Power Off Time Delay Relay | Electronic Project Circuits

Posts Tagged ‘power off time delay relay’

Auto Power Off

We are surrounded by battery operated equipment of all kinds, and this array is growing still. Manufacturers and designers lean over backwards to make sure that their equipment draws a small current and can thus be operated by a battery. This has its flip side, too. because even if the equipment in question draws only a small current, when it is not switched off, the battery is flat after a few days or weeks. The circuit presented here can prevent this happening. It may be added to all kinds of equipment operating from a 9 V battery and switches this off automatically one minute after a preset time has elapsed. The peak switching current is 20 mA, which is more than enough for most applications.
The switch is formed by a p-n-p darlington, T1, which is actuated by push-button switch S1. The very high amplification of the darlington enables it to be kept on fairly long with the aid of a relatively small-value capacitor, C1 (= 100 µF). Resistor R3 limits the charging current of C1 to ensure a long life of S1. Resistors R1 and R2, in conjunction with C1, determine the switch-on time. When this time has elapsed, R1 ensures that T1 is switched off. Since the darlington can handle a UBE of –10 V, a polarity protection diode is not needed.
Author:H. Bonekamp
Copyright: Elektor ELectronics
Read more:http://www.extremecircuits.net/2010/07/auto-power-off.html

Be the first to comment - What do you think? Posted by admin - February 21, 2011 at 9:38 pm

Categories: Electronic Control Tags: power off time delay relay

Switch off delay circuit by 2N4871

This circuit prevents surges. From the opening – is switched off or power failure. The damage to electrical appliances. The circuit will switch to use a short period before Power raising circuit to go.
When raising the power supply 9-volt circuit then. Circuit delay. The duration of charging C1. VR1 is adjusted with time.When C1 is fully charged, it will be pressure to bias the pin G of the FET 2N4871 . Q1 to conduct work to trigger to pin G of the SCR to run.When SCR relay will work to cut the flow circuit to work. If you want to delay it longer, add the C1.

Be the first to comment - What do you think? Posted by admin - October 26, 2010 at 7:36 am

Categories: Electronic Control, Security Tags: power off time delay relay, Surge protector

One Button On Off Switch by 4093 and IRFZ44

The load is driven by the MOSFET IRFZ44 and 4093 AND gates are used in the circuit. The output of the 4093 IC drives the MOSFET. Only one button allows you to change the on-off state of the electronic circuits in which you use this switch. The circuit schematics is above. Click image to see the larger schematics diagram.