texts: Mezzanine board connector recommendation

texts:
I plan to develop a mezzanine PCB intended to sit in place of two ICs in an existing circuit and replace their function.  Height is limited as the device is only 1U high in total.
One of the original ICs is a 28 pin 0.6" DIP 8kB SRAM, and the other is a 16 pin 0.3" DIP 74HC138 which acts as an address decoder.   My intent is to replace the 8kB RAM with a 32kB RAM and a GAL to act as an improved address decoder.
What would be the most appropriate connectors to use for the connection between the two boards ideally such that I can simply remove the board and re-insert the original ICs if desired?   The existing ICs are not currently socketed.  There's enough space available that I don't need to use the footprint of any such connectors to hold components.


texts: Pin names are getting skewed in Altium designer while printing

texts:
My friend is trying to print the schematic that was created in altium. Everything looks ok while viewing in altium but when i am trying to print it to PDF, the pin names and even port names are getting skewed. This is happening even when i use smart pdf to create the pdf.
It seems as if only things that has been rotated are getting affected by this.

It used to come properly in the beginning and suddenly it started coming like this after a few days.


texts:
In a DC circuit, why does a voltage drop appear across a poor connection in an open circuit?

For example, I have 48V DC wires, where a connector is charred from bouncing/bad contact. Under no load, the side of the connector reads 48V (the side attach to the supply), while the other reads 37V.

I don't understand how the voltage drop can exist without a current.

I believe my multimeter is equivalent to 10M Ohm when reading voltage. Does this mean the joint is probably 2.3 M Ohm, and its current of microamps though the joint and meter is giving the reading of 37V?

Also, when I make the connection good, at the other end of the 100m wire, I only get 47.2V. I understand the cable resistance will lower the voltage when a load is attached, but shouldn't it read 48V under no load? How can there be a drop of 0.8V across the wire with no load? Does this mean that there must be a leakage somewhere? If the meter is 10M Ohm, then this implies 160k Ohm through wire?


texts: What is such parameter called for a frequency to voltage converter

texts:
In a frequency to analog voltage converter what is the parameter which is related to the response of the conversion.

So for example I use this converter module and Im wondering how fast the change in the incoming pulse frequency has an effect on the change in output voltage.

What is such parameter called for a converter if there is such thing exists? (I cannot see in the module's datasheet such parameter)


texts:
I'm building a backup system for some computer hardware which is roughly a constant 20W of power at ~48V. I've built a 13S5P Li-Ion pack from the following cells. I'm experimenting with different charging voltages at the moment but I'm having a hard time charging the batteries under load.
I've set the charger to float at 4.2V/cell with the load connected. After fully charging, I'll disconnect the Power Supply, and the voltage drops immediately to ~3.2V/cell.
However, If I disconnect the load while charging, the batteries will stay at 4.2V/cell when disconnecting the Power Supply.
Do I need to charge the batteries at a higher voltage than 4.2V/cell? Do I need a better charger or power supply? I'm just not sure what I should be looking up to understand my problem better.
Thanks!


texts:
I have to make the frequency variable of an square waveform generator built with the help of an astable. I modified a circuit a found on the internet and everything seems good with only one exception: I cannot bring the astable to a low frequency without destroying the signal.

Whenever I raise the resistance of R13 (thinking about it as a potentiometer) to make the frequency lower, the signal waveform is getting worse and I can't figure out why.

I really don't have enough experience (I'm student) to make it work between 20-60 kHz without ruining the signal waveform. I thought if I add a variable resistor before the capacitors I can limit the current so the charging time of it, but I don't know why the signal is destroyed at a certain frequency. Do I have any chance to make it work like this or should I just think about another method? Or what should i modifiy to make it work?


texts:
Can anyone identify the black IC component for me please?
I have tried to find it I have no idea what it is, it is on the PCB for a piezo.

Full Image


texts: Grounding a switching PSU with AC mains neutral

texts:
I'm working on a circuit that measures mains current/voltage. I've seen the usual setup where a half wave transformerless simple circuit is used to supply couple of miliamps of power to run the IC that does the measurements and after that, an optional optocoupler is used to communicate with other ICs that run on isolated PSUs.

In my circuit however, the combined power consumption is in dozens of milliamps and the simple PSU above will waste too much power. I thought, why not connect the ground of a regular switch mode PSU ( e.g. a mobile phone charger adapter) to the mains' neutral lead and use it to power up my circuit. I've since been trying to find a problem with this solution and couldn't. Can anyone think of any problems or perhaps other solutions?

Note: I'm aware that such a circuit would be dangerous to humans without a proper enclosure (e.g. in case the live and neutral leads are swapped).

Edit: I didn't know how easy it was to add schematics here, so here's one to show what I mean:

simulate this circuit – Schematic created using CircuitLab


texts:
I'm having a signal that starts at 0V and linearly increases to 2.4V as output and I would like to buffer it such that it cannot be influenced by resistive loads.
The issue is that the only buffer circuit I've learned is the source follower (common drain amplifier) such that it takes  as input (gate voltage) the output of my previous circuit. But as this signal starts at 0V, the gate voltage is not high enough compared to Vthreshold and then the transistor is not in saturation and the circuit does not work correctly.
As you can see on this simulation, there is a delay before it starts following (also the slopes are not the same).

And here is my source follower with L=350nm and W = 1000nm.

Could you help me solving my issue. Either by suggesting another buffer circuit for resistive load or by having a trick so that the source follower can work for input lower than Vth.
Thank you


texts: DIY rotary inverter technical and economical feasibility

texts:
I’m setting up a solar panel system (200W) that’s used to charge batteries that will power small appliances in a converted van. Solid state inverters are expensive and difficult to fix and it seems something like a rotary inverter (generator) would be neither of those things. Perhaps I’m wrong, but that’s what I’m here to find out.

The requirements for the generator are that it can power sustained low power loads (<500W) and surges (900W) at ~120V 60Hz pure sine wave.

A soft requirement is the ability to change it’s output depending on the load. From what I’ve seen of solid-state inverters, they get very inefficient the lower you are from its rated load. The rotary inverter is a solution I’m exploring that solves that.

The reason I'm asking this question is because it seems BLDC motors can achieve high efficiencies (>90%), and if BLDC generators can do the same it seems like it may be worth it.

If they can, what implementation of this do you think is the best balance between cost and power efficiency assuming all new parts? Would permitting used parts change your answer?


texts:
I'm trying to improve my circuit layout skills. I'm currently working on a board that needs some current sensors. I've included a screenshot of the layout. I'm hoping some gurus out there can point out weaknesses in this design or some things I could do to improve it.

The VDD and GND vias go to solid power planes. The pins to the right of the I2C pins are address select pins. The bottom-middle pin on the IC is the voltage sense pin. A screenshot of the schematic is also included incase that makes it easier to tell what

Thanks in advance


texts:
I am designing a convertor board that will interface three device with Modbus RTU RS232 port to a Modbus RTU RS485 network.

Slaves supports Modbus RTU, but their ports is different from master port.

The ARM processor is intended to handle the communications of master RTU with different devices in the different addresses.
I konw the packet structure in the Modbus RTU protocol is as follows:

The question is: After receiving master packet and finding out the destination device (by reading slave ID byte), what should i send to the Device? Should i send the same packet that i received from master ? does it need to manipulate something (slave ID,...) within packet?

Thanks in advance

Best Regards


texts: I am using a old disposable camera to charge and discharge my Cap. I got 4 Caps and Connected them in Parallel (Hots to hots as is Grounds to Grounds). Can I use this just like normal? Can I just hook it up how it was or Do I need to do something else to the circuit.


texts: Can ultrasonic distance sensor be used to measure groundspeed?

texts:
Measuring speed when approaching an obstacle using ultrasonic sensor is pretty trivial. Take two distance measurements, divide by time between them, you have the speed.

But a sensor aimed diagonally at the ground, in horizontal movement, will keep giving the same distance readout. The only thing changing with speed will be the reflected frequency - doppler shift of the reflected ultrasound.

Can any inexpensive, common, compact sensors perform such measurements? Or would it require "cooking my own", with frequency analysis and such?

...or maybe I'm trying to force open an open door, and there's a different, simple, compact, inexpensive solution for measuring groundspeed at a distance of a couple meters? (other than GPS; this must be able to work in terrain with poor GPS reception.)


texts: PWM on negative pin to positive (the common) PWM for a fan's control pin

texts:
I'm currently modding a 3D printer (Anet E10) by upgrading it's fan to a powerful 3.4A 12V fan. It's model is 9BMB12P2K01. The current layout on it's PCB does not allow such a powerful fan to be connected directly to it's designated MOSFET because it looks like it can't handle more than 1A safely. I can't take the motherboard apart to see the actual circuitry for the fan control. My assumption is that the CPU (Atmega2560) uses a PWM signal for the fan control.

The standard fan cable plugs into a 2 pin socket connector (this type). By what I was able to measure, there is 0 resistance between the positive pin of the connector and the positive side of the power supply. There is infinite (or at least > 200 ohm) resistance between the negative side of the connector and the negative side of the power supply (GND). I am not experienced with MOSFETs, so I cannot identify it's type or layout. Judging by this measurement, the actual "PWM" is happening on the negative pin.

The powerful fan in question requires a PWM signal on a special pin. Thus, my question becomes:

What type of MOSFET is on the board? Is it an N-type, or a P-type? (it's covered by heatsink I cannot take off)
How can I use this (possibly) existing PWM signal on the negative pin as an input to the control pin of the powerful fan?

Edit: The powerful fan will be connected directly to the power supply, leaving it's control on the control pin. It expects a PWM signal on the control pin.


texts: Howcome I can't use assign operator on multiple bits?

texts: For the below image, howcome assign out = a&~sel + b&sel only outputs one instead of the ref solution below? Is there any way to do this problem with assign only?


texts:
We have this circuit

And using the simulator I found the load voltage at the resistor 10 k ohm, based on different frequencies. And I got this curve at the Bode plot. where Y axis represents the voltage across the load ( resistor 10 k ohm in the picture) and x axis the frequency.

Using this plot I have to predict the Vout at frequency 10 k Hertz.
I know that the output voltage should be reduced by a factor of 104( 80 dB), so the output voltage would be 250 uV.

But I am not sure I fully understand why we should use this factor, and how we used it to get the result 250uV.


texts: How does the C code relates to hex output in terms of pins assignment for ATmega16

texts:
So I wrote up a code which interfaces a graphic LCD with ATmega16 and displays some custom characters on it. This is a subject that I'm doing in my university. I would like to share the code with my peers but I don't want to share my code (I want them to learn by themselves). What I thought that I would share them my hex files which they could burn on their micro controller using avrstudio. They would just have to change one pin assignment to get the message displayed on their LCDs (and they would know if their hardware works).

