texts: How to determine how much energy recovered from regenerative braking

texts: I am considering a regenerative braking system implemented with a AC permeant magnet motor with an efficiently of ~96%. It is easy to determine via energy equations the kinetic energy of the car and therefore how much energy is possible at max efficiently but regenerative systems also rely on the brakes of the car to slow it down to a stop. Is there a particular rule or reference to how much conventional braking is required for a given scenario? I wonder if it is possible to determine how much the motor would actually decelerate the car and then work out energies from there. Could anyone offer some advice?


texts: Switching between battery and transformer

texts:
I want when power goes off my device don't lose power and keep working using battery power, the schematic below is what i end up with:

simulate this circuit – Schematic created using CircuitLab

When power is ON transformer trigger the relay and device will use transformer power, when power is OFF relay will "de-energized" and device will use battery power.

What options do we have to switch between transformer and battery in case of power loss which is simple and easy to do?


texts: AC to DC Bridge Rectifier DC Amperage Drop

texts: Assuming I used a 120 VAC -> 12 Vac 2 VA transformer and pass the current through a full wave rectifier circuit what is the maximum amperage I could draw on the DC side.


texts: How efficient is wireless electricity compared to wired electricity?

texts:
I am looking for data showing practical data/information on the efficiency of wireless (induction) transfer of electricity vs. wired transfer. There is some information out there but the source makes me hesitate at taking this at face value.

Assuming standard US mains power (120 V AC), charging an iPhone 5S battery (3.8 V 5.92 W·h (1560 mA·h)) from 0% to 100%, how many Watt-hours would be consumed from a standard wired connection vs. a non-standard wired connection?

If we take the presentation linked above at face value, and we work backwards, we would get:

Wired (best case): 5.92 / 85% / 90% / 90% / 95% = 9.05 Watt-hours (65.4% efficiency)
Wired (worst case): 5.92 / 85% / 80% / 80% / 95% = 11.46 Watt-hours (51.6% efficiency)
Wireless (best case): 5.92 / 85% / 89% / 89% / 95% / 80% = 11.57 (51.1% efficiency)
Wireless (worst case): 5.92 / 85% / 89% / 89% / 95% / 60% = 15.32 (38.3% efficiency)

Yet the conclusion of the presentation is:

The improvement over the standard charger seems to be based on the assumption that the efficiency of the device will improve if the charger is integrated in to the wireless receiver.

At the end of the day, what is the actual efficiency of a wired charger vs. a wireless charger? Can the wireless charger actually be an improvement in efficiency over a wired charger for things like charging an iPhone, or is it strictly a convenience-based change?


texts: Is it advisable to use lead-free PCB and solder paste on a first SMD assembly job?

texts:
I am sending my first PCB design to Sunstone for manufacture and I need to decide whether to order the board finish lead-free. All of the components are lead-free, and I have not decided on solder paste. There are about 25 chips on the board and the smallest are 0803 and SOT143. The board size is 3.0x1.5 inches. I am planning to order a cheap IR reflow oven like the T962A. This is not a consumer product (it's a driver board for an IR laser used in scientific experiments). I understand that lead-free solder doesn't flow as nicely and requires higher temps, etc. Shoud I Go Green or should the additional usage complexity dissuade me from using lead-free?

Followup question: should I order a stencil for a board like this?


texts: Demagnetization of pulse transformer megnetizing inductance

texts:
Here I am caculating the power dissipation in the primary of pulse transformer. The transformer has very small secondary current hence primary and secondary current are ignored.

My question is when voltage pulse (Vin) of 3 volts appers across the transformer, does current (Ilm) rises linearly during on time and current decreases linearly during off time as shown in the diagram?

Is the represenation of current (Ilm) waveform correct in the image?

Linear increase and decrese of slope ideally has to be same?

Thanks in advance.


texts:
I would like to know please if there is a way I can run a LTspice simulation using only python.
In other words, I need a python alternative to this command: subprocess.run(['scad3.exe','-b','netlist.cir']). I know there is an ltspice library but, to my knowledge, it is only used to extract data from the generated .raw file but does not run the simulation.
Looking forward to your suggestions.


texts: Forgot ICSP / in-circuit interfacing of pins on Atmega328P in TQFP-32 package

texts:
I am having an issue due to my own stupidity: I designed a PCB with the good old Atmega328P in TQFP-32 package. I broke out the pins for UART in  order to be able to Arduino-flash it (beginners/students will have to work with this board, which is why we thought Arduino IDE is the best option). However, I somehow  forgot to break-out the ICSP / SPI-pins that I'd need for flashing the bootloader.

Unfortunately, they are currently all connected only to 0603-components, which makes soldering jumper wires to them tricky (I did it, one ripped off quickly including the pad). I could probably get it to work this way, but I have 7 of these boards and asked myself, if no-one else was ever that stupid and came up  with a nice in-circuit IC adaptor or another good solution - I was thinking, something with pogo-pins and a fixture...

Any comments, has this happened to you before, and how did you deal with it?


texts: How do I fill a SystemVerilog Queue variable?

texts:
module queues;
int a[$];

int i = 100;

initial begin
    foreach(a[i]) a[i] = i;
    foreach(a[i]) $display("\tValue of a[%0d]=%0d",i,a[i]);
end
endmodule

I have my unbounded queue 'a'. I have to fill > 150 locations with random data. I have to use (push/pop/positional) constructs as well. I am trying to fill some of the positions using for/foreach loop, but it's not working.

Error msg: XXXX: I don't know how to handle expr_type=9 here error:
Code generation had 1 error(s).

Where am I wrong? And what do you suggest to do in this problem statement?


texts: Operational amplifier and negative feedback

texts:
Let's consider an op-amp. In every book I've read till now, it is said that if we have:

negative feedback
finite output

then we have:

Vout = A * (v2 - v1)  -->  (v2 - v1) = Vout / A

If A is very very large, then v1 and v2 tend to be equal (although they are not equal)

Now the question: who says that at the very beginning (that is, when the circuit switches on), the difference between v2 and v1 is so small that we are allowed to use the linear region shown in image b (thus justifying the previous calculation)? What about if at the beginning (v2-v1) is not so small?

Thanks


texts: How to supply enough power for a DC motor

texts:
I'm fairly new to electronics and have been reading extensively into it, but I'm unable to map all the concepts together.
My project is a tiny drone involving (four) 4 N40 DC motors, rated 26k RPM at 3V 0.3A, and 42k RPM at 6v 1.68A.

From my understanding, to power the motors at full capacity, I need to provide ~10 Wh, that is (1680)mAh * (6)V = 10.08 Wh each.

I have a set of 3.7V 1,000mAh batteries (3.7Wh), thus I would need four batteries where each two are connected in parallel and then the the circuit is eventually connected in series providing a total of 7.4V and 2Ah or 14.8Wh.

Theoretically, to provide 40Wh to all four engines, I would need to provide total of 7 pairs (14 in total) of batteries connected in parallel to provide 7.4V at 7A leaving me with a bit excess of power. Is my understanding correct as that seems to be a bit excessive?


texts: Regulator Getting Hot. Is The Mosfet Driver At Fault?

texts:
i am using a TC4424 mosfet driver which has a peak output current of 3A driving a irl3705 mosfet(which is driving a 400mA load),
The mosfet driver along with rest of the circuit is being powered by a 5V voltage regulator (CW7805) which at max can dissipate (( 12V Supply -5V Output)x 1.5A Max Current)=10.5 Watts.
The mosfet driver is being given a signal via an esp32 gpio pin.
The problem is that the regulator is getting hot even with a 2.1x2.5cm heatsink and a fan. From my calculation the total circuit current consumption is around 1.2 Amps excluding the mosfet driver consumption.
Is mosfet driver consuming a large amount of current to drive the mosfet?. Can i connect the mosfet gate directly to the esp32 pin so that i could lower the current consumption?


texts: how amperage of the source influences the components of a circuit?

texts:
I am trying to understand when some devices say that for example it needs 5V and 2a to work properly, or when a USB charger says it provides 5V at 1A or another that says 5V at 2A.
Why does all this mention the source current? isn't the source supposed to only provide voltage and the current is defined by the resistance of whatever im connecting to the source?
So for example, if I have a resistor to heat a blanket or whatever at 10W plugged into a 5v 2amp usb port, to get the 10W of heat dissipation the resistor must be 2.5 ohms and all is ok.
But if I connect the same resistor to a usb port that "supplies 5v and 1amp" the circuit current should be 2 amps anyway because V = IR and with that the resistor will dissipate 10W because P = V ^ 2 / R, right?
What am I missing? I suppose that in a heater there must be other components that provokes this?, I read that when the devices demand more current that source provies, the voltage source drops to maintain the required current.
But I don't see how my heater "demands" a certain amount of current if it should be defined by I = V / R
(I only know some basic of electricity and all this arose because I want to buy some heatpads that work at 5v and 2A and I was wondering if connecting it to the usb3.0 of my laptop would give me satisfactory results and because im curious xd)


texts: What value resistors should I use for this LED?

texts:
I'm trying to figure out the actual value resistance I need for the RGB LED I bought from here: http://www.adafruit.com/products/314#Description

According to most of the online calculators, for the Red LED I need 120R, Green needs 24R, and Blue needs 24R.

Can anyone confirm that these are suitable values to get both bright and even illumination? Also, I calculated these values taking the maximum voltage drop into account, so 2.5 for Red and 4.5 for Green and Blue. Is this the best way of calculating the values?


texts: Identify unknown transistor (possibly faulty LM35 temperature sensor)

texts:
I have a transistor I know practically nothing about. It was included with an Arduino I got off the internet.

It has the words 36RA, LM35, and DZ on the flat side of the plastic. I have a digital multimeter with a function for measuring hFE, but I don't have access to the data sheet that would supposedly tell me what reading I should get because I don't know the model code or manufacturer. The symbol/function for testing diodes is on the 2K\$\Omega\$ function.

I have this data from experimenting:
(With flat side of plastic facing me)
Resistance between central pin (black probe) and left pin (red): 1.307k\$\Omega\$
Resistance between central pin (black) and right (red): 0.873k\$\Omega\$
hFE value for NPN with transistor on CBE: 25
hFE value for NPN on EBC (backwards): 295
hFE for PNP on CBE: 289
hFE for PNP on EBC : 24-25
hFE for PNP on ECB: fluctuates between 0 and 22
hFE for PNP on BCE: 135

In all measurements not stated the value was infinity or there was no response.

I'm a beginner at electronics (in case it wasn't evident).


texts:
In RF PCB design ~1GHz, when should I worry about orientation of inductors in relation to the magnetic fields, I have seen application notes from manufactures where they pointed out, that it was very important to orient inductors correctly, or else the induced magnetic field would effect the design performance.

In a differential signal path, it is understandable that two inductors placed in close range, could affect each other and degrade performance.

But when does this apply, should I always place inductors right angles, or how do I determine when it is necessary ?

