- Tue Jan 19, 2010 7:01 am
#91174
I've finally managed to get my ultrasonic sensor circuit to work and detect a reflection, but only using the indoor transducers (not the ones I need to use), but the outdoor ones would only have a reflection of about 100mV after 7,500x amplification driven at 5V (see original post and scope here viewtopic.php?t=18817&start=15).
I presume that the outdoor sensors are a higher voltage rating or something and need driving at a higher voltage (could it also be something to do with 30mA current from PIC not being enough?). Unfortunately I have no specs on them but do know they are 40kHz and are xceivers not just transmitters.
My main questions are firstly how can I boost my 5V frequency to 20V or at least higher than 5V, with the smallest (size) components and only having a 5V supply line feed (so cant use a 12V line and a transistor for example).
Secondly, once I drive the transducer at a higher voltage, my amplifier is connected to one of the pins so would see that higher voltage also and damage it, so could I just use a zener diode clamp or would that not react fast enough?
I presume that the outdoor sensors are a higher voltage rating or something and need driving at a higher voltage (could it also be something to do with 30mA current from PIC not being enough?). Unfortunately I have no specs on them but do know they are 40kHz and are xceivers not just transmitters.
My main questions are firstly how can I boost my 5V frequency to 20V or at least higher than 5V, with the smallest (size) components and only having a 5V supply line feed (so cant use a 12V line and a transistor for example).
Secondly, once I drive the transducer at a higher voltage, my amplifier is connected to one of the pins so would see that higher voltage also and damage it, so could I just use a zener diode clamp or would that not react fast enough?