power supply the M4-ATX 250w rated for 12A continuous on the 12V rail.  I made the incorrect assumption that the CPU was powered by an onboard buck converter working on the +3.3V rail( would make more sense? It's rated @ 25A), and thus the CPU load would count towards the maximum. After a little research it would appear the CPU buck converter draws from the 12V rail, pushing my power demands out of spec. I have thought of a few solutions and am curious as to their viability.

1.) Parallel another power supply onto the 12v Rail (Buck/Boost with Constant Current set to enough amps to bring the unit back into spec Constant Voltage mode set at higher voltage then my current 12V feedback locked DC-DC M4-ATX).

This would effectively make the Device constant current, and lock it to the regulated voltage.

or

2.) Parallel another M4-ATX onto the current one and hope that line regulation is sloppy enough to prevent short circuit-like feedback loop.

I would prefer #1 But I do not want any fried expensive electronics.

Thanks for reading through my word wall.


texts:
I'm trying to read fuses for ATTINY85 using avrdude on Linux. I have Pololu PGM03A hardware programmer. I connected the ISP header to ATTINY85 the following way, except I'm not using crystal:

I verified all the connections with multi-meter. Now I ran the following command:

avrdude -c avrisp2 -p t85 -P /dev/ttyACM0 -b 19200 -v -B 4.0

I also tried setting -B to 250.0, but still the same output:

    avrdude: Version 6.1, compiled on Sep  8 2015 at 09:40:37
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "/etc/avrdude.conf"
         User configuration file is "/home/k/.avrduderc"
         User configuration file does not exist or is not a regular file, skipping

         Using Port                    : /dev/ttyACM0
         Using Programmer              : avrisp2
         Overriding Baud Rate          : 19200
         Setting bit clk period        : 4.0
         AVR Part                      : ATtiny85
         Chip Erase delay              : 4500 us
         PAGEL                         : P00
         BS2                           : P00
         RESET disposition             : possible i/o
         RETRY pulse                   : SCK
         serial program mode           : yes
         parallel program mode         : yes
         Timeout                       : 200
         StabDelay                     : 100
         CmdexeDelay                   : 25
         SyncLoops                     : 32
         ByteDelay                     : 0
         PollIndex                     : 3
         PollValue                     : 0x53
         Memory Detail                 :

                                  Block Poll               Page                       Polled
           Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
           ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
           eeprom        65     6     4    0 no        512    4      0  4000  4500 0xff 0xff
           flash         65     6    32    0 yes      8192   64    128  4500  4500 0xff 0xff
           signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00
           lock           0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
           lfuse          0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
           hfuse          0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
           efuse          0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
           calibration    0     0     0    0 no          2    0      0     0     0 0x00 0x00

         Programmer Type : STK500V2
         Description     : Atmel AVR ISP mkII
         Programmer Model: STK500
         Hardware Version: 15
         Firmware Version Master : 2.10
         Topcard         : Unknown
         Vtarget         : 0.0 V
         SCK period      : 8.7 us
         Varef           : 0.0 V
         Oscillator      : 3.686 MHz

avrdude: stk500v2_command(): command failed
avrdude: initialization failed, rc=-1
         Double check connections and try again, or use -F to override
         this check.

As far as I understood, ATTINY85 can run and be programmed without external crystal at 16MHZ, all I want to do is read the current fuse configuration and set it to run at 16MHZ so it can be programmed without any crystals and capacitors.

I had the same problem with ATMEGA328P, but connecting external power source to micro-controller solved the problem. I tried to do the same for ATTINY85, but still the same problem persists.

Any tips? Thanks

UPDATE: I added 16MHz crystal to pins 2 and 3 as well as 22pF capacitors connected between each crystal pin and the ground, but still the same problem persists.

[![enter image description here][2]][2]


texts:
Can someone help me in regards to calculating the impedance of a Dickson multiplier?
It consists of capacitors of 3.3 pF and 2850 shottky diodes. They can be assumed ideal. It consists of 7 stages, followed by a load consisting of a capacitor of 100pf and a resistor of 499 ohm.