Snapshot from TRC105 reference design, just as an example.


texts: How to calculate current limiter resistors for ULN2803 and Relay?

texts:
I'm designing a digital I/O, and for the outputs I have ULN2803 and relays. I have the schematic below.

The coil current of relay is 16.7mA, ULN2803's max input current is 1.35mA and output current is 500mA/per channel used.

How should I calculate the current limiter resistors? My MCU works with 3.3V, driving the relays with 24V. What happens if a current flows more than 16.7mA to the relays?

And should I use pull-up or down resistors for input and outputs. I don't want any floating pin and activate the relay when I don't want.

THANK YOU!


texts: Printed circuit board connector identification

texts:
I have a PCB with some connectors and wanted to identify which type there are of.
How do the experts approach the problem, to identify the type?
For example, the picture below shows a connector, obviously written CAN on it.
So it seems easy to say, it must be a CAN Bus. The L and H could be CAN-High and CAN-Low, - maybe for Ground and + for Vcc. So it already turns into guessing.

If you look into the CAN Bus specification, maybe on automotive part, there are always much more wires than just these 4. So is it really a CAN Bus?
Another one:
If you look closely, there is BUS written on it, so good indication for a BUS connector.
When searching around the internet, BUSes which wires are sometimes labelled A or B, may lead to the idea, it maybe a RS485 Bus connector. But this is again a wild guess.
Also it seems that many companies, label + and - or A and B differently, from what i read so far.
If this is really a RS485, why it has 4 wires, the only types I could find are 2 wired or 4 wired, but the 4 wired has actually 5 wires in the schematic description TD+,TD-,RD+,RD-,GND. Again confusing.

So is there an expert approach or best practice for identifying connectors or electric components in general or is this only possible by experience?


texts:
[This is my MatLab code and I am trying to take a plot of what I have done, but when I run the code the plots are all empty
Do you know how I can fix it?

clear
clc
steptime= 0.0001;
t=[10;10;10];

% position parameters
% p=[x_initial y_initial z_initial]
p_0= [0.999;0.999;0.999];
p_env=[1;1;1];
p_desire=[1.1;1.1;1.1];

% Parameters
m = 0.5;
K_E=1000;
K_V=5;
K_P=3;

k_e=K_E*eye(3);
k_v=K_V*eye(3);
k_p=K_P*eye(3);

f_e = (k_e*p_0) - (k_e*p_env);
sim('Force_Control_Finger')

subplot(2,1,1)
plot(t,p_0)
xlabel('time[s]')
ylabel('position')

subplot(2,1,2)
plot(t,f_e)
xlabel('time[s]')
ylabel('f_e[N]')

figure
plot(t,f_e)
xlabel('time[s]')
ylabel('f_e[N]')


texts:
Short story: I want to solder cable to a pretty delicate looking board. There is not a lot of room to get at things so I need to be careful not to just screw everything up plus the PCB looks fragile (that could just be my lack of understanding). What should I do to avoid killing it while successfully attaching the new wires?

Longer story: I have two eGo-T vape batteries which have been physically busted for various reasons. The parts of the official one all work (I know this because I was careless taking it apart and burned my fingers). I want to build a mod or two with them. The last time I used a soldering iron was over half my life ago and so I figure I have probably forgotten anything useful. The board on the 510 thread head has the little board and button all in place but the wires are way too thin for the current that they were coping with (factory/design fault) so I want to put a thicker more durable cable on before I set the head into a box of some kind and rig up a battery (perhaps with some form of variable voltage regulator). Basically with the first build I am just wanting to make a new case and replace the wiring with something that is up to the job. What I am worried about is cooking the little board and making it useless.


texts: How can I improve this digital-output / digital input (automotive)

texts:
I'm creating some circuits required in a student-built electric-vehicle application. There are no heavy loads on the low-voltage +12V system.
What I have below is a circuit that does some threshold detection (LEFT), which indicates that status to an isolated output-circuit (RIGHT).

The intention here is that U3 (LM555) and Q2 (IRF9540N) should act in a complementary way to each other:

SIG=LOW => Q2 ON

SIG=HIGH => U3 ACTIVE

I've tested this output circuit using a relay to switch SIG to ground, and that works well!
In attempting to iterate a solid-state-only design, I attempted to replace the relay with darlington optocoupler U2 which produces the following effects:

When SIG is pulled HIGH (R5), U3 is active and Q2 is OFF - as expected.

When comparator U1 triggers, driving optocoupler U2 @ ~4mA, SIG is not pulled entirely to ground - rather, about 0.5V as measured with a multimeter. This appears to be enough to (partially) activate both U3 and Q2. Q2 is clearly on because Vgs is much less than Vgs(th). What's curious is that U3 appears to drive LOAD-B on.
Does this imply that there is some oscillation in SIG or at least at the ENABLE pin of U3? I would have expected the chip to be either active (oscillating) or not. Not some intermediate state.

I have a few ideas on how to improve this circuit, but was wondering what readers here might think.
Specifically, my questions are:

Is this a naive approach to creating a voltage-robust input in the right-hand circuit? I want to protect somewhat against noise and wiring mishaps.
Is the 0.5V an artefact of some minimum Vce that is possible across the optocoupler? Remember, substituting a relay or switch works perfectly. I'm a lot more comfortable working with MOSFETs than BJTs (and therefore optos) - this is honestly my first time trying to use one.
Is a viable solution to schmitt-trigger on the right-hand side's input to create a purely digital signal, and therefore create a strictly complementary operation of Q2 and U3?

Note: supporting components for U3 555 timer now shown to avoid ambiguity.


texts: I am using an Arduino as ISP to program an Attiny85. Is there any way to disable the reset pin such that it is not functional. I think this is a fuse setting but I am not sure.


texts:
I am using 6N137 opto-isolator for my circuit.

I have attached schematic for the same. I am giving Input and Enable from SMPS as shown and ground is same.  VCC and EN is 3.3V from SMPS.

But while checking output voltage when Input and EN is High ( VCC is also High ie 3.3V ), I am getting Logic High at output (3.3V).

Ground for both is same.

Link for datasheet : http://www.vishay.com/docs/84732/6n137.pdf

Can anyone help me for above issue.

Thanks in advance.


texts:
I have a few panel lights which come with normal non-dimmable constant current drivers.

I want to add a dimming feature to them, please suggest me a circuit that I can use with Arduino/ESP8266 to control the brightness of the leds.

I tried using circuits provided for controlling 12V led strips with an Arduino but they didn't work. My led blinks when at lower brightness levels and gets stable only when it reaches almost the full brightness.

My problem is similar to the one mentioned here: how to control constant current led driver output with pwm?

OEM LED Driver ratings: 32Vdc, 130mA, CC.

The IC used in my led driver is BP2327. Here is the datasheet for it.


texts: Making a suitable antenna for a crystal radio

texts:
I'm trying to build a simple AM crystal radio, however, I'm not getting any voltage registered when using it. This is the kind that's only powered by the radio waves. The site I was using to design it makes the circuit clear and how the radio works pretty self-explanatory, but I couldn't read their diagram for making a good antenna. Right now I just have a wad of 22 gauge insulated speaker wire I'm holding up really high so I figured I'd ask stackexchange how to make a good antenna.

How can I build a good antenna for a crystal radio? Here's the site http://www.sciencebuddies.org/science-fair-projects/project_ideas/Elec_p014.shtml


texts:
This is a flex cable from a kindle that connects the motherboard to the lcd.
The pins at the edge are broken and not making any contact with the connector.

Is there any salvation for this?
If there's no solution will a universal flex cable work as long it has the same amount of pins and pitch?


texts: How many flash drives can you power with an iPhone battery?

texts:
I will give a very specific example:
Hardware:

Iphone X device with 2716 mAH capacity battery, 3.81V
Iphone "dongle" lightning to USB 3.0 port, bus-powered
USB hub 3.0, bus-powered, 3V, 200 mA, four-ports
USB flash drives 3.0, 900 mA and 5V +- 10% operating voltage bus-powered

Circuit setting and analysis:

Connect Iphone to dongle, to USB hub and plug in USB flash drives.For me, the circuit is in series for component 3 (Hub) and components 4 (the drives). The drives are in parallel inside their component.

Hence the hub receives 3.81/2 = 1.905 V and the drives 1.905 V.
The flash drives receive x/n mA where n is the number of drives plugged in and x the current in amps release by the IPhone battery.
Here I have a missing variable: maximum discharge current of the iPhone X battery, which may of may not be limited by software.

I have battery capacity at 2716mAH, and current requirements of 4*900mA  = 3,600 mA so I can last up to 2716seconds on a full iPhone battery theoretically (if the battery had a 5V voltage).

Questions

Is the above analysis correct?
When an electrical device says 5V operating voltage, 900mA, does it have to be these precise conditions or can power the device with equivalent wattage i.e 1.905V and 2,362 mA?
Assuming maximum discharge current is 3,600 mA, how many USB flash drives as above can I bus power?

Edits

For 1.,it was commented that the circuit is in parallel, the USB hub is not in series.
For 2., a link was provided by brhans Choosing power supply, how to get the voltage and current ratings?  to a similar question which advises to keep voltage within recommended tolerance band and current amperage too. Hence, as user towe commented, there will be a problem connecting 5V appliances to 3.8 V battery. Maybe some USB hubs can do this (ex:)
User Chris Patton has mentioned that connecting multiple flash drives to a phone is a bad idea. Why is that?


texts: Why does the current not skip resistors R3 and R5 when R6 and R4 have no resistance?

texts: I do not understand why the current still flows through resistors R3 and R5 when R6 and R4's resistance is 0.  To me, it would seem that the current would skip R3 and R5, however the answer key says otherwise. I have attached the problem and answer key.  I realize that this is not the question being asked in the problem, however when I solved it I just took out the R3 and R5 so I got a different answer for the current flowing through the voltage source.


texts:
I am pretty new to electronic design so sorry in advance if the question is too naive.

I need to build a small portable 1Hz pulse generator and connect it to a FPGA input pin, configured in LVCMOS 1.8V. This is supposed to emulate a GPS PPS signal for testing purpose, without requiring a GPS signal/antenna.

Currently my plan is to use a 9V battery and use a 555 timer to build the pulses.
This part is OK, and I have successfully simulated it with LTSpice to verify my resistances and capacitors values meet the desired frequency and duty cycle.

The step where I'm stuck is how to interface it cleanly to the FPGA, and be 100% sure I won't damage it.
I have tried with an LDO (LT3021-1.8) after the 555, but the simulation tells that the rising edge goes up to 3V for a small amount of time before stabilizing at 1.8V.
Remembering my electronics lessons, I tried a divider (with two resistances) and a LM358 configured in follower.
The results are a little better but the simulation still shows a rise to 2.4V during the rising edge.

I discovered there are specific component called "voltage shifter" that could  be appropriate for what I'm looking after, but I'm having a hard time finding one with LVCMOS 1.8V output, and that I can solder by myself.
Do you have any suggestion for a component that would fit the purpose ?
Would a Zener diode help to limit the output to 1.8 V ?

