Author Topic: Oscilloscope pong for 1 or 2 players.  (Read 141002 times)

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Online MK14

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #150 on: March 28, 2017, 10:41:27 pm »
Great to have the waveforms on the schematic. Like the old days of CRT TVs and Video Cassette players.  :-+

That is nearly exactly what I thought. The schematic does seem to have a sort of vintage look to it (in a NICE way!).
Which goes well with the entire project.
 

Offline timb

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Oscilloscope pong for 1 or 2 players.
« Reply #151 on: March 28, 2017, 10:44:36 pm »
And good old test equipment service manuals.

Yes! You know I realized not too long ago that the way I draw schematics mirrors the schematics from old service manuals. I tend to put a lot of waveforms and instructional callouts in them. I even got in the habit of doing it the way Tektronix did if I had a lot of waveforms I needed to show (that is, putting the waveforms on a separate sheet and placing a symbol and letter next to the location of that waveform on the actual schematic).

Since I don't do nearly as much analog work these days there's not a lot of waveforms to show, but it's still helpful for things like how the power supplies should ramp up, or the correct timing on a digital bus. My customers seem to really like it and it ends up being good documentation instead of just a schematic.

« Last Edit: March 28, 2017, 10:47:03 pm by timb »
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Offline bitseeker

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #152 on: March 28, 2017, 10:46:40 pm »
Thanks for all the time you're putting into this, Tim. I'm looking forward to exploring all the analog goodness along with your schematics/docs.
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Offline timb

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #153 on: March 28, 2017, 11:02:43 pm »
Thanks for all the time you're putting into this, Tim. I'm looking forward to exploring all the analog goodness along with your schematics/docs.

I appreciate that! However, to be fair GK really did all the hard work in creating the project and documenting it by hand. Making a digital schematic is a cakewalk by comparison. I'm really glad GK has been OK with me doing this; bringing such a cool project to other people feels good. :)

Now the hard (and fun) part for me has arrived for me: Doing the layout! I'm going to start tonight, but man, this is going to be a *beast* to route. It didn't really hit me until I looked at the complete BOM: Over 700 parts! Nearly 200 transistors, 200 diodes, hundreds of resistors! All on two, 2-layer boards.

I've routed digital boards with twice as many parts, so you'd think it would be easy, but that was on a 6-layer board and a lot of the routing was simple busses going from one part to the next.

When I first start a new project, as soon as I see (or finish) the schematics my mind instantly starts chewing on how it could be routed. So the auto-router in my brain has been going non-stop since GK first posted the schematics awhile back. It's been a fantastic mental puzzle to work on and I can't wait to start this evening.

I'll post screenshots of my progress each night for comments and review, if you guys want.
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Online BrianHG

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #154 on: March 28, 2017, 11:13:01 pm »
Take it a section/function module at at time.  Don't be pressed to fit each section into the smallest most compact possible layout.
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Offline timb

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #155 on: March 28, 2017, 11:23:15 pm »
Take it a section/function module at at time.  Don't be pressed to fit each section into the smallest most compact possible layout.

Yeah, I've already got all the parts grouped by sheet to start with. Obviously it won't stay like that for the entire board, as some things will have to mix in order to route the nets in the available space.

Space is an issue, however I think I've got a solution lined up if I end up running out of it, without going to a third full sized board.
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Offline tautech

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #156 on: March 28, 2017, 11:33:13 pm »
Take lots of short rests from the routing Tim, each one will freshen the mind and you'll see paths, solutions and things you were too tired or cross eyed to see.
Keen to see you efforts.  :)
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Offline bitseeker

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #157 on: March 28, 2017, 11:33:39 pm »
Thanks for all the time you're putting into this, Tim. I'm looking forward to exploring all the analog goodness along with your schematics/docs.

I appreciate that! However, to be fair GK really did all the hard work in creating the project and documenting it by hand. Making a digital schematic is a cakewalk by comparison. I'm really glad GK has been OK with me doing this; bringing such a cool project to other people feels good. :)

Very true. Thank you GK for sharing your project with us!
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Offline GK

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #158 on: March 29, 2017, 09:33:20 am »
Very true. Thank you GK for sharing your project with us!



No problem. The equivalent circuit of the Multiplexer Logic. I'm only able to churn these out one sheet per evening...............

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Online BravoV

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #159 on: March 29, 2017, 09:49:54 am »
Its awesome !  :-+

Not only the board, the documentation is now like old Tek's style, attached example of old Tek's schematic.

