AVR-Chat

At 08:09 PM 10/17/2004, Daniel Boyer wrote:



>I'm working off of a schematic that I found on the web which is an
>ultrasonic rangefinder utilizing a PIC... The transmitter section has
>the PIC driving an Ultrasonic Transmiter at 40khz... The schematic shows
>one side of the transmiter connected to one pin on the PIC and the other
>side connected to another pin on the PIC.... I am doing this with a
>Tiny15; shouldn't one side of the transmitter be connected to ground and
>the other to the avr?  Do I need to use a resister or will the
>transmitter draw a low enough current?  Should I use a transistor to
>drive the transmitter?

The transmitter is basically a capacitor.
What they are doing, is bridge drive, and will potentially double the 
applied voltage.
You could go with single ended drive, at a maximum range penalty of about 
1/4 less range.