Also, for running the simulation I need to simulate the load of the FPGA input pin, but cannot find such information in the datasheet (this is a  Xilink Z7000). What would be a correct way to simulate this load (what impedance) ?


texts:
I am using a PIC 12F508 for a project and just want to make sure I understand the specifications in the datasheet for a logic low and a logic high.

Here's the datasheet for reference.  The specs I'm using are on page 73.

The pin in question is the MCLR pin which I have set in the configuration bits as an input so it's not functioning as a reset for the micro controller.

For a logic low it says 0.15 VDD I take it that means it's a percentage of the micro controllers supply voltage (VDD) right?

So say my VDD is 3.50V so 3.50 * 0.15 = 525 millivolts. So as long as the input remains below 525 millivolts the PIC will read it as a logic low?

I take it the same would apply to a logic high 3.50 * 0.85 = 2.975V or above would be read as a logic high right?


texts: Is the rise time of the output of a logic IC or optocoupler independent of the rise time of the input?

texts:
Is the rise time of the output of a logic IC (e.g. flip-flop or inverter) or optocoupler independent or dependent on the rise time of the input?  If the answer is dependent, are there any other devices where the rise time of the output is independent of the rise time of the input?

For example, I have a 555 timer output running in astable mode with a 50% duty cycle producing a 1.5kHz square wave where my scope says the rise time is approximately 400ns (and this changes if I change the frequency of the 555 output).  I'd like to hook something up to the output of the 555, like a flip-flop or inverter or optocoupler (or anything that does the trick) to get a square wave with a rise time that's:
1) less than 400ns and 2) preferably, independent of the 555 frequency (i.e., same whether I configure the 555 to output at 1.5kHz or 10kHz).


texts:
I have several Christmas lights with different AC adapters.
First case
In the label of one of them, I read:
Primary: 220-240 V ~ 50/60 Hz
Secondary: 31 V DC 3.6 W

In the label of the cable connecting this AC adapter to the LED array:
Lamp: 3.2 V
0.064 W
80 LED

I can not understand if this is referred to the single LEDs, but the total amount of LED seems to be 80.
How are they connected, then?
In the case of a series connection, each of them would have a 0.3875 V voltage drop, which maybe is too small for a LED. If they were parallel, 31 V seems too much for each of them, and the total available current 3.6 W / 31 V = 0.1161 would be 0.00145 per LED. So, neither of these solutions seems correct.
Second case
In another LED string, I have a 4.5 V battery power supply, with no labels and therefore no indication about the current and the number of LEDs. Do they have a parallel connection?


texts: Basys 3 FPGA sequential circuit reset remotely?

texts:
Since the COVID-19 pandemic, I'm teaching Verilog lab online. I let each student remotely connect to a computer having Xilinx Vivado installed, a Basys 3 board connected and powered on, and a camera that see the board so they can see the results on LEDs and the seven-segment display.

I'm preparing a lab about Counters, but I've an issue with how to remotely handle the reset signal. Do you have any thoughts that can help here, instead of relying on a physical toggle button due to remote access?


texts: Do any microcontrollers allow steering of inputs to outputs?

texts:
Are there any MCUs which allow input signals to be connected (by software) to outputs?

The main requirement is that should not involve sampling (either by MCU code or SCTimers) as this limits the speed of the steered signal to that of the MCU.

The signals I'm looking at steering are 480Mbit USB2, which is faster than common MCUs.

I suppose I'm looking for a sort of MCU with built in buffers, as such a circuit could be made from a common MCU and a couple of buffers.


texts: How to power a OLED 128x128 display from 3.3v microcontroller board?

texts:
I recently purchased a small 1 inch OLED screen. In the datasheet, it shows the max power requirements as:

Operation: 3.5v
Logic: 2.6v
IO: 3.5v
Display: 13.5v

I figure I can directly connect the operation and IO pins to the 3.3v power. I guess for the logic pin, I'd use a voltage divider circuit?
What about the display? Since it's a small little screen, I don't expect the current to be much of an issue, but how do I boost the voltage from 3.3v to 13v?

Since I'm new, I would normally use a pre-made breakout board, but in this case I'd rather learn how to do it instead.

Edit: The driver is a SSD1351. Here is a link to the datasheet: SSD1351

Edit 2: The datasheet I have for the display is marked as 'Confidential' and doesn't appear available online. I got it sent in email from the manufacturer. So I don't have a link, but I found the current information for the display:

30% of display: 13.3 typical, 17.0 max mA
60% of display: 23.2 typical, 29.0 max mA
100% of display: 33.4 typical, 42.0 max mA


texts: Circuit that takes input signal and controls led

texts: I am trying to design a circuit that compares a recorded signal to a stock signal. If they are not similar it then inputs a signal into a circuit which will change the pulse of the led to stimulate a channel until these signals are relatively similar. (Feedback loop) It will take a input that (changes the frequency) in which the led pulses. Any help is great.


texts: How do I calculate the temperature rise in the ferrite core?

texts:
This question might seem basic but I would like to state it.
I would like to calculate the operating/Rise temperature of the ferrite core of an inductor.
I am modelling my own bobbins for the core so I need to decide on the material/filament to use for 3D printing which can take the temperature of the core without causing any damage or melting of the bobbins. I looked into it but could not get the answer I am looking for.
Inductor specifications which might be useful for better understanding:

E70 core
N87 material
v= 450VRMS
I=40A
f=85kHz
Litz wire for the windings
distributed air gap on each leg

Please help me with this, any links or any articles would be great too.


texts: Will Increased amount of Amps affect dc motors

texts: I've a 12 volt 1 Amp rated adapter and would like to hook up 2 12 volt 0.18 Amps Dc motor in parallel circuit to power them up, would the over rated amps effect my dc motors and if so how can i reduce Amps without reducing its volts ?


texts: Ferrite beads in Quasi-Resonant Switch-Mode Power Supply (QRSMPS) primary?

texts:
I am using the Fairchild FSCQ series and I am shocked that nowhere is there any guide for sizing the bead on the drain. The frequency range is 24kHz min. to (looks like) 90kHz.

There is also another one on one of the outputs, but that seems to be straightforward, except, according to them, the corner frequency cannot be too low or it may affect stability. I assume that means it must be above the 24kHz.

At any rate, my intuition tells me that board layout will affect the sizing of Bead 101 in the diagram, and since they have no way of telling how the board will be designed, have left out the value.

Bead L202 on a 140v., 6A load, was sized at 5uH, 3A. Noteworthy is that is referred to as a L202, and not just "Bead" as in 101.

Anyway, the question is, does anyone have any ideas as to how to size Bead 101?

Data Sheet


texts: Arduino for measuring Farads (vs micro/pico farads)

texts:
I've been looking for a way to use an arduino to measure capacitance of a supercapacitor that is likely to have a 4F capacitance based on experiments of others.
Several people have experimented with arduino to measure capacitance in the neighborhood of picofarads and microfarads, experimentally demonstrating accuracy of different approaches. Example1.
"One meter would accurately measure values in the 1000 μF range, but it would fail in the nF and pF range. Another capacitance meter was accurate in the nF and pF ranges, but failed in the μF range."
Working through a supercapacitor experiment with Robert Murray-Smith, I see that the supercapacitor can hold 4 farads.
Has anyone experimented with accurately measuring larger capacitance with an Arduino and, if so, is there a documented approach that I can use as a starting point?
Any pointers are definitely appreciated.


texts:
I am working on following circuit involving BC107 NPN Philips TO-92 transistor and voltage source of 4.2 V.

simulate this circuit – Schematic created using CircuitLab

I got some confusion when measuring collector's current. I was expecting that to be at least 0.2 A but when I insert probes and measure current as shown in the picture I get a reading of 0.0079 A. That would mean an DC Gain (beta/hFE) of Ic/Ib=0.0079/0.0023=~3.37, while this transistor should yield a gain of about 40-200 (I do not have spec for TO-92 though, it's taken from datasheet for BC107 TO-18, can't find any spec for TO-92...).

I would like to understand why am I getting 0.0079 reading when the base current (Ib) is 0.00234 A (confirmed with multimeter).

Ib = (4.2 - 0.7) / 1480 = 0.0023

Ic (expected) = Ib * hFE = 0.0023 * [40:200] = [0.092:0.460] [A]

but real Ic = 0.0079 [A]


texts: What is wrong with this broken analog oscilloscope?

texts:
I own an Hameg 204 analog oscilloscope.

Unfortunately the x-axis oscillation on the CRT screen is broken. I am looking for advice on how to fix this.

My background: I have fixed several little electronics devices. Examples include networks switch with burnt capacitors. This oscilloscope is much more complicated and a little above my level to handle it myself.

Precise description of the issue

Expected behavior: the CRT ray moves from the far left to the far right of the CRT screen.
Actual behavior: the CRT ray is stuck at 60% of the x-axis of the screen (y-axis works fine). The x-pos button does nothing from 100 down to 50% and move the line start further right when turned from 50% to 0%.

When I activate the "x magn x10" button, the ray moves from 60% to the far right.

Basically, with the "x magn x10" trick, I have a working oscilloscope with only 40% of the original screen width. These "40%" do not depend on the time resolution.

What I already did

The following was made with "x magn x10" always activated.

First thing I did what to get the schematics: http://www.sky-messtechnik.de/images/PDFs/HM204-1.pdf .

I made the hypothesis the issue comes from a faulty component in the 'x-final amplifier' (page 37 reproduced below).

I then used a working (digital) oscilloscope to check "from S281" point (it is not only 'from CT' as stated in the manual but also 'from timebase').
Here I see the x-oscillation I expected to see, with 0V in the middle (see image below). I can also confirm that x-pos (bottom left) works as intended (-12V to 0V).

"Inside" the x-final amplifier though, the situation is very different. I always see the same pattern (at both 'W2-6 CRT', Chp12, ...) but obviously with different voltages. depending on the location in the amplifier (see image below; minimum value is very close to 0V).

I do not see any weird-looking component (see picture).

EDIT: I also checked all power rails and all are at their expected voltage.

Where you can help

As the board is quite difficult to take apart (so I would like to do it only once), I am looking for some advice on how to precisely locate the faulty component so I can order a replacement.

I am hoping that for an experienced eye, the pattern would be typical of a specific component failure.

If needed, I can make further measurements.

EDIT: new measurement:

T2101, base (to R2101):

T2101, collector (to R2110):

T2101, emitter (to R2100/R2101/R2108):

T2102, base (to R2103):

T2102, collector (to R2112):

T2102, emitter (to R2109, VR2100, VR2101):


texts: Why do most guitar amps have a preamp and a power amp section?

texts:
I have read that the preamp boosts the signal so that it is strong enough to send to the power amp section, but it seems like there must be more to it than that.
Two thoughts I have had:

The preamp generally has the EQ controls on it, maybe applying EQ to the stronger signal from the power amp would require very expensive components.
Maybe there is a need to first amplify the voltage of the signal and then amplify the current of the signal, so you need separate systems to do each of those things.

