On 17.7.2012 9:16, IVP wrote:
> Djula,
>
> I've breadboarded the 2nd of your 2 circuits, with 10.00V from a
> PSU and a 78L05 to derive 5V. I wouldn't be happy connecting
> a PIC. Vdd and OSC1 are too high. Here are my measurements
> at the pot's extremes
>
> 78L05 o/p CCW 6.43V CW 5.00V
> OSC1 i/p CCW 7.21V CW 9.59V
>
> Joe
>

This is normal.

Without the PIC there is no current draw from 78L05 and its output gets=20
pulled high to 10V. You can load the 78L05 output with 1k resistor for=20
now and later remove it when you have the rest of the circuit drawing=20
some current.

Without the PIC the PIC part of the OSC1 circuit is missing, the 22pF=20
gets charged to maximum voltage and never discharged. Normally, the PIC=20
should discharge it when the voltage reaches 90% Vdd (4.5V) and the OSC1=20
will never see any higher voltage. This may be a problem if the PIC=20
sleeps halting the RC oscillator circuit, in that case you would have to=20
add a protection diode which may interfere with the OSC1 frequency. You=20
can test it first without the protection diode and add it later if the=20
circuit seems to work.

Put the PIC in, why don't you trust random strangers you met on the=20
internet?

Djula
--=20
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