Whites Surf PI schematic

[Vadim18]

More info on the VCO Please ?

Just simple voltage controled oscillator with integrator (OP3_A in my circuit) and comparator (OP3_B), with square wave output - thats not my design. It has close to linear frequency swep from zero to 800 Hz, i limit upper frequency by using 3v3 zener diode at OP2_B feedback and also did that by adjusting capacitor C8. Also VCO in my circuit need some more audible than 1-20 hz start frequency, to hear weak signals but in my locations with mineralised ground i lose nothing)

[Vadim18]

Here is some of my unit fotos. Was completed in almost 4 years ago.






Op-amp VCO tests
SurfPI_VCO-test.zip

[dbanner]

Interesting VCO sound. Not a bad modification at all. I suppose with some tweaking, it can be made to work better at the lower frequencies with weaker targets. Overall, quite a good effort.

[Vadim18]

Interesting VCO sound. Not a bad modification at all. I suppose with some tweaking, it can be made to work better at the lower frequencies with weaker targets. Overall, quite a good effort.

Hi dbanner! Thanx for your comment!

Yes, vco is not bad addition and it also can produce 50% duty cycle output.
However today this addition produce more noise than clear tone, so probably i will put some RC filter to smooth control voltage.
I think also to check active clamp at SAT in the nearest future, hope it make response between big and small targets cleaner.