Jumperless Breadboard Offers New Spin on Old Tech

The breadboard is a classic tool any electrical engineering student is familiar with. Despite its shortcomings such as high parasitic capacitance and high resistance, it offers a quick and simple way to prototype electronic circuits without the need for soldering or creating PCBs. Analog circuits, digital circuits, and embedded systems can all be quickly prototyped, allowing a user to test out various connections and component values before committing to a final design. For a more modern spin on the breadboard Kevin Santo Cappuccio has put together a new revision of his jumperless breadboard design.

The jumperless breadboard achieves connections by utilizing 12 analog crosspoint switches mounted beneath the PCB. The switches are CH446Q 8x16 analog switch matrices that are connected such that any two points on the breadboard can be connected together. Any point on the breadboard can also be connected to any of the pins on the Arduino Nano at the top of the PCB. What's more, the jumperless breadboard is equipped with RGB LEDs underneath each row of breadboard connections that can be used to help show what is going on in the circuit. For example, rows can be lit up where connections are made or the colors can be used to display voltage or current sensing information.

Power can be provided onboard, which is derived from the USB output and is switchable between +/-8V, +5V, and +3.3V. An additional feature is also digital to analog converters (DACs). The second revision of the design uses MCP4728 12-bit I2C DAC which can output clean waveforms up to 100Hz. However, the third iteration of the design will feature a higher speed MCP4822 SPI DAC which can output clean waveforms up to 400KHz.

Currently, the best method of controlling the device and making connections is by using Wokwi software in combination with a bridge app. In doing so connections can be made in the software that automatically get applied to the breadboard. There are also plans to develop an Arduino library to make applying voltages and measuring signals simpler as well as a Python module that will offer similar features. While an Arduino Nano is included for additional control, the jumperless breadboard itself is driven by an RP2040 microcontroller. The firmware is still under active development and the entire project is open source.

Although the jumperless breadboard does offer a lot of features to be excited about there are a couple of trade-offs to be aware of. First, the switches have an ON resistance of approximately 75 Ohms. Thus, any connection made that is “jumperless” will have a series resistance of 75 Ohms. It is worth noting this is not critical in most breadboard designs and can actually act as a current limit and help keep a user from completely destroying a device. Furthermore, the switches also have rated current limits of 15mA per connection and 100mA per chip. Despite a couple drawbacks, the features still make this device worth considering for your next breadboard project.