From: "Brill Pappin"
Subject: Re: Connecting a PC-speaker to a PIC cpu
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Fri, 15 Nov 2002 01:50:21 GMT
NNTP-Posting-Date: Thu, 14 Nov 2002 20:50:21 EST
Likely the output from the pic is too high for the amp...
your sign wave should likely be around the 1V range... try a cap in
series... and maybe a resistor to ground (before the cap) to cut out some of
the signal from the uC.
- Brill Pappin
"Henrik" wrote in message
> I am trying to connect a PC Speaker (0.5W, 8Ohm) to a PIC cpu (16f877). (I
> am not sure about the Watt of the speaker, I do not got it in front of me
> the moment)
> I am using PWM modulation in the PIC to achieve a sinus wave. The output
> a flawless sinus from the RB1 port (measured with a oscilloscope). But
> I connect the PC speaker I get no sound. This, I assume is because the PIC
> cpu generates to low current(?). Anyone got a suggestion on a circuit that
> can use so I get my sinus-wave-sound? I've tried using a LM386 effect
> amplifier, using the circuit for a gain of 50, on the data page. But the
> signal out from the amplifier doesn't look to good.
> * Should I have a capacitance between the input of the amplifier and the
> * Is there a easier way of using the PC speaker?
> Any help welcome.
> Cheers, Henrik