What is it?

Description: This kit includes four flip-flip units to allow you to build a 4-bit binary counter. Included with the kit is also a debouncer kit, a variable frequency NE555 based clock and a battery pack. Except for the batteries, you get everything you need to build what's in the image below (plus a debouncer switch for manual operation).

The four flip-flops are connected in sequence, power is provided from one side of the cascade and a clock or debouncer circuit is connected to the other side of the cascade.

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

Why did you make it?

I'm interesting in retro-computing and I thought I'd start by building a simple memory unit which morphed into a bistable multivibrator. Because I wanted to understand the operation of these circuits in some depth, I decided to build the flip-flop from transistors. Of course one can purchase a TTL chip that is a dedicated binary counter, eg the 7493 but these a literally black boxes and the ability to gain an in depth understanding is limited. There is a lot to learn about basic electronics and some interesting electronic trickery in building a flip-flop from discrete transistors. For those who are interested in understanding how circuits work, the flip-flop is a good example to understand. As part of the purchase I provide a manual that includes a detailed explanation of how the circuit works including the role of every component in the circuit.

Specification:

• Each flip-flop board Dimensions: 4.0 cm x 3.6 cm
• Input voltage: 4.5 to 9 Vdc
• Maximum current draw: 40 mA

What's in the box?

• Four flip-flop kits
• One 6 volt battery back (batteries not included)
• One NE555 based clock to drive the binary counter automatically
• One debouncer switch circuit for manual control of the counter
• Assembly instructions and explanation for how the circuit operates.

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