Offline timb

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Oscilloscope pong for 1 or 2 players.
« Reply #160 on: March 29, 2017, 10:42:47 am »
Okay, here's today's updates:

Laid out the reference regulator:

http://timb.us/PDF/Scope_Pong_Reference_Regulator.pdf
(Orange traces are bottom layer, black is top, pads with no connection connect to GND pour.)





I think I could make it a bit more compact and there's a couple of places where I could perhaps position things more efficiently, but it's a good start.

I also added an option for an inverted Z-Axis output.



I've updated the schematic to reflect this change:

http://timb.us/PDF/Scope_Pong_20170329.pdf
« Last Edit: March 29, 2017, 10:49:59 am by timb »
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Offline GK

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #161 on: March 29, 2017, 12:51:30 pm »
Looks neat; I think you'll have this knocked off in no time  :)

I'm currently finalizing/polishing/amending my own schematics and I think a few more bypass capacitors should be added for good measure. The -15V rail of the Reference Regulator should be bypass to ground with an additional 100nF cap. Also the "inverter" op-amp in the Velocity Integrator schematic should have both its supply rails bypassed to ground with an additional pair of 100nF.

That should be sufficient. In my rats nest build I actually have plentiful 100nF bypass caps littered all around as they double as structural support for the components suspended above the ground plane. I just neglected those ones mentioned above when I scribbled the schematics.
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Offline GK

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #162 on: March 29, 2017, 12:55:17 pm »
I'm only able to churn these out one sheet per evening...............


OK, I lied, LOL. Here is the equivalent diagram for the Vertical Ball Movement circuit. Now I really have to log off and go to bed; I'm going to be a zombie at work again tomorrow, but then again being a public servant I guess no one will notice anything out of the ordinary  :P.

« Last Edit: March 29, 2017, 12:57:28 pm by GK »
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Offline timb

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Oscilloscope pong for 1 or 2 players.
« Reply #163 on: March 29, 2017, 01:18:55 pm »
Looks neat; I think you'll have this knocked off in no time  :)

I'm currently finalizing/polishing/amending my own schematics and I think a few more bypass capacitors should be added for good measure. The -15V rail of the Reference Regulator should be bypass to ground with an additional 100nF cap. Also the "inverter" op-amp in the Velocity Integrator schematic should have both its supply rails bypassed to ground with an additional pair of 100nF.

That should be sufficient. In my rats nest build I actually have plentiful 100nF bypass caps littered all around as they double as structural support for the components suspended above the ground plane. I just neglected those ones mentioned above when I scribbled the schematics.

I actually planned to add a bunch of additional bypassing around the board on the + and - 15V rails. Those will be on the power supply schematic once I finalize the design of my supply. (I'm waiting on a set of complementary darlingtons to arrive from Digi-Key to solder up a test circuit and verify stability. Simulations came out fine, but I want to be sure before committing it to real boards.)

I figured adding a bunch additional bypass was a good idea, considering the rails will be bussed across two large boards. I had also planned on adding footprints for a couple of small bulk caps at a couple of key points along the route. (They most likely won't be needed, but I'd rather have provisions for them just in case, so I don't have to bodge something in or spin another set of boards.)

Experience has taught me you can rarely have too much capacitance on a power rail. (Well, depending on the regulator technically you can, but...)

The latest equivalent circuit diagrams look great!

Also, are you keeping a log of any changes/amendments you make to your schematics? That would make it easier to back-annotate mine. (I don't mind doing it the old fashioned way, I just don't want to miss anything that may be critical.)
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Offline GK

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #164 on: March 29, 2017, 01:38:35 pm »
Besides those three additional bypass caps I haven't made any electrical ammendments. Everything is hunkydory in that regard. Ammendments have just been minor annotations, component designators to link to the equivalent diagrams. When done I'll upload the lot to that pong folder on my site and delete the old.
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Online BrianHG

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #165 on: March 29, 2017, 03:01:54 pm »
Timb, you got the center leg of the TO-92 bent to the front instead of toward the back where the round side of the case.
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Offline timb

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Oscilloscope pong for 1 or 2 players.
« Reply #166 on: March 29, 2017, 06:57:43 pm »
Timb, you got the center leg of the TO-92 bent to the front instead of toward the back where the round side of the case.

That's the way I've seen it done before in some old test gear, so I thought it was the standard. There's even a footprint for it like that, including 3D model, in DipTrace. (Though I ended up making my own footprint with a slightly different silkscreen, and my own 3D model with better looking leads.)

