Page 1 of 1
3.3v zener instead of 3.6v zener
Posted: Thu Oct 09, 2008 3:21 am
by shoujin
okay i need some information about this matter, everytime i saw the example project all the zener used is 3.6v, my question is simple is it possible to use 3.3v zener instead of 3.6v zener?
Posted: Thu Oct 09, 2008 9:19 am
by Grendel
Worked for me using a Mega8, didn't work w/ a Tiny461. Turned out the I/O pin threshold voltages are different and I had to use 3.6V w/ the Tiny (3.6 worked w/ the Mega as well). If you want to play it save use 3.6V, <= 500mW.
Posted: Thu Oct 09, 2008 4:54 pm
by christian
Someone also suggested a green and an orange LED in series. The forward voltage should be pretty close to 3.3 V.
Since LEDs can differ depending on efficiency etc, measure the voltage before you use them.
Posted: Fri Oct 10, 2008 2:15 am
by shoujin
i see, anyway i risked my avr (tiny2313) yasterday with a pair 3.3v zener ( i use BZX55/C3V3 ) it worked, however i should lower the series resistor to 47, if i use 68 it won't work though. So is this okay to do this? i checked the voltage on d+ and d- with osciloscope it swinging around 3.4v - 0v is this okay?
Posted: Fri Oct 10, 2008 2:57 am
by Grendel
Sounds good to me
Posted: Fri Oct 10, 2008 5:31 pm
by christian
Yes, looks OK. But please also check the idle voltage on D-. It should be above ~ 3 V.