récepteur à ultrasons pour casque

There are many potential applications nowadays to justify the use of a noise level meter -for instance, monitoring the sound output at dances, discos etc. The unit described here was designed primarily to es-tablish the noise level produced by model engines. It has five switched ranges from 70 dB to 120 dB in 10 dB steps and is readable to½ dB. The prototype was found to be accurate to± 1 dB.