texts:
I am creating a simple circuit in order to amplify the signal from an electret microphone and then add a 2.5V bias to the signal.
The problem I'm having is that the signal from the mic is distorted as it leaves the op amps.

With an oscilloscope I have measured the signal from the microphone when exposed to 440 Hz sound and the wave looks like a perfect sine just as expected.

However once the signal passes the part of the circuit to amplify the signal the sine wave starts to get slightly distorted.

After the signal has passed the circuit of the inverting summing amplifier the signal gets even more distorted.

This is the circuit I use to amplify the signal:

This circuit leads to a 20 uF capacitor and is then followed by the following circuit to add the 2.5V DC bias:

where all resistor values are the same. This circuit uses the same LM324 as the amplification part of the circuit.

The resulting waves at 440 Hz look as follows:

This is after both the amplification and the summation. The distortion of the sine wave starts happening after the amplification, and gets more obvious after the summing op amp.

I have no idea what can cause this and hope somebody can point me into the right direction.


texts:
I was fixing an ultra cheap home router few days ago and noticed that it had vias marked TP_12V, TP_3V3, TP_GND and similar. The problem turned out to be leaky electrolytic crapacitors in the buck converter and the vias really helped debugging that, but that's not the main point of this question.

What I really wanted to ask is in general is there any reason why not to use vias as test points? All test points I've previously seen were exposed copper pads which were helpful, but were a bit difficult to use because I'd need to connect the scope probe to a flat surface. Here vias were just the right diameter to hold the tip of standard multimeter or scope probe in place without need for any external tools.

I suspect that vias would be a little bit more expensive than normal copper test points (but again, this was found on a sub $15 unit) and that they would be less durable than simple pads.

I suspect that the bed of nails devices used for production testing would need to be a bit more precise for this to work nicely, but I don't know how big problem that would be.

So did I miss any reason why to use copper pads instead of vias for test points?


texts: Question for increasing the Flux of an electromagnet

texts:
A.   This question has two parts.   The first part involves amperes law concerning the strength of an electromagnet as measured in Tesla.   Amperes law states that the strength of the B field of the strength of the electromagnet is determined by ampere turns and current in said turns known as MMF.

Yet amperes law is based on the permeability of the wire used for said ampere turns of one.  What if we used a permeability of 1000 times that (iron).   Wouldn't the magnetic field of the current be amplified for each turn of an electromagnet if a high permeability wire were used instead?   Would that not increase the strength of the electromagnet by thousand fold?

B.   If an electromagnet has a core made up of ten individual iron wires, each insulated from the other, but part of the same magnetic circuit with parallel reluctance, wouldn't each wire magnetize, and seeing how magnetic fields are cumulative, would this not create a stronger total Flux than one core of equal cross area?   If a single core of same cross area had 0.1 Tesla but with the core with ten iron wires and each magnetic field is cumulative, it's total field strength would be 0.1 Tesla x10?  The core with 10 wires all have the same 90 degree winding around all ten so to each wire it appears the same ampere turns or MMF.


texts: Failsafe for home automation with Raspberry Pi

texts:
I have a Raspberry Pi driving a home automation system. I have connected a bunch of lights to the network. The GPIOs of the Pi connect to a relay board that switch the lights on and off. What I need is failsafe + alternative switches. These switches need to work even if the Pi fails, and they need to be usable when the system is operational (in 3 way switch, Pi switch XOR manual switch = bulb state fashion).

What is the best/standard solution for this? Three way switches would work, but then the Pi loses the state of the devices. I could get the state of the lamps by setting up a DC adapter in parallel to the bulb input, effectively measuring voltage which could feed back to the Pi telling me the true state of the bulb.


texts: How to calculate the PI model equivalent transformer parameters

texts:
I have a power transformer with the transformer ratio 200kV/100kV, 100MVA rated power, and specified R = 0.001 p.u., X = 0.05 p.u. For a calculation I have to make, the literature I am using is referring to the "PI" model of the transformer:

How do I get the series impedance (R + jX) from the plate values? Or are R and X in the image the same as the plate values?


texts: My query is that..At node B the voltage is 11.7 V ..and at node A it is 11V according to text, but it should be two diode drop below the voltage at node B i.e it should be 10.3 V(because 0.7V voltage is getting dropped at BE junction of Q1 and across D1) please explain why i am having a contradictory idea ???


texts: It's my first time using LTSpice that was required for us to use but our prof didn't know that most of us haven't used ltspice yet. I already have done the schematic diagram but i dont know how to input the parameters, can someone pls help me?


texts: Way to mitigate parameter dispersion in NMOS attenuator

texts:
I am building an automatic gain control for a subMHz signal, which comes in the 30-120mVpp range, using a NMOS as VCR. At the output, ideally, signal should be 'compressed' around +-Vpeak_detect_th . I decided to use a NMOS instead of the several circuits using NJFETs I have seen around, like in this circuit ( https://www.engineersgarage.com/circuit_design/circuit-design-automatic-gain-control/) because I can save an inverter stage in the peak detector.
After this, a High gain amplifier is used together with a peak detector at its output that controls the Vgs swing. With bias_mosfet I set the Vgs at Vgs(th) and the control signal is positive 0-800mV. So far is working good in simulation, with proper adjusting of the bias and the ratio_resistor/amp_gain balance. The problem I see is that this is designed assuming that Vgs(th) is fixed but thats not the case for real transistors, which have dispersion.
For the nFET circuits a usual practice is to add a feedback network so the gate gets Vds/2 to improve linearity.
What would be a way to mitigate the NMOS Vgs(th) dispersion in this curcuit? Without having to adjust the bias per circuit in fab?
Which NMOS is better for this application? Enhanced? Depletion?
As of now I am using 2N7002W From On Semi, which meets 2 important criteria, cost and smt.
Any suggestion on real parts?


texts: 2 ideal op amp circuit design, find voltage Vp

texts: I need to find Vp giving the values below. These two opamps are ideal with negligible current input to them. I'm doing KCL across the circuit and then switching to voltage/resistance but I'm not getting the right answer.


texts: Current gain characteristics versus Collector Emitter voltage. Where is the transistor saturated? Can a transistor be saturated with a VCE of -10V?

texts:
I'm fairly new to transistor usage and determining stages of operation for a BJT. However, from what I've learned, in order for a BJT to be saturated, both junctions need to be forward biased, and that in saturation, an increase in base current does not equal an increase in collector current.

However, looking at this particular datasheet, and specifically this graph, they have current gain versus different collector-emitter voltages.

Can I assume that saturation on this graph occurs when the DC current gain starts dropping, or below the knee of each line? For example, at 200 mA with a VCE of 10V, is this transistor saturated since the current gain is dropping?
If #1 is true, how is it possible that the transistor is in saturation with a VCE that is greater than 1 V? I thought since in saturation, both diodes are forward biased, so that the emitter-collector junction has a relatively low voltage drop (below 0.7V). Am I missing something here in how I am interpreting this graph?

Help greatly appreciated! Been bothering me all day.


texts: Does current split when we connect battery in OR configuration

texts:
Please check the below circuit. Edited the circuit as told.

I have connected two batteries (Max 3A) in OR configuration to the load as shown below.

Once, the power is ON, does the current (assuming the load current = 600mA) split as 300mA and 300mA from battery and battery 2?

or how does the current split?

simulate this circuit – Schematic created using CircuitLab

Figure 2. Schematic for OP to edit and complete showing the battery and load connections.


texts: Recharging a 11volt rechargeable battery using multiple 5volt solar panels (Size: 53*30*3mm)

texts:
I want to make a circuit using solar panels.
I want to recharge e 11Volt 1200mAh rechargeable battery with my solar circuit.
The solar panel I will be using is 5volt, 30mAh.
So my question is, how can I construct the solar circuit- how should I use multiple solar cells parallelly and serially to ensure that the circuit generates more than 11 volts.
1) should I just serially connect 3 solar cells to make 15 volts, 30 mAh, should there be any other electrical components?
2)after establishing the circuit, should I just connect the two ends of my solar circuit to the positive and negative of the rechargeable battery? Or should there be any transistor, diode or something else in the middle to ensure the flow?
3)can I use the battery to power an arduino at the same time the battery is getting charged? Or should the charging and discharging be in a different time?
4)If I have to do charging and discharging at the same time, what measures should I take to ensure it?
 I will highly appreciate if any of you can come forward and help me. And if you have a picture of the said circuit or any link, I will be grateful if you attach it to the replies.


texts: How to determine total circuit voltage and individual component resistance for a series circuit

texts:
This is a question from someone who has just started to learn electronics. I'm a bit confused

Lets say I have a series circuit with three lamps. Lamp 1 needs 1V, lamp 2 needs 2V and lamp3 needs 3V. I therefore assume I need a 6V battery for this set up. However if I only have a 12V battery, presumably I would need to insert a resistor to reduce the voltage so given I need to 'remove' 6V from the circuit. This would then be 6/Current= Resistance. Do I assume that I would know the current from the battery and that this is the current throughout the circuit. Also does it matter where I put the resistor in relation to the lamps?


texts: How does a car with keyless entry know where the key is?

texts:
If I hold the car key and touch the handle on the door, the car locks the doors. But if I leave the key inside the car, it won't lock itself.

How does the car know where the key is located? What mechanism does it use to triangulate the key? It can't be using ultrasound since ultrasound doesn't go through objects and is directional. It can't be radio wave either, unless the car can accurately measure down to nanoseconds.


texts: Effective transconductance of a CMOS inverter

texts: If we have a CMOS inverter operating in its' linear region, what would be the effective trans conductance of the inverter?


texts: Why does it make the composite amplifier circuit stable?

texts:
I reversed engineered a headphone amplifier based on composite topology with opa1612 and tpa6120a2.
There's two capacitor and one resistor (circled in red) that I don't quite understand. I know this is for stabilizing the circuit, but don't understand the theory behind it. could someone give some hints/pointers to help me understand it? Thanks!


texts: Dynamo - Reversing the rotation of the shaft

texts:
I'm having a debate with a friend. He claims that if you change the rotation of the shaft of a dynamo the output DC current changes direction. I, however, claim otherwise. The way I see it is that a dynamo rotates a coil inside a magnetic field, this produces an AC sine wave which then gets rectified to DC by the commutator. If you rotate the coil in the other direction it still produces AC and then gets rectified to DC in the same direction as if the shaft were rotating in the original way, right?

So who is correct? If it's my friend then why does the DC current change direction?

Any help is greatly appreciated.


texts: How to power up 50 LEDs? (DIY 'fireflies' project)

texts:
I want to install lots of tiny LEDs lights in my garden (at least 50).
I DON'T want high voltage cables in my garden so I am thinking in getting a high power, low voltage transformer to power up these LEDs.

