Make Electronics

Chips, Ahoy! 221

Experiment 23: Nice Dice

1K

1K

1K

0.1uF 0.01uF

D1

D2

D3

D4

5V DC regulated power supply

1 8

555

74LS 92

74LS27

74LS06

Each

resistor

below

is 120

ohms

10K

10K

68uF

Figure 4-111. If open-collector inverters are added to the dice
schematic, it can drive full-size LEDs with up to 40mA, as long as
the LEDs are turned around to sink current into the TTL output
stage instead of trying to source current from it.

Figure 4-112. The completed circuit using an open-collector

inverter to drive full-size LEDs.