TX Drivers Compare

[Daves]

Hello,
How can I compare TX driver circuits and determine which is better?
Let's say there are two detectors, both of them use the same TX driver and coil size and type, how can we make a measurement and compare? What criteria should we check?

[pito]

Field Strength Meter

[Daves]

Field Strength Meter

What information will what I measure with this device give me?

[pito]

https://en.wikipedia.org/wiki/Field_strength_meter

[Daves]

https://en.wikipedia.org/wiki/Field_strength_meter

Have you used this device? Have you ever measured a detector before? If so, what kind of results did you see and which models were they?
Let's say we see a low result here, so what could be the reason for this? So, what part of the tx driver affects this?

[mwman]

Good use of an old HF vswr / field strength meter, I think it would be prudent to follow the manner radio antennas are tested.
A Faraday cage to minimise external emissions then a reference loop properly matched into a resistive load.

[pito]

This is my version of Field Strength Meter, coil on the floor under the table, 50cm to the Tx coil lying on the table connected to the oscilloscope. I'm just comparing the amplitude of different Tx.
So, what part of the tx driver affects this? = amplitude of Tx driver output.

[Daves]

This is my version of Field Strength Meter, coil on the floor under the table, 50cm to the Tx coil lying on the table connected to the oscilloscope. I'm just comparing the amplitude of different Tx.
So, what part of the tx driver affects this? = amplitude of Tx driver output.

Is it just the frequency and vpp value of the tx driver circuit we see here? We can see this with an oscilloscope, right?

Or are we seeing the actual current, frequency, vpp coming out of the tx coil here?

So, if the tx driver, which we see low value here, only increases the power of the tx driving signal, will it see a better result as vpp or will more current be required?

[pito]

We can see how much energy is coming out from Tx coil.

[Daves]

We can see how much energy is coming out from Tx coil.

If possible, could you share the values and schema of the mechanism you created?

[pito]

On picture with coil you can see small white cable, it is going to oscilloscope. The values I am reading are in range of 1Vpp.

[Daves]

On picture with coil you can see small white cable, it is going to oscilloscope. The values I am reading are in range of 1Vpp.

I meant in terms of the resistor and capacitor you connect to the coil. So can you share your strength meter circuit?

[pito]

There is nothing connected to the coil = random coil > cable > oscilloscope.
You can use, 20 cm diameter coil, 200 turns, 0.3 mm wire .

[Carl-NC]

Daves, all you need to do is wind a small pick-up coil and connect it to an oscope. Preferably trigger the oscope off the TX circuit if you can get to it. The pick-up coil doesn't matter a whole lot, a diameter of 50mm and 25 turns of magnet wire will work, more turns will improve sensitivity. Your measurements will be relative, just some peak voltage on the oscope. But it's enough to see how the field strength varies around a coil, and to compare 2 coils or 2 transmitters.

The downside is that this is a voltage-mode probe which means that TX frequency affects it so, for example, you can't directly compare 10kHz & 15kHz TX fields. To do that you need a current-mode probe, and ITMD3 will show how that is done. But for starters, just wind a coil and play with that a bit.

[Daves]

Daves, all you need to do is wind a small pick-up coil and connect it to an oscope. Preferably trigger the oscope off the TX circuit if you can get to it. The pick-up coil doesn't matter a whole lot, a diameter of 50mm and 25 turns of magnet wire will work, more turns will improve sensitivity. Your measurements will be relative, just some peak voltage on the oscope. But it's enough to see how the field strength varies around a coil, and to compare 2 coils or 2 transmitters.

The downside is that this is a voltage-mode probe which means that TX frequency affects it so, for example, you can't directly compare 10kHz & 15kHz TX fields. To do that you need a current-mode probe, and ITMD3 will show how that is done. But for starters, just wind a coil and play with that a bit.

Actually, I already use this method, but I think there is no need for this coil to learn this information. I can already see the same data through the PCB with an oscilloscope, right? I'm actually researching what I can look at differently in terms of performance criteria.