Simple Timer Power Circuit On Relay Project

This is a circuit diagram for power-on time delay relay circuit that takes advantage of the emitter/base breakdown voltage of an ordinary bi-polar transistor. The reverse connected emitter/base junction of a 2N3904 transistor is used as an 8 volt zener diode which creates a higher turn-on voltage for the Darlington connected transistor pair. This is the figure of the circuit.


Most any bi-polar transistor may be used, but the zener voltage will vary from about 6 to 9 volts depending on the particular transistor used. Time delay is roughly 7 seconds using a 47K resistor and 100uF capacitor and can be reduced by reducing the R or C values.

Simple Photo Detector Circuit Using BP103 Phototransistor Siemens

This is a design circuit that can be used to create a detection system with reference to the source of light energy. This circuit is based on BP103. This is a Silicon NPN phototransistor circuits used to control and training, industrial electronics, forks, and controlled by a computer flashes with its features such as high linearity, suitable for applications from 420N to 1130nm and packaged into the motherboard 18-lens transparent epoxy resin in combination with Database. This is the figure of the circuit.


During the operation, the circuit is producing low power, which is enough light detectors receives light. Even in the darkness, the light source can also be made from a variety of ways. Compatibility between the outputs of a TTL level logic produces a low level. This occurs because the light is detected by phototransistor Q1 BP103. This model of the transistor is manufactured by Siemens. Phototransistor has a photodiode with internal gain and nothing more than a bipolar transistor in a transparent case so that the base-collector junction can be achieved by light. Photons base-collector junction produce electrons can be injected into the base. The current gain transistor amplifies the photodiode current.

Simple FET Cascade Video Amplifier

This is a simple design FET Cascade Video Amplifier circuit. This circuit has some features they are reduction of feedback to almost zero and very low input loading. This circuit is control by FET and this is the figure of the circuit.


This circuit uses 2N3823 because it has high Yfs and low capacitance. RL and load capacitance limits bandwidth of the amplifier.

Simple AM Radio Circuit Using Transistor

This is a one design for simple circuit of AM transmitter, where the AM transmitter using ceramic resonator / filter of 3.587 MHz is presented here. This circuit is based on the core to the operation of the transistor circuits. This circuit is based on transistor for operation the circuit. This is the figure of the circuit.


Resonators / filters such as the frequency of 5.5 MHz, 7 MHz and 10.7 MHz may also be used. Using a different frequency filters / resonators will involve corresponding variation in the value of inductor used in the oscillator tank circuit is connected to the collector of transistor T1. AF input for modulation is inserted in series with the emitter of transistor T1 (and resistor R4) using a transistor radio type audio transformer such as a driver on the circuit. Based on the figure, the modulated RF output is developed across the tank circuit which can be tuned to the resonance frequency of the filter / resonator with the help of gang condenser C7. Next two stages formed with low-noise RF transistors BF495 is, in fact, connected in parallel for amplification of modulated signal coupled from collector of transistor T1 to the base of the transistors T2 and T3. Combined output from the collector of T2 and T3 is to the antenna feed through 100pF capacitor C4. Circuits that can be easily collected in the general purpose PCB. Range from transmitter is expected to be one to two kilometers. Circuits that require regulated 9 volt power supply for operation.

Simple 6V to 12V Converter Circuit Using Transistor BC547-BD679

This is a design circuit for converter circuit. This circuit is based on transistor as controller the circuit. There are two types of transistor that is BC547 and BD679. This circuit is a simple design of converter or inverter. This is the figure of the circuit.


This inverter circuit can use to 800mA of 12V power supply with a 6V. For example could you 12V Car Accessories (UK turning into a 6V) Car. The circuit is simple, more than 75% efficiency and very helpful. By changing a few components you, you also change for different voltages. L 1 is a custom inductor wound with about 80 turns 0.5 mm magnet wire a ring around the core with an outer diameter of 40 mm. Different values of D3 can be used to obtain different output voltages from 0.6V to 30V is about. Note that at higher voltages, the circuit could perform just as well and can’t produce much electricity. You may need to use a larger C3 for higher voltages and / or higher currents.

Part of components
R1, R4 2 .2 K 1/4W Resistor
R2, R3 47K 1/4W Resistor
R5 1K 1/4W Resistor
R6 15K 1/4W Resistor
R7 33K 1/4W Resistor
R8 10K 1/4W Resistor
C1, C2 0.1uF Ceramic Disc Capacitor
C3 470uF 25V electrolytic capacitor
1N914 diode D1
D2 Diode 1N4004
D3 12V 400mW Zener Diode
Q1, Q2, Q4 BC547 NPN transistor
BD679 NPN transistor Q3