Interval timer (CB7504E)

Among other applications, the 1960 Sylvania transistor manual indicates this timer for chess matches. The components admit equivalents.

Linear Scale Ohmmeter (CB5932E)
Similar circuits can be found on this site. This is from an 80's American documentation. The...
48 V to 15 V step down converter with 1.5 A (CB1572E)
To operate with high input voltages using a 3-terminal voltage regulator such as the LM340-15, we...
Multitester (CB4470E)
This simple multimeter takes advantage of the low cost common galvanometer of 200 uA or 1 mA and...