The resistance of the load resisitor is 499 ohm, not 499k ohm


texts: Build a T flip-flop with enable and reset using only a JK flip-flop (without enable or reset) and some necessary logic gates

texts: Can someone help me to check whether my answer is correct or wrong, because I am confused with some of the condition of enable and reset. I am confused if the enable is low and the reset is high, should do flip flop perform reset or not? and also I am confused if both enable and reset are high, should I perform reset or follow the T input?


texts: What could cause impulse noise on switch closure

texts:
I have a simple SPST NO Tact switch which is creating a noise pulse in a very sensitive receiver.  Moving the switch, shielding etc is not possible.

I need to understand how the switch is creating is creating this noise, so I can kill it.

R2 could be increased in value, but I tried that without improvement.  This seems to suggest that it's the discharging of parasitic capacitance at the switch that is causing the noise.

R3 was originally intended to help prevent ESD near the switch from reaching the processor, but it also should prevent that trace capacitance from contributing to the noise.

The R3 and R2 are located right at the switch, which should minimize any parasitic trace capacitance that would be discharged when the switch closes.

I've tried adding 1k in series with the ground side of the switch, thinking the noise was caused by discharging the parasitic capacitance, but that didn't make any noticeable change.

I tried 1nF across the switch, and not surprisingly the noise got worse. That seems to align with the idea that it's parasitic capacitance at the switch causing the noise when the switch closes.
Adding C across the switch would also be a bad idea long term because the discharge current would exceed the switch rating unless I also added series R to the cap...

So, can anyone explain the mechanism by which the switch is creating bursts of RF noise on closure and/or how to prevent that?

EDIT:  We proved it's the switch by removing R3, and tying TP7 to VCC through 10k, so that the processor can't see the switch.   The contacts are a collapsing metal dome which touches metal contacts. I had to dissect a switch to find that out, the data sheet doesn't explicitly say so, but the resistance is 0.1 ohm max which hints that it's metallic contacts.

So it is the discharge of the internal capacitance, equalizing the voltage between the contacts, which is radiating the noise.

I'm starting to think that we just need to find a conductive rubber switch, and there may be NO practical solution to the original switch.

Edit: I'm well aware of the bounce, and debouncing is done in SW.  In the test where we disconnected R3, the RF pulses were still observed with no change at all, while the switch was physically disconnected from the processor input, and that input tied high to simulate the unpushed switch.
This is the first time I've seen this phenomenon in this type of switch.

You can see a similar phenomenon if you have a sensitive receiver, antenna, and two screwdrivers.  Set up the receiver down near 500kHz, and then simply touch the metal screwdriver shafts together near the antenna while holding the plastic handles. You'll hear clicking in the receiver. More or less strongly depending on the distance and the stored charge on the metal shafts.  In this case the switch is < 0.1 inch from the antenna, and we force a charge of 3.3V when the switch is open.


texts: Antenova M20057 active antenna is not working

texts:
I have decided to use Antenova product which is M20057 (datasheet) as an active GPS antenna. I am using Quectel L96 GNSS module.

There is an internal chip antenna on L96 module and I have tried the performance of L96 without M20057-1 before. I can get location data while the device is outdoors but we couldn't get the location data at indoors. That's why I have decided to use an active antenna to improve performance.

I have just received the PCB with M20057 and I am not able to get the location data either indoors and outdoors with M20057-1. It is obvious that there is a problem with the design of the printed circuit board.

I don't know whether the problem is the matching circuit (does it affect the performance that much,) layout, or schematic.

Could you please review my schematic and layout to check if is there a problem?

I know that it quite hard to detect the problem in this way but even your approaches might be pretty useful.

I am going to share screenshots of schematics and layout.

I would like to give so more detail about the design. I have uploaded two ss to describe how I think during designing the circuit. For L96 Anton pin has been designed for decreasing active antenna power consumption. Anton pin is only pulled high when the module is high. I haven't used the Anton pin. I am using pnp mosfet circuit as a high side switch to control the power consumption of GPS module so I connect the same supply to the active antenna in this way when the module is closed active antenna is also closed.

Please check the pin description and application circuit of M20057 it is written that AT1 should be connected to the ground.

In my design, there are matching elements on the circuit but I haven't soldered them. After seeing this pin description I have made a short circuit AT1 and AT2 to ground. I thought that was the problem but it changed nothing. So I am literally stuck.


texts: DC to AC conversion and filter wave shaping

texts:
My question refers to checking concepts.It's a scientific one,so I am not looking for a way to make a DC to AC power supply for a device because its charger broke or something similar.

