Security & Surveillance
( See also "FM Transmitters", "Sirens & Sound", "Strobes & Flashers" )

K8 - Light Alarm Price Photo Docs
Detects very small amounts of light and sounds the piezo alarm. Put it in your cash box or cupboard. Uses Darlington photo transistor MEL12 and 14011 IC.

K13 - Sound Activated Tape Recorder Switch Price Photo
Can be adjusted to turn on your tape recorder through its REMOTE plug. Has feedback and delay circuit for robust operation. Very sensitive. Proven circuit. Needs 6V plug pack for most stable operation.

K20 - Crystal Locked Ultrasonic Movement Detector 1 Price Photo Docs
Matched 40 kHz transmitter/receiver pair of transducers detects movement at over 7 metres. Separate PCB for mounting the active units. Latch/reset PCB-mounted switch on board. Sensitivity control. 9V battery operation. Transmitter is crystal- locked at 40kHz for maximum efficiency. Datasheet on ultrasonic transducers used here.

K21 - Two Station Intercom Price Photo Docs
Simple two wire intercom. Each unit with its own speaker, microphone and amplifier (LM386.) Can be modified to a hard wired "bug". With 4 strand ribbon cable the power can be sent to the remote "bug" unit from the receiving unit.

K26 - Fibre Optic Audio Link Price Docs
Allows you to send sound through plastic 1mm fibre optic cable. Matched transmitter/receiver pair. Two circuit boards with a microphone at one end and a speaker at the other. 14 feet of fibre optic cable supplied. Will work over 200 meters.

K29 - Combination Lock Price Photo Docs
A basic but fully working combination lock. Separate touch pad with 9 pads. Lock is reset if an incorrect digit is pressed. Relay is capable of switching 12VDC/120VAC @ 10A. 12V operation. Robust and versatile.

K30 - PIR Movement Detector Price Photo Docs
Circuit designed around a recently developed movement IC. Circuit utilizes PIR detector and a light dependent resistor (LDR) to provide an optimized circuit that will detect motion up to 6 metres away. Operates on 9-12 VDC. Note that the PIR sensor & the PCB-mounted fresnel lens fit on the other side of the PCB; the solder side. This is to allow the unit to be mounted inside a container with the detecting lens poking out and the controls facing inside the box.

K33 - Tape Recorder Switch for Telephone Price Photo Docs
This kit uses a FET to switch on a tape recorder when the phone is picked up. It will work with low voltage tape recorders as low as 1.5V. It requires the REMOTE & MIC jacks of the tape recorder to be available. Plugs are provided.

K55 - Suction Cup Telephone Pickup Price Photo Docs
Uses a suction cup to attach to your telephone handset. Picks up the magnetic field produced in the earpiece by both sides of a telephone conversation. Feeds into an 8 ohm speaker after amplification. Volume control trimpot built in.

K76 - PIR module, cable connection, (assembled), KC7783 PricePhoto Docs
A fully assembled and tested miniature PIR module with only 3 connections: Power, Ground & Output. Rated for 5 - 10VDC input power. Has 2 1/2" cable attached as shown in the photo. Uses RE200B PIR sensor (datasheet page 1, page 2), KC778B movement detector IC (datasheet page 1, page 2) and PCB mounted Fresnel lens. Output is an active high pulse of approx. 0.5 seconds and remains active as long as there is motion. Range up to 3 metres. Sensitivity is fixed. Small size, 25 x 35mm (1" x 1.35").

K130 - IR Light Fence/Door Minder Price Photo Docs
Set up an invisible infra-red light beam to monitor doorways or any other area. When the beam is broken a relay (maims rated) is tripped which can be used to sound a bell or alarm. Ideal for customers entering a shop, cars coming up a driveway, etc. Separate transmitter and receiver boards. Transmitter can be powered from receiver board (extra plugs supplied). Uses modulated 38KHz carrier signal. 9-12VDC operation. IR LED and sensor datasheets.