Crumar Musical Instruments User Group.

neurokrash wrote:

>I read a data sheets on the 7805 and 7812 from my P1108 board, and
>didn't see any indication that these were intended to output anything
>outside of 12v or 15v.  Can you verify that 17v is okay, or could
>these parts be the problem?
>
>  
>

Yup, i also don\ufffdt knwo any 78xx part which outputs +17 Volts. The 
-incoming- Voltage (left pin) should be approx. 17 Volts on a 7815 for 
example, where its output voltage must be -flat- +15 Volts. A 7812 which 
gets a input voltage of +17 Volts is in my opinion too much; i even 
don\ufffdt know a constellation where 0V is connected on the left pin and VCC 
on the middle. Buit, if the schematics tell te same, -then-. it must be 
correct.

 I had a while ago also some trouble with a simple Microcontroller, 
where its VCC was connected to a 7805. I simply forgot to lower the 
input Voltage of the 7805 and it gots straight +12 Volts. The 7805 
didn\ufffdt liked that and produced a output voltage of over +7 Volts, 1.5 
Volts over the maximum current of the Microcontroller, which got death 
after approx. 20 seconds later caused by overheating. The 78XX series 
automatically turns off when overheating and switch back on after a 
cooling time, but often much too late.

Greetings
Stef