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0 votes

How to find phase shift from oscilloscope?

A good thing to do would be to calculate these expressions by hand instead of relying on the scope to do the work (it becomes important to double check equipment) Magnitude is simply the height of the ...
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0 votes

Ripple voltage filtering capacitor

For reference, I am too "lazy" applying some formulas I forget easily. So, I check always with my favorite simulator I know since ever ... Made with microcap v12, interactive mode. Some ...
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1 vote

Can I get this motor to run AC?

Don't do that. That microwave turntable motor produces 120V on its terminals when you turn it only slightly. As the gearbox ratio is that high. But you can also turn it rather fast and then it has ...
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0 votes

How do you combine 2 AC power sources?

simulate this circuit – Schematic created using CircuitLab The reason you don't get 220V is that the incoming AC supply and the inverter(s) are wired in parallel, not series. If your supply is ...
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0 votes

How to detect the shorting/elimination of a 250 mA load in a 20 Vac circuit?

Maybe something along these lines could work. You would need to tune the R and C values to make sure it can detect your shortest pulse. A bleeder resistor on the cap could also help with that if the ...
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0 votes

How to detect the shorting/elimination of a 250 mA load in a 20 Vac circuit?

Use a 12VAC coil relay with a ~10V bipolar TVS in series (or two Zener diodes) simulate this circuit – Schematic created using CircuitLab
0 votes

How to detect the shorting/elimination of a 250 mA load in a 20 Vac circuit?

All that would be required is a relay with a 20 V AC coil. Edit # 1 Alternately use a standard 24V DC relay and two 1N4007 diodes. Edit # 2 Thanks to Bruce Abbot. Use a bridge rectifier in lieu of ...
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4 votes
Accepted

Sparking when using multimeter

Most multimeters have 3 sockets to connect the probes: One is negative for all measurements. One is positive for all measurements except 10A current. One is positive for 10A current measurement only. ...
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2 votes

Sparking when using multimeter

Q: it possible you made a mistake? It certainly sounds like it was set to read current or you shorted it by accient without noticing. A: Set for Voltage, AC and the range setting was 600VAC. ...
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0 votes

Battery replacement for 16 VAC

The easiest approach (but not the cheapest) if AC is really required is to obtain a low wattage 12VDC to AC mains inverter and then use it to drive a mains to 16V (or similar) transformer. If you ...
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3 votes

Ripple voltage filtering capacitor

Filtering capacitors have same exact rules as any other capacitor, it's just called a filtering capacitor because it acts like a simple filter. In fact, a capacitor used after a bridge rectifier is ...
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16 votes
Accepted

Ripple voltage filtering capacitor

I've included a snapshot, of sorts, so that you can see what's happening better: On the main diagram, I expanded out a rectangle and placed it over to the right side so that you might see a little ...
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3 votes

Ripple voltage filtering capacitor

Consider the characteristic time constant for an RC circuit: $$\tau = RC$$ where \$R\$ is the resistance of the load connected to the output. Its value must be higher than the period of the ripple (...
4 votes

Ripple voltage filtering capacitor

For a first order approximation, you assume that the capacitor charges for a tiny fraction of the cycle, and it discharges for almost the entire time. Cap equation: \$i = C \frac{dv}{dt}\$ If the ...
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3 votes

Ripple voltage filtering capacitor

"the filtering capacitor...after a diode bridge can...effectively convert the current from AC to approximatively DC." The bridge rectifier takes an AC voltage and outputs a sort of pulsing ...
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4 votes

Converting 24 VAC to 5 VDC with small output current

simulate this circuit – Schematic created using CircuitLab Here's what you get with the existing circuit and a nominal 50mA approximate load (I've changed D1 to a 5.6V Zener and C2 to 1000uF). ...
2 votes

Converting 24 VAC to 5 VDC with small output current

I take it you realise that it is ok to draw less current from that power supply than the 300mA maximum that it is capable of supplying and the reason you want to redesign it to have a smaller current ...
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2 votes

Converting 24 VAC to 5 VDC with small output current

Can anyone explain the formula for calculating the capacitance needed to achieve a final result of 5 V, 30 mA coming from 24 VAC, 0.33 A? \$X_C\$ is the impedance of a capacitor (in Ohms) at some ...
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8 votes
Accepted

Converting 24 VAC to 5 VDC with small output current

Unless you have a reason to limit the current it makes no difference if a power supply is capable of more current than you need at a given voltage, if a device draws 50 mA at 5 V it will draw that ...
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3 votes

Converting 24 VAC to 5 VDC with small output current

The circuit looks as if it should work as it stands. C1 is acting as a series impedance, similar to a series resistor, but without the dissipation. D2 clips the sine waves at 5.1 V, the current ...
12 votes
Accepted

Purpose of capacitor connected across AC input in a smart bulb?

