Probe PCB from Silverdog

[Dixix]

I'll revise my PCP layout again thoroughly. I think the problem is with the pin assignment of the IC 3 I want to like this project fit in this box (ABS Case 130x40x23mm). At the moment I'm waiting for the 5k multi-turn preset from electronics suppliers.

[WM6]

I'm not sure how the AGC part of this circuit works, but it appears to be accomplished via the 100k resistor between Q5 and the pulse input.

Hi Qiaozhi, where did you find Q5 in those AGC - TR CM1000 schematic?

I am not sure that in this case TR mean "Transmit - Recieve" but maybe ThReshold or something else. Regarding Whites terms glossary TR "Usually describes non-ground rejecting detectors or modes.", but CM1000 is ground rejecting, so TR should mean something else.

[Qiaozhi]

Hi Qiaozhi, where did you find Q5 in those AGC - TR CM1000 schematic?

Absolutely no idea.
The only possible answer is that I made that post after midnight.
I should have referred to the CD4024, so maybe I was looking at pin 5.

I am not sure that in this case TR mean "Transmit - Recieve" but maybe ThReshold or something else. Regarding Whites terms glossary TR "Usually describes non-ground rejecting detectors or modes.", but CM1000 is ground rejecting, so TR should mean something else.

I agree. In this case it probably means "threshold".

[kt315]

Don, I did draw a schematic of TR in 2004 but I did not remember for whom... thank you, I see your one now and what it was.

[metal mania]

great book excellent read one question about probe concerning battery does it need to be a tesco battery as I dont shop there or will an asda one suffice thanks

[lhartouka]

thank you

[cboyer1324]

Hello,

I attempted to build the probe based off the ITMD2 book design. I am unsure how I should connect the ground on a breadboard. I right now have all the 0v grounds connected to a rail that goes to the negative end of the C6 cap on the 78L05. The way I am reading the diagram shows the -9v terminal floating when the SPST switch is connected to R6. I also noticed the GERBER on the site that I used to make the board has a U4 that is not included on the ITMD2 circuit and is missing the R7 pot on the board. Is this something that purchasing either ITMD first or third addition would clear up?

[Carl-NC]

Connect the grounds just like the schematic says. SW1 is the on/off switch and disconnects the (-) side of the battery instead of the more usual (+) but it works the same either way. When SW1 is switched off it then discharges C4 via R6.

I have no idea the Gerber, where did you get it from and does it have a schematic? The probe project is identical in ITMD1 and was not included in ITMD3.