nº965

 

Siren with 3 transistors, supply 12V

nº964

 

Simple whistling detector based on LM567, supply 6V

nº963

 

Simple alarm triggered by interrupting wire loop. 7 pcba components( 3 transistors + 2 resistors + 2 capacitors). Standby current consumption less than 1uA; supply 12V( 8xAA or AAA)

nº962

 

"Knight rider" led sequencer with 10 red leds driven by 1 transistor; supply 12V

nº961

 

1 led voltmeter(0-10V). The number of led flashes is the same as the number of  volts present at circuit input. After counting cycle the led turns off longer and the counting cycle is restarted; supply 12V.

nº960

 

White led luminous intensity controlled by single tact-switch. Up/Down loop variation discrete or continuous. Uses only one LM324 Quad opamp integrated circuit, supply 5V.

nº959

 

Simple RC low pass filter for measuring stand-by DC current consumption of devices having pulsed currents. Time constant adjustable from 0.6s to 30s.

nº958

 

Minimalist MW experimental regenerative radio receiver. Only ferrite rod antenna; 1 transistor; audio output with 32+32ohm common earphones; no tickler coil; supply 2xNiMH. Can satisfactory  tune during daylight to AM broadcast station disted about 30Km from 50kW transmitter. 

nº957

 

Super-regen radio receiver for the FM band with audio amplifier KA2212, supply 5V

nº956

 

Experimental short range RF doorbell for FM radio receiver. Two transistors, 40cm wire antenna, supply 9V

nº955

 

Simple regenerative AM receiver for the MW band: 1 darlington transistor / loudspeaker volume / requires extra 1,5mts wire antenna / no tickler coil ( the ferrite rod antenna assy has impedance matching coil, however it is not used in this case) / no earth connection / supply 5V or  9V.

nº954

 

Prototype of clap lamp switch for lamps having E27 holder, supply 230Vac/50Hz

nº953

 

Experimental TRF regenerative MW receiver with 1 transistor; audio output by piezoelectric speaker, 10mts wire antenna + PE connection, supply 9V.

nº952

 

Simple MW reflex radio using audio amplifier KA2212, supply 9V

nº951

 

Simple MW reflex radio based on audio amplifier TDA1013B, supply 12V

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