Why is it difficult to build a guitar amp with a single amplifier section that goes from the very weak signal from the guitar, to the very strong signal that drives the speaker?


texts: Arduino/Netduino: connecting a second power supply's ground to GND pin

texts:
I'm planning to play around with an addressable LED strip and a Netduino, and having read some tutorials I've learned that I will need an external power supply to provide enough current to the LEDs. According to the tutorials an old PC power supply suffices since one of the 4 pins on the molex connectors provides the 5V required, and the power supply will be able to provide more than enough current. All well and good.

Now, a couple of tutorials (this one and this one, for instance) mention that I should connect the strip's 5V input and GND pins to the 5V and GND pins on one of the power supply's molex connectors, which makes sense. However, the tutorials also mention that I should connect this ground pin to one of the Netduino's GND pins as well, which is the part that worries me.

If I power the Netduino via USB (during development, for instance), wouldn't that mean we have two different grounds (namely, the PC's ground and the external power supply's ground) in the same circuit? I'm no expert when it comes to electronics but it seems to me like this might be a recipe for disaster.

I'm probably missing something though, so I thought I'd check it here. What would happen if I connected the netduino to my laptop via USB but also connected an external power supply's ground to the netduino GND pin? Would it make a difference if I powered the laptop via battery as opposed to plugged into a wall outlet?


texts:
I got a new diff probe, I am trying it out on RS485. I'm triggering on the rising edge. The RS485 is running at 25Mhz.

Does the eye diagram look good?

Could I double the speed (50MHz) and be ok? (do I need to worry about overshoot?)

What should one look for in an eye diagram?

Probe is TEK TDP1000 (1GHz, 200MHz scope) cable length is 1m with 50MHz transcievers.


texts: Timestep too small,.... and DELMIN increased

texts: The circuit simply checks for same signals across the XOR gate. When the top button is pressed, fatal error as stated pops up.


texts: MOSFET Circuits: Which value of \$ V_S \$ should I choose?

texts:
1)\$ V_S   \$ potentially has two values. Which value of \$ V_S   \$ should I choose?

2) Why?

3) What should I generalize from here about value of \$ V_S  \$  that should be chosen while solving such problems?


texts: Are old frequency counters good deals or a waste of money?

texts:
Other than knowing that you get the best results from a frequency counter by using a high quality crystal, like an oven crystal, I don't know too much about a frequency counters.

I notice that you can get old big name frequency counters, like HP 53XX series, for about $300 used.

On the other hand you can new cheap frequency counters like the Victor for as little as $100. Another cheap brand is the Instek GFC-8270H/8131H which new is about $350.

Have these new frequency counters made the older ones completely obsolete, or are the older ones good deals with features and quality the new ones don't have in the $300 price range?

Note that the new counters tend to be MUCH smaller than the old counters, so if they are "the same" I would prefer a smaller counter on size issues alone. However, if the older counter is a lot more accurate/stable, then I might be willing to put up with the large size.

Also, I notice that "high precision clock" fanatics, like those guys that count leap seconds and stuff like that seem to prefer the old counters, so that might say something.


texts: How to get uni polar sinusoidal wave from buck converter?

texts:
I am trying to build a pure sine wave inverter by using a buck converter cascaded with a square inverter. My hope is that I can vary the duty cycle in such a fashion so as to reach a fully rectified sinusoidal output with desired frequency so he square inverter will give me pure sinusoidal output which can be stepped up using a transformer to run a 25W load.

My question is about the design of Buck converter because I am not sure about how to calculate the values of 'L' and 'C'?
I know the constant duty cycle formulas but if there is another helpful resource here, then I would love to know about it.

Thanks for your help!


texts:
Is it possible to set a delay between two components on Ltspice ? Actually I just want to simulate the time for a sensor it takes to react (set an output) to an exciting signal.
This is for taking into account the impact of a delay with respect to the stability of the system into an AC simulation.
Have a nice day !


texts:
I would like to create an area on my PCB where you can write on with a pen.
Is this possible, and if so how should I do it?


texts: How to charge LiPo battery using a wind generator?

texts:
For a home robotics project I want to fly a kite using a computer. For this to happen I need an electro motor up in the air (attached to the kite) which obviously needs a battery up there as well. From some smart people I understand that using a LiPo battery would be the best for this (because of the high energy to weight ratio). I also understand however, that a LiPo battery needs a special charger. My end goal is to charge this battery in the air by also hanging a small wind-generator under the kite so that the kite can fly indefinitely. If the battery cannot be charged while it is being used I can of course use two batteries, charging one while the other one is used.

So let's say I've got a 11.1V LiPo battery which uses about 500mA to 1A for the motor.

My question: is it possible to charge this battery from a wind generator, and if so, what hardware (preferably very low-budget) would I need for this to happen?

All tips are welcome!

[EDIT]
Wow! I am overwelmed by the amount of in depth answers. I am a bit lost in them as well though, and I think I am after a bit more of a "beginners answer". As far as I understand, a wind generator supplies AC power in varying amount of Volts and Amps (right?), which needs to be converted to DC power with a constant amount of Amps (right?). So I guess that would mean I need the following order: Wind generator => Rectifier => Li-Polymer Battery Charge Management Controller (like e.g. this one) => LiPo battery pack.

Is this correct?


texts: I have a doubt on taking pad dimensions in this below picture what is the pad width and height.any body kindly clear my doubt

texts: See this picture and kindly clear my doubt thanks for your help


texts: Howcome there is current flowing through the gate of this transistor?

texts:
I have a few conceptual questions:

If there wasn't Rg (Resistor between gate and drain), would Vin = Vout then?
For small signal analysis, current can flow through the gate (AC) if there's a voltage source connected to it, right?


texts:
I'm currently facing a big problem.
I've an MCU (STM32L4) connected to an SD card (SDIO) which stores tons of data (5Gb) from a microphone. I need to send this data as fast as possible from SD card to my PC.
With a serial port this is to slow, since the max baud rate of my MCU is 115kb/s.
How can I solve this? I'm thinking about using an FTDI module but for what I'm reading the speed is always limited by MCU baud rate.
Best Regards


texts: Does a voice coil vibrate at the same frequency as the source sound file?

texts: As a disclaimer I know very little about this so I'm probably describing this in a very imprecise way. Say you generated a sine wave on your computer at 800Hz and played it through a speaker. Would the speaker also vibrate at 800Hz?


texts: Can low brigtness extend life of CCFL lamp in laptop LCD backlight?

texts:
I have really good and old laptop (IBM t60p with t61p board). I just replaced whole screen because CCFL lamp died after many years.

Can I extend life of CCFL by using laptop with reduced brightness when I don't need 100%?

It is hard to find new LCD or CCFL for this model, I want it to last another few years.


texts:
I am trying to understand the concept of noise figure and the best achievable SNR.

The noise figure is a measure how much a device degrades the SNR. Say I have a receiver with a NF of 16dB, then the output SNR is smaller by 16dB than the input SNR. But what is the input SNR? Of course, it depends on some parameters.

As an example, let's say the system has a bandwidth of 100 MHz. Furthermore the antenna is ideal with an output impedance of 50 Ohm, so my receiver should have an input resistance of 50 Ohm.

Now suppose I have a hypothetical receiver which requires (due to hypothetical constraints, e.g. linearity) an input amplitude of 50mV but has NF=0dB (noise less). Then the output SNR represents the best achievable SNR in this setting and should be given by:

$$
\rm SNR = 10 \log \left( \frac{\frac{\hat{v}^2}{2R}}{k T B} \right) = 10 \log \left( \frac{50\cdot10^{-3}}{2 k T 50 \cdot 100 \cdot 10^{6}} \right) = 77.98 \mathrm{dB}
$$

This sounds a little bit low too me given the fact 50mV is not too small.

The SNR could be improved by making the antenna resistance smaller (but to my understanding this should be 50 Ohm to match it with the impedance of the air).

Is the best achievable SNR with an ideal receiver in a typical setting like this really so low or are there some flaws in my understanding?


texts: Its a good practice use dc-dc converters and linear regulators in the same design?

texts:
Its a good practice use dc-dc converters and linear regulators? Or its better don't mix them?

Better use all linear tecnology or dc-dc converters in "cascade" or dc-dc with multiple outputs?


texts: AC Current Sensor to detect treadmill usage

texts:
I would like to build an AC current sensor to detect if my treadmill is being used (the treadmill would plug into my device, which is plugged into the wall). I would then like my device to tell me what the AC current is (so I can see if the treadmill is on) and transmit this info via Wifi.

What kind of components would I need, and at what cost? I am open to using the Arduino, but if it can be built without one that's preferable.


texts: How do I reduce the time delay in the HC-SR501 motion sensor?

texts:
I have integrated this sensor to trigger a water pump to dispense water/ sanitiser.
However, this sensor stays on for 5 seconds minimum after the person moves out range.
I have tweaked the time delay potentiometer to the lowest and that's 5 seconds.
I want to be able to reduce to just 1 second or TURN OFF as soon as the object/person moves out of range of the motion sensor, so as not to waste water.
How do I do that?
I understand that the sensor has a limitation. How can I circumvent it,
or devise something around it to shut off before the default 5 second minimum delay?
HCSR501 datasheet.
This device has a BISS0001 passive IR switch that detects motion.
Look at the delay time 'minimum stating 5 secs adjustable (snapshot from the data sheet.) This is the one I want to reduce even further.

Circuit diagram from the data sheet.

Found an interesting link on Youtube that tells to short the R13 and R33 so that the delay time gets reduced.
I shorted the resistors - still no effect.
Video link is :
https://www.youtube.com/watch?v=juOtoUabyH8


texts: How, exactly, does the 'input signal' wave(s) modify the carrier-wave of a radio signal?

texts:
I cannot find a simple (or really, not-so-simple) explanation of how mixing the high-frequency carrier wave with the lower-frequency input signal works...
Is it entirely due to constructive and destructive interference?
Also, are the carrier-wave and modifying wave created and broadcast on all the same equipment?  Broadcast using the same antennae, etc.?


texts:
Recently my electric clothing dryer stopped working. Blew the thermal fuse. replaced. Later the heat still wasn't working and I found a lack of continuity on a couple of terminals on the timer, the heating element circuit could not be closed. There is just too much corrosion even after cleaning to get a good connection inside the timer.

Thing is this is a very basic mechanical timer/switch that costs 75$. I feel like for the same price I could run this with an ardunio instead. More fun and way cooler.

So now on to my problem. I cant seem to find a relay suitable for the load generated by the dryer. I need a relay that can handle 240 volts and from what I can see would need to handle about 4k watts? Amazon, adafruit, nothing as far as I can find. I am wondering if someone with more electrical experience can suggest an appropriate relay to use.

PS Notes:
Looking a bit harder I found this under furnace parts on amazon. https://www.amazon.com/dp/B019132A1I?psc=1

Thanks all for your input. I suspected the reasoning behind a very simple (now I know what to call it) centrifugal switch. The heater cannot physically be a completed circuit without engaging the blower. I realize this now looking at the order of the copper bars. I don't know that is really intentional as a "safety" feature, but fair enough, you're right I don't know for sure.

