need mfd

[UltraLRL]

AVR DDS signal generator V2.0

http://www.electronics-lab.com/proje...ion-generator/

http://www.scienceprog.com/avr-dds-s...generator-v20/

Main AVR DDS V2.0 signal generator features:

Simple circuit with easily accessible and cheap components;
Single sided PCB;
In box power supply with external AC plug;
Dedicated high speed (HS) signal output up to 8MHz;
DDS signal with variable amplitude and offset;
DDS signals: sine, square, saw, rev saw, triangle, ECG and noise.
2×16 LCD menu;
Intuitive 5 button keypad.
Frequency adjusting steps: 1, 10, 100, 1000, 10000Hz;
Restoring last configuration after power up.

[UltraLRL]

AVR DDS signal generator V2.0 Source

source code
EagleCAD schematic and PCB
Proteus simulation files

[pigeon]

It turns out this TDA7294 amplifier is even more interesting than I thought.
Aside from being a very low distortion high power amplifier, it runs on a dual power supply that the signal generator IC can share with it.
This means you can use the two 12v batteries like Michael has in his Bulgarian LRL to run both the TDA7294 power amp and the signal generator.
The output from this amp will be higher because of it's 24 volt supply instead of the 12v that the signal generator is using above.
But this is not a problem, the 8038 signal generator is good for up to 30 volts each side of the supply.
So we can plug it into the same supply and send the signal to the TDA7294 all on the same board if we want.
This seems quite convenient for MFD builders.

This amplifier is intended to drive typical speakers from 4-8 ohms. Since the ground usually has much higher impedance, We cannot expect to put the full 100 watts of power into the ground.
But since it can handle up to 100 watts, it seems a good candidate for a step-up transformer to increase the voltage at the probes to get more power into the ground.
Of course, power transistors could do this too. The main difference is this IC is able to maintain a very clean signal without distorting it at power levels, and it is on a single IC.
When we start sending more power out, we can expect the amplifier to heat up, so we need a heat sink that will carry the heat away.
The image below shows a typical heat sink used on an audio amplifier.
But this could be made smaller, especially if you include a fan to circulate air through the fins, similar to how computer fans work.

Because this IC matches up so well to the 8038 signal generator, I show some concepts of how you could hook it up below.
This is not a circuit I tested, but I think it may work if I didn't get any mistakes in the connections.

In the circuit you can see I changed the two capacitors that set the frequency for the 8038 to a bank of 6 capacitors with a rotary switch to select which frequency you want.
You can fill in any capacitor values for your favorite frequencies.
There is also an option to make adjustments to the frequency at pin 4 on the 8038, or you can leave it in the original design.
You can also see where the transformer goes.
You can choose the transformer type depending on the soil conditions.
I think you will have a wide range of soil impedance depending on ground mineralization and how wet the soil is.
For this reason, I doubt any one transformer would be suitable for all soil.
But at least you have some control at the power knob.
Another option would be an adjustable auto-transformer that you can change to suit the soil.
But don't forget the batteries.
When you put out more power, you need bigger batteries.

Keep in mind that Michael's Bulgarian MFD locator uses this same amplifier, but he was able to detect nothing ever, even though he could measure the signal in the ground up to 2 meters distance.
And that is exactly what I think you will detect with this MFD detector... Nothing.
If you think I am wrong and this circuit really can locate treasure, prove me wrong.


Best wishes, J_P

hi friend

have you pcb for this

thank you