For example, I have two 24V/1.25A (30W) power supplies from Canon printers.  Let's say this is a small scale test. Later I could use a PC power supply for 50+ LEDs.

The LED I will use is 1W but I want to run it at about 3.1V/0.1A because at this current it doesn't require a heatsink (it runs at under 37Celsisus - I hope in summer it won't get much hotter). So, I can have 12.5 branches, each branch will have 8 LEDs in series, so 2.4W per branch.

Is this a good design? Any alternative idea is welcome as long as it doesn't involve carrying more than 25V per underground cables.


texts: calculating maximum sense speed of amplified phototransistor circuit

texts:
I made the following photo-transistor circuit to sense light with the exact parts shown. Resistors are 5% tolerance 1/4 watt. The circuit does work, but what I would like to know is how do I calculate the bandwidth of the circuit as it is now? By bandwidth, I mean the baud rate (bits per second).

From what I understand from the internet, transistors exhibit miller effect capacitance and logic gates experience propagation delays so is it as simple as multiplying the total miller capacitance by the total resistance of all resistors then adding the nand gate propagation delay? or am I missing something?

VCC here is +5VDC fed from a regulated power supply.

And if my theory is correct, then could I convert the 2.2K base resistor to 100 ohms safely and gain better speed without anything overheating? The reason why I want the resistor in the first place is because in the actual project, the photo-transistor will be manually plugged in after the rest of the circuit is complete and if some goof connects a pin to VCC and its not the ground pin, then the base resistor will be connected to VCC which to me is better than a direct connection from base to VCC.

Sorry, but the people I work with are newbies.


texts: How to explain how the DIAC and TRIAC works in a digitally controlled fan regulator circuit?

texts:
There are two version of the circuit that do the same thing. One with capacitor, and, one without.
The schematics below depict the circuit needed for diac/triac activation properly. (I have missed out a few components for achieving the full wave rectification; ignore that).
1. With capacitor/resistors

2. Without capacitor/resistors

Both circuits do the same dimming operation. Assume there is a AC fan connected in the output end. I came across this video which explains a traditional fan regulator circuit. However, I am unable to explains what happens in circuit #1.
How does the capacitor in circuit #1 work? What is its function? Is it for smoothing the chopped output AC (which goes into the fan)?
I am hoping someone explain circuit #2 with reference to #1. So which of these circuits are ideal for a fan speed regulation?


texts:
I am a beginner, and I have a school project that requires me to use Arduino or any other microcontroller to control an LED light.

After some research, I found out that not all LEDs support dimming, and I would need to buy LED and a LED driver that supports TRIAC in order to make dimming works.

I found a tutorial online that uses Adruino and TRIAC to dim the lights bulb, but I am told that it wouldn't work with AC LED as the circuit in the tutorial is deisgned for resistive loads only. Link to the tutorial: http://m.instructables.com/id/Arduino-controlled-light-dimmer-The-circuit/

Is there anyway that I can modify the circuit in the tutorial to make dimming works with an AC LED? Perhaps attach a LED driver that supports TRIAC to the PCB, then connect the LED to the driver? Or do you suggest me do it using another method?


texts: What is the use of transformers with 3 pairs of wires?

texts: I found a device which has a ferrite core and 3 coils on it. It looks like some type of transformer. What would be its use? I found it in a compact fluorescent lamp.


texts:
I'm going to build a coffee heater for a school project.

I know I have to take advantage of the Joule effect (Joule heating). I am restricted to using a resistance between 330 Ω and 1 MΩ. The voltage supply is 5 V, via USB connection.

If I use resistors, then the circuit won't get hot. If I use diodes, their temperature will increase but not enough.

How do I generate enough heat in the circuit to heat coffee?


texts: Calculating an operational amplifier with changing power source

texts:
I've been stuck since days to calculate an operational amplifier circuit used as an under-voltage protection. At first my design:

simulate this circuit – Schematic created using CircuitLab

The main problem here is the changing supply voltage \$V_{dd}\$. It slowly varies from 9V to 17V and the other way round (battery). I would like to have the switch occurring at 10V and 10.5V respectively. For calculating the hysteresis I would use

$$
\Delta U_e = \frac{R_2}{R_{1}}(U_{a,max}-U_{a,min})
$$

Ignoring the small output swing from rail \$U_{a,max}\$ is essentially \$V_{dd}\$ and thus varying. So there are two solutions one for \$U_{a,max}=10V\$ and one for \$U_{a,max} = 10.5V\$. Assuming a 300k resistor for R1 and a 14.6k resistor(not existing) for R2 the error should be pretty low. The main problem comes with finding an analytical formula for calculating the potential at the input of the opamp \$U_+\$. Since \$U_+\$ is depended on \$U_{out}\$ I don't know how to calculate the voltage divider R4 and R5 to get the switching points as mentioned. (For the diode i chose a 6.2V)

Thx in advance


texts: Multiplexing 12 sensors to be read with 6 ADC channels

texts:
I'm buying this Xbee chip.

But it only has 6 ADC pins and I have 12 sensors! Can I multiplex my 12 inputs? How hard is it to do this? I don't want to have to use 2 Xbee modules for power/cost reasons.


texts: How to remove byte to byte delay using MCP2210

texts: I am using a Microchip MCP2210 USB to SPI converter, however during operation, there is a delay between the sent bytes. Is there a way to remove this ?


texts:
I'm working on a project, it's basically a hand-drawn paper keyboard based on capacitance.

I was thinking I can multiplex the different lines with shift register (74HC595) and switch (4066), and as I've got a lot of these here I gave them a try. But apparently not...

So I'm looking for a solution.

I've already found that : Multiplexer for Capacitive Sensors (MUXC01)

Can you confirm that this component could work or do you have any better idea about how to multiplex these keys ?


texts:
I'm trying to design a circuit to charge a capacitor bank with constant (limited) current and then discharge the capacitors through an LED. I've come up with the circuit in the schematic below, however looking at it now, I'm not sure if it's going to work the way I want it to, due to the 2 N-MOSFETS being in series (along with a small resistor also).
What I want is to slowly charge the capacitors at 128mA (blue path) up to 5V, and then use a digital 5V signal to switch on the MOSFET Q2, which will primarily discharge the capacitors through the diodes at high current (black path). Once the capacitors are discharged sufficiently, it should also keep the current coming from the power supply through the LEDs limited to 128mA.

I have some concerns since I've never done or seen an arrangement of MOSFETS like this (even more so with one of them acting as a current limiter). Will this affect the operation of the MOSFET(s) and if so how?


texts: Discharging a capacitor through a resistor and an LED in series

texts:
Suppose you have a capacitor of capacity \$C\$ and initial voltage \$U_0\$, a resistor \$R\$ and a LED with threshold voltage \$U_S\$ (\$U_0 > U_S\$)  in series.

Now I want to calculate duration \$\tau\$ where the led is lighting.

My intuition was that the effect of the LED should be small in this case and I can use just the usual formula for capacitor discharge \$U(t) = U_0 e^{-\frac{t}{RC}}\$. Then I guess that the LED is lighting until the voltage reaches the value \$U_0\$, i.e. I have to solve the equation \$U(\tau) = U_0\$ which leads by elementary algebra to \$\tau = -RC \ln\left(\frac{U_S}{U_0}\right)\$.

However I am not sure if my intuition is correct and how to give reasons for it. So is there a good simple argument, why the approximation above or a similar (correct) approximation is valid?

My second question is about how to derive this (or a similar correct approximation) from first principles.

My idea was to set up a differential equation like follows:

$$
C \frac{dU(t)}{dt} = -I(t)
$$

And put for \$I(t)\$ the formula for the current through the diode I found on http://en.wikipedia.org/wiki/Diode_modelling#Explicit_solution which involves the Lambert-W-function. However then it get's pretty complicated and I don't know how to solve this differential equation and how to make reasonable approximations (at best with bounds for errors).

PS: I have found this paper: http://www.uncg.edu/phy/hellen/HellenAJPAug03.pdf which discusses the problem in the case when only a diode is present. But it doesn't take the resistor in series into account.

Edit: If I assume approximately that the diode has the voltage \$U_S\$ all the time, after solving the corresponding differential equation, I end up with something like \$U(t) = U_S + (U_0 - U_S) e^{-\frac{t}{RC}}\$ which seems to make no sense because \$U_S\$ is a lower bound (which was actually already in the assumption...). So it would be great if someone could really clarify all the mess here...


texts: What's the maximum current at every output of this driver?

texts:
I'm using the driver DS26LV31T and need to know what is the maximum output current for the output pins (P,N, for example pins 2,3).

I'm confused because I'm not sure where to take that information from.

On the one hand, this is from the Absolute Maximum Ratings:

While I don't like looking at the Absolute Maximum Ratings, to me it seems that each output pin can handle an output current of + - 150mA.

On the other hand, when I look at the Electrical Characteristics, I don't see anything like what I'm looking for, but when looking at the test conditions, I do see this:

I am looking at the Io >= 20mA. I suppose the answer is no, but does this mean the maximum output current is 20mA?

Maybe I'm looking at the wrong places for this information?


texts: Board with MCU with USB controller + USB connector how can i have 2 USB ports

texts:
I have a board with a MCU which has USB controller + USB connector i need 2 usb ports. How can i have it with minimal or without any modifications to the board. something like simple usb hub for PCs etc
both of the USBs will be used for write/read to FLASH.
board also has I2C, 2 GPIOs
MKL25z128 is MCU


texts: Reverse engineering old record player schematic

texts:
So this is a loaded question I know, but I'm stuck and I don't know where to go from here...

My mom has a super old record player.  It's build into a bright orange suitcase which is pretty cool.  We pulled it out and cleaned it up, and put a new record on it.  Faint music can be heard, but the volume doesn't do anything.  I assumed the amplifier wasn't working, and told her it would be easy to fix.

How hard could it be figuring out a circuit made in the 70s???

Well, here is the schematic I've pulled (painfully) from the pcb.  Some of the values don't make sense, but it's the best I got.  The two left transistors are covered by metal, so I don't know if their PNP or NPN.

I have no idea how this works.  It's not like any amplifier I've learned about.  I've tried modeling it in EveryCircuit, but it's obviously wrong somehow.

Does this look familiar to anyone?  Any help would be greatly appreciated.

EDIT:

Here's a picture of the bottom side of the PCB.

The top side is a little bit trickier as you can see.  The POT/switch is huge, and it's riveted to cardboard stuff.  Here's an attempt.  Let me know if you want any more angles.

Update:

Man you guys are fast!  Looks like I got the transistor pinouts wrong.  Figures.

I just checked out the POT, and as far as I can tell it is working... which I assume means one of the transistors is compromised?  Thanks for the tips on the flux and solder joints, I'll try cleaning those up.  We'll see how well 40 year old solder reflows...

