Carl
06-25-1999, 07:40 PM
>There is a PI design on the market now - The VibraProbe. The selling points for it are:
>- It vibrates when near metal, which makes it good for use with headphones (for the main detector), or near surf - so that you need not strain to hear a beep.
I've seen the little vibrator motors for about $2 from Circuit Specialists. I plan to get a couple next time they are available
>Carl - You mentioned a VCO design - is there a reference to this type you could point me towards (no pun intended!)?
The VCO design uses only one oscillator instead of the traditional two. If a target attempts to change the oscillator frequency, a detector feeds back a voltage, usually to a varactor, to re-stabilize the frequency. Thus the output is a voltage that indicates whether a target is present. I will try to get more info and maybe post a circuit.
- Carl
>- It vibrates when near metal, which makes it good for use with headphones (for the main detector), or near surf - so that you need not strain to hear a beep.
I've seen the little vibrator motors for about $2 from Circuit Specialists. I plan to get a couple next time they are available
>Carl - You mentioned a VCO design - is there a reference to this type you could point me towards (no pun intended!)?
The VCO design uses only one oscillator instead of the traditional two. If a target attempts to change the oscillator frequency, a detector feeds back a voltage, usually to a varactor, to re-stabilize the frequency. Thus the output is a voltage that indicates whether a target is present. I will try to get more info and maybe post a circuit.
- Carl