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Subject: Re: Constant current sources to drive LEDs on long lines

Date: 02/27/03 at 12:12 AM
Posted by: Ron Harrison
E-mail: rmaxh@yahoo.com
Message Posted:

In Reply to: Re: Constant current sources to drive LEDs on long lines posted by David Ambry on 02/26/03 at 7:37 PM:

David,

Here's the netlist for the first circuit again.

R1 vcc e2 200
V1 vcc 0 10
Q2 out c1 e2 NTE129P
Q1 c1 in e1 2N3904
R2 vcc c1 2k
R3 out e1 1k

Here's the schematic for this netlist. Transistors are listed as
Qn c b e Type

I think you can figure out the resistor netlisting.

I took out the 4th node (node 0) from the transistors in the original netlists - transistors in ICs have a 4th (substrate)

connection, and I inadvertently used that symbol to make the original schematic and netlist.

Below is an ASCII drawing of this circuit.


vcc
+---------------+
| |
| .-.
.-. | |R1
| | | |
| |R2 '-'
'-' |e2
|c1 | |
| |
|e1 ___ |
+---|___|-------+-------Out
R3
created by Andy´s ASCII-Circuit v1.22.310103 Beta www.tech-chat.de


Here is the second netlist and schematic:

R1 vcc e2 200
V1 vcc 0 10
Q2 out c1 e2 NTE129P
Q1 c1 in e1 2N3904
R2 vcc c1 4.7k
R3 0 e1 3.9k


vcc
+---------------+
| |
| .-.
.-. | |R1
| | | |
| |R2 '-'
'-' |
| | |
| |
.-. |
| |R3 Out
| |
'-'
|
GND
created by Andy´s ASCII-Circuit v1.22.310103 Beta www.tech-chat.de


I hope this helps. I agree that a voltage regulator would make things simpler. You might want a switcher if you have a lot of

LEDs to drive.

Ron


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