[Robotgroup] LED's and Resistors?

[Andre Lamothe]

The 4.5V should be regulated from the power supply, that's all I meant. And 
yes, Radio Shack "should" have these, else MC howards will, else, I will 
bring a bunch next week to the meeting...

Andre'

----- Original Message ----- 
From: <john at cozmicfunk.com>
To: "The Robot Group Mailing List" <robotgroup at puremagic.com>
Sent: Thursday, April 03, 2008 5:29 PM
Subject: Re: [Robotgroup] LED's and Resistors?


Right on, thank you.

One thing I am learning is I can Never be Specific enough with this group, 
to re-iterate:
*
A string of White LED'S in parallel from a 4.5 volts DC source. I am hooking 
up the Additional Flashing Circuits (not one flasher LED!) down the string. 
*Yes, I do not want the other White LED's to flash, that is my problem, and 
not wanting to overdrive the flashing circuits either.

The lights have already been installed, I can Not run any additional wires 
through the Model set, I have to add these Flashing Circuits to the exisitng 
wiring or make a separate battery box again just for 3 new units. Regarding 
Andre's info below:

Can I get these (1N400x) @ Rat shack?

<But, its input (the 4.5V) needs to be regulated, since the regulation of 
the the output is only as good as its input>
*I am not clear on this: do I need some extra diodes to regulate the 4.5 
volts?*
-J


>From xmas light power supply

+4.5V ------------------------ +D1- ----------- +D2- ------------------>3V
Output

-(GND) -------------------------------------------------------------------*

Where D1 and D2 are 1N4001 diodes or similar (1N400x) the various "x" change
the current rating. And + means anode, - means cathode (the side with the
line).



Gray Mack wrote:
> I am assuming that you only want the one led to blink
> and not to cause the whole string to blink, for that,
> a transistor or 555 IC circuit might be better.
>
> Another option (since you usually use batteries to
> power your stuff) is to run a tap at your battery box
> so that only 2 of the 3 AA batteries are running to
> your 3 volt blinking led. The tap wire runs out to
> wherever the led is on your string. You may even be
> able to use the same power switch in the battery box.
>
> -Gray
>
> --- "john at cozmicfunk.com" <john at cozmicfunk.com> wrote:
>
>
>> Hey there. I have a basic question for anyone who
>> can help.
>>
>> I have a 4.5 volt (3x AA) DC powered LED circuit
>> with White LED's (x-mas
>> lights string from Walgreens etc.) and I am adding 3
>> volt Red LED
>> flashing circuit to it. I need to step down the
>> voltage reducing the
>> input for the flasher to 3 volts ( obviously
>> reducing 1.5 volts from the
>> input).
>>
>> I have a couple different flasher lights and LED
>> compartments (all 3
>> volt DC) I am adding down the line for my hallway
>> sections on my models
>> sets. I understand there is color coding on the
>> resistors, which ones
>> should I get and where do I find them, Rat Shack ,
>> Fry's etc.
>>
>> This should be simple for people like Andre and Vern
>> and Done and Gray etc.
>> Thanks, John
>>
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