Oscilloscope pong for 1 or 2 players.

[GK]

For those making a public source design, I would recommend making a second inverted 'Z' in case their scope or x/y display blanks on a low Z signal input instead of a high.

I wonder if there are many 'scopes that operate that way of if there are some out there which actually require a negative polarity pulse to blank their beams? Perhaps it would be useful if members out there could consult their manuals or just hook a function generator up to the Z input of their analogue oscilloscopes, so some kind of general list of requirements can be drawn up? 

[GK]

OK, when you (anyone) eventually gets a copy of this machine up and running , you're going to have to adjust a few trimmer potentiometers. This attached diagram tells you all you need to know.

[FrankBuss]

For those making a public source design, I would recommend making a second inverted 'Z' in case their scope or x/y display blanks on a low Z signal input instead of a high.

I wonder if there are many 'scopes that operate that way of if there are some out there which actually require a negative polarity pulse to blank their beams? Perhaps it would be useful if members out there could consult their manuals or just hook a function generator up to the Z input of their analogue oscilloscopes, so some kind of general list of requirements can be drawn up?

My DSO-X 3012A digital scope has a 1.4 V blanking threshold, using the external trigger input at the back. If the voltage is higher, it blanks the trace in X/Y mode. But I guess it doesn't look nice on these modern digital scopes. I have a Voltcraft AO 610 analog scope, too, but unfortunately it doesn't have a blanking input. But from your LTspice waveforms it looks like it might still work, but with thin traces between the graphical elements.

[FrankBuss]

While searching for a nice scope with Z input, I found this:

http://www.digimessinstruments.co.uk/manuals/german/mmoseriesengandger.pdf

On page 20 it says: "The Z axis terminal on the rear of the unit allows adjustment of the intensity using an external signal. The characteristics are positive level for improved stability and negative level for increased intensity of the waveform.". I really don't know what they mean with "stability" (and the German translation at the end of the document makes no sense at all), but sounds like it blanks on positive voltages, too. We'll see, I can get it for EUR 49 from eBay, if no one other bids

[timb]

Why have the SMT parts already soldered? That always bugs me, just let me build the whole kit. If someone is going to have a use for something as esoteric as analog oscilloscope Pong, they ought to be able to hand solder SMT parts. We're not talking 672 pin BGAs here.

It's a lot of SOT-23 parts to solder by hand, but personally I wouldn't mind doing them all by hand, soldering is sort of like meditation for me. I guess other people are the same?

Yes, squiggly traces are imperative for the vintage look.

Oh yeah, I already started laying out the first schematic last night as a test. I'm going with curved traces for a hand taped out look. It's driving my pseudo-OCD over the edge a bit, since things aren't perfectly aligned like I'm used to, but I'll adapt!

I think it should be all through-hole, looks more authentic

+1 , and also sort of 70s style pcb layout.

I may have a good source on the TH transistors, stay tuned!

Amazing work, GK! That's a lot of point-to-point-to-point-to-point-...

Tim, looking forward to seeing your kit of it. Perhaps have the option to assemble everything, including SMT parts.

Yeah, after seeing the response here, I think that's the way to go!

Any JFET substitute needs to have max. Vgs-off spec comfortably under -10V and preferably not an order of magnitude greater junction capacitance than the 2N5484. The latter in particular needs to be watched in this application because the JFET capacitance is hanging on the sensitive virtual earth node of discrete op-amps. Some ultra/very low Rds-on "switching" JFET types can have very high junction capacitances, so be careful.

I think it should be all through-hole, looks more authentic Would this JFET work? http://www.digikey.de/short/32rhf3

Keep in mind that, in a lot of cases, TH parts are considerably more expensive.

I may have come up with a way to allow SMT *or* TH transistors to be used on the same board, without adversely affecting the layout. The idea being the board could be offered as a kit with all the parts (using SMT transistors) *or* you could maybe buy just a board (or have one made from the gerbers) and buy the TH parts yourself. That might suit everyone.

[timb]

OK, when you (anyone) eventually gets a copy of this machine up and running , you're going to have to adjust a few trimmer potentiometers. This attached diagram tells you all you need to know.

