75 years ago this month, this father, shown in the December 1942 issue of Popular Mechanics, engages in some troubleshooting of the family’s radio receiver while the kids look on admiringly.
He didn’t let wartime shortages of test equipment hamper his efforts. As the magazine suggests, he’s using a neon lamp with clip leads to trace the circuit. For checking continuity, the lamp can be used with a 22.5 volt battery.
Despite the high voltages (as evidenced by the power transformer on the chassis), there’s no evidence to indicate that the kids got zapped by poking their fingers into the wiring. And chances are, they both turned out OK, despite the exposure to secondhand smoke.