Time Delay | Electronic Project Circuits

Posts Tagged ‘Time Delay’

Safety Guard by CD4060

Simple unit, Protects home appliances from voltage spikes
Protect your home appliances from voltage spikes with this simple time delay circuit. Whenever power to the appliances is switched on or resumes after mains failure, the oscillator starts oscillating and D5 blinks. This continues for three minutes. After that, Q14 output of IC CD4060 goes high to trigger the gate of the SCR through D4. At this moment, the voltage is available at the cathode of the SCR, which energizes the relay coil to activate the appliance and D6 glows. Switch SW1 is used for quick start without waiting for delay.

Circuit Operation:
At the heart of the circuit is IC CD4060, which consists of two inverter gates for clock generation and a 14-bit binary ripple counter. Here the clock oscillations are governed by resistor R1 and capacitor C1. In this circuit, only two outputs of the IC (Q5 and Q14) have been used. Q5 is connected to an LED (D5) and Q14 is used to trigger the gate of the SCR through D4 as well as reset the counter. The anode of the SCR is connected to +9V and the cathode is connected to the relay coil. The other pin of the relay coil is connected to the negative supply, while its contacts are used for switching on the appliances.
Source : electronicsforu.com

Be the first to comment - What do you think? Posted by admin - March 6, 2011 at 10:49 pm

Categories: Alarm systems, Detector Tags: CD4060, security circuits, Time Delay

Handy Time Delay With Relay Output

This circuit is designed to provide delayed relay switching action at power on. The delay is a function of the time constant produced by the combination of R1 and C1. At power on, C1 charges slowly via R1 and the coil of the relay. When the voltage across C1 exceeds both the base-emitter voltage of Q1 and the gate trigger voltage of the SCR, gate current flows. This fires the SCR and switches on the relay. At power off, diode D1 rapidly discharges C1 through the 100O resistor, so ensuring that every time the circuit is restarted, as in a temporary outage, the delay time is maintained.

Just about any NPN transistor can be used for Q1, since after SCR1 fires, it is effectively out of the circuit. In fact, the only part that’s still active after SCR1 turns on is the relay. You can’t get much simpler than that! This circuit can be used to delay speaker turn-on, so avoiding the “thump” that occurs in some stereo systems at power on. A 5-second delay is enough for this application, requiring approximately 560kO for R1 and 10µF for C1. Another application might be as a motor protector in a short power outage.
Author: R. Besana – Copyright: Silicon Chip Electronics

link : http://www.extremecircuits.net/2010/06/handy-time-delay-with-relay-output_17.html

Be the first to comment - What do you think? Posted by admin - January 4, 2011 at 1:42 am

Categories: Electronic Control, Timer Tags: basic timer, Time Delay, timer relay

10 minute time delay by fet 2N3819

This circuit is a basic function of the FET 2N3819, which acts as a switch. In the conduction and not conduction. It runs contrary to the transistor. The circuit can be used to delay the cycle is small. Such as delay, 9-volt light bulb, or motor delay to any DC 9 volts.
When raising the power supply circuit FET Q1 is running. D and S stand by the legs of furniture to the Tong Q1 will flow together, current flows through R2, so the flow from the legs through the leg and S. D, and through R4 to ground. So no current flows into R3 to transistor Q2 does not conduct. Resulting in a voltage appearing at the output is 12 volt, but when I press the S1 switch current flows into the capacitor C1 fully. Then go to the legs G of the FET. Q1 stopped working. Therefore, the current flowing through R2 is flowing to the R3 instead, and to bias transistor Q2 to work on the output transistor Q2 is not working out for 10 minute, because C1 is discharged. The S2 is the reset switch. By acting shock C1 to discharge out soon. That the time delay depends on the C1. If it will delay much longer, if less it will have less delay.