I've decided to NOT do this project simply considering the risk/reward as someone pointed out. I strongly believe the risk truly isn't that great, and ill explain my reasoning below, but in any case, not a great first Arduino project. Maybe in the future if I have a spare dryer and more time to work out the safety aspects. I'm pretty sure we could, with time, make an even safer dryer that the manufacturer.

So here is why I think the danger of this is pretty exaggerated.

I still strongly believe that in the event the blower does not engage the thermostat and or thermal fuse would blow very quickly, stopping heat production.

Lets say for whatever reason the element does get stuck on. Not ideal right? but is it truly going to start a fire? I am certain lint in the exhaust is infinitely more dangerous, and ONLY when the blower is running.

The heating element itself is well sealed away from anything flammable, it is completely encased in a few layers of metal, the floor is cement and the basement wall is cement. Consider that only fresh air is pulled into the element. It is NOT full of flammable lint, the lint is no where near the element. Only when the blower is on can the heat reach anything in the exhaust section.

Having said that there are a few factors here. 1. my wife wants the dryer fixed sooner than later :O and 2. I can't deny that SOME risk at least potentially exists. 3. I'm a coder with limited electrical experience. My first project should likely not involve 240v or 4k watts :P Never the less that's to you guys I did learn a few things anyway.


texts:
I am designing a small audio amp and am experiencing some weird oscillations in the first OPamp (NE5532), wich is setup as a noninverting amp. The amp is supplied with +-20V and has 100nf bypass capacitors directly at the supply-pins.

simulate this circuit – Schematic created using CircuitLab

Only the inverting input pins are oscillating at 250kHz with an amplitude of 2V.

The supply is linear regulated (LM317,LM337) and has no measureable noise/ripple.

What could be the reason?

Thanks in advance

EDIT:
I noticed, that the oscillation is quite intermittent. Then the smallest amount of signal on any pin will retrigger it.


texts: In need of hardware to connect to a mysql server over gprs

texts:
Has anyone come across any hardware that we can put out on a remote site (in a field) that uses a sim card to create a gprs connection to a mysql database server.

I've looked at the arduino but that protection we'd need to put around it to "industrialise" it is very costly,


texts:
I am following this video from EEV blog where he talks about  calculating heatsinks and I noticed that he does not talk about multiple components sharing a single  heatsink. I have lurked around the web but I have not been able to figure out how it is done.
This is the thermal circuit for a single transistor in a single heatsink as shown in the video

How would the thermal circuit for two or  three transistors mounted in the same heatsink look like?


texts: How does a Silicon-Controlled Rectifier (SCRs) work?

texts:
I know that when in a SCR the anode is made more positive with respect to cathode the two outermost p-n junction get forward-biased but the middle one is still reverse-biased  so no current flows through it but when a small gate current is applied to it the middle junction also get forward-biased and allows a huge amount of current to flow through it but in my text book it is not described at the atomic level what happens it is only it's working stated. Can anyone give an explanation of what is going on the atomic level.

Thanks

Akash


texts:
Is this an acceptable way to drive a mosfet? In this case, I'm trying to turn on a high current load, but in case the load is changing it's resistance/impedance, or in the possibility it's disconnected altogether, I still want the mosfet to turn fully on and not have Vgs be dependent on the load having a proper ground connection.
In this circuit, I'm using a 1K Ohm resistor in parallel with my load to ensure the mosfet when receiving gate drive voltage is always turned on, and outputting a voltage.
For context, this is going to be part of an automotive circuit where it's not uncommon that during production, damage can occur resulting in a disconnected load or short to ground. My end goal is to make this MOSFET perform nearly exactly like a relay. Link to the circuit below.
Apologies if this answer is facepalm levels of easy. I've never seen this method done anywhere else on the sitefor using High-Side N-Channel controlling, I'm not even really sure what I would search to find a circuit like this. MOSFET N-Channel High-Side Bypass Resistor?
Circuit


texts:
Is it possible to configure the Arduino to give me 0-10V analog input?

I realize that I can use a voltage divider. I was just wondering if I can use a larger range for the analog input.


texts: How do you burn the Arduino Boot Loader onto the Arduino BT?


texts: What's the purpose of a diode to Vcc at an LM339 output?

texts: I'm unable to figure out the purpose of this diode (1N4148) from the output of the comparator (LM339N) to VCC. It's not clamping anything as there's nothing that can pull that rail beyond VCC.


texts: How to protect LEDs from high voltage during NPN transitor transitions?

texts:
I am using a 555 timer and an NPN transistor to drive an array of 12 LEDs from a 9v battery, and a potentiometer to control the duty cycle. I am concerned about the voltages the LEDs will be subjected to during the transistor's on/off transitions.

My simulated circuits:

Top Level

PWM Driver

LED Array

Simulated Output

I understand that when the transistor is off, having 9v on the anode side of the LEDs is fine because there's no path to ground. Likewise, when the transistor is fully on, an operating voltage of just over 3 volts for my LEDs is fine. But real transistors won't transition between on and off instantaneously, so how can I protect my LEDs from voltage spikes that will either destroy them or wear them out faster? Is it even necessary for this circuit?


texts: How to determine the right microcontroller for your project?

texts:
I'm curious as to how would someone pick out their microcontroller for their project when it comes down to the horse power?

I am not talking about the hardware (ADC,DAC,SPI,ETC) as its more intuitive. I once posted here asking how to implement a digital filter into an Atmel Atmega328p, but they simply said, it wasn't 'up to speed'.

So what is up to speed? And how can I find out if its up to speed?

For example:

I have an Atmel Atmega328p @ 16MHz and I have it sampling an input sine wave 60Hz using the ADC.

The ADC is setup using an interrupt as well as using the running mode configuration sampling at 76KHz.

At each interrupt trigger I want it to run a task of running a difference equation of

$$Y_i = 0.1441U_i+0.2281U_{i-1}+0.1441U_{i-2}+0.6777Y_{i-1}-0.254Y_{i-2}$$

The way I understand it is that I have an interrupt that will be firing at every 13uS. I will need this task be in an another interrupt that fires right after every 13uS but needs to finish within the next ADC interrupt triggering.


texts: I have an SPST momentary tactile switch and want the pulse, whatever length, to be extended to 500ms (unless of course the button is pressed for longer than 500ms but we can ignore that if we hold the pulse form the rising edge). I don't know if there is a single IC to hold a pulse like this or if I can do it with passive components like resistors and capacitors.


texts: I2C write to Amis 30624 motor from Atsame54p20a in Atmel Studio

texts:
I have been trying to write to the amis 30624 stepper motor                      (http://www.onsemi.com/pub/Collateral/AMIS-30624-D.PDF) using I2C protocol but for some reason its giving me Receive not acknowledge error. I have followed all the steps of I2C protocol mentioned in the asf4 documentation(http://ww1.microchip.com/downloads/en/DeviceDoc/50002633A.pdf) but in vain. Can someone please help me? Here is my I2c Write function:

void I2C_Write(uint8_t address_reg)
{
    gpio_set_pin_pull_mode(SDA,GPIO_PULL_OFF);
    struct io_descriptor *Asynch_master_io;
    i2c_m_async_get_io_descriptor(&Asynch_master, &Asynch_master_io);
    i2c_m_async_enable(&Asynch_master);
    i2c_m_async_register_callback(&Asynch_master, I2C_M_ASYNC_TX_COMPLETE,
                                  (FUNC_PTR)Asynch_master_tx_complete);
    i2c_m_async_set_slaveaddr(&Asynch_master, 0x60,I2C_M_SEVEN);
    uint8_t var = address_reg;
    Asynch_master_example_str[0] = var;
    io_write(Asynch_master_io, Asynch_master_example_str,1);
    i2c_m_async_send_stop(&Asynch_master);
}

The SDA and SCL have been pulled up in the initialization. SERCOM3 is used. SDA is pulled down in I2C start.


texts:
I am starting to get beyond frustrated with gates and breadboards now in general because of this simple circuit (which is literally experiment #1 in my digital logic class).
Using only NAND gates, generate function F= (~A~C)+(~CD)+(ABC). Using only NOR gates, generate G= (~A+B)(A+~B)(~B+C). I can’t get a consistent Logic level for each binary code value; ie it works except it’s off for 1111, or it works except 0001-0011, etc. I will try to post as many pics of the info I’ve done so far. I cannot get this to work. F worked for a little but I messed around with it and lost it. The teacher is no help; says my designs are fine yet gives confusing vague answers about literal connection junctions and how and why each affects the other based on gate voltages or whatnot and states no resistors at all are needed and that it is irrelevant whether or not empty inputs remain floating or empty etc. based on everything I’ve read my thoughts have become soup. I know how to theoretically do it; I’ve even simulated it out and the functions worked fine. I cannot even count the hours I’ve wasted killing brain cells just literally making every possible combination on the literal breadboard to no avail. Tried different gate sets, even bought an arduino power supply. Sorry for such an idiotic question but I’m literally losing my interest in college based on this kindergarten level issue I can’t tackle. Thanks for any feedback/criticism/insults given, I truly appreciate it. Sorry for the vague schematics. Best regards.


texts: Very low leakage enhancement mode mosfets

texts:
I have a 1.8V logic signal that I would like to use to control an enhancement N-channel MOSFET to switch current through a resistor from the drain to a 3V power rail.
It's in a very power sensitive design. All of the enhancement-mode mosfets I looked at seem to specify max "Zero Gate Voltage Drain Current" Idss as 1 μA, which means if I would want the resistor/drain junction to go close to the 3V rail - say within 0.27V - the resistor would need to be a 270KΩ pull-up, and a 10μA on current, all of which are significant currents in a small battery powered application.
Update: I have limited board space, and need about 6 off devices. I have looked at some TI FemtoFET devices (bit of a pain to place as very small) and TPS22860 ultra low leakage load switches which might work.
Any suggestions - should I be using a different type of device?


texts: Can I power a DC fan from li ion to nimh?

texts:
I have a mini DC fan with a 2.5mm DC connector connected to a li ion battery provided by the manufacturer.
The li iom battery pack have 4 speeds switch from 3.5V(1.3W) to 7.4V(8W).

The question is can I use the 3xAA rechargeable nimh batteries, 1.2Vx3=3.6V to power the fan?
(And use more AAs to power up to 7.4V?)

Thank you


texts: Possible over-current issue in Arduino transistor circuit?

texts:
I have made the circuit illustrated below.  It uses a Sparkfun ProMicro to turn a pump on and off based on the signal from an Adafruit light sensor. I am using a signal from the ProMicro to the 2n2222 to switch 5v to the pump.  I have used this circuit in the past on other pumps with no problems.  I think this pump might draw too much current (about 550 mA at 5v) as the 2n2222 is getting very hot.  Circuit will run for a little while, then stop.  Will run again after it cools down.

