20
votes
Accepted
Which wire is hot?
Which wire is hot doesn't matter. According to the schematics in the service manual, both wires from the power plug go straight into the transformer (via the fuse and switch.) If hot/neutral ...
- 69.1k
8
votes
Accepted
Is touching a neutral wire safe?
Some people say that touching a neutral in this case will lead to the same result as touching the hot wire because it is AC and current path changes 100 times a second (we have 50 Hz.) Others say that ...
- 69.1k
5
votes
Is touching a neutral wire safe?
For being shocked, you should allow enough current to flow through your body from the touch point (neutral wire and your finger) to the point where you are standing on (earth). Since your body will ...
- 30.2k
4
votes
Is touching a neutral wire safe?
It is absolutely NOT safe. In SOME countries the neutral goes to a local ground, but that may be some distance away and there can still be some 50V rms or so on that pole, which is still enough to ...
- 6,604
4
votes
Is measuring 220v AC current from wall socket with multimeter safe?
There are several hazards to be aware of.
Probes overheating? The probes, like the current input on the meter, are good for the rated 10 amps. The meter is reading 1.6 amps, so there is plenty of ...
- 162k
4
votes
Accepted
Is measuring 220v AC current from wall socket with multimeter safe?
It is safe if you are aware of what you are doing.
The probes won't overheat when used within the ranges specified.
Don't touch the metal parts of the probes when they are in contact with live wires - ...
- 6,519
4
votes
How to sense the presence of AC voltage that could vary from 17 V to 230 V?
I would be inclined to use a circuit something like this.
simulate this circuit – Schematic created using CircuitLab
The key is a depletion mode N-channel MOSFET, which has a negative VGS(th) ...
- 27k
4
votes
How to sense the presence of AC voltage that could vary from 17 V to 230 V?
The simplest way to limit optocoupler LED current when driven with AC is a capacitor in series, as in the usual capacitive dropper power supply. This is not dissipative, which is good. Unfortunately ...
- 71.9k
3
votes
How to sense the presence of AC voltage that could vary from 17 V to 230 V?
I started off by looking at what others have done, and I found a good source of ideas at the ESP website (Rod Elliott). In particular this link:
https://sound-au.com/appnotes/an020.htm
...and figures ...
- 1,522
2
votes
How to sense the presence of AC voltage that could vary from 17 V to 230 V?
One approach would be to use a small and inexpensive (eg. 1W) isolated DC-DC converter so you have a power supply bus on the high voltage side.
You can then detect the voltage with a simple low-power ...
- 383k
2
votes
Should Liquid Level Sensors be supplied AC or DC
The circuit is a simple water level sensor that works on DC.
When probes touch water with ions, small current can pass through water to transistor which turns on. Water is used as kind of resistance.
...
- 137k
2
votes
How much clearance do I need for a terminal block that will run at 240VAC, 10A max?
IPC-2221 table 6.1 lists a few numbers that will be of interest. In particular is the column B2 for soldered pads to other non-protected copper and, column B4 for tracks under solder resist (permanent ...
- 443k
2
votes
How can I convert a Noma Ornamotion Christmas tree ornament motor to USB power?
I did this a long time ago with transformers. Sorry, I don't remember the transformer part number, but I matched the voltage as close as I could. I may have used 1/2 of a center tap.
I also have some ...
- 14.9k
2
votes
Can we sell 110V equipment without NRTL certification in a US market?
Yes, you can sell it. The NRTL is enforced at a local level and a legal liability (cover your butt). As far as the local enforcement goes, OSHA requires product testing, so any organization that needs ...
- 78k
2
votes
Can we sell 110V equipment without NRTL certification in a US market?
There is no US federal law that requires it. Your customer may require it for insurance or other reasons, or it might be required by city or state regulations.
Consider FCC and other regulations too.....
- 383k
2
votes
Accepted
Circuit that outputs signal A when AC sine is positive and signal B when AC sine is negative
Op-amp precision rectifiers are the likely turn-to solution. Here's an example circuit: -
When the input is positive, the op-amp is prevented from creating an inverted (negative) output by D1 but, ...
- 443k
1
vote
Accepted
Multisim simulation insight
If "j * omega" ... is an inductance ...
And 4*V is a "step generator" ...
Then I could write these equations: Made with Maple ...
i1 (left-high loop), i2 (left low loop), i3 (right ...
- 11.9k
1
vote
Accepted
Residual current relay continuity
The RCD should not be damaged by triggering at its design leakage trip point, as long as the interrupted current is within the design range. Most devices will have durability limits of 1000s of trips.
...
- 5,761
1
vote
Accepted
Do Kirlian setups work with DC power?
According to this paper, Kirlian photography will work with DC.
There's mention of some differences between Kirlian pictures made using AC and Kirlian pictures made using DC.
The polarity of the ...
- 69.1k
1
vote
Is touching a neutral wire safe?
You can touch whatever you want: As long as you are floating, no current will flow through you. See birds, for example.
If you are touching other things, like door frames, other appliances, or even ...
- 19.6k
1
vote
Airport runway lighting: What is constant current in relation to alternating and direct current?
Most of the time we deal with constant voltage supplies, for example you might have a 12 V supply, and the current in the circuit will depend on the resistance as described by Ohm’s Law I = V/R. So ...
- 19.5k
1
vote
Should Liquid Level Sensors be supplied AC or DC
You should use something like this, working as AC sensor (could be simplified).
C5 is the variable capacitor. Can be also a resistor.
- 11.9k
1
vote
Can I give DC 12V to a AC 12V input?
Linear regulators like 7812 needs 2v or more above the output voltage as input in order for them to work properly. Example, you want a regulated 12v dc output, you have to at least give an input of ...
- 11
Only top scored, non community-wiki answers of a minimum length are eligible