Mod TX of Coinmaster, TM808, Eagle

[pebe]

Pebe, I use one term expressing the removal of parasitic modulation. If you do not like "dismodulation", then offer some other.

It's not that I dislike the word 'dismodulation'. I can't understand it because there is no such word in the English language.

When a carrier wave is amplitude modulated by passing it through a nonlinear device with the modulating signal, then sidebands are produced. To retrieve the modulation signal again the signal is 'demodulated'.

But your application of 'dismodulation' seems to imply that the TX wave has had its amplitude varied by some low frequency in the region 0.6 to 6Hz, and you want to get rid of that low frequency component. So why not call the procedure 'amplitude clamping' ?

As I cannot find a definition of 'parasitic modulation' anywhere I assume you mean amplitude modulation.

[mikebg]

PARASITIC MODULATOR

Peter,
Parasitic modulation means that it is caused by a parasite that absorbs energy from your oscillator. In our case, the parasite is ground or salt water. The closer you are to this parasite, the more power it consumes and the amplitude of oscillation decreases. Both side bands from 0.1Hz to 6Hz are formed due to the change in amplitude, without using non-linear process.
Here is the circuit of a device to cause parasitic modulation, which we use to measure effect of dismodulation and to adjust PID controller for stability and minimum settling time.

[pebe]

Peter,
Parasitic modulation means that it is caused by a parasite that absorbs energy from your oscillator. In our case, the parasite is ground or salt water. The closer you are to this parasite, the more power it consumes and the amplitude of oscillation decreases.

Caused by a parasite!!!! You call it parasitic modulation? Any engineer would call it 'loading' of the source.

Both side bands from 0.1Hz to 6Hz are formed due to the change in amplitude, without using non-linear process.

You mean you have sidebands 0.2Hz apart at Ftx - 0.1Hz and Ftx + 0.1Hz ?

How do you measure them? On second thoughts, don't bother!

[mikebg]

Pebe,
(R)EMI group is abbreviation of “Rediscovering, reinventing, revision, redesign and rename of Electromagnetic induction”. Our hobby is design of TXs, RXs and antennas for QRP amateur radio.
We can design very efficient TXs and extremely sensitive RXs, but for ham radio, not for metal detectors. The combination of TX and RX with an EMI sensor for MD is problem. We published a series of postings in Carl’s forum relative to frequency response of targets and results obtained by SPICE simulation of sensing network.
A metal detector consists of TX, RX and an antenna named EMI sensor or “Coil”. Carl Moreland described one difference between our antennas and EMI sensors for MD. The other difference arises when EMI sensor moves near to ground. This changes antenna impedance.
The answer of your question is in the attached figure:

[mikebg]

A visual explanation:

[mikebg]

Another visual explanation:

[derick]

Anybody tried this modification?It is possible for XLT?