The goal is to convert the output of an astable multivibrator into a sine wave that can drive a transformer in a decent way.

The way to do this:connect two low pass filters one to another.One will have a square wave  at the input and convert it into a triangle wave.The other will receive it and convert into a sine wave.

simulate this circuit – Schematic created using CircuitLab

I know that for each filter to work as an integrator,the time period of the incoming wave has to be smaller or equal to the RC time constant of the filter.I will calculate these accordingly.This is not the issue.

The problem starts with the square wave.I'm not sure if it should go below 0 or if it's ok to let it vary between 0 and +5V for example.The same is available to the triangle wave.I'm not sure if it will produce the desired sine wave if it won't oscillate between a negative and a positive voltage.

The question is:What kind of square and triangle waves should be generated so that a circuit such as the one described by the schematic will work as explained?Will a square wave (from the multivibrator) input which oscillates between 0 and +V make it work or should it shift from -V to +V?


texts: Why is the ripple frequency in dc side of 3 phase full wave converter is considered to be 6 times that of ac side?

texts: I can't find why is the ripple frequency in dc side of 3 phase full wave converter is considered to be 6 times that of ac side?


texts: Creating stepper motor driver using only TTL ICs

texts:
I am trying to drive a 5-wire unipolar stepper motor WITHOUT a microcontroller or driver ic, just using logic gates and JK flip flops (74LS107N's). The motor shaft needs to rotate a certain number of times to displace a set amount of inches in both a cw and ccw direction. The amount of inches will be based on an input sequence of switches / buttons. I am more concerned with driving of the motor than the displacement part right now. I have built an astable 555 with a potentiometer to adjust the clock signal frequency. I wanted to use this to somehow be the input to the "step driver" so that when I reach my displacement destination I can just ground the 555 reset and everything will stop. I have TIP120's and TIP42's to use also.

Any advice or push in the right direction would be greatly appreciated.

Thank you.


texts:
Let say Q2 is a power BJT like E13009 http://www.onsemi.com/pub_link/Collateral/MJE13009-D.PDF and I want to control the BJT through a microcontroller for example an Arduino.

I thought of this circuit and wondered is it good enough for switching the Power BJT? I didn't calculate the value of the resistors, they are just some common 1K and 10K resistors.

RL is my load and let say the load current is about 5A, Q1 is a general purpose NPN BJT, and SW1 represents the output from a microcontroller.

simulate this circuit – Schematic created using CircuitLab

Edited: The new schematic for D44H11

simulate this circuit


texts: Implementation of a correlation alogrithm

texts: I have been reading a document that implements a cross correlation between two signals by first multiplying them and then doing an FFT of the product. The implementation by multiplying the FFTs of the two signals is understandable since convolution in time domain is multiplication in frequency domain. But how multiplication in time followed by an FFT of the product is the same as cross correlation is not clearly understood.Could somebody help out please?


texts:
My son (9yrs) has become interested in robotics.  I did a course on it in college, but that was a LOOONG time ago and the course was much more rooted in programming than it was in electrical engineering.  So, I'm learning as I go so that I can keep the project as wrinkle-free as possible.

I know that pre-built options for what I'm building already exist... but I don't learn anything having someone else do it for me!

So... I wish to build a "dual stepper motor driver" (I'm sure there's a better name for it, but that's what comes to mind), I plan to take the main power source (12V) and push it through a 5V regulator to supply the logic, to make the board as "self contained" as possible, rather than rely on the Arduino for my 5V supply.

I've already got a 100uF cap across Vmot/gnd, but there's the 5V logic Vin/gnd.... should I put a decoupling cap on that, as well, since it's coming from the same power supply?

I'm inclined to believe "it's not needed but it's a good practice", but I wanted to ask and be sure.