Now that I have the proper schematic, I'll try simulating it later today.  For those that already have it in LTspice, do these voltages all look consistent?  They were measured with a DVM in DC mode...

Plot twist... If I put my finger on the needle input, I get feedback.  Turning the POT does adjust the volume of the feedback!


texts: How do I solder "cable shoes" onto a circuit board?

texts:
I've got a timer (http://m.ebay.co.uk/itm/221094671882) with male cable shoe connectors (see image). I've connected the timer with other devices using wires w/female cable shoe connectors.

Cable shoe connector example.

I'd like to attach the timer directly to a circuit board of my own design. What type of connector do I solder onto the circuit board? Should I just take any female connector, strip off the plastic coating, and solder it onto the board...or is there a more specific product for this?


texts:
I came across the ICL7673 IC used for a battery backup system but I could not understand exactly what is the role of the R2 and R4 resistors in the circuit below (marked with red):

So my question is: what role does the R2 and R4 resistors have?
When Vp > Vs , P- is high and S- is low and when Vp < Vs, P- is low and S- is high. Since we have the R1 and R3 resistors to bias the base of the PNP transistors, why do we need the R2 and R4 resistors? If somebody could explain this to me (in detail) I would greatly appreciate it.


texts: How to modify stranded wire for use in protoboards?

texts:
I decided to start working with hobby electronics, but I'm having a problem finding a local source of solid wires. As far as I know solid wires are often recommended for use with protoboards because inner wires of stranded wire can get jammed inside protoboards wire holding mechanism.

I'm looking for tips on how to modify stranded wires to work with protoboards.

The obvious solution which comes to my mind is to use solder on the exposed part of the wire and make it solid.

Any other ideas?


texts: Are solenoids/inductors dangerous to have exposed?

texts:
An inductor doubtfully will be in a position to be of harm, however a solenoid with 1A+ running through it (and of course a lot of it stored in the magnetic field) can certainly harm the circuit, if not somebody touching it at one point.

From what I would imagine, the stored current will be converted back from magnetic flux and then be sent in to the circuit again, however, is there any harm in somebody happening to touch a (50mA->1A) solenoid when continuously on? When the circuit is accidentally ungrounded (not 100% my worry) or turned off?

The input voltage should always (hopefully) be under nine volts, and I will be using it as a small electromagnet maybe for experimenting, however if the release of current causes a large potential that is one of the concerns although I do have quite a lack of understanding.


texts: What does "open drain when programmed for the wait function" mean (in micro controller spec language)?

texts:
So I am reading the Zilog Product specification for the Z8440/1/2/4, Z84C40/1/2/3/4  serial input/output controller (here it is
http://www.zilog.com/docs/z80/ps0183.pdf).

And there is one sentence I dont understand the meaning of:

Here is the schematic with the leg marked:

I can understand, for example, TxDA, TxDB. Transmit Data (outputs, active High) which to me means that the pin will have voltage (it will be pulled high), when the controller will starts sending data to the output channel.

But what does it mean by "open drain when programmed for Wait function"? What is this drain and how to open it?


texts:
I'm using an ATtiny85 to generate a PWM output (using Timer0 in OCR mode), and this PWM output is being switched on and off at regular intervals. I am finding that when switching on the PWM output, there is a delay before it actually starts outputting.

Look at the screenshot below, the green line shows the state I am putting the PWM into (either on or off via TCCR1) and yet there is a delay of what looks like one full cycle before it starts. I've tried also resetting TCNT0 to 0, but this had no effect.

(Timebase is 20 µs.)

SET(DDRB, PB1);
SET(DDRB, PB2);

// Set up PWM for 460 kHz with 8 MHz clock
TCCR1 = (1<<PWM1A) | (1<<COM1A1) | (1<<COM1A0) | (1<<CS10); // Prescaler = none;
GTCCR = (1<<FOC1A);
OCR1A = 9; // 460.750 kHz
OCR1C = 18;

#define BIT_DELAY ((1000000/38400))

while(1) {
    SET(TCCR1, PWM1A);
    SET(PORTB, PB2);
    _delay_us(BIT_DELAY);
    CLR(TCCR1, PWM1A);
    CLR(PORTB, PB2);
    _delay_us(BIT_DELAY);
}


texts: Help Identify a Connector Type for Beats Solo 2

texts: I have a broken Beats Solo 2 headphone where the only broken/missing component is a connector that I cannot identify.  I've obtained a picture of the headphone from a tear-down of the headphones and circled the connector in gray.


texts: How can I make Bluetooth (2.4 GHz) reception area narrow and controllable?

texts:
There are some Bluetooth modules available on the market, like the cheap HC-05 for 3 or 4 USD delivered.

This one mentioned has an internal PCB antenna which I guess has a toroid-like radiation pattern (omnidirectional):

However I need this module to be receivable in the narrow area only. Like 5-10 square meters area between the module and the ground.

What can I do to make this possible?

Put some metal case around?
Cut off the internal antenna, and connect an external directional antenna?

Any other thoughts?


texts:
I'm trying to build an electric field receiver to detect VLF waves so my bandwidth will essentially operate within the range of 1 kHz to 100 kHz. I will have a short whip antenna(1-2 m long) as my antenna and I am trying to figure out the design for the preamplifier.

I'm a beginner at this so I may be approaching this wrong so I wanted to get some feedback over my design. I don't have a detailed circuit diagram yet but as a rough concept, I'm thinking of using a differential JFET common drain(source follower) as the input stage(which will have high input impedance and low output impedance). This stage will have really low noise and low gain since this stage affects the noise figure of the whole amplifier the most.

Then, for the gain stage, I am thinking of using a differential BJT common base pair which will be DC-coupled. This stage will bring the most gain and again needs to be low noise as well.

For the output stage, I am thinking of using a voltage follower op-amp with a step-down transformer.(I am not sure of this stage. Maybe using an emitter follower is a better idea?)

If I can optimize this design, would it work pretty well for my case in terms of gain, noise and bandwidth? Also would this be a better design over a conventional JFET input op-amp/instrumentation amplifier?


texts: Is it possible to make a coil-less simple Shortwave Receiver

texts:
I am really a newbie here in Electronics and I'm into it as a hobby/passtime.
I was going through this simple coil-less Shortwave Transmitter circuit on a blog.

Q1 – BC548, X1 – 10.7 MHz ceramic resonator, 3 terminal, C1 – 10 nF, C2 – 100 nF, C3 – 100 pF, R1 – 10 kOhm, R2 – 150 kOhm, R3 – 1 kOhm

My questions are:

Does circuits like this work? I want to know how this circuit oscillates at a shortwave frequency without LC Tanks. Is it entirely done by the ceramic resonator?
Can I create a similar circuit to receive Shortwave audio signal, which won't use a old-days coil and ferrite rod? If someone could help me with a simple circuit diagram for a shortwave radio receiver which uses such ceramic resonator I will be grateful. I couldn't find it on the web.


texts: What is the voltage potential of ground during a short

texts: During a short, is it possible for the voltage potential of the ground to change? Say for example, we short a 9V battery, how does the ground stay at 0V and not become 9V?


texts: Proper phototransistor for detection of small object

texts:
I am attempting to detect a falling objects 6mm in diameter, falling every 160ms.  The object to be detected will be confinined to a black tube, void of light, 18mm wide x 35mm long, my plan is to mount a IR led on one of the 18mm wide faces and place a detector on the opposing face. My question is what is the most suitable sensors to pick up the IR signal.

I have tried using what I believe to be photodiodes, with minimal success.  If the object falls directly in the line of sight I can see a difference in voltage on my Arduino.  I'm not sure if the response of the diode is too slow or the window of detection is too small.

I have considered photocell, but understand that they are too slow.

I believe that a photoresistor is what i should be using, but am unsure if I can have a large enough "window" to detect the falling object if it doesn't fall directly in the line of sight of the emitter and receiver.

Is a photoresistor the best choice for my application?

I am very new to electronics and have no formal training.


texts: How to power PSOC 5LP from boost converter

texts:
I have the CY8CKIT-050 PSOC 5LP development kit, and I have read that I can power my chip though boost converter (Page 16, last line), but I don't find any place where get information about how to configure boost converter to power the chip. I tried just to disconnect the usb supply but as I expected, the boost converter didn't power the PSOC.

Incidentally, I don't have any components connected to the PSOC, just the power supply to the boost converter and the USB connected to my laptop.

I hope someone can help me. Thank you for your answers.


texts: Can I order PCB/chip manufacture from provided LOTOS specification?

texts:
Is there a way to automatically deduct PCB and/or chip design from formal problem specification of a problem (task) which supposed to be solved on a PCB/chip?

I'm currently implementing solution with OpenCL to be run on GPGPU in conjunction with CPU. To decide which part of an algorithm must be run on CPU and which on GPU I had to manually calculate speed of sorting on CPU and GPU and divide by speed of GPU <-> CPU communication.

All sorts of such problems, I think, can be solved automatically by applying of problem description upon hardware specification.
Googling all of these brought me to pretty complicated and abstract topic of formal methods where LOTOS seems to be one of them.
I learned a little bit of electronics and know that in-circuit electronic processes and components are very well mathematically defined and deterministic, so automatic PCB/chip layout must be able to be deducted from problem description. But I can't find any working tools/libs which can already do it.

I wonder if there is already working solution of how to do it?

P.S. Problem I'm trying to solve is about ~50 lines of somewhat close-to-machine specification, but I had to write already ~5000 OpenCL/C++ code to run the solution upon a device which at first glance is at least 10000(!) times less effective (speed*power-wise) than analog ASIC would be. I feel like I wanna cry :(

Somewhat close task specification of my problem in C-like pseudocode:

[declarations]
struct A { float Temp; float Value };
A Mem[ MEM_COUNT ];
A Cur[ CUR_COUNT ];

[process #1]
A S;
S.Value = getCurrentInputValue( attachedCamera/Mic/textFile/etc. );
S.Temp = 1;
Cur[ end ] = S;
for each C in Cur:
    C.Temp += 1 - mod( C.Value - S.Value ) / C.Value;
approximately sort Cur by Temp;

[process #2]
A C = Cur[ 0 ];
for each M in Mem:
    float sum = 0;
    //farthest set is defined as each (MEM_COUNT / FARTHEST_COUNT)'th A starting from M
    for each farthest of M:
        sum += farthest.Value / FARTHEST_COUNT;
    M.Temp -= mod( sum - M.Value );

[process #3]
A M = find M with the most Temp from Mem[];
outputValueToAttachedPin( M.Value );

And I would like to tweak MEM_COUNT, CUR_COUNT and FARTHEST_COUNT to see the resulting speed/price/power/etc. As I know, today's CPUs designed so that a program needs to do ~300 operations per every memory access, but in algorithm above it goes up to FARTHEST_COUNT accesses per operation. So, ASIC would be 300*FARTHEST_COUNT times more efficient?


texts: 2 momentary button into 1 persistence output with clk pulse

texts:
I'm making a binary input button pair with one or "1" and the other for "0" and load this input into a shift register so I need to have from these 2 buttons a persistent line for data either "1" or "0" as well as a clock signal to load the register.
The clk pulse is simple since all I need is to debounce both the switches and wire them both directly to the clk pin, the pulse will be generated when the button are pressed (or released)
I'm at a loss as to how to have either a persistent "0" or "1" so when the pulse from the clk comes data can be loaded into the register.
I understand that you need a mux and/or a flip flop to achieve this but I can't figure out the wiring for the life of me.
Thank you.


texts: Does the Epson RX8900 real time clock count the year "00" as a leap year?

texts:
The datasheets ambiguously say...