Hey GK, can I get high resolution copies of the schematics? The ones posted her get pixelated when I zoom in. The original scanned resolution would be super helpful!

You can email them (sysop AT timb DOT us) or send a Dropbox link or whatever. That would be super helpful!

(I tried PMing you, but you've got it turned off.)

Thanks!

[bitseeker]

Yes, squiggly traces are imperative for the vintage look.

Oh yeah, I already started laying out the first schematic last night as a test. I'm going with curved traces for a hand taped out look. It's driving my pseudo-OCD over the edge a bit, since things aren't perfectly aligned like I'm used to, but I'll adapt!

Hang in there, Tim!

[GK]

My DSO-X 3012A digital scope has a 1.4 V blanking threshold, using the external trigger input at the back. If the voltage is higher, it blanks the trace in X/Y mode. But I guess it doesn't look nice on these modern digital scopes. I have a Voltcraft AO 610 analog scope, too, but unfortunately it doesn't have a blanking input. But from your LTspice waveforms it looks like it might still work, but with thin traces between the graphical elements.

I think this application is a good excuse to get another analogue oscilloscope Here are screen photos with and without z-axis blanking, displayed on both my ancient Tek 422 and even ancienter Tek 545B.

Without blanking the beam artifacts aren't too bothersome so long as the intensity isn't turned up too high. Keep in mind though that these photographs make the situation without blanking appear significantly less bad than it really is. The camera seems to be a lot more sensitive to the colour of the light emitted by the CRT phosphor than is the human eye. In the photos the display looks really bright and a bit plumed, but in reality I had the intensity turned down as low as is acceptable for comfortable viewing.

[GK]

Oh, one last schematic diagram - the power supply. It's getting really technical now! 2N3055/MJ2955 for that '70s look. Other benefits are that the cans can dissipate the required power without heatsinking and the transistors will easily survive a momentary short on the output if you slip with your DMM or scope probes (unless you use a 300VA toroid or something for the power transformer).

Measured supply rail current on the positive rail with the audio volume at a comfortable level averages about 220mA and the negative rail averages about 120mA. Probably being a bit pedantic here, but please ignore the current readings on my crappy Powertech bench supply visible in the posted video. They aren't accurate a all.

[GK]

Hey GK, can I get high resolution copies of the schematics? The ones posted her get pixelated when I zoom in. The original scanned resolution would be super helpful!

You can email them (sysop AT timb DOT us) or send a Dropbox link or whatever. That would be super helpful!

(I tried PMing you, but you've got it turned off.)

Thanks!

OK, I've up-loaded full-res PDFs here:

http://www.glensstuff.com/pong/

BTW, w.r.t. kit-setting; if the intent is just a service to members here in the same spirit that I shared the design in the first place then I am fine with that; but definitely iffy if the broader intent is commercialisation outside of the forum community.

One you've drafted the schematics you can send them to me for double checking if you want. I can download either the free or the 30-day trial version of Diptrace.
 

[ajb]

This could make a really phenomenal instructional kit, if you were amenable and if someone were willing to put in the work to create the additional materials.  If the circuit were broken up into discrete sections that could be built up and tested one at a time, for each section you could have:

-  a brief intro ("we want to draw this shape, that means we need to generate these sorts of signals")
- the relevant schematic and a description of how it works
- assembly instructions
- then testing/adjustment/troubleshooting instructions with some example waveforms, and maybe some more in-depth discussion of the circuit operation with implementation advice.

It would be a lot of work, but it would be a great opportunity to learn about so many analog building blocks.

[timb]

Hey GK, can I get high resolution copies of the schematics? The ones posted her get pixelated when I zoom in. The original scanned resolution would be super helpful!

You can email them (sysop AT timb DOT us) or send a Dropbox link or whatever. That would be super helpful!

(I tried PMing you, but you've got it turned off.)

Thanks!

OK, I've up-loaded full-res PDFs here:

http://www.glensstuff.com/pong/

BTW, w.r.t. kit-setting; if the intent is just a service to members here in the same spirit that I shared the design in the first place then I am fine with that; but definitely iffy if the broader intent is commercialisation outside of the forum community.

One you've drafted the schematics you can send them to me for double checking if you want. I can download either the free or the 30-day trial version of Diptrace.
 

Thanks! Once I get back to my computer tonight I'll grab those. That'll make it a lot easier to convert. I can also send you the DipTrace schematics in PDF form if you don't want to download DipTrace. (I've got Ghostscript setup as a PDF printer.)

My intent was just to share it with the forum community. I figure once the boards are done, I'd see how many other people want them, order a batch and then order enough parts to do them all. The parts will obviously be a lot cheaper if ordered in larger quantities. (If just five people are interested in kits the price can be almost cut in half!)

I'm doing this because I think it's an awesome project and I want one myself! It's also a bit of a challenge to do layout for. I'm not looking to commercialize it or to make any money off it; any parts kits would be sold to forum members at cost.

I did plan on releasing the Gerbers and a full BOM though, assuming you're alright with that.

I captured and laid out a small section less night in both SMD and TH varieties, to see how much space each took. Using SOT-23 transistors and 1206 resistors/capacitors takes up about 1/3 less board space than TH parts, is easier to layout and may be cheaper (and easier to get) to boot, on the other hand, TH does look a lot more authentic, so I'm a bit torn which direction to go.

[bitseeker]

That's a tough one, Tim. THT does maintain the right look and feel. However, an SMT board 1/3 the size is also appealing and 1206 is reasonable.

[james_s]

How about both? Do a layout for TH and do another layout for SMT. My vote would be 0603, but I have loads of passives in those sizes.

[BrianHG]

How about both? Do a layout for TH and do another layout for SMT. My vote would be 0603, but I have loads of passives in those sizes.

O805, or 1206, you want clean clearance for traces to go under the SMD part for those of use who might do home made copper clad etchings without the fine resolution of a pro-made PCB or the right SMD assembly tools.

[GK]

Thanks! Once I get back to my computer tonight I'll grab those. That'll make it a lot easier to convert. I can also send you the DipTrace schematics in PDF form if you don't want to download DipTrace. (I've got Ghostscript setup as a PDF printer.)

My intent was just to share it with the forum community. I figure once the boards are done, I'd see how many other people want them, order a batch and then order enough parts to do them all. The parts will obviously be a lot cheaper if ordered in larger quantities. (If just five people are interested in kits the price can be almost cut in half!)

I'm doing this because I think it's an awesome project and I want one myself! It's also a bit of a challenge to do layout for. I'm not looking to commercialize it or to make any money off it; any parts kits would be sold to forum members at cost.

I did plan on releasing the Gerbers and a full BOM though, assuming you're alright with that.

That's all cool. I don't care if you actually make a few trivial bucks here; it's just about fair use of IP, not any anti-capitalist ideology.

The last time I did something like this I sold off the boards above cost (though not by much); not as a money making endeavour as it hardly compensated my time invested (post office trips, filling out customs forms, blah, blah) but just to ensure that after sundry expenses (variations in postage costs to different countries, fuel for 6.3L car engine, etc) the endeavour wouldn't see me in the red.

Heck, if it means enabling half a dozen other members here to get duplicate builds up and running I think you could fairly recoup the cost of your own build; it would only be a knob that would get enviously or narky at you for that.
       

[BravoV]

Tim, thanks for the work, count me in for THT board, I can source the components my self.

Hope I can still source TO-18 style transistors.  Also planning to find the 70s or 80s style enclosure, the step down transformer too.

Btw, the reason I prefer THT is the excitement and the fun during the assembling, at least for me, cause once finished and working, realistically I won't be playing this on my scope everydays, only once in a while or probably bring it and brag it among friends. 

[timb]

That's a tough one, Tim. THT does maintain the right look and feel. However, an SMT board 1/3 the size is also appealing and 1206 is reasonable.

Exactly.

Here's the components for just the "Velocity Integrator" portion of the circuit in SMD and TH:







As you can see, component area is significantly less with he surface mount parts (maybe even less considering some could be placed on the bottom of the board as well). Obviously I could save space by doing the resistors in a vertical format, though personally I'm not a fan of that.

