Are you interested in building basic logic circuits and eventually even an entire computer just using just transistors?

If so, you’ve found the right home!

Our mission is to provide inexpensive kits and tutorials to help people build and understand simple and more complicated logic circuits. Our circuits are modular allowing circuits to be connected together in different ways. For now we have two starting modules but more will follow in the future.

We currently support the following kits:

PRODUCT 1 – Debouncer Kit – $4.95

Description:
 A debouncer is used in a circuit to guarantee a single, consistent contact (on) for the switch. This ensures no ‘bouncing’ of signal which can confuse an electronic circuit.

At first glance it might seem that when the switch is depressed, contact is made in one action. This isn’t usually the case. Because the switch is made from metal parts which have a degree of springiness about them, when a switch closes it can momentarily bounce rapidly back and forth before settling down. This is called switch bounce. In many applications this doesn’t matter. If you’re using a switch to turn on a light, we don’t notice the bounce since it is so fast. If you are trying to control a digital circuit, the bounce can be very bad because the circuit that is connected to the switch will often interpret the bounce as a series of on/off changes and respond accordingly.  For example, a bounce can last between 10 and 300 µs. Note that a simple computer like an Arduino is capable of processing a few hundred instructions in that time. To the Arduino or any logic circuit, the bounce looks like a series of on/off input signals.

What’s in the box:

a) PCB Board
b) NE555 timer and socket
c) Two resistors
d) Three capacitors
e) Switch
f) Three pin connector
g) Eight page assembly and how it works manual

The board can be used in two ways: a) Plugged into a boardboard or b) as a stand alone board.

 

 

 

 

 

 

PURCHASE HERE

PRODUCT 2 – Bistable Multivibrator (flip-flop) Kit – $5.95

Description:  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. These circuits are also xometimes called flip-flops.  Such circuits are often used to store single bits of information where 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.

A circuit with two stable states can be made from two transistors, T1 and T2. In one state T1 will be conducting while T2 will be off. For the other stable state, T1 is off and T2 is conducting. As mention before, the state of the flip-flop is changed by input a trigger signal.  A full cycle of output is produced for every two trigger pulses.

What’s in the box:

a) PCB Board

b) Three 2N3904 transistors
c) 8 resistors
d) Two diodes
e) Three capacitors
f) One LED
f) 2 x Three pin connector
g) Ten page assembly and how it works manual

 

 

PURCHASE HERE

PRODUCT 3:  Full kit that includes four flip-flops to build a binary counter – $24.95

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 clock and a battery pack. 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).

 

 

 

 

 

 

 

Its possible to build a 4 but binary counter from a single TTL chip (7493) but thi schip is literally a black box and understanding in depth how it works is limited. Therefore we chose to provide a binary counter made from discrete transistors. 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 we provide a manual that includes a detailed explanation of how the circuit works including the role of every component in the circuit.

What’s in the box:

1. 4 x flip-flop units
2. 1 x debouncer
3. 1 x Clock (Variable frequency)
4. Battery pack (batteries not included)
5. 12 x Cables
6. Assembly and how it works manual

PURCHASE HERE

PRODUCT 4:  Breadboard Tactle Switches x 5- $4.95

This is a simple breadboard compatible tactile switch on a small PCB with header pins that can plug into a standard breadboard. With every order you’ll get a kit to make 5 tactile switches. Kits include boards, switches and header pins.

Why did you make it?

I was fed up with tactile switches popping off the breadboard just when I needed to press one. So I decided to make a small breadboard compatible tactile switch. This solves my popping off problem.

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

What’s in the box?

  • 5 x PCBs
  • 5 x Tactile switches
  • 10 x header pins

PURCHASE HERE

PRODUCT 5: NOT Logic Gate – $2.95 or $2.50 each for sets of four four kits

Description:  The kit supplies components to build a transistor based logical NOT gate with an indicator LED. The NOT gate design is similiar to that used in TTL circuits. The input pin connects to the emitter of a steering transistor which feeds an output transistor and LED indicator. The fan-out is good which enables the NOT gate to drive multiple other gates.