  A leap year is set whenever the year value is a multiple of four (such as 04, 08, 12, 88, 92, or 96).

Is zero a multiple of four? This is more of a philosophical question than a specification. The shown series starts at 4 and ends with 96, strongly hinting that the good folks at Seiko do not think that zero is a multiple of four.

Turns out to be a critical fact if you are trying to measure timespans - if you pick wrong then any date after Mar 1, 00 may be off by a day!


texts:
I need to read 4 full-bridge load cells about 10 times per second. Are there any drawbacks of connecting two cells to A and B channels of HX711 and alternating reading between them?

I understand that I will loose the precision (because I'd have to set the data rate to 80SPS) and resolution (because of lower gain on channel B). However what I am concerned about, is if parallel connection of two cells to excitation voltage will introduce cross-talk that will further affect the results.

UPDATE:

The 500kg load cells connected to HX711 breakout boards with 1.5m shielded cables. The breakout boards are mounted on custom STM32 controller PCB for prototyping. In the end I am planning on integrating recommended application schematics from HX711 datasheet directly into controller board.

The reason I am asking the question instead of simply doing some testing is that Sparkfun breakouts have additional filtering in channel A sensing lines and a lot of filtering/bypassing on avdd/vcc lines, that I was not planning on incorporating into final product.

I simply want to know if I need 4 of these on the board or can get by with only 2, before I begin routing and ordering the PCBs.


texts:
I have a question concerning this shunt ohmmeter:

If we only want to use the \$R \times 1\$ gauge, we have the following circuit:

I want to know what indication would appear on the ohmmeter if I put a resistor \${R}_{x} = 24 \Omega\$

So far, I've found that I can find \$I_m\$ using the following equation:

\$I_m=\frac{15}{16995 {R}_{x} + 400580}\$

Which means that \$I_m = 18.72\mu A \approx \frac{FSD}{2}\$.

My professor has said that the scale is arithmetic and has a maximum value of \$10 \Omega\$, so that the indication is \$R = 5 \Omega\$.

Why this value is different from \$24 \Omega\$ ? Is it because the scale of the ohmmeter is not good ?


texts: Input resistor to BJT base > ground resistor, why?

texts:
Thank you for your time.

I'm new to electronics and so this question might, to you, call for an evident answer. Nevertheless, I can't seem to find that answer.

I've stumbled upon a schematic for a BJT-only, 4-bit computer. When I look at the XOR gate that's part of the first full-adder (only shown here), I see that R5, which connects the Q4 base input to ground is 10 times smaller than R6. Won't that sink most of the current? Because the base doesn't need much to saturate, I understand that it could still be enough; but I wonder: why is this configuration desired?

(You can see the same configuration on R8 and R13)

Thanks again!


texts: STM32 PWM only works correctly when I leave in two unused variables: StartUpCounter and HSEStatus

texts:
I'm using the stm32f3discovery board to try and generate the signal for a ws2812 light strip.

I've got src/system_stm32f30x.c, which I copied from the StdPeriph examples.  I'm currently using the internal HSI, and the clock speed is 48MHz.

I'm using gcc-arm-none-eabi-4_8-2014q3 to compile.

If I leave src/system_stm32f30x.c as is, I get compiler warnings about unused variables, HSEStatus, and StartUpCounter, but my program works correctly.  If I rename the variables to test1 and test2, it still works as expected, so it appears that it doesn't matter what the variables are named, it just matters that they are taking up memory (I guess).

However, if I comment these variables in order to get rid of the warning, my program no longer works correctly.  The first pulse of the PWM signal is either grossly too short, or way to long.  It causes the first LED on my strip to flash erratically (though the rest of the LEDs are fine).

My code is here: https://github.com/synic/neoclock/tree/stm32f303

What could it be?


texts: 7 segment display flickering when using switching power supply

texts:
I have two 4 digit seven segment displays that work perfectly fine when I use the LM7805 however, when I use the switching power supply, some segments sometimes flicker on their own.
Can anyone please explain to me why this happens and how can I fix it and still use the switching power supply, I can't really use the LM7805 because of the heat issue.


texts: is sound produced by varying current or voltage?

texts: In a sound system (computer, stereo, CD, etc.) is the (just) current or voltage (and therefor current) modulated to create the output to the speakers?  If the answer is both, what are some examples of each?


texts: using an AduC841 microcontroller. memory read shows pointer not object pointed to

texts:
I am using an AduC841 microcontroller programed using assembly language(8051). when using MOVX commands to read/write from internal XRAM to DAC,my oscilloscope shows the value of the DTPR rather than the object  pointed to. How do I out put from memory? the command I'm using is MOVX A,@DPTR; and then MOV DAC0L,A;
(I had tried to implement a scope in normal mode using XY of a scope as display, for a school project, but whenever a one time trigger event occurred it showed a sawtooth wave, so I devised a test program which showed that I was receiving the DPTR value)


texts: Making subwoofer for car, without amplifier

texts:
So, I have these two things and I want to achive a good subwoofer for my car: an 5.1 home theater system with a 20-30w 4ohm subwoofer and a radio player in my car with 4x45w 4ohm output for speakers.
As far, I cleaned everything from the subwoofer(the amplifier for the 5.1) and now its just the speaker part with the 2pin cable. A tied with one of the chanels from the radio player, and its working, but.. The subwoofer gots the main signal and isn't sounds like before.
I mean its okay, but I want to cut off the high frequencies, because I hear like he wants to be a normal speaker. Any low cost ideas? I was thinking about a low-pass filter, but as far as I know I can't make it this way. Tell my if I'm wrong.
(It may sounds dumb what I ask, but I want a DIY, cheap method. This area its totally new for me.)


texts: How does the discharge rate of the battery pack in an electric vehicle vary from 1C to 4C for example when the vehicle accelerates? It's the same electric motor and the same battery. How does the electric motor vary it's load on the battery?


texts: I'm looking for a small and simple 1-2 second power-on delay circuit which would power the bluetooth module (20mA @ 3.6V). I have tried to achieve this using 2n3904 transistor, few resistors and capacitor, but unsuccessfully. Various schematics I found on the internet doesn't seem to work as expected. Any help would be greatly appreciated.


texts:
For a recent examn, i was asked to create a counter, that counted backwards from 15-1 then starting over from 15, in odd numbers. I did so with a T flipflop, and the following question was for me to implement the same thing, with a D flipflop.
In my answer i just added an xor gate to the input, and made the flipflop to a D one.


texts:
I'm currently building an Arduino based LED driver using a set of three CD4094's, I'm slightly unsure of an error I'm getting with my Eagle schematic. The error message reads: 'No SUPPLY for implicit POWER pin ICP3 VSS' - however I can't see which pin I'm supposed to attach VSS to? Here's my pinout:

Is this just an erroneous message or have I made a mistake? When I've seen schematics with this IC used before, they have used the same pin mapping as I've used...


texts: I've been doing some research on switched reluctance motors, and the papers are always talking about driving them with inverters. Why would you use an inverter as opposed to just using a single switching element to turn the coils on and off?


texts: What is the point of these components on the schematic? (Digispark ATtiny85)

texts:
The above schematic is for the Digispark ATtiny85 development board.

I am still fairly new to electronics, however I understand what all these components' functions are. I am just not sure why it is used in this way...

In the schematic I circled the components in question:

What is the point of the two capacitors (C1 and C2) from 5V to GND?
Why is the diode (D3) there? Should it not be flipped the other way around?
What is the purpose of the two zener diodes (D1 and D2)?


texts:
i'm trying to control keysight instrument. And i constructed a block diagram in Labview. It works at first, but at second time it won't even respond to *IDN? Command. Visa read block gives timeout error.

I tried restarting my computer, and i tried same block diagram , it works. But at second time, it gives same timeout error in visa read block.

I looked at Keysight instrument's screen. It does not show my sent scpi command on scpi command log, that's why visa read block gives timeout error. But i can't understand why i cannot work same block diagram twice Via Labview.

What do you think the problem is?

PS: When i try Keysight Connectoin Expert's Interactive IO, it works, so i think there's a problem on the Labview on my computer.


texts: What is the definition and purpose of a pre-amplifier?

texts:
I find in many places mentions of pre-amplifiers being used to boost audio signals prior to feeding to a power amplifier.

Wikipedia's article on pre-amps gives some hints at their usage, but it doesn't really explain why it would be necessary to have two amplifiers in series rather than a single one with greater gain.

If a pre-amp is just a power amp with a smaller gain, what's the point, and why the distinction between the two kinds? Is the distinction in function, or simply purpose?


texts: Push-Button Voltage Spike (not debouncing)

texts:
I have a circuit which reads push-button presses. If it is pressed, it turns on the door by rotating motor. In this system, safety and stability are keys.

I added r/c filter to debounce button and cables are also shielded. Pull-up resistors also exist but there is a problem which is voltage spike.

Let me explain with some examples, when i run a drill next to cables, it reads randomly button presses or when i shake circuit roughly, it randomly reads button presses.
It happens rarely but the system should be stable and does correctly for a long time such as months, years, so these random presses are not acceptable.

To solve this, I added a relay and connected it to power with a push button. When push button pressed current flows to relay and switch it. I read button presses from relay. It works stable. But I am not sure that i am doing right or whether there is a better way to prevent those spikes.

If there are any other viable solutions to this problem, i would like to appreciate to hear.

(Push button wires are about ~50cm)

Kicad project files
Kicad Project Files

Circuit http://ozmach.com/public/board-v2.zip
  1: http://ozmach.com/img/schematic.png


texts: Is 555 timer good to generate 20MHz clock?

texts: I am looking for a way to generate 10 to 20MHz TTL-compatible clock signal. I used something like microchip unit to produce clock signal before in school but I didn't use any other way to generate clock pulses. Someone suggests to use 555 timer but I one of the handbook I have told that 555 timer won't support clock frequency as high as 20MHz. Is that true? I need a pretty stable clock signal which will be run for more than 60 hours continuously once it is on. Any other suggestions?


texts: Help me to identify this crystal oscillator module

texts: Please help me to identify the manufacturer of this crystal oscillator module so that I can search for its datasheet.


texts:
I have a requirement of DC DC power supply where the input voltage is -48VDC and output voltage : +5V and -5V with output current 4A and 3A. Is it correct to use a DC DC power supply of more than 35W and give the inputs as inverted polarity?

