|
LED (Light
Emitting Diodes) Circuits Page 1c
LED: # A
B C
D - E F - H
I - K L
M - O P- R
S T
U - V W -Z
Last Updated on:
Wednesday, November 29, 2017 05:40 AM |
| Circuits Designed by Dave
Johnson, P.E. : |
- 0.5V
Negative Supply
Although not very efficient, this simple circuit, consisting of two LEDs and a photo
diode, generates a negative voltage with a current level of a couple milliamps.
It is ideal for supplying a negative rail to low power “rail to rail” op amp
circuits, which need to have a true zero volts output.
|
-
1W White LED Night Light
As many of you
know, I have a pet peeve with poorly made LED night lights. Often, the light
from the LED quickly fades, so within months, the light is useless. I have
posted several versions of modified night lights using higher quality components.
This circuit is yet another version, which produces much more light than those other
designs. The circuit brings together two high power white LEDs made by Cree with a
compact AC to DC power supply from Bias Power.....
|
- 2 LINE
TELEPHONE LINE STATUS INDICATOR
Many home businesses use multiple phone lines. This circuit gives you a visual
indication when a line is in operation. The two AA battery cells should provide
enough power for about one year of operation. The circuit is line polarity
insensitive.
|
|
|
|
|
|
Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
|
|
|
|
2 Transistor 2 LED Flasher - Schematic only, there is no circuit
description…. [Tony van Roon's circuit] |
|
2 Transistor LED Flasher - This is a classic 2 transistor astable
multivibrator. Many other NPN small signal or switching transistors can be used,
including 2N4401, PN2222 or 2N2222 using the circuit on the left. The circuit can also
be inverted using PNP transistors…. [from Bill's Electronics Reference Library] |
|
2 Transistor LED Flasher (Bill Bowden) - This circuit will flash a bright
LED (500 mcd) as an attention getting device or fack car alarm. Component values
are not cirtical and other transistors may be…..... |
|
20mA LED Ballast
- I use this circuit for general use to power white LEDs, like a headset light I use
on my desk and a keyboard light for my computer. I built it into a tiny Radio Shack
project box (270-288), which they no longer sell. I put heat-shrink tubing around the
female output connector (RS P/N 273-1743), so that the contacts are not exposed, but
you can still plug and unplug it.....[Designed by Andrew R. Morris (added 9/05)] |
|
230V Rotating & Blinking LED - This design can be of some interest for those
wanting striking light signs, as it can drive up to three 230V lamp strings in three
operating modes. The 15V dc supply is obtained from a nominal 230/24V center tapped ac
transformer (T1) and a full wave rectifier.....(electronic design added 09/08)
|
|
24VAC Powered White LEDs - 24vac is a popular voltage. It is often
used in low voltage lighting systems and industrial controls. It is much less
dangerous than 120vac/240vac line voltages. The circuit below is one method to
efficiently power a cluster of 7 white LEDs from 24vac. It uses a classic bridge
rectifier and filter capacitor to convert the AC to DC..... [Designed by David A.
Johnson] |
|
25 Light Sequencer using Xmas Lamps - This circuit above can drive 25 small
Xmas lights. The lights operate at about 200mA and 3 volts. The supply voltage is set
to 5 volts and the 4017 counter output will drop about a volt using the 2N3053
transistors. The voltage on the emitters of the rows transistors will be about 0.7
volts less than the base so the lamp voltage will be about 3 volts. You can..... [Bill
Bowden] |
|
28 LED Clock Timer 72 LED Clock - programmable clock Timer circuit that uses
individual LEDs to indicate hours and minutes (added 4/02) |
|
|
|
|
Next LED #'s
Previous LED #'s |
|
LED: #
A B
C D - E
F - H I - K L
M - O P- R
S T
U - V W -Z |
|
|