Can I swap the 2n2222 for a higher current transistor like the ztx1053?  Do I need to upgrade the 1N4001 too?  Or am I on the wrong track, maybe there is another problem?


texts:
I posted a question earlier that helped me to understand Ohm's Law and how power is lost to length of wire due to resistance. So my original example was a 15A, 10ft cable surge protector plugged into a 15A 6 foot cable plugged into a extension cord 13A 10ft which then has the appliance's cable at 8 ft. The max power this device would need is 110 watts.

We worked out Ohms law:
=0.922×0.434Ω=0.367

I do not understand how the 0.367 W applies to the power needed (110 watts)? Does this mean if the TV needs to pull at max and requests 110 watts it will only receive 109.64? This is safe and will it not damage any of the TVs components, I heard under powering is very bad.


texts:
I've been trying to hook up an eMMC chip to a FPGA, that receives commands via a micro-controller to initialize and trigger write/read operations on given sectors.

I'm having trouble with the boot sequence of the MMC I'm using, I'm following the standards that you'll find here or here if you don't want to create an account on JEDEC. The document is rather dense and I'm a bit confused. This is what I do for now:

Startup: MMC is clocked, CMD line is pulled down
On user action, send CMD0 0x00 through CMD, it's a 48bits wide command built like this: cmd <= "01" & CMD0 & STUFF_BITS32 & "1001010" & '1'; (See p145/352 of the pdf file above). This is the GO_IDLE_STATE command. No response expected.
On user action, send CMD1 0x80FF8080. Built like the previous command, except CRC7 is 0010110. This is SEND_OP_COND command, which should send back data through the CMD line.
On user action, send CMD2 0x00. Built like the previous command, except CRC7 is 1100001. This is ALL_SEND_CID command, which should send back data through the CMD line.

Problem is, I don't get any data in. Any idea on what I'm doing wrong?

See below for captures from a logic analyzer;

Additional info: For now I've wired a Transcend MMCPlus 1GB card, following the pinouts I've found online. I have not connected the data lines yet.
I'm calculating the CRC7 with the info provided on p.254/352 (8.2.1).
The MMC Clock is divided from my 12MHz on-chip clock 32 times, making it ~375kHz for now (planning on speeding it up after initialization succeeds)


texts: Help identify a component on VS-TY2662-V1 LCD driver board

texts:
I just received what seems to be a faulty driver board for a 7inch LCD touchscreen. As soon as I opened the package, one of the components fell out of the static-protection bag. I'm now trying to determine what's going to cost me more: replacing this component on my own or sending the item back via international delivery.

This is the board:

There are three of these, looks like an ear drum inside heat shrink wire wrap. Perhaps an inductor? The one that was torn off (bottom one) has an inscription: 600 followed by what seems to be the letter V, but only the \ is visible. It has two leads that have been torn off. The board is produced by SainSmart and designated VS-TY2662-V1.

What is this component and what does the value inscribed on it mean?


texts: ESP8266 with ultrasonic sensor, booting custom circuit and using gpio0, gpio2 pins for echo and trigger - would this set-up work?

texts:
I am designing a circuit from scratch with an esp12 module.
For booting the esp8266, the GPIO0 and GPIO2 need to be pulled up to Vcc (3.3V) and GPIO15 needs to be pulled down to GND.
I added to my design an ultrasonic sensor.
I am connecting GPIO2 to the trigger pin (which is also pulled high) and GPIO0 to the echo pin (which is also pulled up with an led). Would the sensor work as expected with this set-up?
Or should I use RXD and TXD pins for echo and trigger, respectively?
    +--------------------+         3.3V     3.3V      gpio15
    |                    |           +        +        +
    |      ultrasonic    |           |        |        |
    |      sensor        |           |        |        |
    |    5V   T  E   gnd |           |     +--+-+      |
    +-----+---+--+----+--+           |     |led |      |
          |   |  |    |              |     +--+-+      |
          |   |  |    |              |        |        |
          +   |  |    |            +-+-+    +-+-+    +-+-+
        5v    |  |   ++-+          |10k|    |10k|    |10k|
              |  |   |10|          |   |    |   |    |   |
              |  |   | k|          |   |    |   |    |   |
              |  |   ++-+          +-+-+    +-+-+    +-+-+
              |  |    |              |        |        |
              | ++-+  |              |        |        |
              | |10|  |              |        |        |
gpio2         | |k |  |              |        |        |
      +-------+ |  |  |              +        +        +
                ++-+  |           gpio2    gpio0      gnd
                 |    |
gpio0 +----------+    ++ gpio0


texts: Trigger motor through Raspberry Pi if it's plugged in, otherwise through touch sensor

texts:
I'm trying to design a custom PCB that is powered through USB (5V DC), has a touch sensor, powers a DC motor and can optionally have a Raspberry Pi Zero plugged into it through a GPIO header.

If the Raspberry Pi isn't plugged in, I'd like to forward the touch sensor signal so that it starts the DC motor directly.

If a Raspberry Pi is plugged in, I'd like the touch signal to first enter the Raspberry Pi. The Pi would decide whether the motor should be triggered or not using a GPIO output pin.

What would be the best way to solve such a problem with an electrical circuit? I've tried to figure this out for a while now and can't seem to find the right resources.


texts:
I am reading ADC values on my dsPIC33EP512MU810 when I slide my linearized slide POT. But,what I get is random values, I can read some ADC values but it is not getting updated in each position in the slider. Also,I can't understand why all the buffers are getting updated with different adc values.

Also,the buffers are getting updated randomly for e.g ADC1BUF1 gets updated in the 1st run, then later ADC1BUFA gets updated in the next position in 2nd run and so on. I am using a break point on the line 'reading ADC Value' and debugging it to see the ADC value. Below is my code and also I have attached the output images.

void initAdc(void);
void Delay_us(unsigned int);
int  i, j;
int ADCValue;

int main(void)
{

PLLFBD = 58;/* M = 60*/
CLKDIVbits.PLLPOST = 0;/* N1 = 2*/
CLKDIVbits.PLLPRE = 0;/* N2 = 2*/
OSCTUN = 0;
/* Initiate Clock Switch to Primary Oscillator with PLL (NOSC = 0x3) */
__builtin_write_OSCCONH(0x03);
__builtin_write_OSCCONL(0x01);
while (OSCCONbits.COSC!=0x3);//wait for clockl switch to occur
while (_LOCK==0);//wait for PLL lock at 60MIPS
initAdc();
while(1)
   {
     AD1CON1bits.SAMP = 1;
     Delay_us(10);// Sample for 100 us
    // AD1CHS0bits.CH0SA = ch;  //select analog input channel
     AD1CON1bits.SAMP = 0;   //start the conversion
     while(!AD1CON1bits.DONE);// Wait for the conversion to complete
     //AD1CON1bits.DONE = 0;// Clear conversion done status bit
     ADCValue=ADC1BUF0;// Read the ADC conversion result*/
     Nop();
   }
}

void initAdc(void)
{

/* Set port configuration */
ANSELA = ANSELB = ANSELC = ANSELD = ANSELE = ANSELG = 0x0000;
TRISBbits.TRISB12 = 1; //RB12 as input
ANSELBbits.ANSB12 = 1;// Ensure A7/RB12 is analog
//ANSELEbits.ANSE6 = 1;//AN30/RE6 is analog
/* Initialize and enable ADC module */
AD1CON1 = 0x0004;//bit 10 and bit 2 set to 1
AD1CON2 = 0x0000;
AD1CON3 = 0x000F;
AD1CON4 = 0x0000;
AD1CHS0 = 0x0005;
AD1CHS123 = 0x0000;
AD1CSSH = 0x0000;
AD1CSSL = 0x0000;
AD1CON1bits.ADON = 1;
Delay_us(20);
}
void Delay_us(unsigned int delay)
{
    for (i = 0; i < delay; i++)
    {__asm__ volatile ("repeat #39");
    __asm__ volatile ("nop");
    }
  }


texts: Why do the datasheets of LMH6702 and ADC08200 have different bypass capacitors in the example designs?

texts: The datasheet for the LMH6702 recommends using 6.8uF bypass capacitors on both power supply pins.  The example design in the datasheet of the ADC08200 (Fig. 33 on page 17) instead suggests a 0.1uF capacitor.  Why is there a difference choice?  Which datasheet should I follow?


texts:
I'm building a device that must find its own position on a field (400x400m). Since there will be lot of devices on the field I could not send them their position individually and I want them to be passive (regarding signal emission).

My current plan is to setup 3 rf emitters on the field one master and two slaves. The master on one side emits a signal every second. On the opposite corners are the two slaves emitters, they each send an echo signal when they get master signal. In the device I need to measure the time between master pike signal and slaves echoes. This makes 2 durations. Then send these duration to a micro-controller that will compute position.

I don't need a big accuracy, 1m will be enough. But this means a timing accuracy of 3ns wich is quite a lot. It must be cheap, let say less than $50 each for 20 devices (prototype), and less than $2 each for 10.000 pc (production batch).

What kind of cheap component can measure a time gap with such an accuracy ?

I'm also interested if you know any other solution to this cheap positioning problem.

---------- Edit

I'm not asking for any design service. I explained the context to help other understand the needs. I think my question is quite simple for someone experienced.

Let's ask it another way : Given two impulse signals, how to mesure the time gap between them with 2-3ns accuracy ? I'm thinking of a crystal and a counter. Does it look ok, or plain crazy ?
The microcontroller could calibrate itself using the master signal, so if the crystal frequency is not precisely set it's not a problem providing it is constant over time.


texts: Is 'RFI' a term in active usage, or is it all 'EMI' now?

texts:
I'm studying capacitors in some detail just now, and one of their typical uses, of course, is to bypass high frequency interference at sensitive circuit inputs.

I want to get my terms straight, and it seems like this interference is widely called electromagnetic interference (EMI) and the term radio frequency interference (RFI) is not used or not often distinguished at least.

I understand that, technically, a distinction can be drawn between the two with RFI perhaps being a subset of EMI. But my question is about common parlance and terminology that is effective in practice.

When describing the purpose of a capacitor placed to bypass typical unwanted interference, am I right to use the term EMI by itself; as in "C1 is a 0.33uF metallized polyester cap for EMI bypass"? Or is it useful to maintain a distinction between EMI and RFI for bypass purposes?


texts:
I'm trying to design a power supply for a class D, stereo audio amplifier based on the TPA3250. I have a transformer that will give me 35V on the secondary which I plan to rectify and smooth to supply the below SMPS. Is this circuit suitable to supply 36V up to 10A and am I likely to run into problems with noise?

WEBENCH power supply


texts: Simulation not outputting anything on LTSpice

texts: My group is trying to simulate a UPS for a project and this is what we came up with. First picture is the multisim simulation, second the LT spice simulation, and third it is the output. For the LT Spice simulation - What could be wrong in my circuit for having no output in my graph? Or is there a directive I missed? Did I model the LT Spice circuit differently from the multisim circuit?


texts:
I am working on a project with my MBED microcontroller and I'm running into some snags, because I'm new to it and getting myself confused with how exactly everything works.