Now I have had a little knowledge of using hex workshop for editing hex files for PSP and I was wondering if I could do so using that method. So I started looking of hex vales for that particular pin.

My LCD Chip select (on my PCB) is PB2 and I want other to only change this assignment. I tried to compile various versions of the code into hex formats in order to find the variations in the code and I found out three lines which got changed.

PB3
:1000E000A398A5980895C398C19A0E945B00C79AE7
:1000F000C39A81E090E00895C398C1980E945B0084
:10010000C79AC39A81E090E0089582EE0E947C0035

PB2
:1000E000A398A5980895C298C19A0E945B00C79AE8
:1000F000C29A81E090E00895C298C1980E945B0086
:10010000C79AC29A81E090E0089582EE0E947C0036

PB1
:1000E000A398A5980895C198C19A0E945B00C79AE9
:1000F000C19A81E090E00895C198C1980E945B0088
:10010000C79AC19A81E090E0089582EE0E947C0037

PC2
:1000E000A398A5980895AA98C19A0E945B00C79A00
:1000F000AA9A81E090E00895AA98C1980E945B00B6
:10010000C79AAA9A81E090E0089582EE0E947C004E

I was wondering how does AVRStudio assign the pin addresses(or something on those terms) while converting the code. Any help in this matter would be highly appreciated. Also this is my first time using Stackexchange, I hope I'm doing it the right way.

Thanks!
Sahil


texts: How to avoid a electrolytic capacitor on a (audio) signal path?

texts:
I've built a compressor basing on the all-in-one chip THAT4301. It works well. But I'm still not happy because of the electrolytic capacitor  I used in the signal path. My design was based on the reference design of THAT corporation:

The capacitor above is a polarized type. The signal is not biased before. As far as I know, this is a bad use. I also verified my concerns with a simulation. If the signal really containts a negative DC (which this cap tries to avoid) the cap would/should fail or blow.

So I want to replace it with a polarized type. However there is not really a good/small capacitor with such a high value, so I also would like to decrease its value. My circuit works with 10u and I cannot detect any cutoffs in the LF-Response. Still a big cap in the signal path.

I cannot calculate properly the value of this AC-coupling cap because I cannot find the input impedance of VCA (Voltage controlled amp) in the datasheet.

http://www.thatcorp.com/datashts/THAT_4301_Datasheet.pdf

47u would be necessary to pass a 10Hz-AC-Signal if the load had 330 Ohm input impedance! Isn't this freaking low? Can anybody read the input impedance out of the other values in the datasheet?
Why are they recommend a polarized capacitor for a non-biased input? I've seen this also in wikipedia (also frequently mentioned here).

What kind of possibilities do I have to avoid such big AC-coupling capacitors in the signal path?


texts:
I have the above simple requirement, and I'm frankly astonished that I can't find it as a simple chip.
My understandings:

USB2 provides 5V on its power pins;
USB2 assumes 100mA, but will provide 500mA upon negotiation;
Most USB2 sources just provide 500mA anyway - but I want to be "official" and negotiate for it first;
USB3 does "power delivery", but those chips are SO complex that they're overkill for my situation.

I have a 500mA, 3.3V circuit (330mA @ 5V) that I'd like to power from 5V USB. So I'm looking for a simple chip that has 4 USB pins (I assume the Data pins are part of the negotiation!) and one 3.3V output pin that can supply 500 mA - noting that ~750mA is the theoretical maximum. If there needs to be a couple of extra pins for support components (capacitors, inductors, etc.) then so be it, but I'd hope there wouldn't be many.
I've found all sorts of devices for USB chargers (on the "host" side - no good), USB Hub controllers (to even out multiple ports' requirements - too complex), USB peripherals with incidental output voltage (e.g. FTDI - way too complex), and even one 8-pin device that's almost ideal - but it stops at 200mA (300mA @ 3.3V).
Why isn't there a device that negotiates for 500mA, and then simply delivers it at 3.3V @ 750 mA (or close)?


texts: Low noise transistor series pass voltage regulator

texts:
I'm currently working on a series pass voltage regulator within LTSpice.
Here is this circuit:

I have read that these circuits are prone the oscillating and being unstable? This is one concern, the next is there is very little current travailing though the zener diode (170µA, equates to 2mW.) to hold regulation. I know its common to include another resistor from the input voltage to the cathode of ZD1 to combat this, or maybe reduce the value of R1 and R2. Both increase ripple on the output considerably, and I need this supply to be a quiet as possible as it will be used to power high-gain audio circuits.

What are the down sides of removing the zener and just keep R3 and R4 which will be a multi-turn potentiometer?

Will this be reliable and stable? even with large capacitance on the output?

How can LTSpice tell me the ripple rejection in dB?

Thankyou :)


texts: Can I use ethernet instead of DMX for DIY led lighting?

texts:
I've read that while most pro-lighting is uses dmx, some intelligent lighting rigs use ethernet. I'm interested in building some MCU controlled L.E.D. footlights for my stage show, and currently know nothing about dmx and damn little about lighting period. Would love to hear pros and cons of just using ethernet protocols instead. From my perspective as a pro-coder/hobby-EE, the path of least resistance would seem to be OSC over ethernet between my controlling machine (likely a Pi or something) and the lighting brains, (likely something like a Teensy). I am definitely on Mount Stupid in this area, input appreciated. I have built controllable l.e.d rigs on costumes already but nothing powerful enough for stage lighting.

Edit for clarification based on comment:
In our case, interoperability with standard controllers is not a concern at all, but reliability definitely is. We are jugglers, and we are almost never a priority with the lights and sound guys, so we are trying to build a system where we roll in our stuff, drive off our controllers that we start, and tell the regular light/sound guys to do nothing until we're done. In a corporate gig situation we don't trust them to hit our cues EVER. lol

thanks!


texts:
I bought 100uH inductor for my boost converter, one toroidal (DTPU100A3) and one bobbin (DSZ-9/100/2,2-V), both form faryster.
In the beginning, I thought both will give me same results, but the toroidal needs frequency below 40kHz to achive expected results. At the same time, it generate high-frequency noise and heats up. The second one gives same results or even better at frequency above 100kHz, without heating and noise.

I also though the toroidoal will not heat beacuse of its size but it looks like I'm wrong.

So where is the difference?


texts: PNP Transistor Not Working as Expected with Higher Voltage

texts:
I am a novice with electronics, I may know what my issue is but wanted to put this out and make sure my thinking is correct.
The below circuit is one I am using to turn on an LED when charging a battery and turn off when the battery is complete for an amplifier I've designed. What is happening is the LED never turns off. 0.74V is coming from a pin on the charging module's IC. When it turns off it is about 10V. This was working fine with a 12v AC adapter as I was waiting on my 15V adapter to come from China. Foolish me, I completed my PCB design and placed the order before I was aware of this issue. Sure I could just continue to use a 12V adapter but the circuitry is more efficient with the 15V when charging and listening at the same time.
I am hoping I just need a different transistor, my current one is a 2N3906. From looking at the datasheet I am thinking my Emitter−Base Breakdown Voltage of 5 is not high enough and if I switched to something like a KSA708 with an Emitter−Base Breakdown Voltage of 8 I may get the result I am looking for with this project. Any insight would be greatly appreciated, thanks.


texts: Anybody know what this DB25 jumper connection is called?

texts:
I'm in the process of motorizing a few electronics project.  Been racking my brains with Google and Mouser trying to identify the following part that is connected to a DB25 connector.
It looks like some kind of board with header pins, but as I am an electronics novice have no idea what this is called.  Using jumper wires seems like a nicer semi-permanent solution than a breakout box.
Here's the suspect:

Any help on this is appreciated!


texts: Current Limiter, can someone troubleshoot this circuit?

texts:
so I am trying to limit the current output with x2 3904 transistors and a sensing resistor. This is currently what I have, but am not sure why it doesn't work.

That current supply is going to be a photo-resistor (or something along those lines). The line going out is hooked up to a constant 10V DC. So right now with this simulation I am varying the current from 0-10mA, however I want it to limit at 3mA, how would I achieve this? Is this circuit even wired correctly? Any help is greatly appreciated. I also don't exactly know how to choose the value for R5 (in this circuit).

PS. I don't know if it's needed, but the output voltage should be around 6V. And ouput is the lower of the 2 wires going to the right of the screen.


texts: Repairing a 1983 V65 magna Instrument panel

texts: The Regulator/Rectifier died and overcharged my battery and killed the a few components on this board. The component in the second image is kind of unrecognizable and I'm not sure what Z is on the PCB. I just need some advice on how to repair this. I feel like I should replace a few of the resistors and capacitors but any advice is appreciated.


texts: Implement RS485 or I2C protocol using the usb-c connector?

texts:
I was wondering if there's any reason why I can't implement RS485 or 12C communication on the data pins of the USB-C connector?
I can't find anything on the internet that tells me not to.


texts: Cable TV Directional Coupler specifications - What SB means?

texts:
I have one Holland directional couples with this specifications:

In DCG-20SB
Directional Coupler
5-1000 MHz

Cable In/Out:

In DCG
Out 12SB
Tap

Similar one (this is 9SB):

What does 20SB means? Can I switch it for one having 12SB instead of 20SB?


texts: what is normalized transconductance uesd for?

texts:
The transconductance is defined e.g. for BJT by

gm = dIc/dVBE with VCE=const  (1)

where Ic is the collector current and VBE is base-emitter voltage, and from (1) we can deduce

gm = d( Is*exp( VBE/(m*VT) ) )/dVBE,
   = Is*exp( VBE/(m*VT) ) * 1/(m*VT),
   = Ic * 1/(m*VT),    (2)

and then the normalized transconductance is defined by

gm,norm = gm/(Ic/Vt)  (3)

where Vt is the thermal voltage, Is is the saturated current, m is the linearity factor related to the technology. In my master thesis, I focus on the variation of gm,norm with changing the doping profiles of transistor, the target is to improve the gm,norm by design the transistors. I can understand that, with a higher gm,norm the transconductance of the device is better. But why do not we use the gm directly? Is there any superiority using normalized transconductance rather than transconductance? Can someone tell me also the meaning of transconductance in the circuit design?
 Thanks a lot!


texts: I am trying to create a speed control for a brushless AC motor, like those used in fountain water pumps.  Since the speed of the motor is determined by the line frequency I want to make a low frequency (20 to 60 Hz) high voltage (120 V) oscillator.  Any ideas?  The pump is 7.5 W at 120 V.


texts: Help with deciding amplifying factor, small circuit

texts:
Hi,

To decide the amplifying factor \$A\$ of the circuit above I take \$A=U_{out} /U_{in}\$.

