Time is running out

Time is running out!

Before I walk away from DIY ultrasonic sensors I thought I better test the transmitter and LM567 tone decoder receiver.

Here is the transmit pulse on the transistor collector:

Pretty untidy! Something is going on as the base pulses are clean?

Here is a transient simulation to an 8 pulse sequence:

So it is working properly!

The ringing during the pulses is part of the network matching behavour.

The post pulse ringing (after 300 us) is due to the ring of the choke (changing the inductor value changes the ringing frequency).

Here is the sensor voltage:

Okay there seems to be sub-harmonic ringing that matches the choke ringing.

But at least the voltages are nearly 20v pp.

Damping the transmitter sensor with a 1k resistor helps a little:

and

On the receiver side I am picking up signals but very erratic:

The receive sensor (off the transistor collector):

The transmit and receive signal basically overlap (lots of ringing).

After damping with a 4k7 resistor:

Better but really still pretty useless.

There is a lot of work required to get these senors working properly!

Scanning Sonar

It seems like the scanning sonar that basically worked before (but not perfectly) is going to be the fastest route to getting the Dalek finished.

So tomorrow I will dig up the hardware and see if I can get it working again.

AlanX