PI front-end PCB revisited

[Carl-NC]

I'm embarrassed to say, 5 months after my original post on this, that I never ordered the PC boards. Personally, I've been too busy to have done anything with the boards if I had them, but I know several others were interested in this idea, so I will follow through and get the boards made.

One last chance for feedback... the schematic in the original post is still the same, the layout was shown in this thread. This is strictly the TX drive and RX front-end... no clocking, no power supply, no integrator. Also, please keep in mind that component values in the schematic are meaningless, I made no attempt to set values to anything useful.

- Carl

[bbsailor]

PI front end

Carl,

I am still interested in obtaining your experimental PI front end circuit board.

I would think that the next logical circuit board would be the timing circuits.

Ultimately, if there is enough interest, I would think that this group, with input from members, could design a small motherboard with the power supply and backplane for common connections, common and shared pulses and space for various plugins such plugins as:
1. TX MOSFET coil driver and predriver
2. RX Preamp for mono and DD coil
3. Timing circuits and delay circuits
4. Integrator and related circuits
5. Audio output and optional peak limiter
6. A to D converter (optional)
7. Digital post processing (optional)
8. Universal external interface board (optional)

The first step would be defining the most useful common connections on the motherboard so that the subsequent plugins could have a common pin design.

I would anticipate that the mother board would be about 3" wide by 5" long.
Each plugin would be 1.25" tall by 3" wide and be spaced .75" apart on the motherboard. This should provide enough board space for some some creative options and easy experimenting.

I also envision an universal interface card where signals from the motherboard or specific points on each plugin card could be easily brought out to external, edge mounted BNC connectors for benchtop experimentation.

These are just some of my preliminary thoughts, like thinking out loud. They were stimulated by Carl's introduction of the experimental front end board. I am just carrying his idea to the logical conclusion.

Carl, thanks for the great web site and the PI resources that you provide to experimenters. I hope others jump in and contribute.

bbsailor

[Carl-NC]

"Ultimately, if there is enough interest, I would think that this group, with input from members, could design a small motherboard with the power supply and backplane for common connections, common and shared pulses and space for various plugins such plugins as..."

I had thought of this when I designed the front-end PCB. I chose not to do it that way, because...

• I felt it would take a bit of up-front planning to figure out a decent backplane configuration.
• I didn't know if I would have time to actually follow through on the other modules, and didn't want to leave such a system half-done.
• I'm concerned about noise coupling.
• The front-end board is fairly large using through-hole, and would make a backplane system bulky. SMT would be a better choice.

However, since it's been brought up, I'll listen... anyone else interested in discussing a modular backplane design?

- Carl

[Carl-NC]

I whipped out a plug-in PCB for the front-end this morning. This was quick-and-dirty, nothing optimized or checked, it's just to see what it would look like. What I found was,

• Board is 3"x3". I could shrink it, but only slightly.
• I stuck with single-sided for cost. This makes the edge connector 25 pins, which is not enough, in my opinion, for the entire backplane, unless pins are reassigned on different boards, which limits flexibility.
• Double-sided would allow 50 pins for a 3" board, and would be far better.
• But would increase board cost. And such an approach would require, say, 4 modules (power, clocking/PIC, TX/RX, and back-end analog/PIC) plus backplane, so $40-$50 in PCBs alone.
• SMT would shrink board size by half or more, especially utilyzing both sides.

Frankly, I'm not inclined to persue this, without A LOT of interest from other folks. And maybe some other folks taking on parts of the project.

- Carl

[amtech2005]

pi front end revisited

Hello, put me down for 2 please,but only if there not the smt tiny size,because I have 2 standard original through hole boards,I dont want to mix and match. Thank-you Eugene [email protected]