nº1001

 

Proximity detector with one transistor, supply 2xR03

nº1000

 

Square root(1)

Square root (0,81)

Square root (2)

Voltage square root extractor; about 60mV remaining error; supply +/-5V_USB

nº999

 

Powerbank stand-by mode disabler. Many powerbanks will enter in stand-by mode when load current drops bellow a threshold level ranging from microamps up to about 50mA. Others will start hiccup its output voltage. A simple circuit with 2 transistors will prevent stand-by mode at the expense of only a few microamps.

nº998

 

Simple thermometer with silicon diode sensor can measure outdoor temperatures ranging from -50ºC up to +50ºC, supply 9V

nº997

 

The simplest capacitance meter for electrolytic capacitors with indirect reading, supply 1,5V

nº996

Minimalist led chaser with 2 modes: tact-switch short press runs led ring oscillator; tact-switch long press runs inverted led chaser; supply 3V

 

nº995

 

Reaction time measuring. By pressing COUNTING tact switch a new test is started. The middle tact switch should be pressed as soon as GO red led turns on; waiting time is variable and cannot be predicted; digital voltmeter displays reaction time. (1mS per mV). Pressing RESET tact switch erases current reading for new test; supply +5V_USB

nº994

 

Heads or tails game with 2 mini incandescent lamps, supply +5V_USB

nº993

 

Random flashing led bar; individual stages controlled by SCR, supply 24V

nº992

 

Incandescent lamp flashes controlled by 1 optocoupler, supply +5V_USB

nº991

 

Bicolor led flashes controlled by 1 optocoupler, supply +5V_USB

nº990

 

Simple potentiometer tester with 3 transistors: 2 leds OFF: ok / 2 leds ON: defective wiper / 1 led ON: defective resistence element / Suitable for any resistance value; also tests sliding noise; supply 2xR03

nº989

Symmetrical astable multivibrator with two supply voltages. 

nº988

 

Simple transistor astable multivibrator with f_max/f_min>200, supply 230Vac/50Hz

nº987

 

Mains supplied roof light is turned-on only by fast switching action on the wall switch. As there is no need for extra stand-by power, the module can be integrated in a E27 lamp holder adapter unit.

nº986

 

Ultrasonic detector using standard electret condenser microphone. Conversion to audible range is achieved by frequency mixing with local oscillator, supply 3V

nº985

 

nº984

 

Analog capacitance meter 10nF-2200uF, supply 3V

nº983

 

"knight rider" with 10 leds, controlled by 1 bipolar transistor, supply 5V 

nº982

 

Led bar with 8 white leds, controlled by 1 transistor, supply 9V

nº981

 

Sensitive regenerative receiver for MW band (550kHz-1,65MHz) with 1 transistor; uses standard low impedance earphones (32+32 ohm), supply 3V.

nº980

 

1 transistor AM band regenerative receiver,loudspeaker output, supply 9V

nº979

 

Alternative dimmer without capacitors and trigger diode; 2 power control ranges: 25%-50% and 50%-100%; supply 230Vac/50Hz

nº978

 

Light activated red led astable multivibrator can be triggered at long distance by laser beam, supply 1xLi-ion cell

nº977

Breathing knight rider sequencer, 10 leds, 3 transistors, supply 12V

 

nº976

 

Mains supplied wheel of fortune with 6 dual leds.