As I understand it the idea is to provide a "current buffer" to protect against a sudden need for power which can in turn cause harmful voltage drop or noise, and the logic really wouldn't draw much in the way of current, all while the minimum voltage I expect to see from the battery is 11.7V near empty (still exceeding minimum that the regulator would need... right?).


texts: Why is a common mode bias required for this differential amplifier?

texts: TI makes the ADS1118 which is an ADC with a programmable gain amplifier (PGA). In one of their application examples (page 4), they indicate that small differential input voltages (1-2mV) must have a common mode bias. This seems unnecessary since common mode voltage will be rejected by the differential amplifier.  Why is a common-mode bias required? Will this work if the common-mode bias is removed?


texts: Is a capacitive touch screen safe to use?

texts:
I was reading about capacitive touch screens. I understood that your hand picks some current flowing on screen. That sounds alarming.

Is it safe to use a capacitive touch screen, since it picks small amount of current from screen?


texts: Simple Synchronous Rectification of Unidirectional Motor?

texts:
I'm trying to drive a high current, low voltage motor (24V 100A cont.). It previously used a very large and overpowered H-Bridge (16 FETs). The system only can rotate 1 direction, and is required to coast stop (no active braking).

So instead of a full H bridge, I figured it would be much more compact to drive it with a single low side FET (2 in parallel). Unfortunately the losses in the flyback diode would be quite large, then it occurred to me, I should be able to use a typical half bridge driver with dead time etc. built in, and just put the high side FET across the motor.

The body diode would conduct in the required times when the FET is not activated, and once activated it would have orders of magnitude less losses. One risk is the bootstrap system would eventually under volt when left on for extended time, but it would not matter as the motor would be stopped, and the body diode is still there for over voltage prevention in case of manual motion.

It seems to easy, but I have yet to find an issue with this concept. Am I missing something obvious? If not, hopefully this helps someone else in the future.


texts:
Given I am charging a 50uF film cap bank to 500V. Do I need a current limiting resistor or some sort of current regulator to minimize inrush current when i first turn on the power supply and/or limit the rate the cap charges?

My concerns are the PS not being able to supply this initial current or possibly damaging the cap bank.

cap datassheet:

https://www.mouser.com/datasheet/2/427/mkp1848sdclink-309918.pdf


texts: Including one module in another module with variable

texts:
I need to implement this code to synthesize and do so that xor21 and and21 will work separately.

module top(
 input a, b, x,
 output c
);

always @(a or b or x)
begin
    if(x)
       xor21 x1 (.a(a), .b(b), .c(c));
   else
      and21 a1 (.a(a), .b(b), .c(c));
end
endmodule

However, I get the following error:

  ERROR:HDLCompiler:1575 Instantiation is not allowed in sequential area
  except checker instantiation

How do I go about designing this?


texts: Simulating a specific MOSFET circuit in PSPICE

texts:
I want to simulate this circuit in PSPICE (to get approximate output waveform (\$v_o\$))

simulate this circuit – Schematic created using CircuitLab

Here, \$v_{in}=0.2 \sin(wt) , \$
& NMOS specifications:  \$ \mu_n C_{ox}(\frac{W}{L})=2mA/V^2 \, , \, V_T=1V\$
Also here MOS is acting as an amplifier [Given]

so,
My equivalent circuit in PSPICE is as follows:

simulate this circuit

and the corresponding .CIR code is as follows:
Vin 1 0 SIN(0 0.2 10K)
R1 1 2 1k
C1 2 3 1u
R2 3 0 1MEG
M1 4 3 5 5 my-mos L=1u W=1u
.MODEL my-mos NMOS (VTO=1V Kp=2m lambda=0 Level=5)
R3 6 4 7k
Vccp 6 0 DC 12V
C2 5 0 1u
Ibias 5 7 DC 1mA
Vccn 7 0 DC -12V
.tran 1us 200us
.probe V(Vin) V(4,0)
.end

Actual waveform should be like this:

But the simulated code is giving wrong results
It is showing V(4,0) or \$ v_o  = 5 - 1.4\sin(2 \pi (10k) t ) \$
i.e

Here, answer should be V(4,0)= \$ 5 - 2.8 \sin(2  \pi (10k) t \$ ).

so,have i missed any coding lines, or a better model of MOSFET can be used for this circuit problem;any suggestions please...


texts: ADC Measure from source with higher voltage and different ground

texts:
I would like to measure the voltage of a battery that varies from 4,5V to 3V.
To do so I'm planning to connect this source to a STM32F4 DISCO board and one of its ADCs, which will be set to a VREF+ of 3V. The conversion speed will be very low.
As the voltage from the source is higher than the STM32F4 Vref pin I need to add a voltage divider so that, taking into account I'll use 3V as Vref, the source maximum voltage (4,5V) is converted to 3V, something similar to the following schematic:

simulate this circuit – Schematic created using CircuitLab
I'm trying to understand how to proceed to have a real measurement voltage value at the ADC_IN if I'm dealing with multiple grounds in the signal conditiong path, Battery GND, 12V GND and Microcontroller GND.
So, I have to main questions:

How should I connect the ground nets to have a measurement as accurate as possible?

