BIPOLAR ALTERNATIVE TO H BRIDGE - GENERATING SINE WAVEFORMS - HALF / SINGLE & FULL

[Carl-NC]

This is something I played with extensively at White's. You can also do multifrequency half-sine:



This requires a little more complicated TX circuit. I had this working on the bench.

[Dean Sarelius]

Hi Moodz,
I am just looking into the different aspects of bi-polar switching before trying some different simualtions. Have you expermented with any dual frequency bi-polar designs as yet or do you think that a single frequency front end should suffice..?

[moodz]

Basically we can add a suitable capacitor C2 in series with the coil on the BATHB ( Bipolar Alternative To H Bridge )




Like so to get ....From CC bipolar pulses to half sine bipolar pulses ...


then we can modify the pulse timing ( so that a negative half sine pulse is immediately followed by a positive half sine pulse ) driving the BATHB ... to generate single sine pulses at any spacing we like



removing the "off periods " in the timing pulses we have the continuous sine wave form.



... it may be desirable to remove coil ringing during "OFF" periods ...

so we add a simple damping network ... C7 and R5



and voila ... no ringing. LOL





1 .What all of this means is that by arranging for the capacitor to be switched in/out of series with the coil the detector transmit coil can be made to transmit square or sine pulses or parts thereof thus providing maximum versatility.

2. The waveform can be varied dynamically to do this in real time by switching capacitors / inductance and timings thus adding further utility.




moodz

[moodz]

Sometimes a half sine / single sine cycle or continuous sine current pulse in the transmit coil is required. Here are some methods of doing that.