Simple LED circuit

I'm trying to put together a simple diorama for my son's school
project and may have bitten off more than I can chew... my electronics
knowledge is basically zip but was trying to make something a bit
special for him. What I'm trying to do is this:
In a cardboard box that the diorama is in we have 8 animal figures
that will each have a LED beside them and then on the front of the box
beside the viewing window I want to have 8 on/off buttons each
corresponding to a particular LED in the model so when the kids press
the button labeled say "T-Rex" the LED beside the figure in the box
will light up. Kinda like the scenes you'd see in a museum display.
I was going to use a 9v battery and I do know I'd need to insert a
resistor from the battery before the LED's but was wondering if anyone
could possible describe the simplest way of wiring it all up.


thanks so much in advance,
regards
Rod

 

[KLR]

On Mon, 17 Nov 2003 10:06:16 +1000, rjcreative@austarnet.com.au wrote:

I'm trying to put together a simple diorama for my son's school
project and may have bitten off more than I can chew... my electronics
knowledge is basically zip but was trying to make something a bit
special for him. What I'm trying to do is this:
In a cardboard box that the diorama is in we have 8 animal figures
that will each have a LED beside them and then on the front of the box
beside the viewing window I want to have 8 on/off buttons each
corresponding to a particular LED in the model so when the kids press
the button labeled say "T-Rex" the LED beside the figure in the box
will light up. Kinda like the scenes you'd see in a museum display.
I was going to use a 9v battery and I do know I'd need to insert a
resistor from the battery before the LED's but was wondering if anyone
could possible describe the simplest way of wiring it all up.


thanks so much in advance,
regards
Rod

you would need about 470 ohm resistor if dropping from 9v DC.


Make sure that the short leg of the LEDs goes to the (-) supply of the
battery - bring the + side of the battery to one terminal on all the
switches - take a wire from the second terminal of each switch through
a 470ohm resistor to the appropriate LED.


Not difficult

 

[Dan Marz]

Rod,
to do what you need is simple enough. You need to include a 330 ohm 1/2
watt resistor in line (i.e. in series) with each Light Emitting Diode
(LED). Be aware that there is a positive and negative on the LED.

So the wiring goes from (+) of the battery to the push button switch
terminal, then from the other switch terminal to the 330 ohm resistor
and the other end of the resistor to the longer of the two leads of the
LED. The shorter LED lead then goes to the battery (-) terminal.

You then repeat this for the other 7 displays, have fun!

Daniel

rjcreative@austarnet.com.au wrote:

I'm trying to put together a simple diorama for my son's school
project and may have bitten off more than I can chew... my electronics
knowledge is basically zip but was trying to make something a bit
special for him.

 

[Dan Marz]

KLR wrote:

you would need about 470 ohm resistor if dropping from 9v DC.

Not if you want 2 volts across the LED with 20mA current. 470 is OK but
330 is best. Just double checked the DSE specs pages, P308 of the 2002
catalogue also says 330 ohms.


Don't confuse the poor guy, he is trying to help out the kids.

 

Cheers Dan, that's just what I was looking for, thanks so much for the
help.

regards
Rod

On Mon, 17 Nov 2003 12:18:05 +1100, Dan Marz
<medcircDELETETHIS@tpg.com.au> wrote:

Rod,
to do what you need is simple enough. You need to include a 330 ohm 1/2
watt resistor in line (i.e. in series) with each Light Emitting Diode
(LED). Be aware that there is a positive and negative on the LED.

So the wiring goes from (+) of the battery to the push button switch
terminal, then from the other switch terminal to the 330 ohm resistor
and the other end of the resistor to the longer of the two leads of the
LED. The shorter LED lead then goes to the battery (-) terminal.

You then repeat this for the other 7 displays, have fun!

Daniel

rjcreative@austarnet.com.au wrote:
I'm trying to put together a simple diorama for my son's school
project and may have bitten off more than I can chew... my electronics
knowledge is basically zip but was trying to make something a bit
special for him.