If I have multiple sources to read from and, each source has different ground, could I still have accurate measurements from all sources? How should these grounds be connected?


texts:
Suppose $t0 stores the base address of word array, $s0 is associated with position, and $s1 is associated with offset.I have to convert the following program segment into Assembly and write down the resulting array content
array = [0,1,2,3,4,5,6,7,8,9,10,11]
position = 0
offset = 1
while position < 11:
array[position] = array [position + offset]
position = position + 1;

so far i have written this-
   .data

array:
 .word 0,1,2,3,4,5,6,7,8,9,10,11
  counter:  .word 11

lw $t1,counter
 la $t0,array
li $s0,0
li $s1,1

loop:

beq $s0,$t1,end
lb $s0,0($t0)
add $s0,$s0,@s1
sw $s0,($s0)
addi $s0,$s0,1
addi $t0,$t0,4
j loop

end:

i dont know how to move forward from here , can anyone help


texts:
If one has some 216C 10A thermal fuses, could one wire two in parallel in order to fuse a 10A heated bed on a 3d printer? The bed is 110V and 1100W btw, so in normal operation it should draw 10A. Seeing as how this is right at the top of the current range, I thought I would put two side by side just to be safe.

I can't think of any reason this would not work, theoretically the current should be pretty evenly divided between the two, no?

edit: this is not a duplicate question! Why is everyone so quick to mark things duplicate on here before even reading the whole post?!? The "duplicate" question is even asking about fuses of different ratings- my fuses are identical.

The arguments linked in the other posts all have to do with current-limiting fuses. Thermal fuses blow at a particular temperature, and as long as they are within their rated current, one does not expect them to be used to limit current.

Again- two fuses in parallel, if given 10A, will theoretically each carry 5A. Even if the fuses are terribly mismatched, due to manufacturing irregularities, and one carries 8A and the other carries 2A, this is fine because we are concerned about max temp, not max current. As long as the second fuse takes at least 1A, then the other can take 9A and they will both be under the rated 10A. Then if the temperature happens to climb to 216C, they will blow. Why would this not work?

And if the answer is still no, at what current would they be acceptable to use in parallel?


texts: How to measure EC, pH, 10k thermistor, DO, and Ion-selective probes

texts:
Here are the sensors I am trying to measure and then convert into a 0-5V analog output:

pH (acid or base):  my understanding is you can use DC voltage to measure this sensor, just not sure what kind it is... impedance / resistive / inductive?

EC (electrical conductivity):  Resistive I believe, with an EC of zero giving a 1/1megaohm measurement?  has to be AC or you risk the probe wearing out real quick.

10k thermistor (temp):  same as EC i believe, a simple resistive sensor

DO (dissolved oxygen): no idea

ion selective probes(nitrates, ammonium, etc): no idea either, possibly the same as EC?

Once I get a grasp of how each type of probe is measured, what resources should I be looking at to tie it all together?  How do I reduce noise on the sensors if they are in the same container?  What are some of the better methods to test these out if I already have the sensors?  breadboarding?

A good example of sensors:  http://www.vernier.com


texts: Powering a self-drive piezo buzzer with capacitors?

texts:
I have a project I am working on where I want to power a "self-drive" piezo buzzer for 20-30 seconds. However, in order to provide the power to this piezo, I would like to ideally use capacitors in conjunction with a PMOS transistor to trigger the buzzer. (The alternative is to use a battery with a 555 timer to control the amount of time the piezo is on). However, I am trying to convince myself one way or another whether capacitors can deliver enough power to the piezo for that amount of time. I have not chosen a piezo yet, but I did find a 5V self-drive piezo here . However, a data sheet was not provided with the piezo to indicate average power consumption.

