Finished board: set for 9.1V
The A/C transformer is good for 16VAC.
I measured about 22VDC after rectification (root 2 * 16)
A 5.1V Zener followed by a 1N4003 Diode clips part of the 60Hz
so that I can experiment with a 60Hz signal for my TTL work
Just another picture; as this is a cheapie Vivicam 3350 that's
really meant for outdoors. I use a low-watt flourescent lamp to try to keep the contrast reasonable.
PCB for LM317 PSU and 5.1V 60Hz tap
hand-made PCB, etched with Ferric Chloride and done too late at night. The extra copper is me just playing around with various electrical tapes to see what resists etchant. The traces were standard rub-on resists (vintage RS....)
Finally for fun I used a Staedtler Lumocolor 313 RED marker to free- hand write things like "PSU" and the date. Note that the date is really undercut. Resist pens are not the way to go...
You might notice the single RED line (just about the 60Hz copper and the 'ZD' pencilled notation). That's what comes of doing things late and just doing a cursory check. I missed a whole trace: That Zener's not going to ground itself you know! But I keep a record of the mistakes too, 'cuz that's how you learn!
Did I mention I'm learning a lot? OK, important safety tip: Ceramic capacitor voltage ratings need to be observed! My 0.1u bypass cap on the inputs and outputs were 25V. When I initially tested this thing, I used two 9V batteries on the input. Simple test, and let me perfunctorily check the regulator's operation.
As it seemed to work, I threw a third 9V battery into the mix. As my years of Higher Math have "larned me", 27 volts is but two more than the input cap's rating. Poof. Those extra two volts sure got out of there in a hurry!
OK, the ceramic with the hole in it was a dead give-away. But even after I removed it I found that the + and - inputs (just after the Bridge) were shorted. So I pulled the other 0.47u/35V Tantalum (which was correctly inserted with the correct polarity). It had shorted too, so the regulator refused to function until I replaced it.