Resistors and Capacitors - Electronic Circuits Projects Diagrams Free

mettam · 7th July 2006, 07:45 AM

I have learnt that a capacitor charges and discharges over time so with that in mind is it possable to run a 9Volts through a capacitor and have a LED flash on and off.
Or maybe a I would need to use both a resistor and a capacitor.
I did it with a 555IC but it seems it should be achievable just with just a R and C.

I hope this question isn't to basic for this forum..

Justin.

RadioRon · 7th July 2006, 07:56 AM

When put together with a resistor or LED, a capacitor will indeed charge OR discharge over time, but will not charge AND discharge over time. So it will charge up to 9 volts only once and then stay there. At the very beginning of this when you first apply the voltage, the LED might light a tiny bit and very briefly but only that once and nevermore. There will be no flashing unless you add additional stuff (like the 555) to do some additional switching.

Overclocked · 7th July 2006, 08:22 AM

The 555 timer takes the ramp signal from an RC circuit and converts it to a square wave signal. The signal goes from 0 to VCC, if the signal is slow enough (less than 30 Hz) you can see the LED blinking.

However, if you want to use the ramp signal, it will give the LED a Fading in and out apperance. See this circuit for more info
http://ourworld.compuserve.com/homep...5.htm#eyes.gif

I myself have used that circut and it is visually Appealing.

(the above needs grammer checking, its 3:30AM in the morn.. But you get the idea)

k7elp60 · 7th July 2006, 02:11 PM

Just get a flashing LED, it will work right off 9 volts with no other parts required. The flashing circuitry is built into the LED.

Rolf · 7th July 2006, 03:08 PM

Radio Shacks flashing LEDs requires 2.5 - 5v, typical 3v. Have not tried them at 9v, seems a little high for the specification.

k7elp60 · 7th July 2006, 11:17 PM

I didn't consider the Radio Shack ones. The ones I use are from Mouser Electronics and they have a typical operating voltage of 3V min and 14 volts Max. The forward voltage affects the fash rate.

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7th July 2006, 07:45 AM	(permalink)
mettam	Resistors and Capacitors I have learnt that a capacitor charges and discharges over time so with that in mind is it possable to run a 9Volts through a capacitor and have a LED flash on and off. Or maybe a I would need to use both a resistor and a capacitor. I did it with a 555IC but it seems it should be achievable just with just a R and C. I hope this question isn't to basic for this forum.. Justin.

7th July 2006, 07:56 AM	(permalink)
RadioRon	When put together with a resistor or LED, a capacitor will indeed charge OR discharge over time, but will not charge AND discharge over time. So it will charge up to 9 volts only once and then stay there. At the very beginning of this when you first apply the voltage, the LED might light a tiny bit and very briefly but only that once and nevermore. There will be no flashing unless you add additional stuff (like the 555) to do some additional switching. __________________ RadioRon

7th July 2006, 08:22 AM	(permalink)
Overclocked	The 555 timer takes the ramp signal from an RC circuit and converts it to a square wave signal. The signal goes from 0 to VCC, if the signal is slow enough (less than 30 Hz) you can see the LED blinking. However, if you want to use the ramp signal, it will give the LED a Fading in and out apperance. See this circuit for more info http://ourworld.compuserve.com/homep...5.htm#eyes.gif I myself have used that circut and it is visually Appealing. (the above needs grammer checking, its 3:30AM in the morn.. But you get the idea)

7th July 2006, 02:11 PM	(permalink)
k7elp60	Just get a flashing LED, it will work right off 9 volts with no other parts required. The flashing circuitry is built into the LED. __________________ The great thing about electronics is unlimited ways to do the job. The only limit is one\'s imagination. I generally think my way is best. Show me a different way. I have an open mind.

7th July 2006, 03:08 PM	(permalink)
Rolf	Radio Shacks flashing LEDs requires 2.5 - 5v, typical 3v. Have not tried them at 9v, seems a little high for the specification. Last edited by Rolf; 7th July 2006 at 03:12 PM.

7th July 2006, 11:17 PM	(permalink)
k7elp60	I didn't consider the Radio Shack ones. The ones I use are from Mouser Electronics and they have a typical operating voltage of 3V min and 14 volts Max. The forward voltage affects the fash rate. __________________ The great thing about electronics is unlimited ways to do the job. The only limit is one\'s imagination. I generally think my way is best. Show me a different way. I have an open mind.