A Simple Interval-Programming Circuit.

C et al. (1960) drew a wiring diagram for a cheap interval timer.

The circuit plugs into any operant chamber. It delivers food or tokens on fixed or variable schedules.

Parts cost a few dollars and the board fits in your hand.

The paper does not give new data. It gives a recipe.

Follow the steps and you can run FI, VI, FR, or DRL without buying pricey commercial gear.

Long et al. (1958) showed kids can work on intermittent schedules two years earlier, but they had to borrow lab gear. The 1960 note lets any lab build its own timer, so child studies become cheaper.

Mahoney et al. (1971) later tracked pigeons’ pauses across fast-changing intervals. That work needs millisecond timing; the 1960 circuit gives the backbone.

SHETTLEWORTCHARNEY et al. (1965) used the same DIY box to time brain-stimulation reinforcement. Same schedules, same hardware, new reinforcer — proof the circuit is flexible.

If you run lab sessions or train staff, you can solder this board in an afternoon. It still beats modern quote prices. Use it to teach schedule control, demo FI scallops, or power student projects without draining the grant account.