distance measuring sensor

hi, me and my friend guitar have build transmitter circuit and recevier circuit from the first circuit that is with the NAND gate ic.

we use a 74LS00N ic and a capacitor of 220pf instead of 180pf (due to non availibility). but the circuit is not working.
we attach the wires of CRO on the pins of ultrasonic transducer in transmitter to check the frequency that is generated, but there is no frequency shown by CRO.

what we should do ??

hi rahul,
i think u should see the application note (pdf file ) posted by ajay. in that try using the circuit in fi.6 which is built around the 555 timer. it is much simpler in construction. figure12 shows the actual setup u may require to build a distance meter. I would recommend that u guys first build a simple oscillator of 40kHz around the sensor preferably around the 555 timer and check the received waveform on the ultrasonic receiver. the reason why i recommend the 555 timer is that u can easily control the pulse train from the uC by disconnecting the pin4 (reset pin) of 555 and giving it directly to the uC port pin.

P.S.i have many a times found startup problems with the standard external crystal oscillators using the 7404 invertor ICs( i neded external crystal oscillators while working with z80 uP long time ago). 555 is much simpler and sure to work as the frequency stability is not that critical for ur application.

we use a 74LS00N ic and a capacitor of 220pf instead of 180pf (due to non availibility). but the circuit is not working.
we attach the wires of CRO on the pins of ultrasonic transducer in transmitter to check the frequency that is generated, but there is no frequency shown by CRO.

what we should do ??

rahuljin

I think you should do as pdi33 suggested and use the atmega 16
to generate the pulses.
If your aim is to measure distance and display on an LCD
you might as well get used to using the chips abilities.

The more circuitry you add on, the more there is to go wrong

PS
Also don't substitute a 74LS00N for a CD4011, they are very different items