With just a couple of NOT gates it is surpising what one can do with them. The documentation describes how to make a simple flip-flop and and two different kinds of oscillator (feedback and relaxation) from a couple of NOT gates hooked up together.

 

 

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

Specification:

– Board Dimensions: 1 inch x 1.1 inches
– Input voltage: 4.5 to 9 Vdc depending on application
– Maximum current draw: 5 mA
– 3mm (M3) screw holes at the corners
– Pin connectors are spaced such that the board can be optionally plugged into a breadboard

 

 

What’s in the box?

– PCB Board
– Three 2N3904 transistors
– Four resistors
– One capacitor
– 2 x three pin connector
– 3 mm LED
– Eight page assembly and how it works manual

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

PURCHASE HERE

PRODUCT 6: NAND Logic Gate – $2.95 or $2.50 each for set of four kits

Description: This is a kit to teach how to use transitors to make logical gates. In this case the kit can be used to build a simple NAND gate. The NAND gate design is similiar to that used in TTL circuits. The input pins connect to the emitter of steering transistors which feed an output transistor and LED indicator. The fan-out is good which enables the NAND gate to drive multiple other gates.

 

The kits comes with 12 pages of documentation and describes how to build the circuit (for beginners), how the circuit works and a series of projects to that use NAND gates, including an XOR gate, flip-flop, half-adder, full-adder and a logic tester.

Note: This is a kit that requires soldering but is suitable for beginners.

 

 

 

Specification:

– Board Dimensions: 1 inch x 1.1 inches
– Input voltage: 4.5 to 9 Vdc depending on application
– Maximum current draw: 5-10 mA
– 3mm (M3) screw holes at the corners
– Pin connectors are spaced such that the board can be optionally plugged into a breadboard

 

 

What’s in the box?

– PCB Board
– Four 2N3904 transistors
– Four resistors
– One capacitor
– 1 x three pin connector
– 1 x for pin detector
– 3 mm LED
– 12 page assembly and how it works manual

PURCHASE HERE

PRODUCT 7: Transitor/NAND Half-Adder – 24.95

A half-adder is a digital circuit capable of summing two binary digits to form the sum, and a carry. For example, using binary notation a half-adder will compute the following binary relations:

0 + 0 = 0

1 + 0 = 1

0 + 1 = 1

 

While:

1 + 1 = 0 and a carry

That is a sum of zero and a carry of one. The half-adder forms the basic unit for building much larger and complex adding circuits and can be built from five NAND gates. The kits comes complete with all parts to build a fully functional half-adder. The only thing missing are four 1.5 v batteries. Parts include five NAND gates, jumper cables, breadboard, battery pack and two input switches to represent the binary inputs. Each NAND gate displays its state via a LED, it is therefore possible to easily get an idea of the state of all the gates simply by inspection.

The kit also comes with a detailed manual on how the individual gates operate, how the half-adder operates and full assembly instructions making it suitable for beginners. With two kits it is possible to make a full-adder (see manual).

Why did you make it?

I am interested in retro computing and having built a half-adder from elementary transistor gates. I thought it would be worth making it available as an educational kit.

What makes it special?

This kit will help users understand transistors, logic and simple binary addition in a single kit.

Specification:

  • NAND Gate Board Dimensions: 1 inch by 1.1 inches
  • Input voltage 4.5 to 9 Vdc
  • 3mm (M3) screw holes at the corners
  • Pin connectors are spaced such that the boards can be optionally plugged into a breadboard

What’s in the box?

  • PCB Board x 5
  • Four 2N3904 transistors x 5
  • Four resistors x 5
  • One capacitor x 5
  • 1 x three pin connector x 5
  • 1 x four pin connector x 5
  • 3 mm LED x 5
  • One breadboard
  • Two tactile switch kits
  • Two resistors for pull-down (yes pull-down) logic input
  • Jumper cables to make half-adder
  • Battery pack
  • Twelve page assembly and how it works manual

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