What workshop doesn’t have an air compressor? From impact wrenches and orbital sanders to pneumatic chisels, the potential energy of compressed air can be utilised in a variety of ways. Commercially available compressors usually work with a supply pressure of 8 to 12 bar. If too much air is released from the tank quickly, the supply pressure can even fall below 5 bar. But how can I find out the available pressure on the system? Small pressure gauges on the compressed air connections can provide information, but these are difficult to read from a few meters away. For this reason, we decided to build a large digital 2×7-segment display that shows the actual pressure.