Simplest PI detector possible?

[raff33]

Many people on the Russian forum make this circuit. It works immediately and without problems. If there are no errors in the assembly.
25mm copper disk detects a distance of 20-25cm.

Hi eddy71,
can this circuit work with large coil 1m*1m ?
ragards

[Eddy71]

I not try.

On one of the Russian forums people say they work well with a large coil.

[6666]

Thomas please keep us updated on your project when your parts arrive thanks.

[Thomas]

Thomas please keep us updated on your project when your parts arrive thanks.

This is what I'm starting with

from this any suggestions ?

[satdaveuk]

How much more basic can you really get than the surf or the Barracuda, there proven and every aspect from battery to the front end has been covered over and over again.
The machines work and have been built with working results more than any designs on here to date.
If you use correct components on your build together with correct assembly they are fool proof.
Silver dog even does kits for the novis with everything marked so you cant go wrong.
Regards

[Eddy71]

Some change in shematic. Distance about 40cm nj 1 uero coin. R7 - 1W, D1-D2 - 1N4148.

[brucester]

I just built this on my breadboard.

I used a TL072 amp and a standard npn transistor for T2

Turned it on, nada :P

Going to bed, will debug it in the morning

[Thomas]

How much more basic can you really get than the surf or the Barracuda

My plan is to get it down to 1 Chip.

[6666]

I used a TL072 amp and a standard npn transistor for T2

What did you use for T2 ?

Did you use solder-less breadboard ?

[6666]

Distance about 40cm nj 1 uero coin

Eddy thanks for information, do you know what coil they were useing ?
Thanks

[6666]

Some happy snaps
measured 140 PPS

1st 555 pin 3 50uS/CM

2nd slightly faster time base.

[johnandles]

I just built this on my breadboard.

I used a TL072 amp and a standard npn transistor for T2

Turned it on, nada :P


Going to bed, will debug it in the morning

Looks like you may have reversed the invert, non invert inputs for the TL072 pins 2,3.
If you followed your post schematic #34
C3 should be going to pin 2 (inverting input)

[brucester]

I used a solderless breadboard.

Checked my TL07, the -/+ inputs for op1 and op2 are correct.

Leason learned, I need an oscilloscope :P

Will rebuild in by transfering each part to a new bread board, testing each output before moving on to next section.

Will use this mosfet this time: http://www.freetronics.com/products/...e#.UP4hDSdwdEw

[Eddy71]

Eddy thanks for information, do you know what coil they were useing ?
Thanks

People's use coil for SurfMasterPI.

[brucester]

Ok, spent some more time with the Russian wonder.

Heres a little pic of her here:



When i flick the on switch, my power led goes on, and i enjoy the sound of silence.

Thought i better double check a few things.

I have it wired up so VCC+ is positive rail and pin 8 (VCC-) goes to ground.

Is that right? Or does it invert the power?

If i switch VCC+ to ground and VCC- to positive the op amp gets really hot.

Triple checked the wiring, it all seems correct. All my transistors seem to work, no power through the speaker one though obviously as i cant hear anything, the 555 timer works, keeps an led flickering if i hook one up to pin 3.

I have noticed R5 gets quite warm, but not hot.

I have trimmed the trimmer back and forth, still nothing.

Out of ideas.