On Tue, 30 Dec 2003 08:57:09 -0600,
said...
On Tue, 30 Dec 2003 12:36:45 GMT, Active8
,invalid wrote:


Rough guess...



---+------------------+
| |
| 10 |
| ___ |/
+---|___|---+----|
| |
| |
- |
5.6 500mW ^ +---------
|
-------------+----------------

---
Closer guess:

Ib ~ Ie/ß = 200mA/100 = 2mA

IZt = 20mA

R = (Vin-VZ)/(IZt+Ib) = 0.4V/0.022A = 18.18...R ~ 20R


Ok, I incorrectly guessed Beta (Chaos Master told me how to get
special characters and it doesn't work here) of 200 and set Iz at
40mA (a waste) to get the 500mW zener to operate at about half it's
rating. I know, I only needed 10mA if Ib really were 10mA.

--
Best Regards,
Mike