PI5 from ITMD

[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]

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]

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

[geoscash1]

10k Trimmer

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

[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]

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]

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.

[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.

[bernte_one]

has someone drawn a pcb layout with the new schematic?

[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]

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

[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]

thanks, not bad

will see what i can do, maybe i will post first results next weekend
many thanks

p.s. i love your avatar it reminds me of my wife 12 years before

[Qiaozhi]

I am in the process of building it right now but it takes me a while longer because I use perf board
for builds.

I use DIY Layout Creator for doing perfboard layouts -> http://code.google.com/p/diy-layout-creator/
It's freeware, and is platform independent. You need to have Java JRE/JDK 1.6.0_10 or newer installed.

[CAS]

I use DIY Layout Creator for doing perfboard layouts -> http://code.google.com/p/diy-layout-creator/
It's freeware, and is platform independent. You need to have Java JRE/JDK 1.6.0_10 or newer installed.

Thanks for that. I hadnt seen that one before. Easy to draw up small prototypes.