Count-Down Timer - Relay Output Switch
Since timer kits are extremely in hobby kit builder circles - we just had to satisfy the urge of the community! The 555 timer IC is perhaps the single most popular way of making timer circuits - so we used that too!
This circuit uses the 555 counter IC as the timer, and two transistors in order to switch the relay-switch to either ON or OFF, depending on a user-selected jumper setting. There are also jumpers which all the constructor to select the the countdown time value - from 8 - 8192 seconds (about 2 hours 15 minutes).
The circuit primarily consists of 3 parts: an oscillator, a ripple counter and two switching transistors.
Count-Down Timer - Relay Output Switch Reviews: