Interactive electronics resource
4013 D-Type Flip-Flop Board Instructions
Build, understand and experiment with the 4013 D-Type Flip-Flop Board. This resource brings the original kit material into the current MitchElectronics format with the schematic, circuit explanation, component and PCB information, construction guidance, troubleshooting and practical ideas where available.
Introduction
Pre-learning – The Logic Gate Board
Before you learn how the 4013 D-Type Flip Flop Board works, you should first learn how the Logic Gate Board works as that kit covers the basics of logic. The Logic Gate Board kit also provides multiple logic chips in the 4000 series, demonstrating how these chips work and how some of the 4000 series share similar packages and configurations.
What is a latch?
In electronics, it can often be important to remember the state of a signal so that it can be recovered at a later date. For example, it may be necessary to read an analogue voltage and store the value for signal processing that itself can take a while (commonly found in sample and hold circuits). Another example of where remembering a signal can be important is in a digital control circuit that needs to remember if a button has been pressed (such as the delay in an alarm system).
In the case of digital circuits, a latch is a device that can be used to remember the state of a logic signal, acting as form of memory (CPU cache memory uses such latches). Once a signal has been latched into the latch, the original signal can be removed, and the latch will still retain the value that it saw.
Latches are asynchronous devices, meaning that they will remember a signal as soon as they are presented with one, and they have two different inputs for remember either a 1 or 0 (often called set and reset). Such latches also have two outputs; one representing the remembered bit, and the other being the opposite of the remembered bit.
As such, latches have two possible states that they can be in, and if a logical 1 is presented to the set input, the latch will switch on (and stay on), and if a logical 1 is presented to the reset input, the latch will switch off (and stay off).
What is a flip-flop?
Latches are a critical circuit for digital electronics, but they are rarely used on their own. This is because latches suffer from a few issues, with the two biggest issues being that they latch their data immediately, and that they require two separate inputs for controlling the state of the latch.
To fix this issue, most latches are made synchronous using a few additional components, utilising a clock input for setting and resetting the data, and a single data input to set the value of the latch. Such devices are called flip-flops, and they make up the foundation of modern digital systems.
Because flip-flops are clocked devices, changes on the data input are completely ignored by the flip-flop if the clock input remains low. It is only when the clock input rises from a 0 to a 1 that the data present on the input sets the state of the flip-flop.
As the data input is a single bit, it also makes storing information far easier, but it also allows for some rather interesting configurations. For example, if the inverting output is connected to the data input, each clock pulse causes the flip-flop to flip its state (called a toggle).
Schematic
How does the 4013 D-Type Flip-Flop board work?
The 4013 D-Type Flip Flop kit is designed to let you experiment with the famous 4013 IC, which incorporates two independent flip flops. Each of these flip-flops not only has two complementary outputs, a clock input, and data input, but also a set and reset input that can be used to force the state of the flip-flop to a particular value.
Even though the 4013 IC (which is a part of the 4000 series of logic devices), has two independent flip-flops, the kit only uses one of these flip-flops, with the other being entirely used. This is to keep the circuit simple and reduce the number of components on the PCB.
The board integrates a special switch, SW3, which allows for connecting the D input to the complementary output /Q, which will turn the flip-flop into a toggle latch. When in toggle mode, pushing the clock input, the internal state of the flip-flop will switch to the opposite value.
Try it yourself
Circuit simulation
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What you need
Component List
| Component | Quantity | PCB Reference |
|---|---|---|
| 14-DIP Socket | 1 | U1 |
| 4013 IC | 1 | U1 |
| 100nF Capacitor | 1 | C1 |
| 1K Resistor | 10 | R1 to R10 |
| 3mm Red LEDs | 6 | D1 to D6 |
| Tactile Switches | 4 | SW1, SW2, SW4, SW5 |
| SPST Switch | 1 | SW3 |
| PP3 Connector | 1 | BT1 |
| 4013 D-Type PCB | 1 | — |
Inspect the board
Interactive BOM
Board reference
PCB & assembly
The PCB silkscreen and component references should be checked against the component list before soldering each part.
Before applying power
- Check every component against its PCB reference.
- Confirm the orientation of all polarised components and ICs.
- Inspect for solder bridges, unsoldered pads and clipped leads that could cause a short.
- Check that no loose wire or solder debris remains on the board.
Build with confidence
Construction tips
Recommended build order
A reliable way to assemble 4013 D-Type Flip-Flop Board is to work from the lowest-profile components to the tallest. This keeps the PCB easy to access while you solder.
- Fit resistors, links and other low-profile components first.
- Fit small capacitors and diodes, checking polarity where applicable.
- Fit IC sockets and small semiconductors, observing the orientation markings.
- Fit larger capacitors, potentiometers, switches and other controls.
- Fit LEDs, connectors and the remaining taller components.
- Insert socketed ICs only after soldering around the socket is complete.
- Inspect every joint and check for solder bridges before applying power.
Electronics construction guidance
If you are new to kit construction, use the Soldering Guide alongside these instructions. Identify each component before fitting it and compare its reference with the component list and PCB silkscreen.
When it does not work
Troubleshooting
Nothing happens when power is applied
- Confirm the supply is connected to the correct input and with the correct polarity.
- Check that ICs, diodes, LEDs, transistors and electrolytic capacitors are fitted in the correct orientation.
- Compare component values and positions against the component list and PCB reference.
- Inspect for missed joints, dry joints and accidental solder bridges.
The circuit powers up but does not behave as expected
This kit is intended for clocked digital storage and flip-flop experimentation. If the output is stuck, unstable or outside the expected behaviour, use the schematic to trace the circuit a stage at a time rather than replacing several parts at once.
Check the components around the part of the circuit responsible for the output or timing first. A misplaced resistor, reversed semiconductor or poor connection can allow a circuit to power up while preventing it from operating correctly.
The circuit works intermittently
Intermittent behaviour is often caused by a marginal solder joint, a loose connector or a component lead that has not been fully soldered. Gently inspect the board with power removed and reflow any joint that looks dull, cracked or incomplete.
If the fault remains, compare the assembled board with the schematic and PCB reference one connection at a time.
Ready to test and experiment?
Use a signal generator to test how fast the logic circuits can respond to signals
Once the board is working, compare its behaviour with the schematic and the explanation above. Try changing only one input, control or permitted component value at a time so you can clearly see what effect that change has on the circuit.