Re: Defective/ fake LM317T
Wire length shouldn’t make a difference on the LM317 referring to “troubleshooting analog circuits” by Bob please.
What might be a problem is a 12v transformer. That’s 16.8V peak minus approx 1.2v across the diodes so 15.6v. Then there’s the ripple on the capacitor which is going to be large with a load on it and the 3V or so dropout voltage on the LM317 (minimum input vs output differential). It’s probably not regulating at all.
To get 15V out you need a much higher voltage transformer. 16V AC is pushing it. 18V AC better.
Also the LM317 won’t regulate without a minimum load. The resistor chain isn’t putting enough load on it, around 2mA. Stick a resistor across the output to pull this up to 10-20mA
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