I have my MBED hooked up to a 74HC595, which in turn is hooked up to a 7-segment display. I am currently just trying to test the seven segment by creating some sort of counter that goes from 0-9. However, I'm not sure how to do this. Below is my code and how I have it hooked up, I have a few extra declarations in place for the final project, so please just ignore them:

#include "mbed.h"

SPI spi(p11,p12, p13);
DigitalOut red(p25);
DigitalOut green(p26);
DigitalOut cs(p14);
DigitalIn button(p27); //enter
DigitalIn button2(p28); //down
DigitalIn button3(p29); //up

char switchWord;
char record;
int i;

int main() {
  spi.format(8,0);
  while(1) {
    switchWord=0x3F;
    if(button==1)
      switchWord=switchWord^0x06;
    if(button2==1)
      switchWord=switchWord^0x5B;

    cs=0;
    record=spi.write(switchWord);
    cs=1;
    wait(0.01);

    red=0;
    green=0;
    record=record&0x03;

    if(record==1)
      red=1;
    if(record==2)
      green=1;
    if(record==3){
      red=1;
      green=1;
    }
  }
}

Obviously this isn't working how I want it to, I have tried several different ways to get it to count up, and I have been playing with 2's compliment but it's been awhile since I learned about that so I am really fuzzy on it and I couldn't get it to work. Obviously counting up in this set of binary will be different since the 7-segment displays zero when 6/7 LEDs are set to 1, instead of all zeros, so I can't just add the next number or I get a nonsense display. I eventually want to be able to count from 0-9 by hitting the first button, and count down with the second button, but I can't even figure out how to get it to go from 0-1 so if I can get that I think I can get the ball rolling.

I hope this is all clear and I appreciate any help I can get! Thanks!

Alli


texts: Latching circuit that delays the on state for different outputs

texts:
First, I'm very inexperienced in designing circuits like this, so I apologize if this seems trivial.  I'm basically trying to create a startup sequence effect, where LEDs turn on in a delayed order.  Here's the effect I'd like to create.

Push momentary switch once
Wait ~2 seconds, then turn on a few LEDs (latched on)
Wait another ~2 seconds, then turn on a few more LEDs (latched on)
2-4 additional on events to turn on LEDS in sequence
Push momentary switch again to turn off all of the LEDs

I'll be running either 9v or 12v.  I'd prefer to have n-delayed switches (well, at least 5 or 6) chained together with delays between each event (0.5 sec and 5 sec) to create the power up sequence effect I'm looking for.  The delay between two events is constant, but it'd be optimal to have some control over the delays individually.  For instance, the delay between 1 and 2 may be 2 secs, but the delay between 2 and 3 may be 1.2 secs.  The specific timing will take a bit of experimentation.  Each of the on events will have about 4-6 LEDs, so not much power is needed on any individual output.

Seems like a few 555 timers should manage it, but I've gotten a bit lost trying to solve this.  Any help is greatly appreciated.


texts: making different clocks in system generator

texts: I have a circuit in system generator which I cannot retrieve the output signal since it has a high rate. For this issue I planned to use a FIFO at the output. I wanna give the circuit clock to write-enable pin and give read-enable pin a clock with more frequency. So I want to slow down the clock of FPGA, give it to to my previous circuit and then give the clock of FPGA to read-enable pin of FIFO. I asked some days ago and someone taught me using a counter for this issue. So my problem is to decrease the frequency of FPGA's clock by using a counter. I will be thankful if someone give me a picture of the circuit drawn in system generator for this manner.


texts: Led Bulb Flicker when duty cycle is below 40%. What is wrong with circuit?

texts:
I am working on project to dim the LED bulb(Dimmable) with Atmega328. Everything works fine when duty cycle is above 50% but as soon as i am decreasing duty cycle below 50% LED bulb start flickering. Please suggest what is problem with circuit.

Conditions:-
1.> I am generating 12V power Supply and then using lm317 to generate 3.3v from 12v.

2> Using Zero Cross detector with atmega328 which is working fine.

3> If i drive gate of both mosfet from a separate 12V supply instead of my actual supply, circuit is working fine.

Please suggest something....

simulate this circuit – Schematic created using CircuitLab

I have modified my circuit and now its working fine. Thanks for your comments and rectifying my schematic.

simulate this circuit


texts: What is making my DC/DC converter's capacitor to blow up?

texts:
I'm having some capacitors blown up and I am not sure what's the cause of this. It is definitely NOT OVERVOLTAGE and NOT in WRONG POLARIZATION. Let me introduce the scenario:

I have designed a double cascaded Boost converter using this scheme:

Vout can be obtained from: \$\ Vout=Vin/(1-D_\max)^2\$ where \$D_ \max\$ is the maximum duty cycle.

I want to step-up an input voltage of  12V into a 100V output voltage. My load is 100Ω, hence it would be dissipating 100W. If I consider no losses (I know I'm being TOO idealist, calm down), the input voltage source will deliver 8.33A

We can split the circuit into two stages, the first stage's ouput is the second stage's input. Here comes my problem:

C1 is blowing up when the voltage accross it reaches aproximately 30V. C1 is rated for 350V and it's a 22uF electrolytic capacitor (radial) 10x12.5mm. I am totally sure the polarization is right.

The second stage's input current should (ideally) be around 3.33A (in order to keep the 100W with 30V for this stage). I know the current might be higher, but it's a good aproximation for this purpose. The switching frequency is 100Khz.

For some reason the cap blows up and I don't really know why. Of course that when this happens the cap (dead) is hot.

May it be an effect of the ESR? This cap has a 0.15 Dissipation Factor at 1kHz. \$|X_c|= 1/(2*pi*100Khz*22uF) =0.07234Ω \$
So \$ESR=0.15*0.07234= 0.01Ω\$ (DF would also increase for a higher frequency) for C1.

Since L2 is pretty large, I would expect C1 to deliver a pretty constant current equal to the second stange's input current (3.33A) so the power dissipated in ESR is supposed to be around: \$3.33A^2 * 0.01Ω = 0.11W\$

Can this make it too hot and explode? I doubt it....

Additional information:

L1 is about 1mHy
L2 is about 2mHy
D1 is a schottky 45V diode
I tried two different capacitors: 160V 22uF that blown up, and then I tried the 350V 22uF which also blown up.
Measuring the current in the cap would be difficult due to PCB layout
Both the first and second MOSFET has a small snubber RC network. I don't think it could cause any problem in C1.

I am waiting for your ideas!

EDIT n°1=
L1 is pretty large, ripple is only 1% of the rated input current (let's say 100W/12V = 8.33A) so que can assume it's almost like a constant current at the input of stage 1. For stage 2 inductor current ripple is less than 5%, we can also think it's a constant current). When MOSFET 1 is turned ON, around 8.33A goes through it, but when it's turned off, that current (we said "practically constant") would go through D1. We can say current in the capacitor would be \$ I_{D1} - I_{L2} \$ . Then we finally find that the peak current in C1 must be in the order of \$ 8.33A - 3.33A = 5A\$. Pretty much current! and it would dissipate \$5A^2 *0.01Ω = 0.25W \$ ... but looks not so much power dissipated in the ESR.

As someone said, I might also consider the internal inductance of the cap, but i think this wouldn't be a cause of power dissipation (we know inductors store energy but don't make it into heat) Anyways, despite of the calculation above was very simplified and it might be a little higher power dissipated, I still wonder if it's enough to make it boil and explode!


texts: Is using a 50Hz rated battery charger at 60Hz safe?

texts: What would happen if I used a battery charger rated for 230VAC 50Hz input here in USA where we use 60 Hz?  Would it be ok?  What side effects may happen because of the mismatch in input frequency with the specs of the charger?  Is the reaction of the magnetic core of the charger to the different frequency the only concern I should have?  What might this do long term to the charger?  Might it fail prematurely?  I would use 230V 60Hz input on this charger by using a pair of phase locked (but reverse phase) 115V 60Hz lines so it would be a true 230V 60Hz 15A capable power source.


texts:
First things first - I am a complete novice. Thank you in advance for your help.

I bought a motor second hand, though it has never been used. My aim is to have it run my table saw.

What I know:

As it is currently wired, I've been able to work out the it will run in a clockwise direction (I will change this)
I know where to put the earth

What I don't know:

Why does my motor only have one capacitor? All the others seem to have two? Do I need to do anything about this?
Why does it have a circuit breaker?
And most importantly, where do I put the neutral and live wires?  I have seen one diagram with the the live going into the circuit breaker and the neutral  being connected to the U1 point, but the connections diagram doesn't suggest this.

I know that verions of this question have been asked but I've not been able to find the specific example of a single capacitor/ circuit breaker motor.

Thanks again.


texts:
I am making a standalone battery powered arduino project which uses nRF24L01+ for radio communication. nRF draws 20 mA current max. Can I use 3xAA cells along with 2 diodes (which drop 0.6*2 = 1.2 V) to get 3.3 V source for my nRF module?

I will be keeping my microcontroller and nRF module in sleep mode most of the time. All it has to do is to wake up after a certain interval of time (maybe 2 to 5 seconds), communicate to a central radio server and go back to sleep.


texts: Is there an industry standard serial hardware identification protocol?

texts:
Say I have several microcontrollers connected serially over several COM ports. I want to identify which microcontroller is on which port. Say, μC1 is on COM1 and μC2 is on COM2.

Is there any industry-standard, or at least widely accepted, method for sending an ID request and receiving an ID response? Something like:

CPU: "IDENT" --> COM1
GPU: "IDENT" --> COM2
COM1: μC1 --> "1"
COM2: μC2 --> "2"

And we now know μC1 is on COM1 and μC2 is on COM2.

Thank you!


texts: In which way can I use operational amplifiers to amplify XLR signals?

texts:
I'm asking myself, how I can use operational amplifiers to amplify XLR signals? Let's say my XLR input gives me GND (1) Signal+ (2) and Signal- (3).

Can I simply connect 3 and 2 to my operational amplifier and than take the output (4) from my operational amplifier, combine it with the GND (1) and connect it to a speaker?

Are there any circuit plans with operational amplifiers that show how to build a preamp? (XLR -> XLR or XLR -> Cinch)


texts:
I'm working on implementing Armstrong Modulator . I successfully implement the narrow band block but I'm struggling into finding a solution to multiply the frequency of my modulated signal .
Any ideas ?


texts: Can I connect GPS module (NEO-6m) to bluetooth module HC-05 directly?

texts:
Since I have poor GPS reception in my car I thought I could forward GPS data from GPS module to a phone via bluetooth.

I am using NEO-6M GPS module and HC-05 bluetooth module.

At first I was thinking about using Arduino, but then it occured to me that both GPS and bluetooth modules are operating 3.3V UARTs on respective inputs and outputs. Therefore is there any downside in connecting their TX and RX lines directly? By default both modules use 9600 baudrate so I don't think any configuration is needed.


texts: Finding the input resistance of an oscilloscope

texts:
I'm having a little trouble understanding how to do this problem. So an oscilloscope measures a battery voltage of 1.5V, and when a 1M(ohm) resistor is put in series, the oscilloscope only measures 0.75V.

