need help making circuit!!!

Ron H

Joined Apr 14, 2005
7,014
i dont mean to sound nagging but will the circuit work even if the speed control puts out 0.01v? its hard to explain what i mean
Yes. If the speed control voltage is below 2 volts, the lights will be on. Otherwise, they will be off. Is that what you want?
 

Thread Starter

vane

Joined Feb 28, 2007
189
will it need LEDs that will run off 7.2 volts then? cause im going to get a bulk pack of 100 ultra bright LEDs off ebay, thanks i may need a little bit of help.
 

Ron H

Joined Apr 14, 2005
7,014
will it need LEDs that will run off 7.2 volts then? cause im going to get a bulk pack of 100 ultra bright LEDs off ebay, thanks i may need a little bit of help.
Post the link to the Ebay LEDs, or post a datasheet or a link to it.
 

Ron H

Joined Apr 14, 2005
7,014
Vane, I changed the schematic to handle your LEDs (before, I had guessed at what you were using). I had to add 2 resistors in order to handle the 25 milliamps per LED. I also changed some resistor values, so you need to look at your parts list carefully.
It should now work with the LEDs you referenced on Ebay. If those aren't the same ones, tell me now! It makes a difference! I was surprised you chose clear ones.
You should use 1/4 watt resistors for R8 and R9. The rest of them can be 1/8W or 1/4W.
You don't need to buy anything else special.
 

hgmjr

Joined Jan 28, 2005
9,029
Ron,

I believe I noticed the specifications further down in the link vane provided. It just takes a bit of scrolling to locate it.

hgmjr
 

Thread Starter

vane

Joined Feb 28, 2007
189
they are maximum 3.8v forward voltage are they alright?

"** Free Postage **
Product Description

*
Emitted Colour : WHITE
*
Size (mm) : 5mm
*
Lens Colour : Water Clear
*
Peak Wave Length (nm) : N/A
*
Forward Voltage (V) : 3.2 ~ 3.8
*
Reverse Current (uA) : <=30
*
Luminous Intensity Typ Iv (mcd) : Average in 5000
*
Life Rating : 100,000 Hours
*
Viewing Angle : 20 ~ 25 Degree

Absolute Maximum Ratings (Ta=25°C)

*
Max Power Dissipation : 80mw
*
Max Continuous Forward Current : 30mA
*
Max Peak Forward Current : 75mA
*
Reverse Voltage : 5~6V
*
Lead Soldering Temperature : 240°C (<5Sec)
*
Operating Temperature Range : -25°C ~ +85°C
*
Preservative Temperature Range : -30°C ~ +100°C"
 

recca02

Joined Apr 2, 2007
1,214
hey a piece of advice from me.
after you finish the circuit.
for once try making the same project with a comparator its shud very
be easy. even a non electronics student like me can make it.
 
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