\$U_{out}\$ and \$U_{in}\$ is derived like this:

\$U_{out}=\frac{h_{21}I_B}{1/R_c+1/R_3}\$ (1)

\$U_{in}=U_{GS1}+I_Bh_{11}+(I_B+h_{21}I_B)R_E\$ (2)

Now I need one final independent equation for \$I_B\$.

\$I_B=\frac{R_2 g_m U_{GS1}}{R_2+h_{11}+R_E}\$ (3)

Am I thinking correct or are the derivations wrong? I just need help with the derivations of these thre expressions. The small signal model is assumed to be correct.


texts: Charging Li-ion batteries at a constant current for a fixed time

texts: I just saw an Ebay Listing for some cheap Li-Ion batteries and a charger that claims to be "safe" yet doesn't seem to have any overcharging protection as such - the charger is supposed to provide a "constant current" for a fixed amount of time. Am I wrong to assume that these batteries would perform better as fireworks than charge storing cells?


texts: Cheapest way of rectifying 60hz -> 30hz 120V AC to halve speed of PSC induction motor

texts:
I am trying to slow down a PSC motor.  (VFD’s are expensive)

I can cheaply rectify AC into the following waveform.

2 positive peaks then 2 negative peaks repeating.
It would look like pictured.

If feeding this modified AC waveform into an induction motor, would the resulting synchronous speed become halved?  Or would the motor work like crap/not at all? (Maybe some caps could smooth out the dip between consecutive peaks for better performance)

What’s the cheapest way to halve speed?

I don’t want to operate at high slip with reduced voltage due to potential hum.

This motor is running a fan and I want to reduce speed/CFM to quiet the monster down.


texts:
I'm using a Hobby King remote and 2.4ghz receiver to control an animatronic head. I'd like to enhance things a bit by putting a 5V SMD LED (ws2812b type) in each eye. Each channel of the receiver has 3 pins: ground, Vin and PWM. I get plenty of power to light the LED, but I'd like to use the PWM info (ideally without a microcontroller) to determine how bright the LED is. Depending on the position of the transmitter's potentiometer, the output voltage on the PWM is between .13 and .36.

Simply put, when the servo for the eyelids are in a closed position, I'd like the LEDs to be off or super dim, but when they are open, I want them to brighten up, all menacing like. Is there a simple circuit to facilitate this, maybe using a transistor or 555 timer? Or am I gonna need to use a 'duino to read in the PWM and pass it back out to light them up.


texts: How to find power efficiency in DC-DC converter circuit

texts:
We are currently simulating a dcdc converter called the LTC3108.

The input voltage is 500mV and the output is 3.3V through the dcdc converter.

Here we have to calculate the efficiency of the circuit

efficiency = E_out / E_in = I_load * V_out / I_IN * V_IN

The load resistance and the capacitor were placed on the output side, and the output voltage and output current of the resistor were measured.

So, the calculation is that we need to know the voltage and the current. Now the simulation values are as follows.

So, you can see that efficiency calculation is strange ...

How do I calculate it?

E_out / E_in = (500mV * (-267.72mA)) / 3.3V * 33uA = -1225.

What is strange? I want get % value.


texts: colpitts oscillator does not work with small inductance

texts: Hi I am trying to build a colpitts oscillator with frequency of 10K Hertz. This circuit works fine with L2, C3 and C4 as they are in the picture. However, there is no way I achieve 10mH of inductance even with winding a toroid due to lack of material. So I had to decrease it to 100uH as this is the inductor with highest inductance that I can find in my school's lab. I re-found capacitor values as 2.5uF and 0.25uF using a online calculator with feedback fraction of 10%. However, the circuit does not work now. I tried and played with everything, even I tried unity gain amplifier to isolate tank circuit output before it is given to C5 for coupling, but it does not work. What can I do? Oscillation does not start. The bjt below has approximately 0.7V base-emitter turn on voltage and its current gain is about 300.


texts: Question about outdated "amplidyne" technology

texts:
Can someone please help me understand something better about "amplidyne" technology that was used back in the day.
What I know
It appears to be a dc motor generator that acts like an amplifier which then allows excitation to be varied by small amount (input power) to produce large output power.
Referencing the conditions and picture provided.
R = 1 ohm
Terminal v = 100 v
Amps = 100 amps
Input power = 100 watts
Output power = 1000 watts

What does the following statement mean: It will be found that when R is zero, the field current required to circulate 100 amperes through the short circuited armature winding is only about 5% of the field current required when terminal E is 100 volts.
Does this simply mean that field current to produce 100 V will be less with shorted brushes compared when  the brushes not short-circuited?
Thank you for your help.


texts: Failed to get desired output of a pulse width modulation circuit simulation

texts:
I was given an assignment to simulate this circuit by first adjusting the variable resistor to get V=0 at the non inverting end of the opamp then observe the waveform at the output.
I am getting an AC wave at the non-inverting opamp and when I change the variable resistor value it reaches +12 at R=100% and -12 at R=0. Anything between makes an AC wave.
How do I get V=0?
I attached a picture of the circuit below and the AC wave:


texts: Reliable way to transport data over 1-2 km distance

texts: I am looking for some way to transport data (around 3000Kbps) omnidirectional. Transmitter should not weight more than 300 grams but receiver can be much heavier. The range I am trying to achieve is 1-2km line of sight. Is there any reliable hardware to fulfill this role?


texts: Which circuit to use to automatically turn off the backlight of a GLCD after 30s?

texts:
Have you ever seen smart phones automatically turn their screens off after a short time to save the power?

I want to do it on the back light of my GLCD (ks108sed).

Descriptions:

Back light will be turned on by a tactile switch.

Back light will be turned off after 30s.
The circuit shouldn't have a microcontroller.

What circuit should I use ??


texts:
I'm studying the following circuit

The image is explicit but as you can see the input measured in the upper terminal is a square wave with \$E_c\$ and \$-E_c\$ as levels.

Now I also had no trouble understanding that if \$R_B \leq \beta R_C\$ when the square wave is in the positive half-cycle we have saturation and when it is on the negative half-cycle we have cutoff situation.

Now in saturation we will (because the junction voltages are zero) an output voltage of zero. That is correct with the figure. However when we are in cutoff, applying KVL to the output mesh leads us to

$$U_{CE}=-E_c$$

because currents can be neglected.
That however is not concordant with the figure which shows $$U_{CE}=E_c$$
Why is that? What am I missing?


texts: How to control the temperature of heating element

texts: I am developing a heating application where temperature need to be constant. I am planning to set the temperature @ 200 degree C. when my sensor find the temperature exceeding the set temperature how can i reduce the temperature of the heating element. I currently plan to cut the supply to heating element but is there any other method which i can reduce the temperature.


texts:
I have done a simulation of a simple circuit using Multisim software to simulate the behaviour of the coil in DC circuit. The behaviour of the coil in DC circuit is shown by the below picture:

However using the Multisim software, when I open the switch S1 I obtain a negative voltage through the inductor not positive voltage as indicated in the first picture above:

Same things, when I close the switch,  I obtain a positive voltage (inductor charging) not a negative voltage:

Is there any explanation for this issue?


texts: Can I sum up multiple, alternating series capacitors and resistors like this?

texts: When the components are between each other, can I sum up multiple, alternating series capacitors and resistors like this? Thanks.


texts:
I have a small floating point unit, described in VHDL, and synthesizable. I'd like to buy an FPGA (not an expensive one) that would allow me to test in practice the unit.

I've used an FPGA in the past, a virtex-5, which is too expensive for what I have to do. I wanted to buy the cheapest I need for the task I have in mind.

I'm not an expert in purchasing this stuff however so I was wondering.

When I buy an FPGA is usually some licence to use some EDA tool also sold?
If the answer to 1. is NO, how much could cost a licences?
Is there anything else I need to buy for what I want to do?

Thx


texts: Complex Numbers, Phasor Notation, and Eulers Identity

texts:
On Page 30 in the Art Of Electronics (2nd Edition).

The two images below describe the conservation of Sinusoidal signals to a complex representation and back.  I am perfectly ok with the first image.  The next image has me stumped.

In particular, I am stumped at the description of V(t) and I(t)

For V(t), I understand why they say
V(t) = Re(V * e^jwt)

I do not understand the next line of the simplification
V(t) = Re(V)cos(wt) - Im(V) sin(wt)

e^jwt should simplify to

cos(wt) + jsim(wt), I don't understand how V is distributed to the second equation.

I guess I(t) would follow similarly.  Can someone help with the factoring?


texts:
I've been working on a project of power converter in OrCAD software and I've come across such problem. Here is a piece of my schematic.

A Q1 transistor is in an SOIC-8 package. A Source pin is connected to
I created a netlist and exported it to the OrCAD PCB Editor

My problem is as follows: Net name is OK, but why I don't see a logic connection between those two pads?


texts: The CPU has registers, but doesn't the RAM have registers too?

texts:
At low-level, registers are the same as a bunch of flip-flops connected by the same clock, so I would think RAM is made of registers.

I've been reading, though, that registers are only in the cpu, which I don't understand.

There are indeed registers in the cpu, ax, bx, etc, but aren't there other registers in memory (RAM) as well?


texts: Switching Regulator Voltage Dropping Unexpectedly

texts:
I am trying to determine what exactly is causing the below switching regulator/ DC-DC converter module to not maintain its rated output voltage.

http://www.meanwellusa.com/productPdf.aspx?i=794

I am using the SPBW03G-03, which has a listed maximum output current of 700mA and an output voltage of 3.3V. The input side of the regulator is driven by approximately 45 VDC (32 VAC rectified), which is within the 18-75V input voltage limit.

What I have observed is that essentially any load will draw down the output voltage of the regulator. At full load (all inputs on, all outputs/relays activated), I am drawing approximately 150 mA, which is well within the maximum output current of the regulator. The output voltage at my full load case drops to right at 2.98V, and holds there. When the load is removed, the regulator returns to just under 3.3V (measures at about 3.28 with DMM and Oscope). The voltage drop is most pronounced when the three relays are activated (note: the relays are rated for 3V operation) with the rest of the circuit having relatively small impacts on the voltage.

