DC-->AC? (1 Viewer)

[Speed6]

I have encountered a problem whilst doing an independent investigation whilst using a homemade battery cell with soft drinks. The problem is that the cell produces only DC voltage and a small LED I have only seems to work in AC. My question is that how can I convert it to make the LED work in DC...

 

[seventhroot]

you can't made LED's work on DC unless you use a rectifier iirc (something like that)

 

[Speed6]

you can't made LED's work on DC unless you use a rectifier iirc (something like that)

What very low voltage ~1-.5 can I power something with DC?

 

[anomalousdecay]

I have encountered a problem whilst doing an independent investigation whilst using a homemade battery cell with soft drinks. The problem is that the cell produces only DC voltage and a small LED I have only seems to work in AC. My question is that how can I convert it to make the LED work in DC...

What the....

LEDs are diodes so they work in DC (exception of zener diodes which can actually go back the other way with a high enough voltage). If you are running an LED of AC, then either it is flashing at the frequency of the AC signal or if it is straight lit up for the whole time then most likely you have some sort of converter, or rectifier circuit, or filter circuit, or you are using a circuit that converts AC to an RMS voltage value (highly doubt you have done any of this though).

What voltage is your battery giving out (check with a voltmeter please)? Typical LED's have a voltage drop of 0.7V so you need at least 0.7V potential in your battery to light it up to begin with!

 

[anomalousdecay]

you can't made LED's work on DC unless you use a rectifier iirc (something like that)

wot

 

[Speed6]

What the....

LEDs are diodes so they work in DC (exception of zener diodes which can actually go back the other way with a high enough voltage). If you are running an LED of AC, then either it is flashing at the frequency of the AC signal or if it is straight lit up for the whole time then most likely you have some sort of converter, or rectifier circuit, or filter circuit, or you are using a circuit that converts AC to an RMS voltage value (highly doubt you have done any of this though).

What voltage is your battery giving out (check with a voltmeter please)? Typical LED's have a voltage drop of 0.7V so you need at least 0.7V potential in your battery to light it up to begin with!

.700V for the lemonade cell.

 

[seventhroot]

wot

I don't even electrical; yet

 

[anomalousdecay]

.700V for the lemonade cell.

At 0.7V it might only slightly light up. An ideal voltage for a bright LED would be something around 3V.

If you wanted to use AC then you would have to make something like this, but keep in mind that you need at least 3V to make the LED light up with a bit of intensity that makes it easy to tell its lighting up:

In this configuration, you would want at least 4V AC.

Note that there are diodes and an LED there. The diodes have a voltage drop of approximately 0.7V. Once you reach 0.7V, effectively a diode acts as a short circuit.

 

[anomalousdecay]

Btw that's called a full wave rectifier. You'll get the LED to flash at the frequency of the AC signal which is pretty cool.

 

[Speed6]

Btw that's called a full wave rectifier. You'll get the LED to flash at the frequency of the AC signal which is pretty cool.

But man can't I power anything with a low voltage DC?

 

[anomalousdecay]

But man can't I power anything with a low voltage DC?

Yes it might be powered, but there is no kick in it to make it obviously visible its being powered.

Also, LEDs work differently. You need minimum 0.7V and then will it start increasing in intensity.

 

[Fizzy_Cyst]

You, my friend, have broken fizzicks! Are you sure you have connected the LED the correct way? One way they will work, the other they won't

 

[Speed6]

You, my friend, have broken fizzicks! Are you sure you have connected the LED the correct way? One way they will work, the other they won't

Fak, a fizzycist is telling me I've broken fizzicks. I'm so sorry Einstein.

What colour LED can be powered on a low voltage DC?

 

[theodore0307]

you cant

 

[Speed6]

you cant

Please elaborate

 

[Fizzy_Cyst]

Longer wavelength LEDs require lower voltages, but even red LED's still require ~2V

 

[theodore0307]

At 0.7V it might only slightly light up. An ideal voltage for a bright LED would be something around 3V.

If you wanted to use AC then you would have to make something like this, but keep in mind that you need at least 3V to make the LED light up with a bit of intensity that makes it easy to tell its lighting up:

In this configuration, you would want at least 4V AC.

Note that there are diodes and an LED there. The diodes have a voltage drop of approximately 0.7V. Once you reach 0.7V, effectively a diode acts as a short circuit.

Because we understand this

 

[anomalousdecay]

Because we understand this

Yeah...... lol

I can explain what questions you might have about it. If you know how a diode works briefly (they only allow a flow of current in the forward biased direction, where you connect the negative terminal to the cathode (flat edge of the LED) and the positive terminal to the anode, but in reverse bias they don't allow for current flow), then you apply the same principle to a diode.

After all an LED is a diode that emits light.

Longer wavelength LEDs require lower voltages, but even red LED's still require ~2V

This is true as less energy is required to liberate LEDs with longer wavelengths of light emitted.

However on a side note, I've had a green led which I bump up to 9V and it starts emitting orange light instead lol. Cool thing is that the LED doesn't actually pop or burn out if I just tap it for a few seconds or something. I have no idea why it went orange though since orange light has a larger wavelength than green light Need your help on understanding what is going on with that. And I'm also assuming this particular LED allows all wavelengths of light through rather than cutting off at 590 nm and below as expected of some green LEDs.

 

[braintic]

Why don't you just buy more soft drink and make more batteries?

 

[Speed6]

Why don't you just buy more soft drink and make more batteries?

Too late lol, the science fair has already past, waiting for my final results and verdict which should be delivered to the school sometime.