Hi

[Ruben2000]

For the coils it is very important that TX is 1mH and RX 15mH?

[Ruben2000]

Second, on its PCB and on the Lay I put two 100K resistors but in the diagram they are 10K.

[Ruben2000]

First I would like to know why you added this resistor and the connections?

[Ruben2000]

Hello Iconic good work for the contribution of the SMW.
I am just getting started on this MD and I am mounting all the components on the PCB; but I would like to ask you several questions regarding the latest publication of the PCB.

[ivconic]

Hello ivconic your Settings TX ans rx are
TX 517nf,1mh=7khz
Rx 68nf, 14.75mh=5khz
Did this correct ?
Regards

7-7.3kHz, depends on components tolerances.
But SMW will work fine from 6.5 to 8.3kHz with slight adjustments.
Yes, you got those right.

[hooby life]

Q6, BC327/40 should not get hot at all.
TX coil inductance can vary from 1mH to 2.2mH and in resistance 2.5 to 3.5 ohms.
In case of 1mH; parallel capacitor is 474+473 in parallel.
In case od 2.2mH; parallel capacitor is 224.
R12 200 ohms usually adjusted to 68-100 ohms.
R12 serves there to adjust TX amplitude, when observed on oscilloscope to be clean sinus.
Better to use fixed resistor later when adjusted clean sinus.
I can't imagine why and how Q6 can get hot; is schematic and coil specs are obeyed.
Maybe TX coil resistance is too low and applied voltage is too high?
That's common case at some people trying to "boost" it up on amplitude, hoping for better performances.
There would be no better performances that way. On contrary.

Hello ivconic your Settings TX ans rx are
TX 517nf,1mh=7khz
Rx 68nf, 14.75mh=5khz
Did this correct ?
Regards

[Carl-NC]

Q6, BC327/40 should not get hot at all.

My apologies, I was thinking PI circuits. Ivica is right, Q6 should not get hot. It probably means the oscillator is not oscillating and Q6 is just dumping DC current through the coil.

[ivconic]

Q6, BC327/40 should not get hot at all.
TX coil inductance can vary from 1mH to 2.2mH and in resistance 2.5 to 3.5 ohms.
In case of 1mH; parallel capacitor is 474+473 in parallel.
In case od 2.2mH; parallel capacitor is 224.
R12 200 ohms usually adjusted to 68-100 ohms.
R12 serves there to adjust TX amplitude, when observed on oscilloscope to be clean sinus.
Better to use fixed resistor later when adjusted clean sinus.
I can't imagine why and how Q6 can get hot; is schematic and coil specs are obeyed.
Maybe TX coil resistance is too low and applied voltage is too high?
That's common case at some people trying to "boost" it up on amplitude, hoping for better performances.
There would be no better performances that way. On contrary.

[Carl-NC]

If the LM555C is bipolar (I think it is) then the NE555 will work.
Q6 gets hot because it is the TX coil driver. The amount of hot depends on the TX frequency and pulse width. Often this transistor gets a heat sink.

[Hach]

Plugging in a chip backwards usually shorts out the power supply via the ESD diode between the VCC and VEE pins. This is unlikely to cause damage beyond the chip itself, and the power supply circuit that feeds it. It is possible, however, that the 11V got applied to the I/O pins of the 4053 so it depends on what is connected. Remove the 4053 and see if there is any excessive current draw. Check the signals up to the 4053. If everything still looks good, plug in a new one and see what happens.

Transistor Q6327, Cd4053 and 555 were corrupted
I replaced it then back to life.
I replaced Lm555 by Ne555 is it OK or not?
And why Q6327 some time getting heat?

Thanks Carl.

[Carl-NC]

Plugging in a chip backwards usually shorts out the power supply via the ESD diode between the VCC and VEE pins. This is unlikely to cause damage beyond the chip itself, and the power supply circuit that feeds it. It is possible, however, that the 11V got applied to the I/O pins of the 4053 so it depends on what is connected. Remove the 4053 and see if there is any excessive current draw. Check the signals up to the 4053. If everything still looks good, plug in a new one and see what happens.

[Hach]

It's possible the 4053 is dead, but it's also possible that the power supply feeding it is dead. Measure the power supply voltage.

Power supply voltage is 11v.
Still there is sound comes out (tik tik til) but no detection
May be I need to replace Cd4053 but I afraid more parts are corrupted.

[Carl-NC]

It's possible the 4053 is dead, but it's also possible that the power supply feeding it is dead. Measure the power supply voltage.

[Hach]

Hello everybody
By mistake I put the Cd4053 backward in dip and switched bord for one minute and back it to its correct place after that SMW stopped detect any metal. Dose that mean Cd4053 corrupt or something else.?

[MartyJ1963]

Hiya,,I'm also looking for the TX and RX frequencies. What should each frequency be? Regards, Marty.please