# Tag Info

1 vote

### How would I have to modify this headphone amp circuit to increase the output power of one channel?

This is where an oscilloscope comes in really handy. You have a good channel and a bad channel. Use the oscilloscope to trace back from the headphone jack back to the ADC output. At each stage you ...
• 58.2k

### Which of the following is correct?

welcome to Stack Exchange. Let me help you answer this. With regard to your second statement, it is indeed false, as the DC operating point must be found to determine the AC small signal parameters of ...
1 vote

### Switch power to load using 2 GPIO pins, 5V and 12V

One problem with your circuit is that you would not be able to turn off the PMOS given that your GPIOs can drive up to 3.3V only, when high. When GPIO13 and GPIO18 are driven low, no issues, the PMOS ...
• 5,100

### Node voltage - I am having trouble making my system of equations

@ashiningjewel Your first equation is correct. Your second equation, however, is not right as you should be consistent about the signs. It should be $$\frac{V_2}{2}-\frac{V_{1}-V_{2}}{5}+5=0$$. Be ...
1 vote
Accepted

### ESP32 + ST7735S display circuit diagram

I soldered small wires to the module and connected them to a breadboard then tested the uart programming using the Arduino IDE and output a serial message once booted. Once the module is powered it ...
• 23

### Current surge protection for relay contacts when closing

I'll show you a naive MOSFET based current limiter, but it may be more of a liability than a solution, depending on how big those capacitors are. simulate this circuit – Schematic created using ...
• 7,975

### Current surge protection for relay contacts when closing

I have used a simple current limiter circuit such as the following, which limits charging current to about 8 amps: Upon further investigation, I found that this would not be useful when the capacitor ...

### Running 15 amps through a 10 amp switch to power a 13 amp circuit?

Is the switch I was given able to handle the current? It will work well for a while, then the contacts will die or weld themselves shorted. Do I have to find a way to reduce the current, so the ...
• 59.1k

### Running 15 amps through a 10 amp switch to power a 13 amp circuit?

A DC power supply often see a capacitive 0 charge on switching. Thus the ESR of the load cap and supply can be much less than <<0.1 Ohm and the switch must handle this contact turn on current ...

### Running 15 amps through a 10 amp switch to power a 13 amp circuit?

You need a better switch to handle the 13A. That doesn't mean you can't also use the switch you are given. If for example it is the only one that fits on the front panel of your device (and fits ...
• 2,572

### Running 15 amps through a 10 amp switch to power a 13 amp circuit?

No. Switch is rated for 10A, not 13A. The load takes 13A at 24V. It might not work properly if you limit current to 10A. Depending on what the load is, it may not be possible to reduce current. If ...
• 89.3k

### Running 15 amps through a 10 amp switch to power a 13 amp circuit?

1: No. The switch says 10 amps; 10 amps is less than 13 amps. 2: It's hard to "reduce the current" going through the switch. It's not so much putting a flow restrictor washer in your ...
• 7,200

### "Unknown subcircuit" error in LTSpiceXVII

It's just telling you that there's no .SUBCKT (or internal model) for the OPAx227. This is probably because the text you added (over there on the far right side, that is cut-off so I can't really read ...
• 70.2k

### For below circuit, the simulation result is not matching with theoretical prediction

The right-hand C has no charge at t=0 (L is short circuiting it at t<0), therefore this C looks like a short circuit at t=0. The upper C is charged to V, with + on its left-hand plate. This is the ...
• 7,274

### For below circuit, the simulation result is not matching with theoretical prediction

That's not the correct answer. I won't spoil it for you, but your approach with shorted inductances and opened capacitors is the right way to go. Then your LTspice approach is not correct, either. ...
• 17.7k
Accepted

### For below circuit, the simulation result is not matching with theoretical prediction

At $t=0^-$ right before the switch opens, we're at DC steady state, so inductors are shorts and caps are open. The top capacitor has charged to voltage V, which means no current flows in the ...
• 59.1k
1 vote
Accepted

### Wiring a headset with push-to-talk functionality to a standard TRRS connector

Generally the headset wiring diagrams seem to use speaker ground for mic ground too, and the PTT wire just connects the PTT pin to the ground. This is proven by your test because mic always works, it ...
• 89.3k

### Norton's equivalent circuit - current through short circuit

If you look at the answer. The Norton current is 5 ampere which you can also calculate like you said "why not all the current is flowing from the short circuit well if you calculate it. It will ...

### Norton's equivalent circuit - current through short circuit

If the 12 ohm resistor is replaced with a short circuit then you would have no resistance and no voltage drop, but the current would flow. You can make the circuit a bit simpler and remove/delete all ...
1 vote

### How to design a circuit that will trigger after a specific delay once a push button is pressed

You could do this with a single 74HC123 and two RC circuits, one for the delay (perhaps 2M/1uF) and one for the pulse (perhaps 2M/100nF). RC time constant are not optimal, that's ballpark. Film ...
• 331k

### How to design a circuit that will trigger after a specific delay once a push button is pressed

Solution with discrete components simulate this circuit – Schematic created using CircuitLab Just for people, who don't want to see NE 555 in each circuit. D2 and V5 just simulate a long ...
• 1,889

### How to design a circuit that will trigger after a specific delay once a push button is pressed

Circuits with microprocessors or digital counters will give the most accurate results but you asked for an analog solution. Assuming this is a one-off hobby project and your requirements are somewhat ...
• 2,032
Accepted

### How to design a circuit that will trigger after a specific delay once a push button is pressed

You can do this with 555 timers as others have said (you could also do it with discrete transistors) the biggest problem being the capacitor values needed for relatively long time delays. You can get ...
• 4,140

