 |
Search Sci.Electronics.Basics |
|
|
|
|
|
|
 |
|
|
Sci.Electronics.Basics -> transistor base input
There are 21 messages in this thread.
You are currently looking at messages 20 to 21.
|
Author: lerameurDate: 21:52 04-05-08
|
|
On May 4, 4:55 pm, Randy Day <randy....@shaw.cax> wrote:
> lerameur wrote:
>
> > On May 2, 12:08 pm, gearhead <nos...@billburg.com> wrote:
> > > On May 1, 2:42 pm, John Popelish <jpopel...@rica.net> wrote:
>
> > > > gearhead wrote:
> > > > > On Apr 30, 2:55 pm, Randy Day <randy....@shaw.cax> wrote:
> > > > >> Just use your micro as a digital input; no analog required.
>
> > > > >> 6-9vdc in --10K-----+------ micro
> > > > >> |
> > > > >> /\ 5v zener diode
> > > > >> |
> > > > >> Gnd
>
> > The output is DC, depends on the batteries voltage. But it is usually
> > 6.4v.
> > Well I tried the circuit with the zener diode. I get 5v at the output.
> > But as soon as I place the microcontroller input pin, that voltage
> > just sink to 1.4v and the controller do not read it. If I put the
> > input pin directly on the output of the 7805 regulator (5v) then it
> > reads it as 5v. I used a 150ohm resistor afterwards, that did not
> > work. why is that ?
>
> As an experiment:
> put the 10k resistor back in, and connect the
> input end to the +5 supply for the micro.
>
> Measure the voltage with and without the zener
> in the circuit.
>
> If the voltage stays at 1.4v, you've probably
> got:
>
> a) your input pin is actually programmed as an output pin
> b) your input pin is actually programmed as something other
> than a digital input (analog, clock in, etc).
> c) a fried input to your micro.
>
> A working digital input is said to be 'tied high'
> with a 10k resistor; the voltage should be near +5.
> If your voltage is 1.4 without the zener, the problem
> is in the micro.
>
> Can you hook a 10k to another input pin on the
> device to compare?
crap, my pin was set to output...
thanks
|
|
|
|
|
|
|
|
|
Contact | Electronic Portal
|
|
|
