i was going to set a 555 timer up on its own first get th 40khz output then look at the transmitter receiver, but the output of the 555 is only 20mv and im not sure why ill probably use the latest one to go of
cheers
To check if your 555 is running, add a 10uF cap across the 0.01uF, connect a 470R resistor from pin #3 to an LED to 0V, it should flash. EDIT:
make that a 100uF not a 10uF
BTW: the 555 is running at 35KHz in your original circuit.
this is really killing me now as i get nothing lol, i still think its the 555 because it gets really hot but i cant test untill tuesday when i can use a scope
any ovious things guys?
ive bridged the bottom gap for voltage and still nothing btw
any advisae will be appreciated cheers for sticking with it
Why are your resistors HUGE? 1W? I use 1/4W resistors.
EVERY electronic circuit and sometimes every IC should have a power supply bypass capacitor. 0.1uF is good. It prevents an IC from oscillating at a high frequency that makes it hot. Your circuit is missing one or two. It should be VERY close to the power supply pins of the IC.
All the 555 circuits in this thread use feedback from pin 3 to pins 2 and 6 so the output is a squarewave. Your 555 circuit is different and uses feedback from pin 7 which might produce narrow pulses instead of a squarewave.
What is your supply voltage and what is the part number of your 555 so we can see if it is a Cmos (max supply about 12V) or ordinary 555 (max supply about 15V)?
A power supply bypass capacitor is recommended in the datasheet of the 555. Connect a 0.1uF ceramic capacitor with short leads between pin 8 (Vcc) and pin 1 (Gnd) as close to the pins as is possible.
The datasheet shows a 0.01uF (10,000pF) capacitor from pin 5 to pin 1 (Gnd).
Measure the resistance of the Tx transducer (disconnected from the circuit). If it is a piezo one then its resistance should be infinity.