Below are snapshots of my schematic. I should note I have a dummy load in for the TeensyLC just for circuit testing, and am manually triggering inputs and outputs. I apologize for the regulator not being shown, I have not gotten around to adding it to my schematic yet.

This is the first project for which I have used a switching regulator, so am am wondering if there are any significant pitfalls that I could be missing. The Meanwell documentation is limited, but I know most of the other DC/DC modules suggest input and output capacitors, which I currently have not implemented.

If anyone has some suggestions as to what the issue might be, or what noobie mistakes I have made, I would appreciate the feedback.


texts:
Is the following a correct understanding of what makes a NPN/PNP transistor turn on or off?

NPN (more common)

Must have voltage > ~0.7V on base
Must have (conventional) current flowing into collector (top)

PNP

Must have zero voltage on base
Must have (conventional) current flowing into emitter (top)

Are the above two conditions accurate for each? And Are there any other 'requirements' to turn on a NPN/PNP transistor?


texts: is it OK to replace higher ampere TRIAC for a washing machine?

texts:
I have a 6 year old top load washing machine which requires a TRIAC replacement for wash motor. The actual TRIAC that came with factory PCB board is NXP BT138X-800 and the one I am looking to replace with is BT139-800E. These are passivated, sensitive gate triacs and from the datasheets I can see some differences in characteristics specifically under IGT(gate trigger currents) and IL(Latching currents).
The wash motor is connected with a capacitor and then to a TRIAC on to the PCB board. Here is the tech specs for
Wash Motor
220-240V 50HZ 125W 1.28A 4P
Capacitor
Rated on motor plate: 11uF/450VAC IPOO ClASS B
Currently using EPCOS LCAP 10uF +5/-0% with Inductor coil 110uH +/-7% Part No - B32350 (450VAC P0)
Note: EPCOS product sheet has mentioned 3 other TRIAC parts like ACST1235, ACST1035, BTA12-800CW but as of now I couldn't find them nearby.


texts: Effect of slight variations of load capacitors on frequency accuracy of a pierce oscillator

texts:
I have currently understood how to calculate capacitors C1 and C2 needed to be connected to a crystal to make its frequency stable in pierce oscillators.
Regarding the following equation, C1 and C2 are calculated:
C1=C2=2*Cload-2*Cstray
Cload (load capacitance) can be extracted from the datasheet of the crystal, however the Cstray can not be measured exactly. This made me ask you, how much will slight variations of c1 and c2 can affect the crystal frequency in room temperature? I make an example, How much do I lose accuracy in a 8MHz pierce oscillator, if I choose 20pF ones, while I should implement 10pF ones.


texts:
For the above circuit,

Natural response will be A×exp (-t/RC) where A is any constant.

For forced response, capacitor is open circuited consequently, 10K resistor is also removed and thus, forced response is 10Cos (2t).

Plugging into the eq. For V (t) and solving at t=0 I get A=-5. But still I am not getting the answer printed in the image. HELP NEEDED!

THANK YOU


texts: Batteries in parallel vs voltage signals in parallel

texts:
From a practical point of view, when you connect two audio signals to one speaker the result is that both audio signals can be heard. That means the two voltage waves were added, correct?

However, when you connect two batteries in parallel, the resulting voltage is not the sum of both batteries, it's more like the average.

This is all from real-world observasions. I don't know if this two cases are supposed to be conceptually the same.

Why does the voltage bahave differently in this two cases?


texts:
I've got a simple tig welder that uses a switch on the torch to start the welding current and a potentiometer on the front panel to set the amperage. Many welders make use of a foot pedal to start te welding current and also control the amperage level with your foot for a bit more control of the welding action. This welder doesn't officially have a way of connecting a foot pedal but I think it must be possible and tried adding one.

I bought a foot pedal that has a two pin connector and a three pin connector. The two pin connecter wil connect to my tig welder as is and it will trigger the welder to start just like the button from my torch would. I've now got foot control but can't manipulate the amperage.

Inside the welder the pot meter is hooked up to the connecter circled red. The outer lobes trace to a bunch of resistors and the centre lobe traces to two pins soldered together on the unused connector circled yellow. Maybe that connecter is there for adding a foot pedal. I can't seem to find any info on this welder anywhere.

Back to the pedal. The three pin connector is coming from two potentiometers in the pedal. Wired as follows.

I could match the potentiometer value of the pedal to the one in the panel but I would also like to be able to set the max current on the front of the panel and use the foot pedal to control the amperage within that range.

I've got it sort of working now by swapping the b103 10k potentiometer on the back of the pedal and hooking up the 1k potentiometer from the panel like can be seen here.

It is however not working as it should. I can only see and set the max amperage when the pedal is fully pressed. Also it won't go as low as it used to due to incorrect potentiometer value. I am sure there is a better (correct) way of doing it. Any help would be much appreciated!


texts: FPGAs or CPLDs for "Glue Logic" and Video/LCD Capabilities

texts:
Some of you may remember I posted a question in which it was suggested that I use CPLDs instead of a large number of multiplexers. Here is the question, for reference.

However, as I read and learn about CPLDs and FPGAs, I realized that FPGAs are also used for video capabilities. My project is going to need something like a 6" to 7" Color LCD in any case. Note, 24 bit color or such is not required. Even an 8-bit display is more than enough for this application. But I cannot help and wonder - would it not be better that I used an FPGA instead of CPLDs? This would mean less chips to work and it will get rid of a microcontroller, possibly.

With my limited knowledge, the reasons that FPGAs don't seem like a good solution are:

Are likely more expensive than CPLDs.
A mid-range FPGA might not be handle all the logic required for the application, along with video. This implies that I may need more than one chip. At this stage, a relatively powerful microcontroller and CPLDs become more attractive. The CPLDs can be configured for all the logic required and the controller can be the brains.
FPGAs will require a programmer onboard as they cannot retain their programming. In comparison, CPLDs are instant-on.

Why do they seem like a good option:

Can possibly replace several CPLDs and micro controller.
More support available for FPGAs than CPLDs.

Note that I cannot use a powerful FPGA for two reasons. They are very costly and secondly, they most probably come in BGA packages. The local manufactures are able to handle BGAs but its not recommended (I asked).


texts:
I am currently building a 3D scanner turntable and I can't figure out what stepper motor I should buy.

Here are some things to consider:

The plate will be made out of 3/4" MDF and will be 2' wide (diameter);
The plate's weight will be supported by a ball bearings system (just like a lazy susan);
I need to support objects with a weight up to 5 pounds;
The motor's shaft will be placed directly in the middle of the plate (no gears system, for maximum precision and simplicity);
I need a motor accurate enough to be able to calculate/simulate camera angle;
The turntable will turn at a very slow RPM (1 RPM or less);
I will be programming everything in a C/C++ program.

Here are my questions:

NEMA-17 or NEMA-23 (and why)?
What controller would I need? How can I communicate with the motor from a C/C++ program (Arduino or not)?

I was considering these:

NEMA-17:

Arduino UNO with Adafruit Motorshield V2
A NEMA-17 stepper motor with a 0.9° step angle

NEMA-23

Phidgets controller (still a little too pricy for me): http://www.phidgets.com/products.php?category=13&product_id=1067_0
Phidgets stepper motor: http://www.phidgets.com/products.php?category=23&product_id=3330_0

Thanks!


texts: Shift register explanation (parallel in - serial out)

texts:
The task is to implement a 4-bit shift register with parallel input and serial output using JK flip-flops and standard logic gates. The solution is below:

This is what happens on the output:

I don't understand what the SHIFT/LOAD is. Can you please explain what happens in this register if we want to input the number 1010?


texts: Very low frequency (<1Hz) high pass filter design

texts:
I want to design a very low frequency (<1Hz) high pass filter.  I was thinking of using a 2 pole sallen-key opamp design with a pair of r's and c's.  Is there anything special I need to consider when choosing component values/types.  It looks as though the caps will need to be in the 100's of µF range.

Thanks


texts:
I am having a problem applying the principle of linear superposition to the circuit below. My main problem arises in not know what to do with the capacitor and the inductor in parallel as well as the differing angular frequencies, how does differing angular frequencies change the summation of the two sources? Does it even change the summation?

I understand that I have to open circuit the current source and short circuit the voltage source and so I assumed in order to calculate the voltage source contribution I would get

$$30\sin10t *\frac{((1/0.4)+(1/1))^{-1}}{((1/0.4)+(1/1))^{-1})+4}$$

Also would I be correct in saying that due to the current division theorem, the voltage across the capacitor is also the same voltage across the inductor?

Do the same for the current source and add the two?


texts: Why doesn't my opamp relaxation oscillator oscillate?

texts:
I have designed a relaxation oscillator with an opamp. It is supposed to oscillated at 50Hz, but it doesn't. I haven't built a physical circuit, I'm trying to simulate it in CircuitLab.

I calculated the oscillation frequency with the circuit element values in the schematic as

$$
f = \left( T_c + T_d \right)^{-1} = 50.17Hz.
$$

Where, \$T_c\$ and \$T_d\$ are charging and discharging times of the capacitor respectively;

$$
T_c = RC \ln \left( \dfrac{(+12V) - \dfrac{R_2}{R_1 + R_2} (-12V)}{(+12V) - \dfrac{R_2}{R_1 + R_2} (+12V)} \right) = 9.97ms, \\
T_d = RC \ln \left( \dfrac{\dfrac{R_2}{R_1 + R_2} (+12V) - (-12V)}{\dfrac{R_2}{R_1 + R_2} (-12V) - (-12V)} \right) = 9.97ms.
$$

What am I doing wrong here?

simulate this circuit – Schematic created using CircuitLab

Without the \$R_i\$ resistor:

With the \$R_i\$ resistor:


texts: Are there any alternatives to ASIC chips?

texts: Are there any other mixed-signal integrated circuit embedded systems (or alternative solutions) which are faster than ASIC in terms of performance (let say for a high-efficiency Bitcoin miner)?


texts: Should I worry about EMC when building a PWM stepper motor driver with 1.5 meter cable?

texts:
I am building a board that would drive a stepper motor with PWM signal.
Is it likely that it will pass the EMC test?