Thanking in advance


texts: Random signal lost or extreme weak signal with remote controller on ISM frequency (433Mhz)

texts:
There is a task given to me that I have to investigate a problematic RF remote controller against its weakness and make a suggestion report how it can be improved.
This RF remote controller is used with two hands like PS console remotes. While it is functioning normally, in some cases, signal is not correctly or completely received by the receiver.
Edit: The receiver is under the bed controlling motors.

Here are my findings, considerations and modifications;

1. Hands or human body on the remote controller are causing attenuation over the transmitted signals significantly at some directional orientation. (Observed with RF spectrum analyzer in dBm). At those moments, sometimes data is not properly received by the receiver but not always, unpredictable.

2. Antenna is on the 4-layers PCB. This anteanna is working OK when there is no obstacle. See image.

3. RF circuitry and micro-controller are all together and no shielding on the RF side. See image.

4. I have cut out on-board antenna and added a smd female RF connector. This way I experimented these steps;
a. with teflon brown cable and connected a 17.3 cm wire.
Antenna is inside the box: More or less same dBm measured as the on-board one. Data lost is not checked yet since it is not always the case.
b. with teflon brown cable and connected a 433Mhz whip antenna. This is shorter, most likely it has a spiral version of 17.3 cm antenna inside.
Antenna is outside the box: 30% more dBm measured than the on-board antenna does. And most importantly, hands and human body factors are quite less effective over the signals.

5. My point of view, the RF circuit part standalone is looking OK to me in terms of proper matching and harmonic suppression.

So, After those info and the image, what mistakes are you seeing (if there are)?
How can this RF circuitry be made more effective by all the RF design technics considered?

I hope that I could explain what I am up to.


texts: ipod dock upgrade for inmotion speakers unit

texts: I have an inmotion speaker set with embedded ipod dock circa 2006. I love it and it sounds great. But the dock does not work with the newer model ipods / iphone etc. I'd like to try my hand at hacking it to upgrade the dock. Any thoughts on how to do this? Seems to me that somehow I could replace the old connector with the part of the new one.


texts: Why does this dimmer switch have reduced wattage capability for LED / CFL bulbs?

texts:
The Lutron "Maestro C•L" dimmer has different wattage ratings depending on the type(s) of bulbs being controlled. Its an electronic dimmer.

Specifically, when 100% incandescent or halogen it can handle 600 W, but when 100% LED or CFL only 150 W, with a gradual variation between these extremes for mixed bulb types.

Info from the specification sheet:

(The wattage capability also varies based on the # of "sides removed" though I can't see in the docs what that means.)

Source: http://www.lutron.com/TechnicalDocumentLibrary/369613a.pdf

What is the reason for the degraded wattage capability when running LED bulbs?

And is this variation in wattage capability typical of this sort of dimmer?


texts: PIC18F25k50 - 10-bit PWM resolution with 8-bit timer?

texts:
Im messing around with PIC18F25k50 standard mode PWM.

I found something weird. Datasheet says, that PWM is 10-bit, and timer is 8-bit.

How that can be?

Is that datasheet is wrong, or my english is too bad to understand that correctly?

What is the point of 10-bit PWM with 8-bit timer?


texts: How to wire a digital LED voltmeter in line with an illuminated rocker switch so the switch light is on and the meter displays the actual voltage

texts: 12v power supply to put output signal on a 7 way trailor connecter.How to wire the LED voltmeter in series with an illuminated rocker switch,so when the switch is turned on,and the light is lit,the volt meter shows read out of the actual measured voltage.


texts: How to calculate the collector resistor of this emitter circuit?

texts:
My supply voltage is +10 V, collector current at my bias point is 5 mA, base current is 28.8 uA, amplification is 173.3

I already calculated the base resistor to \$R_1=\frac{V_{CC}-V_{BE}}{I_b}\$ and it seems to be right.

These are the correct values according to the solution:

\$R_1=322\text{ kΩ}\$
\$R_2=2140\text{ Ω}\$

I cant seem to find out how to get R2.


texts: I removed a little motor from my laptop fan and it won't run using a 9V battery

texts:
I realize this is may be a noob question so please point me to the right place to ask it if this isn't so. Anyway, I'm trying to build a little magnetic blender using a spare laptop fan. I tried plugging the red and black wires (and every other possible combination) into a 9V battery but it didn't run at all. So I broke the whole thing apart and ended up with the motor inside:

When I plug the + and - ports from my battery to the metal things in the motor (A and B in the picture), it turns about half turn and then it stops, and when I switch the poles it runs a little more, and so on, always on the same direction. So I guess the poles need to switch intermittently, which I understand means I need AC instead of DC? Is there a way to easily have this motor work using a battery or power from my outlet using simple tools? I understand home current is AC, but I'd need a way to lower the voltage while keeping it AC, and I believe phone chargers all output DC.


texts: Voltage regulator for ultra low power device

texts: I am currently designing a battery powered IoT device, which maximum voltage is 3.3V. When it comes to battery choice, the CR2032 (3V) is totally fine, but its capacity is only 250mAh. How can I power my circuit from single 18650 Li-ion cell? The problem is that this battery can achieve 4.2V when fully charged. What would be the basic circuit and which voltage regulator to choose? I currently ordered SPX3819. I am afraid it will discharge my battery faster then NRF24l01 and ATtiny84 attached to it.


texts: Is meaning of rated voltage not always same?

texts: Well, I'm stuck in choosing DC barrel jack which will supply power for my circuit board from 12V 1.5A AC/DC adapter. Its spec says voltage rating is 18V and current rating is 1.5A. Well.. I know that for IC devices I should supply voltage near the voltage rating to guarantee their proper operations. How about these type of parts like connector, socket, etc... ? Can I just go on with this barrel jack with 12V 1.5A supply?


texts: Need help identifing the power rating for this resistor

texts: I have this wire-wound power resistor that appears to be either ceramic or porcelain in construction with a soft brown plastic or vinyl like coating. I want to find out its power rating. My meter shows about 5.2 ohms. A Google search for 160DR5WL returns nothing.


texts: I dont know how to amplify a signal of 25mV to 5V amplitud signal ((frequency of audio input cell phone)). I have this circuit so far:


texts: Should there be any PCB ground plane under a 16 MHz oscillator?

texts:
For a 2-layer PCB,
should there be a ground plane under a 16 MHz oscillator?
From this PDF document,
http://www.nxp.com/assets/documents/data/en/application-notes/AN2500.pdf,
it shows the following figure,

which suggests not to have any ground plane under the oscillator components.

whereas a response from here (When to use ground plane cutouts?)
says:

  In fact, it is highly recommended to run your high-speed signals
  directly overtop of an unbroken ground plane;

So my questions are:

Would the lines for a 16 MHz oscillator be considered
"high-speed"?
Would it be correct to not have any ground or power planes under
16 MHz oscillator lines + related components?


texts: Capacitor selection for filtering of low level signal

texts:
I am currently dealing with low level signal(voltages in milli-volt from the sensors) for the first time. I was advised to use filtering circuit moreover RC filtering which I have already implemented. But as I am new to low level signal filtering, I do not have sufficient knowledge on capacitor selection.

For the filtering purpose, should I use normal ceramic capacitor or a capacitor something like metalized polyester capacitor? What capacitors are best for low level signal filtering?

Concern is on PCB size,i.e if I use ceramic capacitors (0805,X5R,0.1uF) pcb size would decrease by significant amount but if I use metalized polyster film capacitor like this it would require more PCB space.
How bad a capacitor selecton would affect for the needs of such low level signal filtering?


texts: How to configure the FlexMemory of NXP Kinetis MKE18F to be used as an EEPROM to store data on System power OFF?

texts:
I was trying to configure the Flash module of NXP MKE18F512VLL16 MCU to be used as an EEPROM.
I followed the attached application note from NXP(AN5338) "How to use FlexMemory as D-Flash and EEPROM in KE1xF" along with the datasheet as reference.
I encountered a question when I was studying the FTFE flash module. Here in MKE1x, Flash Common Command Object Registers (FTFE_FCCOBn) is used to write commands to be executed by the memory controller. The register structure is as follows, (command - Flash Address - Data Bytes).
Here according to the datasheet, the register will take only 24 bits of data for Flash Address argument while the MCU has a 32 bit addressing scheme. This confused me. How do I write a command to erase/program a specific region with a 32 bit address while my register will allow me to write only 24 bits?
Keeping this question aside, I tried to study the FlexNVM EEPROM example from NXP for the MKE18 controller, but I was unable to extract relevant read and write functions by solving the dependencies from the company provided SDK.
I'm using Keil MDK5 IDE for development. No RTOS - bare metal project.
The following is my code which I tried to write into the EEPROM and read it back.
#include "MKE18F16.h"                   // Device header
uint32_t read_data = 0;
uint32_t targetadd = 0;

void FlashInit(void){
    PCC->PCC_FLASH |= PCC_PCC_FLASH_CGC_MASK;   /* Enable clock for flash */
    FTFE->FSTAT = 0x30;     /* Clear error flags */
    FTFE->FCCOB0 = 0x81;    /* Set FlexRam function to EEPROM */
    FTFE->FCCOB1 = 0x00;
    FTFE->FSTAT = 0x80;     /* Launch Flash Command */
    while (!(FTFE->FSTAT & FTFE_FSTAT_CCIF_MASK)); /* Wait untill command is completed */
}

void FlashEraseSector(uint32_t TargetAddress){
    FTFE->FSTAT  = 0x30; /* Clear Error Flags*/
    FTFE->FCCOB0 = 0x09; /* Flash Erase Sector Command */
    FTFE->FCCOB1 = TargetAddress>>16;
    FTFE->FCCOB2 = TargetAddress>>8;
    FTFE->FCCOB3 = TargetAddress;

    FTFE->FSTAT = 0x80; /* Launch Command */
    while (!(FTFE->FSTAT & FTFE_FSTAT_CCIF_MASK)); /* Wait till command is completed */

}

void FlashProgram(uint32_t TargetAddress, uint32_t Data){
    FTFE->FSTAT  = 0xF0; /* Clear Error Flags */
    FTFE->FCCOB0 = 0x0B; /* Flash Program Section Command */
    FTFE->FCCOB1 = TargetAddress>>16;
    FTFE->FCCOB2 = TargetAddress>>8;
    FTFE->FCCOB3 = TargetAddress;
    FTFE->FCCOB4 = Data>>24;
    FTFE->FCCOB5 = Data>>16;
    FTFE->FCCOB6 = Data>>8;
    FTFE->FCCOB7 = Data;

    FTFE->FSTAT = 0x80; /* Launch Command */
    while (!(FTFE->FSTAT & FTFE_FSTAT_CCIF_MASK)); /* Wait till command is completed */
}

void FlashRead(void){
    uint32_t* pnt    = (uint32_t*)targetadd;

    read_data   = *pnt;
}
int main(void){
    SystemInit();
    FlashInit();
    targetadd = 0x10000000; /*FlexRAM start address */
    FlashEraseSector(targetadd);
    FlashProgram(targetadd, 0x10);
    FlashRead();
    while(1){

    }
}

With these functions, I was not able to read back the data which I've written. Pardon me for my mistakes as a beginner.
Attached Files:

MCU Datasheet. - https://www.nxp.com/docs/en/reference-manual/KE1xFP100M168SF0RM.pdf
EEPROM Application Note. - https://www.nxp.com/docs/en/application-note/AN5338.pdf


texts:
I see transformer specs listed as 360-0-360 for a secondary of a power transformer. I understand that this means there is a center tap, and with a full wave rectifier this comes out to VRMS * 1.4142 = 360VAC * 1.4142 = ~509 VDC (assuming smoothing caps etc, beyond the scope here)

But if you remove that center tap, then you could say the transformer is 360-360, or 0-700, correct? So if you then used a full wave bridge rectifier on 720VAC, you would have 720VAC * 1.4142 = ~1018 VDC.