The bottom line: is this possible to do (without super capacitors)? Or am I going to have to go with a battery configuration?


texts: Combining Arduino and LEDs on same power channel

texts:
http://www.ladyada.net/products/pixel36mm/

Adafruit has a great tutorial on some square LEDs that I would like to use for a project. I have a regulated 12V 5A power supply that I would like to use. According to the instructions, it says to wire the power to the LEDs separate from the Arduino. My question is, how can I wire these things such that I do not kill either the LEDs or Arduino using a SINGLE power supply? I don't want two plugs hanging off the thing I'm making.

Thanks.


texts:
How can I test a mini capacitive microphone?
I have a mini microphone(something used in telephones) and I want to create a circuit to see how it works?
I want to speak to it and see how current or voltage or resistance changes as I speak to it


texts: Issues with coupling a buffer to an optocoupler

texts:
The buffer below between the input and the opto works fine itself, but Im having problem when Im interfacing it with 4n32 on the right. (Frequency of the hardware-trigger will be around 40Hz pulse train.)

As you see above the buffer output v_tr_out follows the input; but the opt_output is somehow effected like capacitively(?)

Where am I doing wrong, and how can I fix this problem?

MAJOR EDIT:

*Lowering the 100k solved the problem of capacitance.

Here is the more complete scheme with some updates!:

(please left-click to zoom in)

And here is the module input from its manual:

I have learned that -TRG and RTN are isolated innerly(they are not connected) so need to be isolated.

So I use different power supplies for tigger and power inputs to the module.

V1, V2 and V3 are power supplies for trigger voltage.
Vs is power supply for the input signal and buffer.
Vp is the 24V power supply for all the modules.

So in other words all supplies' negative terminals are not connected to each other. V1, V2, V3, Vp and Vs do not share their negative terminals.

Modules have their own trigger input and they only share Vp which is the power supply for the module. And trigger the inputs are coming from the same circuit i.e the buffer same output called tr_in.

STP cables will be used. And the cable lengths are 5m, 20m and 60m.

Would this scheme be fine for this scenario?


texts: What is "high voltage programming", and why do some MCUs use it?

texts: This article on sub-10 cent MCUs mentions that many of them use a high voltage programming interface.  What is this, and why would a product use it over a "regular" 5V or 3.3V programming interface?


texts: I need to develop an Ethernet encryption scheme. All that needs to be done is take the input on Ethernet and encrypt the packets and send them out the output Ethernet. Is there ANY way I could do this for $35 a piece? How about $50?


texts: If neutral line touches the live wire, how to protect the devices connected due to neutral fault?

texts: If the neutral line accidental touched the live wire, then due to momentary surge the home appliances connected gets damaged, what are the ways to protect the devices. Would RCCB be helpful to protect the home appliances. Initially I thought the devices are burnt due to high voltage hence installed servo stabilizer but even that got affected.


texts: Heating Element (resistor) to maintain temperatures in the 80-150°F in an incubator

texts:
I would like to maintain temperatures anywhere from 80-150°F inside of an incubator (an augmented cooler).

Yogurt ferments at 110°F, Bacillus subtilis at 100°F, certain sprouts do well at certain temperatures, etc.

I can easily whip up the scripts to control a relay based on a temperature sensor.

What I need help with is picking the heating element scheme. I am interested in making nichrome coils, or cupronickel is also on my mind. I understand that what I need are VERY low temperatures, but does not that imply only that I need very low voltages? (yes i know, current is what dictates the heat produced by a resistor, but of course that depends on the supply voltage)

Would DC power be applicable? Can I use the power available from my microcontroller? Am I crazy?


texts: I am measuring a signal with a lock-in amplifier (SR830) and sending this signal through a GPIB connection to a LabView VI. Should there be a coefficient on the voltage I receive in my VI to read the actual value? (For example, if the sensitivity is set to 10 µV, should I multiply the signal received by LabView by 1E-6?)


texts: Determine unhampered natural frequency and motor constants from graph?

texts:
I can find zeta from the PO given in the graph but I don't know any rule relate wn with tp
and I don't have value of the of ts and tr

For part b and c I don't know where to start

please help me to solve this,Thanks to all of you


texts:
I would like to build a circuit with two blinking LEDs using a NE555 timer and a photoresistor. In the schematic below the blinking frequency becomes higher when more light shines on the photoresistor (represented by the photodiode D1 in the schematic; there was no symbol for a photoresistor) and lower when there is less light. What I want, however, is the opposite: I want the blinking frequency to become higher when there is less light and lower when there is more light.

