Surf PI

[golfnut]

I saw you tube of the surf pi.

I think we could freshen up the time to sense a target modding this area of the cct..


time shifted samples are judged on their amplitude, the thing is, the differential amp has large time constant caps on it so you have to do loads of samples to charge the caps - in order for it to give a big enough difference to det a target.

If each sample gate was a sample and hold you would not have to wait to take loads of sample to det the target.

If you use 2 of the attached Sample and hold ccts into a Diff amp - this would speed up the time to recognise a target

[homefire]

What would clear the sample and hold?

[Vortxrex]

What is the device between the input & c1? is that still the 4066 switch?

[golfnut]

I think the device is a 4 terminal mos switch, a 4066 mos switch is very similar - just gates the input level in.

I would say the next sample overides the previous sample. The cct is not a peak detector where the highest value stays recorded like a peak detector or rectifier / cap combination.

The signal on the input is 'gated' thru when the switch is on and 'held' while the mos switch is off.

[golfnut]

[golfnut]

Something like this.

maybe need some tweaks - but this is what I was thinking.

[DOOLEY]

hello golfnut ,

that idea / picture is like whats used on the blind squirrel by mike starcher (old radio builder) , but duplicated for 2 samples instead of just one.

this is the basic idea of my current home brew detector i am using at the moment.

2 channel / sample which can be modified to provide very basic target I.D.

[DOOLEY]

ps: do away with the R1 (10k's) after the hold caps , they don't realy serve a purpose ,
but feed each 4066 with a 2.2k ,

[Vortxrex]

Here is the "Blind Squirrel" check out the frequency programming !

http://oldradiobuilder.com/mdetsp.html

[Vortxrex]

I am thinking you could use a daughter board (connected by DIP Header) in place of the 4066, then the 4066 & LM102 w/associated circuitry are on the daughter board

[DOOLEY]

HELLO VORTXREX ,

yes pulses made by a 4536 , little expensive , but yes clever,
i opted for a simple 555 aproach , simple and yet effective,
but kept the 4538 ,well , substituted for 4098's

never heard anyone rave on about this design , but it's simple and works well , and is "non motion"