coil inductance for this p.i. specs

[homebuilt_ pi]

good day,

this is the specs of the homebuilt p.i. that i purchased and i want to make some coil...any help please....with this info, what is the appropriate value for inductance....also....what is the difference in performance on mono coil against dual coil (tx rx)..last, is it possible to make this dual coil for mono coil without altering internal circuitry?..thanks in advance

pulse width : 1 / 680 hz = 1.470 mS (milli seconds)
pulse frequency : 680 hz
pulse delay : 1.449 mS (mill seconds)

sample pulse or
pulse window : 21.3128 uS (micro seconds

[Carl-NC]

First, the specs don't make sense... if frequency is 680 Hz then the duty cycle is 1/680 = 1.47ms. The pulse width (of the transmit pulse) should be substantially less. And the pulse delay (sample delay?) should be 15-30us.

You probably have a fair amount of latitude in making a coil that will work. I would start with 300uH. Whether you can use a dual coil depends entirely on the circuit design; most likely you will have to modify it.

- Carl

[homebuilt_pi]

coil

thanks carl for the prompt reply,....actually i dont understand much the specs that was emailed to me by the maker of that p.i....i just posted it anyway........so i begin in 300uH then...

[homebuilt_pi]

beeps adjustments

my pi is analog.....i have this question long time ago since i bought this unit.....i have a lot of trouble adjusting the beeps of my pi, very much hard if using a big 1m coil......i wouldnt notice if it is hitting any metal since i cannot immediately move from one area to another to rule out the signal, if it is hitting metal or just going fast as i move, until you adjust it to low again......are analog pi needs be adjusted constantly while you are scanning?...i cant rely on the meter, since the needle moves when i move......so changes in beeps are very hard to notice....i have seen other pi that is silent, and makes a solid beep sound (not increasing beep-beeps) after hitting some metal.....can this be done to my pi? or i need to trade-in for a digital p.i.....any comment please....thanks