Hmmm, those little TO-220 heatsinks probably have a thermal resistance in the vicinity of 25-30 deg.C/W. The positive rail one will be sweltering at around 80 deg.C at a minimum at room temp. given the current consumption of the positive rail, not counting the possible additional drain of an add-on scoring unit. 800mA will melt some silicon.
15VAC rather than 18VAC input will give you enough regulator headroom with adequate filtering after rectification, and about half the power dissipation.
The trimmer potentiometers for adjusting the regulator output voltages should be shifted to the feedback resistor leg between the control transistors base and ground. That way if the trimmers wiper goes open circuit the rail voltage will collapse to around 7V, rather than go in the opposite direction and saturate close to the unregulated input potential.
Those heatsinks are surprisingly good, much better than the crappy stamped metal ones you normally see. I tested it pulling about 300mA and case temperature got up to about 70c, that's with a 18VDC input.
Edit: These heatsinks have solder pins, so I've got them hooked to the ground plane to increase thermal dissipation.
An 18Vct transformer is the maximum I would recommend, but it would work best with a 15Vct transformer, yes. (In fact, on the layout PDF that should have said "18-0-18 Max Input, 15-0-15 Min Input" but I forgot to change it.
Current limit can be lowered by simply increasing the 1ohm resistor to 1.5 or 2 ohms. Though, the idea is to more or less prevent a dead short from immediately blowing the power transistor, rather than protecting it during a sustained fault. I may have a simple method of implementing snap back current limiting, but I'm not sure it's worth it overall.
Good catch on the trimmer; that's the way I originally had it wired up on the breadboard.
I think it is important, as someone may use a big-ass transformer they just happen to have available, which could make a lot of smoke.
BTW you appear to have forgotten a centre-tap connection for the transformer. Obviously you need 2 PFs.
May also be worth adding a footprint (connector or links) for DC-in, in case someone already has a suitable supply.
Okay, Polyfuse it is. Good catch on the center tap! I can't believe I forgot that... I'll switch the connector over to a 3-way.
I figured the user could just push +-18VDC in through the regular AC input, but if you think it would be worthwhile, I'll make provisions.