Parameters of Nonlinear Delayed Circuit

This is a design schematic circuit diagram for parameters of nonlinear delayed circuit. This circuit is based on LM 324 as brain of the controller. The nonlinearity is built up of the transistor T 1 , the adjustable amplifier OA 1 and the resistors R 2-R 7. Electronic components: delay line: bucket brigade line MN 3011 with 3328 stages, triggered by MN 3101 (both National Panasonic); OA 1 :LM 324N; C = 660 pF; R 1 = 470 k,R 2 = 100 k lin., R 3 = 22 k, R 4 = 4.7k,R 5 = 10 k,R 6 = 1k,R 7 = 47 k;T 1 BC 238C. This the figure of the circuit schematic.

The Time Delay Circuit

This is a simple circuit for the time delay circuit. This circuit is based on transistor as controller the circuit. This is the figure of the circuit;

The length of time the circuit stays on for depends on how long it takes for the stored electrical current to leak back into the circuit, keeping the transistor (and thus the entire circuit) energized. We have a resistor that is limiting the rate at which the capacitor can discharge. If we increase the value of that resistor, it will take the capacitor longer to discharge and so the cold starting circuit will stay energized for longer. Likewise, if we decrease the value of the resistor, the capacitor will discharge more quickly, and the circuit will operate for a shorter period of time.

Cascaded Timer using 4528 IC

This is a simple design circuit that uses a CMOS dual re-trigger mono stable IC 4528 in a cascade timer circuit. The CMOS timer can be easily cascaded with other similar 4528 circuits to lengthen the timing needed. This is the figure of the circuit.


The timing of the project is determine by VR3 and C1 for the first stage and VR4 and C2 for the second stage. Once button S1 is pressed, the 1st stage output pin 6 logic level will go high and output pin 7 will go low for the preset time which is determined by VR3 and C1. When the time is up, the output pin 6 will go low and pin 7 high. At this moment of time, pin 7 will positive trigger the 2nd stage of the timer at pin 12. Output pin 10 will go high and pin 9 will go low for a time determine by VR4 and C2 before the cycle end with pin 10 back to low and pin 9 to high.

Counter Down Timer Circuit

This circuit is design of the counter timer that using countdown calculation. This circuit is using 555 IC as main control. 555 IC is a counter IC and a transistor switch to activate a relay either ON/OFF (mode selected by a jumper) as soon as the counting period is over. The circuit consists of an oscillator, a ripple counter and two switching transistors. This is the figure of the project circuit.


The 555 is configured in the standard astable oscillator circuit designed to give a square wave cycle at a period of around 1 cycle/sec. The output pulse from pin 3 of the 555 is fed to the clock input pin 10 of the 14-stage binary ripple counter, the 4020 (or 14020.) Operation of the circuit is explained in next. In this circuit C3, R4 and D1 are arranged as a power-on reset. When power is applied to the circuit C3 is in a discharged state so pin 11 will be pulled high. C3 will quickly charge via R4 and the level at pin 11 falls thus enabling the counter. The 14020 then counts clock pulses until the selected counter output goes high. D1 provides a discharge path for C3 when the power is disconnected. You can change the components values of R1 and C1 to set the 555 count frequency to more than 1.0 Hz. If you change the count to 10 seconds then a maximum timer delay of 81920 seconds, or 22.7 hours, can be obtained.

The output from the 4020 goes to a transistor switch arrangement. Two BC547 are connected so that either switching option for the relay is available. A jumper sets the option. The relay can turn ON when power and counting start then turn OFF after the count period, or it can do the opposite. The relay will turn ON after the end of the count period and stay on so long as power is supplied to the circuit. Note that the reset pin of the 555 is connected to the collector of Q1. This enables the 555 during the counting as the collector of Q1 is pulled low.

Digital Stop Watch Using NE555 Timer IC

This is s design of digital stop watch circuit that built around timer IC LM555 and 4-digit counter IC MM74C926 with multiplexed 7-segment LED display. This is the figure of the circuit.


MM74C926 consists of a 4-digit counter, an internal output latch, NPN output sourcing drivers for common cathode, 7-segment display and an internal multiplexing circuitry with four multiplexing outputs. The counter advances on negative edge of the clock. The clock is generated by timer IC LM555. The circuit works off a 5V power supply. It can be easily assembled on a general-purpose PCB. Enclose the circuit in a metal box with provisions for four 7-segment displays, rotary switch S1, start/stop switch S2 and reset switch S3.

For operation this circuit is explanation in the next. First, reset the circuit by pressing S3 so that the display shows ‘0000.’ Now open switch S2 for the stop watch to start counting the time. If you want to stop the clock, close S2. Rotary switch S1 is used to select the different time periods at the output of the unstable multi vibrator (IC1). This circuit is powered by 5V DC. That power supply can take from regulator power supply. You can read in this site about the regulator that can be used.