TM 808 White's

[pito]

A can be replaced by stm32f103, B by 3x18650 battery.

[berreizeta]

Coil perimeter 123.5cm (26.5*3.14+20+20) = a circle of 40cm diameter

Fixed op amp bias.


3V at 33078 out (pin 1), I think the coils should be 66.5cn from each other

[pito]

On first pic, your 85 cm is 35 in my case, pic #2 this is how I am checking Tx power, only coil .

[pito]

Coil perimeter 123.5cm (26.5*3.14+20+20) = a circle of 40cm diameter

Fixed op amp bias.


3V at 33078 out (pin 1), I think the coils should be 66.5cn from each other

You need to minimize this to millivolts , using aragment as on post #195, that is channel 1 oscilloscope to channel 2 connect testing coil and switch oscilloscope to XY mode, you should see respond to a can of coca cola from about 1 m away.

[berreizeta]

A solution with 420Khz =



B:
DC Step up Hw-432, 7-12v to 16V

DC Step down HW-187, 7-12v to 6V

Voltage divisor LM324 on TM808 PCB.

One question: Is the use of 6V for the tip31c due to consumption or power level?

[berreizeta]

At what point should the coils be placed, at the maximum or minimum signal on the oscilloscope ?

Coils at 66cm , signal direct from RX coil



I don't know how to upload a video here...

[pito]

A solution with 420Khz =



B:
DC Step up Hw-432, 7-12v to 16V

DC Step down HW-187, 7-12v to 6V

Voltage divisor LM324 on TM808 PCB.

One question: Is the use of 6V for the tip31c due to consumption or power level?

TIP331 is powered directly from batteries to separate it from rest of circuit, I believed that connector P7 is for speaker - it is very strange design.

[pito]

Testing video inserting

You have to place video on youtube then paste the link to it in box insert Video, next to insert image box,

[pito]

Rx coil should be with resonant capacitors, and moving Tx coil you need minimum at RX coil. On your picture is hard to see how coils are placed.

[berreizeta]

Testing coils :

https://youtube.com/shorts/7IwzeES0-Zs?feature=share

[berreizeta]

Adjust the coils to the minimum signal, without losing the frequency :

https://youtu.be/E_VlChTRuSI

[pito]

Adjust the coils to the minimum signal, without losing the frequency :

https://youtu.be/E_VlChTRuSI

and what is your minimum in volts?

[pito]

Adjust the coils to the minimum signal, without losing the frequency :

https://youtu.be/E_VlChTRuSI

Sensitivity is very low, that can be to low transmitter power, or Rx not in rezonanse. Put Rx and Tx 10m or 5m apart, adjust for max voltage on RX , at 10m you need about 10 mV.

Maybe there is someone who have access to TM808 an can measure emitted power of Tx for comparison ?

[berreizeta]

Without losing the frequency: 30mV,

if I lower the signal further the frequency goes away...

[berreizeta]

I'm going to make a new RX toroid, the one I use has too much resistance 7.8ohm

I will try to get 2.1ohm and 17.5mH for RX