Tag Info

1

It's no different to using a chip to reverse a motor. It's called a H bridge. Here's one that should work: - You'd need an inverter to drive one of the inputs but other than that it emulates a DPDT relay.

1

Do I need to amplify the signal? It might be wise to measure the output signal. PC's can have at least three types of analog audio output (plus things like USB speaker outputs): line-out (consumer "line-level" signals to e.g. powered monitors) earphone/headphone output. speaker output for unpowered speakers. Some of these may need amplifications, ...

4

When using a red and green LED, you can utilize the difference in LED forward voltage as in the circuit below. Make sure to use high efficiency LED's. These have a low internal resistance and a nice and sharp bend in the forward voltage/current curve. simulate this circuit – Schematic created using CircuitLab Normally the green LED lights, ...

1

I bet the idea below can be optimized further, but I don't have time right now to improve it. How about this proof of concept: simulate this circuit – Schematic created using CircuitLab Not the most power efficient solution with the resistive divider, but cheap solution and requires only two leads to the LEDs.

1

This might be helpful if you are looking for a pure analog solution without logic gates/relays or integrated circuits. simulate this circuit – Schematic created using CircuitLab Disclaimer: This answer is purely from an academic perspective. Consider that it may be wrong and/or not safe for practice. Any harm caused from building and operating ...

0

Here is a solution based on a DPDT relay (long version of Ignacio's comment I guess :-)

1

To keep it "analog", you could use two op-amps connected in a bridge-tied-load configuration, but configured as comparators. When one comparator swings high, the other swings low and vice versa, i.e: simulate this circuit – Schematic created using CircuitLab This is how you get the voltage to reverse. If the IN voltage is above VREF, then it ...

3

This seems to be a problem I've seen a few times on stack exchange. Consider an op-amp with localized negative feedback - The manufacturer designs the op-amp so that under the very worst case situations it is stable. The worst case situation is unity gain - this has the biggest chance of being unstable. Anyway, each year the boundaries get pushed a bit more ...

2

A true digital signal is a list of numbers. Consider digital signal processing which has, as input, a list of numbers and, as output, a different but related list of numbers. When one uses a spreadsheet to find a moving average of the DJIA, one is doing digital signal processing. Also, remember that, abstractly, the contents of computer memory is just a ...

2

Power Conversion The input voltage to a computer power supply is 120V AC in the US, where the "AC" stands for Alternating Current. It alternates 60 times per second, or 60 Hertz (Hz). You could say that this is an "analog" source, because viewing it on an oscilloscope or a graph over time, it's a sinusoidal wave. If you measure the instantaneous voltage at ...

1

If you are looking for a specific OpAmp chip I'm sorry, I'm not familiar with any 3.5 V ones. About other things, if it will be a battery driven device make sure the input impedance is high ( to consume less current ). Usually (extra) high input impedance OpAmps are doing worse with noise characteristics, but if that's not of terrible importance the trade ...

1

I'll try to go through the question section by section and explain mistakes shown in the logic, if there are any. We know that the 120v from the wall is analog And the digital one that the components will use (transistors, diodes, etc.) will look like this: Yes, that could be considered correct. That would imply that an ADC circuit must be ...

4

Your logic is somewhat sound in assuming that an Analog to Digital conversion is happening, but there is a big set of steps that you are missing. Suffice it to say that this answer section is not sufficient to describe fully how a computer takes a 120VAC signal coming out of a wall and turns it into the webpage you are looking at. Turning the 120VAC signal ...

0

For safety only! The circiut has a ground that you defined and the osciloscope's signal is biased with the two pins. Remember that the power generator and the osciloscope cannot be earth grounded at the same time because you will have a short circuit when measuring a signal of a single component in a circuit.

1

On a few oscilloscopes, each channel will independently measure the voltage difference between the inside and outside of a BNC jacks without allowing any current to flow between the different jacks. More commonly, the outer ring of all the BNC connectors will be connected together. Typically, for scopes with a three-prong mains plug, they will be connected ...

1

There are two 'ground' points in play here: Earth ground is for safety. Connect to earth ground if you like. Signal ground is for measurement. Connect to a ground on the circuit you are testing. Preferably something near the signals you want to probe. The signal input of the scope has two front panel BNC connectors for probes. When you connect the ...

1

The earth ground pin of the power supply is for safety only, it does not have any impact on the signal measured by your scope probe. The scope channel input measures the voltage between the two pins of the BNC, the inner pin and the outer pin (acting as a shield). You must always connect the two to get a proper voltage, because a voltage is the difference ...

0

Stay close to DC and this is a question of output impedance of your sensor. If you use a simple inverting op-amp configuration like this, you will have R1 as load for your sensor output. Suppose you have R1=1K/R2=10K and 100R output impedance of your sensor. That would not give you 10x gain but more like 10/1.1 ~ 9x. You can have a much higher impedance ...

0

It seems a lot of trouble to go to when quite possibly a single resistor might work. The data output from the CD4012D shift register in the game pad will offer an impedance to the data line when it gets plugged in. Based on this "theory", if you had a pull-up resistor in your detection module (the bit you are adding) then when the game pad is not inserted ...

1

If I understand you correctly, in your test you essentially apply a voltage to the reference input, but leave the cathode open? That's outside the Operating Conditions (p. 2, bottom), which require a minimum of Vref. So as far as the manufacturer is concerned, anything can happen. What I think happens is that the reference input is now powering the chip ...

0

The 3 headphone buttons you referred to do not pass information digitally, but are being signaled electronically using change of resistance, as explained here: How do volume control headphones work? In the case of the headphone buttons, you can say information about pressed buttons is being passed "out-of-band" - it doesn't occupy the audio in or out ...

Top 50 recent answers are included