### How to design a circuit that will trigger after a specific delay once a push button is pressed

How accurate to the delay and output pulse periods have to be? +/xx% - ? +/-xx milliseconds - ? oes the 10 second delay start at the beginning of the input pulse, or at the end of the input pulse? ...
• 12.8k
1 vote

### How to design a circuit that will trigger after a specific delay once a push button is pressed

You’ll need two timers, one for the delay and one for the pulse. Long delays (like 10s) are hard to generate reliably with an analog solution because of the large values needed for R and C. I suggest ...
• 40.5k

### Op-amp boost pedal tonal noise

You use model train power supply. Those supplies often contain no capacitors to filter the rectifier output. I assume that the OpAmp is fed with 100 Hz pulsing DC, a proper voltage regulator is ...
• 1,889

### Op-amp boost pedal tonal noise

As @Jens suggests "greatly" ... A good power is needed. Here is a picture for "explaining" somewhat the "spectrum" of the output. NB: it is only for one configuration of &...
• 4,762

### Op-amp boost pedal tonal noise

To start, I would change C5 and C6 - a lot. As shown, the filter at C6 has a lowpass corner frequency of 22 kHz -ish. This will do nothing to reduce hum on the DC power source. As it is, incoming ...
• 12.8k

### Op-amp boost pedal tonal noise

You can try lowering the values of the voltage divider resistors, or better yet use a regulator. As it is you are dropping 6 V across 4700 $\Omega\$ which give you \frac{6~V}{4700~ \Omega} = 0....
• 4,140

You have an "external" memory interface either way. The array in VHDL is referenced by an index, and you pass the index you want to read or write through a ...
• 10.3k
1 vote

### Discharging RC circuit for bi-directional solenoid?

A single relay would do. On energising the relay, the capacitor charge-pulse would latch the solenoid. On de-energising the relay or powering off, the capacitor discharge-pulse would unlatch it.
• 10.4k
1 vote

### Can circuit without memory give output depending on the order in which input pins were activated for non-commutative operations?

If it really has no memory elements -- neither explicit nor implicit ones -- then no, it cannot remember the order of events. A system has memory if and only if its present behavior is influenced by ...
• 36.3k
1 vote
Accepted

### Can circuit without memory give output depending on the order in which input pins were activated for non-commutative operations?

A purely combinatorial circuit, i.e. one without ANY feedback, when it settles after an input change, will have an output that depends only on the inputs, and not on the history of the inputs. However,...

Cache misses? The ADC runs on the DMA, and if it doesn’t – change it so it would. It should be paced by a timer. No per-sample interrupts. What exactly is the MCU and the board you’re using? This ...

### Discharging RC circuit for bi-directional solenoid?

From what you are saying, there's still a significant chance that the "hold-up" (aka energy storage) capacitor could get discharged too quickly before the Arduino had a chance to revert the ...
• 384k
1 vote

### Node voltage - I am having trouble making my system of equations

You did an excellent job, except for an incorrect sign in just one place. Let me teach you a different approach that will help you avoid such mistakes. But beforehand, let me redraw the schematic so ...
• 70.2k

### Node voltage - I am having trouble making my system of equations

Your equations are summing the current out of each node. Take a look again at how you handled the two ideal current sources, and note the direction of each current.
• 29.6k
1 vote

### How to get rid of floating voltage on Bridge rectifier

There is no ghost voltage, it can be calculated exactly. The channels without AC input receive half wave rectification through the other rectifiers with input. I just have drawn 2 rectifiers in detail ...
• 1,889
1 vote

### What are the markings on this PCB?

The markings are not very relevant. This is a 4-layer board and you'll have to reverse-engineer it, i.e. figure out the connections, and re-draw it using KiCad (realistically). The board looks to be ...
Accepted

### Trouble finding LDM for EMI filter

You're making it seem more complicated than it is. All two-port inductors are "differential mode" by definition. They can't be anything else: for common mode you need 4 ports at least. LDM ...
Accepted

### What are the markings on this PCB?

It appears to be an industrial control board made by Siemens, which may include a Modbus interface. You'd have to ask Siemens what the markings mean, or find a circuit diagram or device guide that ...
• 58.2k

### BQ51051B or BQ51050B communicate but won't charge

I did solve the problem, the TS pin was not welded properly so the resistor 10kohm was not connected to the IC hence not letting the IC to charge properly
1 vote

### Designing MOSFET bridge rectifiers for high voltages

This rectifier may not work as you expect or need. The MOSFETs will turn on and conduct for the appropriate leg of the circuit, but unlike a conventional rectifier, they will remain conducting on the '...
• 13.9k
Accepted

### Unlatch a bi-directional latch when power is lost?

Here's the schematic. At power on, the relay K1 is energised and its 'NC' contact is open. When the solenoid unlatch coil is energised, the electrolytic capacitor gets charged. When power fails, the '...
• 10.4k

### Detect how many push buttons are being pressed using a maximum of two Arduino pins

You can use an I2C IO expander powered by 5V. Connect the two IO pins of the Arduino to the I2C SDA and SCK lines. Use the 5V power to power the expander chip. Something like the MCP23008-E/P costs ...
• 9,737

### Detect how many push buttons are being pressed using a maximum of two Arduino pins

With 8 buttons there are 255 possible combinations of presses. Consider an R-2R ladder. If the uC has a 10 bit A/D, you should have enough resolution to determine the input voltage to a 1-in-255 ...
• 12.8k

### I get a high cutoff frequency value

I think I see what the problem is now. You are using an .AC analysis, but you are changing a specific frequency, which means you're interested in a ...
• 17.7k
Accepted

### Can we use an integrator circuit as a Hilbert transformer?

Phase shift? Sure. That's the easy part. Or flat amplitude response. Trivial. How do you do both at the same time? That's the tricky part. Typical implementation is a chain of all-pass filters, thus ...
• 2,433