nº1018

20 green leds bidirectional bar, supply +5V_USB

 

nº1017

 

Minimalist phase-shift oscillator drives piezoelectric loudspeaker to make a simple buzzer, supply +5V_USB

nº1016

 

Minimalist phase-shift oscillator drives green led inserted in the feedback network, supply +5V_USB

nº1015

 

Squegging transistor negistor with blue led, 5 components, supply 12V

nº1014

 

Harvesting solar energy by 10 superbright 5mm yellow leds to run a low consumption led chaser. Although a small photovoltaic panel salvaged from an electronic calculator is being used in this demonstration, the leds themselves alone  will run the sequencer when the protoboard is exposed to direct sunlight. Superbright leds are required.

nº1013

 

Experimental reflex receiver for MW band with 2 transistors and 3V supply voltage is tuned by AM varicap diode BB212 having noiseless voltage supply generated by 4 photovoltaic couplers.

nº1012

 

Accurate USB power meter with 5 transistors. Maximum power about 400mW.

nº1011

 

Accurate analog computer with 3 bipolar transistors multiplies two DC voltages ranging Vx from 1V up to 5V and Vy from 0.1V up to 0.9V, supply +5V_USB

nº1010

 

Single capacitor symmetrical astable multivibrator, supply +5V_USB

nº1009

 

Minimalist transistor phase-shift oscillator with 7 components. Higher supply voltages allow very low frequency with low capacitor values, supply 24V

nº1008

 

The multimeter dancing needle, supply 3V

nº1007

 

Led chaser with 2 active blue leds changing the stop position, supply +5V_USB

nº1006

 

nº1005

 

Experimental regenerative radio receiver for MW with one transistor; loudspeaker volume, low impedance(32 Ohm) 40mm loudspeaker; random wire antenna with 5mts; mains PE connection; tuning broadcast radio station at 630kHz disted about 30km from 50kW transmitter; groundwave propagation; supply 2xR03. 

nº1004

 

Simple DC considerations about avalanche diode emulator.

nº1003

 

Dual led flasher, supply 230Vac 50Hz

nº1002

 

Mains supplied bicolor led flasher; Flash rate and led color are controlled by a single potmeter.

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.