Can anybody tell me how to change the schematic so that it does what I want? I have to add that I'm not really advanced in electronics yet, so please understand if I did not provide information you need.


texts:
I'm so sorry for that questions, but we need to understand what's going on behind the concept/theoretical of using device "dependent voltage/current source"!

My question: Yes, we are using dependent voltage/current source, but is there a device like this in real life? If so, let's assume that at branch k there's voltage k, my dependent voltage source is at branch k + 5 in the circuit, so how does my dependent voltage source knows the voltage at branch k? theoretically we say just assigning it once we find it, but how it's going behind?!


texts: From transfer function to frequency response

texts:
In this question I asked about the difference between transfer function and frequency response. One user replied that "the frequency response is the transfer function where the transients are assumed to be completely dissipated". He showed an example, to prove his statement. It was like this:

  Take, as an example, a sinusoid, \$\small \sin(\omega t)
\rightarrow \dfrac{\omega}{s^2+\omega^2}\$, applied to a simple first order lag,
  \$\small G(s)=\dfrac{1}{1+s}\$. The response is: \$\small
> R(s)=\dfrac{\omega}{(s^2+\omega^2)(1+s)}\$, and this can be expressed
  in partial fractions:

  $$\small
\frac{\omega}{(s^2+\omega^2)(1+s)}=\frac{A+Bs}{(s^2+\omega^2)}+\frac{C}{(1+s)}$$

  Inverse LT gives:$$\small r(t)=\frac{A}{\omega}\sin(\omega t)+
B\cos(\omega t)+Ce^{-t/\tau}$$

  The exponential term decays to zero, leaving the steady-state response
  as:

  $$\small \frac{A}{\omega}\sin(\omega t)+B\cos(\omega t)= X\sin(\omega t+\phi)$$

  Solving for \$\small X\$ and \$\small\phi\$ gives \$
\frac{1}{\sqrt{1+\omega^2}}\$, and \$\small \arctan{(-\omega)}\$,
  respectively, as is obtained using \$\small s\rightarrow j\omega\$ in
  the Laplace TF.

I don't quite understand the last part.
How does he calculate \$\small X\$ and \$\small\phi\$ and what does he deduce by plugging \$\small s\rightarrow j\omega\$ into the transfer function? How is his original statement verified?


texts: Powering AtTiny85 with Adafruit NeoPixels

texts: I have an AtTiny85 and a series of 144 5v Adafruit NeoPixels. I'm following something similar to this tutorial: http://shin-ajaran.blogspot.com/2014_04_01_archive.html, but it doesn't mention if the current draw will damage the AtTiny85. I suspect it will. How would I wire this with a 5v 5a power adapter? I want to make the profile as small a possible, so the AtTiny seems the best route. I don't have much experience with Arduino projects larger than 5v, so any help is greatly appreciated.


texts: Calculating Resistance of Unknown resistor, total current and voltage across each resistor

texts:
simulate this circuit – Schematic created using CircuitLab

The circuit above has total power dissipation of 60 watts. I need to calculate:

- Resistance of R2

  Since it is given that total power is 60 watts, and the series circuit
  has 120v, then we can calculate total resistance to be RT =
  (120*120)/60 = 240 ohms

  We know we currently have a total known resistance of R1 + R3 = 180
  ohms. So R2 = 240 - 180 = 60 Ohms

- Current in the circuit

  If we calculated resistance of R2 correctly, then we know RT =
  R1+R2+R3 = 240 ohms

  We know voltage gain VT = 120 Volts.

  So total current: IT = VT/RT = 120/240 = 0.5 Amps

- Voltage across each resistor

  Voltage across R1 = V1 = (0.5 A) * (80 ohms) = 40 Volts

  Voltage across R2 = V1 = (0.5 A) * (60 ohms) = 30 Volts

  Voltage across R3 = V1 = (0.5 A) * (100 ohms) = 50 Volts

  To check if our answer is correct we total the voltages 40+30+50 =
  120 Volts which is our total voltage.

Are my answers correct?