DC Motor Reversing Circuit

This is a design circuit for DC motor reversing circuit using non latching push button switches. Relays control forward, stop and reverse action, and the motor cannot be switched from forward to reverse unless the stop switch is pressed first. This is the figure of the circuit;

Assume that the motor is not running and that all relays are un-energized. When the forward button is pressed, a positive battery is applied via the NC contacts of B1 to the coil of relay RA/2. This will operate as the return path is via the NC contacts of D1. Relay RA/2 will operate. Contacts A1 maintain power to the relay even though the forward button is released. Contacts A2 apply power to the motor which will now run continuously in one direction. If now the reverse button is pressed, nothing happens because the positive supply for the switch is fed via the NC contact A1, which is now open because Relay RA/2 is energized. To Stop the motor the Stop switch is pressed, Relay D operates and its contact D1 breaks the power to relays A and B, (only Relay A is operated at the moment). If the reverse switch is now pressed and released. Relay B operates via NC contact A1 and NC contact D1. Contact B1 closes and maintains power so that the relay is now latched, even when the reverse switch is opened. Relay RC/2 will also be energized and latched. Contact B2 applies power to the motor but as contacts C1 and C2 have changed position, the motor will now run continuously in the opposite direction. Pressing the forward button has no effect as power to this switch is broken via the now open NC contact B1. If the stop button is now pressed. Relay D energizes, its contact D1 breaks power to relay B, which in turn breaks power to relay C via the NO contact of B1 and of course the motor will stop. All very easy. The capacitor across relay D is there to make sure that relay D will operate at least longer than the time relays A,B and C take to release.

Low Pass Filter Subwoofer Circuit Using TL062

This is a circuit for subwoofer circuit. This circuit is simple design that is based on TL IC. This is the figure of the circuit;

In the form it appears the theoretical circuit of filter. In first glance we see three different circuits that are mainly manufactured round two operational amplifiers. This circuits constitute mixed, amplifier with variable aid and a variable filter. The manufacture end needs a circuit of catering with operational tendency of catering equal with ±12. the operational amplifiers that constitute the active elements for this circuits of are double operational type as the TL082 and NE5532. The operational these amplifiers belong in a family provided with transistor of effect of field IFET in their entries. Each member of family allocates in their circuit bipolar transistor and effect of field. This circuits can function in his high tendency, because that they use transistor of high tendency. Also they have high honor of rhythm of elevation (slew rate), low current of polarization for the entries and are influenced little by the temperature. The operational these amplifiers have breadth of area unity gain bandwidth 3MHz. A other important element for their choice is the big reject of noise, when this exists in the line of catering.

Low Impedance Microphone Amplifier Circuit

This is a circuit for microphone amplifier for low impedance. This circuit is based on transistor for controller the circuit. This is the figure of the circuit;

This circuit is use with low impedance (~200 ohm) microphones. It will work with stabilized voltages between 6-30VDC. If you don't build the impedance adapter part with T1, you get a mic amp for higher impedance microphones. In this case, you should directly connect the signal to C7.

Part:
R1=15k
R2= 150k
R3= 2k2
R4= 820
R6= 10k
R7= 10k
P1= 1M
C1= 3k9
C2= 100u
C3= 22u
C4= 4u7
C5= 470u
C6= 10u
C7= 100n
C8= 47u UNIPOLAR
D1= 1N4148
U1= TL081
CN1= SIL6

Stabilizer Circuit

This is a circuit for high quality power supply with a continuously variable stabilized output adjustable at any value between 0 and 30VDC. The circuit also incorporates an electronic output current limiter that effectively controls the output current from a few milliamperes (2 mA) to the maximum output of three amperes that the circuit can deliver. This is the figure of the circuit;

This feature makes this power supply indispensable in the experimenters laboratory as it is possible to limit the current to the typical maximum that a circuit under test may require, and power it up then, without any fear that it may be damaged if something goes wrong. There is also a visual indication that the current limiter is in operation so that you can see at a glance that your circuit is exceeding or not its preset limits.

Free Switch Mode Pre-Regulator Circuit

This is a circuit for switch mode pre regulator circuit. The botheration was that a voltage regulator had to bead the 18 volt capital ability accumulation voltage to 8 volts at 500ma to ability the CD player, crumbling 5 watts of ability and causing a lot of calefaction central the bunched unit. This ambit acts as an interference-free pre-regulator to abundantly abate the ability loss. This is the figure of the circuit;

The achievement voltage of this ambit is artless by ability band fluctuations. Amount voltage aberration is alone abased on the on-resistance of Q2 and the amount of C2 (re: ripple). The achievement voltage can be set so that the ripple lulls are aloof aloft the drop-out voltage of the beeline regulator at best amount for best activity conservation. The college amount you aces for C2, the added activity you can save and the added abiding the pre-regulator’s achievement voltage.

