Doorbell-controlled burglar deterrent light

One obvious, perfectly normal and socially accepted way of seeing if somebody is at home is to ring the doorbell. Unfortunately, burglars also employ the very same doorbell to see if you are not at home! This circuit, we hope, will trick potential burglars into believing that someone is about to answer the door by turning on a lamp after a short delay. The length of the delay is adjustable between about 5 and 125 seconds. Likewise, the ‘on’ time of the lamp is adjustable between 25 and 600 s.