Obviously I'm missing something crucial here about how transformer specs are defined. I certainly don't want to be off by a factor of 2 when I'm getting my transformer manufactured.


texts:
I’m supposed to build a buffer circuit for pc oscilloscope using the sound card of the pc and a software “zelscope”; however there’re limitations:

Not possible to display DC because there’s a DC blocking capacitor in the sound card.
Low frequencies range only (20kHz).

Any idea about a buffer circuit that solves these limitations?


texts:
I'm working on a wearable project that is really space constrained.  Originally, I had planned to use a Li-Ion battery, but I opted out of it because the person wearing it won't be able to take the wearable off in case there is a catastrophic battery failure.

I would use a triple-A battery, but those are too large.

What battery can I find that is smaller than a triple-A battery, but still fits the following constraints:

Safter than Li-Ion
Smaller and lighter than triple-A
Nominal voltage of 3.0V (I would be willing to use 2 1.5V cells if they are small enough)
Charge capacity >= ~50mAh
Capable of delivering up to 300mA in very short bursts for rf transmission (about 30 milliseconds).  Otherwise the "resting" current consumption of the system will be on the order of 10μA.

I've found plenty of small batteries that satisfy one or 2 of these requirements above, but I can't seem to find one that fits all 5 except the 110mAh li-ion that I linked above.


texts:
I need to build a small circuit to control some relays where I need to power a Raspberry Pi Zero from mains power using the GPIO pins.
I saw this module: Mean Well IRM-05-5 5VDC 1A 5W.
Is this module suited for the job? Do I need to add more elements to do filtering/regulation or I can just connect the mains directly to AC input and then DC out to Raspberry Pi GPIO?
Are there more better modules or more "professional"?
Thanks.


texts: What is the best way to turn the knob on a lamp automatically?

texts:
I've been bored during quarantine and decided to build my very first circuit that wasn't school-related. I want to make my lamp remote-control, and my initial thought is that the best way to do this is have a servo motor turn my lamp's on/off knob enough to toggle the light. I can't seem to find anything on Google that would help me use the servo motor to "grip" the knob, though, and that makes me think my approach of using a servo motor is the wrong idea.

What would you guys suggest? My thoughts went to servo motor since, like my lamp knob, it turns rotationally. I'm quite the beginner though so there's a whole world of components I could be missing that I'm just not quite sure how to search for.

Thanks a bunch!

After posting this I've done a little more searching and have actually found grippers. So I now have found something that could grip my lamp's knob, but they don't seem to have a way to rotate on their own and it doesn't look like they're made to be attached to a servo motor. I feel like I'm getting warmer, though.

Here is an image of the lamp's knob, my servo motor, and my step motor:


texts:
Basically we're building a simple setup with an Arduino board and some motors. The Arduino with motor shield will control several servo motors and DC motors, and possibly talk to a few sensors. This seems to work.

But rather than hook up an XBee, or wifi or something complicated, we'd like to just throw a moto droid into the payload. This would give us A) long range communication through the internet B) a camera we could control via the internet C) realtime video from the droid's camera.

So our question is: the droid has a micro USB port on the side. What's the easiest way to plug that into an arduino (or go-between) and read/write data? I've seen a page where a guy used bluetooth, but I was hoping for a wired connection.


texts: What is the difference between a PUT and a normal transistor?

texts: What is the difference between a Programmable Unijunction Transistor and a normal transistor? I am reading the book Make:Electronics and it says I need one of those. Can somebody explain to me in somewhat non-tech terms what it is?


texts: Why would this (simple) over voltage protection circuit raise the output voltage?

texts:
as a beginner I have recreated this circuit:

I found it in this guide, and I was hoping it would work as intended but instead it gave me some weird results. I connected power to the circuit and probed the input voltage (2.5V), and then subsequently I probed for the output voltage. It gave back readings of many different voltages, but all higher than the input (3.6V-4.0V, rarely but sometimes higher). I have no idea why this would happen (no inductors or anything like that).

If you look in the guide, it lists the specific components; I had to subsitute a few:

I used the S8550 instead of the FMMT718
I used a 2.7V zener diode similar to this, instead of the 1N4740A

I think perhaps I should have chosen a transistor that had a lower saturation voltage (like the guide says), but besides that I don't see these components doing any harm.

So if anyone can help me troubleshoot this it would be much appreciated.

P.S.

Bonus Question:

I understand the principle behind the circuit and nearly everything seemed to make sense to me. The only thing I didn't get is why R4 is there. Is it even needed? I think maybe the author of the guide accidentally kept it in from the first circuit he drew, or maybe it has a purpose and function I cannot understand. Thanks all in advanced!


texts: Extend flat cable between LCD panel and driver board

texts:
Given a setup similar to this: https://www.adafruit.com/products/2395
The panel itself is nicely thin, but the driver board takes up some space. So I need to put it somewhere separate from the display. Is there a way of extending those FFC cables to about 1-2 meters? Preferably using a non flat cable.


texts: Sampling frequency range of an discrete signal

texts: Is it possible to detect each and every frequency above the nyquist frequency? Or this can be also discrete Thank you.


texts: Need help how to disconnect this (pictured) connector inside a tablet computer

texts:
I need to remove and replace the battery inside a tablet computer (a Nuvision TM800W560L, circa 2015-2016).

Between me and the battery lies a flat, flexible PC board style (ribbon?) cable terminated in a (tiny, delicate) connector (the end pictured is a bit more accessible.) A photo is attached/below.

I certainly do not want to damage the connector during cable removal and re-insertion!

What is this type of connector called, and how should it (properly) be disengaged from the cable (so it can be re-engaged later)?

Thank you for any advice!


texts: What type of transistor generally has the lowest flicker noise?

texts: How do BJT vs JFET vs HBT compare in terms of \$1/f\$ noise amplitude and corner freqency? I know these transistor types are very different, used for different frequencies and powers, and each have many different variations all with different flicker noise, but on average is one type better than another?


texts: Diodes question (I Got the answer but I just need more clarification)

texts:
Problem : finding I2 and V

at the end of solving I got I2 = 0
by making D1 open and D2 is short circuit.

I just don't understand how the answer for V at the end is -1.7

I tried open D1 and therefore I2 = 0

then I thought it is all together now so I1 = I3 =( 5 - (-5))/15 =  0.666666666mA

then I got lost on how to find V, since I read the solution to be V = -1.7

I tried doing the .6666 * 5 or .66666 * 10 which didn't get me toward the answer

Any explanation that can walk me through would be much appreciated


texts: Drive a magnetron with low power via a CCFL backlight driver

texts:
[EDIT] My real question here is: can a magnetron from a microwave oven be used to output low power microwaves? If so, how can I achieve this? If not, what is a source for low power microwaves? In this context, low power means that I don't intend to output microwaves that are dangerous to a human being.
[/EDIT]

Is it feasible/reasonable to drive a microwave oven magnetron from a CCFL backlight driver? From what I've seen, the voltage produced by the CCFL driver should be in the ballpark what a magnetron accepts.
I want to use the radiation for measurements, so I don't need the high power a megnetron would typically produce and a lower power rating makes this feel much safer.


texts: Identify a surface mount zener diode with a four digits code?

texts:
I'm reverse engineering a circuit which provides a digital signal over a single pin. It is made up of only three components, all of them surface mount.

One component I assume is a zener diode. (The PCB labeled it ZD52)

The component itself has the designation of H2F9.

I couldn't find this code in any code book or key.

How can I find the specs on this diode?

(Circuit Below)

BYC1 - 3 Pin IC. (Unknown Function)
H2F9 - Zener Diode (Assumed)
1300 - 130 Ohm Resistor (Unknown Power Rating)

This circuit connects to the very end (nothing comes after these components in the circuit) of the negative (standard current notation) terminal.

The circuits function is to output a digital signal over the pin I have labeled "Data Output".

I'm not sure exactly sure how the circuit works, as I don't know how the IC works, but I plan on using the same IC, so I just need to match the other components.

Here is a picture of the circuit...

Here is a close up of the IC...

I believe the IC's function is to output a digital signal from read-only memory, over a single line.


texts:
I am not able to find any libraries for simulating accelerometer in proteus. Is there such a library? If NO, how do i simulate an embedded system that has an accelerometer?

Thanks


texts: Isn't the amplification in amps always going towards infinity?

texts:
In my textbook I have a scheme like this:

Which is trying to explain the principle of feedback. So the singal X1 is amplified into X2, part of X2 is returned and added with X1, which is again amplified and so on.... so wouldn't in the end both X1 and X2 become infinite, for a positive feedback?
And for a negative feedback they would become 0, with a similar logic.


texts: Explanation of transfer function from electrical design

texts:
I am a bio-engineer student so not that profound with electric cirquits. But I understand how transfer function works. My problem is the following: I have found a source from literature that derives a transfer function from a given electrical circuit. The electrical circuit is the one I've attached as an image. It is actually a biological circuit based on a model of the mechanics in the lungs.

Now the transfer function from the paper is given by:

It is possible that the above transfer function is incorrect (Rst does appear in the transfer function and not in the diagram, which is weird).
User rioaxe pointed out that the transfer function above is actually the impedance of the circuit, that is Pressure (P) / Flow (F) = Vin / Iin,  which is very logical because the equation relating pressure to flow is:  P = Raw * F,  with Raw the airway resistance. Equivalent to Vin = R * Iin  in electrical circuits.

