Page 3 New Circuits

You're simulating a circuit, it requires several digital gates, but you don't have a mixed-mode simulator. What to do? One solution involves creating simplified versions of the logic functions. To do this, we look to the NMOS transistor implementation of logic gates where the transistor acts like a voltage-controlled switch. But, instead of the transistor, we'll use the SPICE switch. Just like the transistor, the switch is defined to turn ON when the input voltage goes HI...

LED Chaser

LED Chaser

General There are many 9V chaser circuits that seem to waste about 7V when driving LEDs that are only about 2V. This project is unique, because it uses only two inexpensive alkaline battery cells totaling 3V for power. Since most of the waste is eliminated, the cells last a long time...

Detection for trains on model railway

Detection for trains on model railway

This light valve can be used for example to detect trains on model railway or a lap counter at the close racing. D3 receives a constant stream of power built around T1. When the light beam from D3 to T3 is not interrupted, led T3 and T2 is the basis of practically grounded. T2 not conduct and the LED is not lit. When the beam is interrupted, spert T3 and T2 conducts and the LED will light. Of course listen to other things like LED control between plus and the collector of T2. Please note the maximum load of 100 mA. The supply voltage may be between 4.5 and 12 volts...

Infrared light trap circuit

Infrared light trap circuit

This infrared light valve has more parts, so it works better and more reliable for alarms. The circuit responds less ambient light. The light valve consists of a transmitter and a receiver. The transmitter consists of a NE 555 which provides pulses to the infrared LED (D1) are fed. The frequency of the pulses is set to P1. On the receiver side we see the photo transistor T1 receives the pulses from D1. The pulses through C4 to the positive input of op amp IC2 led. Between the output of IC2 and the minus input is an RC network that ensures the lowest at about 7.2 kHz amplitude issues. ..

Motor Control circuit II

Motor Control circuit II

This circuit is 12 volt motors and lights well regulated. The scheme operates with PWM (Pulse Width Modulation). By IC1, a 555 is a square wave generated by a controllable duty cycle. This means that the width of the pulse is changed. The 555 sends a FET, a BUZ11, the tax on and off switches. Because the FET switches only and not as adjustable resistance works, he burned almost no energy. Also has more torque at lower engine speeds. If the motor current greater than 2A is T1 with D3 (think of the insulation) to a heat sink to be confirmed. To 2A this is not necessary. ..

Delay Switch

Delay Switch

This switch allows the model train at such a station will automatically slow down. The train stands for a certain amount of time and then slowly pulls back. You do not own the train to stop. The relatively simple circuit works. P1 potentiometer for setting the waiting time, while turning to A caused a shorter waiting time and turn to B results in a longer waiting period. P2 is to set the brake and acceleratieweg. Here, too, turn to A results in faster acceleration and the train slows. ..

Delay switching for power amplifiers

Delay switching for power amplifiers

This delay can be used in power amplifiers, to prevent the fuses fail when the amplifier is turned on. The circuit is very simple with a relay which turned on when C2 and C3 are charged. If the relay has not been applied, the resistors used to control connected to feed. If after some time the relay attracts the bridge resistors. Watch out for your own safety when building this circuit. On the whole circuit is power. F1 should be the value of having the fuse that normally would be used...

Single to double power with CA3140

Single to double power with CA3140

Another circuit for a balanced diet from a single voltage network. In fact, this is a uitbreding the other voltage divider circuit using a some power darling tons as buffer. This buffer can deliver a 200 to 300 mA...

Constant LED power circuit

Constant LED power circuit

An LED is usually a series resistor needed to ensure that the LED does not get too much power. The disadvantage of such resistance is that the current through the LED and thus the brightness changes as the voltage changes. This circuit prevents, through independent of voltage, constant current through the LED control. The circuit uses two transistors and two resistors. The circuit can be connected to voltages from 5 to 24 V...

LED Battery indicator

LED Battery indicator

This battery allows the indicator to the car battery voltage monitor. The indicator has four LEDs which indicate power. The more LEDs, the higher the voltage. The last LED is a flashing LED. It comes on when the accuspaning limit of about 15 V limit. This is a sign that something is wrong with the alternator or voltage regulator. The other LEDs light up in 9 V (D5: bad battery), 11 V (D7: battery doubtful) and 13 V (D9: battery ok). Build the circuit and verify the above activation points. If the measured values ??much different from the above, try other Zener diodes. Of 300 mW Zener are sufficient for the circuit...

Basic power supply schematic

Basic power supply schematic

The simplest power supply voltage regulator can be created with the 78xx series. The voltage regulator is available in different voltages (see table). The controller is 100 mA, 1 or 2 A provides. C2 is a decoupling capacitor. He must therefore as close to the controller are placed. The parts must be adapted to the supply voltage and current. At low voltages (below 5 V) can be reduced to C1 1000 uF. At voltages above 15 V and 1 A should be C1 4700 uF. With output currents above 1 A, the diodes are replaced by 1N5401. ..

5 A stabilized power supply

5 A stabilized power supply

This is a simple but powerful nutrition that less than 5 A can deliver. The circuit works by using a normal type 78xx voltage regulator and a buffer transistor. When the output current over 200 mA, then take over the T1, which limits the maximum output current is 5 Amps. The 1978 series regulator is available from 5 to 24 volts. In the place of the xx is the voltage, so 7812 for a 12 volt regulator. Take the AC in 5% higher than the desired output voltage. In that case, one under the wrinkle. MJ is a T1 (E) in 2955. This higher output currents must be well chilled. ..

10A stabilized power supply

10A stabilized power supply

This is a heavy diet, which can deliver 10A stabilized. The circuit is built around a normal 78xx controller, but for extra power equipped with T1. For the 78xx can be taken any type. Keep in mind that the input voltage of 3V regulator must be higher as the output nected. See 78xx power for the available controllers. T1 must be a large heat sink mounted when large capacities are diminished. A negative variant of this diet is here to find. ..

Fuse tester with LEDs

Fuse tester with LEDs

This indicator shows through a dual-LED see if a fuse is intact. The module is designed for 230 V AC. The green LED illuminates when the fuse is still good, the red lights when the fuse is broken. Perhaps the circuit to adjust for other voltages by changing the value of R1...

Wien bridge oscillator schematic

Wien bridge oscillator schematic

This is a simple scheme for whom a bridge oscillator. It provides a nice sinusoidal signal. This type of oscillator uses an op-amp. The weakening of the oscillating member (R1.. .. R2 C1 + C2) is 3x. To compensate, the attenuated signal strengthened.From shall be 3 times the opamp with feedback. To start the oscillation, in the early strengthening higher. Once a certain voltage is reached, the diodes conduct. This will reinforce 3 so that it is not too heavy and not uitdempt sine waves will make. ..