nº876

Combined led bar and sound effect with 1 transistor, supply 12V

nº875

Beep-Beep alarm with 1 NE555N, supply 4,5V

nº874

Bip-bip alarm with 1 NE555 timer, supply 5V

nº873

Minimalist buzzer with 1 NE555 timer + 1 resistor + 1 piezoelectric speaker, supply 5V

nº872

Simple 1 transistor red led bar with 2 operating modes: oscillating / permanently ON; supply 12V

nº871

Simple led ring oscillator with 7 stages, supply 230Vac/50Hz

nº870

Very low frequency oscillator with 1 transistor drives 12V/5W incandescent bulb with low value timing capacitors, supply 12V

nº869

Blinking mini incandescent lamp(3V) with 1 bipolar transistor, supply 1xNiMH

nº868

Minimalist mini incandescent lamp sequencer, supply 12V

nº867

Variable voltage divider

nº866

Up and down fading of 12V/5W incandescent lamp with 1 bipolar transistor, supply 12V

nº865

nº864

Mains supplied doorbell with 4 components is activated with smartphone led lantern.

nº863

Prototype of simple capacitance meter for oscilloscope. Measured capacitor is 68pF. Oscilloscope time base is 20uS/div.

nº862

Prototype of car turn light with 5 leds, supply 12V.

nº861

Experimental car turn light indicator with 5 yellow leds and 1 transistor, supply 12V.

nº860

Experimental LW/MW TRF audion receiver with 2 bipolar transistors and tuning with varicap diode, supply 9V.

nº859

Simple 12V/5V-100mA self-oscillating buck converter with 1 transistor (switch) and 1 optocoupler. (PWM control)

nº858

Simple BTL class A amplifier based on dual op-amp LM358N drives 110 Ohm loudspeaker with 1.1Vpp sinewave under 2xNiMH power supply.

nº857

Complete experimental MW radio receiver based on dual op-amp LM358N. Envelope detector wtih OA5 Ge diode, 2mts wire antenna + PE connection; supply 2xNiMH

nº856

Simple thermometer with 1 transistor + 1 resistor + 1 trimmer potmeter, supply 2xNiMH

nº855

USB dummy loads and micro-USB to standard USB A receptacle adapter. Suitable for connecting USB standard connector 1A dummy load to universal Qi 5W wireless receiver type A/B with micro-USB connector.

nº854

Constant current, adjustable(up to 1A) dummy load for Li-ion batteries. For 100% discharge from 4,2V downto 3V. Discharge current is 1mA per mV measured. Supply 9V. No current drift during discharge. Led off means stopped discharge.

nº853

Experimental board for simple lithium-ion battery capacity tester with constant current dummy load adjustable up to 500mA. supply 5V.

nº852

Li-ion/Lipo battery cell simple capacity tester:
- Discharges @1C for batteries up to 500mAh.
-Stops discharge @ 3V (led OFF).
- C=Id(mA)xT(h).

nº851

Method for transforming polar electrolytic capacitors into non-polar capacitor.

nº850

- Mains voltage detector, supply 1xNiMH.
- Detector de tensão de rede, alimentação 1xNiMH.

nº849

Lithium ion battery charge(4,20V)/discharge(3V) protection with 2 bipolar transistors. Supply >=5V.

nº848

The ferrite bead led torch with 8 white leds, supply 1xNiMH. Low component count.