Here are the details:
I am using Trinamic TMC5130 stepper motor driver chip.
The PWM frequency is 78.0 kHz
The board and the stepper are connected by 1.5 meter flat ribbon cable, (not shielded, not twisted).
The current through the stepper motor coils is up to 900mA.
Stepper coil resistance = 1.1 ohm, inductance = 2.6mH,
Power supply voltage = 12V.


texts: Wideband Amplifier and Coupling Capacitors

texts:
I am wondering how coupling capacitors limit the bandwidth of an amplifier like this and how to extend the bandwidth out to 2 Ghz. Will I have to add multiple capacitors to increase the bandwidth? If so, how do I determine the number of capacitors and their values

Text in book I got the design from: 'In practice, the very good overall performance of this amplifier can only be used in a comparatively small frequency band as the coupling capacitances Ci and Co cannot be given a wide-band low-resistance characteristic. If necessary, several capacitors with staggered resonant frequencies must be used.'


texts: What is the problem here, I used logic analyser to check the data and commands i send to the Ch376 USB Module, And all are right, But the module is not responding with any reply, Just return back the same data i send to the SPI register, I tried many connections to the module, Maybe there is a problem in the connection, Can any one help me to find out the problem, In the connection or the code?


texts:
Can anybody recommend a good resource/website for EXAMPLES of pic memory usage in C?  I'm having difficulty following all the TBLPTR/TBLRD stuff without seeing it used in lots of different, simple applications.  I'm surprised at how hard it is to find clear, BASIC examples of how to handle memory in PIC's.

Something like what a program would do with ADC results, storing in a table, choosing memory locations, etc.


texts: I bought a power adapter to my printer but the lable on it says output voltage is 32V at 1.56A that means it is going to deliver around 50 Watts to my printer. On the other hand the original adapter used to supply 20 Watts at 32V and 0.625A. my question is would the new adapter, supplying 50 Watts, break down my printer? Thank you


texts:
I found this solenoid on Sparkfun (https://www.sparkfun.com/datasheets/Robotics/ZHO-1364S-36A13.pdf) and according to the datasheet it is able to provide a force between 36N and 5N depending on the current travel position (see page 3).
I approximated this in an excel sheet, calculating the accelleration of a mass that is being pushed by the soleniod:
$$a=F/m$$
$$v^2=2*a*s$$
$$E_{kin}=1/2*m*v^2$$

Somehow, these values seem to be way too high when compared to an traditional, spring-loaded system where I would get around 3 Joule out of an 200N spring.
Is there an mistake in my calculation?
I have a feeling that it might have something to do with the speed the solenoid itself is moving.


texts: What's the cause of leaking voltage in this cable?

texts:
This is a 7x1 cable, made by some unknown company:

When I connect 220V to two of these wires, other wires also get ~60V. At first I thought I have some short circuit, there so I used a multimeter and checked all wires two by two and there was no short circuit.

How and why does voltage "leak" from two wires to other wires in this cable?


texts: In usb C to audio jack systems, is the DAC in the dongle or in the host?

texts:
I'd like to design my usb-c audio preamp, but that would be possible only if the analog audio comes directly from the phone, so that my piece of hardware can take the power supply from the usb-c and spit out an amplified version of that signal

I looked around the internet and found a lot of contrasting information.
Do the dongles receive a digital stream and convert it to analog audio, or are the dongles just a mechanical conversion between connectors and the dac is in the system (typically a phone)?

What is the industry standard practice?  What does the USB-IF say about audio via usb-c?  How an host can recognize when an analog output is required?


texts: Importance of ethernet connector and using a different connector with it

texts:
I'm working on designing a modular system where a custom camera has a mounting plate that screws on to a mounting plate on a robot. The camera gets power from the robot over springloaded pins built into the mounting plate that contact pads on the mounting plate of the robot. The camera uses ethernet to send video back, is it possible to use this same connection scheme, springloaded pins and pads, to connect the ethernet from the camera to the robot? The overall run of ethernet is <1 foot.
Thanks,


texts:
this could be most stupid question but i couldnt find where is the first pin:
http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-11157-32-bit-Cortex-M4-Microcontroller-SAM4E16-SAM4E8_Datasheet.pdf

there is circle which identify pin 1, but is the pin on left or bottom side ???


texts:
I am looking to move away from arduino, and start some projects using more feature-rich microcontrollers. I have been looking at the PIC18F4550 for its feature set, but I am shying away from the PIC products, mostly because I don't have a programmer, and the picKIT is a bit pricey ($50 for picKIT II, $70 for picKIT III). I haven't done as much research into AVR offerings, but I think I may want to. Here's what I'm looking for:

32+ Digital I/O pins
Programmable with minimal external hardware. Bonus points if I can leverage the usb chip on an arduino dev board, or my ftdi-usb cable to program it on the cheap.
Built in USB. This is one of the reasons I really was leaning toward the 18F4550. Is there a comparable AVR chip that has built in USB capabilities?
Good online resources- I would like to learn straight assembly, and it would be good if there were good resources online for learning assembly for my platform without having to read a 500 page datasheet.
Through hole mounting.
Minimal external circuitry to get running. An internal oscillator would be cool for fast prototyping, but I have no problem throwing a crystal in if I have to.

Anybody have any recommendations one way or the other?


texts:
So I'm awaiting to wire in one or two relays so that a circuit is not powered until a push button is pressed. Then the circuit remains powered until total power is turned off. I've been trying to figure out how.

This is to put in a kill switch into a car (factory starter button). Want to disable the clutch switch until the button is pressed but allowing the clutch switch to remain operational while the car is turned on.

Can you guys help?


texts: What are the addressing modes of these avr commands?

texts: What are the addressing modes of ldi, ld, and st. I think ldi is register direct, ld is register indirect, and st is also register indirect. Are those the right addressing modes?


texts: Problem in understanding how LM565 increases the VCO frequency

texts:
We were tinkering with an  LM565 (PLL IC) in school and I noticed that despite the fact that the maximum frequency of VCO was 3.5 kHz, I was able to use the PLL up to circa 5 kHz with the free running frequency of VCO set to 2 kHz.

Can someone please help me with understanding why this is possible? I think that if someone explains how the oscillator gets the additional current to go beyond 2 kHz (which was the free-running frequency of VCO,) then going even beyond 3.5 kHz should be self-explanatory.

In the attached schematic of LM565:

is a Gilbert cell phase detector - PHASE DETECTOR,
is bias current generator for current sources,
is amplifier - AMP,
is responsible for charging and discharging the timing capacitor,
is responsible for the measurement and amplification of capacitor voltage,
is responsible for controlling discharging of the cap,
is bias voltage generator for differential pair in upper 6, that triggers the (dis)charging process.

I see only one way of affecting the frequency (current through timing capacitor) – by the amplifier in block number 3 – the input of Q12.

I have trouble in understanding how Q12 may affect the current. Even the simulation of this circuit (mainly Q12) poses a challenge.

What do you think? Have I made a mistake in understanding this circuit? I am still a beginner, so please point out any mistakes in my reasoning that I have made :).

To achieve a 50% duty cycle at the output, charging and discharging the capacitor should take the same amount of time.

This is the internal diagram of LM565:

This is the schematic that we used to test LM565:

This is the LM565 datasheet


texts: Are all sequential circuits based on cross-coupled NAND or NOR gates?

texts: So far, all the sequential circuits I see in the textbook use cross-coupled NAND or NOR gates.  Is it possible to design a sequential circuit without them?


texts:
I am currently trying to route a micro strip for a GPS and GSM antenna on Altium which got some constraints on spacing with ground poured plane like the one shown just below:

This is currently my design below and I need to adapt it to try to match something in similar shape than what is just show above in my text.

I have calculated the parameter of W, T, S using polar software to respect impedance

Now I need to draw accordingly. I suppose I have to establish a rule but I don't know how to create it specifically only for this microstrip and not for the entire board.

Any help about how to acheive this will be very appreciated.


texts:
I have a Futaba radio with switch that can send 3 different PWM signals (1000, 1500, 200 multi state selection). I have been trying to use these signal for an on/off Video transmitter power source and gripper relay in the following manner:

->1000, state 0, both parts are off

->1500, state 1, Video transmitter power activate, gripper relay off

->2000, state 2, Video transmitter power activate, gripper relay on
I used an Arduino RC filter (4.7K, 100nf) to make different level of voltage (.2,2.5,5), also used a pair of IRF540 N-Mosfet. I have noticed the mosfet will be on when the analog line voltage is greater than 1 volt which is equal to 1100 band wide, hence I used a voltage divider in the way that output voltage always equal to mosfet Vgs, so for 1500 band wide (2.5 volt) need a 1k and a 2.7k resistor.

My question is whether this configuration can run a 500 mA device.


texts:
I am doing a project on self balancing quadcopter with Autonomous control. I am using Arduino Mega 2560 and MPU6050. I have obtained the roll and pitch angles from MPU6050 without the help of DMP and applied complementery filter to omit the noise due to vibration. Also Configured and able to run the BLDC motors with Flysky Transmitter and receiver with the help of arduino interrupts. Now for balancing I am focusing on only one axis(i.e. roll). I have also constructed a balancing stand for the free movement of roll axis by the motor.

For the controlling part, I am implementing PID algorithm. I tried using only the kp value so that, somehow I can balance and then move on to ki and kd term. But unfortunately, for Kp itself, the quadcopter is undergoing aggressive oscillation and is not settling at all.

Some of my queries are,

whether a single PID loop is enough, or we have to add another
what type of tuning method, i can implement, to find the kp, ki, kd
other than trial and error
I programmed my ESC for 1000 to 2000 microseconds. My PID input
angles will be within the range +/- 180. Whether I can directly set
the pid output limits for range -1000 to 1000 or -180 to 180 or any
other value.

The code can read from the url https://github.com/antonkewin/quadcopter/blob/master/quadpid.ino


texts:
I am currently trying to implement an inline TEDS adapter following IEEE1451.4 that can be used between an IEPE accelerometer and a Data Acquisition System. I prototyped what I think should work and the TEDS reader on the Data system is not recognizing the TEDS chip at all. A quick check using a prebuilt (Black Box) off the shelf solution shows that TEDS can be read through the two BNC's when inline between the transducer and DAS. I have also tested the TEDS chip themselves and can read/write when connected to separate standalone TEDS pins. I am wondering if there is something fundamental that I am missing or if I am way off the mark. Any help would be appreciated!
There is one unknown, the two diodes being used I believe are two 1N4148's but the markings on the body are CABJ4148. I've never seen one of those diodes not be marked with 1N. It tests out as a diode on a multimeter and LOOKS like a diode... could it be a different part? Thanks in advance for a nudge in the right direction!


texts: Power switching peripherial parts by MCU

texts:
Using an MCU like from MSP430 series, it is possible to create circuits that runs from battery power for years in some standby mode (waiting for button or realtime clock alarm for example).

However, if I for example add an OLED display, that has a specified 'sleep' power of 2mA, this wouldn't work.

