PI5 from ITMD

[geoscash1]

Hey bernte,

I have one done that a buddy did for me, but would like someone to go over it to double check it. I know its not beautiful but i'll tell ya, this was a little pain
to layout. Maybe you can simplify it. I am in the process of building it right now but it takes me a while longer because I use perf board
for builds.

Anyway, here is a pcb you can try or modify if you want.

[bernte_one]

hello geocash
if you would makea pcb layout by Hand drawing and can redraw it with software

[geoscash1]

I built 2 of these on the original design that didn't work but that was before Qiaozhi sent over the new schematic. I'll give the new one a whirl and try if I can to get a layout
done. I don't use pcb software and draw by hand so it wont look beautiful but it will work.

[bernte_one]

has someone drawn a pcb layout with the new schematic?

[Qiaozhi]

Regarding PI-5 in ITMD:

There appears to have been a major screw-up in Adobe FrameMaker when the book was assembled. Unfortunately the PI-5 schematic that got published was a very early version which has some problems (basically, it doesn't work). The figures were embedded and linked using OLE, and somehow the link was broken. So ... if anyone wants a copy of the correct PI-5 schematic, then ping me an email.

To prove that you actually do own a copy of ITMD, and are not just a leecher (a BITTORRENT term, in case you're wondering) please put the title of Fig 12-15 in either the Subject or body of the email.

[Qiaozhi]

Oh ok, just wanted to be sure what exactly it was for. It really could be an off board pot adjustment then if its something that's wanted externally.

Yes, it's intended to be an external pot.

[geoscash1]

My PI5 so far

Oh ok, just wanted to be sure what exactly it was for. It really could be an off board pot adjustment then if its something that's wanted externally.

Well this is where I'm at so far, I was short a few (three 100N's) caps so its unfinished but its almost done, have to wait on the caps now and my 556's...

[Qiaozhi]

Is the 10k trimmer at R12 (ITMD Drawing) used for controlling the pulse width or is it varying the frequency?

It varies the width of the blanking pulse.

[geoscash1]

10k Trimmer

Is the 10k trimmer at R12 (ITMD Drawing) used for controlling the pulse width or is it varying the frequency?

[geoscash1]

Okie dokie, I understand.... thanks for clarifying that...

I'm putting things together now (again) to redo or make another of this particular PI and have a few things to order yet but also am working
on a pic program that may eliminate a couple chips if I can get it right...lol

[Qiaozhi]

Hey Qiaozhi could you elaborate on that a bit, what is unstable about the power supply? I am using the ITMD schematic but will be using a556 instead of the 555's, if I end up with a pic micro there will be a 5v regulator but I am not sure about what you mean as far as it being unstable as is. I will be using a 12v supply...(8AA's)

I didn't mean to imply that the power supply (as it is now) is unstable. I was simply suggesting the use of a linear regulator might provide a "more stable" supply, which could increase sensitivity. Any potential improvement would depend on how much noise is currently generated on the supply rails when the mosfet turns on.

[geoscash1]

Hey Qiaozhi could you elaborate on that a bit, what is unstable about the power supply? I am using the ITMD schematic but will be using a556 instead of the 555's, if I end up with a pic micro there will be a 5v regulator but I am not sure about what you mean as far as it being unstable as is. I will be using a 12v supply...(8AA's)

It probably wouldn't hurt to increase the capacitance of C1 to 1000uF. In fact there's quite a few improvements that could be made, such as the use of linear regulators to create more stable power supplies.

[Qiaozhi]

Also, normally near the coil, C1 is usually a 1000uF (showing in original schematic), but this circuit in the ITMD is using a 100uF, is that correct or is it maybe a typo or would it really matter which is used?

It probably wouldn't hurt to increase the capacitance of C1 to 1000uF. In fact there's quite a few improvements that could be made, such as the use of linear regulators to create more stable power supplies.

[geoscash1]

556 instead of 555's

It appears that you are correct. However, the original circuit does work, so I can only assume that I spotted this issue (back in 2006) but never updated the schematic. Damn ... and I've only just put the whole thing back in its enclosure.

LOL.... Hey if it works then its all good, it must be connected right or I don't believe it would work with the pinout the other way.....


I'm switching to an LM556 dual timer to eliminate the two 555's... and really thinking may end up using a pic to replace that, I think a 12f629,12F675 or a 683 will do the trick.
Maybe a 16F628 to replace the 555/556 clock and have the ability to add the GB/Disc channels with other options as well... This could be a very scalable little project...

Also, normally near the coil, C1 is usually a 1000uF (showing in original schematic), but this circuit in the ITMD is using a 100uF, is that correct or is it maybe a typo or would it really matter which is used?

[Qiaozhi]

One thing I did notice on the old (original not in book) pdf drawing Qiaozhi posted is the pinout on the CD4011, according to my datasheet, the numbering on the original is not correct for IC3 (uc) a,b,c, and d. Shouldn't it be 1&2 in, 3 out, 5&6 in, 4 out, 8&9 in, 10 out and 12&13 in and 11 out? I may be wrong but that's what my sheet is showing for pinout..
[ATTACH]31207[/ATTACH]

It appears that you are correct. However, the original circuit does work, so I can only assume that I spotted this issue (back in 2006) but never updated the schematic. Damn ... and I've only just put the whole thing back in its enclosure.