nº950

Audio amplifier driving piezoelectric loudspeaker is turned on and off by knocking on the piezoelectric loudspeaker, supply 12V

nº949

Doorbell with piezoelectric loudspeaker which has two functions: doorbell button and tone reproduction, supply 12V

nº948

Sinewave led sequence with memory effect, supply 9V

nº947

Led triangle with line-by-line filling is controlled by 1 bipolar transistor, supply 9V

nº946

Ear replacement for in-ear earphones tester, supply 2xNiMH

nº945

Simple "joules thief" driving RGB led with 1 bipolar transistor has 6 operating modes: permanent R, G, B or blinking R, G, B; supply 1xNiMH.

nº944

Audio link with decorative mini incandescent lamp