What is it?

The circuit is technically called a bistable multivibrator. The word bistable refers to the fact that the circuit can exist in one of two stable states which we term ON and OFF. The circuit can be changed from one state to the other by applying an input trigger. Such circuits are often used to store single bits of information. A single circuit can be used to store one bit. When combined with other bistable multivibrators they can be used as frequency dividers because the output pulses have a frequency that are exactly one half ( ƒ/2 ) that of the trigger input pulse frequency. Another way of thinking about this is that a series of connected flip-flops can be used to count in binary. Each time a trigger is applied the count increases be one.

The state of the flip-flop is indicated by a LED.

Together with the circuit components we also supply detailed information on how the circuit works as well as assembly instructions. You can learn about steering diodes, integration of signals using capacitors and the operation of transistors.

Although a single flip-flop can be fun to build and test, its much satisfying to connect a series of flip-flops together to form a binary counter. For this purpose we also sell a full-Monty kit on Tindie that supplies 4 flip-flop kits, a debouncer kit, cables, a clock and AA battery holder.

NOTE: This is a kit that requires basic soldering skills.

Why did you build it?

I am interested in retrocomputing and thought I'd first try building a simple flip-flop.

Specification:

• Board Dimensions: 4.0 cm x 3.6 cm
• Input voltage: 4.5 to 9 Vdc
• Maximum current draw: 10 mA

What’s in the box:

• 1 x PCB Board
• 3 x 2N3904 transistors
• 8 x resistors
• 2 x diodes
• 3 x capacitors
• 1 x LED
• 2 x Three pin connector
• Ten page assembly and how it works manual

NOTE: This is a kit that requires basic soldering skills.