AVR-Chat

I think the problem is there are not enough current to 
drive the relay. As far as i know, a microcontroller i/o 
pin should not drive (source/sink) too much current. Maybe 
you should use a transistor as a switch to drive the 
relay, and control that transistor using your i/o pin. You 
can use an NPN transistor of any kind, connect the 
collector to the resistor of your circuit(R6). Release the 
connection from R6 to your AVR. Connect the emitter of the 
transistor to ground. Then connect your i/o pin to the 
basis of the transistor using a resistor. Maybe 4k7 should 
be fine.

Hope this helps.
Irfan.

On Thu, 12 Aug 2004 02:07:55 -0000
  "kc9dag" <dpboyer@dpicts.com> wrote:
> I have designed a circuit that works fine when I run it 
>on the 
> STK500, but when I tried to move the circuit to its own 
>board (this 
> is the first time I have done an avr w/o using the 
>STK500) it does 
> not work.  I was wondering if someone would mind looking 
>at the 
> schematic 
>(http://www.dpicts.com/Tiny15L-LaserDetector.jpg) and 
> telling me what I am doing wrong?  The circuit basicly 
>waits for a 
> laser beam to be broken (detected by the photodiode) and 
>then 
> activates a relay in a set time pattern.  When I try the 
>soldered 
> circuit, the relay never activates regardless of the 
>laser (again it 
> worked fine when it was hooked up to the stk500, only 
>using an led 
> instead of the relay.)
> Thanks,
> Daniel
> KC9DAG
> 
> 
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