How can I prevent the display consuming the battery power on standby? I first thought about switiching the display's GND by a MOSFET, but all other lines (data bus) may source current then, maybe the display even present VCC on the bus pins, if GND is disconnected? The display may source power from the bus pins then, draining the battery again or even destroying the MCU's outputs.

Is there a clean solution? Or do I have to find a display with equally low sleep consumption?


texts:
I am contemplating forward error correction on a vhf/audio modem link.  I am using 8b/10b encoding.  Its a little unclear to me where to begin if I want to use error correction.

To apply FEC with the 8b/10b encoding, would this typically start at the pre or post encoded level?

I have been searching for micro-controller targeted error correction libraries or code, haven't been able to come with much.


texts: Single Light switch to turn on/off based on computer program running

texts:
Brand new here so please be gentle lol Im interested in creating a light switch that turns on/off based on whether a computer program is running (Mac for now). I'm not entirely sure what components I need but think if I have that portion, I can take it from there.
So far, I'm thinking of connecting a USB-C to a (and this is the part I don't know) either to a microcontroller or to the switch itself. Not sure if that architecture will work. Later on, I'd want to have a wireless lighting device that will be controlled by bluetooth, most likely through a raspberry pi.
Any and all help/resources/suggestions/info would be greatly appreciated!


texts:
I am working on reception of IR signal from Air conditioner's remote. To achieve this I have selected IR receiver and sensor respectively - TSOP34438 and TSMP58000. The circuit diagram is shown below and the output of both sensors are fed to ESP-12E module's GPIO pins specifically GPIO14, GPIO12.

The issue with the circuitry is I am receiving an unstable performance i.e. not receiving stable output throughout a day without a change in circuit elements. I make sure the current supply for respective IR module is with the range specified in their datasheet. (Current supply: for TSOP34438 is 0.33mA and for TSMP58000 is 0.6mA).

The other concern is, without transmitting any IR signal, it is receiving environmental noise as an IR signal.

Can anyone help me resolve this issue?

I would appreciate your help. Thank you.


texts:
I'm trying to build some logic gates out of transistors to eventually be able to make a full adder circuit. I've tried building a NAND gate multiple times but I can't seem to be able to get it right. I've looked at lots of different pictures of them and all of them appear to have 3 resistors on them. I only ever put 2 in mine (R2 and R3 in this example) and I'm wondering whether my failures lie in not adding the third resistor (R1). I understand why R2 and R3 are there - to limit the current going from base to emmiter - however I don't understand why R1 is there.

So my question is why is R1 there and what is it's use in the circuit?

simulate this circuit – Schematic created using CircuitLab


texts: High power power regulators - thyristor regulator?

texts:
I am currently working on a system design that intends to control heating in different zones. All zones in total is calculated to use approx 340kW (230V). This will be divided into 11-12 smaller distributions. One distribution equals one zone, and each will maximum have 45kW.

The whole system will be controlled by a PLC and turn on/off the heating according to temperature, wind, humidity etc.

To regulate the effect of this I first thought of contactors, but I do not believe they will keep up in the long run (breaking due to too many cycles). I then came across the thyristor regulator, and as I have no experience with this, I wonder if it's the right thing in this setting? Even so, how long could I expect this component to last?

The system is designed for harsh enviroments and must be able to run with little/no service.


texts: Some questions about MOSFET power, temperature and LTspice

texts:
A MOSFET transistor IRF530 is dissipating a pulse like power curve(green plot below) for around a second during its switch-off(red and blue are voltage and current):

(left-click to enlarge)

And here closer look:

This MOSFET is not manufactured to be used in linear region but  for some reasons I have to use it this way even though it switches off slow.

I have asked a related question before here: A question about heating of a slowly turning off MOSFET
and I'm sure the answers were great and clear for many but unfortunately there are some confusing points that I still couldn't grasp.

That previous question of mine led me to believe that I wasn't able to interpret this bell-shaped power pulse(green plot) when using a data-sheet.

As you see, during transition this power in linear region makes a peak to around 30W and decreases with the same rate and the whole event takes a second or a bit more.
It is not periodic(not repeating, only one single pulse), or should I say the period is infinity.
In this case if I take the period infinity the average power goes to zero. But if I take the average across the 1 sec transient time the average power becomes around 15W.
So depending on the integration interval we get different average powers. As you know LTspice calculates and shows this average power for the selected time interval automatically and you can see that average in my above plots as well.

After this short introduction, let me explain my confusion:

I have been trying to find answers to the following two questions for the last week without any achievement:

1-) Remembering that this is a single bellshaped transient(not a periodic) and is not exaclty a typical square pulse mentioned like in the data-sheets:
If I want to use this MOSFET's power dissipation and use this power to check anything with the data sheet which power should I use?
Average power or peak power? If average power, what should be the integral interval?
I currently calculate the heatsink by considering the power dissipation as 15W even it is a single pulse.
And if I take the average through 1 sec and say the MOSFET dissipates 15W average,
then how will it fit to the SOA graph? The bell shaped power pulse should be considered as a 15W power for 1 second pulse width? I hope I made this one clear enough, pardon my english.

2-) I found out that LTspice has a new feature which can simulate the temperature of an nMOSFET called: SOAtherm which can also be used with SOAtherm-Heatsink.

Here is the information about it:

"Modeling Safe Operating Area Behavior of N-channel MOSFETs" at: http://www.linear.com/solutions/5239
And here is the video how to use this feature: http://www.linear.com/solutions/5445

It seems they only have this option for some MOSFET models(not for IRF530) but they also have a "User defined" option which makes me to think one can add any MOSFET?

When I look into their library SOAtherm-NMOS.lib for each MSOFET the SPICE code starts as for example:

.subckt BSC009NE2LS D G S D2 G2 S2 Tj Tc

* The following two lines are customized for each  model *
.param Tambient=85 RthetaJA=50 Cheatsink=0
.param Imult=1.00E+01 Iexponent=3.00E-01 R6=3.18E-02 C6=1.77E-04 R5=1.01E-01  C5=2.77E-04 R4=2.74E-01  C4=1.60E-03 R3=8.49E-01  C3=8.83E-03 R2=7.34E-02  C2=3.30E-03 R1=1.05E-03  C1=1.82E-03

* The remaining lines do not change between models
... the rest of the code same for all MOSFETs...

It means one can modify couple of lines for a custom model.
I wanted to do the same thing for IRF530 but what are these parameters I couldnt figure out. I only know RthetaJA from data-sheet but have no idea what are C1 C2 R1 R2 ect...

Has anybody dealt with this tool and know how to customize? I've sent an email and asked about this to them but didn't receive any reply after a week.

In their web-site there is great explanation about how to use this tool but no info at all about how to customize.


texts: What are sheath and armour loss in underground cables?How can these be prevented?


texts:
I just started sketching a simple PCB for LEDs with integrated drivers, it has large unused spaces and being lightweight is important, so I was considering milling holes in the middle of these empty spaces. Would these cause any unwanted loops or noise problems? Max current would be 60mA per LED and 16 LEDs per board.

Traces positions/width were just to start the sketch and are not final.


texts: How to detect input voltage change on specific pin of atmega32? DC jack sensing

texts:
I am trying to make an LCD circuit that, eventually, will control an amplifier and display data to the user through the LCD. One of the features I want to include is the ability to show if the device is plugged via an AC wall adapter, or just a 9V battery. The circuit below is what I have so far. Everything is tested working on the bread-board except for the DC sensing jack.

Here is my circuit:

I am very new to the whole MCU programming thing, so I want to make sure I am on the right track. When I go to the program, will I be able to use pin 29, PC7, on port C to detect the change on my DC in port?

JP2 is the 9V while DC-IN is the wall adapter jack. Pins 2 and 3 are normally closed.

Basically, I want to detect when the user plugs in the DC adapter so I can change an icon on the LCD. When the user plugs in a wall adapter 2-3 on the DC-IN opens and PC7 will no longer have a connection to ground. (if I understand things correctly) That way I should be able to use PC7 to detect a change in R2, the pull-down resistor?

Basically, I still want to use PC0 through PC6 for other I/O stuff like led control and button press detection. I want to make sure that, programmatically, this is possible. That way I can continue my design knowing I can get things working.


texts: Understanding 3 phase 480V lighting circuit

texts:
I understand that you would use 480V light fixtures as opposed to 277V because the 480V have a lower current draw, resulting in a more efficient system. What I don't understand is how this circuit works. In the following paragraphs, I'm using the term "supply" as current flowing to the load and "return" as current flowing back to the breaker panel.

In a simple single-phase lighting circuit, you would have two wires: say, 120V hot wire and a neutral wire. Current flows from the hot to the light fixture and back through the neutral, assuming conventional direction of current flow. This completes the circuit and you can calculate the wattage by measuring the current pulled and the voltage supplied.

However, I don't see a 3 phase lighting circuit with 480V light fixtures work like that. Consider a 3 ph system A, B and C. If the A and B phase are connected to the fixture in a "480V single phase" manner, which phase supplies and which one returns current? If A supplies and B returns, then what about a load that's connected across B and C? That would mean C supplies and B is the one carrying the return current at all times, or else you will have a conductor with two currents flowing in opposite directions.

OR is the fixture drawing current from both phases? If so, then that's not single phase. Also, wouldn't you use 3 single-pole breakers as opposed to 1 3-pole breaker to supply the 3 phases. Please advise.


texts: Is Stepping Down More Efficient When Voltages are Already Closer Together?

texts: If I was to use a buck converter to step-down my input voltage would I have a greater efficiency if my voltages are close together e.g. 7.2v to 5v compared to 12v to 5v?


texts: Voltage divider with a short, what is Vout?

texts:
Figure 1:

            A                 B
Vin---====-----====--+--====-----GND
       R1       R2   |   R3
                     |
                    Vout

In this basic voltage divider, \$V_{out}\$ is calculated as:

$$V_{out} = \frac{R3}{R1 + R2 + R3} \times V_{in}$$

Figure 2:

            A                 B
            +-----------------+
Vin---====--+--====--+--====--+--GND
       R1       R2   |   R3
                     |
                    Vout

In Figure 2, a short is made between points A and B.

Will there be a voltage at \$V_{out}\$?

If so, how is it calculated?