Without further analysis, the LED lamp has a switching power supply, and switching power supplies have mains filter caps to make the lamps fit to current electromagnetic interference standards. Cheap/...
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10 votes

Purpose of capacitor connected across AC input in a smart bulb?

This is most likely used for noise suppression. That is: it reduces the amount of noise that is generated by the lamp from getting back into the AC Mains. This is only a guess on my part, but I ...
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0 votes

Isolated AC line voltage monitoring circuit

The best solution I have found is to use a transformer. Once the primary is connected all of the voltages are low and isolated. Transformers have a fixed ratio between the primary and secondary, this ...
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2 votes
Accepted

Is this method of proving energy is conserved in an LC oscillator correct?

but we know that the power factor of an LC circuit is zero, which means \$\frac{dU}{dt}=0\$ No it doesn't. The LC circuit is lossless, which means that average power is 0, i.e. $$<u(t)i(t)> = 0 ...
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-1 votes

In a single-phase transformer output, which-wire would be phase, and which-one would be neutral?

I use a no-contact AC tester (12-600 VAC), even though the secondary is floating with no ground. There is a Hot lead and there is a Neutral lead.
1 vote

AC signal switch with MCU

You could use a DPDT analog switch IC or some logic to make one. There are many varieties and sources for them. I do not know your resources so I will not venture a guess. I would switch the signal ...
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0 votes

Multiple AC-DC power supplies: one direct AC wall plug or two?

The overall power consumption of your devices is about (multiply voltage and current) 15 W + 60 W + 60 W + 48 W = 183 W There will be additional conversion losses for the power supplies. Let's assume ...
1 vote
Accepted

Externally sensing if AC current is being drawn over a power cord

I'd try putting a coil or a Hall effect sensor near the cable (ideally right on the cable). Emphatically not a toroidal current transformer. You don't want to measure both the live and neutral wires ...
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1 vote

Externally sensing if AC current is being drawn over a power cord

A current transformer and some circuit to interface it to your MCU should do it. A Hall effect sensor is another option. If you're trying to detect current in a typical AC power cord you're going to ...
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1 vote

Can 12V/9V DC source be used for Christmas Disco Light instead of 220V AC?

No, if those are really SCRs, then it won't work. The SCRs need the voltage to go to zero to turn off. You could add a circuit that constantly interrupts the "PWR" signal going to the LEDs. ...
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1 vote

Can 12V/9V DC source be used for Christmas Disco Light instead of 220V AC?

Your circuit relies on thyristors (aka SCRs) to switch the LEDs and, because it uses thyristors, the anode current has to return to the low milliamps to low tens of milliamps for the thyristor to ...
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1 vote

How to add a DOWN limit switch to a Harbor Freight (Pittsburgh) hoist

I added S4, the 2nd limit switch. Probably you need an additional wire between S1 and the wiring box.
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0 votes

How to add a DOWN limit switch to a Harbor Freight (Pittsburgh) hoist

The limit switch goes between the top right terminal of S1 and the wires that currently connect to there. This means you'll need to upgrade the handset to a 5 conductor cable. Or maybe not, I don't ...
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0 votes

How to add a DOWN limit switch to a Harbor Freight (Pittsburgh) hoist

simulate this circuit – Schematic created using CircuitLab Figure 1. Redrawn schematic. There's something wrong with your wire tracing, I think. Both capacitors are in parallel and aren't in ...
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1 vote

AC to DC 6 V for bicycle and super capacitors for lights

I assume, you don't need the standby light function immediately. I replaced your charge diode by a resistor R1. Using this you can charge the supercapacitor slowly with low current. This additional ...
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1 vote
Accepted

Problems running 110 V and 24 V PLC signals in same cable

Around here, code prohibits mains voltage and low voltage wires sharing the same conduit or the same cable. One reason is that low voltage signals will be connected to devices which expect low voltage ...
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1 vote
Accepted

If the current has changed directions, why is it still positive in a negative half wave rectifier?

Be aware that some simulators change the current direction with a change of resistor "direction". It is the reason for the change of the "resistor" shape ("+" pointer). ...
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3 votes

If the current has changed directions, why is it still positive in a negative half wave rectifier?

The current measurement through diode is obviously made from anode to cathode direction, so in that notation, current through diode is always positive through forward direction, because a diode will ...
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1 vote

AC to DC 6 V for bicycle and super capacitors for lights

Capacitors don't regulate voltage, so you can't regulate voltage with a capacitor. With a suitable charging circuit, similar to rechargeable batteries. Maybe a constant current circuit with a voltage ...
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0 votes

"Pull-Down Resistor" in AC circuit

Put a resistor around 10k+ between the input and power ground pins of the shelly. You can also add a diode like a 1N4148 to the input.
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