FM Band Monaural Transmitter Circuit

This is a circuit for a high quality monaural FM transmitter is quite useful in a variety of applications. The audio from a TV or entertainment system may be transmitted for remote or portable listening and for wireless earphone listening. This is the figure of the circuit; 

The audio from an AM receiver placed near a window can be retransmitted within a metal building where AM reception is not possible. Two transmitters will convert two portable FM receivers into cordless stereo speakers for outdoor events. A keyboard may be played through the stereo without wires simply by tuning in the transmitter. A child will love an operational, miniature FM station complete with transmit "on the air" light. Simply connect the stereo's monaural output to the transmitter and transmit CDs, tapes, microphones, and other audio sources. Connect the transmitter to the computer's sound card and have big speaker sound. Even silence may be transmitted. Tune the transmitter to your favorite station and when the annoying commercial starts, simply flip on the power and silence.

Car Interior Light Extender Circuit

This is a circuit for a Courtesy Light Extender for cars. When a door is closed in a car, it extends the ON time, so the passenger can see where he/she is sitting. This is the figure of the circuit;

The light normally goes off immediately when door switch is opened, but the circuit takes over and allows current to flow because the 22u is not charged and the first BC 547 transistor is not turned ON. To illuminate the interior light, this turns on the second BC547 via the 100k and the BD679 is also turned. The 22u gradually charges via the 1M and the first BC547 turns on, robbing the second BC547 of “turn-on” voltage and it starts to turn off the BD679. When the door is opened, the 1N4148 discharges the 22u.

20VAC 60 Watt Sunrise Lamp Circuit

This is a circuit for a 120VAC lamp is slowly illuminated over a approximate 20 minute period. The bridge rectifier supplies 120 DC to the MOSFET and 60 watt lamp. A 6.2K, 5 watt resistor and zener diode is used to drop the voltage to 12 volts DC for the circuit power. The bridge rectifier should be rated at 200 volts and 5 amps or more. This is the figure of the circuit;

In operation, a 700 Hz triangle waveform is generated at pin 1 of the LM324 and a slow rising voltage is obtained at pin 8. These two signals are compared at pins 12 and 13 to produce a varying duty cycle rectangular waveform at pin 14, which controls the MOSFET and brightness of the 60 watt lamp. When power is applied, the lamp will start to illuminate within a minute or so, and will slowly brighten to full intensity in about 20 minutes. You can make that longer or shorter with adjustments to the 270K resistor at pin 9. The 2.2 ohm resistor and .015uF cap connected to the lamp serve to supress RFI. The diode at pin 9 and 10K resistor on pin 8 are used to discharge the 3300uF cap when power is removed. Power should be off for a few minutes before re-starting. This circuit is connected directly to the AC line and presents a hazard if any part is touched while connected to the line. Use caution and do not touch any parts while the circuit is connected to the AC line. You may want to use a 9 volt battery connected across the 12 volt zener to check the basic operation. The DC voltage at pins 1,2,3,5,6,7 will all be around 4.3 volts if the circuit is working correctly. If the DC voltages are all correct, you can use a variac to slowly apply the full line voltage and check for proper operation.

Voltage Doubler For Solar Battery Charger

This is a circuit for PV Solar Panels have typical voltages of 3, 6, 12, 24 Volts. This circuit can be built which will increase the voltage output from a solar panel so it can be used to directly power a device or to charge batteries. This is the figure of the circuit;


It is comprised of some very easy to source components. The key component is the NE555 timer IC - one of the most popular integrated circuits (ICs) of all time. In this circuit it is used to generate short pulses of DC electricity which are passed through a couple of diodes and capacitors which act to multiply the voltage. The maximum output current of a 555 timer is typically 200 mA and it can dissipate up to 600mW of power. Exceed these specifications and the chip may be destroyed. Click here for full typical NE555 Specifications.

Timer Circuit Using 4060B IC

This is a design circuit fir timer circuit that is based using 4060B. This is the figure of the circuit;


The pins labeled in red Q4-Q14 are the binary outputs: Q4 for the 16's, Q5 for the 32's, Q6 for the 64's and so on up to Q13 for the 8192's, and Q14 for the 16384's. Just three external components are required to control the 4060B counter - two resistors and one capacitor. The frequency of the internal oscillator (i.e. the speed of the count) is set according to the equation. Since Q14 represents the 16,384's and Q4 represents the 16's - we know it will take 1,024 times longer (16,384 / 16) for Q14 to flip from 0 to 1 than it takes Q4. So, for an example 2-hour timer (=7,200 seconds), we just need to fine-tune the circuit so that Q4 turns on after 7,200 / 1,024 seconds = 7.03 seconds, knowing that if that is done correctly, after exactly 2 hours Q14 will flip from 0 to 1.