EDIT:  A follow-up to this question is posted here: Voltage divider with short circuit part 2


texts:
As we know that for the transistor to operate in the active mode, it should have emitter-base junction as forward bias and collector base junction as reverse bias. So the common-collector configuration should also follow the same rule. Below is a diagram:-

In the above diagram we can see that Emitter base junction is forward-biased since |Vee|>|Vbb|, that's fine. But you can see that the base collector junction is also forward-biased (where it should be reverse-biased if it is in active mode) in both pnp and npn transistors. Please help me here, it has been a confusion for me since 1 month. I really want to understand it here. Please give me a descriptive answer.


texts: How can I reduce the power dissipated across this MOSFET without affecting avalanche?

texts:
previous and very relevant question here. I want to reduce or remove entirely the heatsink that is attached to my switching MOSFET. It heats up due to the back-EMF generated by the large inductor that it switches on/off. I can't use a freewheeling diode as I need the current drop-off and subsequent avalanche to happen as quickly as possible. This is the circuit and the expected voltage and current generated:

Zooming in on this you can see that switching voltage is 12V:

As you can see, vn006 is the voltage across the inductor that stays at 12V for a period of 50us and then switches off. This causes a large back-EMF of a few hundred volts. I(L1)is the current within the coil, it slowly increases as the FET is on and then sharply drops when the FET is off. The circuit in this configuration works perfectly but the issue is that the FET requires a large heatsink.
In the answer to the linked previous question it was suggested to make an LC series resonant circuit, where at the end of the resonance half-period, voltage on the capacitor is back to zero and current in the inductor has reversed direction. The FET's body diode turns on, and the energy stored in the inductor returns back to the power supply. But adding a capacitor between the inductor and ground just causes oscillations and completely removes the back-EMF. What am I doing wrong here?:

Adding a small value resistor in parallel with the cap will remove a lot of these issues, but then isn't that making the addition of the cap redundant? Any pointers would be greatly appreciated. In addition I would like to keep the high-side switch if possible.


texts: Is the maximum rated current of the cable the same for any voltage?

texts:
Cat5e cable has a rated current of 0.577A (wiki page). I am wondering if this is voltage dependent? I am almost certain it is not, but if it is, something might blow up. Say I need to get 2A at 5V across the cable. I boost it to 24V / 0.5A, send it across the wire, and step it down to back to 5V and a bit under 2A. Would that work? If the cable is proper Cat5e could I do this trick with up to 100V as long as I don't exceed 0.577A?

I am worried if the cable heats up at near maximum rated current, for instance, the safe voltage could drop as the insulation softens up or something. I will certainly test this, but I wonder if there is some rule that I don't know about.


texts: Is it a good idea to make a second DC installation in a car with its negative separate from the car body?

texts:
Normally in a car's DC installation the negative is on the car's body. Is it just to make it cheaper by not having to provide two wires everywhere, but just one and use the car body as negative, or is there another more important reason it is done that way?

I ask, because I want to make a secondary DC installation in the car, with another battery, different voltage, to be used for my electronics, computers, etc. The second installation will have a separate battery, but that battery will be charged off the main installation - not directly, but through a charge controller, basically a DC-to-DC converter with current limit, which will have separate positive and negative terminals for both input and output.

How do you recommend to wire the negative of this secondary DC circuit, should I keep it separate, isolated from the car body, or should I also connect its negative wire to the car body, so use a common ground for both installations?


texts: Trouble understanding when voltages get split

texts: I am having trouble solving this Op-Amp problem. I'm looking for Vo, and am confused as what to do with the 9V supply and the 2k and 6k resistors. Would the 9V be split between these two resistors? Also, when doing KCL for the V- value, should I include the current from Vo over the 4k resistor in the KCL equation? I feel like I'm right on the cusp of understanding with this one...


texts: Should I add an undervoltage protection for lithium battery-powered projects?

texts:
I am designing a board with a microcontroller (an ESP32) that will be in deep sleep most of the time. The board will run on a 1-cell lithium battery (not sure if I will use a Li-poly or a Li-ion).

While looking at existing design schematics (Adafruit HUZZAH32, SparkFun Thing Plus, DFRobot FireBeetle), I was shocked that these products doesn't integrate an under-voltage protection (or I missed it?) to stop the board from drawing any current below a threshold voltage.

Is it safe to do so? Is the under-voltage protection not required because most of the batteries have a built-in circuit for that? Also, is it possible to add under-voltage protection without adding BOM costs (e.g. using the STAT pin of the charge controller to drive the ENABLE pin of the regulator)?


texts: LTspice default rising/falling times of pulse edges

texts:
Above is how I set up a pulse in LTspice.

When I set the rising and falling edges as zero or if I do not register any value, in that case LTspice automatically sets the rising and falling edge duration. In above case it is 25ms for a 2Hz pulse. So if I want a very sharp pulse I have to each time type something like 0.0000001 instead of 0.

Can there be a reason for this default settings or is this a bug?


texts: Need to block a 2Hz signal to a simple inverter

texts:
I have to create a circuit to handle a signal that can be in one of three states:

high (3V)

low

2Hz square wave

The logic needs to be...

----------------
|  IN   |  OUT |
----------------
| high  | low  |
| low   | high |
| 2Hz   | high |
----------------

I have a nice simple circuit that covers the first two well, (simple inverter), but cant see any simple way to handle this 2Hz signal.

If possible, I need to do this discretely, without any ICs.


texts:
I am trying to find the current through the inductor in this circuit. When I approach it, I get a differential equation that does not seem like something I've learned how to solve. Am I making a mistake somewhere? Is there another approach that gets me a simpler differential equation to solve?

Here are my steps:

I use current distribution.

Then I get this. It is a differential equation where the coefficient of y' is y.

Edit: Ignore the text in parenthesis: the voltage source turns on at t = 0


texts:
I'm looking to try and get guitar notes played in real time. My q is whether it's possible to do this from one end of the string to minimize adding stuff onto the guitar. If this is possible with an arduino that would be ideal.

Lisa


texts: What thickness of wire should be used to power Arduino on 9 meters?

texts:
I have built a standalone Arduino device which has a few buttons, LED's and one servo. I also have a power source which on the casing says 4.9VDC ~ 700mA. (Actual reading is 5.7V). This power source worked for a whole year non-stop powering my Arduino UNO at 9 meter length with two solid core wires. [See below.]
Now I built this device to be standalone and also to use a more neat wire. If I use the dual-wire the device gets powered, but malfunctions. If I connect the device directly to the source and skip the extension, it works fine - this brings me to the conclusion that is in fact the wire. The voltage on the other side of the extension seems normal, so I guess it is the current that drops to below required?
What type or sort of wire can I use to prevent to much power loss and to power my device at 9 meters? - obviously as thin and neat as possible.
UPDATE
I investigated the "malfunctioning" and it seems as if the board resets the every time when the servo moves. As if the servo is draining the current or if the servo causes a major voltage drop.
Voltage on both wires are the same on the end as at the source without anything connected and with the device running (without the servo moving).
The Power source:

The old but working solid core wire:

The new but not working dual wire:


texts: How is the trigger pulse of the 555 timers generated?

texts:
I would like to connect an operational amplifier to the trigger circuit which then generates the pulse that starts the timing of the timer almost always connected to the clock generator.
Since 555 should consist of 23 transistors I think 2 capacitors if I remember well, I would like to understand, if I wanted to create a personal one, how the operational should be connected to the circuit of the trigger (trigger circuit is a part of 555 timer) because I'm not much interested to timing but the pulse signal that the trigger generates for timer, it is more on the impulse I would like to act on.


texts: How to test a TRIAC with just a digital multimeter and no external circuit

texts:
I need to fix an electric kettle and would like to test the health of the TRIAC BTA20. How would you test this component health with a digital multimeter - without any extra components and ideally without removing it from the circuit?

thanks,


texts: Why starting current in star-delta starter becomes 1/√3 times that of DOL starter?

texts: I have seen this statement in a question paper. I was asked to prove it but I can not find the logic.


texts: What "mode" is static electricity (lightning?) Is it common-mode, differential-mode? It seems half-way, or "mono"

texts:
The common-mode or differential-mode designations assume two conductors, one in-phase, the other anti-phase, but a static circuit is different because the "conductor" is concentrated in thin lines during discharge, but distributed (and delayed) during the return, so it's as if the signal is just "mono" and neither common-mode, or differential-mode.
The common-mode choke is used to protect against common-mode noise which comes in both lines with the same polarity and amplitude, and can then oppose each other when trying to energize the magnetics of common-mode choke.
I understand that, in addition to common-mode noise, there is another kind of noise called differential-mode noise, which I assume goes in one line and back out the other, with equal and opposite polarity, which I would assume would be similar to the signal in one twisted-pair of an ethernet cable. But that's a desired signal. There are obviously other differential-mode energies that can be thrust upon a pair of conductors that are not-desired, where the energy goes out one wire and comes back in another wire (though I'm not sure what this typically is).
Static electricity is also different because the voltage is so much higher, creating a circumstance where it comes in only one of the conductors, so it is therefore neither common-mode nor differential-mode, but some kind of half-differential mode (or mono mode). Each line having its own choke (in my mind) would be a way to protect against this. But I hadn't heard about a third mode, where the return for the circuit would be outside of the device and not coming back on any conductor. Would you please tell me the name of this "third" mode, and a little bit about it? Thanks.


texts: Is there a circuit that will take power from two sources and would use the second only if the first is down?

texts: I'm looking for a specific circuit that would be connected to 2 power supplies. However, unless the first one fails e.g. power outage, the second one will not be used. I'm not familiar with the name of such a circuit to begin with. Would there be off-the-shelf products designed for this purpose? If not, how can I design one?


texts: Looking for Connection Ideas for 12V Battery Pack

texts:
I'm working on a project that's requiring the use of a battery pack made from 18650s. 3 of them in series connected to a BMS. It's a 12V supply that is housed in a 3D printed part, length wise of the batteries, like a hot dog. I haven't had much luck in trying to find a terminals similar to what might be seen on a laptop battery, camera batteries, etc. When searching all I can seem to find are either car battery terminals, or the basic ring or spade terminals you'd find in an assortment kit.

Originally, I was using a DC female/male jack, but do to space limitations I'm not going to be able to fit that in the design. If I can charge/discharge through a single port, great. If not, I figure I'll need wire something similar to a portable phone charger's layout.

Any ideas on what to use or any resources where I could browse these types of connections? The smaller the better.


texts: How can I make a linearly tunable 50% duty astable multivibrator?

texts:
I want to make an astable multivibrator with a 50% duty cycle that can be tuned with a potentiometer for generating sound, so accuracy is desired.

My first thought was to build the standard one with transistors, but that requires 2 resistors that control the mark and space separately.

Second thought was to use a 555 timer. I made the below circuit with a pot for R3. The circuit claims to have a 50% duty cycle and a frequency of 1.4/RC. Except it satisfies neither of those claims.

