LM555 Timer with 12V Relay Kit by NightFire Electronics

This is the Timer with Relay Kit. This circuit is designed to turn on a Relay for a definite time period up to a few minutes (capacitor determined)and then the Relay will automatically turn off. The circuit is based on the LM555 Precision Timer that is triggered by a momentary switch contact. The switch may be a physical switch or it may be the output of other circuitry. There is also an on-board LED to indicate when the Relay is energized. A normally-open switch is required for the Trigger. When the switch is open or not made, the Relay circuit is OFF and the Relay outputs are with the Com connected to the NC (Normally Connected) pin. When the Trigger input is momentarily connected to Ground, the Timer circuit will output a single pulse which will turn on the Relay for a certain time. This time is adjustable from a few seconds to a few minutes or more. The circuit timing values may be increased to lengthen the time. The Relay contacts will switch to Com connected to NO (Normally Open). After the time period is over, the Relay will turn back off. Once the Timer is triggered, additional trigger pulses will be ignored for the duration of the Timer pulse. The Relay is an 833H series or JS1 Series SPDT relay with Form 1C contacts rated for 7 Amps @ 250VAC. The coil voltage is dependent on what version you get. This version has the 12v Coil. The Relay contacts are available as .250\" quick disconnect Faston connectors. The available contacts are the Common, NO (Normally Open) and NC (Normally Closed). This means that the circuit can either turn a device ON for a set time period or turn a device OFF for a set time period. This kits is also offered as a "Built & Tested" for those that do not want to build the kit themselves. The PCB is double-sided, plated thru-holes, 1.50\" long x 2.50\" wide made of .062\" FR-4 epoxy glass with 1-oz copper. It has green Solder Mask (LPI) on both sides with white Silk Screen on the Top side. It includes four mounting holes. The PCB traces for the Relay outputs are extra-wide on Top and Bottom sides for current-carrying capabilities. This kit does not include the tools you will need to assemble the circuit. You will need tools such as a soldering iron, solder, wire cutters, etc.