I'm a little thrown by the term 'input resistance'. Is this the same as input impedance here, or something else?


texts:
I have the following schematic that is supposed to rectify the signal going to a VU meter and also trim it, so the user can adjust the position of "0dB".

What I don't understand is why and how the resistor is connected in that way, shorting legs 2 and 3. Is this working as a simple voltage divider? Or just a rheostat? How does it work and how does this trim the actual display?

The schematic is preceeded with a buffering op-amp.


texts: DC filter for a spectrum analyser - cut off frequency

texts:
Most of the available spectrum snalysers do not want a DC component to their 50 ohm input. But how low should the cutoff frequency be? Also which parameters indicates that clearly in the datasheets? As this clearly depends on the applied amplitude.
Lets say for an example a first order high pass filter with fc= 1 Hz and Rinput=50 Ohm:
C=1/(2pi*50 Ohm * 1 Hz) = 3183 uF


texts:
I just recently stumbled across LDOs and understand that they are used to regulate an output voltage. I understand that they require a differential amplifier, a reference voltage, and a pass element of enormous size.

However, I'm unclear as to what inputs can be fed to an LDO. For example, could I feed it a sinusoidal input and expect a dc output? Could I discharge a capacitor through an LDO and see a dc output at the LDO output? Will an LDO be able to take any input and output a dc voltage?


texts:
I am struggling to understand how do I get a pulse interval encoding scheme implemented in terms of hardware. Is there any source of information available explaining the circuit diagram of the same?
I am using a S2LP transceiver IC and it supports Manchester, NRZ, FEC and 3 out of 6  encoding schemes but I would like to use PIE encoding scheme instead.
Any help/suggestions would be appreciated.
Nilesh


texts: What is the maximum allowable load capacitance for 74HC04?

texts:
Does anybody know the maximum allowable load capacitance for 74HC04? In the datasheet,  nothing is mentioned in the "Limiting values" section. Some of the dynamic characteristics are given for a load capacitance value of 50 pF, but the limiting value is not mentioned. Any ideas?

Abhishek


texts:
In my career I've often encountered signals that are active low (Reset being the most common). I've even seen interfaces where all control signals are actively low.

To me, this is very unintuitive and confusing.
Why is there ever a need to use actively low?
Is it merely historic or is there actual gate count / power concerns that explains it?


texts: How to increase the rated output voltage/current by connecting multiple op amps?

texts:
Is there a way to increase the power output from connecting multiple op amps?

My guess is that connecting the op amps' output in parallel will increase the rated current, and connecting power supplies with a common ground on the op amps to increase the voltage. For example, +15 V to first op amp, then -15 V to second op amp; the saturation of the parallel connected op amps should be 30V?

I'm using THS3202 and looking for driving a \$50\Omega\$ load at around 50 W

I have seen the datasheet and all the rated/maximum. How can I connect multiple op amps to increase the resulting output wattage?


texts:
As suggested in an answer to an earlier question of mine, bonding to a laptop can be done by connecting an anti-static wrist strap to the ground of an USB-port. (After disconnecting the AC-to-DC adapter.)

At which locations should there be a 1E6 ohm resistor? My quess: at A and B.


texts: Is it meaningful to describe an IGBT as desaturating?

texts:
I've heard IGBTs described as desaturating if too much current passes through them, particularly in the context of drivers with desat protection. My understanding of an NPN BJT is that it is in saturation mode as long as the B-E voltage and B-C voltage are positive. Obviously this definition does not apply to IGBTs. The curves on every IGBT data sheet I've seen show a typical junction drop relationship between voltage and current collector-emitter when the device is gated on. What happens off the edge of the sheet, though, is not clear to me.

I see two possibilities.

The curve doesn't change off the edge of the sheet. The only disadvantages to running a given device at higher currents than spec'd are thermal, and the general rule that running off the data sheet is not recommended behavior.
The curve does change off the edge of the sheet; put too much current through the device and it goes into an analog mode. The losses start going up even faster than extrapolations from the given curve would indicate, leading to rapid catastrophic failure.

Which is the deal? Is there physical meaning to describing an IGBT as desaturating, like a BJT? Or is it just a way of saying "instantaneous overcurrent"?


texts: What is the equivalent thevenin resistance of a digital output port on an Arduino Uno R3

texts: How would I determine the thevenin equivalent resistance?


texts: Anyone got 95812 HRZ W712PK regulator datasheet?

texts: I would like to know about 95812 HRZ W712PK's datasheet or pinout diagram. I googled the datasheet but it only has one page and doesn't include pinout diagram. so guys please help ...


texts: In our village, the power supply is unstable. Sometimes it goes weak, sometimes not. You can tell it by our bulbs, it goes dimmer when the power is weak. Our monitor now shows some green and red wires in the screen, kinda like a 3D screen without a 3D glasses. According to the technician, it was due to the unstable flow of current/power in our village. Now, I have a laptop, and I bought an Auto Voltage Regulator, will this prevent my laptop from being damaged by the unstable flow of currents? Or should we buy our own generator?


texts: Finding maximum sink and source currents from datasheet

texts:
How can I find the maximum sinking and sourcing currents of different pins in a microcontroller (namely 8051) from its datasheet?
Edit: I have downloaded and looked at the datasheet, I just can't read this information from it.


texts:
I want to use a nodemcu to water my plants. I connected a pump with a 2N2222 transistor (I know i should add a diode and a pull down on the gate). The pump is DSL370 and when it is off i measure 4.4V on the Vin pin while using a 2A charger connected to the USB port. When the pump is active, the vin voltage drops to 4.1V and the LCD becomes hard to read. I measured the current the pump uses and it is 300mA. What is the reason for the voltage drop? I thought the charger should be able to handle it.
Also, as i saw at
http://henrysbench.capnfatz.com/henrys-bench/arduino-projects-tips-and-more/powering-the-esp-12e-nodemcu-development-board/
The power from the USB is connected to the Vin via a diode so the Vin and the esp8266 power should not affect each other.


texts:
I have a question about the sign of Δt :
Why is Δt in in this one positive

And negative for this one below  ?


texts: Can this gyrator handle high current and/or high voltage?

texts:
Since I first got introduce to the Antoniou Inductor while in university, I've always been amazed at it. I've never built or used one, but I am thinking about using it to simulate an inductor for a future project.

Below is an image of the Anoniou Inductor.

My circuit will be pretty simple, as shown in the image below.

simulate this circuit – Schematic created using CircuitLab

My source will either be a fixed frequency +/- 30V square wave or a fixed frequency +/-1A square wave.

Question: Can I use this circuit with the given source voltage/current ?

I think it might be ok, if my opamp rails are high enough, and the passives between opamps are rated appropriately.


texts: How do I add a tuning potentiometer to modify the incoming control voltage of an XR8038?

texts:
I have been working on designing an analog synth and have decided to use an XR8038 as my VCO. If I wanted to add a tuning modifier would this configuration I made be okay?

P.S. Would I need to attach a LFO to this VCO to get it working? If so how should I approach it?


texts: I have a fairly simple circuit with an Arduino and a SA818 RF module, I'm providing 3v3 power to the SA818 via two series diodes (dirty I know) and am communicating using software serial, of which the TX line from the Arduino runs to the RX of the SA818 using a resistor divider to drop it to 3v3, I have a small speaker connected between the SA818 AF output and ground. everything works but the noise (pulses) when the TX line is transmitting completely swamps out the audio from the SA818. I have placed a capacitor between the AF out and the speaker but it has not helped. I know this is a bare minimum circuit but does anyone have ideas of how to isolate the UART from the audio?


texts: We learned in class that the number of independent KCL equations is N-1(N-number of nodes) and the number of independent KVL equations is B-(N-1) (B- number of branches). Thus we have B independent equations and we can solve the circuit for the currents. What I don't understand is how can we know for sure that the B equations are independent? The union of two independent sets of vectors is not necessarily also independent.


texts:
I have a large LED array (huge, actually). It's 38 rows x 76 columns (2888) LEDs in total. The LEDs are 3mm, rated at 2.0 forward voltage and 20mA. The 38 rows (positive) are multiplexed using TPIC6B595N shift registers. However, the rows are divided into sections of 8 for a total of 5 sections with the last section containing only 6 rows. Each section has its own ground lines. Then, these sections are multiplexed in parallel - this is done so that the LEDs have a reasonable duty cycle of 1/8 instead of 1/38 to avoid losing too much brightness.

Since the TPIC6B595N registers can only sink current, they are connected to PNP transistors on the positive side to source the current. My problem is I'm not sure how to distribute the power properly. By my calculations, 7.6A (76*5*0.02) are needed to power the LEDs since a maximum of 76*5 LEDs could be on at any given time. Furthermore, a total of 55 (ceil(76/8)*5) shift registers need to be powered, and I think the datasheet suggests 150 uA for each register so the current needed for the ICs may be insignificant. Each sink needs to have a resistor (that's 5 * 76 = 380 resistors), and I need some guidance in selecting an appropriate resistance based on the power conditions. Last but not least, the array is driven by a Raspberry Pi which will need 800mA itself.

I am thinking of using a standard supply like 5V 10A to power the LED array, but I don't know how to go about distributing it appropriately - I don't want the LEDs to burn if only a few of them are on so how do I prevent them from drawing more than 20mA of current? How would I go about distributing the power over various components if they have different voltage and current ratings?

Note: My background is first-year computer engineering, so please bear with me and guide me if you think there is a flaw in my design.

Here is my best attempt at a diagram:


texts:
Hi I'm a DIY enthusiast and I got stuck with the circuit that I designed.
The counter is getting very hot from the moment It's powered up.
In my setup the 330Ohm resistors at the outputs  are connected to GND via a led for each resistor. (not the relays)
I omitted the resistors at the parallel in inputs, and connected these directly to GND.
Please tell me what I've done wrong.
The components are soldered on a PCB that I had made by JLCPCB

==========================================================
In response to the comments below:

The Dark mode is the default in Eagle that I use. I'm sorry if the schema is hard to read, I'll change the colors in the future. Thanks for additional image.
The circuit is a 6 bit binary up/down counter. It needs to count upon button pushes. The logic gates around it are there to prevent underflow and overflow.
The circuit will operate at a frequency between 1 and 10 Hz.
It's getting verry hot to the feel, right after starting up. (with zero leds on) So after a few secs I switch it off.
Eventually circuit will control, through driver circuitry, 6 relays and the leds. On a bread board the counter could drive the leds while counting) I did not setup the full circuit though as I it was space confined and it got messy with all those wires.

For the logic part:

!PE = !(UpButton & DownButton)
!CET = !(UpButton XOR DownButton)
Up = !(Q0 & Q1 & Q2 & Q3 & Q4 & Q5) & UpButton
Down = !(Q0 | Q1 | Q2 | Q3 | Q4 | Q5) & DownButton
U/!D = Up

With ! == NOT, &==AND, |==OR