12 VDC to -12 VDC converter circuit with a 555 IC.
This 12 VDC to -12 VDC converter circuit gives -12VDC (negative 12 volts) from a power source of + 12VDC (positive 12 volts), with very few components.
Apr 162018
Apr 162018
Temperature gauge circuit using the LM324 IC
The temperature level is displayed using 4 LEDs:
A green LED indicates that the temperature is OK.
Two yellow LEDs indicate that the temperature is higher than normal.
A red LED indicates that the temperature is very high
Apr 122018
12V to 9V DC Converter Circuit Diagram (PCB)
This 12V to 9V DC converter is very useful for powering 9V DC devices in a car that uses 12V DC battery. The maximum current consumption allowed by this circuit is 0.8 amps.
Apr 102018
This simple alarm with thermostats circuit can be used on places where we must detect overheating. It uses 3 thermostats, and a one, 2 contact, relay
Apr 052018
12V Auto turn-off battery charger
This 12V auto turn-off battery charger automatically disconnects from mains to stop charging when the batteries are fully charged. It serves to charge the battery of our car, using the 120/240 VAC
Apr 042018
Transformerless Power Supply Circuit We will use a zener diode among other elements to acheive the Transformerless Power Supply circuit. This means that our power supply will give a limited range current value (it will be a maximum and a minimum posible current that the power supply circuit can deliver). This power suply must be permanently connected to the circuit as a whole […]
Apr 032018
Refrigerator door alarm circuit with two 555 timers
This refrigerator door alarm circuit alerts you when the door has been left open. Very important, because the power consumption increases when this happends. It uses the popular 555 timer IC
Apr 022018
NAND gate using transistors
This NAND gate using transistors circuit simulates the operation of a two or more inputs NAND gate. (There is a diode for each input. D1, D2, …)
Mar 282018
Car battery monitor circuit using 4 LEDs
This simple Car battery monitor, allow us to know the voltage of the battery at all times. To achieve this 4 leds are placed somewhere on the dash of the car. Each LED has a label indicating the battery voltage at that time.
Mar 272018
TRIAC. Power control on alternating current (AC)
Triac is a semiconductor device that belongs to the family of thyristor control devices. It is essentially two SCR connected in parallel and backwards, sharing the same gate.
Mar 262018
8 LED VU meter made of IC-LM324.
This circuit can be used to display the variation of an audio signal in a group of 8 LEDs, behaving like a VU meter. We could use an specific integrated circuit used for VU meters, but we decided to use a readily available integrated circuit: The LM324 op amp.
Mar 252018
OR and AND logic gates made with diodes
The Diode Logic uses the fact that the diodes conduct only in one direction. (they behave like switches)