Based on parts count and some quick layout tests, I think the surface mount design would easily fit on a couple of 100x100mm boards that would be stacked. (Ideally I'd like to stay at that size since they can be inexpensively fabricated. Though I do have access to a US fab that will do 200x200mm boards on the cheap.)

The more I think about this, the more I like the esthetics of a TH layout, but man things would be easier with a SMD design!

Tim, thanks for the work, count me in for THT board, I can source the components my self.

Hope I can still source TO-18 style transistors.  Also planning to find the 70s or 80s style enclosure, the step down transformer too.

Btw, the reason I prefer THT is the excitement and the fun during the assembling, at least for me, cause once finished and working, realistically I won't be playing this on my scope everydays, only once in a while or probably bring it and brag it among friends. 

For what it's worth, if I did an SMT board it could still all be hand soldered as I'd use large pads to make it easy. 1206 and SOT-23 can all be hand soldered with nothing but an iron, some flux and semi-fine solder.

In the end, even if I go TH at least a few parts would possibly still need to be SMT, like the JFETs which are obsolete in TO-92. (Unless I get a suitable replacement.)

[BrianHG]

Timb, just in case, pay attention to via hole size and placement.  If you were to publish the gerbers for those who want to etch a 2 layer PCB, remember that they might be soldering wires from top to bottom for their vias and some through hole components.

Remember, we may be drilling the holes with a cheap dremel drill press...

[timb]

Timb, just in case, pay attention to via hole size and placement.  If you were to publish the gerbers for those who want to etch a 2 layer PCB, remember that they might be soldering wires from top to bottom for their vias and some through hole components.

Remember, we may be drilling the holes with a cheap dremel drill press...

Yeah, I thought about that! I've never home etched a complex double sided board before, what do you think is the smallest hole most people can reliably drill at home with a cheap drill press?

[bitseeker]

The more I think about this, the more I like the esthetics of a TH layout, but man things would be easier with a SMD design!

It is more period appropriate to go TH.

I guess this means I'll have to fix my old analog scope.

[james_s]

I don't recall the size, but when I was etching double sided boards I used a drill that was just right for a close fit of a piece of stripped wire wrap wire that I used for the vias. My PCB drill is home made, wooden frame made of 2x4 lumber with a precision slide screwed to it. I found it worked much better than those cheap Dremel drill presses, lots fewer broken bits.

[tautech]

Timb, just in case, pay attention to via hole size and placement.  If you were to publish the gerbers for those who want to etch a 2 layer PCB, remember that they might be soldering wires from top to bottom for their vias and some through hole components.

Remember, we may be drilling the holes with a cheap dremel drill press...

Yeah, I thought about that! I've never home etched a complex double sided board before, what do you think is the smallest hole most people can reliably drill at home with a cheap drill press?

0.6mm (24mil) no problem, never tried smaller.

[BrianHG]

Yeah, I thought about that! I've never home etched a complex double sided board before, what do you think is the smallest hole most people can reliably drill at home with a cheap drill press?

I know this will sound big and ugly, but make the hole at least 12mil, the outer diameter 30mil.  The reason for the huge size is that when exposing home made boards, the top and bottom layer aren't always perfectly aligned and also when drilling though, a slight error in alignment can push off the copper pad on the other side if it is too thin.

The smallest I would go would be 10mil drill with 26 mil outer diameter, but, the above measurements would be better.
Careful with your transistor & passive component library, make sure they don't have smaller holes than what I've listed above.
For transistors, make sure the TO-92 has a the wide off-center center pin footprint spacing.  Since we might need to solder on the top and bottom, if the center pin is pushed back, soldering on the top of the PCB is much easier to do without shorting to the 2 adjacent pins.  Everything else should be easy to solder on both sides.


For the traces, I would mostly route 12mil, saving 10 mil when going under 1206 smd caps and resistors & sot23.

[Fire Doger]

WoW very nice!!!
At university we had an HP scope (I don't remember model) with tetris, scope games are awesome

Machine vs machine ends at some point or goes to max freq and still playing?