This is the inside of the regulated power supply for the 50EH5 / 25EH5 tube filaments. It uses an LM317 voltage regulator and an old VCR power transformer that had just the right voltage and current ratings for the filaments of the 50EH5 / 25EH5 tubes. The output from the regulator is set for 20 some volts for the 25EH5's, and the unregulated DC is about 45V for the 50EH5's.