Come to think of it, I have actually seen the front pin bent toward the back on some TO-92s too. In this case, I basically copied the existing footprint and didn't give it much thought, as there's little documentation on the subject.

If it makes a big difference I can change it, not a big deal. (Though, keep in mind you're going to have to bend the leads out yourself either way, no matter what.

Edit: The only image of a TO-92 I can find with a bent center leg has it going backward, so I'll change it to that since it seems more common. I *have* seen them bent forward, maybe they're non-standard like that or something.
« Last Edit: March 29, 2017, 07:15:17 pm by timb »
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Offline tautech

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #167 on: March 29, 2017, 07:47:04 pm »
Any of the new TO-92 I have that have bent leads are backwards to the round side.
AFAIK it's the more common configuration. Other will chime in I guess.
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Offline bitseeker

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #168 on: March 29, 2017, 11:32:01 pm »
My recollection is that the center pin is bent toward the rounded side of the package (not that I really track common usage of the layout).

Aesthetically, it makes more sense to me for the center pin to be toward the rounded side because then the pins create a triangle where one side aligns with the flat side of the package (rather than having a vertex there). Also, it tends to center the package over the holes in the PCB, thereby making better use of the area.

Nevertheless, as long as it's consistent on all the PCBs for the project, I don't have a preference.
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Online BrianHG

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #169 on: March 30, 2017, 12:06:47 am »
The transistor also takes less PCB surface area if the center leg is bent to the rounded side.
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Offline james_s

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #170 on: March 30, 2017, 12:14:00 am »
There's no official standard, I've seen it done both ways. Just go with whatever makes the layout simplest to create, you can even have some one way and some the other way if that makes placement easier. It's not as if it's difficult to form the leads, although consistency does make it less likely for an assembly error to creep in.
 

Offline GK

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #171 on: March 30, 2017, 07:53:55 am »
I've updated the schematic to reflect this change:

http://timb.us/PDF/Scope_Pong_20170329.pdf


C508 in the audio amplifier is 100nF instead of 100pF.
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Offline timb

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Oscilloscope pong for 1 or 2 players.
« Reply #172 on: March 30, 2017, 10:08:17 am »
I've updated the schematic to reflect this change:

http://timb.us/PDF/Scope_Pong_20170329.pdf


C508 in the audio amplifier is 100nF instead of 100pF.

Good catch, thanks! Will fix today.

Okay, I fixed the the TO-92 pins:



I had the change the routing a bit to cope with the new pin configuration. To be honest, I think it would have ultimately been easier to route with the pins the other way, but I was able to make things a bit more compact with the new footprint, so it's all good. (I don't want to squeeze things any closer than this, to allow for easy probing of parts of the circuit that don't have test points.)

http://timb.us/PDF/Scope_Pong_Reference_Regulator_r002a.pdf
« Last Edit: March 30, 2017, 10:18:06 am by timb »
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Offline timb

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #173 on: March 30, 2017, 10:16:39 am »
There's no official standard, I've seen it done both ways. Just go with whatever makes the layout simplest to create, you can even have some one way and some the other way if that makes placement easier. It's not as if it's difficult to form the leads, although consistency does make it less likely for an assembly error to creep in.

Yeah, I'll stick with one way or the other in this case. If it was a small circuit with a dozen transistors it would be one thing, but this is hundreds, so I think keeping it simple is the way to go.

I've also added a little NPN and PNP silkscreen symbol to the center of the footprints, to aid in correctly populating the boards. (This isn't shown in the photo/PDF above.)
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Online BrianHG

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Re: Oscilloscope pong for 1 or 2 players.
« Reply #174 on: March 30, 2017, 07:22:09 pm »

I had the change the routing a bit to cope with the new pin configuration. To be honest, I think it would have ultimately been easier to route with the pins the other way, but I was able to make things a bit more compact with the new footprint, so it's all good. (I don't want to squeeze things any closer than this, to allow for easy probing of parts of the circuit that don't have test points.)


Do not worry about this.  You re-worked an existing routed section.  You will not have this issue as you start routing the rest of the PCB fresh.  Just rotating some of the transistors by 180 or 90 degrees in the current section would have simplified routing quite a bit, but for such a large circuit, leave it the way it is, it's perfectly fine.
« Last Edit: March 30, 2017, 07:26:03 pm by BrianHG »
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