BIPOLAR ALTERNATIVE TO H BRIDGE

[JoyJo]

Do you mean that the connection of the TX coil is the same as in a full H-bridge? And connecting the TX cactus to the device unit via a differential cable: two strands twisted together?

[moodz]

You could isolate it by two caps but do you want multi frequency?

[JoyJo]

It is interesting to be able to work on a single frequency, but so that you can also get a multi-frequency mode.

[Haydar]

Is this design for a PI system or an IB system? Could you explain how it works without a damping resistor? I don’t understand. Also, you clipped the signal going to the RX stage at 0.7 V using a 1N4148. What would happen if we raise this 0.7 V threshold?

[Carl-NC]

Technically it is a form of PI but requires an IB coil. It transfers the magnetic field energy onto the coil capacitance as an electric field energy, then immediately reverses the process to the opposite direction. No damping resistor is needed because there is no free-running oscillation to dampen. That is, the coil is always driven and never left open.

The diode is just a protection device to prevent unwanted spikes (during the transitions) from zapping the preamp. If you could make a perfect IB coil then they would not be needed.