The problem that I face now is how to derive the transfer function Vin / Iin from what rioaxe has given as answer. I never worked with electrical circuits like that before (in series + parallel).

If someone can help me derive the TF this will be very kind.
And thanks for who already tried to help.
Cheers

Here is a second picture of the (viscoelastic) model:


texts:
Looking at wikipedia on resistivity I see that, other than gold, aluminium is a close second to Copper.

Do any transformers use aluminium windings ? I'm guessing they would be less expensive to come by...


texts:
does anyone knows what type of transistor this is:

DGS
S250
PH1d

Thanks in advance,
Pedro


texts: Comparator circuit to detect working alternator

texts:
I'm very new to electronics, but am trying to build a device that should be attached to a motorcycle (Arduino based sensor board) which should only draw power when the engine is running; specifically given the finicky nature of motorcycle batteries, and that my device will have an approximate two ampere draw.

I've been researching comparator circuits, but it seems as I want to avoid any draw on the battery when the engine isn't running.

I have self-imposed restrictions on specifically not interfacing with any of the bike's other circuitry, mostly because it's brand new, and I don't want to splice/hack into any wiring that might relate to the safety electronics, etc, etc; I can rely on a connection to the battery, and I'm hoping to detect 12v±1v when the motor isn't running, and closer to 14v when the alternator is doing it's job.

I heard a quip that I could use an opamp and a zener to somehow boost a 3v button cell to a suitable reference voltage to drive the comparator, that I might compare  against 13v, for example.

The missing puzzle (in spite of lots of time spent with Google) is how can I use a rechargeable (I expect) button cell at 3v to compare against a 12-14(±1)v input.

Assuming that I detect the battery is currently charging from the alternator, I'll be stepping the voltage down to 5v using a LM2569, which is closer to the button cell's voltage, but doesn't help me to avoid drawing on the battery when the motor isn't running.


texts: Can a capacitor charge and discharge at the same time?

texts:
Is it possible to use the stored energy while the capacitor is being charged?  In other words, use a capacitor almost as a conductor?

My gut says the answer is probably no (and my own experiments so far seems to be justifying my hunch) but if so, I'm very curious on what's actually happening inside the capacitor, in terms of what exactly is blocking the stored energy to not escape (discharge) until the capacitor is fully charged?


texts: Unipolar Hall current sensor signal conditioning for 5v ADC

texts:
Need help. I need to convert signal (0v to 5v) from Hall-based unipolar current sensor measuring the power line from the 84v 4kW battery pack to 5v MCU based ADC converter. Although both – the sensor and MCU-based ADC converter are unipolar, yet their ranges are different and mid-point shifted. This is fairly often needed task yet I was surprised to not find a complete answer neither here nor anywhere else. I have found post here Level shifting pedal output to 0-5V   which largely shows the solution but some issues still remain.
I'll cover whole of the task here so that other people who are searching for the same answers will have all the answers (with your help) here in one place.
I chose the Tamura hall current sensor.

My schematic:

This sensor is similar to the most popular of this type HASS sensors from LEM with similar specs:
Linear voltage output from input current,  open loop , unipolar +5V power, 2.5v reference,
rated output  Vref + 1.5v = 4v (to be used for theoretical calculated calibration), Vout max >= 4.5v
Measured current = 0 outputs 2.5v, saturation current in one direction produces 4.5v max, in another direction gives 0.5v min (hence swings around 2.5v from 0.5v to 4.5v)
Output needs pull down using 10kOm resistor

My chosen op amp AD8052 is rail-to-rail 0-5v (source 5v).
It will measure battery current so it flows in one direction only, I can use either positive or negative direction, I choose direction swing from the sensor from 2.5v (no current) to 4.5v (saturation). But I need a protection from accidental reverse current wire insertion into the hall loop.
Resistors Calculation:
gain G = 5v/(4.5-2.5) = 2.5
G = 1+ R4/R3 = 2.5
Choose R3=100k -> R4=150k
(4.5 – Vref) * 2.5 = (5 – Vref)
Vref = 4.17v
Voltage divider R1=2k, R2=10k will produce ~4.17v

Unsolved "mysteries" :
How does pull down 10k resistor effect the Op Amp input conditioning? Will it change the above calculations?
How to add a protection from reverse hookup of sensed wire (voltage from sensor would fall below +2.5v) ?
I intend to use two sensors for two ranges of sensitivity (100A and 300A), therefore one (100A) is intended to be for a long time in saturation. Will saturated op amp overheat?

Edit: datasheet for the Tamura sensors:
Tamura L01Z100S05 sensor


texts: Troubleshooting connections between strips of WS2811 Addressable RGB LEDs

texts:
I'm hoping for help troubleshooting a light array I built for my son's room. I strung together 8 strips of WS2811 addressable RGB LEDs (30 per strip). I soldered all the strings together, and tested them prior to mounting. Whole strand lit up beautifully. Then, I mounted them onto his desk, and now the first strip lights, and only the first LED of the second strand lights and that one LED is significantly dimmer.

No problem, I think, one of the connections just came loose. But it doesn't seem as though I have any bad solders, and jiggling the wires around doesn't really cause any change in the lone weak LED on the second strip.

I put a multimeter on the end of the first, well-behaved, strip. No value reading across +5V and Gnd. But no reading wouldn't explain how the second strip has one light with some small amount of juice.
I mounted onto the painted wood surface using the adhesive on the back of the strips, and the back does have the exposed copper pads. I figured that the paint on the wood would be sufficiently insulating, but could there be voltage drop from the mounting?
I'm running this with an ESP32, and have a dedicated 5V 2A power supply powering the LEDs.

I'm sure it's a bad solder, but without getting any reading from the good strip's +5V and GND, I'm a little confused. Also, there's clearly some current moving on since the second strip is lighting up a little bit. I'd like to troubleshoot it before I have to unmount the whole dang thing and redo the wiring.

Thanks!


texts: Decipher Serial Port communication log of microcontroller

texts:
I have an old robot (named qu-bot) that I had used in a school project. A few days ago, I began taking interest in Arduino. On closer inspection, I found that the old robot contains the ATMEGA16 chip. The robot came with a software that was used for programming it. It had a rather basic and limited programming language that is useless beyond school projects. But, it has quite a lot of sensors for me to practice on.

I was thinking of uploading Arduino's bootloader on it. A bit of research online revealed that repurposing old hardware often turns out to be a quite difficult task. Hence, the first step I tried was communicating with it on the serial terminal (UART) of Arduino IDE instead of terminal of the inbuilt software.

It turns out, as soon as Arduino's monitor tries to connect to Qu-Bot, it "locks down" itself. All functions stop and LEDs and sensors get turned off. When I reconnect it to inbuilt monitor, Qu-Bot gets "cured".

So, I thought of tapping into the communication going on in the COM port. I tapped into communication of Arduino IDE as well as inbuilt software. However, the report of the tap looks quite meaningless to me.
Can someone please help me decipher the report and tell what is causing the Qu-Bot to "lockdown"?

Report of communication b/w Arduino IDE and bot

Report of communication b/w inbuilt software and bot


texts: Strange oscillations with TL431 voltage reference

texts:
I have a problem with TL431 voltage reference circuit:

There is no load connected to VREF25.
When I remove C8, voltage VREF25 is perfectly stable 2.5V.
But when I put C8 back into the circuit, voltage VREF25 is oscillating and I can't figure out why:

It is irony because C8 was meant to stabilize VREF25.

UPDATE:
I tried to use capacitor with higher capacitance (470nF). It did not help.
I tried to use resistor (R10) with lower resistance (330Ω) to increase current (from 1mA to 2mA). It did not help.

UPDATE2:
3.3V line is this:

I use genuine TL431 from NXP.
There's no 139kHz signal in my circuit. Actually I disconnected this voltage reference from the rest of circuitry.
I use SMD components, capacitors and resistors are 0805.


texts: Would the motor reverse if phases swapped for this case?

texts:
A servomotor power connection pins are given as follows:

U V W are the three phase terminals. Would the motor reverse if I mistakenly swap phases U and V namely if I connect pin 1 to W and pin 3 to U? Is this a synchronous motor or induction?

Motor nameplate:


texts: PHY Link only establishing 10 Mbps speed when both devices 100 Mbps capable

texts:
I've designed a circuit board with a Microchip switch (KSZ9897) going to a Ethernet-to-VDSL module (LX200V20).

The PHY ports between the two devices are connected using a transformerless connection as shown on Figure 4 in this application note (http://ww1.microchip.com/downloads/en/AppNotes/ANLAN120-UNG.pdf).

By default with auto-negotiation & auto MDI-X enabled, the switch establishes a 10 Mbps, full-duplex link. I am expecting a 100 Mbps link since both devices are 100-BaseTX compatible and I've confirmed that by decoding the LCW (link-code-word) from their fast link pulses.

I have also tried a forced speed connection (disabling auto-negotiation). For 100 Mbps & Full-duplex, I can see some idle traffic on both RX and TX pairs, but the link does not come up. For 10 Mbps & Full-duplex, the link does come up and work. I have also tried disabling auto MDI-X, but that does not seem to change much either.

My question is what could be causing the link to only establish at 10 Mbps? I have attached some scope pics to help isolate the problem. The scopes are all from one of the RX/TX pairs between the switch and the AC coupling caps.

Scope 1) Forced 100 Mbps idle traffic
Scope 2) LCW from VDSL module (left burst), LCW from switch (right burst)
Scope 3) NLP (single burst of LCW) from VDSL module


texts: I'm looking to produce an intensely bright single flash exceeding 2000 lumens for half a second. If I hook a charged 10,000uF electrolytic capacitor up to a 100w LED chip, will it work and how bright will it be? Is there a better way of doing this electronically?


texts: Determine the input impedances of a circuit

texts:
I'm studying a circuit with BJT's and I'm asked to determine the input resistances of the two amplification steps of the circuit. The circuit I'm analyzing is the following one:

To determine the input resistances I performed an AC analysis and obtained the following results:

I know that the values are not perceptible but they are Rin1=23.272231 kohm and Rin2=220.77106 kohm.
I decided to choose a somewhat random value in the zone of the graphic where the curves are constant (I'm not sure if this is correct...).

Well this value are very different from what I obtained when I analyze the theoretical values of the input resistances.

Using:

$$R_{i2}=(β+1) R_{E3}//R_L+r_{π2}$$

where r_{π2} is 9.375 kohm and beta is 300.
I obtained R_i2=240.375 kΩ

And for Ri1

$$R_{i1}=R_1//R_2//(r_π1+R_{E1} (1+β))$$
I obtained R_i1=20.183kohm.

I used the small-signal analysis models to determine this...

