One hundred and one LED''s
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Posts: 46,084
At 03:18 PM 11/18/00 -0500, you wrote:
>
> Hello everyone,
> I've been given a task which requires lighting approx.
>100 LED's from a large 6V battery. Although the circuit will be controlled
>by a micro, I just need to switch them all on and all off. My question is:
>Is there some way I can wire them in series (to simplify hand wiring them)
>that will avoid the use of current limiting resistors? ie. can I use the
>LEDs themselves to drop the voltage...I'm trying to avoid a one
>resistor/LED scenario and I don't want a circuit that has 100 parallel
>connections...
>
>Best regards, Duncan
Duncan:
Can you use a 12 volt battery? If so, I'd split the LEDs into 2-50 lamp
strings, each with a steering diode. Then pick up one of the cheap 12VDC
to 120VAC inverters and a common lamp dimmer. The two parallel strings,
one running on the positive half cycle and one on the negative should make
a very nice resitive load for the dimmer. The LEDs like any diode has a
non-linear resistance curve, so I'd still put a single resistor in series
with the dimmer control. For the resistor, start with a small 120 volt
lamp, say 15-25 watt size.
Buy the dimmer with the rotary click switch- not the push click- that way
you have no chance of starting it too hot.
Using AC makes it easy to use a solid-state relay for switching direct from
the micro.
Wayne Roderick P.E. (EE, ret)
CEO, Teton Short Line, (NMRA life-1721)
e-mail tetonsl@i... Pocatello Idaho, USA
http://www.ida.net/users/tetonsl/railroad
Note new URL- /biz/ becomes /users/
>
> Hello everyone,
> I've been given a task which requires lighting approx.
>100 LED's from a large 6V battery. Although the circuit will be controlled
>by a micro, I just need to switch them all on and all off. My question is:
>Is there some way I can wire them in series (to simplify hand wiring them)
>that will avoid the use of current limiting resistors? ie. can I use the
>LEDs themselves to drop the voltage...I'm trying to avoid a one
>resistor/LED scenario and I don't want a circuit that has 100 parallel
>connections...
>
>Best regards, Duncan
Duncan:
Can you use a 12 volt battery? If so, I'd split the LEDs into 2-50 lamp
strings, each with a steering diode. Then pick up one of the cheap 12VDC
to 120VAC inverters and a common lamp dimmer. The two parallel strings,
one running on the positive half cycle and one on the negative should make
a very nice resitive load for the dimmer. The LEDs like any diode has a
non-linear resistance curve, so I'd still put a single resistor in series
with the dimmer control. For the resistor, start with a small 120 volt
lamp, say 15-25 watt size.
Buy the dimmer with the rotary click switch- not the push click- that way
you have no chance of starting it too hot.
Using AC makes it easy to use a solid-state relay for switching direct from
the micro.
Wayne Roderick P.E. (EE, ret)
CEO, Teton Short Line, (NMRA life-1721)
e-mail tetonsl@i... Pocatello Idaho, USA
http://www.ida.net/users/tetonsl/railroad
Note new URL- /biz/ becomes /users/