Stuart real schematic

[homefire]

You was provided with the corrections. U1 Pins 12, 13 need to be connected NOT as the documents PCB is provided. The Schematic in the document it was said is correct so your transistors need to be oriented as the same. Don't use the Layout Diagram for the Transistor as it was stated they or some are in Error.

[homefire]

Back in the 70-80's Magazine projects like this were notorious for omitted or flat out wrong information. I think most was on purpose to get you to buy more magazines for the follow up articles . 95% of the time there would be a follow up clarifying some deficiency of some sorts. LOL

[dbanner]

Yes you are right homefire, many projects from those old magazines contained errors, maybe not on purpose but because of a lack of fact checking and quality controls and proper oversight and supervision. But i think they were nifty little projects nonetheless. Wish I'd kept those old magazines, unfortunately I threw them all out years ago.

[Nadhir]

then why people say it's working I made the project with corrections but beeps without any changing in frequency near or far from metal I used 24 rounds c oil of 0.4 mm tick wire
is the circuit sense the changing risistance of the coil or something else
if it's resistance I can try many resistance with differente values and see if any change in freaquency appear
any sujests are very welcome

[dbanner]

DID you Use 32KHZ oscillator(very important) or better yet 40KHZ Oscillator crystal. 25KHZ may be too low. Also did you use LM318 Hi speed op amp? Check your power supply. Are you getting 18volts? Post picture of your circuit board top and bottom.

[Toros]

Can anyone explain how this generator works? If you use 32kHz crystal instead of 40, should you change something in the generator scheme to get it running?

[waltr]

Can anyone explain how this generator works? If you use 32kHz crystal instead of 40, should you change something in the generator scheme to get it running?

No, it is a Pulse Induction detector so exact frequencies is NOT critical.

READ up on PI detectors.

[cavalry]

No, it is a Pulse Induction detector so exact frequencies is NOT critical. READ up on PI detectors.

I built this years ago and I'm just getting back into it...Of course the timing is important, even in a PI because this determines your sample period.