how to detect Ac

[Gayan Soyza]

Hello guys can anybody tell me whats the meaning of "The Occurance Of Ac Voltage , And When Ac Disrupt Occur " ?

 

[khatib]

thanks for all

 

[Mike_2545]

It certainly DOES MATTER which way you hook it up. Connect the lower line on the diagram to the "active" wire of an AC outlet and you are directly connected to 120v or 240v.

That's why you should not give advice unless you have actually tested what you provide.

It has been and is tested, collin: but thanks for your input on the subject!

 

[shingadaddy]

UH..UHmm. Well I guess we gave the whole Enchilada instead of just enough food for thought. At least it didn't go RUBE GOLDBERG on us.

And I thought blueroom meant he stuck a coathanger in a light socket.
and DETECTED AC volts!!

 

[KMoffett]

I think it a little less then 1.44 W. more like 422.5 Milliwatts but any way I let it stay on for a hour with just a half watter 10 k and it didn't get hot

120VRMS/10kΩ=0.012mA
120VRMSx0.012mA=1.44W

???????

You no phone's have them Optocouplers in them to pickup the ring-signal AC wave it can be up too 90 volts

"AC" or pulsating DC?

Ken

 

[blueroomelectronics]

And I thought blueroom meant he stuck a coathanger in a light socket.
and DETECTED AC volts!!

Yes I did, when I was 5.

 

[be80be]

It's 120 volts Ac I showed you the plug and the led lit. Your getting about 65 volts if the line is 60hz I'm not going to play with 120 volts DC . Any way I checked it with vom It's
422.5 Milliwatts

coathanger in a light socket

I had a boy that worked for
me he would lick a 9 volt battery if it shocked him he say that 1 was good. The pump went out on his water well. He check it the same way it almost killed him

 

[shingadaddy]

Me too Blueroom!

Well all I'll say -- about the whole thing is --

Shocking. Simply shocking.

be80be- Whats the part number of your L.E.D ?

 

[KMoffett]

It's 120 volts Ac I showed you the plug and the led lit. Your getting about 65 volts if the line is 60hz I'm not going to play with 120 volts DC . Any way I checked it with vom It's
422.5 Milliwatts

Still a little baffled. Most every LED that I'm familiar with have a Vrev-max of 5V. You say you are placing a standard red LED, in series with a 10K resistor, across a 120VAC outlet, and it's working OK.

Does this seem strange to anyone else?

Ken

 

[be80be]

They use them as panel lamps all the time **broken link removed**the led is blinking at 60 hz**broken link removed**
I'm getting less then 20 ma current to the led. Current thew the led is what would blow it I'm way ok here. I could have used a 5.6 kohm didn't have 1

 

[shingadaddy]

Forward makes sense. And after all it IS a diode and is blocking the current on one direction and doesn't have to work too hard at it since the reverse leakage current is probably enough that the resistor is soaking up / limiting the effective reverse voltage to a possibly tolerable level. Resistor only takes a beating - er a - heating at 50% duty cycle and at a halfasine duration only.

At first it does It does conjure up an instant vision of :

vvvfffvvvFFFRAP---POP--- sizzzzzzle.

Hence, my signature phrase

 

[KMoffett]

Forward makes sense. And after all it IS a diode and is blocking the current on one direction and doesn't have to work too hard at it since the reverse leakage current is probably enough that the resistor is soaking up / limiting the effective reverse voltage to a possibly tolerable level. Resistor only takes a beating - er a - heating at 50% duty cycle and at a halfasine duration only.

Take a look at any discrete LED spec sheet. "Absolute Maximum" Vrev=5V. (Ok I did find one that had Vr=9V) The Irev at Vrev is usually 100µA. So using your concept: 10K x 100µA would drop 1.0V across the resistor. That leaves 119V (actually 169Vpeak) reverse voltage across the LED.

Still doesn't make sense.

Ken

 

[shingadaddy]

LED - 10K 1/2 watt resistor and a suicide cord and you have the test set.

Give it a whirl.

Thats why I wanted the LED part number so I could check to see if its one with a built in resistor and a non-typical voltage rating.

FLASH! Maybe its one of those fancy smancy LED's that actually have 2 diodes on the die. One in each direction.

 

[KMoffett]

If it had a built-in diode, with its polarity opposite the LED, it would work. I don't recall seeing ever seeing one like that. But then, I haven't seen everything...yet.

Ken

 

[KMoffett]

OK I did a bench test. But, no way I'm going to do the 120VAC/resistor/LED trick.

Normal forward bias connection of a red LED with a current-limited power supply: Vf=1.9v@If=20mA

Reverse Connection: Ir=~0 mA @ Vr <24V. As Vr was increased above 25V, Ir rapidly increased to 30mA. The LED was getting hot!

A combination of the 10K resistor limiting the reverse current to 12mA (120v/10K) would keep the LED from going Poof. But this cannot be doing the LED any good in the long run. A single diode, connect with opposite polarity across the LED would make the LED operate within its specified limits.

be80be,

Do you have any examples of this configuration used in commercial, or hobby, devices?

Ken

 

[be80be]

I'm done with the Led and 120 volt's now i don't no what you tired a diode blocks half of the 120 volts because it's AC so it only using 60 volts now the led will not burn up because I limited the Current to about 6mA. So it can't be getting hot. It's the current that burns the led out and most any small diode can handle 120 volts at less then 20 mA. And a led is a diode. Oh by the way if you have not seen them They are selling light bulbs with led in them $35.00 each lol and the one's I put in couldn't have more then a resistor and some led's in it. Oh what I showed you was real a cord plugged in to the wall outlet with a led hooked to a 10k resistor and and hooked to the cord and plugged in to the AC 120 volts
LED; Red, T- 1 3/4 (5mm); Super Brite, 6.3 mcd, Diffused Lens
$0.12 (Each) that's what it is

____________________________________________________
**broken link removed**

 

[shingadaddy]

The double direction (or dislecsic) diode is a " you can't get it backwards" design and glowage is ensured no matter which way it gets stuck in the circuit.

Ken I figured you tried the 120 volt test and that was what brought the electro-tech website down around 4ish central time today. I didn't hear a big bang though

 

[be80be]

lol It just a plain red led like you get from radio shack. no tricks It just works. Here there using a 6 watt lamp for the resistor Ultra-simple Voltage Probe - RED - Page25

Just remember that this non-linear relationship between voltage and current means that Ohm's Law doesn't work for LEDs.

 

[KMoffett]

Thanks!

Ken

 

[umer27]

before I shoot myself for reading all posts on this topic...

here is your solution, Buy an AC relay ... like the OMRON MY2 or MY4 ... it has a switching time of 20 ms.. so its pretty quick.. hope you know how, a relay works.. and if your using a u controller, how to properly use the signal..

PS.. i really deserve getting an upgrade in Reputation for this post ! (see, Im a good boy now.. )