TM 808 White's

[pito]

The best prog .: Sprint-Layout 6.0

Indicate me an email and I will send it to you

Thanks
I am trying figure out how to put all together.

[pito]

Just Tx and Rx tuned coil connected to oscilloscope, reaction noted at 80cm, with amplifier should be over 1m. I not happy with power of Tx, should be 2x more, probably transistor not good as in original.

[pito]

I sent you a private message with your email address

[berreizeta]

The best prog .: Sprint-Layout 6.0

Indicate me an email and I will send it to you

[pito]

Beautiful, and which program you are using ?
I am using ExpressPCB but there is no Gerber option.

Here is the small PCB,I need it in Gerber.
.

[berreizeta]

Ordered tm808 board to JLCPCB :

[pito]

If your videos are respond to my post # 227 it is not what I meant, I was talking about mentioned by you to small margen 10 hz.

Checking coil tuning at 6,533 Hz = you don't need exact this number, just put 1 yellow capacitor with standard capacity close to 600 nF which is 680 nF in Tx then tune receiver to Tx frequency.
Tx frequency can be different what you have now but this is not important.

[berreizeta]

Checking coil tuning at 6,533 Hz

RX :

https://www.youtube.com/watch?v=SIcBVaiZtHw

TX :

https://www.youtube.com/watch?v=en1JN9i5iqQ

[ivconic]

https://www.geotech1.com/forums/forum/technology/coils/16950-tf-900_tm800/page10

[pito]

Use the coil arrangement as in post #197, add a 10nF or 100nF capacitor in parallel to the coil, do it first for Tx then for Rx, adjust for the max voltage in Rx, if adding a capacitor is causing voltage decreasing coils are in rezonanse or capacitor is to big.

10Hz,
if changing frequency by 10Hz is effecting amplitude in Rx that is not good, it will cause instability of the device, 100Hz or more is ok.

[berreizeta]

The #215 calculator is theoretical and is used to know approximately how much capacitor you will need.





I adjust the coils with the oscillator and a function generator looking for the maximum signal,

then I do the fine adjustment with the Visual Analyzer program and function generator :





I will be with a margin of approximately 10 Hz, I don't know how to tune the coil closer....

[pito]

Interferences mostly come from wires in the wall, frequency( 6.5kHz ); +/- 15% will not effect the sensitivity of detector as long as coils are resonance tuned.
Did you tune the coils or you rely on a calculator like in post #215?

[berreizeta]

Yes, that is 50Hz interference since I have the house's electrical panel in that place.
Anyway it is just a test of the circuit's operation.

I wanted to test the frequency with the 420Khz xtal, freq. real 418Khz approx, -> 6,533 in output, also the change to the CD4040 and the output of Q1 to the TX coil, and this seems to work perfectly.

I'm going to order the PCB and when it is assembled with the components, then it will be time to make the final coils and more tests....

De todas las versiones del tm808 que tengo hechas, this will be the board that I have decided to make:

[pito]

You need a larger piece of plywood with a post as in post #195 so the Tx coil can fully lie on it, attach the Rx coil to the post with hot glue, metal bracket and screws can also be used, then adjust the Tx position for the minimum signal in Rx, fasten the Tx add U5 and see what sensitivity you can achieve.

Put Rx,Tx on stool or coffee table.

[Skippy]

I know what harmonics are. I wasn't commenting on his actual scope traces, I was commenting on what other signals can be present, in addition to the fundamental sine-wave. So he knows that trying to eliminate all RX signals will be difficult.