Help needed - very simple wiring diagram

[masterjedi322]

Just make sure you wire up the batteries such that you get the voltage you are looking for. Some battery holders have the batteries wired in series, so for the example of 2 AAAs, you'd get 1.5 V + 1.5 V = 3 V. However, if they are wired in parallel, you'll just get 1.5 V with double the current capacity.

Sean

 

[Sulla]

OK, I am using 5 mm LEDS (radioshack # 276-041) with a diode forward voltage of 2.6 and a 10mA, with a source voltage of 3 volts from a small single disk battery.

Plugging this into the wizard here's what I got:

Solution 0: 1 x 1 array uses 1 LEDs exactly
+3V

<IMG height=35 alt="-|>|-" src="http://led.linear1.org/i/wiz/wiz-d.png" width=35>

R = 47 ohmsThe wizard says: In solution 0:

• each 47 ohm resistor dissipates 4.7 mW
• the wizard thinks 1/4W resistors are fine for your application
• together, all resistors dissipate 4.7 mW
• together, the diodes dissipate 26 mW
• total power dissipated by the array is 30.7 mW
• the array draws current of 10 mA from the source.

I bought a 1/4W 10 megaohm resistor. When I hook the LED directly to the battery it lights up. When I introduce the resistor to the NEG end of the LED, I get nothing.

Did I get the wrong resistor?

 

[feek61]

You have the wrong resisitor!!!! You need a 47 ohm NOT a 10 megaohm. Thats about 200,000 times too much resisitence, lol, that's why it won't light-up; not enough voltage. Be careful hooking the LED directly to the battery; it will burn it out in no time. Really you should not do that at all!


Will

 

[deck5]

Did I get the wrong resistor?

Yes, by a factor of about 200,000. Note "R = 47 ohms". 10 megaohms is 10,000,000 ohms.

 

[Sulla]

s'what I thought...

Back to the shack.

 

[Sulla]

Looks like radio shack only has 10ohm 1/4W or 100 ohm 1/4 what. i thought I was buying the 100 ohm one. Ah well.

I need to find a brighter LED anyways. What do i need to look for for a very bright red LED?

 

[deck5]

Looks like radio shack only has 10ohm 1/4W or 100 ohm 1/4 what. i thought I was buying the 100 ohm one. Ah well.

I need to find a brighter LED anyways. What do i need to look for for a very bright red LED?

You can wire five 10 ohm resistors in series, that'll give you 50 ohms. Likewise, two 100 ohm resistors wired in parallel will give you 50 ohms.

 

[Sulla]

Like this:

Or like this:

 

[Montagar]

First pic is parallel, second is series.

 

[trekker670]

Slightly off topic, but very similar.

I'm working on converting one of the electronic massaging hairbrushes into a Dermal Regenerator. I'm at the point of redoing the electronics and have a few questions. It's got a pre-existing battery holder for 1 AA battery, however for 2 blue LED's it needs around 3.5 V, so according to the instructions and website I need a 6V camera battery, resistor, and a 1/2" brass spacer. Using the given link I've determined which resistor I need, but I'm not sure where I can get the spacer, any ideas.

Here's the schematic:

 

[feek61]

What do you need the brass spacer for? Is that only the negative connection?


Will

 

[trekker670]

The battery compartment is made to accept 1 AA battery, but the LEDs require over 3V of power so a 6V camera battery is needed, which is smaller than the AA. I guess the brass spacer is to complete the connection of the battery. (current flows through the brass so it basically makes the battery larger in size)

 

[feek61]

Ok, I got ya! You are using the existing battery holder; right? Can't you just get a peice of 1/2 stock (Aluminum would work just fine) and cut it off to the correct length?

 

[trekker670]

Yup, using the existing one. I think I found a hardware store that should have something that will work. Thanks for the help!