It only has 50% when Vout=Vcc, which is not the case. This thing does not go rail-to-rail. It's also not linear. If I halve the resistance, the frequency is less than doubled.

So the question is if there is such a circuit that truly has a 50% duty cycle and where the frequency is linearly dependant on the RC time? where frequency closely matches \$f=\frac{k}{RC}\$

[edit] To clarify what I meant by linear. Any sort of sensible/relevant/simple relation between resistance and frequency will do. But I was thinking of something that actually does \$f=\frac{1}{RC}\$.

The point is that I want to connect multiple potmeters with buttons to make sort of a keyboard. Now if you press 2 buttons you get parallel resistance. I'm hoping that those parallel resistances will turn out to be nice harmonics. This is why I mentioned that 2 buttons of the same resistance don't quite make an octave(double frequency) with the 555 circuit.

[edit2] I'll put some values for the relaxation oscillator here, which is expected to do \$f=\frac{k}{RC}\$, but just like the above 555 circuit this does not seem to be the case. \$C=10^{-6}\$

R=4.01k, f=136
R=3.13k, f=191
R=2.05k, f=290
R=1.30k, f=452
R=0.95k, f=602
R=0.56k, f=915
R=0.26k, f=1547

[edit3]
The Schmitt trigger + integrator circuit proposed by Andy Aka displays similar behaviour to all the others, where 2 resistances tuned to 400Hz in parallel only give 754Hz, two times 200Hz gives 392Hz. this was the main issue with the 555 circuit


texts: Why parallel LC oscillator producing very high voltage?

texts: I was trying to generate 1 MHZ frequency using LC parallel circuit using 2.53 mH inductor and 0.01 nF capacitor and I successfully did so. But its amplitude in KVs is surprising me. Any idea why?


texts: LED color changing circuit using power cycle

texts:
I'm trying to design an LED circuit for a model that will allow me to change the color of a bi-color LED each time the power is cycled.  In other words:

Power off:  Nothing
Power on:  Green
Power off:  Nothing
Power on:  Red
Power off:  Nothing
Power on:  Nothing
Power off:  Nothing
Power on: Green, etc. etc.

Or, if the green/red/off/green... cannot work, can I do a green/red/green/red... instead.   I'm NOT looking for flashing, but a steady light that only changes color when the power is cycled (off-on).  No components have been purchased, but would like to do this with 3mm or smaller two-color LEDs.  My skill level is beginner/intermediate, so the simpler the better.  And of course, if I'm barking up the wrong tree, let me know.


texts:
This might be more of a math question but when solving electrical circuit problems, if f(x-1)= x
What is f(x)?


texts: Read/calculate permebility from BH curve

texts: I need to find the permeability from a non-linear BH curve. B is given in mT. and H in A/m.


texts:
I'm using a PIC16LF1554 with a simple soil moisture sensor to remotely monitor houseplants. The sensor circuit will be powered by a coin cell and will spend most of its time asleep. It will wake periodically (maybe three times daily) to take a reading via ADC, transmit to an always-on master via nRF24l01+ and then go back to sleep. This is a hobby/learning project, not a commercial enterprise.

My question is about minimising current consumption in sleep mode, about which the datasheet says:

  To minimize current consumption, the following conditions should be
  considered:

  I/O pins should not be floating
  External circuitry sinking current from I/O pins
  External circuitry sourcing current from I/O pins
  Current draw from pins with internal weak pull-ups
  Modules using 31 kHz LFINTOSC

I'm comfortable with all but the first item, but I have a number of I/O pins that I'm not using, so I've not connected them to anything in the PCB I've designed (maybe that was stupid). The datasheet goes on to say:

  I/O pins that are high-impedance inputs should be pulled to
  VDD or VSS externally to avoid switching
  currents used by floating inputs.

So, my question. Is it ok to configure my unconnected I/O pins as outputs and set them LOW (or HIGH)? Would that result in any unnecessary current draw?


texts: Creating ladder PLC logic using force inputs and outputs

texts:
I am currently using Allen Bradley PLC and  RSLogix Micro to program it. The problem is:

Create a ladder logic diagram for the following problem in which pump #1 and pump #2, alternately or
simultaneously, pump liquid.

• When the level switch closes, first pump #1 turns on. If pump #1 runs more than 30 seconds, then
pump #2 turns on. Both pumps continue operating until the level switch opens, indicating a lower
liquid level.

• When the level switch closes again, pump #2 turns on. Note that either pump #1 or pump #2 will
turn on first to discharge the liquid. Similarly, if pump #2 runs more than 30 seconds, then pump #1
turns on. Both pumps continue operating until the level switch opens, indicating a lower liquid level.
Therefore, either pump #1 or pump #2 discharges the liquid, or both pumps discharge the liquid.

Use the force function to close and open the level switch and turn the pumps on accordingly to
discharge the liquid level.

Use the force function to turn off (i.e., disable) one of the pumps. Now, run the program and
examine if it is working properly.

The updated solution:

The question is that I am not sure if I understand the alternating process between the two pumps.

3rd attempt: The first part of the problem.

4th attempt: So I tried to insert the "flip-flop". And I understand that XOR command is used to alternatively change the value of the B3:0/1. However, when I tried to put in RS Logix the program that you provided, I could not write the address B:3.0/1. Because, it said that address should be specified to the word level. And also the BSR command is represented different in RS Logix. Is represented as in the picture below:

Assuming that the flip flop is working and the values are changing alternately I wrote the program.

Thank you so much!
5th attempt: This time the program worked. And the pumps where energized alternatively.


texts: Atmel ice Connection Issue with "device signature"

texts:
I have recently got a atmel ice and am having trouble programming it. I have been trying to connect it a attiny2313-PU. I am confident that I have wired it up correctly. The problem is when I look for the device signature I will get an error of

"Failed to enter programming mode. ispEnterProgMode: Error status received: Got 0xc0, expected 0x00 (Command has failed to execute on the tool)

Unable to enter programming mode. Verify device selection, interface settings, target power, security bit, and connections to the target device."

I dont think it is a fuse problem as I cant access any fues in debug or isp mode. If you guys have any ideas that would be helpful.


texts:
I need to power my device with three different voltages: 3.3V, 5V and 12V. I already have a 12V 1A power supply. So my questions are:

Can I use the circuit below to get these three voltages?
Is it safe when ground of LM317's is shared?
Do I need any additional diodes or anything else?

simulate this circuit – Schematic created using CircuitLab


texts: Why not use a diode instead of a resistor for current sense circuits?

texts:
We're building a motor-drive circuit using an L6206 dual H-bridge circuit. The bottom side of its H drivers come out of a pin called \$V_{sense}\$, intended to be connected to ground or to a low-side current-sense circuit. I'm expecting to drive motors with PWM up to an amp or two.

I want a logic sense line to indicate whether there's any current flowing (say \$>10mA\$), or not. It's essentially detecting the operating presence of the (removable) motor.

I think I can do this by comparing the voltage drop across a Schottky diode with an approx \$0.25V\$ reference. I'm thinking of using a divider to create a weak \$0.25V\$ voltage source from my \$5V\$ power supply, a \$2A\$ Schottky diode (eg SB240, \$V_f=0.5V\$ at \$2A\$) with a small \$25\Omega\$ bypass resistor to eat any leakage, and a comparator (eg LM324 op-amp, or LM339) to create the \$5V\$ logic result.

simulate this circuit – Schematic created using CircuitLab

Wherever I have looked up designing current sense circuits, there is always a low-value power resistor to create the voltage drop. I haven't found any that use a diode. I think that a Schottky diode is perfect: its voltage drop will clamp off nicely so it won't waste heat, it's cheap and simple.

Perhaps everyone else is interested in measuring the current level, where I just want to know if there is a current at all? Or, they only care about being close to a maximum current, where I want a minimum?

Why don't I see any diode-based current sensors?

Note: my logic output essentially goes into a latch, so I don't care that the signal will flap around with the PWM.


texts:
I've not yet used a RTC so I'm not completely sure of the "normal" way to read a real time clock. There's a few different approaches I've thought of but was hoping for some advice on it.

Here are the ways I've thought of reading and using the time so far:

Get the date and time at power up and save to RAM, and then through the use of the timer interrupt increment the RAM values every second etc. The code would then use the values in RAM whenever it needed to know the date/time.
Through the use of a timer interrupt, query the RTC every second and copy the received date and time to RAM. Again, the code would then use the values in RAM whenever it needed to know the date/time.
Every time I need to find out the time, query the RTC and use it's response directly.

Which would be the best approach?


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I used the spice language to build an integrator op-amp, and one of the questions I had to address is to run an AC analysis on it.
long story short- by looking at the transfer function of an integrator, I imagined I would get a negative voltage, but I got a positive one. Someone explained that since it's AC measurement, it only measures the amplitude and thus I don't need to actually get negative values. Can you please explain why this is true? thanks!


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I am required to transmit a standard Hex payload through serial com port to a device that has a CAN transceiver. The serial configuration is as follows: 500 kbps, 1, 8, None, 1.
The DUT has a CAN transceiver which only expects the Hex Payload and not a standard CAN frame. The Hex Payload contains it's own ID and CRC. I was wondering if there is an adapter module available that would allow me to send the Serial Data vi com port so I can communicate with the DUT.
I tried to communicate with the DUT using a standard CAN Frame (using NI8502 CAN module) and my DUT does not respond as it receives a lot of unnecessary data through CAN Frame.


texts: Why this optoisolator triac (MOC3021) using for DC/DC switching is not turing off?

texts:
I'm using an optoisolator triac (MOC3021) for switching a DC12V coil Relay.
optoisolator triac Input is a digital 2.5V signal connected with a 68ohm series resistor.
Isolator Load vlotage is 12V and about 30mA (normal coil relay).

when the signal is "ON" (+2.5V) the optoisolator is triggered and and it also trigger Relay But when the signal is go "OFF" the Relay Stay ON continuously.

I have disconnected the Isolator signal completely, nothing changed.
relay stays ON until I disconnect 12V power.
when I reconnect it All, the relay an triac is off until 2.5V signal activated and again the triac and relay stay continuously ON.

simulate this circuit – Schematic created using CircuitLab


texts: op amp+mosfet = current source.Why do we need a feedback resistor?

texts:
The feedback resistor is needed to compensate for the error of the input currents? How to choose the resistance R2.

Circuit source

Resistor R2.

Can I use this circuit, op-amp with differential input voltage range = +/- 0.6V? I'm not sure. I think not