Now this is odd. I'm getting an error of about 15% on Ri1 and 7% on Ri2. Am I doing something wrong or are this deviations perfectly normal and dependent on the methods used on the theoretical analysis and on LTSpice. Can someone help me clarify this?


texts: How Can I Design a Non-Inverting Active High Pass Filter?

texts:
All the active filters I've found 0n books and google are inverting type (i.e. input signal is applied at the negative input pin of the op-amp).
I thought if I apply the input signal at the positive terminal, it may work as a non-inverting high pass filter. But the frequency response (Proteus 8.6 simulation) looks like a low pass filter.
As my power supply is either 0-5 or 0-3.3 volts, I need to design a filter that does not create a negative output voltage. Plus I'll connect the output to a microcontroller ( or Arduino), which also can't have negative voltage.
Can anyone help me by providing a circuit diagram of Active Non-Inverting High Pass Filter?


texts: How do you choose an inductor for connecting separate ground planes?

texts:
On a board with separate analog and digital ground planes connected at one place, the connection is often made with an inductor. How is this inductor chosen? Obviously it has to be able to handle enough current, but what other factors are important?

I'm more interested in the type of inductor rather than the value, since I would expect to try different values.


texts: Physical stability of different surface mount footprints

texts:
While looking for rotary switches to use as user inputs to a processor, I came across these three footprints:

I'm considering using a surface-mount part for board layout considerations, but am concerned about physical stability with repeated adjustment.

To me, the through-hole part seems vastly more able to withstand repeated torques, but what about the two surface-mount footprints? Which one is going to be stronger against a twisting motion?


texts: Voltage or Current Control with a Microcontroller for Pressure Regulator

texts:
I am wanting to control the flow rate of a pressure regulator (https://www.festo.com/net/SupportPortal/Files/505126/VEAB_2018-05a_8080669g1.pdf). My idea is to control this with a PWM signal 0-5v.

The signal requirements for the PPR is either a voltage of 0-10v or current controlled 4-20ma.

Option 1:
Now if you had a MCU with PWM could you use put a 125 ohm resistor to the input of the regulator if it was current controlled? As at 0.5v you have 4ma and at 5v you have 20ma.

Option 2:
I could use a mosfet but I am unsure on what I a looking for if I want use one. I know the VGS(th) must be less than 5v to be used for a MCU but how do I know how much voltage will flow when the voltage at the gate is 1v or 5v?

I am open to what you guys think could be best and any help would be appreciated.

Cheers


texts: How do I extend the number of analog (input) pins available to me?

texts:
I already know how to extend the number of digital pins on an Arduino using a multiplexer.

I want to increase the number of analog input channels that I have. One solution is to add another Arduino as a slave.

How would I increase the number of analog input channels? (I assume some MUXing and ADCs are involved). If it's too complicated to write in an answer, a general outline of circuit/code would be fine as well.

I am also open to shield suggestions, though I'd prefer it if there was a not-too-hard hardware solution.


texts: ESC Output Current for a Brushless Motor with a Given Max Current Rating

texts: I am trying to power a brushless motor with a max current consumption of 12.5 A (specified in datasheet). How should I figure out the maximum current drawn by one of the phases of the ESC? Should I just divide the max current draw of the motor by three, or is the solution more complex?


texts: What is max Vce for a transistor with Ic of 50 mA and without exceeding PD(max) of 1.2 W?


texts: Unable to verify Superposition Principle via Matlab

texts:
I am dealing with this problem where I want to verify the Superposition Principle via Matlab.

I have a DC source of 100V, an AC source of 50V, 60Hz and three resistances, R1=10 ohms, R2=20 ohms and R3=15 ohms. (Refer circuit diagram)

Now, the Principle of Superposition states the total current in any part of a linear circuit equals the algebraic sum of the currents produced by each source separately. I am trying to verify the current flowing through R3 = 15 ohms resistance.

I short circuit the DC voltage source and run the program. Result:

I then short circuit the AC voltage source and run the program. Result:

As clearly can be seen, the Superposition Principle is not verified. I am unable to reason where the discrepancy is.

However, when taking both sources as DC or AC, the Principle is verified. Any help regarding this is appreciated.


texts: How do I condition a signal with an op-amp that needs a negative rail where one is not provided?

texts:
I am working on a water monitoring system that needs to read ph in ADC of microcontroller(0-3.3V)

I understand how ph sensors work...just -.41V(0ph) to +.41V(14ph)...

I have an understanding of designing the circuit to amplify and scale this so that the microcontroller can read it.

Is there a significant advantage using a 5V microcontroller to get a larger voltage range? The micro I want to use is 3.3V with max 3.6V on the ADC, 12 bits. If I chose a 5V micro or off chip ADC, would I get more accurate results? Obviously the amp circuit will be a factor here, but consider it the same circuit with different gains etc...
How can I supply negative voltage to the op amps? This will be in an embedded system and will have access to 120VAC input. Are there negative voltage regulators that supply enough power for an opamp and that can get me negative voltage w.r.t ground?


texts: Transistor - Why does amplification happen before the transistor and not after?

texts:
I know this is a noob question but I just can't find an answer for it on google search results.

Well my question is basically this: How come the amplifying occurs before the transistor [red line] and does not occur after the transistor [blue line]? I was thinking that the current had to go though the transistor to be increased.


texts: How to create a design that uses specific % of DFF and LUT count in FPGA to measure power dissipation?

texts:
I want to create a design which does not perform any specific useful function but utilizes specified amount of logic resource in the FPGA e.g 50% DFF and LUT or 50% DFF and 25% LUT e.t.c. I shall then perform power measurement across the different rails with and without PLL e.t.c.
Is there a practical way to do this? I need to take measurement across several FPGA families and compare them across three vendors.


texts: What is the difference between reg and wire after synthesizing?

texts:
Assuming i have these two codes:

module wire_example( a, b, y);
  input a, b;
  output y;

  wire a, b, y;

  assign y = a & b;

endmodule

and the second one is:

module reg_combo_example( a, b, y);
input a, b;
output y;

reg   y;
wire a, b;

always @ ( a or b)
begin
  y = a & b;
end

endmodule

my question is what is the difference in the net list, both of them will have an gate, but will the module with reg y will have a flip flop or a latch to hold the data while wire y won't have any latch?


texts: Can I change laptop's RTC and backup battery with generic Ni-MH?

texts:
I got old laptop for a good price. After some inspection, I noticed that backup battery and RTC battery are already gone bad, and seems can't hold charge. I've checked eBay for replacements, but only got 2.4V RTC batteries.

So, it seems that these are just plain Ni-MH cells without any circuitry. Therefore, I'm gonna buy some small Ni-MH cells and fabricate one. Is it okay to do this?


texts: Producing a VHDL design unit from a State Diagram

texts:
I need help understanding a stateflow diagram.
I'm supposed to design it in VHDL as a beginner's exercise.

I've gone through the VHDL tutorials on nandland.com, and could say I understand the basics of VHDL.

What I don't understand is what this state diagram means.

Could someone help me with that? You don't have to write the code, I just need to know what the diagram means.

Noob question, I know. But I'm new to this.

Thanks in advance.

Edit:
Here's where I got the question from. The question says I should replace X with 0.


texts:
I'm trying to make (and try to learn something better) about a simple current regulator.
I need to make a complete static analisys before starting with the frequency one. But I've some thoughts about how the base current will introduce errors and how a series resistor to the base will make it vary.

The circuit is this (available already made on the web, but with quite silly descriptions..). The values are not quite meaningful, because I'm still at literal calculations.

simulate this circuit – Schematic created using CircuitLab

Here I've some troubles to extrapolate all the Kirchoff equations to analyze all the parameters (static ones) and so how Rb will influence the circuit.

For example, I find this:

Ib = Vbe/(Rb-Rs) - Rs*Id/(Rb-Rs)

where Id is the current flowing through the MOS M1.

But from here I recognize that Id = Vbe/Rs if we neglect the base current.

How can I give some meaning to the Ib equation, if it is correct? Should I fix the drain current then make the analisys? Of course, if I substitute the Id with Vbe/Rs, Ib will be 0, so the equation seems to be correct. But how to consider Id with the base contribution? Any help from where to start?


texts: Does the excess(unused) part of a wire have any resistance effect

texts:
Let's say I am trying to calculate and measure the resistance of a wire that I know the cross-sectional Area and length. Does the excess part as seen in the image effect the length? And should it be taken in to consideration when doing the calculations? Or because there is no current passing through, can it be omitted?
 This is a noob question I know, but i need to be sure.

simulate this circuit – Schematic created using CircuitLab


texts: How to control a capacitance control panel from a Raspberry Pi

texts:
I have a touch control panel with only one lead going to each "button" on the glass, it is not a full circuit only half of one.

I have concluded if i ground one of the pins (ex: power), it senses and activates the "button". I need to figure out a way to control this from a raspberry pi. I do believe some sort of transistors would be ideal.

I need to know how i can send a signal from the Raspberry Pi's GPIO pins to activate some sort of switch that grounds that lead. basically to trick the control panel into a button click. I have looked into relays but if i can do this without moving parts that would be ideal!

Please help! Thank you all for reading
-Matt

P.s. i tried this and it did nothing


texts:
I need a motor and I'm not sure what to be looking for. I know the power and torque I need (3 N*m @ 1200 rpm = 1/2 HP). Is finding a motor as simple as matching these two values?

Edit: The motor will be used essentially like a fan motor; It will have to maintain a (fairly) constant speed for long periods of time. It's power will come from the wall (120V) so it could probably be AC but doesn't have to be. It'll be sitting still at room temperature.

I'm mostly trying to understand how to choose a motor based upon torque/power requirements as I don't know what I'm doing when it comes to this.

EDIT: I can incorporate something like a gearbox, I just don't know the process of picking a motor + gearbox that does what I actually want.


texts: Can I ground AC voltage sources when I do DC analysis of differential amplifier with BJT and current mirrors circuits?


texts: I have a quick question on 2-1 multiplexers

texts:
So say we have a 2-1 MUX with

\$D_0=GND\$,
\$D_1=Q_0\$ and
S=X.

Questions:

The output equation will be \$Q_0X\$, correct?
Now if we change \$D_0\$ to Vdd instead of GND, what happens?

If X=1 the output will be \$Q_0\$, but if X=0 the output will just be logical 1.

Would the equation be \$Q_0X+\bar{X}\$?


texts: How about ground pouring under an electromechanical relay?

texts: As known, it's not good to route noise sensitive signal traces under relay. Then what about ground pouring under the relay? Is it good or not?


texts: Is the natural inductance of circuit parts a problem, and if so, how do you combat it?

texts: Every circuit component always has some small property of every other component like resistance or capacitance or inductance. However, one thing I noticed is that it's possible for a spontaneous change in the current to overheat a part of a circuit, and it would seem this would be due to the component's natural tendency to resist changes in current, aka inductance. At what point is this a problem in a circuit, and how can it be overcome?